Nonadiabatic chemical-to-electrical energy conversion in heterojunction nanostructures

Abstract

Nonadiabatic energy dissipation by electron subsystem of nanostructured solids unveil interesting opportunities for the solid-state energy conversion and sensor applications. We found that planar Pt/GaP and Pd/GaP Schottky structures with nanometer thickness metallization demonstrates a nonadiabatic channel for the conversion into electricity the energy of a catalytic hydrogen-to-water oxidation process on the metal layer surface. The observed above thermal current greatly complements the usual thermionic emission current and its magnitude is linearly proportional to the rate of formation and desorption of product water molecules from the nanostructure surface. The possibilities of utilizing the nonadiabatic functionality in chemical-to-electrical energy conversion devices are discussed.

Thermal desorption spectroscopy from the surfaces of metal-oxide-semiconductor nanostructures

“…These allow the direct detection and quantification of hot charge carriers created in the top metal nanofilm in the course of a catalysed chemical reaction, e.g., the recombination of atomic hydrogen 1,8,9 or the oxidation of carbon monoxide 2, 10 and hydrogen. 3,4,11 Comparison of the amount of detected hot charge carriers to the number of chemical events on the surface of the chemi-electrical devices can in principle provide an answer to the long-standing question regarding the role of transient electronic excitations of the substrate in the pathways of energy dissipation; 12-14 a question, the answer to which is fundamental for the development of a predictive theory of surface chemistry on a molecular level.…”

Non-adiabatic processes in the charge transfer reaction of O2 molecules with potassium surfaces without dissociation

“…22,23 Reaction induced currents have also been reported during catalytic reactions on thin film Schottky diodes. [24][25][26] These experiments were performed at elevated temperatures and higher pressures so that thermoelectric effects became relevant and competed with the chemicurrent generation. 27,28 Electronic excitations are explicitly applied in photochemistry to promote and initiate surface reactions.…”

Separation of hot electron current component induced by hydrogen oxidation on resistively heated Pt/n-GaP Schottky nanostructures

“…1. [4][5][6][7] For such a configuration, the inplane currents are shunted with the electrically continuous nanofilm and with the Ohmic contact metallization fabricated on the entire reverse side of the semiconducting substrate. A low-resistance Ohmic contact is also fabricated on the reverse side of the substrate.…”

“…A low-resistance Ohmic contact is also fabricated on the reverse side of the substrate. 4,5,7,14,20 Therefore, the nonadiabatic chemicurrent in Schottky nanostructure may be accompanied with an out-of-plane thermal current of thermoelectric origin induced by the external heating. These electrons reach the semiconductor anode area, where they relax, drift to the external circuit via the Ohmic contact, and return to the nanofilm cathode.…”