U.S. patent application number 17/717442 was filed with the patent office on 2022-08-04 for methods and apparatuses for production of carbon, carbide electrodes, and carbon compositions.
The applicant listed for this patent is West Virginia University Research Corporation. Invention is credited to ALFRED H. STILLER, Christopher Yurchick.
Application Number | 20220248272 17/717442 |
Document ID | / |
Family ID | 1000006272400 |
Filed Date | 2022-08-04 |
United States Patent
Application |
20220248272 |
Kind Code |
A1 |
STILLER; ALFRED H. ; et
al. |
August 4, 2022 |
METHODS AND APPARATUSES FOR PRODUCTION OF CARBON, CARBIDE
ELECTRODES, AND CARBON COMPOSITIONS
Abstract
Method comprising providing at least one solid carbide chemical
compound and reducing a metal cation with use of the solid carbide
chemical compound. A method comprising producing elemental carbon
material from the oxidation of carbide in at least one carbide
chemical compound (e.g., calcium carbide) in at least one anode of
an electrochemical cell apparatus, such as a galvanic cell
apparatus. The cathode can be a variety of metals such as zinc or
tin. The reaction can be carried out at room temperature and normal
pressure. An external voltage also can be applied, and different
forms of carbon can be produced depending on the reactants used and
voltage applied. For carrying out the method, an apparatus
comprising at least one galvanic cell comprising: at least one
anode comprising at least one carbide chemical compound, and at
least one cathode. For carrying out the method and constructing the
apparatus, an electrode structure comprising at least one carbide
chemical compound, wherein the carbide chemical compound is a
salt-like carbide; and at least one electronically conductive
element different from the carbide. Carbon compositions of various
forms are also prepared by the methods and apparatus and with use
of the electrode structure. Large pieces of pure carbon can be
produced. Post-reaction processing of the carbon can be carried out
such as exfoliation.
Inventors: |
STILLER; ALFRED H.;
(Morgantown, WV) ; Yurchick; Christopher;
(Fairmont, WV) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
West Virginia University Research Corporation |
Morgantown |
WV |
US |
|
|
Family ID: |
1000006272400 |
Appl. No.: |
17/717442 |
Filed: |
April 11, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15886660 |
Feb 1, 2018 |
10904801 |
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17717442 |
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14886319 |
Oct 19, 2015 |
9909222 |
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15886660 |
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62066456 |
Oct 21, 2014 |
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62174760 |
Jun 12, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 48/16 20130101;
H04W 72/1278 20130101; H04W 28/26 20130101; H04W 72/0453 20130101;
H04W 16/14 20130101; H04W 72/1215 20130101; H04W 88/06 20130101;
H04W 88/10 20130101; H04W 74/002 20130101 |
International
Class: |
H04W 28/26 20060101
H04W028/26; H04W 72/04 20060101 H04W072/04; H04W 72/12 20060101
H04W072/12; H04W 74/00 20060101 H04W074/00 |
Claims
1. An electrode structure comprising at least one carbide chemical
compound, wherein optionally the carbide chemical compound is a
salt-like carbide; and at least one electronically conductive
structural element different from the carbide chemical compound and
contacting the at least one carbide chemical compound.
2. The electrode structure of claim 1, wherein the carbide chemical
compound is methanide, acetylide, or sesquicarbide.
3. The electrode structure of claim 1, wherein the carbide chemical
compound is calcium carbide, aluminum carbide, sodium carbide,
magnesium carbide, lithium carbide, or beryllium carbide.
4. The electrode structure of claim 1, wherein the carbide chemical
compound is calcium carbide or aluminum carbide.
5. The electrode structure of claim 1, wherein the carbide chemical
compound has sufficient electronic conductivity to function as an
anode.
6. The electrode structure of claim 1, wherein the carbide chemical
compound has an electronic conductivity of at least 10.sup.-8
S/cm.
7. The electrode structure of claim 1, wherein the carbide chemical
compound is in the form of individual pieces or particles.
8. The electrode structure of claim 1, wherein the carbide chemical
compound is in the form of individual pieces or particles having a
size of less than one cm.
9. The electrode structure of claim 1, wherein the carbide chemical
compound is in the form of individual pieces or particles having a
size of at least one micron.
10. The electrode structure of claim 1, wherein the carbide
chemical compound is divided into separate portions which are each
contacted with at least one electrically conductive structural
element.
11. The electrode structure of claim 1, wherein the carbide
chemical compound is at least about 95% pure.
12. The electrode structure of claim 1, wherein the electronically
conductive structural element is a binder for the carbide chemical
compound.
13. The electrode structure of claim 1, wherein the electronically
conductive structural element is a container and the carbide
chemical compound is held in the container.
14. The electrode structure of claim 1, wherein the electronically
conductive structural element is a container and the carbide
chemical compound is held in the container, and the container has
openings which allow fluid to enter the container and contact the
carbide chemical compound.
15. The electrode structure of claim 1, wherein the electronically
conductive structural element is a metallic container and the
carbide chemical compound is held in the metallic container.
16. The electrode structure of claim 1, wherein the electronically
conductive structural element comprises at least one conductive
rod.
17. The electrode structure of claim 1, wherein the electrode
structure is adapted to be removably attached to an apparatus.
18. The electrode structure of claim 1, wherein the electronically
conductive structural element of the electrode structure comprises
at least one current collector.
19. The electrode structure of claim 1, wherein the electrode
structure is adapted for use as an anode in an electrochemical cell
apparatus for production of an elemental carbon material.
20. The electrode structure of claim 1, wherein the electrode
structure is adapted for use as an anode in a galvanic cell
apparatus for production of elemental carbon material.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional
application Ser. Nos. 62/066,456 filed Oct. 21, 2014 and Ser. No.
62/174,760 filed Jun. 12, 2015, which are each hereby incorporated
by reference in their entireties.
BACKGROUND
[0002] Carbon is a commercially essential element which in
elemental form is a material both found in nature (e.g., coal) and
is also made from industrial processes. Methods of making carbon
are essential to traditional and advanced technology industries.
Elemental carbon can be found in various forms and allotropes
including, for example, amorphous carbon, crystalline carbon,
carbon black, graphite, and diamond. Other forms of carbon include,
for example, glassy carbon, diamond like carbon, carbene, and
carbyne. Nature also provides different forms of coal which is
largely carbon. Carbon powder and carbon fibers are other forms of
carbon essential to industry.
[0003] Nanoscale forms of carbon are also known including
fullerenes (including C.sub.6.cndot. and C.sub.7.cndot.
fullerenes), carbon nanotubes (both single walled and
multi-walled), graphene (single layered or multi-layered), and
aerogels. Diamond can be made synthetically by high pressure/high
temperature routes or by physical or chemical vapor deposition
routes. Vapor deposition can produce microcrystalline or
nanocrystalline diamond in thin film form. Nanoscale forms of
carbon represent a critical aspect of newer and better devices
ranging from the next generation of miniaturized transistors to
more efficient batteries. Large area forms of nanoscale forms of
carbon such as thin diamond films and graphene are also
critical.
[0004] In general, carbon production is associated with arduous
process conditions such as high temperature, high pressure, vacuum,
and/or high energy sources like plasma. Such conditions generate
expense and are energy-intensive. They also generally lack
versatility (e.g., inability for a single process to be altered to
produce different allotropes of carbon, or different size scales of
carbon).
[0005] For example, DE 1667532 Greiner (1971) describes what is
said to be low temperature diamond production from an
electrochemical system which can include use of carbide in the
electrolyte with use of temperatures of 600.degree. C. to
1000.degree. C. However, no data are provided.
[0006] Also, U.S. Pat. No. 4,738,759 (1988) describes an
electrolysis process wherein calcium carbide can be subjected to
electrolysis to form graphite sponge at the anode. Temperatures are
used such as 700.degree. C. to 1,000.degree. C.
[0007] A Chen M.S. thesis, August 2002, Univ. N. Texas, describes
electrochemical deposition of films of amorphous carbon and diamond
like carbon (DLC). Electrochemical deposition was carried out using
a low temperature (less than -40.degree. C.) solution of acetylene
in liquid ammonia.
[0008] Kulak, Electrochem. Comm., 5, 2003, 301-305 describes room
temperature electrodeposition of very thin, porous film containing
carbon (50-100 nm thick) from a solution of lithium acetylide.
However, the microscopic images of the film indicate a low quality
material (FIG. 2) and much of the film is not carbon
apparently.
[0009] US 2011/0290655 (Nishikiori; Toyota) describes a method for
electrochemically depositing carbon film on an anode substrate
using a molten salt electrolyte bath comprising a carbide ion and
applying a DC voltage to deposit the carbon film. The bath
temperature is 250.degree. C. to 800.degree. C. The carbon film is
said to be mainly amorphous carbon including graphite-like carbon
according to x-ray diffraction.
[0010] Despite such advances, a need exists for better,
commercially friendly, and environmentally friendly approaches to
elemental carbon material production. This includes elemental
carbon material that has high elemental purity and also a
commercially useful structure and morphology. One also wants to be
able to control the form and morphology of the elemental carbon
material. Inexpensive methods are also needed.
SUMMARY
[0011] Embodiments and aspects described and claimed herein
include, for example, methods of making, apparatuses for carrying
out methods of making, components used in the apparatuses for
method of making, methods of using, and compositions produced by
the methods of making. Devices and derivative compositions which
comprise compositions of elemental carbon materials are also
described and claimed herein.
[0012] For example, a first aspect is a method comprising providing
at least one solid carbide chemical compound and reducing a metal
cation with use of the solid carbide chemical compound.
[0013] In one embodiment, the carbide chemical compound has an
electronic conductivity of at least 10.sup.-8 S/cm. In one
embodiment, the carbide chemical compound is a salt-like carbide.
In another embodiment, the carbide chemical compound is calcium
carbide or aluminum carbide.
[0014] In another embodiment, elemental carbon material is formed.
In another embodiment, elemental carbon material is formed which is
more than 50% sp2 carbon. In another embodiment, elemental carbon
material is formed which is more than 50% sp3 carbon. In another
embodiment, elemental carbon material is formed which is more than
90% carbon.
[0015] In another embodiment, the reducing is carried out at a
temperature of about 15.degree. C. to about 50.degree. C. In
another embodiment, the reducing is carried out at a pressure of
about 720 torr to about 800 torr. In another embodiment, the
reducing is carried out at a temperature of about 15.degree. C. to
about 50.degree. C. and at a pressure of about 720 torr to about
800 torr.
[0016] In another embodiment, the cation is a zinc, tin, iron,
copper, or silver cation. In another embodiment, the cation is a
zinc or tin cation.
[0017] In another embodiment, the reducing is carried out in an
electrochemical cell with a cathode compartment comprising the
metal cation and an anode compartment comprising the solid carbide
chemical compound.
[0018] In another embodiment, the reducing is carried out in a
galvanic cell with a cathode compartment comprising the metal
cation and an anode compartment comprising the solid carbide
chemical compound. In another embodiment, the reducing is carried
out in a galvanic cell with a cathode compartment comprising the
metal cation and an anode compartment comprising the solid carbide
chemical compound, and the galvanic cell further comprises at least
one external voltage source.
[0019] In another embodiment, the reducing is carried out in a
galvanic cell with a cathode compartment comprising the metal
cation and an anode compartment comprising the solid carbide
chemical compound, and the galvanic cell does not comprise at least
one external voltage source.
[0020] In another embodiment, the reducing is carried out without
contact between the metal cation and the solid carbide chemical
compound. In another embodiment, the reducing is carried out with
contact between the metal cation and the solid carbide chemical
compound. In another embodiment, the reducing is carried out with
contact between the metal cation and the solid carbide chemical
compound, and the metal cation is dissolved in at least one organic
solvent.
[0021] In addition, a second aspect provides for a method
comprising: producing elemental carbon material from the oxidation
of carbide in at least one carbide chemical compound in at least
one anode of an electrochemical cell apparatus. More particularly,
a method is providing comprising: producing elemental carbon
material from the oxidation of carbide in at least one carbide
chemical compound in at least one anode of a galvanic cell
apparatus
[0022] In one embodiment, the electrochemical cell apparatus is a
galvanic cell apparatus or an electrolytic cell apparatus. In
another embodiment, the electrochemical cell apparatus is a
galvanic cell apparatus.
[0023] In another embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. In
another embodiment, the carbide chemical compound is a salt-like
carbide. In another embodiment, the carbide chemical compound is a
methanide, an acetylide, or a sesquicarbide. In another embodiment,
the carbide chemical compound is calcium carbide, aluminum carbide,
sodium carbide, magnesium carbide, lithium carbide, beryllium
carbide, iron carbide, copper carbide, and chromium carbide. In
another embodiment, the carbide chemical compound is calcium
carbide or aluminum carbide. In another embodiment, the carbide
chemical compound has sufficient electronic conductivity to
function as an anode. In another embodiment, the carbide chemical
compound has an electronic conductivity of at least 10.sup.-8
S/cm.
[0024] In another embodiment, the electrochemical cell apparatus
further comprises at least one cathode. In another embodiment, the
electrochemical cell apparatus further comprises at least one
cathode which is a metal cathode. In another embodiment, the
electrochemical cell apparatus further comprises at least one metal
cathode, wherein the cathode is a zinc, tin, iron, copper, or
silver cathode. In another embodiment, the electrochemical cell
apparatus further comprises at least one metal cathode, wherein the
cathode is a zinc or tin cathode.
[0025] In another embodiment, the electrochemical cell apparatus
anode is contacted with at least one first solution comprising at
least one solvent and at least one salt and a galvanic cell
apparatus cathode is also contacted with at least one solution
comprising at least one solvent and at least one salt.
[0026] In another embodiment, the electrochemical cell apparatus
further comprises at least one salt bridge. In another embodiment,
the electrochemical cell apparatus further comprises at least one
ion exchange membrane.
[0027] In another embodiment, the reaction temperature for
producing the elemental carbon material is about 10.degree. C. to
about 90.degree. C. In another embodiment, the reaction temperature
for producing the elemental carbon material is about 15.degree. C.
to about 50.degree. C. In another embodiment, the reaction
temperature for producing the elemental carbon material is about
room temperature. In another embodiment, the reaction pressure for
producing the elemental carbon material is about 0.1 torr to about
5 atmospheres. In another embodiment, the reaction pressure for
producing the elemental carbon material is about 720 torr to about
800 torr. In another embodiment, the elemental carbon material is
produced at about normal pressure.
[0028] In another embodiment, the production of elemental carbon
material is carried out without use of an external voltage source.
In another embodiment, the electrochemical cell apparatus comprises
an external voltage source to regulate the oxidation reaction. In
another embodiment, the production of carbon is carried out with
use of an external voltage source to regulate the oxidation
reaction. In another embodiment, the production of carbon is
carried out with use of an external voltage source to regulate the
oxidation reaction, and an external voltage is used at a particular
voltage to enhance production of one elemental carbon material
product over other different elemental carbon products.
[0029] In another embodiment, the elemental carbon material is more
than 50% sp2 carbon. In another embodiment, the elemental carbon
material is more than 50% sp3 carbon. In another embodiment, the
elemental carbon material is more than 90% carbon.
[0030] In another embodiment, the elemental carbon material
comprises two-dimensional plate-like structures. In another
embodiment, the elemental carbon material comprises two-dimensional
plate-like structures stacked on top of one another. In another
embodiment, the elemental carbon material comprises at least some
three-dimensional structures. In another embodiment, the elemental
carbon material comprises at least some pieces which have a lateral
dimension of at least one mm.
[0031] In another embodiment, the elemental carbon material is
subjected to at least one purification step. In another embodiment,
the elemental carbon material is treated with acid and water. In
another embodiment, the elemental carbon material is subjected to
at least one step which produces particles of the elemental carbon
material. In another embodiment, the elemental carbon material is
subjected to at least one exfoliation step to produce graphene.
[0032] In another embodiment, the electrochemical cell apparatus is
a galvanic cell apparatus which produces electrical power to power
at least one load which is another electrochemical cell.
[0033] In another embodiment, the electrochemical cell apparatus is
a galvanic cell apparatus, the carbide chemical compound is calcium
carbide or aluminum carbide, wherein the galvanic cell apparatus
anode is contacted with a solution comprising at least one organic
solvent and at least one dissolved salt, and the galvanic cell
apparatus cathode is also contacted with a solution comprising at
least one organic solvent and at least one dissolved salt, and
wherein the elemental carbon material is produced at about
15.degree. C. to about 50.degree. C. and about 720 torr to about
800 torr.
[0034] Another aspect provides for an apparatus comprising at least
one electrochemical cell apparatus comprising: at least one anode
comprising at least one carbide chemical compound, and at least one
cathode. More particularly, an apparatus is provided comprising at
least one galvanic cell apparatus comprising: at least one anode
comprising at least one carbide chemical compound, and at least one
cathode. In one embodiment, the electrochemical cell apparatus is a
galvanic cell apparatus or an electrolytic cell apparatus. In
another embodiment, the electrochemical cell apparatus is a
galvanic cell apparatus.
[0035] In another embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. In
another embodiment, the carbide chemical compound is a salt-like
carbide. In another embodiment, the carbide chemical compound is
calcium carbide or aluminum carbide. In another embodiment, the
carbide chemical compound has sufficient electronic conductivity to
function as an anode. In another embodiment, the carbide chemical
compound has an electronic conductivity of at least 10.sup.-8 S/cm.
In another embodiment, the carbide chemical compound is in the form
of individual pieces or particles. In another embodiment, the
carbide chemical compound is in the form of individual pieces or
particles having a size of less than one cm. In another embodiment,
the carbide chemical compound contacts at least one electrically
conductive material. In another embodiment, the carbide chemical
compound is held in an electrically conductive container.
[0036] In another embodiment, the electrochemical cell apparatus
anode is contacted with a solution comprising at least one organic
solvent and at least one dissolved salt. In another embodiment, the
electrochemical cell apparatus cathode is contacted with a solution
comprising at least one organic solvent and at least one dissolved
salt. In another embodiment, the electrochemical cell apparatus
cathode is a metal cathode. In another embodiment, the
electrochemical cell apparatus comprises at least one salt bridge
or at least one ion exchange membrane. In another embodiment, the
electrochemical cell apparatus comprises an external voltage source
to regulate an oxidation reaction of carbide in the carbide
chemical compound. In another embodiment, the apparatus further
comprises at least one solution comprising at least one solvent and
at least one dissolved salt, and the solution is free of dissolved
carbide chemical compound.
[0037] In another embodiment, an electrochemical cell apparatus is
provided for carrying out the methods described herein. In
particular, a galvanic cell apparatus is provided for carrying out
the methods described herein.
[0038] In another embodiment, the anode is an anode electrode
structure comprising at least one carbide chemical compound,
wherein optionally the carbide chemical compound is a salt-like
carbide; and at least one electronically conductive structural
element different from the carbide chemical compound and contacting
the at least one carbide chemical compound.
[0039] Still further, another aspect provides for an electrode
structure comprising at least one carbide chemical compound,
wherein optionally the carbide chemical compound is a salt-like
carbide; and at least one electronically conductive structural
element different from the carbide chemical compound and contacting
the at least one carbide chemical compound. The electrode structure
can be a solid electrode structure; also, the electrode structure
can be adapted to function as an anode.
[0040] In one embodiment, the carbide chemical compound is
methanide, acetylide, or sesquicarbide. In another embodiment, the
carbide chemical compound is calcium carbide, aluminum carbide,
sodium carbide, magnesium carbide, lithium carbide, or beryllium
carbide. In another embodiment, the carbide chemical compound is
calcium carbide or aluminum carbide. In another embodiment, the
carbide chemical compound has sufficient electronic conductivity to
function as an anode. In another embodiment, the carbide chemical
compound has an electronic conductivity of at least 10.sup.-8 S/cm.
In another embodiment, the carbide chemical compound is in the form
of individual pieces or particles. In another embodiment, the
carbide chemical compound is in the form of individual pieces or
particles having a size of less than one cm. In another embodiment,
the carbide chemical compound is in the form of individual pieces
or particles having a size of at least one micron. In another
embodiment, the carbide chemical compound is divided into separate
portions which are each contacted with at least one electrically
conductive structural element. In another embodiment, the carbide
chemical compound is at least about 95% pure.
[0041] In another embodiment, the electronically conductive
structural element is a binder for the carbide chemical compound.
In another embodiment, the electronically conductive structural
element is a container and the carbide chemical compound is held in
the container. In another embodiment, the electronically conductive
structural element is a container and the carbide chemical compound
is held in the container, and the container has openings which
allow fluid to enter the container and contact the carbide chemical
compound. In another embodiment, the electronically conductive
structural element is a metallic container and the carbide chemical
compound is held in the metallic container. In another embodiment,
the electronically conductive structural element comprises at least
one conductive rod. In another embodiment, the electrode structure
is adapted to be removably attached to an apparatus. In another
embodiment, the electronically conductive structural element of the
electrode structure comprises at least one current collector. In
another embodiment, the electrode structure is adapted for use as
an anode in an electrochemical cell apparatus for production of an
elemental carbon material. In another embodiment, the electrode
structure is adapted for use as an anode in a galvanic cell
apparatus for production of elemental carbon material.
[0042] Another aspect provides for a method comprising operating at
least one anode in an electrochemical cell, wherein the anode
comprises at least carbide chemical compound.
