Catalytic Mismatching of CuInSe2 and Ni3Al Demonstrates Selective Photoelectrochemical CO2 Reduction to Methanol

Photoelectrochemical catalysts are often plagued by ineffective interfacial charge transfer or nonideal optical conversion properties. To overcome this challenge, strategically pairing a catalytically inactive, optically proficient semiconductor with a selective electrocatalyst, coined catalytic mismatching, is suggested. Here, chalcopyrite semiconductor CuInSe2 is paired with the electrocatalyst Ni3Al to selectively reduce CO2. This catalytically mismatched system produces methanol at a Faradaic efficiency 25 times greater than that achieved using the purely electrochemical Ni3Al system while reducing the operating potential requirement by 600 mV. These results suggest that catalytic mismatching is a promising tactic to achieve reaction selectivity in synergistic photoelectrochemical CO2 reduction systems.