U.S. patent application number 12/589470 was filed with the patent office on 2010-09-23 for composite material.
This patent application is currently assigned to Tsinghua University. Invention is credited to Shou-Shan Fan, Kai-Li Jiang, Qun-Qing Li, Jia-Ping Wang.
Application Number | 20100239849 12/589470 |
Document ID | / |
Family ID | 42737921 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100239849 |
Kind Code |
A1 |
Wang; Jia-Ping ; et
al. |
September 23, 2010 |
Composite material
Abstract
The disclosure related to a composite material. The composite
material includes a free-standing carbon nanotube structure having
a plurality of carbon nanotubes and a number of nanoparticles. The
nanoparticles are spaced from each other and coated on a surface of
each of the carbon nanotubes of the carbon nanotube structure.
Inventors: |
Wang; Jia-Ping; (Beijing,
CN) ; Jiang; Kai-Li; (Beijing, CN) ; Li;
Qun-Qing; (Beijing, CN) ; Fan; Shou-Shan;
(Beijing, CN) |
Correspondence
Address: |
Altis Law Group, Inc.;ATTN: Steven Reiss
288 SOUTH MAYO AVENUE
CITY OF INDUSTRY
CA
91789
US
|
Assignee: |
Tsinghua University
Beijing
CN
HON HAI PRECISION INDUSTRY CO., LTD.
Tu-Cheng
TW
|
Family ID: |
42737921 |
Appl. No.: |
12/589470 |
Filed: |
October 23, 2009 |
Current U.S.
Class: |
428/323 ;
977/742; 977/773 |
Current CPC
Class: |
B82Y 30/00 20130101;
B01J 21/185 20130101; B01J 35/002 20130101; Y10T 428/2927 20150115;
B01J 35/0013 20130101; C01B 32/174 20170801; Y10T 428/25 20150115;
B82Y 40/00 20130101 |
Class at
Publication: |
428/323 ;
977/742; 977/773 |
International
Class: |
B32B 5/16 20060101
B32B005/16 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2009 |
CN |
200910106339.9 |
Claims
1. A composite material comprising: a free-standing carbon nanotube
structure comprising a plurality of carbon nanotubes; and a
plurality of nanoparticles spaced from each other and coated on a
surface of each of the carbon nanotubes of the carbon nanotube
structure.
2. The composite material as claimed in claim 1, wherein a distance
between two adjacent nanoparticles are larger than a diameter of
each of the nanoparticles, the diameter of each of the
nanoparticles is in a range from about 1 nanometer to about 100
nanometers.
3. The composite material as claimed in claim 1, wherein the carbon
nanotube structure is a drawn carbon nanotube film comprising a
plurality of carbon nanotubes substantially oriented along a
direction and joined end to end.
4. The composite material as claimed in claim 1, further comprising
a supporting element, wherein edges of the carbon nanotube
structure are located on the supporting element, and a center
portion of the carbon nantoube structure is suspended.
5. The composite material as claimed in claim 4, wherein the
supporting element is a frame.
6. The composite material as claimed in claim 1, wherein the carbon
nanotube structure is a pressed carbon nanotube film comprising a
plurality of carbon nanotubes, an angle between a primary alignment
direction of the carbon nanotubes and a surface of the pressed
carbon nanotube film is approximately 0 degrees to approximately 15
degrees.
7. The composite material as claimed in claim 1, wherein the carbon
nanotube structure is a flocculated carbon nanotube film comprising
a plurality of long, curved, disordered carbon nanotubes entangled
with each other.
8. The composite material as claimed in claim 1, wherein the carbon
nanotube structure is a linear carbon nanotube structure comprising
a plurality of carbon nanotube wires substantially parallel to each
other.
9. The composite material as claimed in claim 1, wherein the carbon
nanotube structure further comprises a plurality of carbon nanotube
wires substantially oriented along a same direction or
substantially oriented around an axial direction of the CNT
wire.
10. The composite material as claimed in claim 1, wherein the
carbon nanotube structure further comprises at least one carbon
nanotube wire and at least one carbon nanotube film, the at least
one carbon nanotube wire is located on a surface of the at least
one carbon nanotube film.
11. The composite material as claimed in claim 1, wherein the
carbon nanotube structure is a twisted carbon nanotube wire.
12. The composite material as claimed in claim 1, wherein the
carbon nanotube structure is an untwisted carbon nanotube wire.