[0043] In one embodiment, the anode consists essentially of at
least one carbide chemical compound. In another embodiment, the
anode consists of at least one carbide chemical compound. In
another embodiment, the anode is part of an anode structure which
further comprises at least one electronically conductive structural
element different from the carbide chemical compound and contacting
the at least one carbide chemical compound. In another embodiment,
the anode is part of an anode structure which further comprises at
least one metallic structural element different from the carbide
chemical compound and contacting the at least one carbide chemical
compound. In another embodiment, the carbide chemical compound has
sufficient electronic conductivity to function as an anode. In
another embodiment, the carbide chemical compound has an electronic
conductivity of at least 10.sup.-8 S/cm. In another embodiment, the
carbide chemical compound is a salt-like carbide. In another
embodiment, the carbide chemical compound is calcium carbide or
aluminum carbide. In another embodiment, the electrochemical cell
is a galvanic cell.
[0044] Another aspect is for a method comprising: producing
elemental carbon material from the oxidation of carbide in at least
one carbide chemical compound which is in contact with a solution
comprising at least one organic solvent and at least one dissolved
salt comprising at least one metal cation which is reduced.
[0045] In one embodiment, the reaction temperature for producing
the elemental carbon material is about 10.degree. C. to about
90.degree. C. In another embodiment, the reaction temperature for
producing the elemental carbon material is about 15.degree. C. to
about 50.degree. C. In another embodiment, the reaction temperature
for producing the elemental carbon material is about room
temperature. In another embodiment, the reaction pressure for
producing the elemental carbon material is about 0.1 torr to about
5 atmospheres. In another embodiment, the reaction pressure for
producing the elemental carbon material is about 720 torr to about
800 torr.
[0046] In another embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. In
another embodiment, the carbide chemical compound is a salt-like
carbide. In another embodiment, the carbide chemical compound is a
methanide, an acetylide, or a sesquicarbide. In another embodiment,
the carbide chemical compound is calcium carbide or aluminum
carbide.
[0047] Another aspect provides for an elemental carbon material
composition (i) prepared by the methods described and/or claimed
herein; and/or (ii) characterized as described and/or claimed
herein. The elemental carbon material can be in an unpurified form,
a partially purified form, a purified form, a processed form, a
doped form, and/or a reacted form.
[0048] In one embodiment, the elemental carbon material is more
than 50% sp2 carbon. In another embodiment, the elemental carbon
material is more than 50% sp3 carbon. In another embodiment, the
elemental carbon material is more than 90% carbon.
[0049] In another embodiment, the elemental carbon material
comprises two-dimensional plate-like structures. In another
embodiment, the elemental carbon material comprises two-dimensional
plate-like structures stacked on top of one another. In another
embodiment, the elemental carbon material comprises graphene
structures. In another embodiment, the elemental carbon material
comprises graphite structures. In another embodiment, wherein the
elemental carbon material comprises three-dimensional structures.
In another embodiment, the elemental carbon material comprises
diamond. In another embodiment, the elemental carbon material
comprises diamond structures and/or diamond-like structures. In
another embodiment, the elemental carbon material comprises at
least one piece which has a lateral dimension of at least one mm,
at least one cm. In another embodiment, the elemental carbon
material comprises at least one piece which has a volume of at
least one cubic mm, or at least one cubic cm.
[0050] Also provided herein are one or more composition comprising
the elemental carbon material compositions described herein. For
example, the elemental carbon material can be mixed with one or
more different ingredients.
[0051] Also provided herein are one or more devices, apparatuses,
or systems comprising the compositions described herein such as,
for example, a battery device, an electronic device, or a
filtration device. Other embodiments include making and using such
devices, apparatuses, and systems.
[0052] At least some advantages for at least some embodiments
described and/or claimed herein include, for example, (i) an
ambient temperature and/or a normal pressure reaction process to
form high purity elemental carbon materials of very high carbon
content; (ii) cost-effectiveness; (iii) environmental friendliness;
and/or (iv) ability to control the nature of the elemental carbon
material product in versatile ways.
[0053] More particularly, one of the most important advantages for
at least some of the embodiments is the ability to produce an array
of different elemental carbon material reaction products in
different forms. Therefore, the technology can yield numerous
processes with many value added end products. Also, because of the
physical states when the reaction occurs (the liquid state and
solid state), one can enable the production of the various
allotropes of elemental carbon material at a higher quality level
than any of the competing elemental carbon production
technologies.
[0054] Another major advantage for at least some embodiments is
scalability. For example, the electrochemical and galvanic reaction
mechanism for oxidizing carbides to various allotropes and forms of
elemental carbon materials is very scalable, meaning that the
technology can be increased in size without any major re-designs.
Typically, the main obstacles with increasing the scale of a
process are physical limitations of the equipment at extreme
conditions and gradients (e.g., temperature, concentration, etc.)
within larger equipment as the scale increases. However, in most
embodiments presently described and claimed, there are no extreme
conditions in these processes. For example, preferably, the process
is operated at or near room temperature and atmospheric pressure so
there is little concern about the limitations of the equipment at
extreme conditions as size is increased. Still other advantages are
described and evident in this application.
BRIEF DESCRIPTION OF THE FIGURES
[0055] The figures provide more description for representative
embodiments including many working examples.
[0056] FIG. 1 is a chart that provides the enthalpies of formation
for various allotropes of carbon.
[0057] FIG. 2 is a schematic diagram of a representative
electrochemical (here, galvanic) system according to an embodiment
of the invention.
[0058] FIG. 3 is a diagram of a representative electrochemical
(here, galvanic) system according to an embodiment of the invention
showing a direct current (DC) source and a variable resistor (i.e.,
example of external voltage source).
[0059] FIG. 4 shows a schematic drawing of the apparatus wherein an
ion exchange membrane is below the two cells.
[0060] FIG. 5 shows a schematic drawing of the apparatus in which
an ion exchange membrane is used and also a reference electrode
(Ag/AgCl) is used.
[0061] FIG. 6 shows SEM data for elemental carbon material prepared
by a comparative thermal method (U.S. application Ser. No.
14/213,533 and PCT Application PCT/US2014/028755; scale bar 200
microns). One relatively larger piece is evident.
[0062] FIG. 7 shows additional SEM data for elemental carbon
material prepared by a comparative thermal method ((U.S.
application Ser. No. 14/213,533 and PCT Application
PCT/US2014/028755; scale bar 200 microns).
[0063] FIG. 8 is a Scanning Electron Microscope (SEM) image showing
elemental carbon material reaction product on a bulk material scale
(Example 1; zinc). The scale bar is 50 microns.
[0064] FIG. 9 is an SEM image showing the plate-like structures
found in the elemental carbon material reaction product (Example 1;
zinc). The scale bar is five microns.
[0065] FIG. 10 is an SEM image showing the plate-like structures
found in the elemental carbon material reaction product (Example 1;
zinc). The scale bar is two microns.
[0066] FIG. 11 is an SEM image showing the plate-like structures
found in the elemental carbon material reaction product (Example 1;
zinc). The scale bar is five microns.
[0067] FIG. 12 is an SEM image showing carbon reaction product on a
bulk material scale (Example 2; tin). The scale bar is 100
microns.
[0068] FIG. 13 is an SEM image showing the elemental carbon
material reaction product (Example 2; tin). The scale bar is 20
microns.
[0069] FIG. 14 is an SEM image showing the three-dimensional
crystals of elemental carbon material (Example 2; tin). The scale
bar is ten microns.
[0070] FIG. 15 is an SEM image showing a three-dimensional
elemental carbon material particle (Example 2; tin). The scale bar
is 10 microns.
[0071] FIG. 16 is an SEM image showing the top region of the
three-dimensional elemental carbon material particle (Example 2;
tin). The scale bar is 3 microns.
[0072] FIG. 17 is photograph depiction of a representative,
relatively smaller bench-scale sized electrochemical system
(Examples 1 and 2).
[0073] FIG. 18 shows a photograph of a modified laboratory-scale
apparatus similar to the apparatus of FIG. 17 but adapted with an
ion exchange membrane.
[0074] FIG. 19 is a diagram of a representative, relatively larger
bench-scale sized electrochemical system compared to that of FIGS.
17 and 18 (Examples 3 and 4).
[0075] FIG. 20 is a photograph depiction of a representative larger
bench-scale sized electrochemical system showing the two cells
(Examples 3 and 4).
[0076] FIG. 21 is a photograph depiction of a representative
carbide cell according to an embodiment of the invention (Examples
3 and 4).
[0077] FIG. 22 is a photograph depiction of a representative zinc
cell according to an embodiment of the invention (Examples 3 and
4).
[0078] FIG. 23 is a photograph depiction of a representative salt
bridge connecting the carbide and zinc cells according to an
embodiment of the invention (Examples 3 and 4).
[0079] FIG. 24 shows SEM data for the elemental carbon material
prepared in Example 3 (scale bar 10 microns).
[0080] FIG. 25 shows SEM data for the elemental carbon material
prepared in Example 3 (scale bar 20 microns).
[0081] FIG. 26 shows SEM data for the elemental carbon material
prepared in Example 3 (scale bar 50 microns).
[0082] FIG. 27 shows Raman spectral data (eight traces) for the
elemental carbon material prepared in Example 3.
[0083] FIG. 28 shows SEM data for the elemental carbon material
prepared in Example 4 (scale bar 20 microns).
[0084] FIG. 29 shows additional SEM data for the elemental carbon
material prepared in Example 4 (scale bar 20 microns).
[0085] FIG. 30 shows EDAX data for the elemental carbon material
prepared in Example 4.
[0086] FIG. 31 shows Raman spectral data for the elemental carbon
material prepared in Example 4.
[0087] FIG. 32 is an SEM image showing more of the elemental carbon
material of Example 4 (scale bar, 50 microns).
[0088] FIG. 33 shows a comparison for a large piece of elemental
carbon material from Example 5 (33 left) with a commercial graphene
product having relatively smaller pieces (33 right), each with a
200 micron scale bar.
[0089] FIG. 34 is an SEM image showing a top view of a large piece
of carbon product (Example 5, Sample C) (scale bar, 200
microns).
[0090] FIG. 35 is an SEM image showing Sample C with a perspective
view (Example 5, scale bar, 200 microns).
[0091] FIG. 36 is a Raman spectrum (four traces) for Sample C
(Example 5).
[0092] FIG. 37 is an SEM image showing Sample C (Example 5) and
material morphology within crevices (scale bar, 40 microns).
[0093] FIG. 38 shows an optical micrograph for top view of Sample C
(Example 5, scale bar, 390 microns).
[0094] FIG. 39 shows an optical micrograph for perspective view of
edge of Sample C (Example 5, scale bar, 240 microns).
[0095] FIG. 40 is an SEM image showing Sample C (Example 5, scale
bar, 30 microns).
[0096] FIG. 41 is an SEM image showing Sample C, for an enlarged
view of FIG. 40 (scale bar, 5 microns).
[0097] FIG. 42 shows a comparison for elemental carbon material
prepared by a comparative thermal method (42 left; U.S. application
Ser. No. 14/213,533 and PCT Application PCT/US2014/028755) with a
large piece of elemental carbon material prepared in Example 5 (42
right), each with scale bar of 200 microns.
[0098] FIG. 43 shows a comparison for elemental carbon material
prepared by a comparative thermal method (43 left; U.S. application
Ser. No. 14/213,533 and PCT Application PCT/US2014/028755) with a
large piece of elemental carbon material prepared in Example 5 (43
right), each with scale bar of 30 microns.
[0099] FIG. 44 shows a comparison for elemental carbon material
prepared by a comparative thermal method (44 left; U.S. application
Ser. No. 14/213,533 and PCT Application PCT/US2014/028755) with a
large piece of elemental carbon material prepared in Example 5 (44
right), each with scale bar of 5 microns.
[0100] FIG. 45 shows a comparison for Raman spectra for elemental
carbon material prepared by a comparative thermal method (45 left,
U.S. application Ser. No. 14/213,533 and PCT Application
PCT/US2014/02875545A) with Raman spectra for a large piece of
elemental carbon material prepared in Example 5 (45 right).
[0101] FIG. 46 is a first SEM image showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(scale bar 10 microns).
[0102] FIG. 47 is an SEM image showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(scale bar 5 microns).
[0103] FIG. 48 is an SEM image showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(scale bar 50 microns).
[0104] FIG. 49 shows two SEM images showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(49 left, scale bar 50 microns; 49 right, scale bar 10
microns).
[0105] FIG. 50 shows two SEM images showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(50 left, scale bar 10 microns; 50 right, scale bar 10
microns).
[0106] FIG. 51 is an SEM image showing the elemental carbon
material product in Example 6 with use of a potentiostat, Sample D
(scale bar 10 microns).
[0107] FIG. 52 shows SEM data for the elemental carbon material
prepared in Example 6 (scale bar 100 microns).
[0108] FIG. 53 shows SEM data for the elemental carbon material
prepared in Example 6 (scale bar 30 microns).
[0109] FIG. 54 shows SEM data for the elemental carbon material
prepared in Example 6 (scale bar 10 microns).
[0110] FIG. 55 shows SEM data for the elemental carbon material
prepared in Example 6 (scale bar 100 microns).
[0111] FIG. 56 shows SEM data for the elemental carbon material
prepared in Example 6 (scale bar 20 microns).
[0112] FIG. 57 shows Raman spectral data (seven traces) for the
elemental carbon material prepared in Example 6.
[0113] FIG. 58 shows SEM data for the elemental carbon material
prepared in Example 8 (scale bar, 50 microns).
[0114] FIG. 59 shows SEM data for the elemental carbon material
prepared in Example 8 (scale bar, 10 microns).
[0115] FIG. 60 shows Raman spectral data for elemental carbon
material prepared in Example 8.
[0116] FIG. 61 shows SEM data for the elemental carbon material
prepared in Example 9 (scale bar, 5 microns).
[0117] FIG. 62 shows SEM data for the elemental carbon material
prepared in Example 9 (scale bar, 10 microns).
[0118] FIG. 63 shows Raman spectral data for elemental carbon
material prepared in Example 9.
[0119] FIG. 64 shows SEM data for the elemental carbon material
prepared in Example 10 (scale bar, 200 microns).
[0120] FIG. 65 shows SEM data for the elemental carbon material
prepared in Example 10 (scale bar, 30 microns).
[0121] FIG. 66 shows SEM data for the elemental carbon material
prepared in Example 10 (scale bar, 10 microns).
[0122] FIG. 67 shows Raman spectra for Example 10.
[0123] FIG. 68 shows SEM data for the elemental carbon material
prepared in Example 11 (scale bar, 10 microns).
[0124] FIG. 69 shows SEM data for the elemental carbon material
prepared in Example 11 (scale bar, 40 microns).
[0125] FIG. 70 shows SEM data for the elemental carbon material
prepared in Example 11 (scale bar, 30 microns).
[0126] FIG. 71 shows Raman spectral data for elemental carbon
material prepared in Example 11.
DETAILED DESCRIPTION
I. Introduction
[0127] The various aspects and claims summarized above and claimed
below are described in more detail hereinafter including with use
of working examples.
[0128] References cited herein are incorporated by reference.
[0129] Priority U.S. provisional application Ser. Nos. 62/066,456
filed Oct. 21, 2014 and Ser. No. 62/174,760 filed Jun. 12, 2015 are
each hereby incorporated by reference in their entireties including
their summaries, detailed descriptions, working examples, and
figures.
[0130] U.S. application Ser. No. 14/213,533, filed Mar. 14, 2014
and published as 2014/0271441, describes a method of making carbon
from carbide and molten, metal salts in a thermal process but at
relatively low temperature compared to prior art processes. PCT
Application PCT/US2014/028755, filed Mar. 14, 2014 and published as
WO 2014/144374, also describes a method of making carbon from
carbide and molten, metal salts in a thermal process but at a
relatively low temperature. Also described are processing steps to
purify and treat the elemental carbon material. FIGS. 6 and 7 show
examples of elemental carbon materials prepared by these
methods.
[0131] In addition, the claim transitions "comprising," "consisting
essentially of," and "consisting of" can be used to describe and/or
claim the various embodiments described herein. Basic and novel
features of the invention are described herein.
[0132] In a nutshell, embodiments for the present inventions
provide for, among other things, methods of reacting carbides to
produce elemental carbon material and carbon allotropes.
[0133] In some embodiments of the present inventions, a voltage is
varied, changed, or altered in a cell in which one of the cells
contains a carbide electrode to change the nature of the elemental
carbon materials formed by the oxidation of carbide anions. Voltage
may be varied, changed, or altered in a cell in which one of the
cells is a carbide to change the nature of the carbon materials
formed by the oxidation of acetylide anions, methanide anions,
and/or sesquicarbide anions. In some embodiments, the carbon
allotropes produced by the process are controlled by controlling
the voltage between the cells in which one of the cells is a
carbide.
[0134] For more background to the presently claimed inventions,
FIG. 1 is a chart that provides the enthalpies of formation for
forms and allotropes of carbon prepared from a carbide reactant.
FIG. 1 provides the associated heats of formation
DH.sub.(formation) in descending order with the lower the
DH.sub.(formation) value the more stable the state of carbon, with
graphite being in the most stable state. The sources for FIG. 1 are
an NIST webbook, the textbook Elements of Physical Chemistry (Peter
Atkins), and Cherkasov, Nikolay B. et al., Carbon, vol. 36, p.
324-329.
II. Methods of Production
[0135] A first aspect for a method of making is a method comprising
providing at least one solid carbide chemical compound and reducing
a metal cation with use of the solid carbide chemical compound. The
reducing can result from a spontaneous, galvanic reaction,
optionally with application of an external voltage. Alternatively,
the reducing can be carried out with a non-spontaneous reaction
with application of an external voltage.
[0136] A second aspect for a method of making provides for a method
comprising: producing elemental carbon material from the oxidation
of carbide in at least one carbide chemical compound in at least
one anode of an electrochemical cell apparatus. Apparatuses which
can used to carry out this method are described further in, for
example, Part III of this application (see also, for example,
Schematics in FIGS. 2-5 and 19). Also, carbide electrode structures
which can be used to carry out this method are described further
in, for example, Part IV of this application (including methods of
using carbide electrodes).
[0137] Still further, a third aspect for a method of making is for
a method comprising: producing elemental carbon material from the
oxidation of carbide in at least one carbide chemical compound
which is in contact with a solution comprising at least one organic
solvent and at least one dissolved salt comprising at least one
metal cation which is reduced.
[0138] Finally, elemental carbon material reaction products which
can be formed from these methods are described further in Part V of
this application.
[0139] The method of making can be based on a electrochemical cell
apparatus which can be galvanic (spontaneous reaction) or
electrolytic (non-spontaneous reaction). Preferably, the method
makes use of a galvanic reaction using a galvanic cell apparatus.
Preferably, the reaction is a spontaneous redox reaction. A
galvanic reaction is generally known in the art as a spontaneous
redox reaction wherein one moiety is oxidized and another moiety is
reduced. The moieties are connected electrically to allow current
to flow and the redox reaction to occur. A multimeter can be used
to measure voltage and current flow for such a reaction. No
external electrical potential is needed to induce the spontaneous
reaction in a galvanic reaction. However, an external electrical
potential can be used to control or modify the galvanic reaction,
while the reaction is still called a "galvanic reaction" or a
"spontaneous reaction." The discharge of the current flow can be
regulated. The galvanic reaction can be a source of power, voltage,
and current, and these reactions can be used to power other systems
and loads as known in the art.
[0140] The elements of a method using a galvanic reaction are known
and described more hereinbelow. They include, for example, at least
one anode, at least one cathode, and connections between the anode
and cathode to allow current flow and form a circuit. The
connections can provide electronic or ionic current flow. For
example, wiring can be used and devices can be used to measure the
potential and current flow. Ionic flow can be enabled with use of
salt bridges or ion exchange membranes. The salt bridge or ion
exchange membrane can have a geometry and length which help to
determine the rate of the redox reaction. The transport of the
appropriately charged moiety, an anion, can be mediated through the
salt bridge or the ion exchange membrane to complete the circuit.
For instance, in one embodiment, a cation such as a zinc cation
dissolved in the solution in the metal cell cannot migrate or
transfer through the ion exchange membrane. However the anion
(e.g., Cl--) is able to diffuse through the membrane and into the
carbide cell. In one embodiment, the salt bridge is replaced with,
or used with, or comprises an ion exchange membrane. In any event,
the salt bridge or ion exchange membrane can be adapted to avoid
being a rate limiting step ("bottle neck") for the process and pass
as much charge as possible.
[0141] The elements of a method using an electrolytic reaction are
also known.
[0142] In one embodiment, the electrochemical cell (e.g., galvanic
cell) apparatus further comprises at least one cathode which can be
a metal cathode. Mixtures of metals can be used.
[0143] The cathode can be used in conjuction with a solution
comprising a dissolved salt including a metal cation and an anion.
In principle, any ion/metal combination where the ion can be
reduced to the metal can be used for a cathode employing this
method. More specifically, in principle, any elemental metal
immersed in a solution containing ions of that metal, where the
ions can be reduced to the elemental state in order to facilitate
the oxidation of the carbide ions to elemental carbon, can be used.
Examples include zinc metal in a solution of zinc ions, tin metal
in a solution of stannous ions, silver metal in a solution of
silver ions, and iron in a solution of ferrous ions. In selecting
the cathode, practical considersations can be taken into account.
For example, issues like corrosion of the metal cathode can be
considered. Other factors to consider include, for example, the
characteristics of the solvent and the overall solution and how
they would interact with the different components of the reaction
system. Solubility of the various metallic salts in the different
solvents or solvent combinations would also be an issue.
