Pre-equilibrium chemical reaction energy converter

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PRE-EQUILIBRIUM CHEMICAL REACTION the appropriate charge carrier (e.g., hole or electron). The ENERGY CONVERTER diodes are placed in contact with or near the catalyst nanolayer or nanocluster within a distance whose order of

CROSS-REFERENCE TO RELATED magnitude is less than approximately the mean free path of APPLICATIONS the appropriate ballistic charge carrier originating in the This is a division of application Ser. No. 09/304,979, filed catalyst.

the

In one embodiment, the diode is located adjacent to catalyst cluster, while in a further embodiment, the diode

May 4, 1999 now U.S. Pat. No. 6,114,620. is located under the catalyst, as a Substrate. FIELD OF THE INVENTION The charge carriers travel ballistically over distances that can exceed the width of appropriately fabricated Semicon

The present invention relates to the extraction of electrical ductor junctions, Similar to a thermionic effect. However, or mechanical energy or coherent radiation from chemical unlike the thermionic effect, the charge carriers in the case reactions occurring on the Surface of a catalyst before of the present invention need not have energy greater than thermal equilibrium has been reached by the forms of the the work function of the material involved. The charge released energy. 15 carrier motion is trapped as a difference in fermi level, or

BACKGROUND INFORMATION

chemical potential, between either Side of the junction. The resulting Voltage difference is indistinguishable from that of

Recent experimental observations have revealed clues to a photovoltaic collector. However, the charge carrier forces various catalytic processes occurring: 1) during the 0.01 itself into the Valence or conduction band and the circuit pico-Second time interval during which chemical reactants provides a counterpart hole or electron. form bonds with the Surface of a catalyst, causing the The present invention also provides devices and methods emission of charge carriers, Such as electrons and holes; 2) for converting the energy generated by catalytic reactions to during the picoSecond time interval during which reactants mechanical motion before the energy thermalizes. In an adsorb and lose energy in quantum Steps after becoming exemplary embodiment, the converted motion is used to trapped at a potential well between an adsorbate and a 25 move a hydraulic fluid against a resisting pressure. catalyst Surface, producing electronic friction, charge carrier Recent advances in the art of quantum wells, atomically currents and phonon emission; and 3) during the nanoSecond Smooth Superlattices and nanometer Scale fabrication permit and longer time intervals during which reaction intermedi a degree of tailoring of the physical parameters to favor a ates and products radiate electromagnetic energy, either particular reaction pathway (charge carrier, phonon, photon) while trapped on a catalyst Surface or immediately after or to enhance the efficiency of the energy collector. escaping it. These processes entail three energy releasing The temperature of operation of a device in accordance processes, namely: 1) charge carrier emission (electrons and with the present invention can be as low as hundreds of holes), 2) phonon emission and 3) photon emission. degrees Kelvin, which is much lower than the typical The discovery of these pre-equilibrium emissions pro 35 operational temperatures of conventional thermophotovol vides new pathways to convert the high grade chemical taics and thermionic systems (1500 to 2500 Kelvin). energy available during pre-equilibrium phases into useful Moreover, the power per mass and power per Volume work. The term “pre-equilibrium” refers to the period, ultimately achievable using pre-equilibrium emissions in however brief, during which the products of reactions have accordance with the present invention exceeds that of fuel not yet come to thermal equilibrium. These products include 40 cells, conventional thermo-photovoltaics, and conventional energy emissions, Such as charge carriers, high frequency thermionic Systems.

phonons normally associated with the optical branch lattice Furthermore, in comparison to fuel cells which require vibrations and with acoustic branch vibrations of similar wavelength and energy; and excited State chemical product mixing ofducting, complex fuel and the devices of the present invention allow air in the same duct, thereby simplifying

Species. 45 ducting requirements.

Prior to the discovery of these rapid energy emission The combination of high Volume and mass power density, pathways, the energies resulting from a catalytic process, Simplicity, and lower temperature operation makes the meth Such as the heat of adsorption and the heat of formation, ods and devices were considered to be heat associated with an equilibrium uniquely useful. of the present invention competitive and condition. Indeed, after tens of femtoseconds, emitted 50 charge carriers have thermalized and after a few to hundreds BRIEF DESCRIPTION OF THE DRAWING of picoSeconds, emitted phonons have thermalized.

