Solar-driven photoelectrochemical reduction of carbon dioxide to methanol at CuInS2 thin film photocathode

The reduction of CO2 into solar fuel is not only beneficial to the reduction of CO2 emission, but also beneficial to the release of energy shortage. In this study, a solar-driven photoelectrochemical reduction reaction of CO2 to methanol is conducted using a chalcopyrite p-CuInS2 thin film as a photocathode. The CuInS2 thin film is fabricated by electrodeposition of Cu–In alloy layer followed by sulfurization. With pyridinium ion as the co-catalyst, the photoelectrochemical reduction of CO2 to methanol can occur at the overpotential of 20 mV with the faradaic efficiency of 97%.