13. The composite material as claimed in claim 1, wherein the
nanoparticles are selected from the group consisting of metal
nanoparticles, non-metal nanoparticles, alloy nanoparticles,
metallic oxide nanoparticles, polymer nanoparticles, and any
combination thereof.
14. The composite material as claimed in claim 1, wherein each of
the nanoparticles is adhered to a surface of at least one carbon
nanotube.
15. The composite material as claimed in claim 1, wherein each
carbon nanotube is totally wrapped by one of the nanoparticles if
each carbon nanotube is smaller than each nanoparticle.
16. A composite material comprising: a free-standing carbon
nanotube structure comprising a plurality of carbon nanotubes; and
a plurality of nanoparticles spaced from each other and coated on a
surface of each of the carbon nanotubes, wherein each of the
nanoparticle wraps a part of a surface of at least one carbon
nanotube.
17. The composite material as claimed in claim 16, wherein each
carbon nanotube is totally wrapped by one of the nanoparticles if
each carbon nanotube is smaller than each nanoparticle.
Description
RELATED APPLICATIONS
[0001] This application claims all benefits accruing under 35
U.S.C. .sctn.119 from China Patent Application No. 200910106339.9,
filed on Mar. 21, 2009 in the China Intellectual Property Office.
This application is related to applications entitled
"NANO-MATERIALS", filed ______ (Atty. Docket No. US24930); "METHOD
FOR MAKING NANOWIRE STRUCTURE", filed ______ (Atty. Docket No.
US21323); "METHOD FOR MAKING COMPOSITE MATERIAL", filed ______
(Atty. Docket No. US28706); "CARBON NANOTUBE COMPOSITE AND METHOD
FOR FABRICATING THE SAME", filed on Aug. 13, 2009 (Atty. Docket No.
US20920).
BACKGROUND
[0002] 1. Technical Field
[0003] The disclosure relates to a composite material, and
particularly to a carbon nanotube composite material.
[0004] 2. Description of Related Art
[0005] Many novel properties are beyond traditional theories when
the materials are nano-sized, which may reasonably make
nano-materials the representative of modern science and technology.
The potential research is highly sought because of their distinct
catalytic, electronic, magnetic, and luminescent properties. A
composite material having carbon nanotubes as reinforcement and as
an electrical conductor as well as nano-particles have broad
applications in the field of microelectronics, material science,
biology, and chemistry because of good anti-static performance,
microwave absorbing capability, electromagnetic shielding ability,
and so on. However, the nano-particles are prone to agglomerate
together. Methods have been developed to manufacture a composite
which includes a plurality of carbon nanotubes with nano-particles
uniformly distributed on the surface of the carbon nanotubes.
[0006] A carbon nanotube composite material includes a plurality of
carbon nanotube powders and tricobalt tetraoxide (Co.sub.3O.sub.4)
particles coated on the surface of the carbon nanotube powders. The
carbon nanotubes and Co.sub.3O.sub.4 particles form a composite
nano-powder. A typical method for making the composite nano-powder
includes:
[0007] (a1) putting the carbon nanotube powders into a strong
nitric acid for about 6 to about 8 hours;
[0008] (a2) introducing an active functional group, for example,
hydroxyl group or carboxyl group on the surface of the carbon
nanotube powder;
[0009] (a3) using deionized water to clean the carbon nanotube
powders which is activated by an active functional group;
[0010] (a4) providing a mixture which is made by dissolving a
cobalt (II) nitrate hexahydrate into an ethanol solution;
[0011] (a5) immersing the carbon nanotube powders into the mixture
and vibrating by ultrasound for about 15 to about 60 minutes, so
that the cobalt(II) nitrate hexahydrate are adsorbed on the surface
of the carbon nanotube powders;
[0012] (a6) pouring the mixture into a silicone oil for about 5 to
10 hours to decompose the cobalt(II) nitrate hexahydrate into
Co.sub.3O.sub.4 particles to obtain the carbon nanotube composite
material coated by Co.sub.3O.sub.4 particles; and
[0013] (a7) cleaning the carbon nanotube composite material by
ethane and ethanol.
[0014] However, the above mentioned method is complicated, costly,
and not suitable for mass production. Furthermore, strong nitric
acid can be prone to pollute the environment.