FIG. 1. Shows a cross-section of an exemplary embodi

SUMMARY OF THE INVENTION ment of a device for generating electricity in accordance In an exemplary embodiment of the present invention, the 55 with the present invention.

emissions of charge carriers, Such as electron-hole pairs, ment FIG. 2 shows a cross-section of an exemplary embodi generated by chemical activity and reactions on or within of a device for converting the energy released by a catalyst Surfaces, clusters or nanoclusters, are converted into catalytic reaction into mechanical work. electric potential. In an exemplary embodiment, Semicon FIG. 3 shows a cross-section of an exemplary embodi ductor diodes Such as p-n junctions and Schottky diodes 60 ment of a device for generating electricity piezoelectrically. formed between the catalyst and the Semiconductors are FIG. 4 shows an exemplary embodiment of an arrange used to carry out the conversion. The diodes are designed to ment for generating electricity or radiation beams in accor collect ballistic charge carriers and can be Schottky diodes, dance with the present invention. pn junction diodes or diodes formed by various combina DETAILED DESCRIPTION tions of metal-Semiconductor-oxide Structures. The inter 65 layer oxide thickneSS is preferably less than the particular FIG. 1 shows a cross-sectional view of an exemplary ballistic mean free path asSociated with the energy loss of embodiment of a device in accordance with the present

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invention. The device of FIG. 1, includes a catalyst 105 output leads for the substrate diode. Contacts 101 and 112 which is arranged on a top Surface of the device to come into are the electrical output leads for the Surface diode. contact with oxidizer molecules 103 and fuel molecules 102. In the device of FIG. 1, the catalyst layer 105 may In the exemplary embodiment of FIG. 1, the catalyst 105 can comprise a quantum well Structure (including quantum dots) be comprised of platinum or palladium, the oxidizer 103 can having a thickness typically less than 20 nm and being be comprised of air and the fuel 102 can be comprised of Sufficiently Small So as to alter the density of electron States hydrogen or a reactant hydrocarbon Such as methanol or in the catalyst to favor the production of Substantially ethanol. Exhaust molecules 104 result from the catalyzed monoenergetic holes or electrons. The Substrate diode 109 reaction.

The exemplary device of FIG. 1 comprises a pair of of and the catalyst 105 may be separated by an interlayer 106 metal that permits matching the lattice parameters of the

Schottky diodes which act as charge carrier collectors, with catalyst one diode 113 being arranged on the top Surface of the to this interlayer. The catalyst 105 and interlayer 106 device, adjacent to the catalyst 105 (the “adjacent surface comprise the quantum well. The interlayer 106 must be diode') and the other diode 109 being arranged in the tron transportthinintoSothe

Sufficiently as to permit non-energy changing elec diode. The thickness of the interlayer substrate 108, below the catalyst (the “substrate diode”). An 15 106 should be preferably less than 20 nanometers. insulating layer 111 is arranged between the adjacent Surface diode 113 and the substrate 108, as shown. The diodes 109 In an exemplary embodiment of a device in accordance and 113 preferably comprise a bipolar Semiconductor mate with the present invention, the substrate diode 109 com rial Such as InGaASSb with a composition chosen to opti prises an n-type direct band gap Semiconductor with a band mize the chosen operating conditions. For example, the gap chosen to favor the emission of energetic electrons. Second harmonic of a CO Stretch vibration on a catalyst In a further exemplary embodiment, the thickness or Surface at 2340 per cm energies gives a photon energy of cluster size (if arranged in clusters) of the catalyst layer 105 0.58 eV. (This matches the 0.53 eV band gap of a recently is Sufficiently Small So as to permit the appearance of band developed InCaAsSb diode described in G. W. Charache et gaps, discrete electron States and catalyst properties unlike al., “InGaAsSb thermophotovoltaic diode: Physics 25 the same material in bulk. In this case, the catalyst 105 can evaluation,” Journal of Applied Physics, Vol. 85, No. 4, be comprised, preferably, of gold, Silver, copper, or nickel Febuary 1999). The diodes 109 and 113 preferably have and be arranged as monolayer, 200 atom clusters. relatively low barrier heights, such as 0.05 to 0.4 volts. FIG. 2 shows an exemplary embodiment of a device in The Substrate diode 109 should be forward biased Suffi accordance with the present invention in which the emis ciently (e.g., up to 3 volts) to raise its conduction and Sions of phonons generated by adsorbing and bonding valence bands above the fermi level of the catalyst 105 so as reactions on or within catalyst Surfaces, clusters or nano to match the energy levels of the adsorbed reactants on the Structures are converted into hydraulic fluid pressure. catalyst Surface, Such as oxygen or hydrocarbon free radi In accordance with the present invention, pressures gen cals. This induces resonant tunneling of energy into the erated by phonons directed into a catalyst body on a first Side substrate diode 109 by photons. The dimension of the oxide 35 of the catalyst body form a phonon wave which can be barrier or the depletion region should be kept to less than the guided by the geometry of the catalyst (or Substrate upon ballistic transport dimension, which is on the order of 10 which the catalyst may be situated) So that the phonons nanometerS. travel to the other Side of the Substrate and impart a preSSure A metal such as Mg, Sb, Al, Ag, Sn Cu or Ni may be used onto a fluid. The thickness of this travel should be less than to form an interlayer 106 between the catalyst 105 and the 40 the mean distance over which the direction of the phonon semiconductor of the substrate diode 109. The interlayer 106 remains Substantially unperturbed. The phonons arrive at an Serves to provide a lattice parameter match between the angle (a "grazing” angle) Such that the directional and catalyst material and the Substrate, which in turn provides a asymmetric pressure of the arriving phonons appears as Smooth and planar interface Surface with which to construct wave motion on the other side of the catalyst body which a quantum well Structure consisting of the catalyst, the 45 pushes against a fluid Such as a liquid metal or Sacrificial Vacuum above and the interlayer below. A quantum well interface, causing it to move in a direction parallel to the Structure with Smooth interfaces alters the density of elec bottom Surface. An apparent negative coefficient of friction tron States in the directions toward the Substrate and toward between the wall and the fluid is exhibited due to the wave the vacuum, So as to enhance the number of electrons with motion or directed impulses along the Surface of the bottom the desired energy. The thickness of the catalyst and the 50 of the device.