[0144] In one embodiment, the electrochemical cell (e.g., galvanic
cell) apparatus further comprises at least one metal cathode,
wherein the cathode is a zinc, tin, iron (include steel), copper,
or silver metal cathode. In another embodiment, the electrochemical
cell (e.g., galvanic cell) apparatus further comprises at least one
metal cathode, wherein the cathode is a zinc or tin metal
cathode.
[0145] In one embodiment, the galvanic cell apparatus anode is
contacted with at least one first solution comprising at least one
first solvent and at least one first salt and a galvanic cell
apparatus cathode is also contacted with at least one second
solution comprising at least one second solvent and at least one
second salt. The solvent and salt combination for both the anode
and cathode sides of the cell should provide sufficient ionic
conductivity for the process to be enabled. The viscosity of the
solvent can be also considered in solvent selection for first and
second solvent. For first and second solvent, the solvent can be,
for example, a polar organic solvent such as an alcohol such as
methanol or ethanol, or an ether such as tetrahydrofuran, or an
aprotic solvent such as DMSO or NMP. Examples of solvents include
N-methyl pyrrolidone, dimethyl formamide, acetone, tetrahydrofuran,
pyridine, acetonitrile, methanol, ethanol, tetramethylurea, and/or
dichlorobenzene. Mixtures of solvents can be used. In general,
water is avoided in the solvent, and solvents can be dried. In some
cases, slow reaction between the solvent and the carbide chemical
compound may occur. For example, methanol can reaction with calcium
carbide to form calcium methoxide. Typically, the reaction
apparatus should be relatively inert to the solvent so that side
reactions are minimized or avoided.
[0146] The salts for the cathode and anode sides of the cell can be
selected to provide the cation or the anion which enable the
reaction to work well. For example, the cathode metal being reduced
can be used in conjunction with a salt which has the oxidized metal
as cation. The anion of the salt can be a halide such as fluoride,
chloride, bromide, or iodide. However, the fluoride can cause a
high heat of reaction which can generate problems so fluoride salts
can be avoided. Chloride salts generally are preferred. Examples of
salts include zinc chloride, calcium chloride, stannous chloride,
ferrous chloride, cupric chloride, silver chloride, aluminum
chloride, lithium chloride, calcium fluoride, stannous fluoride,
aluminum fluoride, and lithium fluoride.
[0147] An important factor also is that the cation of the carbide
must form a soluble salt with the anion of the cathode cell. This
may not be possible in some cases such as some sulfate salts
including calcium sulfate.
[0148] In one embodiment, the galvanic cell apparatus further
comprises at least one salt bridge and/or at least one ion exchange
membrane. Ion exchange membranes are known in the art and typically
are made of a polymeric material attached to charged ion groups.
Anion exchange membranes contain fixed cationic groups with mobile
anions; they allow the passage of anions and block cations. Cation
exchange membranes contain fixed anionic groups with mobile
cations; they allow the passage of cations and block anions. See,
for example, Y. Tanaka, Ion Exchange Membranes: Fundamentals and
Applications, 2.sup.nd Ed., 2015. Herein, the use of ion exchange
membranes can help prevent formation of unwanted side products and
migration of undesired materials from one cell to the other
cell.
[0149] In one embodiment, steps are taken so that the reaction is
carried out under anhydrous conditions. Moisture can be excluded to
the extent needed. Also, inert gases can be used such as argon or
nitrogen.
[0150] The reaction time can be adapted to the need. Reaction time
can be, for example, one minute to 30 days, or one day to 20
days.
[0151] In one embodiment, the production of carbon is carried out
without use of an external voltage source. The current flow from
the spontaneous reaction is not controlled by external voltage in
this embodiment.
[0152] In another embodiment, however, the galvanic cell apparatus
comprises an external voltage source which is used to regulate the
oxidation reaction, and in another embodiment, the production of
carbon is carried out with use of an external voltage source to
regulate the oxidation reaction. This can also be called a "forced
current" embodiment. The application of an external voltage source
allows one to control the voltage over time using a controlled
voltage over time curve, including a step curve, for example.
Constant voltage and/or constant current regimes can be used. Over
time, voltage can be increased or decreased. Reaction rate can be
controlled and increased using the external voltage. For example,
reaction rate (current flow in amperage) might increase at least
ten times, or at least twenty times, or at least fifty times, or at
least 100 time, or at least 250 times, for example, with the
application of external voltage compared to cases with no external
voltage applied. The level of external voltage can be determined
for a particular system. One wants to avoid side reactions. One
often will want to increase reaction rate. Voltage can be, for
example, 0 V to 40 V, or 0 V to 30 V, or 0 V to 20 V, or 10 V to 20
V. The external voltage source can be applied with use of a
potentiostat as known in the art.
[0153] In one embodiment, the electrochemical cell apparatus is an
electrolytic cell apparatus. Here, the reaction is not spontaneous,
and an external voltage needs to be and is applied to drive the
reaction. An example is making lithium or sodium.
The Carbide Chemical Compound Starting Material
[0154] Carbide chemical compounds or "carbides" are known in the
art. See, for example, Cotton & Wilkinson, Advanced Inorganic
Chemistry, 4.sup.th Ed., 1980, pages 361-363. This text classifies
types of carbides as saltlike carbides, interstitial carbides, and
covalent carbides.
[0155] Known carbide chemical compounds include, for example,
aluminum, arsenic, beryllium, boron, calcium, chromium (in five
different Cr:C ratios), cobalt, hafniuim, iron seven different Fe:C
ratios), lanthanum, manganese (in two different Mn:C ratios),
magnesium (in two different Mg:C ratios), molybdenum (in three
different Mo:C ratios), nickel (in two different Ni:C ratios),
niobium (in two different Nb:C ratios), plutonium (in two different
Pu:C ratios), phosphorous, scandium, silicon, tantalum (in two
different Ta:C ratios), thorium (in two different Th:C ratios),
titanium, tungsten (in two different W:C ratios), uranium (in two
different U:C ratios), vanadium (in two different V:C ratios), and
zirconium carbide. Also, a carbide can form with two different
metals such as cobalt tungsten carbide.
[0156] In one embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. More
particularly, the carbide chemical compound is a salt-like carbide
in one embodiment. In another embodiment, the carbide chemical
compound is a methanide, an acetylide, or a sesquicarbide.
[0157] Methanides react with water to produce methane. Methane is a
carbon atom bonded to four hydrogen atoms in an sp3 hybridization.
Two examples of methanides are aluminum carbide (Al.sub.4C.sub.3)
and beryllium carbide (Be.sub.2C). Acetylides are salts of the
acetylide anion C.sub.2.sup.-2 and also have a triple bond between
the two carbon atoms. Triple bonded carbon has an sp1 hybridization
and two examples of acetylides are sodium carbide (Na.sub.2C.sub.2)
and calcium carbide (CaC.sub.2). Sesquicarbides contain the
polyatomic anion C.sub.3.sup.-4 and contains carbon atoms with an
sp1 hybridization. Two examples of sesquicarbides are magnesium
carbide (Mg.sub.2C.sub.3) and lithium carbide
(Li.sub.4C.sub.3).
[0158] Sesquicarbides are of particular use for the preparation of
sp1 carbon. One can produce Mg.sub.2C.sub.3 in the laboratory by
bubbling methane through molten magnesium metal under an inert
argon atmosphere at over 750.degree. C. Other hydrocarbons such as
pentane may also be viable candidates. Also, molten magnesium (Mg)
reaction is another area of chemistry where little has been
conducted. Research in molten Mg reactions have been limited
because of the dangers associated with molten Mg, especially with
the process generating hydrogen gas as well. But a process very
similar to the synthesis of the magnesium sesquicarbide can be used
to convert methane directly into carbon in the form of graphite and
hydrogen gas. Methane can be bubbled through a molten solution of
Mg and magnesium chloride salt. When heated to a temperature of
over 750.degree. C. under an argon atmosphere the elemental Mg
metal and MgCl.sub.2 both melt to form a liquid solution. Similar
to the Mg sesquacarbide synthesis, methane is bubbled through the
solution to produce either MgC.sub.2 (magnesium carbide) or
Mg.sub.2C.sub.3 and hydrogen gas that can be collected as a value
added product. The carbide then reacts with the metallic salt based
on the original chemistry of the carbon producing carbide reaction.
The Mg.sub.2C.sub.3 and MgCl.sub.2 are converted to elemental
carbon in the form of graphite, elemental Mg metal and MgCl.sub.2,
which would remain as part of the liquid solution. Therefore, the
Mg metal and MgCl.sub.2 salt would remain unchanged throughout the
overall process while the methane would be converted to pure carbon
and hydrogen gas.
[0159] In particular embodiments, the carbide chemical compound is
calcium carbide, aluminum carbide, sodium carbide, magnesium
carbide, lithium carbide, beryllium carbide, iron carbide, copper
carbide, and chromium carbide. Sodium carbide has the advantage of
being lighter.
[0160] In other more particular embodiments, the carbide chemical
compound is calcium carbide or aluminum carbide.
[0161] In another embodiment, the carbide chemical compound has
sufficient electronic conductivity to function as or in an anode.
The conductivity for different carbides can vary depending on
factors such as purity and temperature. However, one skilled in the
art for a particular application can determine whether there is
sufficient electronic conductivity and how to adapt the
conductivity for the need. For example, the carbide chemical
compound can have an electronic conductivity of at least 10.sup.-8
S/cm, or at least 10.sup.-7 S/cm, or at least 10.sup.-6 S/cm, or at
least 10.sup.-5 S/cm, or at least 10.sup.-4 S/cm, or at least
10.sup.-3 S/cm, or at least 10.sup.-2 S/cm, or at least 10.sup.-1
S/cm, or at least 10.sup.0 S/cm. The electronic conductivity of
calcium carbide provides a useful benchmark for sufficient
conductivity. No particular upper limit is present except for the
limits provided by nature for a particular carbide.
[0162] The form of the carbide chemical compound can also be
varied. For example, it can be used in particle form or it can be
used in the form of a monolithic material. In one embodiment, the
carbide chemical compound is in the form of individual pieces or
particles. In another embodiment, the carbide chemical compound is
in the form of individual pieces or particles having a size of less
than one cm. The mesh size of particles can be controlled.
[0163] The carbide chemical compound can be used in compositions
and mixed with other ingredients such as binders or conductivity
agents to the extent the desired reaction can be achieved. In some
embodiment, more than one carbide chemical compound can be
used.
[0164] One can use an electronically conductive binder to hold the
pieces or particles of carbide together. This can, for example,
increase the surface area of the carbide which is in direct contact
with a conductive surface. Electronically conductive binders also
can be selected as a way to produce composite materials where the
conductive properties and other characteristics of the binder can
be used to change the characteristics of elemental carbon material
produced. Examples of electronically conductive binders include
conjugated polymers in doped or undoped form such a polythiophene
or a polyaniline.
[0165] In one embodiment, the carbide is not silicon carbide.
[0166] Carbides are described further herein with respect to the
apparatus and the carbide electrode structure.
Temperature and Pressure
[0167] Relatively low temperatures, including room temperature, can
be used for the reaction to form carbon. For example, the
temperature can be, for example, about -50.degree. C. to about
100.degree. C., or about 10.degree. C. to about 90.degree. C., or
about 0.degree. C. to about 50.degree. C., or about 15.degree. C.
to about 50.degree. C. The temperature can be, for example, about
20.degree. C. to about 30.degree. C., or about 23.degree. C.,
24.degree. C., or 25.degree. C. In some embodiments, one will want
if possible to avoid the expense of cooling, heating, and
temperature control elements. In some embodiments, one will want to
run the reaction as close to ambient as possible. As known in the
art, in a larger manufacturing operation, excess heat from one
point in the operation can be transferred to another point in the
operation which needs heat.
[0168] In some embodiments, the methods described herein are
undertaken at room temperature.
[0169] The pressure can be about 1 atmosphere (760 torr) or normal
pressure. The pressure can be, for example, about 720 torr to about
800 torr. Alternatively, the pressure can be for example about 0.5
atmosphere to about 5 atmosphere, or about 0.9 atmosphere to about
1.1 atmosphere. In some embodiments, one will want if possible to
avoid the expense of using pressures below or above normal
atmospheric ambient pressure. One can use a higher pressure to
control the boiling point of the solvent. However, the equipment
must be adapted to sustain high or low pressures.
[0170] A preferred embodiment is that temperature and pressure both
are about ambient so than expensive methods to control temperature
and pressure are not needed. Hence, for example, the temperature
can be about 20.degree. C. to about 30.degree. C., or about
25.degree. C., and the pressure can be about 720 torr to about 800
tom or about 760 torr.
Other Method Parameters
[0171] In one embodiment, one or more materials used in the process
can be recycled. The material can be purified as part of the
recycling. For example, solvent can be distilled and recaptured for
further use. Salts can be recaptured and reused.
[0172] In another embodiment, the current flow from a process
reactor to make carbon which is run as a galvanic cell can be used
to help power another process reactor, including one used to make
elemental carbon material, in which current is needed to help
control the voltage.
[0173] The percent yield of the reaction for elemental carbon
material product can be controlled by the amount of current flow
and the methods of isolation as known in the art. Percent yield can
be measured with respect to the amount of carbon in the carbide
chemical compound put in the reactor. In some cases, the yield is
at least one percent, or at least 5%, or at least 10%, or at least
20%.
Organic Solvent Reaction to Produce Carbon from Carbide
[0174] A third aspect is provided for the production of elemental
carbon material at normal temperature and pressure but without an
electrochemical apparatus. Here, a method is provided comprising:
producing elemental carbon material from the oxidation of carbide
in at least one carbide chemical compound (e.g., calcium carbide)
which is in contact with a solution comprising at least one organic
solvent (e.g., methanol) and at least one dissolved salt (e.g.,
calcium chloride) comprising at least one metal cation which is
reduced. The cation is selected so that a spontaneous reaction can
occur wherein the carbide is oxidized and the metal cation is
reduced. However, in this embodiment, the molten salt approach of
U.S. application Ser. No. 14/213,533 and PCT Application
PCT/US2014/028755 and the electrochemical approach described herein
are not used. Rather, in this embodiment, the reaction can be
carried out in a single reaction container and need not be split
into two cells as is done with the electrochemical reaction.
[0175] In this embodiment, the temperature and pressure can be as
described above. Normal temperature and pressure can be used.
[0176] The carbide chemical compound can be as described herein
using, for example, aluminum carbide or calcium carbide. The
selection of salts, cations, and anions also can be made as
described herein.
[0177] Examples of the organic solvent include solvents listed
herein for the electrochemical reaction such as an alcohol such as
methanol or ethanol as described herein. Polar solvents are needed
which can dissolve a salt. A protic solvents can be used. Ideally,
the solvent would not react with carbide. Alternatively, it reacts
with carbide but only very slowly.
[0178] The elemental carbon material produced is described herein
also.
[0179] The reaction time can be adapted to the need.
[0180] Anhydrous reaction conditions can be used. For example, a
dry box can be used to avoid side reactions with water or
oxygen.
III. Apparatus
[0181] Another aspect provides for an apparatus which can be used
to carry out the methods described herein, including an apparatus
comprising at least one electrochemical cell comprising: at least
one anode comprising at least one carbide chemical compound, and at
least one cathode. This apparatus can be used to carry out the
methods described and/or claimed herein including those described
in Part II of this application. Again, carbide electrode structures
which can be used in the apparatus are described further in, for
example, Part IV of this application. Again, elemental carbon
material reaction products are described further in Part V of this
application. Other embodiments include methods of making these
apparatuses. A plurality of apparatuses can be used in a larger
system if desired.
[0182] The electrochemical apparatus can be a galvanic cell
apparatus or an electrolytic cell apparatus. The galvanic cell is
preferred.
[0183] In one embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. In
one embodiment, the carbide chemical compound is a salt-like
carbide. In one embodiment, the carbide chemical compound is a
methanide, an acetylide, or a sesquicarbide. In one embodiment, the
carbide chemical compound is calcium carbide, aluminum carbide,
sodium carbide, magnesium carbide, lithium carbide, beryllium
carbide, iron carbide, copper carbide, and chromium carbide. In one
embodiment, the carbide chemical compound is calcium carbide or
aluminum carbide. In one embodiment, the carbide chemical compound
has sufficient electronic conductivity to function as an anode. In
one embodiment, the carbide chemical compound has an electronic
conductivity of at least 10.sup.-8 Sian, or at least 10.sup.-7
S/cm, or at least 10.sup.-6 S/cm, or at least 10.sup.-5 S/cm, or at
least 10.sup.-4 S/cm, or at least 10.sup.-3 S/cm, or at least
10.sup.-2 S/cm, or at least 10.sup.-1 S/cm, or at least 10.sup.0
S/cm. The electronic conductivity of calcium carbide provides a
useful benchmark for sufficient conductivity. No particular upper
limit is present except for the limits provided by nature for a
particular carbide.
[0184] In one embodiment, the carbide chemical compound is in the
form of individual pieces or particles. In one embodiment, the
carbide chemical compound is in the form of individual pieces or
particles having a size of less than one cm.
[0185] In another embodiment, the carbide chemical compound is in
the form of an integral material or an ingot of material.
[0186] In one embodiment, the carbide chemical compound is held in
a container.
[0187] In one embodiment, the galvanic cell apparatus anode is
contacted with a solution comprising at least one solvent and at
least one salt.
[0188] In one embodiment, the electrochemical cell apparatus anode
is contacted with a solution comprising at least one organic
solvent and at least one dissolved salt, as described above. In one
embodiment, the electrochemical cell apparatus cathode is contacted
with a solution comprising at least one organic solvent and at
least one dissolved salt as described above. In one embodiment, the
electrochemical cell apparatus cathode is a metal cathode as
described above. In one embodiment, the electrochemical cell
apparatus cathode is a metal cathode, wherein the metal is zinc,
tin, iron, copper, or silver. In one embodiment, the
electrochemical cell apparatus cathode is a metal cathode, wherein
the metal is zinc or tin.
[0189] In one embodiment, the electrochemical cell apparatus
comprises an external voltage source to regulate an oxidation
reaction of carbide in the carbide chemical compound. For example,
a potentiostat can be used to provide such an external voltage
which can be varied.
[0190] Apparatus schematics are provided in FIGS. 2-5 and 19. FIGS.
17 and 18 show actual smaller scale apparatuses for carrying out
the reactions. FIGS. 20-23 show a larger apparatus and elements of
the apparatus.
[0191] There are several improvements to the reactor in FIG. 18
from the reactor of FIG. 17. The first is cells are slightly larger
allowing for greater volume of solvent and to accommodate to volume
occupied by the reference electrodes that can be added to the
various experiments. The addition of the ports on the sides of the
cell is also to accommodate the addition of various electrodes and
monitoring devices. The other improvements include the increased
diameter of the salt which to facilitate the greater transfer of
ions. Finally, the reactor was designed and fabricated in two
separate pieces held together by a glassware clamp. This allows an
ion exchange membrane to be installed in the salt bridge.
[0192] In one embodiment, the apparatus is adapted for carrying out
the methods described and/or claimed herein.
IV. The Carbide Electrode Structure and Methods of Use
[0193] The carbide chemical compound can be used in and adapted for
use in an electrode structure. Hence, yet another aspect provides
for an electrode structure comprising at least one carbide chemical
compound, wherein optionally the carbide chemical compound is a
salt-like carbide; and at least one electronically conductive
element different from the carbide chemical compound. This
electrode structure can be used to carry out the methods and to
prepare the apparatuses described and/or claimed herein.
Embodiments described herein also include methods of making and
methods of using the carbide electrode structure. Multiple
electrode structures can be used as part of a larger electrode
system. The shape of the electrode can be varied for the need. The
conductivity of the electrode can be adapted to the need. The solid
properties and macro-, micro-, and nano-scale morphology, such as
the size and shapes of openings, porosity, and pore size, can be
adapted to the need.
[0194] The solid electrode structure and the carbide chemical
compound can be contacted with at least one liquid for a redox
reaction. The electrode structure provides a reaction of the
carbide chemical compound which is not just a surface reaction but
can extend to the internal structure of the carbide chemical
compound. While the present inventions are not limited by theory,
it is believed that the carbon carbide layer of the carbon compound
at the surface is reacted to form elemental carbon material as the
cation (e.g, calcium) is transported away from the carbon into
solution. Multiple layers of carbon can be built up. The surface of
the carbide can have some porosity.
[0195] The carbide electrode can be an electrode (an anode) where
the chemical reaction can occur within the electrode instead of
just at the surface. The electrode material itself (e.g., calcium
carbide) is being consumed in the reaction where the calcium ion
dissolves into the solution and the elemental carbon material is
remaining.
[0196] In one embodiment, the carbide chemical compound is a
salt-like carbide or an intermediate transition metal carbide. In
one embodiment, the carbide chemical compound is a salt-like
carbide. In one embodiment, the carbide chemical compound is a
methanide, an acetylide, or a sesquicarbide.
[0197] In one embodiment, the carbide chemical compound is calcium
carbide, aluminum carbide, sodium carbide, magnesium carbide,
lithium carbide, beryllium carbide, iron carbide, copper carbide,
chromium carbide, and chromium carbide. In one embodiment, the
carbide chemical compound is calcium carbide, aluminum carbide,
sodium carbide, magnesium carbide, lithium carbide, or beryllium
carbide. In one embodiment, the carbide chemical compound is
calcium carbide or aluminum carbide. In one embodiment, the carbide
chemical compound has sufficient electronic conductivity to
function as an anode. In one embodiment, the carbide chemical
compound has an electronic conductivity of at least 10.sup.-8 S/cm
or other ranges described herein such as at least 10.sup.-7 S/cm,
or at least 10.sup.-6 S/cm, or at least 10.sup.-5 S/cm, or at least
10.sup.-4 S/cm, or at least 10.sup.-3 S/cm, or at least 10.sup.-2
S/cm, or at least 10.sup.-1 S/cm, or at least 10.sup.0 S/cm. No
particular upper limit is present except for the limits provided by
nature for a particular carbide. In one embodiment, the carbide
chemical compound is an ionically bonded solid.
