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.