U.S. patent application number 09/808390 was filed with the patent office on 2001-09-06 for pre-equilibrium chemical reaction energy converter.
Invention is credited to Gidwani, Jawahar M., Zuppero, Anthony C..
Application Number | 20010018923 09/808390 |
Document ID | / |
Family ID | 23178778 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010018923 |
Kind Code |
A1 |
Zuppero, Anthony C. ; et
al. |
September 6, 2001 |
Pre-equilibrium chemical reaction energy converter
Abstract
The use of newly discovered chemical reaction products, created
when reactants combine to form products on the surface of a
catalyst, to generate electricity, beams of radiation or mechanical
motion. The invention also provides methods to convert the products
into electricity or motion. The electric generator consists of a
catalyst nanocluster, nanolayer or quantum well placed on a
substrate consisting of a semiconductor diode, and a semiconductor
diode on the surface of the substrate near the catalyst. The device
to generate mechanical motion consists of a catalyst nanocluster,
nanolayer or quantum well placed on a substrate, and a hydraulic
fluid in contact with the non-reaction side of the substrate, with
the surfaces of both the catalyst and substrate mechanically formed
to enhance the unidirectional forces on the fluid. Both devices use
a fuel-oxidizer mixture brought in contact with the catalyst. The
apparatus converts a substantial fraction of the reaction product
energy into useful work during the brief interval before such
products equilibrate with their surroundings.
Inventors: |
Zuppero, Anthony C.; (Idaho
Falls, ID) ; Gidwani, Jawahar M.; (San Francisco,
CA) |
Correspondence
Address: |
BAKER & MCKENZIE
805 THIRD AVENUE
NEW YORK
NY
10022
US
|
Family ID: |
23178778 |
Appl. No.: |
09/808390 |
Filed: |
March 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09808390 |
Mar 14, 2001 |
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09589553 |
Jun 7, 2000 |
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09589553 |
Jun 7, 2000 |
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09304979 |
May 4, 1999 |
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6114620 |
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Current U.S.
Class: |
136/248 ;
136/247; 136/253; 257/E29.166; 429/111 |
Current CPC
Class: |
H02N 11/002 20130101;
H02S 99/00 20130101; H02N 2/18 20130101; Y02E 10/50 20130101; H01L
29/66 20130101; Y10S 136/291 20130101 |
Class at
Publication: |
136/248 ;
136/247; 136/253; 429/111 |
International
Class: |
H01M 006/30; H02N
006/00; H01L 025/00; H01L 031/00 |
Claims
What is claimed is:
1. A method of moving an object, comprising: providing a catalyst
on a substrate; placing reactants in contact with the catalyst, the
reactants interacting with the catalyst and generating phonons,
wherein the phonons propagate into the substrate away from the
catalyst; and directing the phonons towards the object.
2. The method of claim 1, wherein the catalyst is arranged in a
plurality of clusters.
3. The method of claim 1, wherein the object is a fluid in contact
with a surface of the substrate.
4. A method of generating electricity comprising: forming species
in highly excited states on a catalyst thereby radiating
electromagnetic energy; and converting the electromagnetic energy
into electricity with a photovoltaic collector.
5. The method of claim 4, wherein the species includes at least one
of an excited state radical and an exhaust product.
6. The method of claim 4, comprising stimulating and accelerating a
reaction emission rate using an optical cavity.
7. The method of claim 4, comprising stimulating an overtone
radiation using an optical cavity.
8. The method of claim 7, wherein the overtone radiation includes
multipole radiation with a change in quantum number of two or
more.
9. The method of claim 4, wherein the catalyst operates at a peak
surface power density greater than one watt per square
centimeter.
10. A method of generating electromagnetic energy comprising:
forming species in highly excited states on a catalyst; and
stimulating the species to emit electromagnetic radiation.
11. A device for generating electricity, comprising: a catalyst,
and a substrate, wherein the catalyst is arranged on the substrate
and the substrate includes a substrate diode to receive charge
carriers from the catalyst, wherein upon introducing a fuel and an
oxidizer in contact with the catalyst, charge carriers are emitted
by the catalyst and an electrical potential is developed across the
substrate diode.