[0198] In one embodiment, the carbide chemical compound is in the
form of individual pieces or particles. In one embodiment, the
carbide chemical compound is in the form of individual pieces or
particles having a size of less than one cm. In one embodiment, the
carbide chemical compound is produced in a form to provide maximum
or large amounts of surface area. This can facilitate reaction of
the carbide at its surface. The particle size and surface area can
be adapted to the multiple needs.
[0199] In one embodiment, the carbide chemical compound is a single
monolithic piece or a series of monolithic pieces. For example,
calcium carbide is typically formed in large ingots. The ingots are
then crushed and classified to the proper piece or particle size
before going out as final product. One can maintain the large
ingots to preserve the large crystals of calcium carbide produced.
This would in turn allow for large single sheets of graphene to be
produced using the electrochemical methods described herein.
[0200] In one embodiment, one can take the large ingot of calcium
carbide produced as one solid piece. One hole (or even several
holes) can be drilled or bored out where it can then be connected
to a current collector. The current collector can be, for example,
any metal with a melting point lower than the melting point of the
calcium carbide. Alternatively, metals with melting points higher
than that of calcium carbide can be used. However, these would
probably be specialized alloys to withstand those temperatures.
[0201] This metal would also be electrically conductive and
preferably inert in the solvent/salt combination used for the
reaction. A rod of the metal can be inserted into the whole board
out in the calcium carbide ingot. The rod would then be "welded" to
the single piece of calcium carbide by pouring a molten form of the
metal into the gap between the rod in the hole bored out in the
calcium carbide. The molten metal would act effectively as a weld
connecting the two. This is similar to how electrodes are made for
the aluminum industry.
[0202] A second method can be done by fabricating a structure like
a cage or something similar to tresses used in buildings. Any type
of shape or structure that includes empty space and provides a high
surface area can be used. The structure would be made out of a
conductive material that is stable at the temperatures of carbide
production or around 2000.degree. C. Another desired characteristic
would be that the material would be inert to the solvent/salt
solution used in the electrolysis reaction. Graphite can be an
ideal material for this application. Another possibility could be
some type of metal alloy that is stable to high temperatures. The
structure could then be placed into the ingot where the solid piece
of calcium carbide is formed. The calcium carbide would form around
the current collector. Then the calcium carbide formed and the
current collector can be removed as one single piece and used as
the carbide electrode.
[0203] In some embodiments, the carbide chemical compound can be
used with one or more additional, different materials such as an
additive. Materials and additives which are useful for making
electrodes can be used. For example, a binder can be used.
[0204] In one embodiment, the carbide chemical compound is held in
a container. In one embodiment, the container has openings which
allow fluid, such as an electrolyte, to enter the container and
contact the carbide chemical compound
[0205] In one embodiment, the carbide chemical compound is divided
into portions. In one embodiment, the carbide chemical compound is
divided into approximately equal portions.
[0206] In one embodiment, the carbide chemical compound is at least
about 80 wt. % pure, or at least 90 wt. % pure, or at least 95 wt.
% pure, or at least 97 wt. % pure.
[0207] The electronically conductive element should have good
electronic conductivity such as, for example, at least 10.sup.-3
S/cm, or at least 10.sup.-2 S/cm, or at least 10.sup.-1 S/cm, or at
least 10.sup.0 S/cm.
[0208] In one embodiment, the electronically conductive element is
a binder for the carbide chemical compound.
[0209] In one embodiment, the electronically conductive element is
adapted to be non-reactive with the reaction media. For example, it
should be inert to the contacting solution, or at least inert
enough to effectively conduct the reaction for the need.
[0210] In one embodiment, the electronically conductive element is
a container and the carbide chemical compound is held in the
container.
[0211] In one embodiment, the electronically conductive element is
a metallic container and the carbide chemical compound is held in
the metallic container. In one embodiment, the electronically
conductive element is a non-metallic container such as graphite and
the carbide chemical compound is held in the non-metallic container
such as graphite. For example, graphite baskets can be used.
[0212] In one embodiment, the electronically conductive element
comprises at least one conductive rod.
[0213] In one embodiment, the electrode structure is adapted to be
removably attached to an apparatus.
[0214] In one embodiment, the electronically conductive element of
the electrode structure comprises at least one current
collector.
[0215] In one embodiment, the electrode structure is adapted for
use as an anode in, for example, an electrochemical cell
apparatus.
[0216] For example, provided is a method comprising operating at
least one anode in an electrochemical cell, wherein the anode
comprises at least carbide chemical compound which includes a
method comprising operating at least one anode in a galvanic cell,
wherein the anode comprises at least carbide chemical compound. The
electrochemical cell apparatus can be a galvanic cell apparatus or
an electrolytic cell apparatus. The apparatus can be used for
production of elemental carbon material. However, other embodiments
are possible for uses other than the production of elemental carbon
material. Other uses of the apparatus with the carbide electrode
include oxidation reactions such as, for example, conversion of
aldehyde to carboxylic acid, and oxidation of a metal such as
ferrous ion to ferric ion. Such reactions could be useful in, for
example, environmental processes such as, for example, acid mine
drainage or sewage treatment.
[0217] In most cases, the one or more carbide chemical compounds is
the only electrochemically reactive moiety participating in the
oxidation part of the redox reaction. In one embodiment, the anode
electrochemically active material consists essentially of at least
one carbide chemical compound. In another embodiment, the anode
electrochemically active materials consist of at least one carbide
chemical compound. Here, a conductor such as a metal which is not
oxidized or reduced in the anode is not considered an
electrochemically active material.
V. The Elemental Carbon Material as Reaction Product
[0218] Still further, another aspect provides for an elemental
carbon material composition prepared by the methods, or with use of
the apparatuses or carbide electrode structures, described and/or
claimed herein. The elemental carbon material can be described
and/or claimed by the characteristics of the elemental carbon
material and/or by how it was made. Elemental carbon materials are
materials known in the art to focus on the carbon content and do
not include organic compounds such as methane, methanol, or acetic
acid. Examples such as graphite and diamond are well-known as
elemental carbon materials. These compositions can range from the
compositions as initially prepared from the carbide chemical
compound to the compositions as they exist after one or more
treatment, purification, and/or separation steps (post-processing
steps including exfoliation and doping steps, for example). The
compositions can be mixtures of different forms of the elemental
carbon material. The composition can comprise crystalline portions
and/or amorphous portions. The carbon can be in the form of one or
more graphene layers, and it can be in an exfoliated form.
Preferred embodiments for graphene include atomically thin single
sheet graphene or few layer graphene. Graphene can have 1-10 layers
for example. Thicker for ins of graphene also can be of interest.
Also, the elemental graphene material, including graphene forms,
can be disposed on substrate films.
[0219] Characterization methods for elemental carbon materials are
well known and include analysis of microstructure, morphology, and
physical properties. For example, carbon black materials are well
known and characterized as described in, for example, (1) Carbon
Black: Production, Properties, and Uses (Sanders et al., Eds.), and
(2) Carbon Black: Science and Technology, 2.sup.nd Ed., (Donnet et
al., Eds.) 1993. Morphological properties of elemental carbon
materials include, for example, particle size, surface area,
porosity, aggregate size, and aggregate shape. Physical properties
include density, electronic, thermal, bulk, and impurities.
Microstructure analysis includes XRD, Dark Field Electron
Microscopy, Oxidation Studies, Diffracted Beam Electron Microscopy,
Phase Contrast TEM imaging, and High Resolution SEM, STEM, STM,
SFM, and AFM imaging.
[0220] Other characterization methods for carbon are known and
described further herein. See, for example, review article by Chu
et al., Materials Chemistry and Physics, 96 (2006), 253-277, which
describes characterization of amorphous and nanocrystalline carbon
films. Methods described include optical (Raman, both visible and
UV, and IR), electron spectroscopy and microscopy (e.g., XPS, AES,
TEM of various kinds, and EELS), surface morphology (AFM, SEM),
NMR, and X-ray relectivity. Methods described include how to
measure sp2:sp3 ratios.
[0221] The elemental carbon material can provide many novel,
interesting, and useful structures when viewed under an SEM,
including at a 200 micron scale bar view or less as shown in the
Figures. Features shown in the SEM figures can be used to describe
and claim the elemental carbon materials. Spots on the elemental
carbon material also can be selected for Raman spectroscopy, and
Raman data can also be used to describe and claim the elemental
carbon materials. Other data such as EDAX and XRD can also be used
to describe and claim the elemental carbon materials.
[0222] Generally, high purity elemental carbon materials are
desired. In one embodiment, the elemental carbon material is more
than 70%, or more than 80%, or more than 90%, or more than 95%, or
more than 98%, or more than 99% (atomic percentage) carbon. This
percentage can be measured by, for example, elemental analysis
methods including SEM-EDAX. Of course, in some embodiments, less
high purity may be acceptable. Also, in some embodiments,
non-carbon elements can be deliberately incorporated such as in a
doping process.
[0223] In one embodiment, the elemental carbon material is more
than 50%, or more than 60%, or more than 70%, or more than 80%, or
more than 90% sp2 carbon. A combination of analytical techniques
can be used to determine an accurate estimate. For example, there
is also the possibility of analysis using bromine. Sp2 carbon
absorbs a certain amount of bromine relative to amorphous carbon or
even possibly sp1 carbon if we can produce it. Sp3 carbon does not
absorb bromine at all. Therefore, we may be able to quantitatively
determine these percentages using a type of bromine absorption
test.
[0224] In one embodiment, the elemental carbon material is more
than 50%, or more than 60%, or more than 70%, or more than 80%, or
more than 90% sp3 carbon.
[0225] In one embodiment, the elemental carbon material comprises
two-dimensional plate-like structures. These structures can be
stacked on top of one another. In another embodiment, the elemental
carbon material comprises three-dimensional structures.
[0226] In some embodiments, the elemental carbon material has
amorphous carbon content. In other cases, crystalline carbon can be
present.
[0227] In some cases, particles can be isolated, and average
particle size (d.sub.50) can be, for example, 500 nm to 500
microns, or one micron to 100 microns, or two microns to 50
microns, or 10 microns to 30 microns. If desired, nanoscopic
particles can be isolated with average particle size of less than
500 nm such as, for example, 10 nm to 500 nm, or 20 nm to 100 nm.
Commercial particle size analyzers can be used to measure particle
size.
[0228] The elemental carbon material, at various stages of
purification and isolation, can be tested by methods known in the
art including, for example, optical microscopy, electron microscopy
including scanning electron microscopy (SEM) and transmission
electron microscopy (TEM), energy dispersive x-ray analysis (EDX),
Raman and FTIR spectroscopy, x-ray diffraction, X-ray photoelectron
spectroscopy (XPS), Auger electron spectroscopy (AES), low energy
and high energy electron energy loss spectroscopy (EELS), neutron
scattering, ellipsometry, electrical resistance, and atomic force
microscopy (AFM). Particle analysis can also be carried out
including measurement of particle size and surface area.
Electrochemical testing can also be carried out. Tribology, wear,
friction, indentation, modulus, hardness testing can also be
carried out.
[0229] For Raman spectroscopy, a G band (around 1590 cm.sup.-1) can
be present in crystalline graphite and a D band (around 1345
cm.sup.-1) can be present associated with disordered graphite. The
ratio of the two bands can be used to characterize the degree of
graphitization and the graphite crystallite size.
[0230] The elemental carbon material produced can be analyzed by
surface analytical methods such as AFM or XPS. For example, XPS
analysis can show higher levels of oxygen at the surface than in
the bulk material. This can mean that the surface of the material
had formed graphene oxide. Graphene oxide, in principle, could be
formed as part of the reaction or due to the separation and
purification operations. Other surface elements can include O, H,
N, S, and halogens.
[0231] In another embodiment, the elemental carbon material
comprises sp1 carbon material.
[0232] In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that is C.sub.70. In some
embodiments, the methods can be used to produce an allotrope of
carbon that is C.sub.60. Other kinds of fullerenes can be made. In
some embodiments, the methods described herein can be used to
produce an allotrope of carbon that is Herringbone Multi Wall
Carbon Nano Tubes ("MWCNT"). Single-walled carbon nanotubes also
can be made. In some embodiments, the methods described herein can
be used to produce an allotrope of carbon that is Cylindrical
MWCNT. In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that comprises carbon
fibers.
[0233] The methods described herein can produce carbon with
sp.sup.1, sp.sup.2, and/or sp.sup.3 hybridization, as well as
mixtures thereof. The sp.sup.1 hybridized carbon can be in the form
of carbyne. The sp.sup.2 hybridized carbon can be in the form of
carbene, graphite, and/or graphene. The sp.sup.3 hybridized carbon
can be in the form of diamond.
[0234] Particular carbon materials may thus be produced through the
application of external voltage to an electrolysis cell wherein at
least one of the electrodes is a carbide.
[0235] In some embodiments, the methods described herein can be
used to produce an allotrope of carbon that is sp.sup.2 hybridized,
and contains no sp.sup.3 hybridization. In some embodiments, the
methods described herein produce an allotrope of carbon that is
sp.sup.3 hybridized, and contains no sp.sup.2 hybridization. In
some embodiments, the methods described herein produce an allotrope
of carbon that is sp.sup.1 hybridized and contains neither sp.sup.2
or sp.sup.3 hybridization.
[0236] In some cases, the elemental carbon material can have more
sp2 than sp3 hybridized carbons, and in other cases, the elemental
carbon material can have more sp3 than sp2 hybridized carbons. The
ratio of sp2:sp3 can be, for example, 1:10 to 10:1, or 1:8 to 8:1,
or 1:6 to 6:1, or 1:4 to 4:1, or 1:2 to 2:1.
[0237] The methods described herein can be used to produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.1 hybridized.
[0238] In an embodiment, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.2 hybridized.
[0239] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.1 hybridized.
[0240] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.2 hybridized in the form
of graphite.
[0241] In some embodiments, the methods described herein produce a
product that is more than 50%, more than 55%, more than 60%, more
than 65%, more than 70%, more than 75%, more than 80%, more than
85%, more than 90%, more than 95% sp.sup.3 hybridized in the form
of diamond.
[0242] Large area pieces of carbon, having high levels of elemental
carbon purity, are of particular interest. They can be, for
example, a source for large area graphene. The piece may have a
lateral dimension of, for example, at least one mm, or at least two
mm, or at least one cm, or at least two cm. The lateral dimension
can be a length or a width of a piece or particle. In some cases,
both the length and the width can be at least 1 mm, or at least 2
mm, or at least 1 cm, or at least two cm. The volume of the piece
can be, for example, at least one cubic mm, or at least one cubic
cm (cc), or at least 8 cubic cm (cc). Also important are forms of
carbon having flat surfaces whether of lower or higher flat surface
area.
[0243] Carbon structures are shown in the SEM and optical
photographs provided herein which can be of commercial use. In many
cases, it is desired to have crystalline forms of the elemental
carbon material rather than amorphous forms.
[0244] In some embodiments, the elemental carbon material comprises
at least some two-dimensional plate-like structures. In some
embodiments, the elemental carbon material comprises at least some
two-dimensional plate-like structures stacked on top of one
another. Graphene structures may be evident. Thicker graphene
structures can be converted to thinner graphene structures. In some
embodiments, the elemental carbon material comprises at least some
three-dimensional structures.
[0245] In some embodiments, the elemental carbon material shows
porous structures or voids.
[0246] In some embodiments, bent structures can be seen. The bent
structure can be characterized by an acute angle, and the angle can
be controlled by the synthesis method. In other embodiments, rods
can be formed. In some embodiments, curved elemental particles can
be observed. In some embodiments, perpendicular features can be
observed.
[0247] Further structures can be observed with higher resolution
analytical methods.
VI. Post Reaction Processing of Elemental Carbon Material
[0248] After forming in the apparatus, the elemental carbon
material can be further treated beginning with, for example,
purification and/or mechanically changing the form into powder or
particle forms. Treatments can be mechanical or chemical. The piece
of product can be subjected to various mechanical steps such as
grinding, exfoliation, or polishing steps. Additional treatment
steps can include, for example, doping and intercalation steps.
Some of the elemental carbon material may be attached to the
electrode and will need to be removed from the electrode. Other
elemental carbon material may leave the electrode during the
reaction and may, for example, sink to the bottom of the reaction
cell for collection.
[0249] PCT Application PCT/US2014/028755, filed Mar. 14, 2014 and
published as WO 2014/144374, also describes a method of making
carbon from carbide and metal salts in a thermal process, and also
describes various post reaction processing steps which can be
used.
[0250] In another embodiment, the elemental carbon material is
removed and treated with acid and washed or flushed with water.
Strong acids such as HCl can be used.
[0251] In one embodiment, the elemental carbon material can be
converted to particle form, and the particles separated based on
particle size.
[0252] Graphene exfoliation steps are known in the art and
described in, for example, Bonaccorso et al., Materials Today,
December 2012, 15, 12, 564. In particular, large area graphene
sheet production is of interest. The large pieces of elemental
carbon material produced by methods described herein can enable
production of large area graphene. A solvent such as NMP can be
used for exfoliation. Sonication can also be used for exfoliation.
Larger pieces of carbon in many cases require higher power to
exfoliate. The exfoliation process can be controlled so as to
control the thickness of the exfoliated product, such as
graphene.
[0253] Also described herein are derivative compositions associated
with the elemental carbon material compositions described herein.
For example, the elemental carbon material compositions described
herein can be mixed with or doped with other elements, compounds,
ingredients, additives, and/or materials.
VII. Applications
[0254] Selected representative examples of applications are
described below. Devices, apparatuses, systems, kits, methods of
making, and methods of using that are associated with these
applications are also described herein including devices,
apparatuses, systems, and kits which comprise the elemental carbon
materials and their derivatives described herein (e.g., battery,
fuel cell, or filtration devices). The elemental carbon reaction
products, whether in bulk form, microscale form, or nanoscale form,
can be used in a wide-variety of applications including, for
example, applications generally known for carbon materials
including applications known, more specifically, for graphite
materials, applications known for diamond materials, applications
known for amorphous carbon, and applications known for nanoscale
forms of carbon, for example. In some cases, the elemental carbon
material can be mixed with one or more other ingredients for
application use.
[0255] Carbon black, for example, is used as filler, pigment,
toners, and reinforcement agent.
[0256] Many applications relate to the electrically conductive
properties of carbon and the electronics and semiconductor
industries. For example, carbon inks are known including conductive
inks Carbon-based fillers or conductive agents are known.
[0257] Activated carbon has many applications.
[0258] Graphite is a material found in nature and also is
synthetically produced. Examples of natural graphite are flake,
crystalline, and amorphous graphite. Graphite flakes can have flat,
plate-like particles with hexagonal or angular edges. The percent
carbon can impact the application. Graphite can be used as
electrodes, pastes, brushes, crucibles, lubricants, foundry
facings, moderator bricks in atomic reactors, paints, pencils,
brake linings, foundry operations, refractory applications, steel
making, lithium-ion batteries, fuel cells, and the like.
[0259] In particular, batteries including lithium and lithium-ion
batteries can be an application, as well as air batteries such as
zinc air batteries. Lithium-ion batteries are described in, for
example, Yoshio et al. (Eds.), Lithium-Ion Batteries: Science and
Technologies, including chapter 3 (pages 49-73) and chapter 18
(pages 329-341) which focus on carbon anode materials, as well as
chapter 5 (pages 117-154) which focuses on carbon-conductive
additives and chapter 22 (pages 427-433) which focuses on novel
hard-carbon materials.
[0260] Graphene can be used in advanced semiconductor devices.
Large area graphene is important. Other applications include
filters (including water filtration and desalinization of sea
water), batteries, touch screens, capacitors, fuel cells, sensors,
high frequency circuits, flexible electronics, computing, data
storage, solar, and photovoltaics.
[0261] Diamonds can be low quality or high quality and are applied
in applications which use hardness including abrasion resistant
materials, as well as drilling, polishing, and cutting materials.
Diamonds also can be used for sensors, electronics, medical
imaging, semiconductors, super computers, and sonar. Diamonds also
can be gems.
[0262] Carbon related materials such as CaC.sub.6 have been shown
to be superconducting. Other applications for sp1 materials relate
to use of superconductor materials and even high temperature or
room temperature superconductor materials.
[0263] Carbon nanotube products can be in the form of "forests" of
microscopic tubular structures. They can be used in, for example,
baseball bats, aerospace wiring, combat body armor, computer logic
components, and microsensors in biomedical applications. Carbon
nanotubes also can be used in lithium ion batteries and various
sporting equipment.
PREFERRED EMBODIMENTS AND WORKING EXAMPLES
[0264] In an illustrative embodiment, an electrode in an
electrochemical cell comprises or is comprised of calcium carbide
and is immersed in a solution of methanol and calcium chloride
salt. As the carbide electrode is an ionic solid which is
electrically conductive, the carbide electrode allows for the
oxidation of the acetylide anion to occur in the solid state. As a
counter cell, a polished piece of zinc is immersed in a solution of
zinc chloride in methanol. Alternatively, because the reduction
potential of tin is higher than the reduction potential of zinc, in
an aspect, elemental tin in a stannous chloride solution can be
utilized instead of zinc in zinc chloride. When an electrical
connection is established between the cells through a salt bridge,
the oxidation of carbide anion reaction and the reduction of zinc
cation reaction can occur at room temperature. Thus, the voltage of
the reaction can be directly read.