[0015] A composite film material includes a carbon nanotube film on
a metal substrate and nickel (Ni) nano-particles. The nickel (Ni)
nano-particles are deposited on the carbon nanotube film. A method
for making the carbon nanotube composite film material
includes:
[0016] (b1) providing a metal substrate and a plurality of carbon
nanotubes;
[0017] (b2) polishing and degreasing the metal substrate;
[0018] (b3) putting the carbon nanotubes into an acetylacetone
solution and ultrasonically vibrating the solution to obtain a
carbon nanotube suspension;
[0019] (b4) using the metal substrate as a cathode and supplying a
direct current into the suspension to deposit the carbon nanotubes
on the surface of the metal substrate and forming a carbon nanotube
film on the metal substrate; and
[0020] (b5) placing the metal substrate on a carbon nanotube film
deposited into a plating solution with Ni, and coating Ni
nano-particles on the surface of the carbon nanotube film by
electroplating to obtain the composite film material.
[0021] However, in this method, the Ni particles are prone to
agglomerate together. Furthermore, the method is complicated,
costly, and not suitable for mass production.
[0022] Therefore, there is room for improvement within the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Many aspects of the embodiments can be better understood
with references to the following drawings. The components in the
drawings are not necessarily drawn to scale, the emphasis instead
being placed upon clearly illustrating the principles of the
embodiments. Moreover, in the drawings, like reference numerals
designate corresponding parts throughout several views.
[0024] FIG. 1 is a schematic view of one embodiment of a composite
material.
[0025] FIG. 2 shows a Scanning Electron Microscope (SEM) image of a
drawn carbon nanotube film.
[0026] FIG. 3 is a schematic structural view of a carbon nanotube
segment of the drawn carbon nanotube film of FIG. 2.
[0027] FIG. 4 is an SEM image of a pressed carbon nanotube film of
carbon nanotube structure, wherein carbon nanotubes of the pressed
carbon nanotube film are arranged along a same direction.
[0028] FIG. 5 is an SEM image of a pressed carbon nanotube film,
wherein carbon nanotubes of the pressed carbon nanotube film are
arranged along different directions.
[0029] FIG. 6 is an SEM image of a flocculated carbon nanotube film
with carbon nanotubes entangled with each other therein.
[0030] FIG. 7 is an SEM image of an untwisted carbon nanotube
wire.
[0031] FIG. 8 is an SEM image of a twisted carbon nanotube
wire.
[0032] FIG. 9 is a flow chart of one embodiment of a method for
fabricating a composite material.
[0033] FIG. 10 is a schematic flow chart of the method for
fabricating the composite material of FIG. 9.
[0034] FIG. 11 is an SEM image of a composite material formed by
activating a first reacting material layer.
[0035] FIG. 12 is an SEM image of composite material formed by
activating a second reacting material layer.
[0036] FIG. 13 is an SEM image of a composite material formed by
activating a third reacting material layer.
[0037] FIG. 14 is a Transmission Electron Microscopy (TEM) image of
the composite material of FIG. 11.
DETAILED DESCRIPTION
[0038] Carbon Nanotube Composite Material
[0039] Referring to FIG. 1, a carbon nanotube composite material 10
includes a carbon nanotube structure 100 and a plurality of
nanoparticles 104. The carbon nanotube structure 100 includes a
plurality of carbon nanotubes adhered to each other and together by
van der Waals attractive forces to form a free-standing structure.
The carbon nanotube structure 100 can be a carbon nanotube film
structure or a carbon nanotube wire structure. The nanoparticles
104 are uniformly distributed in the carbon nanotube structure
100.
[0040] The free-standing carbon nanotube structure means the carbon
nanotube structure can maintain a certain shape without any
supporter, which is different from a powder or liquid form. Since
the carbon nanotube structure includes the plurality of carbon
nanotubes combined by Van der Waals attractive force therebetween,
the certain shape is formed. The carbon nanotube structure is made
only of carbon nanotubes. The carbon nanotubes can be orderly or
disorderly arranged. The carbon nanotubes in the carbon nanotube
structure can be single-walled, double-walled, or multi-walled
carbon nanotubes. A diameter of each single-walled carbon nanotube
ranges from about 0.5 nanometers (nm) to about 50 nm. A diameter of
each double-walled carbon nanotube ranges from about 1 nm to about
50 nm. A diameter of each multi-walled carbon nanotube ranges from
about 1.5 nm to about 50 nm. The length of each carbon nanotube is
above 50 micrometers (.mu.m). In one embodiment, the length of the
carbon nanotubes ranges from about 200 .mu.m to 900 .mu.m.