12. The device of claim 11 comprising a non-conducting layer
arranged between the substrate diode and the catalyst, wherein the
non-conducting layer permits control over a forward-bias and
forward current characteristic of the substrate diode.
13. The device of claim 11 comprising a surface diode, the surface
diode being arranged on a reactant side of the catalyst to receive
and capture electrons.
14. The device of claim 11, wherein the substrate diode is forward
biased so as to raise its conduction and valence bands above a
fermi level of the catalyst so as to match energy levels of the
adsorbed species.
15. The device of claim 11, wherein the substrate diode comprises
an InGaAsSb semiconductor.
16. The device of claim 13, wherein the surface diode comprises an
InGaAsSb semiconductor.
17. The device of claim 11, wherein the fuel includes at least one
of ethanol, methanol and hydrogen.
18. The device of claim 11, wherein the substrate diode is a
Schottky diode having a band gap larger than an energy of reactions
on a surface of the catalyst.
19. The device of claim 13, wherein the surface diode is a Schottky
diode having a band gap larger than a bond energy or a reaction
energy.
20. The device of claim 11, wherein the substrate diode is a
Schottky diode having a barrier height in a range of 0.05 to 0.4
volts.
21. The device of claim 13, wherein the surface diode is a Schottky
diode having a barrier height in a range of 0.05 to 0.4 volts.
22. The device of claim 11, wherein the catalyst includes at least
one of platinum and palladium.
23. The device of claim 11, wherein the catalyst includes at least
one of a quantum well and a quantum dot having a thickness
sufficiently small so as to alter a density of electron states in
the catalyst to favor the production of substantially monoenergetic
holes or electrons.
24. The device of claim 11, comprising a layer of metal arranged
between the substrate diode and the catalyst, wherein the layer of
metal matches a catalyst lattice parameter and allows the metal and
catalyst layers to be formed as a quantum well.
25. The device of claim 12, wherein the catalyst has a thickness of
one nanometer or less.
26. The device of claim 11, wherein the substrate diode includes an
n-type direct band gap semiconductor having a band gap which favors
emission of energetic electrons.
27. The device of claim 11, wherein a dimension of the catalyst is
sufficiently small so as to have properties unlike the same
material in bulk.
28. The device of claim 11, wherein the catalyst includes at least
one of gold, silver, copper, and nickel.
29. The device of claim 11 comprising a coolant on a bottom surface
of the device.
30. The device of claim 11, wherein the catalyst operates at a peak
surface power density greater than one watt per square
centimeter.
31. A device for moving a fluid comprising: a catalyst, wherein
reactants impinging on a surface of the catalyst cause phonons to
be generated; a substrate, wherein the catalyst is arranged on a
top side of the substrate; and a hydraulic fluid, wherein the
hydraulic fluid is in contact with a bottom side of the substrate,
wherein the substrate acts as an acoustic waveguide for the
phonons, conveying the phonons to the bottom side of the substrate
so as to move the hydraulic fluid in a preferred direction.
32. The device of claim 31, wherein the top side of the substrate
has a cross section with a sawtooth pattern.
33. The device of claim 31, wherein the catalyst and an inert
material are arranged on portions of the top side of the substrate
so as to control the generation of phonons.
34. The device of claim 32, wherein the catalyst and an inert
material are arranged on alternating facets of the sawtooth
pattern.
35. The device of claim 31, wherein the bottom side of the
substrate has a cross section with a sawtooth pattern.
36. The device of claim 31, wherein a wave including at least one
of an acoustic, ultrasonic and a gigahertz acoustic Rayleigh wave
is applied to the catalyst to stimulate a reaction rate and
synchronize the phonon emission, thereby enhancing a magnitude of
the phonon emission and causing coherent emission.
37. The device of claim 31, comprising a layer of material arranged
between the substrate and the fluid, wherein the material causes
the phonons to be transmitted from the substrate substantially into
the fluid.
38. A device for generating electricity comprising: a catalyst; and
a substrate, wherein the catalyst is arranged on a surface of the
substrate and the substrate includes a piezoelectric element,
wherein phonons generated upon interaction of the catalyst with
reactants travel through the piezoelectric element which develops
an electrical potential as a result.
39. The device of claim 38, wherein the catalyst includes at least
one of a nanocluster, nanolayer and a quantum well.