[0265] The galvanic reaction apparatus of preferred embodiments
differs from a conventional galvanic apparatus in several respects.
First, the zinc electrode is the cathode in the process while the
carbide electrode is the anode. At the cathode, the Zn.sup.2+ ions
from the ZnCl.sub.2 in solution are reduced (gain electrons) to
elemental zinc which plates out on the surface of the zinc
electrode. The Cl.sup.- ions from the ZnCl.sub.2 in solution are
the counter ions that migrate across the salt bridge to balance the
charge from the flow of electrons. At the anode in the carbide
cell, the C.sub.2.sup.2- from the solid calcium carbide is oxidized
(loses electrons) to form elemental carbon and the Ca.sup.2+ ions
enter the solution inside the carbide cell.
[0266] In exemplary embodiment of the electrolysis apparatus of the
invention, calcium carbide loaded into stainless steel baskets
forms the anode in the carbide cell. The stainless steel rod and
baskets which hold the calcium carbide are essentially an extension
of the wire connecting the cathode and the anode.
[0267] The resulting apparatus is unique in that the calcium
carbide is an ionic solid which is electrically conductive.
Therefore, the oxidation reaction is believed to occur in the solid
phase where the carbide anion (C.sub.2.sup.2-) is oxidized to
elemental carbon. This is substantially different from a reaction
in which the anions are oxidized in the liquid phase from the
solution. In addition, the Ca.sup.2+ ions entering the solution are
unchanged (not oxidized) from their state in the solid phase.
[0268] For verification, in a preferred embodiment, the voltage of
a standard silver/silver chloride cell to the zinc/zinc chloride
cell is compared using a salt bridge. In an embodiment, the salt
bridge is a saturated calcium chloride solution in methanol. This
permits migration of the chloride to the silver/silver chloride
cell and calcium ions to the zinc/zinc chloride cell needed to
maintain electro neutrality. The voltage of the silver/silver
chloride cell is subtracted from the cell voltage to yield the
zinc/zinc chloride potential. Once the potential is known, the
potential of the calcium carbide cell can be determined. Since the
products of the carbide cell are not mixed with any
non-water-soluble material, they can be cleaned and the products
analyzed.
[0269] This can help to provide a method to determine the voltage
necessary to produce a specific product.
[0270] In an embodiment, an electrochemical cell enables the
production of the entire range of carbon materials in their various
states.
[0271] In an embodiment, an electrochemical cell as described
herein includes (1) an electrode, for example a solid electrode,
(2) a conductor, for example a conductor in a lower or elemental
valence state; and (3) an electrode, for example an electrode
immersed in a solution that contains ions of the electrode
material. The solution is conductive. That is, the ions can be
mobile and can migrate under the influence of an electrical
potential.
[0272] The Latimer series is a compilation of the electrochemical
potentials between the metal and a standard solution of its ions in
the conducting solution. Two such cells with different
electrochemical potentials can be used to make either an
electrolytic or a galvanic apparatus; one cell is oxidizing, losing
electrons and the other cell is reducing, gaining electrons. If the
cell is reducing, then electrons from the opposite cell, the
oxidizing cell, accumulate on the electrode surface. Positive ions
from the solution migrate to the electrode and electrons are picked
up by the ions that are subsequently reduced sometime to the
elemental state where they plate out on the electrode surface. If
the cell is oxidizing, electrons leave the electrode and go to the
reducing electrode. The material on the oxidizing electrode
dissolves into the solution as positive ions.
[0273] In the carbide cell, the carbon anion in the calcium carbide
can give up electrons and become elemental carbon. The calcium
cation can dissolve in the solvent and requires anions to be
dissolved in the solvent. The electrons from the carbide anion will
pass through the circuit to the metal electrode in the reduction
cell. This will attract cations of the metal from the solution and
as they receive the electrons from the anion oxidation they will be
reduced and plated out on the metallic electrode. This provides an
abundance of anions that fulfill the deficit needed by the calcium
ion in the other cell. A salt bridge is used to balance the cations
and anions in the apparatus. The salt bridge is a connection of a
salt solution to both cells. The anions from the salt bridge travel
to the oxidizing electrode while the cations from the salt bridge
travel to the reducing electrode. The difference in electrode
potentials drives the cell.
[0274] A galvanic cell, such as that represented in FIG. 2, depends
on the voltage potential from the chemical reaction to cause
electron flow. A cell, like that shown in FIG. 3, may use an
external power source, such as a battery or potentiostat, to drive
or regulate the chemical reactions. The exact potential can be
controlled by an external variable resister but is limited by the
range of reactions than can occur in the cells. The application of
the different potentials can determine the products produced by
controlling the chemistry that can occur in the cells as chemical
reactions are a limited by the potential.
[0275] Under such a system, the voltage can be adjusted through the
variable resister to any desired voltage within the available
potential. The current can be permitted to flow until an
appropriate quantity of product is produced in the carbide cell for
isolation and analysis. The voltage can be altered until another
current flows and the procedure can be repeated until all the
various materials have been isolated and tested. In an embodiment,
the zinc cell voltage is measured against the standard
silver/silver chloride cell, and also monitored.
[0276] The calcium chloride or other associated salt is soluble in
the solvent and the solution is conductive to produce the oxidative
cell. The oxidative cell may then be attached to a second cell, the
reducing cell, though a salt bridge. The salt bridge may be made
from the same solvent and saturated with the same calcium salt or
another suitable salt. In another embodiment, the reducing cell
contains an elemental metal as an electrode immersed in a salt
solution of that metal as a cation in the same solvent.
[0277] As demonstrated by the Examples described below, the
specific allotropes produced using the apparatus of the invention
vary depending on the voltage potential between the cells of the
apparatus. In the electrolytic cells according to some embodiments
of the invention, one electrode is connected to a voltmeter and one
end of a power supply and the other electrode is attached to a
variable resister. The second arm of the power supply is attached
to the variable resister so the resister can control the voltage
between the two-electrode cell circuits. Thus, the circuit can
permit any voltage, and therefore any potential. This allows the
production of particular desired allotropes and the maintenance of
a particular voltage level to enhance the purity of a particular
allotrope.
[0278] In some embodiments, the methods described herein can be
undertaken using a galvanic cell reactor. The reactor can be
comprised of multiple parts, including a carbide cell and a zinc
cell. In some embodiments, the reactor comprises a carbide
electrode. In some embodiments, the carbide cell and the zinc cell
are connected by a salt bridge. The carbide cell can comprise
electrode baskets, which can contain the salt-like carbide. The
electrode baskets can comprise fine mesh (20-60 mesh) stainless
steel screens. The salt-like carbide in the electrode baskets can
then be immersed in a solution comprising a chloride salt. The
carbide cell can be connected to a circulation pump, which can draw
the solution from below the level of the electrode and salt bridge
and pumps it back into the top of the carbide cell, creating a flow
of the solution vertically in the cell. An inert gas (e.g. argon)
can be input near the bottom of the carbide cell, bubbled through
the solution, and removed from the carbide cell through the vapor
trap. The inert gas flow can maintain an inert environment inside
of the cell and generates additional agitation between the carbide
and the solution.
[0279] In some embodiments, the zinc cell comprises a zinc
electrode immersed in a solution of zinc chloride dissolved in the
solvent (dried methanol). The zinc electrode can include a rod of
elemental zinc. Attached to the zinc rod may be a basket filled
with mossy zinc (i.e., irregular pieces of elemental zinc) wherein
the rod can pass through the middle of the basket and allow the
mossy zinc to be in contact with the zinc rod. The zinc cell can be
connected to a circulation pump that draws the solution from below
the level of the zinc electrode and salt bridge and pumps it back
into the top of the cell above the basket containing the mossy
zinc. In addition, the argon enters at the very bottom of the cell
and bubbles through any precipitated zinc chloride to maintain the
saturation point in the solution.
[0280] The carbide cell and zinc cell can be connected by a salt
bridge, which can facilitate the flow of chloride ions from the
zinc cell to the carbide cell. The salt bridge can be comprised of
two isolation valves at either end, as well as a coupling which can
hold an ion exchange membrane, and a vent valve.
[0281] In some embodiments, the galvanic cell comprises an external
power supply.
[0282] The examples that follow demonstrate the use of reactions
having different voltage potentials to produce different carbon
allotropes and forms of the elemental carbon material.
Working Examples
[0283] Additional embodiments are provided by the following
non-limiting working examples.
Example 1--CaC.sub.2+ZnCl.sub.2.fwdarw.CaCl.sub.2+Zn+C
[0284] An apparatus was constructed that included two glass cells
connected by a glass tube. Along the glass connecting tube was a
valve to isolate the two cells from one another and a glass fritted
filter to prevent any solid material from migrating between the
cells. Each cell was roughly two inches in diameter and six inches
high. The glass tube connecting the cells was about 3 inches from
the bottom or about in the middle of the vertical height of the
cells. The cells also had a flat a bottom so that they could rest
on magnetic stirring plates to provide agitation during the
experiment.
[0285] Each cell was sealed with a glass cap using a glass ground
joint and each cap allowed for a 1/4 inch tube to pass through the
cap and extend into the cell. One of the cell caps was equipped
with an elemental metal electrode (e.g., zinc or tin), while the
second cell was equipped with an electrode which contains the
carbide.
[0286] The caps for each cell were fabricated with a glass nipple
roughly 5/16 in diameter. This permitted the elemental metal
electrode from passing through the Into the cell. A 12 inch long,
1/4 inch diameter elemental zinc rod was passed through the nipple
on the cap of the metal cell. A piece of Tygon tubing was slid over
the top of the elemental zinc rod down to where it also covered a
portion of the glass nipple in the cap. One hose clamp was placed
around the Tygon tubing covering the nipple while another hose
clamp was tightened on the Tygon tubing covering the elemental zinc
rod. This was done in order to seal the cell and maintain an inert
environment in the cell.
[0287] The carbide electrode was a hollow stainless steel mesh
sphere with a diameter of 1 and 5/8 inches connected to a stainless
steel tube. A small hole was drilled in the side of the stainless
steel tube within the cell to vent any vapors produced in the
experiment. The other end of the tube that was outside of the cell
was connected to a valve using flexible Tygon tubing which was
further connected to bubbler filled with methanol to prevent any
oxygen or moisture from entering the cell.
[0288] The cells were prepared in the controlled environment of a
glove box, free of oxygen and moisture. Several hundred milliliters
of dried methanol was prepared by removing the moisture dissolved
in the methanol using a molecular sieve. A magnetic stir bar was
placed in each cell of the apparatus and the valve on the tube
connecting the two cell was closed to isolate one cell from the
other.
[0289] The first cell was filled with the dried methanol to a
height of four inches or one inch above the connecting tube. Zinc
chloride anhydrous salt (ZnCl.sub.2) was stirred into the dried
methanol until the solution was saturated. The cell cap, which was
fitted with a 1/4'' diameter elemental zinc rod was set in place
using vacuum grease on the ground glass joint to seal the zinc
cell. The bottom of the elemental zinc electrode was immersed in
the ZnCl.sub.2/methanol solution.
[0290] The second cell was also filled with the dried methanol to
height of four inches or one inch above the connecting tube.
Calcium chloride anhydrous salt (CaCl.sub.2) was stirred into the
dried methanol until the solution was saturated.
[0291] The calcium carbide (CaC.sub.2) was then prepared by
reducing the particle size of the of the individual pieces to a
size of less than one centimeter. For this example, the calcium
carbide was ground and crushed to a particle size between 3.5 and
14 mesh. Calcium carbide was purchased from Acros Organics and the
product name was Calcium Carbide, 97+% (CAS: 75-20-7 and Codc:
389790025). The calcium carbide was not treated or purified before
start of the experiment.
[0292] The CaC.sub.2 was then sealed in the hollow stainless steel
mesh sphere of the carbide electrode which had been fitted into the
second cell cap. The carbide cell cap was set in place using vacuum
grease on the ground glass joint to seal the carbide cell. The mesh
sphere containing the calcium carbide was completely immersed in
the CaCl.sub.2/methanol solution. Tygon tubing was connected to the
opened end of the stainless steel tubing on the carbide electrode.
A pinch valve was used to completely seal the carbide cell from the
environment.
[0293] The connected cells, which had been sealed and isolated from
the environment, were removed from the controlled atmosphere glove
box. The connected cells were set in place with the bottom of each
cell resting on a separate magnetic stirring plate. The Tygon
tubing connected to the top of the stainless steel tube of the
carbide electrode was connected to the valve which was further
connected to the vapor bubbler filled with methanol. The pinch
valve on the Tygon tubing was then opened to the carbide cell. One
side of a multimeter was connected to the zinc electrode and the
other side was connected to the carbide electrode allowing for the
flow of electrons across the cells. The multimeter also permitted
the voltage and current between the two cell to be measured.
[0294] The reaction took place at room temperature, which was
estimated to be about 23.degree. C.-24.degree. C.
[0295] The vent valve was opened between the carbide electrode and
the vapor bubbler to allow any vapor produced to exit the carbide
cell. Next, both magnetic stir plates were turned on to agitate the
solution in each of the cells. Finally, the valve on the glass tube
connecting the cells was opened to allow for ions to flow between
the two cells. The voltage and current were measured using the
multimeter to ensure that the reaction was indeed proceeding.
[0296] After a period of time, the reaction was stopped by closing
the valve on the tube connecting the two cells.
[0297] The reaction time for Example One was about 28 hours.
[0298] The multimeter was disconnected along with the Tygon tubing
attached to the carbide electrode.
[0299] The carbide cell cap was removed along with the mesh
stainless steel sphere containing the products of the
experiment.
[0300] For describing the reaction products, two groups of products
are noted. The first group is the product that remained inside the
mesh electrode ("primary product"), and the second is the product
that escaped the mesh electrode and was resting at the bottom of
the glass cell ("secondary product"). The primary and secondary
products can be evaluated separately or they can be mixed and
evaluated together in a mixture.
[0301] The products of the experiment were then removed from the
mesh stainless steel sphere and treated with 6.0 molar hydrochloric
acid (HCl) and then flushed several times with distilled water.
[0302] The product at the bottom of the glass cells was the only
product visible prior to removal from the cell. In the cell
immersed in the solution, the product at the bottom of the cell
appeared to be an off-white colored gel. Small solid particles
which were darker in color could be seen in the gel-like material.
The first step in removing the product from the apparatus was to
remove the glass cap with the mesh stainless steel ball or carbide
of holder from the cell. The holder was opened up and its contents
transferred to a 600 mL beaker filled with a one molar HCl
solution. The contents of the holder had an appearance of a light
gray wet sand. The materials were transferred using a scapula. The
remaining residual material was removed from the stainless steel
holder using a spray bottle filled with the one molar HCl solution.
The contents are also collected in the same 600 mL beaker. The cell
was emptied by first decanting off the supernatant solution. The
remaining solution along with the products at the bottom of the
cell were poured into the 600 mm beaker containing the products
from the stainless steel holder. The remaining residual material in
the bottom of the cell was sprayed out into the 600 mm beaker using
the spray bottle containing the one molar HCl solution.
[0303] After treatment with water and HCl the products had the
appearance of a fine gray powder, or more particularly, a darker
gray powder.
[0304] The products of the experiment were confirmed to be only
elemental carbon using standard analytical methods including SEM
and EDAX. The atomic percent carbon was at least 98%.
[0305] A reaction product called "Sample A" is characterized in
FIGS. 8-11. The elemental carbon produced from the reaction
described herein using zinc included mainly two-dimensional carbon
sheet or plates stacked on top of one another which showed that the
carbon was sp.sup.2 hybridized. FIG. 8 (50 micron scale bar) shows
what the bulk material produced looks like, while FIGS. 9-11 are
"zoomed in" portions of FIG. 8 (scale bars of five or two microns),
to provide more definitive images of the plate-like structure of
the products.
[0306] The most striking difference between the SEM images from
this Example 1 reaction product compared to the reaction product of
the elemental carbon materials prepared by the thermal methods of
PCT/US2014/028755 was in the concentration of the amorphous carbon
produced. In this thermal method, much of the elemental carbon
material product was of an amorphous nature, and it was difficult
to see many interesting particles of interest. See, for example,
FIGS. 6 and 7. In the present Example 1, in contrast, it was
immediately striking the amount of non-amorphous carbon in the
sample with many interesting particles of interest.
[0307] Another important difference is that in PCT/US2014/028755,
the reaction of calcium carbide and zinc chloride was carried out
at 425.degree. C., a much higher temperature.
[0308] FIG. 17 shows the apparatus used in Example 1.
[0309] For product yield, 27.0 g of calcium carbide was added to
the holder to begin the experiment. Roughly 0.9 g of elemental
carbon materials was recovered as a product. This amount of
recovery was expected as the reaction was not allowed to proceed to
completion. However, the objective was met to show that elemental
carbon material was produced using the galvanic method at room
temperature and pressure.
[0310] In Example 1, the average voltage was about 20 mV and the
average current varied between about 0.5 and about 2.0 .mu.A. Other
than fluctuating continuously, there was no real change in voltage
and current over the course of the reaction.
Example 2--CaC.sub.2+SnCl.sub.2.fwdarw.CaCl.sub.2+Sn+C
[0311] For Example 2, which was based on tin chloride and tin
rather than zinc chloride and zinc, the apparatus was assembled in
the manner described in Example 1.
[0312] The cells were prepared in the controlled environment of a
glove box, free of oxygen and moisture. Several hundred milliliters
of dried methanol were prepared by removing the moisture dissolved
in the methanol using a molecular sieve. A magnetic stir bar was
placed in each cell of the apparatus and the valve on the tube
connecting the two cell was closed to isolate one cell from the
other.
[0313] The first cell was filled with the dried methanol to a
height of four inches or one inch above the connecting tube.
Stannous chloride anhydrous salt (SnCl.sub.2) was stirred into the
dried methanol until the solution was saturated. The cell cap,
which had been fitted with a 1/4'' diameter elemental tin rod, was
set in place using vacuum grease on the ground glass joint to seal
the zinc cell. The bottom of the elemental tin electrode was
immersed in the SnCl.sub.2/methanol solution.
[0314] The second cell was also filled with the dried methanol to
height of four inches or one inch above the connecting tube.
Calcium chloride anhydrous salt (CaCl.sub.2) was stirred into the
dried methanol until the solution was saturated. The calcium
carbide (CaC.sub.2) was then prepared by reducing the particle size
of the of the individual pieces to a size of less than one
centimeter. The CaC.sub.2 was then sealed in the hollow stainless
steel mesh sphere of the carbide electrode which had been fitted
into the second cell cap. The carbide cell cap was set in place
using vacuum grease on the ground glass joint to seal the carbide
cell. The mesh sphere containing the calcium carbide was completely
immersed in the CaCl.sub.2/methanol solution. Tygon tubing was
connected to the opened end of the stainless steel tubing on the
carbide electrode. A pinch valve was used to completely seal the
carbide cell from the environment.
[0315] The connected cells, which were successfully sealed and
isolated from the environment, were removed from the controlled
atmosphere glove box. The connected cells were set in place with
the bottom of each cell resting on a separate magnetic stirring
plate. The Tygon tubing connected to the top of the stainless steel
tube of the carbide electrode was connected to the valve which was
further connected to the vapor bubbler filled with methanol. The
pinch valve on the Tygon tubing was then opened to the carbide
cell. One side of a multimeter was connected to the zinc electrode
and the other side was connected to the carbide electrode allowing
for the flow of electrons across the cells. The multimeter also
permitted the voltage and current between the two cell to be
measured.
[0316] The reaction took place at room temperature. The vent valve
was opened between the carbide electrode and the vapor bubbler to
allow any vapor produced to exit the carbide cell. Next, both
magnetic stir plates were turned on to agitate the solution in each
of the cells. Finally, the valve on the glass tube connecting the
cells was opened to allow for ions to flow between the two cells.
The voltage and current were measured using the multimeter to
ensure that the reaction is indeed proceeding.
[0317] After a period of time, which was about 28 hours, the
reaction was stopped by closing the valve on the tube connecting
the two cells. The multimeter was disconnected along with the Tygon
tubing attached to the carbide electrode. The carbide cell cap was
removed along with the mesh stainless steel sphere containing the
products of the experiment. The products of the experiment were
then removed from the mesh stainless steel sphere and treated with
6.0 molar hydrochloric acid (HCl) and then flushed several times
with distilled water. The products of the experiment were confirmed
to be only elemental carbon using standard analytical methods.
[0318] The reaction products were determined to be clearly
different from the reaction products of Example 1 and were mainly
sp.sup.3 hybridized allotropes.
[0319] The elemental carbon material reaction products are depicted
in FIGS. 12-16. The elemental carbon produced from the tin
electrolysis experiments included mainly of three-dimensional solid
carbon particles which suggested that the carbon produced was
sp.sup.3 hybridized. FIG. 12 is a larger scale image of the bulk
carbon material produced by this experiment (scale bar, 100
microns). FIG. 13 is a magnified image of the material shown in
FIG. 10 that allows the three-dimensional nature of the carbon to
be identified (20 micron scale bar). FIG. 14 is an image that shows
the 3D crystalline nature of the carbon produced (10 micron scale
bar). FIGS. 15 and 16 are of the same particle at two different
scales (10 microns and 3 microns).