[0041] The carbon nanotube structure can be a carbon nanotube film
structure with a thickness ranging from about 0.5 nm to about 1
millimeter (mm). The carbon nanotube film structure can include at
least one carbon nanotube film. The carbon nanotube structure can
also be a linear carbon nanotube structure with a diameter ranging
from about 0.5 nm to about 1 mm. The carbon nanotube structure can
also be a combination of the carbon nanotube film structure and the
linear carbon nanotube structure. It is understood that any carbon
nanotube structure described can be used with all embodiments.
[0042] Drawn Carbon Nanotube Film
[0043] In one embodiment, the carbon nanotube film structure
includes at least one drawn carbon nanotube film. A film can be
drawn from a carbon nanotube array, to form a drawn carbon nanotube
film. Examples of drawn carbon nanotube film are taught by U.S.
Pat. No. 7,045,108 to Jiang et al., and WO 2007015710 to Zhang et
al. The drawn carbon nanotube film includes a plurality of
successive and oriented carbon nanotubes joined end-to-end by van
der Waals attractive force therebetween. The drawn carbon nanotube
film is a free-standing film. Referring to FIGS. 2 to 3, each drawn
carbon nanotube film includes a plurality of successively oriented
carbon nanotube segments 143 joined end-to-end by van der Waals
attractive force therebetween. Each carbon nanotube segment 143
includes a plurality of carbon nanotubes 145 substantially parallel
to each other, and combined by van der Waals attractive force
therebetween. The carbon nanotubes 145 in the drawn carbon nanotube
film are substantially oriented along a preferred orientation. The
carbon nanotube film can be treated with an organic solvent to
increase the mechanical strength and toughness of the carbon
nanotube film and reduce the coefficient of friction of the carbon
nanotube film. A thickness of the carbon nanotube film can range
from about 0.5 nm to about 100 .mu.m.
[0044] A method of making a drawn carbon nanotube film includes the
steps of: providing an array of carbon nanotubes; and pulling out a
drawn carbon nanotube film from the array of carbon nanotubes.
Pulling can be aided by the use of a tool such as adhesive tape,
pliers, tweezers, or other tools allowing multiple carbon nanotubes
to be gripped and pulled simultaneously.
[0045] The drawn carbon nanotube film can be formed by selecting
one or more carbon nanotubes having a predetermined width from the
array of carbon nanotubes and pulling the carbon nanotubes at a
uniform speed to form carbon nanotube segments that are joined end
to end to achieve a uniform drawn carbon nanotube film.
[0046] The carbon nanotube segments can be selected by using the
tool allowing multiple carbon nanotubes to be gripped and pulled
simultaneously to contact with the array of carbon nanotubes. The
pulling direction can be substantially perpendicular to the growing
direction of the array of carbon nanotubes.
[0047] More specifically, during the pulling process, as the
initial carbon nanotube segments are drawn out, other carbon
nanotube segments are also drawn out end to end due to van der
Waals attractive forces between ends of adjacent segments. This
process of pulling produces a substantially continuous and uniform
carbon nanotube film having a predetermined width.
[0048] The carbon nanotube film structure can include at least two
stacked carbon nanotube films. In other embodiments, the carbon
nanotube structure can include two or more coplanar carbon nanotube
films, and can include layers of coplanar carbon nanotube films.
Additionally, when the carbon nanotubes in the carbon nanotube film
are substantially aligned along one preferred orientation (e.g.,
the drawn carbon nanotube film), an angle can exist between the
orientation of carbon nanotubes in adjacent films, whether they are
stacked or adjacent. Adjacent carbon nanotube films can be combined
only by the van der Waals attractive force therebetween. The number
of the layers of the carbon nanotube films is not limited. However,
as the thickness of the carbon nanotube structure increases, the
specific surface area decreases. An angle between the aligned
directions of the carbon nanotubes in two adjacent carbon nanotube
films can range from about 0 degrees to about 90 degrees. When the
angle between the aligned directions of the carbon nanotubes in
adjacent carbon nanotube films is larger than 0 degrees, a
microporous structure is defined by the carbon nanotubes. The
carbon nanotube structure in an embodiment employing these films
will have a plurality of micropores. The micropore has a diameter
which can range from about 1 nm to about 0.5 .mu.m. Stacking the
carbon nanotube films will also add to the structural integrity of
the carbon nanotube structure.