40. The device of claim 38, wherein the piezoelectric element
includes a semiconductor having piezoelectric properties caused by
a lattice mismatch between the semiconductor and the catalyst.
41. The device of claim 38, wherein the substrate focuses phonons
so as to enhance a non-linear responses.
42. The device of claim 38, wherein a wave including at least one
of an acoustic, ultrasonic and a gigahertz acoustic Rayleigh wave
is applied to the catalyst to stimulate a reaction rate and
synchronize the phonon emission, thereby enhancing a magnitude of
the phonon emission and causing coherent emission.
43. A device for generating electricity comprising: a catalyst; a
substrate, wherein the catalyst is arranged on the substrate; and a
a photovoltaic converter, the photovoltaic converter being located
anywhere visible to radiation emitted by reactions involving the
catalyst.
44. The device of claim 43, wherein the catalyst includes at least
one of a nanocluster, a nanolayer and a quantum well.
45. The device of claim 43 comprising an optical cavity, wherein
the catalyst is located in the optical cavity and wherein the
optical cavity is tuned to a frequency of an excited state species
within the cavity.
46. The device of claim 43, wherein the optical cavity has multiple
frequencies that are tuned to overtones of the specie frequencies
and wherein the optical cavity stimulates overtone transitions.
47. The device of claim 46, wherein the optical cavity is a
Fabrey-Perot cavity.
48. The device of claim 45 comprising an optical oscillator for
stimulating emissions in the optical cavity.
49. The device of claim 43, wherein the catalyst includes at least
one of an island, nanocluster, quantum well cluster and a quantum
dot and the substrate includes a plurality of substrates arranged
in a stack, thereby forming a catalyst-substrate stack, wherein the
catalyst-substrate stack is tuned to at least one of a frequency or
overtone thereof of the radiation.
50. The device of claim 43, comprising cooling means for cooling
the photovoltaic converter.
51. The method of claim 4 comprising storing the electrical energy
in at least one of a capacitor, a super-capacitor and a
battery.
52. The device of claim 11 comprising an electrical storage device,
the electrical storage device being coupled to the substrate diode,
wherein the electrical storage device includes at least one of a
capacitor, a super-capacitor and a battery.
53. The device of claim 38 comprising: electrical contacts, the
electrical contacts being arranged on the piezoelectric element,
wherein the electrical potential appears at the electrical
contacts; and an electrical storage device, the electrical storage
device being coupled to the electrical contacts, wherein the
electrical storage device includes at least one of a capacitor, a
super-capacitor and a battery.
54. The device of claim 43 comprising an electrical storage device,
the electrical storage device being coupled to the photovoltaic
converter, wherein the electrical storage device includes at least
one of a capacitor, a super-capacitor and a battery.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the extraction of
electrical or mechanical energy or coherent radiation from chemical
reactions occurring on the surface of a catalyst before thermal
equilibrium has been reached by the forms of the released
energy.
BACKGROUND INFORMATION
[0002] Recent experimental observations have revealed clues to
various catalytic processes occurring: 1) during the 0.01
picosecond time interval during which chemical reactants form bonds
with the surface of a catalyst, causing the emission of charge
carriers, such as electrons and holes; 2) during the picosecond
time interval during which reactants adsorb and lose energy in
quantum steps after becoming trapped at a potential well between an
adsorbate and a catalyst surface, producing electronic friction,
charge carrier currents and phonon emission; and 3) during the
nanosecond and longer time intervals during which reaction
intermediates and products radiate electromagnetic energy, either
while trapped on a catalyst surface or immediately after escaping
it. These processes entail three energy releasing processes,
namely: 1) charge carrier emission (electrons and holes), 2) phonon
emission and 3) photon emission.
[0003] The discovery of these pre-equilibrium emissions provides
new pathways to convert the high grade chemical energy available
during pre-equilibrium phases into useful work. The term
"pre-equilibrium" refers to the period, however brief, during which
the products of reactions have not yet come to thermal equilibrium.
These products include energy emissions, such as charge carriers;
high frequency phonons normally associated with the optical branch
lattice vibrations and with acoustic branch vibrations of similar
wavelength and energy; and excited state chemical product
species.
