Photoelectrocatalytic reduction of CO2 in LiOH/methanol at metal-modified p-InP electrodes

The photoelectrochemical reduction of CO2 at metal-modified p-InP photoelectrodes was investigated in the LiOH/methanol-based electrolyte. Lead, silver, gold, palladium, copper and nickel were evaluated as deposition metals. With lead, silver, gold and copper-modified p-InP photocathodes, the main products from CO2 were carbon monoxide and formic acid. Maximum current efficiency of carbon monoxide was obtained at silver-modified p-InP photoelectrode (rf = 80.4%). On palladium-deposited p-InP electrode, the reduction product was only carbon monoxide. With nickel-deposited p-InP photoelectrode, hydrocarbons (methane and ethylene) were obtained with low Faradaic efficiencies 0.7% and 0.2%, in addition of the formations of CO and formic acid, respectively. The distribution of reduction products in the photoelectrochemical reduction of CO2 in methanol at metal-modified p-InP photocathodes may be roughly associated with the catalytic property of metallic electrode in the electrochemical CO2 reduction in methanol. This research may contribute to applications in the photochemical conversion and storage of solar energy.