[0049] Pressed Carbon Nanotube Film
[0050] In another embodiment, the carbon nanotube film structure
can include at least one pressed carbon nanotube film. Referring to
FIGS. 4 and 5, the pressed carbon nanotube film can be a
free-standing carbon nanotube film. The carbon nanotubes in the
pressed carbon nanotube film can be substantially arranged along a
same direction (see FIG. 4) or substantially arranged along
different directions (see FIG. 5). The carbon nanotubes in the
pressed carbon nanotube film can rest upon each other. Adjacent
carbon nanotubes are attracted to each other and combined by van
der Waals attractive force. An angle between a primary alignment
direction of the carbon nanotubes and a surface of the pressed
carbon nanotube film is about 0 degrees to about 15 degrees. The
greater the pressure applied, the smaller the angle formed. When
the carbon nanotubes in the pressed carbon nanotube film are
substantially arranged along different directions, the carbon
nanotube structure can be isotropic. The thickness of the pressed
carbon nanotube film ranges from about 0.5 nm to about 1 mm.
Examples of pressed carbon nanotube film are taught by US
application 20080299031A1 to Liu et al.
[0051] The pressed carbon nanotube film can be executed by
providing an array of carbon nanotubes formed on a substrate; and
providing a pressing device to press the array of carbon nanotubes,
thereby forming the pressed carbon nanotube film.
[0052] Flocculated Carbon Nanotube Film
[0053] In another embodiment, the carbon nanotube film structure
includes a flocculated carbon nanotube film. Referring to FIG. 6,
the flocculated carbon nanotube film can include a plurality of
long, curved, disordered carbon nanotubes entangled with each
other. Further, the flocculated carbon nanotube film can be
isotropic. The carbon nanotubes can be substantially uniformly
dispersed in the carbon nanotube film. Adjacent carbon nanotubes
are acted upon by van der Waals attractive force to form an
entangled structure with micropores defined therein. It is
understood that the flocculated carbon nanotube film is very
porous. Sizes of the micropores can be less than 10 .mu.m. The
porous nature of the flocculated carbon nanotube film will increase
the specific surface area of the carbon nanotube structure.
Further, due to the carbon nanotubes in the carbon nanotube
structure being entangled with each other, the carbon nanotube
structure employing the flocculated carbon nanotube film has
excellent durability, and can be fashioned into desired shapes with
a low risk to the integrity of the carbon nanotube structure.
[0054] The flocculated carbon nanotube film can be executed by
providing carbon nanotubes, flocculating the carbon nanotubes in a
solvent to acquire a carbon nanotube flocculated structure,
separating the carbon nanotube flocculated structure from the
solvent, and shaping the separated carbon nanotube flocculated
structure into the flocculated carbon nanotube film in which the
carbon nanotubes are entangled with each other and isotropic.
[0055] Linear Carbon Nanotube Structure
[0056] In other embodiments, the linear carbon nanotube structure
includes carbon nanotube wires and/or carbon nanotube cables.
[0057] The carbon nanotube wire can be untwisted or twisted.
Treating the drawn carbon nanotube film with a volatile organic
solvent can form the untwisted carbon nanotube wire. Specifically,
the organic solvent is applied to soak the entire surface of the
drawn carbon nanotube film. During the soaking, adjacent parallel
carbon nanotubes in the drawn carbon nanotube film will bundle
together, due to the surface tension of the organic solvent as it
volatilizes, and thus, the drawn carbon nanotube film will be
shrunk into untwisted carbon nanotube wire. Referring to FIG. 7,
the untwisted carbon nanotube wire includes a plurality of carbon
nanotubes substantially oriented along a same direction (i.e., a
direction along the length of the untwisted carbon nanotube wire).
The carbon nanotubes are substantially parallel to the axis of the
untwisted carbon nanotube wire. More specifically, the untwisted
carbon nanotube wire includes a plurality of successive carbon
nanotube segments joined end to end by van der Waals attractive
force therebetween. Each carbon nanotube segment includes a
plurality of carbon nanotubes substantially parallel to each other,
and combined by van der Waals attractive force therebetween. The
carbon nanotube segments can vary in width, thickness, uniformity,
and shape. Length of the untwisted carbon nanotube wire can be
arbitrarily set as desired. A diameter of the untwisted carbon
nanotube wire ranges from about 0.5 nm to about 100 .mu.m.