[0004] Prior to the discovery of these rapid energy emission
pathways, the energies resulting from a catalytic process, such as
the heat of adsorption and the heat of formation, were considered
to be heat associated with an equilibrium condition. Indeed, after
tens of femtoseconds, emitted charge carriers have thermalized and
after a few to hundreds of picoseconds, emitted phonons have
thermalized.
SUMMARY OF THE INVENTION
[0005] In an exemplary embodiment of the present invention, the
emissions of charge carriers, such as electron-hole pairs,
generated by chemical activity and reactions on or within catalyst
surfaces, clusters or nanoclusters, are converted into electric
potential. In an exemplary embodiment, semiconductor diodes such as
p-n junctions and Schottky diodes formed between the catalyst and
the semiconductors are used to carry out the conversion. The diodes
are designed to collect ballistic charge carriers and can be
Schottky diodes, pn junction diodes or diodes formed by various
combinations of metal-semiconductor-oxide structures. The
interlayer oxide thickness is preferably less than the particular
ballistic mean free path associated with the energy loss of the
appropriate charge carrier (e.g., hole or electron). The diodes are
placed in contact with or near the catalyst nanolayer or
nanocluster within a distance whose order of magnitude is less than
approximately the mean free path of the appropriate ballistic
charge carrier originating in the catalyst. In one embodiment, the
diode is located adjacent to the catalyst cluster, while in a
further embodiment, the diode is located under the catalyst, as a
substrate.
[0006] The charge carriers travel ballistically over distances that
can exceed the width of appropriately fabricated semiconductor
junctions, similar to a thermionic effect. However, unlike the
thermionic effect, the charge carriers in the case of the present
invention need not have energy greater than the work function of
the material involved. The charge carrier motion is trapped as a
difference in fermi level, or chemical potential, between either
side of the junction. The resulting voltage difference is
indistinguishable from that of a photovoltaic collector. However,
the charge carrier forces itself into the valence or conduction
band and the circuit provides a counterpart hole or electron.
[0007] The present invention also provides devices and methods for
converting the energy generated by catalytic reactions to
mechanical motion before the energy thermalizes. In an exemplary
embodiment, the converted motion is used to move a hydraulic fluid
against a resisting pressure.
[0008] Recent advances in the art of quantum wells, atomically
smooth superlattices and nanometer scale fabrication permit a
degree of tailoring of the physical parameters to favor a
particular reaction pathway (charge carrier, phonon, photon) or to
enhance the efficiency of the energy collector.
[0009] The temperature of operation of a device in accordance with
the present invention can be as low as hundreds of degrees Kelvin,
which is much lower than the typical operational temperatures of
conventional thermophotovoltaics and thermionic systems (1500 to
2500 Kelvin). Moreover, the power per mass and power per volume
ultimately achievable using pre-equilibrium emissions in accordance
with the present invention exceeds that of fuel cells, conventional
thermo-photovoltaics, and conventional thermionic systems.
[0010] Furthermore, in comparison to fuel cells which require
complex ducting, the devices of the present invention allow mixing
of fuel and air in the same duct, thereby simplifying ducting
requirements.
[0011] The combination of high volume and mass power density,
simplicity, and lower temperature operation makes the methods and
devices of the present invention competitive and uniquely
useful.
BRIEF DESCRIPTION OF THE DRAWING
[0012] FIG. 1. shows a cross-section of an exemplary embodiment of
a device for generating electricity in accordance with the present
invention.
[0013] FIG. 2 shows a cross-section of an exemplary embodiment of a
device for converting the energy released by a catalytic reaction
into mechanical work.
[0014] FIG. 3 shows a cross-section of an exemplary embodiment of a
device for generating electricity piezoelectrically.
[0015] FIG. 4 shows an exemplary embodiment of an arrangement for
generating electricity or radiation beams in accordance with the
present invention.
DETAILED DESCRIPTION
[0016] FIG. 1 shows a cross-sectional view of an exemplary
embodiment of a device in accordance with the present invention.
The device of FIG. 1, includes a catalyst 105 which is arranged on
a top surface of the device to come into contact with oxidizer
molecules 103 and fuel molecules 102. In the exemplary embodiment
of FIG. 1, the catalyst 105 can be comprised of platinum or
palladium, the oxidizer 103 can be comprised of air and the fuel
102 can be comprised of hydrogen or a reactant hydrocarbon such as
methanol or ethanol. Exhaust molecules 104 result from the
catalyzed reaction.
