Hermann NienhausProfessor, University of Duisburg-Essen, Germany
University of Illinois at Chicago
Department of Civil and Materials Engineering
October 15, 2010, Friday, Time 11am-12pm
Room 1047 ERF
Conversion of chemical energy into electricity in chemoelectronic devices
Faculty of Physics, University of Duisburg-Essen, Germany
Exothermic gas-metal surface interactions are essential in technically relevant processes such as heterogeneous catalysis, redox reactions and corrosion. Typically, a few eV per reaction event are dissipated and transferred into the degrees of freedom of the substrate. The transfer occurs either adiabatically by generating phonons/heat or non-adiabatically by direct excitation of electron-hole pairs in the metal. Heat as well as excited charge carriers can be converted into electric currents by use of solid-state electronic devices that can be applied in gas sensing, surface reaction monitoring and electrical power generation. The conversion of heat into electricity by use of thermoelectric devices is well-established. However, the existence of chemically induced hot charge carriers had been debated for many years until they were recently detected using the chemicurrent method . By use of thin metal film Schottky diodes the hot electrons and holes are converted into an electric chemicurrent before they decay within their extremely short lifetimes of typically 100 fs. After generation in the surface reaction the hot charge carriers are transported ballistically to the metal-semiconductor interface and traverse the Schottky barrier in case of sufficiently high excitation energies. The lecture gives an overview on the mechanisms and applications of the chemicurrent effect in Schottky diodes and discuss the principal differences to thermoelectric and electrochemical power generation.
 H. Nienhaus, Surf. Sci. Rep. 45 (2002) 3.