[0058] The twisted carbon nanotube wire can be formed by twisting a
drawn carbon nanotube film using a mechanical force to turn the two
ends of the drawn carbon nanotube film in opposite directions.
Referring to FIG. 8, the twisted carbon nanotube wire includes a
plurality of carbon nanotubes helically oriented around an axial
direction of the twisted carbon nanotube wire. More specifically,
the twisted carbon nanotube wire includes a plurality of successive
carbon nanotube segments joined end to end by van der Waals
attractive force therebetween. Each carbon nanotube segment
includes a plurality of carbon nanotubes substantially parallel to
each other, and combined by van der Waals attractive force
therebetween. The length of the carbon nanotube wire can be set as
desired. A diameter of the twisted carbon nanotube wire can be from
about 0.5 nm to about 100 .mu.m. Further, the twisted carbon
nanotube wire can be treated with a volatile organic solvent after
being twisted. After being soaked by the organic solvent, the
adjacent carbon nanotubes in the twisted carbon nanotube wire will
bundle together, due to the surface tension of the organic solvent
when the organic solvent volatilizes. The specific surface area of
the twisted carbon nanotube wire will decrease, while the density
and strength of the twisted carbon nanotube wire will increase.
[0059] The carbon nanotube cable includes two or more carbon
nanotube wires. The carbon nanotube wires in the carbon nanotube
cable can be twisted or untwisted. In an untwisted carbon nanotube
cable, the carbon nanotube wires are substantially parallel with
each other. In a twisted carbon nanotube cable, the carbon nanotube
wires are twisted with each other.
[0060] The carbon nanotube structure can be adhered to a supporter,
such as a frame or a substrate.
[0061] The nanoparticles 104 are spaced from each other and coated
on the surface of each of the carbon nantoubes of the carbon
nanotube structure 100. The distances between two adjacent
nanoparticles 104 are larger than the diameters of each
nanoparticle 104. The diameter of each of the nanoparticles 104 is
in a range from about 1 nm to about 100 nm. In one embodiment, the
diameter of the nanoparticle is in a range from about 1 nm to about
50 nm. Each nanoparticle 104 wraps part surface of at least one
carbon nanotube. When the size of the carbon nanotube is smaller
than that of the nanoparticle 104, the whole carbon nanotube is
totally wrapped by the nanoparticle 104. The carbon nanotubes also
can be bundled together to form a plurality of carbon nanotube
bundles. The nanoparticles 104 are spacedly coated on the surface
of the carbon nanotube bundle and arranged along the length
direction of the carbon nanotube bundle. The nanoparticles 104 and
the carbon nanotube are attracted by chemical bond and van Der
Waals attractive force. The carbon nanotube composite material 10
has a large specific surface because the carbon nanotubes have gaps
therebetween and the nanoparticles 104 are spacedly arranged among
the carbon nantoubes of the carbon nanotube structure. The carbon
nanotubes are isotropic, long, curved, disordered, and entangled
with each other.
[0062] The nanoparticles 104 can be metal nanoparticles, non-metal
nanoparticles, alloy nanoparticles, metallic oxide nanoparticles,
polymer nanoparticles, and any combination thereof. The metallic
oxide nanoparticles include titanium dioxide (TiO.sub.2), zinc
oxide (ZnO), nickel oxide (NiO), aluminum oxide (AlO), and any
combination thereof. In one embodiment, the nanoparticle 104 is
TiO.sub.2. The shape of the nanoparticles 104 can be a sphere, a
spheroid, and any combination thereof. In one embodiment, the
carbon nanotube structure 100 includes a plurality of the carbon
nanotube wires. The carbon nanotube wires can be substantially
parallel to each other, or have a discernable angle between the two
adjacent carbon nanotube wires to form a carbon nanotube film. At
least one carbon nanotube of the carbon nanotube wire is embedded
in one nanoparticle 104. In one embodiment, the diameters of the
nanoparticles 104 are in a range from about 80 nm to about 120
nm.