[0017] The exemplary device of FIG. 1 comprises a pair of Schottky
diodes which act as charge carrier collectors, with one diode 113
being arranged on the top surface of the device, adjacent to the
catalyst 105 (the "adjacent surface diode") and the other diode 109
being arranged in the substrate 108, below the catalyst (the
"substrate diode"). An insulating layer 111 is arranged between the
adjacent surface diode 113 and the substrate 108, as shown. The
diodes 109 and 113 preferably comprise a bipolar semiconductor
material such as InGaAsSb with a composition chosen to optimize the
chosen operating conditions. For example, the second harmonic of a
CO stretch vibration on a catalyst surface at 2340 per cm energies
gives a photon energy of 0.58 eV. (This matches the 0.53 eV band
gap of a recently developed InGaAsSb diode described in G. W.
Charache et al., "InGaAsSb thermophotovoltaic diode: Physics
evaluation," Journal of Applied Physics, Vol. 85, No. 4, February
1999). The diodes 109 and 113 preferably have relatively low
barrier heights, such as 0.05 to 0.4 volts.
[0018] The substrate diode 109 should be forward biased
sufficiently (e.g., up to 3 volts) to raise its conduction and
valence bands above the fermi level of the catalyst 105 so as to
match the energy levels of the adsorbed reactants on the catalyst
surface, such as oxygen or hydrocarbon free radicals. This induces
resonant tunneling of energy into the substrate diode 109 by
photons. The dimension of the oxide barrier or the depletion region
should be kept to less than the ballistic transport dimension,
which is on the order of 10 nanometers.
[0019] A metal such as Mg, Sb, Al, Ag, Sn Cu or Ni may be used to
form an interlayer 106 between the catalyst 105 and the
semiconductor of the substrate diode 109. The interlayer 106 serves
to provide a lattice parameter match between the catalyst material
and the substrate, which in turn provides a smooth and planar
interface surface with which to construct a quantum well structure
consisting of the catalyst, the vacuum above and the interlayer
below. A quantum well structure with smooth interfaces alters the
density of electron states in the directions toward the substrate
and toward the vacuum, so as to enhance the number of electrons
with the desired energy. The thickness of the catalyst and the
interlayer should be small enough to permit ballistic transport of
charge carriers. This dimension is typically less than 20
nanometers. Quantum well structures with thickness less than 0.5
nanometer are possible in the present state of the art. The quantum
well structure may be constructed as an island, like a pancake on a
surface (also referred to as a "quantum dot").
[0020] The device of FIG. 1 may also include a non-conducting layer
107 arranged between the substrate diode 109 and the catalyst 105.
The layer 107, which can be comprised of an oxide, permits
forward-biasing of the diode 109 without a significant increase in
the forward current. The layer 107 provides a barrier against such
forward current. An optional oxide 114 barrier may also be arranged
on the surface of the device between the catalyst 105 and the
surface diode 113.
[0021] Electrical contacts 101, 110 and 112 are arranged as shown
in FIG. 1. Contacts 101 and 110 serve as electrical output leads
for the substrate diode. Contacts 101 and 112 are the electrical
output leads for the surface diode.
[0022] In the device of FIG. 1, the catalyst layer 105 may comprise
a quantum well structure (including quantum dots) having a
thickness typically less than 20 nm and being sufficiently small so
as to alter the density of electron states in the catalyst to favor
the production of substantially monoenergetic holes or electrons.
The substrate diode 109 and the catalyst 105 may be separated by an
interlayer 106 of metal that permits matching the lattice
parameters of the catalyst to this interlayer. The catalyst 105 and
interlayer 106 comprise the quantum well. The interlayer 106 must
be sufficiently thin so as to permit non-energy changing electron
transport into the diode. The thickness of the interlayer 106
should be preferably less than 20 nanometers.
[0023] In an exemplary embodiment of a device in accordance with
the present invention, the substrate diode 109 comprises an n-type
direct band gap semiconductor with a band gap chosen to favor the
emission of energetic electrons.