[0320] FIGS. 12-16 demonstrate that the products achieved were 3D
structures, as opposed to the 2D stacked plates obtained in Example
1. The sample from which these figures were taken is called Sample
B. Again, many interesting particles of interest were present in
the SEM images.
[0321] In Example 2, a voltage of about 10 mV was generated along
with an amperage of about 0.6 .mu.A on average. Again, other than
fluctuations there was no real change in the voltage or
current.
[0322] Examples 1 and 2 employed galvanic cells that used the
potential range of the reactions to determine which products could
be produced in that potential range. The galvanic cells did not
have a voltage source, but merely measured the voltage that exists
in galvanic cell during the reaction. The results demonstrate a
voltage range that produces specific products, with each specific
product being made at a specific voltage that occurred during the
reaction. Understanding the specific voltage associated with each
specific product can allow for the use of a electrolytic cell, with
the voltage controlled to the specific voltage, to produce a pure
specific product.
[0323] To prove this, Examples 1 and 2 differed only with respect
to the elemental metal electrode and cationic solution used, as
well as the reaction products produced. As elemental zinc in a
ZnCl.sub.2 solution has a different chemical potential than
elemental tin in a SnCl.sub.2 solution, the galvanic cells used in
Examples 1 and 2 have very different cell potentials. As such, the
total voltage in the cell is different in Examples 1 and 2,
creating different products. Products produced in Example 1 were
more sp.sup.2 hybridized, due to the specific range of cell
potentials produced by that reaction scheme. Products produced in
Example 2 were more sp.sup.1 hybridized, due to the specific range
of cell potentials produced by that reaction scheme. Accordingly,
Examples 1 and 2 demonstrate that changing voltage, and, therefore,
potential in the electrolysis cell can specify the carbon allotrope
products produced.
[0324] In each of the above Examples, the apparatus used did not
include an external voltage source. Accordingly, the voltage
between the cells decreased over time. This voltage change likely
resulted in variation in the produced material that, in theory,
would not be experienced if the voltage was maintained at a
constant level.
Example 3--CaC.sub.2+ZnCl.sub.2.fwdarw.CaCl.sub.2+Zn+C
[0325] In this experiment, a significantly larger apparatus was
used compared to that of Examples 1 and 2. The apparatus and items
used to conduct the processes for Examples 3 and 4 are shown in
FIGS. 19-23.
[0326] One day prior to the beginning of the experiment, methanol
was dried and prepared for the reaction using molecular sieves to
dehydrate the solvent. The zinc electrode was then prepared by
attaching the basket to the zinc rod and filling it with "mossy
zinc" (small nuggets of zinc with higher surface area made by
rapidly cooling molten zinc in water). The zinc electrode and
basket were then installed in the zinc cell by attaching it to the
underside of the zinc cell lid. The containers of zinc chloride
were weighed and numbered to determine the weight of zinc chloride
used in the experiment.
[0327] The calcium carbide was prepared by weighing out four equal
portions of 250 grams each (1,000 g total) and placing them in
sealed plastic tubs until the calcium carbide was loaded into the
carbide electrode. The vapor trap bubblers were filled with dried
methanol to prevent any of the oxygen or moisture in the air from
entering the cells of the reactor.
[0328] A basic cotton filter was inserted into the tube of the salt
bridge to prevent solids from transferring across the salt bridge.
The cotton filter was used rather than the frit for convenience in
scale up.
[0329] The carbide and zinc cells were isolated by closing the
valves to the salt bridge. All of the other valves were adjusted to
load the solvent into the cells. The multimeter was connect to the
carbide electrode and the zinc electrode. The multimeter was then
connected to a computer where the current and voltage can be
recorded.
[0330] The container containing the dried methanol solvent was
connected to the solvent loading port for the carbide cell using a
flexible PVC line designed to easily attach to the system and the
carboy. The air to the carbide circulation pump was turned on and
the methanol was poured into the system and pumped to the input at
the top of the carbide cell. Once the desired level was reached,
the pump was stopped and the container disconnected. The valves
were adjusted and the pump was turned back on to begin circulating
the solvent. The argon sparge was turned on to maintain the inert
atmosphere in the carbide cell.
[0331] Another container of the dried methanol solvent was then
connected to the solvent loading port for the zinc cell. The
compressed air was turned on to the zinc circulation cell and the
methanol pumped into the cell through the top circulation port.
Once the desired level of methanol was reached, the pump was
stopped and the solvent loading container disconnected from the
solvent loading port. The valves were adjusted and the circulation
pump was turned back on to circulate the methanol through the zinc
cell. The argon sparge was turned on to maintain the inert
atmosphere in the zinc cell. The pressure of the argon feed was
adjusted to the proper level at the regulator on the argon gas
cylinder.
[0332] The solid calcium chloride was then added into the methanol
of the carbide reactor. 150 grams of calcium chloride was added to
the solvent of the carbide cell. The concentrated solution of
CaCl.sub.2 in methanol was then added to the carbide cell.
[0333] The carbide circulation pump and argon sparge flow rates
were both increased to create additional agitation in the carbide
cell and aid in dissolving the calcium chloride into the
methanol.
[0334] The zinc chloride was then added to the methanol in the zinc
cell. Roughly 3.5 kilograms total of ZnCl.sub.2 was loaded in the
zinc cell for the reaction. The ZnCl.sub.2 was poured directly into
the top of the zinc cell. The zinc cell circulation pump and argon
sparge flowrates were both increased to increase the amount of
agitation in the zinc cell and aid in dissolving the zinc chloride
into the methanol.
[0335] Next the salt bridge was filled with solution from each side
and the solids filter saturated which permitted ion flow. The
carbide cell isolation valve was then opened and the solution was
allowed to fill the salt bridge to the solids filter. The vent
valve was periodically opened to bleed off any of the air or argon
trapped in the line. After several minutes when the solid filter
appeared saturated, the carbide cell isolation valve was closed.
The zinc cell isolation valve was opened to fill salt bridge with
solution on the zinc side of the solids filter. Once again, the
valve was left open for several minutes and the vent valve was
periodically opened to bleed off any gases.
[0336] The calcium carbide was loaded into the carbide electrode.
The flexible coupling that attaches the carbide cell lid to the
rest of the cell was loosened. The cell lid, flexible coupling, and
carbide electrode were lifted from the cell up to a point where the
bottom tray attached to the electrode could be loaded. Four trays
of 250 g of calcium carbide (1,000 g total) were loaded into the
respective locations.
[0337] The cell lid, flexible coupling, and carbide electrode were
lowered back into place and the coupling resealed to the top of the
carbide cell. The argon gas and circulation pump flowrates were
adjusted to the desired rates to begin the electrolysis reaction as
described more below. The desired rates produced a nice, consistent
agitation of the solution.
[0338] The multimeter was turned on and the voltage and current
verified to be at zero. The chemical reaction was begun by opening
the isolation valves for the carbide and zinc cells to permit the
flow of ions across the salt bridge. As the pure carbon production
reaction and the undesired secondary reaction between the calcium
carbide and methanol progressed, a portion of the reaction products
exited the trays of the carbide electrode in solid form. These
solids eventually settled into the products of reaction trap at the
bottom of the carbide cell. As the products of the reaction trap
filled with solids, they were drained and the carbide cell was
refilled to the same level with the volume of dried methanol that
was removed.
[0339] The vent valve on the lid of the carbide was cracked open.
The solids, along with a small portion of the methanol solution,
were drained by opening the valve at the bottom on the carbide
cell. The mixture was drained directly from the carbide cell into
individual polypropylene tubs designed to be used in a large bucket
centrifuge. Once the solids were removed and the drain valve
closed, the vent valve on the lid of the carbide cell was closed.
Then the container of dried methanol was connected to the solvent
loading port. An equal amount of dried methanol as was removed was
added using the carbide circulation pump. The container of dried
methanol was removed and all valves were properly adjusted to once
again circulate the solution.
[0340] The reaction was complete when the current reading from the
multimeter dropped to zero. This indicated that the electron flow
had ceased because all of carbide had been consumed or there was
not enough contact between the remaining pieces of carbide and the
electrode to sustain a current flow. Once the reaction stopped, the
solution and any accumulated solids were drained out of the carbide
cell into the individual centrifuge tubs at 750 ml per tub. Each
tub was centrifuged with the liquid solution decanted and collected
for further solvent recovery operations and the solids containing
the pure carbon product remained in the centrifuge tub to begin the
cleaning and separation process. The decanted liquid was stored in
one gallon containers which will be further processed in the
distillation column. During this time, the carbide cell circulation
pump continued to run and wash any solids from the cell walls,
electrode, and the surface of the unreacted carbide to be removed
with the liquid solution.
[0341] After the carbide cell was drained, the flexible coupling at
the top of the cell was loosened. The lid was raised from the cell
and the bottom portion of the electrode containing the carbide was
removed. Any unreacted carbide was collected and weighed for mass
balance calculations. An acid solution was then applied to clean
out the inside of the reactor. Then a small amount of the solvent
for the next experiment was circulated through the cell to rinse
any of the acid solution away and absorb any water molecules
present from the mild acid solution.
[0342] The drained material was placed into a centrifuge tub. The
centrifuge tub was then centrifuged in the large bucket centrifuge
at a speed of 3500 RPM for ten minutes. The solids formed a cake at
the bottom of the centrifuge tub and the liquids were decanted off
to be further processed in the distillation column. The remaining
solids were treated with a 3.0 molar HCl solution. The HCl was
allowed to react with the reaction products on a stir plate
providing agitation overnight. The solution was then
centrifuged.
[0343] The solids were then further treated with a stronger HCl
solution of 6.0 M. The acid treatment was allowed to proceed for 24
hours. The acid treatment was repeated three times. The remaining
solids were transferred from the centrifuge tub into a fine
particle size glass fritted using distilled water and mild acid
solutions. The glass fitted filter was placed on top of a vacuum
flask with a gasket and attached to the house vacuum system to pull
the water and methanol flushes through the material and filter. The
residual salts were rinsed away by continual flushing of the
product with distilled water and methanol. The final flush was
performed with methanol so that the product was completely dried
before it was removed from the filter and weighed for mass
balance.
[0344] The reaction solvent was recovered by distilling the
solution drained from each of the cells. After centrifugation, the
methanol/calcium carbide solution was collected. A portion was
loaded into the boiling pot of a distillation column. The solution
was heated to a point that the solvent was evaporated from the
solution and further condensed and recovered in the collection
flask. The remaining concentrated calcium chloride solution was
dried to solid calcium chloride and discarded. Calcium chloride was
generated by the process.
[0345] Once all of the methanol/calcium chloride solution was
distilled, the methanol/zinc chloride solution was then distilled.
The solvent was evaporated from the solution and recovered in the
collection flask.
[0346] 14.6 grams of pure carbon product was recovered (3.9% yield
of carbon). Some the carbon was unreacted and removed as acetylene
in the cleaning process. Other carbon was reacted with the methanol
in the undesired secondary reaction.
[0347] The time of the reaction was about 15 days.
[0348] The elemental carbon product from Example 3 was examined by
SEM and EDAX and Raman spectroscopy. Stacked plate-like structures
were observed. In some cases, the diameter or lateral dimension of
the stacks were decreasing continuously so that an exfoliation
process should provide graphene plates of different diameters or
lateral dimensions. See FIGS. 24-27.
Example 4--CaC.sub.2+ZnCl.sub.2.fwdarw.CaCl.sub.2+Zn+C
[0349] In Example 4, the procedures of Example 3 were generally
repeated. However, several changes from the procedures of Example 3
were made prior to the start of the experiment.
[0350] The first was that the methanol in the vapor trap bubblers
was replaced with vacuum pump oil to prevent evaporation and
maintain the barrier between the inert atmosphere of the reactor
and the atmospheric conditions inside the laboratory. The second
change to the apparatus was to remove the solids filter in the salt
bridge and replace it with more substantial solids filters. Instead
of the loose cotton filter, two discs were cut from a sponge to fit
snugly inside of the connection tube. The loose cotton was then
compressed between the two discs which completely prevented the
migration of the solids from the carbide cell to the zinc cell.
Once the reaction began, there was no observable decrease in the
current from the initial experiment.
[0351] The methanol was replaced with vacuum pump oil in the vapor
trap bubblers because the methanol can evaporate overnight and the
barrier between the inside of the reactor and the atmosphere can be
broken. As described below, the more substantial solid particle
filter was added to the salt bridge to better prevent solid
material from migrating from one cell to the other.
[0352] Additionally, the solid calcium chloride was dissolved in
dried methanol before introducing it into the carbide cell.
[0353] After the reaction was stopped and the carbide cell drained,
the carbide remaining in the electrode was removed and processed to
determine if there was any pure carbon product retained in the
carbide. The remaining carbon products on the carbide were
removed.
[0354] The carbide cell circulation piping was also connected to
the vapor vent valve on the salt bridge. When the solids were
flushed from the salt bridge there was no change to the current or
voltage of the system further indicating that the temporary change
of flow did not affect the reaction. The electrolysis reaction was
stopped after 17 days.
[0355] 19.1 grams of pure carbon were recovered (5.1% yield for
carbon).
[0356] The elemental carbon product from Example 4 was examined by
SEM and EDAX and Raman spectroscopy. Stacked plate-like structures
were observed. Hexagonal structures and flat surface structures
were observed. See FIGS. 28-31.
[0357] FIG. 32 is also an SEM image (scale bar, 50 microns)
produced from Example 4. It is a composite particle of elemental
carbon or graphene-like plates. It appears to be a fused together
particle of smaller individual hexagon shaped stacks of
graphene-like plates.
Example 5--CaC.sub.2+ZnCl.sub.2.fwdarw.CaCl.sub.2+Zn+C
[0358] This example was carried out using the same apparatus as
used in Examples 3 and 4 with the exception being the solvent used
in the reaction. The methanol used as the solvent was replaced with
ethanol. Ethanol reacts with the CaC.sub.2 at a much reduced rate
relative to reaction of methanol with CaC.sub.2. However, the
solution of the salts in ethanol is less conductive than in
methanol and, therefore, the rate of the desired elemental carbon
producing reaction was also reduced. Because of the decreased
reaction rate, the reaction time of Example 5 was allowed to
proceed for 27 days which produced some large particle size pieces
of elemental carbon material.
[0359] After the reaction portion of Example 5 was complete, it was
discovered that an undesired zinc hydrate material was dissolved in
the solvent of the carbide cell. When water was added, the
undesired material precipitated out of solution and produced a
gel-like material. This undesired material complicated the cleaning
process. In addition, a more rigorous cleaning produced was used to
ensure that most, if not all, of the contaminants were removed.
Furthermore, the material produced was classified into a fine,
middle, and large cut based on a need to produce smaller particle
size product for a characterization analysis.
Summary of the Cleaning Process for Example 5:
[0360] After the reaction was complete, the valve on the salt
bridge was closed isolating the two cells. Roughly 3 liters of the
solution from the carbide cell were drained into six separate
centrifuge tubs for the large bucket centrifuge. The solution was
centrifuged no solid material was forced out of solution. Water was
then added to the first time and a material precipitated
immediately. This was later identified as a zinc hydrate compound.
This undesired zinc hydrate precipitated immediately upon contact
with water and was very difficult remove and separate from the
other products of reaction. The goal would be to isolate the
product from the solution before it has a chance to precipitate.
This was done by first decanting off the solution from the products
of reaction. Dried ethanol was immediately used to immerse the
products so any residual solution would not react with the moisture
in the air and form the undesired zinc hydrate material. This
action was repeated several times with dried ethanol in order to
dilute and flushed away any of the residual solution and eliminate
the formation of the undesired zinc hydrate.
[0361] The zinc hydrate did form to a small extent due to short
exposure times to the air. The only thing it had responded to is
concentrated or 13.0 M hydrochloric acid. The effort was made to
use only the standard cleaning and separation chemicals to deal
with this undesired material. The next step was to dissolve away
any of the unreacted calcium carbide. Based on the material
remaining, there was a large amount of the calcium carbide left
unreacted. Acid solutions were mixed with the unreacted products of
reaction to react away the calcium carbide. This treatment also
remove any residual salts. The remaining product is a high
percentage of elemental carbon greater than 90%.
[0362] Additional operations were performed in order to further
remove any residual materials or contaminants an increase the
percentage of elemental carbon and the product. Operations were
also performed to separate the product into three distinct particle
size cuts. The remaining products are separated into several
different beakers. Several more rinses were performed with HCl. The
supernatant liquid was decanted through a 4.5-5.0 .mu.m glass
fritted filter. After several additional acid treatments, the
products of reaction were then split into only a few beakers and
the products immersed in dried ethanol. These beakers were placed
in the ultrasonic bath and left for several hours. The beakers were
removed from the ultrasonic bath and placed on stir plates for
roughly 10 minutes. The beakers were removed from the stir plate
and allowed to sit for a length of time and allow the product to
settle out of solution based on and particle size. The supernatant
liquid was then decanted through the glass fitted filters. The
solids retained by the filters were then separated and collected
representing the fine particle size cut of the product. This action
continued numerous until the product was sufficiently cleaned and
separated into three distinct particle sizes.
[0363] The procedures below describe in more detail various
cleaning and classifying procedures for this experiment.
Rigorous Cleaning and Classifying Procedure:
[0364] The process of cleaning the carbon produced in Example 5 was
complicated by the formation of a zinc hydrate material as an
undesired product. This phase of the experiment in Example 5
started with all of product distributed between five one liter
beakers and one larger three gallon bucket with lid.
[0365] The three gallon bucket contained all of the solvent drained
from the electrolysis reactor where the solvent also contained the
small particle size (fine) carbon material. The bucket was left
undisturbed for several days allowing the fine carbon to settle out
of solution. Normally, the fine carbon would be separated out of
the solvent using a large centrifuge. But for this experiment, the
enhanced gravity of the centrifuge was unable to force the solids
from the solution. From past experiments, it was learned that that
fine material that could not be recovered via centrifugation would
eventually settle out of solution if left undisturbed.
[0366] The five one liter beakers contained all of the solid
product that remained in the solid contained in the baskets of the
carbide electrode. They also contained all of the other non-carbon
material from the electrolysis reaction after the unreacted carbide
was treated with one concentrated HCl treatment. The solutions in
the beakers also contain any of the undesired zinc hydrate material
remaining from the reaction. The first objective was to separate
and recover the maximum amount of product in most time efficient
method possible so the product could be treated with HCl for a
second time with all (or the vast majority) of the undesired zinc
hydrate material finally removed.
[0367] The apparatus used for separating the solid product from the
solution was a fine particle size (4.0-5.5 micron) glass fritted
filter placed on top of a two liter vacuum flask. A gasket was
place under the filter using vacuum grease to seal it to the vacuum
flask. The flask was connected to the house vacuum system to pull a
vacuum inside of the flask which, in turn, pulls the liquid and
ions in solution through the filter leaving a solid that had a much
greater concentration of pure carbon product.
1. Set-Up of the Equipment to Perform the Cleaning/Separation:
[0368] Prior to setting the filter/vacuum flask apparatus, the
glass fritted filters were all thoroughly cleaned to provide an
opened filter for the greatest flow rate of the solution through
the filter. This was accomplished by cleaning the filter with the
laboratory glass cleaner and then placing the filters in the
furnace overnight at 500.degree. C. in an oxidizing environment
which reacts any material entrained in the filter to produce ash.
The underside of the filter was then subject to vacuum and flushed
with methanol to rinse any of the now smaller particle size ash out
of the glass fitting.
[0369] Cleaning the glass fritted filters using this
cleaning/oxidation/rinsing method were performed on a regular basis
at the end of each day while previously cleaned filters were
rotated in. This increased the efficiency of the filtering process
by maintaining as high of flow rate through the filters as possible
given the situation.
[0370] Four of the filter/vacuum flask system were set up and
filtering process to begin the filtering process from the first HCl
treatment. The undesired zinc hydrate material forms a gel like
substance. The gel settles on the surface on the glass fitted
filter which partially or completely blinds the filter. A blinded
filter means that something (the zinc hydrate gel) is preventing or
greatly restricting the solution from being pulled through the
filter. This is why it was so important to finally remove all of
the zinc hydrate and allow the product to be properly cleaned. The
solid product is also pulled to the surface of the filter which
also acts to blind the filter.
[0371] Two of the four filter systems were started, and as expected
the flow rate through the filters was very low, only a drop or two
every few seconds. One way to increase the rate of transfer through
the filter was to continually move the blinding material from the
glass fritted surface using glass stirring rod or rubber laboratory
spatula. An additional option is to add concentrated HCl (the other
chemical use on a regular basis in the process which dissolved the
zinc hydrate gel) directly to the filter. But this method is only
effective for the filter blinding due to the gel and does not help
with blinding from the fine product material in the filter.
[0372] One goal was to isolate smaller particle graphene materials
(under 20 microns) for further testing in products. Therefore,
another object of the cleaning and separation procedure is to
separate the product by particle size and supply the finer cut of
the carbon for product testing of Example 5 product. So in addition
to cleaning and purifying the product, the next few steps will
begin the process of separation by particle size.
[0373] In addition to separating out the finer carbon for further
product testing, the particle size separation is important for
Example 5 because it appears that there are several pieces of very
large product. Another object was to separate out the very large
pieces (on the scale of one to two centimeters) for further
evaluation and analysis to control better the growth mechanism of
the pure carbon product using the electrolysis reaction.
[0374] Two additional one liter beakers were used to decant off the
supernatant liquid containing a smaller amount of the fine carbon
product. Smaller amount means the percentage of solids per volume
of supernatant liquid.