interlayer should be Small enough to permit ballistic trans The exemplary device comprises a substrate 202 with top port of charge carriers. This dimension is typically less than and bottom Surfaces having a Saw-tooth pattern, as shown in 20 nanometers. Quantum well Structures with thickneSS leSS the cross-sectional view of FIG. 2. The bottom Surface is in than 0.5 nanometer are possible in the present State of the art. contact with a hydraulic fluid 204. As shown in FIG. 2, the The quantum well Structure may be constructed as an island, 55 Substrate can be thought of as comprising a plurality of like a pancake on a Surface (also referred to as a "quantum Sub-structures 200 having rectangular cross-sections and dot”). arranged adjacent to each other at an angle with respect to The device of FIG. 1 may also include a non-conducting the hydraulic fluid 204.

layer 107 arranged between the substrate diode 109 and the At the top surface of the substrate, each sub-structure 200 catalyst 105. The layer 107, which can be comprised of an 60 includes a layer 201 comprising a catalyst. On an exposed oxide, permits forward-biasing of the diode 109 without a Side Surface between adjacent Sub-structures, each Sub significant increase in the forward current. The layer 107 structure 200 includes a layer 202 of material which is inert provides a barrier against Such forward current. An optional with respect to the catalyst and the reactants. The body of oxide 114 barrier may also be arranged on the Surface of the each sub-structure is comprised of a substrate 203, which device between the catalyst 105 and the surface diode 113. 65 also acts as a phonon waveguide. Platinum can be used for Electrical contacts 101, 110 and 112 are arranged as the catalyst layer 201 and for the Substrate 203 with air as the shown in FIG. 1. Contacts 101 and 110 serve as electrical oxidizer, ethanol or methanol as the hydrocarbon reactant

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S 6 fuel and water or mercury as the hydraulic fluid 204. The that converts photons into electricity, collects electrons as hydraulic fluid can also serve as a coolant for the device, electricity, and converts phonons into electricity. thereby permitting high power density operation. In the exemplary embodiment of FIG. 3, as the reactants The catalyst 201 and substrate 203 may be comprised of interact with the catalytic layer 301, phonons generated by the same material, e.g., platinum. Other Substrate materials the reactions are conducted into the piezoelectric material may be used based on Structural considerations, manufac 303. AS a result, a potential is induced in the piezoelectric turability and/or impedance matching So as to maximize the material 303 at the electrical contacts 302. propagation of the phonon motion into the hydraulic fluid. The geometry of the Substrate 303 is preferably such as to The thickness of the platinum catalyst layer 201 and focus phonons So as to enhance the nonlinearity of the Substrate 203 should be less than the energy-changing mean piezoelectric element 303. This results in self-rectification of free path of optical branch phonons or high frequency the high frequency phonons. In an exemplary embodiment, acoustic branch phonons, which is at least of order 10 the piezoelectric element 303 is preferably curved and nanometers and can be as large as one micron. shaped like a lens or concentrating reflector So as to focus Nanofabrication methods can be used to form the saw the phonons generated by the catalyst on to the piezoelectric tooth patterns on the surfaces of the Substrate 202, with the 15 material. The focusing of the phonons causes large ampli dimension of a unit of Such pattern being as large as 1 tude atomic motions at the focus. The atomic motions micron. induced by this focusing cause the piezoelectric material to By depositing the inert layerS 202 as shown, e.g., on the become nonlinear, causing non-linear responses Such as the right-facing facets of the Saw-tooth pattern of the top generation of electricity in the material at the focus. This in Surface, a preferential direction is thereby established for turn results in the piezo-material becoming a rectifier of the reactions and thus for phonon propagation, as indicated by phonon-induced high frequency current.