[0024] In a further exemplary embodiment, the thickness or cluster
size (if arranged in clusters) of the catalyst layer 105 is
sufficiently small so as to permit the appearance of band gaps,
discrete electron states and catalyst properties unlike the same
material in bulk. In this case, the catalyst 105 can be comprised,
preferably, of gold, silver, copper, or nickel and be arranged as
monolayer, 200 atom clusters.
[0025] FIG. 2 shows an exemplary embodiment of a device in
accordance with the present invention in which the emissions of
phonons generated by adsorbing and bonding reactions on or within
catalyst surfaces, clusters or nano-structures are converted into
hydraulic fluid pressure.
[0026] In accordance with the present invention, pressures
generated by phonons directed into a catalyst body on a first side
of the catalyst body form a phonon wave which can be guided by the
geometry of the catalyst (or substrate upon which the catalyst may
be situated) so that the phonons travel to the other side of the
substrate and impart a pressure onto a fluid. The thickness of this
travel should be less than the mean distance over which the
direction of the phonon remains substantially unperturbed. The
phonons arrive at an angle (a "grazing" angle) such that the
directional and asymmetric pressure of the arriving phonons appears
as wave motion on the other side of the catalyst body which pushes
against a fluid such as a liquid metal or sacrificial interface,
causing it to move in a direction parallel to the bottom surface.
An apparent negative coefficient of friction between the wall and
the fluid is exhibited due to the wave motion or directed impulses
along the surface of the bottom of the device.
[0027] The exemplary device comprises a substrate 202 with top and
bottom surfaces having a saw-tooth pattern, as shown in the
cross-sectional view of FIG. 2. The bottom surface is in contact
with a hydraulic fluid 204. As shown in FIG. 2, the substrate can
be thought of as comprising a plurality of sub-structures 200
having rectangular cross-sections and arranged adjacent to each
other at an angle with respect to the hydraulic fluid 204.
[0028] At the top surface of the substrate, each sub-structure 200
includes a layer 201 comprising a catalyst. On an exposed side
surface between adjacent sub-structures, each sub-structure 200
includes a layer 202 of material which is inert with respect to the
catalyst and the reactants. The body of each sub-structure is
comprised of a substrate 203, which also acts as a phonon
waveguide. Platinum can be used for the catalyst layer 201 and for
the substrate 203 with air as the oxidizer, ethanol or methanol as
the hydrocarbon reactant fuel and water or mercury as the hydraulic
fluid 204. The hydraulic fluid can also serve as a coolant for the
device, thereby permitting high power density operation.
[0029] The catalyst 201 and substrate 203 may be comprised of the
same material, e.g., platinum. Other substrate materials may be
used based on structural considerations, manufacturability and/or
impedance matching so as to maximize the propagation of the phonon
motion into the hydraulic fluid.
[0030] The thickness of the platinum catalyst layer 201 and
substrate 203 should be less than the energy-changing mean free
path of optical branch phonons or high frequency acoustic branch
phonons, which is at least of order 10 nanometers and can be as
large as one micron.
[0031] Nanofabrication methods can be used to form the sawtooth
patterns on the surfaces of the substrate 202, with the dimension
of a unit of such pattern being as large as 1 micron.
[0032] By depositing the inert layers 202 as shown, e.g., on the
right-facing facets of the saw-tooth pattern of the top surface, a
preferential direction is thereby established for reactions and
thus for phonon propagation, as indicated by the arrow in FIG.
2.
[0033] Acoustic, ultrasonic or gigahertz acoustic Rayleigh waves on
the catalyst side can be used to stimulate the reaction rate and
synchronize the emission of phonons. The waves increase the
magnitude of the phonon emission and cause coherent emission,
greatly enhancing both the peak and average power.
[0034] In a further embodiment, a thin layer or layers of material
are arranged between the substrate and the fluid. These layers are
comprised of materials having acoustic impedances between that of
the substrate 202 and the hydraulic fluid 204, so as to maximize
the transmission of momentum into the hydraulic fluid and minimize
reflections back into the substrate 204. The material should be
selected so that the bulk modulus and phonon propagation properties
of the material cause the phonons emerging from the substrate to be
transmittied substantially into the fluid with minimal reflection
and energy loss.