[0375] Any of the solids leaving the beaker with the decant
solution will include the smaller particle size carbon material.
Since the product is mostly pure carbon at this point the specific
gravity for the solids should be fairly consistent. This means that
the settling rate of the material is controlled by the particle
size. The smaller the particle, the smaller percentage of the
forces acting on it will be gravity. Therefore, as settling time
increases, smaller and smaller particle size solids will remain
suspended in the solution.
2. Processing the Gel-Like Clumps of Material:
[0376] Several of the beakers contained a large `clump` of the gel
suspended in the supernatant liquid which also had product
entrained. These clumps were decanted one at time into the first of
the one liter decant beakers. Once the clump was isolated in the
beaker it was treated with additional concentrated HCl and agitated
for as long as need to dissolve the undesired zinc hydrate
clump.
[0377] Once dissolved, the contents of the first decant beaker were
added to the filter and the solution allowed to be separated away.
The filters only hold a maximum of 150 ml so the contents of the
beaker were continually added during filtration until the entire
contents of the beaker were filtered.
[0378] Any of the residual material remaining in the beaker was
transferred to the filter using methanol. Furthermore, the solids
were flushed several times (between 2-4 times) with methanol to
remove impurities from the surface of the material prior to the
second acid wash. It was important to use methanol instead of
distilled water because water can react to form additional small
amounts of the gel substance.
[0379] After the material was dried from the vacuum, it was
transferred into the fine carbon collection beaker using the
spatula and methanol. This fine carbon beaker also contained
concentrated HCl for the second acid wash. The filter was put aside
to be cleaned and oxidized while a fresh, cleaned filter was sealed
to the vacuum flask to process the next dissolved `clump` of
gel-like material containing solids.
[0380] The steps in this section were repeated until all of the
`clumps` of the gel like material have been processed and the
product recovered for the second acid treatment.
3. Processing the Supernatant Decant Solution and the Products it
Contains:
[0381] In addition to processing the gel-like material, the rest of
the supernatant liquid containing the finer particle size carbon
product was being processed simultaneously. This section of the
cleaning/separation process requires the largest volume of the
supernatant liquid to be processed which is the most time intensive
part of the filtration due to the partial blinding of the glass
fritted filters. So the main object for this step was to recover
the maximum amount of solid product while removing most if not all
of the undesired zinc hydrate in the most time efficient
method.
[0382] The second decant one liter beaker was used and a third
decant beaker was added. This step began by decanting the
supernatant while fine solids from the five original beakers. All
of the beakers that did not contain any of the gel like clumps were
decanted into the second decant beaker and allowed to sit overnight
for the solids to settle.
[0383] After the `clumps` where removed from the other beakers,
they were then decanted into the third decant beaker the following
day and allowed to settle overnight. The large clumps were not in
this step, but the undesired zinc hydrate was still present in the
solution so the filter blinding from the gel was still a problem.
But main factor in the flow rate through the filter was now the
blinding due to the fine particle size solids. This is why the
decant beakers were allowed to settle overnight. Much of the
supernatant solution could be processed through the filters with
only minimal amount of the solid product available to blind the
filter.
[0384] After the solids had settled, the solution was continually
added to the filters. This step processed at a reasonable rate as
long as the majority of the solids were retained in the decant
beakers but still took several days to complete. The blinding was
managed in the same manner as the previous step where the filter
surface was exposed using a glass stirring rod and rubber spatula.
Concentrated HCl was also added directly to filter to dissolve any
the gel like material forming on the surface of the filter.
[0385] Due to the volume of solution, there were several instances
where the filter became totally blinded, meaning that the flow rate
through the filter dropped to zero. In this case, the contents of
the filters were transferred back into the decant beaker using
methanol and allowed to settle. A clean filter replaced the blinded
filter and the process continued. The blinded filter was cleaned
and oxidized to be used later.
[0386] This step proceeded by processing one of the decant beakers
while the other was used to collect material as to allow the solids
to settle. The next day, the settled beaker was processed.
[0387] Once the volume of the filter was filled with anywhere
between 10%-40% with solids (depending of the flow rate of solution
through the filter), the solids were flushed several times with
methanol to remove any residual material from the surface of the
material. The solids where then transferred in the fine carbon
beaker along with the material from the `clumping` process step to
wait the second acid treatment.
[0388] The steps in this section were repeated until all of the
decanted material was processed.
4. The Second HCl Acid Treatment and Alcohol Rinses of the Fine
Carbon Product:
[0389] Once all of the decanted products where processed into the
fine carbon beaker, it was filled with concentrated HCl, agitated
on a magnetic stirring plate, and allowed to react for 40
hours.
[0390] After the HCl treatment, the solids were allowed to settle
overnight to minimize the time required to filter the large volume
of liquid.
[0391] The entire contents of the fine carbon beaker were filtered
using the same methods as the previous steps using multiple
filter/vacuum flask systems.
[0392] Once the solid material was mostly dried from the solution
in the beaker, it was flushed and agitated in the filter with
roughly 100 ml of methanol anywhere between 8-12 times. This
removed most if not all of the impurities from the surface of the
pure carbon products.
[0393] After the fine carbon product solids had dried in the filter
under vacuum, it was transferred into a 600 ml Berzelius tall form
beaker for additional cleaning and refining steps. At this point,
the fine cut should only contain the pure carbon product with trace
amounts of impurities, most of which may be trapped in between the
stacked sheets of graphene.
5. Processing the First HCl Acid Treatment of the Coarse Carbon
Product:
[0394] The coarse, or larger particle size cut, of the pure carbon
product is still contained in the five original one liter beakers
immersed in a volume of the solution just great enough to cover the
solid material. At this point, most of the mass of product is
contained in this coarse cut in the five separate beakers. Although
much of the material needs to still be filtered from the first HCl
treatment, the time required should be about the same since there
is much less supernatant liquids that must pass through the glass
fritted filter. In addition, the particle size of the solids is
greater, so the blinding due to the solid material should be less
of problem than with the finer cut of the solid product.
[0395] The solids, along with the supernatant liquid, were
transferred into a filter. Methanol was used if needed to transfer
any of the material from the beaker into the filter. The volume of
the filter is filled between 30%-40% with solids and the
supernatant allowed to separate through the filter.
[0396] After the material in the filter had partially dried, it was
flushed and agitated with roughly 100 ml of methanol and allowed to
filter. The methanol flush was repeat between 3-4 times. At this
point the solid should contain a concentration of pure carbon
material.
[0397] The solids where transferred from the filter into a clean
one liter beaker to await the second HCl treatment.
[0398] All of the remaining solids in the five original beakers
were processed using this method. The volume of material was large
enough that two one liter beakers were needed for the second HCl
treatment of the coarse cut of the carbon product.
6. The Second HCl Acid Treatment and Alcohol Rinses of the Coarse
Carbon Product:
[0399] The two beakers containing the coarse cut of solids from
Example 5 were filled with concentrated HCl, agitated on a magnetic
stirring plate, and allowed to react for roughly 40 hours.
[0400] After the HCl treatment, the solids were allowed to settle
overnight to minimize the time required to filter the large volume
of liquid.
[0401] The entire contents of the coarse solids beakers were
filtered using the same methods as the previous steps using
multiple filter/vacuum flask systems.
[0402] Once the solid material was mostly dried from the solution
in the beaker, it was flushed and agitated in the filter with
roughly 100 ml of methanol anywhere between 8-12 times. This
removed most if not all of the impurities from the surface of the
pure carbon products.
[0403] After the fine carbon product solids had dried in the filter
under vacuum, it was transferred into a single one liter Berzelius
tall form beaker for addition cleaning and refining steps. At this
point, the coarse cut should only contain the pure carbon product
with trace amounts of impurities, most of which is probably trapped
in between the stacked sheets of graphene.
7. Sonication Treatment and Settling Rate Separation of the Pure
Carbon Product from Example 5:
[0404] Sonication is the method of applying sound energy to a
system, in this case applying sound energy to a beaker filled with
a solution containing solid particles including stacks of two
dimensional sheets. Sonication is a widely used method of agitating
and dispersing solutions containing solid particles. It is also a
technique used to disperse commercially purchased graphene, which
arrives as large pieces of agglomerated graphene sheets. This
agglomeration is normal as the graphene sheets dry.
[0405] For the Example 5 cleaning and separation process, the
solids in the fine particle and coarse particle beakers were
immersed in methanol and the beakers suspended in a Cole-Parmer
8854 Ultrasonic bath. In addition to dispersing the solids, it is
believed that the ultrasonic energy with solids immersed in the low
surface tension methanol will allow the liquid to penetrate the
areas between the graphene sheets to a greater extent. The
penetration of the methanol between the graphene sheets will
dissolved and remove more of the calcium ions and other impurities
remaining in the final carbon product.
[0406] Another possible advantage of the sonication treatment of
the product is the exfoliation of the graphene sheets. There has
also been research into graphene exfoliation using various
solvents. So it was expected that exfoliation during the sonication
treatment will occur but it was unclear to what extent exfoliation
will occur. If the graphene sheets are exfoliated, then removing
any impurities from between the sheets while they are stacked will
become much more effective and efficient. Furthermore, exfoliated
graphene can be laid down as a film, and the quality of the
material produced can be more accurately assessed.
[0407] In addition to the sonication treatment, the solid material
was also separated by particle size during this section of the
process. When the beakers were removed from the ultrasonic bath,
they would be agitated using a magnetic stirring bar. The agitation
would be stopped and the supernatant liquid with suspended solids
would be decanted into a beaker or directly into the glass fritted
filter. There was usually a brief amount of time (no more than a
few minutes) to allow for the larger particles to settle out of the
supernatant solution. During the few moments of settling, any
larger particles that were suspended in the solution during
agitation settled to the bottom of beaker before the smaller
particles which stayed suspended for a long period of time.
Therefore, the solid particles suspended in the supernatant
solution would be the smallest particle size material on average.
This is how the particle size separation for the carbon material
produced was accomplished.
[0408] The following is the procedure used for sonication treatment
and particle size separation of the solid material from Example
5:
[0409] Both the fine particle size and coarse particle size beakers
were suspended in the ultrasonic bath. By suspended in the bath,
they were held in place using an adjust laboratory clamp. The
beakers were filled roughly half way with methanol.
[0410] During the first day, the ultrasonic bath was allowed to run
for one hour. The beakers were periodically agitated during this
hour to rearrange which solid particles were closest the glass
surface of the beaker or closest to the source of the sonic
energy.
[0411] The beakers were removed from the ultrasonic bath, dried
off, and placed on magnetic stirring plates. The solid particles
were agitated for 10-15 minutes. The beakers were then removed from
stirring plates and placed back into the ultrasonic bath for
another hour. This process was repeated several times for an entire
day.
[0412] At the end of the day, the beakers were placed in the hood
and the solid particles allowed to settle overnight.
[0413] The next morning, the supernatant liquid which contained
almost no solids was decanted into two separate filters, one for
the fine particle size carbon and one for the coarse particle size
carbon.
[0414] The beakers were filled about half way with methanol and
place in the ultrasonic bath for further sonication treatment.
[0415] At this point, the treatment of the two beakers diverges.
Both beakers of material will still continue to receive sonication
treatments, but the smaller particles suspended in the supernatant
liquid of the coarse solid beaker will be decanted prior to
allowing the particles to settle out of solution. The decanted
solid particles of carbon product from the coarse beaker will then
be filtered and flushed with methanol before being added to the
fine particle beaker for continued processing. This process allows
the smallest carbon particles (on average) from the coarse portion
of the product to be removed and added to the fine portion of the
product. The separation will not be perfect, but the majority of
the finest carbon product will be contained in the fine particle
beaker.
[0416] After one hour in the ultrasonic bath, the coarse beaker was
removed and placed on the stirring for several minutes. The coarse
beaker was then removed and allowed to settle for several
additional minutes.
[0417] The solids and supernatant liquid were then decanted into
the filter. The liquid was to transfer through the filter leaving
behind the solids.
[0418] Once the solids in the filter were partially dried from the
vacuum, they were flushed 3-4 times with methanol to remove any
residual contaminates from the surface.
[0419] After the fine cut of solids from the coarse beaker were
flushed, they were transferred into the fine particles beakers.
[0420] The decanted coarse beaker was then partially filled with
methanol and placed back in the ultrasonic bath. The sonication
energy continued to disperse the solids allowing the smaller
particles to become suspended in the solution. These particles can
continue to be separated out until the smallest particle size
material is transferred from the coarse particle beaker into the
fine particle beaker.
[0421] This process is continued until the agitated particles in
the coarse beaker settled out of solution very quickly (almost
immediately). This indicated that the smallest particle size solids
have been removed from the coarse cut of the product into the fine
cut of the product.
[0422] The objective behind this separation technique was to
generate a reasonable amount of pure carbon product mostly of the
finest particles size. This was to prepare a fine particle size
product for further product testing consisting of material subject
to an extensive cleaning process to remove contaminates.
[0423] Over the several days of the particle size separation, the
fine particle beaker continued to receive sonication treatment.
[0424] Every 2-3 hours the fine solids beaker was removed from the
ultrasonic and allowed to settle for roughly 15 minutes.
[0425] The supernatant liquid was decanted into a filter/vacuum
set-up. After the liquid was removed, any solids were flushed
several times with methanol and then added back to the fine
particle beaker for further sonication treatment.
[0426] When the particle size separation was complete, the entire
contents of the fine particle size beaker were transferred the
several filters. In each of the filters, the fine particle size
carbon product was flushed several time with methanol and allowed
to dry from the vacuum.
[0427] Once the solids in the filters were dry, they were placed
inside in the drying oven at 105.degree. C. to drive off any
remaining methanol or other moisture.
[0428] When the product was completely dried, the filters were
removed from the drying oven and allowed to cool.
[0429] The product was weighed and transferred to a Fine Particle
Size Carbon Product sample container.
[0430] Characterization of the large piece of product of the
elemental carbon material reaction product is further shown in
FIGS. 33-45.
[0431] FIG. 33 shows a comparison between the very large piece of
Example 5 and commercial graphene of much smaller size.
[0432] FIG. 34 is a first SEM image showing a top view of a large
piece of carbon product (Sample C) (scale bar, 200 microns). FIG.
34 shows a magnified image of a piece of large graphene produced in
Example 5. The image shows the edge of the solid piece that extends
beyond the range of the image. It also shows a fragment of a
hexagon shaped piece of elemental carbon. It is typical to find
elemental carbon hexagons with a cross-sectional area of roughly 50
.mu.m. This is roughly the cross-sectional area of the fragment
seen in the picture and is used along with the edge of the piece to
give a representation of the large scale of this carbon piece in an
SEM image.
[0433] FIG. 35 is a second SEM image showing Sample C with a
perspective view (scale bar, 200 microns).). FIG. 35 shows the edge
of the elemental carbon piece seen in FIG. 34. With the naked eye,
one could see that the large elemental carbon pieces produced in
Example 5 had a two dimensional shape. FIG. 35 shows the edge or
the depth of the two dimensional piece. It also shows that the
solid piece appears to be made up of individual sheets of elemental
carbon or graphene.
[0434] FIG. 36 shows Raman spectra for Sample C. These are Raman
spectra generated from different samples all overlaid on top of one
another. The G peak and the 2-D peak are roughly the same height.
This is unique because other Raman spectra observed for material
produced using this process produces a Raman spectra where the G
peak is a good deal higher than the 2-D peak. This indicates that
for this sample in Example 5 the sample is thinner on an atomic
level in the third dimension and that this material has different
characteristics from the other materials produced using this
galvanic cell technology.
[0435] FIG. 37 is an SEM image showing Sample C and material
morphology within crevices (scale bar, 40 microns). FIG. 37 is a
magnified image of FIG. 35. FIG. 35 appears to show several (two or
three) composite layer made up of smaller layers. In between the
larger layers of FIG. 37 there are graphene hexagons contained
within the gap. These hexagons have the very commonly seen
cross-sectional particle size of roughly 50 .mu.m.
[0436] FIG. 38 shows an optical micrograph for top view of Sample C
(scale bar, 390 microns). FIG. 38 shows an optical image of the
overall large carbon piece. From this image, it can be clearly seen
that this is not tiny graphene flakes (on the order of single
microns or tens of microns) coagulated together because it has
dried and was not in solution. It also shows the overall size of
the elemental carbon particle given the scale bar on the bottom
right of 390 microns.
[0437] FIG. 39 shows an optical micrograph for perspective view of
edge of Sample C (scale bar, 240 microns). FIG. 39 shows the same
graphene piece as in FIG. 38. However, in FIG. 39, the angle of the
optical image is rotated from perpendicular so the third dimension
can be observed. This image further shows the stacked two
dimensional nature of the large graphene particle.
[0438] FIG. 40 is an SEM image showing Sample C (scale bar, 30
microns). FIG. 40 shows an image of elemental carbon produced from
Example 5. FIG. 41 is a magnified image of the same piece of
carbon. The most interesting things about these two SEM images are
the tiny fin like projections from the surface. In FIG. 41, it is
also interesting to look at the orientation of the overall
particle. Some of them appear to be perpendicular to one another
while some of them appear to be at fairly consistent angles.
[0439] These images, and other images shown herein, show evidence
of specific elemental carbon materials and graphene materials that
can be produced using this technology.
[0440] In addition, in FIGS. 42-45, comparative examples are shown
for different scale bars between the elemental carbon materials
from the prior thermal methods (U.S. application Ser. No.
14/213,533 and PCT Application PCT/US2014/028755) compared to
Example 5.
Example 6
[0441] The same basic set up as Examples 1 and 2 with the small
glass reactor shown in FIG. 17 was used for this experiment.
However, there are three major differences between Examples 1 and 2
and this example. The first is that the anode and cathode in the
reaction were both connected to a potentiostat which applied an
external voltage to the reaction system. The applied external
voltage would in turn alter the chemical potential of the reaction.
The second major difference was in the apparatus itself. The glass
caps which held the two electrodes were replaced by large rubber
stoppers. This change was made because it was more effective in
sealing the reaction environment and also permitted for different
setups to be quickly changed and altered between experiments. For
example a glass caps in Examples 1 and 2 could not accommodate a
reference electrode. A simple alteration of the rubber stoppers
would allow for either cell to accommodate the reference electrode
or any other item needed to perform the experiment. The third major
difference was that ethanol was used as the solvent in this
experiment as opposed to methanol which was used in Examples 1 and
2.
[0442] A new anode was fabricated identical to the anode used in
Examples 1 and 2. They included a spherical tea ball strainer
supported by a rod where one face rotates to seal the strainer.
This strainer included a carbon steel with a stainless steel
coating. It was selected for initial experiments because it easily
met the requirements of the experiment. These requirements were to
hold the carbide and provide an electrically conductive surface and
had a greater resistance to corrosion than carbon steel. A quarter
inch 316 stainless steel rod was connected to the tea strainer with
a hole was drilled in the side to vent any pressure build up in the
carbide cell. The stainless steel rod passed through the rubber
stopper and supported the anode within the cell. The top of the
tube was connected to bubbler which provided a separation between
the reaction environment and the environment in the lab.
[0443] The first cell was filled with the dried ethanol to a height
of four inches or one inch above the connecting tube. Zinc chloride
anhydrous salt (ZnCl.sub.2) was stirred into the dried ethanol
until the solution was saturated. The cell cap, which was fitted
with a 1/4'' diameter elemental zinc rod was set in place using
vacuum grease on the ground glass joint to seal the zinc cell. The
bottom of the elemental zinc electrode was immersed in the
ZnCl.sub.2/ethanol solution.
[0444] The second cell was also filled with the dried ethanol to
height of four inches or one inch above the connecting tube.
Calcium chloride anhydrous salt (CaCl.sub.2)) was stirred into the
dried ethanol until the solution was saturated.
[0445] The calcium carbide (CaC.sub.2) was then prepared by
reducing the particle size of the individual pieces to a size of
roughly one centimeter. Calcium carbide was purchased from Acros
Organics and the product name was Calcium Carbide, 97+% (CAS:
75-20-7 and Code: 389790025). The calcium carbide was not treated
or purified before the start of the experiment.
[0446] The CaC.sub.2 was then sealed in the hollow stainless steel
mesh sphere of the carbide electrode which had been fitted into the
carbide cell cap. The carbide cell cap was set in place into the
ground glass joint to seal the carbide cell. The mesh sphere
containing the calcium carbide was completely immersed in the
CaCl.sub.2)/methanol solution. Tygon tubing was connected to the
opened end of the stainless steel tubing on the carbide electrode.
A pinch valve was used to completely seal the carbide cell from the
environment.
[0447] The cap for the cathode cell was prepared with two openings.
The first opening was in the center of the cell and held the
elemental zinc rod which was immersed in a solution of dried
ethanol and zinc chloride. The second opening was roughly half way
between the center of the cell and the wall. This opening held the
Ag/AgCl.sub.2 reference cell where the tip was also submerged in
the solution. The anode, cathode, and reference electrodes were
snugly fit in and sealed in the holes of the rubber stopper for the
cell caps.
[0448] Once both cells have been sealed and the electrodes in
place, the potentiostat and an amp-meter were connected in series
between the zinc and CaC.sub.7 electrodes. The potentiostat was a
bioanalytical systems Inc. (BAS) Power Module model PWR-3.
[0449] The vent valve was opened between the carbide electrode and
the vapor bubbler to allow any vapor produced to exit the carbide
cell. Next, both magnetic stir plates were turned on to agitate the
solution in each of the cells. Finally, the valve on the glass tube
connecting the cells was opened to allow for ions to flow between
the two cells. The voltage and current were measured using the
multimeter to ensure that the reaction was indeed proceeding.
