Hot Electron Chemistry at Solid-Liquid Interfaces
Technical Report,15 Aug 2014,14 May 2018
UNIVERSITY OF WISCONSIN SYSTEM MADISON United States
Pagination or Media Count:
The facile generation of reactive species, including solvated electrons and hydrogen atoms, can enable local and sustainable industrial processes such as the production of ammonia and destruction of toxic waste. We have investigated the use of easily fabricated solid-state devices to generate these species electrochemically in water. We fabricated highly doped silicon coated with thin films of insulating silicon dioxide and the high k dielectric hafnium oxide, either bare or covered with gold. These devices rely on quantum mechanical tunneling of electrons from silicon through the insulating oxide directly into water. These electrons rapidly thermalize and become solvated. In addition, hydrogen atoms may be generated in the SiO2 layer, which then diffuse into solution. In both cases, reactive species are injected into the solvent itself and delivered to the companion reactant, bypassing reactions at the electrode surface. The chief competing reaction is hydrogen evolution, which must be minimized to achieve high selectivity. Our attempts to synthesize ammonia from water and dissolved nitrogen gas were unsuccessful because of overwhelming H2 production, but the decomposition of chloroethanol to ethanol radical and chloride anion in water shows promise as a means to destroy toxic waste.
- Nuclear Physics and Elementary Particle Physics