[0035] In a further embodiment of a device in accordance with the
present invention, the emissions of phonons generated by catalytic
reactions are converted into electrical current by piezo-electric
effects within materials as the phonons impact the materials. An
exemplary embodiment of such a device is shown in FIG. 3.
[0036] The exemplary device of FIG. 3 comprises a catalyst layer
301 arranged on a piezo-electric element 303, which is in turn
arranged on a supporting substrate 304. The catalyst layer 301 can
be implemented as a nanocluster, nanolayer or quantum well.
Electrical leads 302 are provided at opposite ends of the
piezoelectric element 303 across which a potential is developed, in
accordance with the present invention. In the exemplary embodiment
of FIG. 3, the catalyst layer 301 comprises platinum, with air as
the oxidizer and ethanol or methanol as the hydrocarbon reactant
fuel. The piezo-electric element 303 can comprise any
piezomaterial, including semiconductors that are not normally
piezoelectric, such as InGaAsSb. The lattice mismatch between the
semiconductor and the platinum produces a strain, commonly called a
deformation potential which induces piezoelectric properties in
semiconductors, or ferroelectric or piezoelectric materials with a
high nonlinearity such as (Ba, Sr)TiO3 thin films, AlxGa1-xAs/GaAs
and strained layer InGaAs/GaAs (111)B quantum well p-i-n
structures.
[0037] Where the piezoelectric element 303 is comprised of a
semiconductor, the semiconductor becomes a diode element that
converts photons into electricity, collects electrons as
electricity, and converts phonons into electricity.
[0038] In the exemplary embodiment of FIG. 3, as the reactants
interact with the catalytic layer 301, phonons generated by the
reactions are conducted into the piezoelectric material 303. As a
result, a potential is induced in the piezoelectric material 303 at
the electrical contacts 302.
[0039] The geometry of the substrate 303 is preferably such as to
focus phonons so as to enhance the nonlinearity of the
piezoelectric element 303. This results in self-rectification of
the high frequency phonons. In an exemplary embodiment, the
piezoelectric element 303 is preferably curved and shaped like a
lens or concentrating reflector so as to focus the phonons
generated by the catalyst on to the piezoelectric material. The
focusing of the phonons causes large amplitude atomic motions at
the focus. The atomic motions induced by this focusing cause the
piezoelectric material to become nonlinear, causing non-linear
responses such as the generation of electricity in the material at
the focus. This in turn results in the piezo-material becoming a
rectifier of the phonon-induced high frequency current.
[0040] Acoustic, ultrasonic or gigahertz acoustic Rayleigh waves
can be used on the catalyst side of the exemplary device of FIG. 3
to stimulate the reaction rate and synchronize the emission of
phonons, to enhance the magnitude of the phonon emission and to
cause coherent emission, greatly enhancing both the peak and
average power delivered to the piezoelectric material 303. Acoustic
Rayleigh waves accelerate oxidation reactions on platinum catalyst
surfaces. Surface acoustic waves can be generated on the surface of
the catalyst 301 using a generator (not shown). Such waves may have
acoustic, ultrasonic or gigahertz frequencies. The Rayleigh waves
induce reactions so as to synchronize the reactions, which in turn
synchronizes the emission of phonons. The result is a pulsing
bunching of the reactions, which enhances the power delivered to
the piezoelectric material 303.
[0041] The frequency of operation of the device of FIG. 3 is
preferably in the GHz range and lower so that rectification of the
alternating currents produced by the piezoelectric material 303 can
be achieved with conventional means, such as with semiconductor
diodes.
[0042] In a further exemplary embodiment of the present invention,
electromagnetic radiation, such as infrared photons emitted by
excited state products such as highly vibrationally excited
radicals and final product molecules, is converted into electricity
photovoltaically. Stimulated emission of radiation is used to
extract the energy from the excited state products, such as highly
vibrationally excited radical and reaction product molecules both
on the catalyst surface and desorbing from it. The extracted energy
appears in the form of a coherent beam or a super-radiant beam of
infra-red or optical energy. The frequencies of the radiation
correspond to fundamental (vibration quantum number change of 1) or
overtones (vibration quantum number change 2 or greater) of the
normal mode vibration frequencies of the reactants. Several
different frequencies may be extracted simultaneously in this
invention. While the resulting coherent beam is useful in its own
right, this high intensity beam can also be photovoltaically
converted into electricity. In accordance with the present
invention, such emissions are created by reactions on catalyst
surfaces, and are accelerated by the use of optical cavities. FIG.