[0063] The carbon nanotube composite material 10 in the present
embodiment has many advantages. Firstly, the carbon nanotube
composite material 10 has a large specific surface because the
carbon nanotubes have gaps therebetween and the nanoparticles 104
are spaced among the carbon nantoubes of the carbon nanotube
structure. The carbon nanotube composite material 10 which has a
lager specific surface can be used as a good catalyst. Secondly,
the nanoparticles 104 are uniformly distributed on the carbon
nanotube structure 100 to prevent the nanoparticles 104 from
agglomerating. In addition, the carbon nanotube composite material
10 is a free-standing structure because the carbon nanotube
structure 100 is a free-standing structure.
[0064] Method for Carbon Nanotube Composite Material
[0065] Referring to FIGS. 9 and 10, one embodiment of a method for
making the carbon nanotube composite material 10 includes:
[0066] (1) providing a free-standing carbon nanotube structure
100;
[0067] (2) introducing at least two types of reacting materials
into the carbon nanotube structure; and
[0068] (3) activating the reacting materials to grow a nanowire
structure.
[0069] Method For Step 1
[0070] In step (1), the carbon nanotube structure 100 includes a
plurality of carbon nanotubes adhered to each other by the van Der
Waals attractive force to form a free-standing structure. The
carbon nanotube structure 100 includes one or more carbon nanotube
films or one or more carbon nanotube wires. The carbon nanotube
film structure can be a grown carbon nanotube film, a flocculated
carbon nanotube film, a pressed carbon nanotube film, or a drawn
carbon nanotube film.
[0071] The carbon nanotube films can be adhered to a frame or on a
substrate directly. In one embodiment, two carbon nanotube films
can be stacked side by side substantially parallel to each other on
a metal frame to form the carbon nanotube structure 100.
[0072] Method For Step 2
[0073] In step (2), the reacting materials can be solid, liquid, or
gaseous.
[0074] One method for introducing the at least two types of
reacting materials into the carbon nanotube structure includes
(2a1) introducing a first reacting material to form a first
reacting material layer on the surface of the carbon nanotube
structure, and (2a2) introducing a second reacting material to the
carbon nanotube structure.
[0075] In step (2a1), the thickness of the first reacting material
layer is about 1 nm to about 100 nm. The material of the first
reacting material is dependent on the material of the nanoparticle
104 to be prepared. The first reacting material can be a metal,
non-metal, semiconductor, and any combination thereof as desired.
In one embodiment, the first reacting material is metal, for
example, titanium (Ti), aluminum (Al), or nickel (Ni), and metal
compound nanoparticles, for example, metal oxide or metal
silicides. The nanoparticle 104 structure can be obtained by
introducing the first reacting material. In one embodiment, the
first reacting material is silicon and a non-metal compound, for
example, silicon nitride or silicon carbide nanostructure can be
obtained by introducing the first reacting material.
[0076] The method for forming the first reacting layer can be
chemical vapor deposition (CVD), physical vapor deposition (PVD),
impregnation method, spraying method, or silk-screen printing
method. The metal or metal oxide can be sputtered on the surface of
the carbon nanotube structure by the PVD method. The non-metallic
nitride or carbide can be formed on the surface of the carbon
nanotube structure by the CVD method. The metal organic solution
can be formed on the surface of the carbon nanotube structure by
the methods of impregnation, spraying, or silk-screen printing.
Part or all the surface of the carbon nanotube structure can be
coated with the first reacting materials.
[0077] In step (2a2), the second reacting material can be liquid or
gaseous. The gaseous second reacting material can be oxygen gas,
nitrogen gas, silicon source gas and carbon source gas, and any
combination thereof. The method of introducing the gaseous second
reacting material is directly introducing the gaseous second
reacting material into a chamber having a carbon nanotube structure
deposited thereon. The gaseous second reacting material is
distributed on the surroundings of the carbon nanotube structure
and the first reacting material.
[0078] The second reacting material can also be in liquid form such
as methanol, ethanol, acetone, liquid resin, and any combination
thereof. The method of introducing the liquid second reacting
material is by directly dropping the liquid second reacting
material on the surface of the carbon nanotube structure or
immersing the carbon nanotube structure in the liquid reacting
material. The liquid second reacting material is distributed on the
surroundings of the carbon nanotube structure and the first
reacting material.