the arrow in FIG. 2. Acoustic, ultraSonic or gigahertz acoustic Rayleigh waves Acoustic, ultraSonic or gigahertz acoustic Rayleigh waves can be used on the catalyst Side of the exemplary device of on the catalyst Side can be used to Stimulate the reaction rate FIG. 3 to stimulate the reaction rate and synchronize the and Synchronize the emission of phonons. The waves 25 emission of phonons, to enhance the magnitude of the increase the magnitude of the phonon emission and cause phonon emission and to cause coherent emission, greatly coherent emission, greatly enhancing both the peak and enhancing both the peak and average power delivered to the average power. piezoelectric material 303. Acoustic Rayleigh waves accel In a further embodiment, a thin layer or layers of material erate oxidation reactions on platinum catalyst Surfaces. are arranged between the Substrate and the fluid. These Surface acoustic waves can be generated on the Surface of layers are comprised of materials having acoustic imped the catalyst 301 using a generator (not shown). Such waves ances between that of the substrate 202 and the hydraulic may have acoustic, ultrasonic or gigahertz frequencies. The fluid 204, So as to maximize the transmission of momentum Rayleigh waves induce reactions So as to Synchronize the into the hydraulic fluid and minimize reflections back into reactions, which in turn Synchronizes the emission of the Substrate 204. The material should be selected So that the 35 phonons. The result is a pulsing bunching of the reactions, bulk modulus and phonon propagation properties of the which enhances the power delivered to the piezoelectric material cause the phonons emerging from the Substrate to material 303.

be transmittied substantially into the fluid with minimal The frequency of operation of the device of FIG. 3 is reflection and energy loSS. preferably in the GHz range and lower so that rectification In a further embodiment of a device in accordance with 40 of the alternating currents produced by the piezoelectric the present invention, the emissions of phonons generated material 303 can be achieved with conventional means, Such by catalytic reactions are converted into electrical current by as with Semiconductor diodes.

piezo-electric effects within materials as the phonons impact In a further exemplary embodiment of the present the materials. An exemplary embodiment of Such a device is invention, electromagnetic radiation, Such as infrared pho shown in FIG. 3. 45 tons emitted by excited State products Such as highly vibra The exemplary device of FIG.3 comprises a catalyst layer tionally excited radicals and final product molecules, is 301 arranged on a piezo-electric element 303, which is in converted into electricity photovoltaically. Stimulated emis turn arranged on a Supporting Substrate 304. The catalyst Sion of radiation is used to extract the energy from the layer 301 can be implemented as a nanocluster, nanolayer or excited State products, Such as highly vibrationally excited quantum well. Electrical leads 302 are provided at opposite 50 radical and reaction product molecules both on the catalyst ends of the piezoelectric element 303 across which a poten Surface and desorbing from it. The extracted energy appears tial is developed, in accordance with the present invention. in the form of a coherent beam or a Super-radiant beam of In the exemplary embodiment of FIG. 3, the catalyst layer infra-red or optical energy. The frequencies of the radiation 301 comprises platinum, with air as the oxidizer and ethanol correspond to fundamental (vibration quantum number or methanol as the hydrocarbon reactant fuel. The piezo 55 change of 1) or overtones (vibration quantum number electric element 303 can comprise any piezomaterial, change 2 or greater) of the normal mode vibration frequen including Semiconductors that are not normally cies of the reactants. Several different frequencies may be piezoelectric, Such as InGaAsSb. The lattice mismatch extracted simultaneously in this invention. While the result between the Semiconductor and the platinum produces a ing coherent beam is useful in its own right, this high Strain, commonly called a deformation potential which 60 intensity beam can also be photovoltaically converted into induces piezoelectric properties in Semiconductors, or fer electricity. In accordance with the present invention, Such roelectric or piezoelectric materials with a high nonlinearity emissions are created by reactions on catalyst Surfaces, and such as (Ba, Sr)TiO3 thin films, AlxGa1-xAS/GaAs and are accelerated by the use of optical cavities. FIG. 4 shows strained layer InCaAS/GaAs (111) B quantum well p-i-n an exemplary embodiment of an electric generator for StructureS. 65 performing Such a conversion.

