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

Photoelectrochemical catalyst systems are often plagued either 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. To test this strategic design principle, a composite photoelectrode was created by pairing the chalcopyrite semiconductor CuInSe2 with a known CO2-reducing electrocatalyst, Ni3Al, in an attempt to selectively generate highly reduced products from CO2. This catalytically mismatched system produced methanol at a Faradaic efficiency 25 times greater than that achieved using the purely electro-chemical Ni3Al system while reducing the operating potential requirement by 600 mV when compared to the same catalyst operating on a glassy carbon electrode. These results suggest that designing multi-component photoelectrodes by incorporating catalytic mismatch is a promising tactic to a...