Electrochemical measurement on the photoelectrochemical reduction of aqueous carbon dioxide on p-Gallium phosphide and p-Gallium arsenide semiconductor electrodes

Abstract

The photoelectrochemical reduction of aqueous carbon dioxide was carried out using single crystal p-gallium phosphide and p-gallium arsenide as photocathodes. The organic products measured were mainly formic acid, but also formaldehyde and methanol. The effect of carbon dioxide pressure on the current-potential relationships and on yields of organic reduction products was studied using a photoelectrochemical autoclave, fitted with a quartz window. Highest Faradaic yield of reduction products, 80%, was obtained with a p-GaP cathode at a cathodic bias of -1.00 V (vs. a standard silver electrode), in a medium initially 0.5 M Na 2CO 3, under 8.5 atm pressure of CO 2, a cation exchange diaphragm and a platinum counterelectrode, under illumination with a 150 W Xe lamp.