Photoelectrochemical reduction of carbon dioxide at p-type gallium arsenide and p-type indium phosphide electrodes in methanol

摘要

The photoelectrochemical reduction of carbon dioxide (CO_2)at p-type semiconductor electrodes,p-GaAs and p-InP,was studied in the methanol-based electrolyte.The main products from CO_2 were carbon monoxide and formic acid.The onset potentials of the photocathodic current in the methanol-based electrolyte were around - 1.2 and -0.8 V versus Ag/AgCl (saturated KC1)with p-GaAs and p-InP electrodes,respectively.Since the onset photopotentials were more positive compared to those with normal metallic electrodes,the photo-aided electrolysis can save electrical energy corresponding to a potential shift of 0.3-1.0 V to less negative potentials.The maximum current efficiency for CO (r_f = 41.5%)was obtained at -2.4 V for the p-InP photocathode.The current efficiencies for CO were better relative to those for formic acid at both p-GaAs and p-InP electrodes.The p-type indium phosphide electrode was found to be more effective than p-Si and p-GaAs for the photoelectrochemical reduction of CO_2 in methanol-based electrolyte.