Where the piezoelectric element 303 is comprised of a The device of FIG. 4 comprises one or more substrates Semiconductor, the Semiconductor becomes a diode element 401 upon which a catalyst 402 is arranged in a plurality of

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islands, nanoclusters, quantum well clusters or quantum A photovoltaic converter 405 is placed outside the volume dots. The catalyst clusters are Sufficiently spaced apart (e.g., of the catalyst-substrate stack 401/402 anywhere visible to tens of nanometers or more) and the Substrate is made the emitted radiation. Such a placement allows cooling the Sufficiently thin (e.g., less than a centimeter total optical photovoltaic collector 405 using known methods. The elec thickness), So that IR absorbtion is mitigated at the frequen trical output leads 406 of the photovoltaic collector 405 can cies of Specie emission. The assembly of catalyst clusters on be coupled to an electrical energy Storage device 411 via a the substrates 401 is substantially transparent to the reaction diode 410. The output of the photovoltaic converter 405 is radiations. The catalyst 402 is preferably platinum or pal in pulses with the pulse rate typically being greater than one ladium. The device preferably comprises a plurality of megahertz. The electrical energy Storage device 411 may Substrates 401 Stacked So as to permit a volume of reactions. 1O comprise, for example, a capacitor, Super-capacitor or bat The catalyst-substrate stack 401/.402 is enclosed in an tery. Given the high frequency of the pulsed output, a optical cavity having a highly reflective element 403 and a capacitor used as the Storage device 411 can be quite less reflective element 404 arranged as shown in FIG. 4. The compact. The capacitor need only be large enough to collect optical cavity and the catalyst-substrate stack 401/402 are the energy of a Single pulse. The energy Stored in the preferably resonant to the reaction radiations or their over 15 capacitor can thus be millions of times less than the energy tones. The optical cavity can be used to Stimulate overtone delivered by the converter 405 in one second. radiation, i.e., multipole radiation where the change in The chemical reactants on the catalyst Surface permit quantum number is 2 or more, to increase the energy of the overtone transitions because they are part of a “ladder” of radiation. The optical cavity preferably has multiple transitions and Strongly polarized on the catalyst Surface, frequencies, as in a Fabrey-Perot cavity, that are tuned to which permits all the transitions to have non-Zero dipole overtones of the Specie frequencies. radiation transition matrix elements. Also, the reactants have A fuel 407, Such as hydrogen, ethanol or methanol and an no rotational Smearing associated with free molecules in a oxidizer 408, such as air, are introduced into the optical gas because they are attached to the Surface and can not cavity where they interact with the catalyst-Substrate Stack rotate. These features permit a near monochromatic over 401/.402. Lean mixtures of fuel can be used so as to 25 tone light amplification by Stimulated emission of radiation. minimize resonant transfer, exchange or decay of excited The electromagnetic energy radiated by the Stimulation of State vibrational energy to other Specie of the same chemical species, as in the embodiment of FIG. 4, can be formed into makeup in the exhaust Stream, during the time these Species high brightness, quasi-monochromatic, poly-chromatic are in the optical cavity and the photovoltaic converter 405 radiations or coherent beams.

collects the radiation and converts it into electricity. In each of the above described embodiments which A Stimulated emission initiator and Synchronizer device include photovoltaic Semiconductors, the catalyst is prefer 412 is used to initiate and Synchronize the emissions in the ably operated at a high Surface power density, e.g., in exceSS optical cavity. The device 412 can be a commonly available of 10 watts per Square centimeter or with a peak Surface Stimulated emission oscillator and can be coupled to the 35 power density of at least one watt per Square centimeter, to device of the present invention in known ways. The optical enhance the efficiency of the photovoltaic Semiconductors. cavity can be designed in a known way to create Stimulated What is claimed is:

emission of radiation. A photovoltaic cell is typically not 1. A method of generating electromagnetic energy com very efficient in converting long wavelength IR photons prising: forming species in highly excited States on a cata (1000 to 5000 per centimeter) characteristic of the catalytic 40 lyst; and Stimulating the Species to emit electromagnetic reactions. The high peak power output of the device 412 radiation.

remedies this situation and makes the IR photovoltaic cell more efficient.