Photoelectrochemical reduction of carbon dioxide. Final report

Photoelectrochemical reduction of CO2 to CO was carried out at p-type CdTe photoelectrode in N, N-dimethylformamide solutions containing 0.1M tetrabutyl ammonium perchlorate and 1-10% water. This is the first example of photoelectrochemical formation of CO using a semiconductor electrode without any catalyst on the electrode surface or a mediator in solution. The overpotential for CO2 reduction is decreased to 1.2V compared to the overpotential at metal electrodes (2.0V). It was observed that ammonium ion is a catalytic mediator for the CO2 reduction. The efficiency of CO2 reduction increases because H2 evolution is suppressed. Coating the electrodes with polymers such as polyaniline decreases the overpotential. FTIR study of the adsorbed species during the photoassisted reduction of CO2 at various bias potentials strongly suggest that CO2 reduction involves adsorption and formation of anion radical of CO2 on the surface of p-type CdTe.