[0450] The reaction that is expected to occur is:
CaC.sub.2+ZnCl.sub.2.fwdarw.2C+CaCl.sub.2+Zn
In this reaction, Zn.sup.+2 is reduced to elemental zinc. The
carbide anion is oxidized to elemental carbon. The standard
reduction potential of either half-cell is not known in ethanol. It
has been observed that this reaction occurs spontaneously at room
temperature.
[0451] With an applied potential of 0V, a current of 5 uA was
measured. A voltage of 14V was applied. The current increased from
5 uA to 100 uA. This is significant, as it implies an increase in
reaction rate. The zinc cell became clear as the reaction
progressed, implying that the zinc chloride was consumed. More zinc
was added, until there was undissolved zinc chloride in the cell.
The current increased to 150 uA. As the reaction continued, the
current steadily increased to 200 uA. This is probably from the
formation of calcium chloride in the calcium cell. The production
of calcium chloride would increase the conductivity of the
electrolyte. The reaction was allowed to continue for 4 days. After
the fourth day, both cells were an opaque white, and the current
had increased to 280 uA. The reaction was stopped. Both cells were
emptied, and the products were cleaned with acid.
[0452] The reaction appeared to have occurred as predicted. It is
unclear if any zinc metal was deposited onto the zinc rod. The
calcium cell is likely white from calcium oxide and excess calcium
chloride. Several large pieces of carbon were formed in the
reaction. Some of the pieces appear to be very flat, similar to the
graphene produced from earlier reactions. The stainless steel
electrode appeared to be unchanged from the reaction. Previous
reactions caused significant corrosion on the low-quality stainless
steel.
[0453] The sample was removed from the calcium cell and filtered in
a glass-fiber filter. Then, the sample was placed in 1M HCl until
bubbling of acetylene ceased. The sample was filtered again. Then
the sample was placed in concentrated HCl and stirred for
approximately 1 minute. The sample was filtered again on a
glass-fiber filter. Next, alcohol (a mixture of methyl and ethyl
alcohol) was washed over the sample on the filter. Approximately
200 mL of alcohol was used. The sample was rinsed with this alcohol
10 times. Finally, the sample, on the filter, was placed in a
drying oven (80.degree. C.) for one hour. The sample was then
analyzed under the SEM and using Ramen spectroscopy.
[0454] The product of the elemental carbon material reaction
product is further shown in FIGS. 46-51 which are described more
below.
[0455] FIG. 46 is a first SEM image showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 10
microns). There are at least two interesting aspects of FIG. 46.
The first is that it shows a fin or projection of elemental carbon
material that appears to be roughly 90.degree. or perpendicular
from the surfaces it is attached to. The second aspect is that the
fin or projection seems to be very thin in the third dimension in
relation to the other two dimensions.
[0456] FIG. 47 is an SEM image showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 5
microns). FIG. 47 shows tiered graphene hexagons with increasing
particle size.
[0457] FIG. 48 is an SEM image showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 50
microns). The most interesting thing about FIG. 48 is the different
characteristics of the elemental carbon material at different
points on the particle. FIG. 48 appears to be one solid particle of
elemental carbon. On the left hand side towards the top it has a
textured appearance with material projecting from the surface. On
the right-hand side of the particle appears to be more smooth on
the surface. This represents the possibility of producing elemental
carbon with different characteristics in the same particle.
[0458] FIG. 49 has two SEM images showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 50 and 10
microns). The image on the left (A) is a two dimensional particle
of elemental carbon or graphene. The image on the right (B) shows a
magnified portion showing the depth or third dimension of the
particle. It appears to have four alternating layers that appear to
run in different directions. This figure also represents the
possibility of producing particles of elemental carbon with
different characteristics and orientations.
[0459] FIG. 50 has two SEM images showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 20
microns, A, and 10 microns, B). The most interesting thing about
FIG. 46 is the thickness or depth in the third dimension. FIG. 50
shows elemental carbon material that appears to be very thin in the
third dimension relative to the first two dimensions. This
elemental carbon also represents the possibility of producing
three-dimensional structures of elemental carbon that is mostly
"empty space".
[0460] FIG. 51 is an SEM image showing the carbon product in
Example 6 with use of a potentiostat, Sample D (scale bar 10
microns). FIG. 51 shows a piece of elemental carbon that is sp3
hybridized. It has very distinctly different characteristics than
the three-dimensional stacks of graphene-like material.
[0461] FIG. 52 shows an image of the bulk material produced in
Example 6. Although there is still a high percentage of amorphous
looking carbon, the amount of crystalline carbon is much higher
than anything seen in the prior thermal reactions (U.S. application
Ser. No. 14/213,533 and PCT Application PCT/US2014/028755). This is
roughly the same amount of material observed in the previous
examples. However, the crystal structure was different. There are
more well-defined and varying shapes including two dimensional
sheets or plates of elemental carbon. The fibrous material seen on
the right side of the image is contamination from the filter used
during the separation and purification operations.
[0462] FIG. 53 shows a magnified image of the elemental carbon
crystalline material seen in the upper right-hand quarter of FIG.
65. Note the well-defined two-dimensional layers of this
material.
[0463] FIG. 54 provides a further magnified image of FIG. 53 at a
scale 10 .mu.m. This more clearly shows the stacked two dimensional
structure of the material.
[0464] FIG. 55 provides an image of a large composite piece of
elemental carbon at a scale of 100 .mu.m. This three-dimensional
structure is a composite of smaller two dimensional plate-like
pieces of elemental carbon. This material represents a very high
surface area three-dimensional material.
[0465] FIG. 56 provides a magnified image of FIG. 55. Note how the
two dimensional elemental carbon pieces form the structure.
[0466] FIG. 57 shows the Raman spectra at seven different sites
taken from a sample of the material produced in Example 6.
Example 7
[0467] The apparatus was for an ethanol electrochemical reaction
with potentiostat, 3, single CaC.sub.2 crystal.
[0468] A Zn/ZnCl.sub.2.parallel.CaC.sub.2/CaCl.sub.2 was set up
using saturated salts on both sides in dry ethanol. The zinc is in
the form of a zinc rod. A single CaC.sub.2 crystal was put in the
CaCl.sub.2 cell. The Ag/AgCl.sub.2 reference cell was placed in the
zinc cell. The potentiostat and an ammeter were connected in series
between the zinc and CaC.sub.2 electrodes.
[0469] The objectives were to continue with gather information and
data to improve the operation of the electrolysis reaction system,
and produce carbon material.
[0470] The reaction that was expected to occur was:
CaC.sub.2+ZnCl.sub.2.fwdarw.2C+CaCl.sub.2+Zn (1)
[0471] In this reaction, Zn.sup.+2 is reduced to elemental zinc.
The carbide anion is oxidized to elemental carbon. The standard
reduction potential of either half-cell is not known in ethanol. It
has been observed that this reaction occurs spontaneously at room
temperature.
[0472] With an applied potential of 0V, a current of 150 uA was
measured. This is the highest galvanic current measured thus far.
When a voltage was applied, the current did not change until a
voltage of 2.20V. Then, the current decreased rapidly and changed
sign to -150 uA at 2.50V.
[0473] The current steadily increased to approximately 1000 uA. The
zinc cell appeared to be clear, having consumed the zinc chloride,
presumably. More zinc chloride was added. The current increased to
1500 uA. The cell quickly cleared again, and again, more zinc
chloride was added. The current increased to 1800 uA. The cell was
left overnight.
[0474] The next day, the current had reached 2,300 uA. The piece
was removed. The bottom of the piece had noticeable black layer on
it. Upon the addition of acid in methanol, the black pieces fell
off. There was no noticeable acetylene smell until the acid mixture
was added.
[0475] The material was filtered after sitting in HCl over several
days. Large pieces were still visible.
Example 8
[0476] The main objective for Example 8, was to react aluminum
carbide to produce elemental carbon using the potentiostat to apply
a forced external voltage. Nearly the same apparatus and the same
experimental procedure as Example 6 were used. The changes made
were to accommodate the aluminum carbide which is in the form of
-325 mesh fine particle size power. The aluminum carbide used was:
Sigma-Aldrich; Aluminum Carbide; Powder, -325 mesh, 99%; Product
number: 241837; CAS: 1299-86-1.
[0477] The changes to the apparatus are made to the carbide cell
and the anode which held the carbide. First, the tea ball strainer
was replaced with a platinum basket supporting a platinum crucible
to hold the small particle size, powder like aluminum carbide. The
platinum holder replaced the stainless steel holder to eliminate
any surface effects between the holder and the carbide. Normally
the calcium carbide is placed in the platinum mesh basket. But with
the small particle size of the aluminum carbide, the mesh platinum
basket supported a solid crucible which held the aluminum carbide.
A smaller diameter hole was drilled in a new rubber stopper acting
as a cap for the carbide cell. A platinum wire was fed tightly
through the opening in a loop was fabricated on the end of the wire
inside of the cell. The basket, which had a holding rod attached
with a hook, was connected to the platinum wire exiting the carbide
cell. The platinum wire would then be connected to the potentiostat
and amp meter. It had been observed in previous experiments that no
vapor was being produced which needed to be vented from the carbide
cell. Therefore, there was no longer need for the bubbler or the
hollow tube exiting the cell to vent any vapors formed.
[0478] The reaction that is expected to occur is:
Al.sub.4C.sub.3+6ZnCl.sub.2.fwdarw.3C+4AlCl.sub.3+6Zn
In this reaction, Zn.sup.+2 is reduced to elemental zinc. The
carbide anion is oxidized to elemental carbon. The standard
reduction potential of either half-cell is not known in ethanol. It
has been observed that this reaction occurs spontaneously at room
temperature. CaCl.sub.2 was added to the aluminum cell to provide
conductivity and available chloride anions.
[0479] A forced external voltage of 1.0 V was applied. Initially, a
current of 580 uA was measured. The current steadily increases from
this value. All of the excess ZnCl.sub.2 dissolved or was consumed
within a few minutes. The aluminum cell appears opaque white.
Eventually, a clear layer formed on the bottom of the aluminum
cell. It should be noted, since Al.sub.4C.sub.3 is a fine powder,
so no agitation was used in the aluminum cell, as it would cause
the carbide to come out of the crucible.
[0480] Products of reaction were subjected to the same cleaning and
purification operations as Example 6 with one exception. Due to the
problem with contamination, the fiber filter was replaced with a
silver filter. The silver filter provided the same high flow rate
efficiency but was much more structurally solid and did not
contaminate the samples produced. One note with the aluminum
carbide reaction is that less elemental carbon was recovered due to
the stoichiometry of the chemical reaction. Because less was
recovered, the analysis was performed on the sample collected on
the filter. Therefore, an accurate weight for this experiment could
not be determined. An estimate for the recovery would be roughly
one tenth of a gram. The sample was analyzed using the SEM and
Ramen spectroscopy.
[0481] FIG. 68 is an SEM image of the bulk sample produced from
Example 8. It appears that a high percentage of the material
produced was amorphous carbon with a smaller percentage of
crystalline carbon like the thermal reactions (U.S. application
Ser. No. 14/213,533 and PCT Application PCT/US2014/028755). It did
appear that a slightly larger amount of the material was
crystalline as opposed to amorphous as produced in the thermal
reactions. However, this is unclear because the aluminum carbide
was in the form of -325 mesh powder.
[0482] FIG. 69 is an image of the crystalline material produced in
Example 8. The two things of note are the piece of curved two
dimensional material and the shape, structure, and overall
appearance of the other piece of elemental carbon. This SEM images
unique in that two pieces of elemental carbon with characteristics
that have not yet been observed are seen side by side.
[0483] FIG. 70 is the Raman spectra of the products produced by
Example 8. This picture shows evidence of the standard sp2 carbon
peaks. Also, towards the left side of the spectrum, there are
additional peaks that are not well defined. These peaks may
indicate additional forms of carbon, but could also be contaminants
or undesired products of reaction that were not removed and the
separation and purification operations or simply contaminates in
the carbide. The separation and purification operations were
difficult in this experiment due to the small particle size of the
calcium carbide used as a reactant.
Example 9
[0484] The main objective for Example 9 was to perform an
experiment where the standard carbide cell including calcium
carbide immersed in a solution of ethanol and calcium chloride was
reacted with a cathode of elemental tin immersed in a solution of
ethanol and stannous chloride. The second objective of this
experiment was to apply a forced external voltage to this reaction
system using the potentiostat.
[0485] The same apparatus and procedure was used for Example 9 as
was used in Example 8 with three differences. The first difference
is that the elemental zinc cathode immersed in a solution of
ethanol and zinc chloride was replaced with an elemental tin
cathode immersed in a solution of ethanol and stannous chloride.
The second was that Example 9 used calcium carbide instead of
aluminum carbide. The third was in the platinum carbide holder used
as part of the anode in the particle size of the carbide. The
carbide holder was altered simply by removing the solid crucible
from the mesh basket. The mesh basket includes a mesh open top
cylinder roughly 3/4 of an inch in diameter and 2 inches high. One
solid piece of calcium carbide roughly 2 cm was placed inside the
holder.
[0486] The reaction that is expected to occur is:
CaC.sub.2+SnCl.sub.2.fwdarw.2C+CaCl.sub.2+Sn
In this reaction, Sn.sup.+2 is reduced to elemental zinc. The
carbide anion is oxidized to elemental carbon. The standard
reduction potential of either half-cell is not known in ethanol. It
has been observed that this reaction occurs spontaneously at room
temperature. CaCl.sub.2 was added to the aluminum cell to provide
conductivity and available chloride anions.
[0487] A forced external voltage of 1.0 V was applied. Initially, a
current of 5100 uA was measured. The current steadily increases
from this value. All of the excess ZnCl.sub.2 dissolved or was
consumed within a few minutes. This current stayed constant for
approximately 5 hours, then steadily rose to 8000 uA.
[0488] At the conclusion of the reaction, the products of the
calcium cell were filtered on a silver membrane filter, then
treated with HCl. The product appears to be a black powder.
[0489] FIG. 61 shows an SEM image of elemental carbon produced in
Example 9. The carbon appears to have a stacked nature similar to
that of the hexagonal shapes sheets. However it is different in
that it is not consistent and seems to be "bunched up".
[0490] FIG. 62 shows an SEM image of the carbon bent at an acute
angle. This is a unique image in that it shows the material on
edge. In this orientation, you can clearly see the nature of the
angle of the material.
[0491] FIG. 63 represents the Raman spectra for the material
produced in Example 9.
Example 10
[0492] Example 10 represents an experiment performed using an
updated design of a newly fabricated small bench scale glass
reaction apparatus. The new reactor can be seen in FIG. 18. There
were several improvements and changes made to the new reactor. The
main purpose for the new reactor design was to accommodate an ion
exchange membrane used in place of the glass fritted filter from
the reactor in FIG. 17. The ion exchange membrane not only prevents
solid materials from migrating between the cells, it does not
permit mass transfer at all. It is also selective with respect to
charge of the ions that are capable of passing through the
membrane. For instance, one membrane will permit cations from
passing through and not permit anions from passing. Another
membrane will permit and ions and resist cations from passing
through.
[0493] Since the ion exchange membrane will need to be replaced
whereas the glass fitted filter did not, the reactor was designed
as two pieces connected with a clamp and sealed together with an
O-ring gasket and vacuum grease. This connection was made in the
salt bridge where the ion exchange membrane can be replaced and
altered between experiments. Also in the salt bridge was a larger
stopcock to accommodate the larger diameter of the salt bridge and
permit greater migration of ions from one cell to the other. A
further design change of the new reactor is that the diameter of
the two cells was increased several centimeters to facilitate
better agitation from the stirring bar and accommodate a wider
range of anodes and cathodes for future testing.
[0494] The final change of the reactor design was to add additional
ports to each cell on the opposite side of the connection to the
salt bridge. These ports enter the cell at a 45.degree. angle and
can be sealed using a glass plug due to the glass ground joint.
These ports are to accommodate reference electrodes or to allow
access to the cell or any future reactions.
[0495] The reaction performed was the standard
Zn/ZnCl.sub.2.parallel.CaC.sub.2/CaCl.sub.2 was set up using
saturated salts on both sides in dry ethanol. The zinc is in the
form of a zinc rod. The zinc rod was submerged into saturated zinc
chloride in ethanol along with a Ag/AgCl.sub.2 reference electrode.
CaC.sub.2 is available as a single large piece (about 2 cm). It was
placed in a platinum crucible that was placed in the platinum cage.
The cage is used to provide support for the crucible. The cage and
crucible were submerged in a solution of CaCl.sub.2 in ethanol. The
potentiostat was hooked up with the data acquisition system. A
voltage of 1.0 V was applied.
[0496] The reaction that is expected to occur is:
CaC.sub.2+ZnCl.sub.2.fwdarw.2C+CaCl.sub.2+Zn
In this reaction, Zn.sup.+2 is reduced to elemental zinc. The
carbide anion is oxidized to elemental carbon. The standard
reduction potential of either half-cell is not known in ethanol. It
has been observed that this reaction occurs spontaneously at room
temperature. CaCl.sub.2 was added to the calcium carbide cell to
provide conductivity and available chloride anions.
[0497] After being allowed to run for four several days, the
calcium piece turned opaque white and appeared to form layers. When
the piece was placed in acid, some black pieces fell off of the
larger white mass, and the white mass appeared to be unaffected by
the acid. However, after setting in the acid for 30 minutes, the
piece eventually dissolved. Very little black material
remained.
[0498] By the end of the reaction, the calcium cell was a clear
yellow color. The zinc cell was a translucent white. The zinc
growth on the rod was considerable, and visible through the
solution with a flashlight. The ion exchange membrane gained a
brownish color on the calcium side and a black color on the zinc
side. The black color, however, was not present at the point of
liquid contact. It was above the level of the liquid.
[0499] FIG. 64 shows an SEM image at a scale of 200 .mu.m of the
products of reaction from Example 10 or the first reaction using an
exchange membrane with the updated reactor. The material has an
appearance similar to that of the amorphous carbon. However, as
will be seen in the next several figures, this material appears to
be crystalline with an appearance of the surface of the material
being "chewed up".
[0500] FIG. 65 shows a magnified image of the material seen in FIG.
64 at a scale of 30 .mu.m. This more clearly shows that the
material is crystalline elemental carbon and not the amorphous
elemental carbon.
[0501] FIG. 66 shows an even more magnified image of the material
seen in FIGS. 65 and 66 at a scale of 10 .mu.m. It is clear from
this image that the material is crystalline and not the amorphous
carbon.
[0502] FIG. 67 shows the Ramen spectra from the analysis of the
products of Example 10.
Example 11: Reaction of Calcium Carbide with Zinc Chloride in
Methanol
[0503] The organic solvent reaction was a relatively simple
reaction used to show that the calcium carbide was conductive and
would react at room temperature in a solution of a solvent and
dissolved metallic salt.
[0504] The experiment was prepared in the controlled argon
atmosphere of the glove box. 300 mL of dried methanol was placed in
a standard 500 mL Erlenmeyer flask. 100 g of zinc chloride was also
added to the Erlenmeyer flask. A magnetic stir bar was also placed
in the flask and a rubber stopper was fitted to seal it. Calcium
carbide was crushed to a coarse particle size of roughly less than
1 cm. The calcium carbide was then added to the flask and the
rubber stopper placed on it to seal. The sealed flask now contained
20 g of calcium carbide, 300 mL of dried methanol, 100 g of zinc
chloride, and a magnetic stir bar.
[0505] The sealed flask was removed from the glove box and placed
on a stir plate. The reaction was allowed to proceed for three
days. It was then stopped and removed from the stir plate. The
flask was opened and the contents subjected to the standard
separation and purification operations. There was very little
product remaining after the cleaning and separation procedure. This
was expected due to the conductivity of calcium carbide and the
expected low rate of reaction. There was enough material to be
analyzed under the SEM and with Ramen spectroscopy.
[0506] FIG. 68 shows an image of an elemental carbon material that
appears to be two dimensional and very thin. This is evident from
the fact that the electron beam can "see" through the material.
[0507] FIG. 69 shows a very consistent stack of elemental carbon
hexagonal sheets with a cross-sectional area of roughly 20 cm. This
hexagonal stack is sitting on top of a larger piece of what appears
to be stacked two dimensional elemental carbon.
[0508] FIG. 70 shows a second well-defined stack of hexagonal
sheets of two-dimensional carbon. This image, along with FIG. 69,
shows that this reaction is possible at room temperature and
atmospheric pressure.
[0509] FIG. 71 shows the Raman analysis from a sample of the
products of Example 11. This further shows that it is possible to
produce elemental carbon at room temperature via this reaction
technology.
Example 12
[0510] Example 12 describes small particle size graphene
exfoliation in the ultrasonic bath with a low sonication
energy.
[0511] A small portion (about 0.1 g) of the cleaned products were
placed in glass centrifuge tubes which were then filled with NMP.
The centrifuge tube was then immersed a lower power ultrasonic bath
(Cole-Parmer Model: 8854). The graphene in NMP was sonicated for
four hours and then removed from the bath.
[0512] The tubes were then centrifuged and examined. The NMP in the
tubes with the smaller particle size sample had exfoliated graphene
that remained in solution.
INSTRUMENTATION: The following instruments were used for the
working examples: Hitachi S-4700 Scanning Electron Microscope and a
Renishaw InVia Raman Microscope.
* * * * *