Photochemical splitting of CO2

INOR 355

Aaron Sathrum, asathrum@ucsd.edu, Department of Chemistry & Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358 and Clifford P. Kubiak, Department of Chemistry and Biochemistry, Univsersity of California - San Diego, 9500 Gilman Drive, Mail Code 0358, La Jolla, CA 92093-0358.
Photochemical "splitting" of carbon dioxide to carbon monoxide and oxygen both produces a fuel from solar energy and recycles atmospheric CO2. We will describe our recent studies of the photoelectrochemical reduction of CO2 using semiconducting p-GaP and p-Si and several reported electrocatalysts, as well as others recently developed in our laboratories for this purpose. Cyclic voltammetry is used to probe the photovoltage, photocurrent and electrocatalytic efficiencies developed by illuminated p-type semiconductor photocathodes. Interfacial kinetics are elucidated with model redox species such as methyl viologen and [Ru(bpy)3]2+, thereby establishing peak power, fill factor, and quantum efficiency. Carbon dioxide reduction is monitored using a gas chromatograph. Our efforts to prepare even more efficient two-electron CO2 reduction electrocatalysts will be described. A key challenge to realizing optimal performance from p-GaP lies in the preparation of good Ohmic contacts. Recent developments in the deposition of Zn and Zn alloy films on p-GaP will be described.