[0079] Another method for introducing the at least two types of
reacting materials into the carbon nanotube structure includes
(2b1) forming a first reacting material layer on the surface of the
carbon nanotube structure and (2b2) forming a second reacting
material layer on the surface of the first reacting material layer.
The total thickness of the first and the second reacting material
layers is about 1 nm to about 100 nm. In one embodiment, the first
reacting material layer is a metal layer, for example, an Al and Ti
layer, and the second reacting material layer is a silicon layer.
In one embodiment, the first and the second reacting layer are
metal layers, for example, an Al and Ti layer or an Al and Ni
layer.
[0080] Yet another method for introducing the at least two types
reacting materials into the carbon nanotube structure includes
simultaneously introducing two gaseous reacting materials, two
liquid reacting materials, or a combination of one gaseous reacting
material and one liquid reacting material.
[0081] In one embodiment, a Ti layer is deposited on the surface of
the carbon nanotube structure by a magnetron sputtering method. The
carbon nanotube structure with the Ti layer is exposed to the
atmosphere, thus creating a sufficient contact between the Ti
particles on the surface of the carbon nanotube structure and the
oxygen gas in the atmosphere. When the thickness of the Ti layer
reaches about 1 nm to about 100 nm, a plurality of successive
titanium dioxide (TiO.sub.2) nanoparticles is formed after the
reaction of the Ti layer and the oxygen gas. When the thickness of
the Ti layer is less than 100 nm, a plurality of spaced TiO.sub.2
particles can be formed.
[0082] Method For Step 3
[0083] In step (3), the reacting materials are activated to grow
nanoparticles. The methods of activating the reaction materials can
be by heating, laser scanning, reactive sputtering and any
combination thereof. The gas containing a silicon source and a
carbon source is activated to grow silicon carbide nanoparticles by
the heating method. The metal and oxygen gas are activated to grow
metallic oxide nanoparticles by the laser irradiating method.
Vacuum sputtering of metal particles and oxygen gas grows metal
oxide nanoparticles.
[0084] In one embodiment, the laser scanning is used to render the
reacting materials to react. When the total surface of the carbon
nanotube structure is scanned via the laser scanning method, the
reacting materials on the surface of the carbon nanotube structure
can be reacted. When a part of the surface of the carbon nanotube
structure is scanned via the laser scanning method, the reacting
materials on the surface of the carbon nanotube structure diffuse
along the arrangement of the carbon nanotubes from the position
where the laser is scanned.
[0085] When the part of the surface of the carbon nanotube
structure is scanned, the carbon nanotube structure can be arranged
on a substrate. The larger the heat transfer coefficient, the
faster the heat transfer toward the substrate and the slower the
growth speed of the carbon nanotube structure. If the carbon
nanotube structure is suspended on the frame, the carbon nanotube
structure has the fastest heat transfer because of a small
coefficient of the air.
[0086] Nanoparticles 104 are coated on the surface of the carbon
nanotube structure and grow along the length direction of the
carbon nanotubes of the carbon nanotube structure. The carbon
nanotube composite material 10 is free-standing because the carbon
nanotube structure utilized as the template is free-standing.
[0087] Referring to FIGS. 11 to 13, the carbon nanotube composite
material 10 have three different sizes of TiO.sub.2 nanoparticles
formed by activating three different thicknesses, 10 nm, 20 nm, 50
nm of the reacting material layer. The carbon nanotube composite
material 10 includes a carbon nanotube structure 100 and a
plurality of uniformly distributed TiO.sub.2 nanoparticles. The
size distribution of the TiO.sub.2 nanoparticles diameter change
with the Ti layer thickness. If the layer thickness is sufficiently
small, the size of the nanoparticles diameter are more uniformly
distributed. Referring to FIG. 14, a TEM image of the carbon
nanotube composite material 10 of FIG. 11, a plurality of carbon
nanotubes are embedded in one TiO.sub.2 nanoparticle.
[0088] The method of introducing reacting materials into the carbon
nanotube structure 100 and activating the reacting materials to
grow the carbon nanotube composite material 10 is thus easy, low
cost, and is suitable for mass production.
[0089] Finally, it is to be understood that the embodiments
described are intended to illustrate rather than limit the present
disclosure. Variations may be made to the embodiments without
departing from the spirit of the present disclosure as claimed. The
embodiments illustrate the scope of the present disclosure but do
not restrict the scope of the invention.
* * * * *