4 shows an exemplary embodiment of an electric generator for
performing such a conversion.
[0043] The device of FIG. 4 comprises one or more substrates 401
upon which a catalyst 402 is arranged in a plurality of islands,
nanoclusters, quantum well clusters or quantum dots. The catalyst
clusters are sufficiently spaced apart (e.g., tens of nanometers or
more) and the substrate is made sufficiently thin (e.g., less than
a centimeter total optical thickness), so that IR absorbtion is
mitigated at the frequencies of specie emission. The assembly of
catalyst clusters on the substrates 401 is substantially
transparent to the reaction radiations. The catalyst 402 is
preferably platinum or palladium. The device preferably comprises a
plurality of substrates 401 stacked so as to permit a volume of
reactions.
[0044] The catalyst-substrate stack 401/402 is enclosed in an
optical cavity having a highly reflective element 403 and a less
reflective element 404 arranged as shown in FIG. 4. The optical
cavity and the catalyst-substrate stack 401/402 are preferably
resonant to the reaction radiations or their overtones. The optical
cavity can be used to stimulate overtone radiation, i.e., multipole
radiation where the change in quantum number is 2 or more, to
increase the energy of the radiation. The optical cavity preferably
has multiple frequencies, as in a Fabrey-Perot cavity, that are
tuned to overtones of the specie frequencies.
[0045] A fuel 407, such as hydrogen, ethanol or methanol and an
oxidizer 408, such as air, are introduced into the optical cavity
where they interact with the catalyst-substrate stack 401/402. Lean
mixtures of fuel can be used so as to minimize resonant transfer,
exchange or decay of excited state vibrational energy to other
specie of the same chemical makeup in the exhaust stream, during
the time these species are in the optical cavity and the
photovoltaic converter 405 collects the radiation and converts it
into electricity.
[0046] A stimulated emission initiator and synchronizer device 412
is used to initiate and synchronize the emissions in the optical
cavity. The device 412 can be a commonly available stimulated
emission oscillator and can be coupled to the device of the present
invention in known ways. The optical cavity can be designed in a
known way to create stimulated emission of radiation. A
photovoltaic cell is typically not very efficient in converting
long wavelength IR photons (1000 to 5000 per centimeter)
characteristic of the catalytic reactions. The high peak power
output of the device 412 remedies this situation and makes the IR
photovoltaic cell more efficient.
[0047] A photovoltaic converter 405 is placed outside the volume of
the catalyst-substrate stack 401/402 anywhere visible to the
emitted radiation. Such a placement allows cooling the photovoltaic
collector 405 using known methods. The electrical output leads 406
of the photovoltaic collector 405 can be coupled to an electrical
energy storage device 411 via a diode 410. The output of the
photovoltaic converter 405 is in pulses with the pulse rate
typically being greater than one megahertz. The electrical energy
storage device 411 may comprise, for example, a capacitor,
super-capacitor or battery. Given the high frequency of the pulsed
output, a capacitor used as the storage device 411 can be quite
compact. The capacitor need only be large enough to collect the
energy of a single pulse. The energy stored in the capacitor can
thus be millions of times less than the energy delivered by the
converter 405 in one second.
[0048] The chemical reactants on the catalyst surface permit
overtone transitions because they are part of a "ladder" of
transitions and strongly polarized on the catalyst surface, which
permits all the transitions to have non-zero dipole radiation
transition matrix elements. Also, the reactants have no rotational
smearing associated with free molecules in a gas because they are
attached to the surface and can not rotate. These features permit a
near monochromatic overtone light amplification by stimulated
emission of radiation.
[0049] The electromagnetic energy radiated by the stimulation of
species, as in the embodiment of FIG. 4, can be formed into high
brightness, quasi-monochromatic, poly-chromatic radiations or
coherent beams.
[0050] In each of the above described embodiments which include
photovoltaic semiconductors, the catalyst is preferably operated at
a high surface power density, e.g., in excess of 10 watts per
square centimeter or with a peak surface power density of at least
one watt per square centimeter, to enhance the efficiency of the
photovoltaic semiconductors.
* * * * *