Photoelectrochemical CO2 Reduction to Acetate on Iron–Copper Oxide Catalysts

We demonstrate the ability to convert CO2 to acetate with 80% Faradaic efficiency, using a mixed Fe–Cu oxide catalyst at −0.4 V bias vs Ag/AgCl during visible light illumination. Analysis shows that the selective catalyst is a mixed-phase material consisting of CuFeO2 and CuO. By varying the Fe:Cu atomic fraction from 1.3 to 0.1, it is possible to tune the selectivity for CO2 reduction from primarily acetate to primarily formate. These results identify a new low-cost, Earth-abundant material capable of synthesizing an energy-dense liquid directly from CO2 and show that selectivity for CO2 reduction can be tuned by controlling catalyst composition in mixed Fe–Cu oxide catalysts.