Manipulation of Oxygen Species on an Antimony-Modified Copper Surface to Tune the Product Selectivity in CO 2 Electroreduction.

Rational regulation of the electrochemical CO 2 reduction reaction (CO 2 RR) pathway to produce desired products is particularly interesting, yet designing economical and robust catalysts is crucial. Here, we report an antimony-modified copper (CuSb) catalyst capable of selectively producing both CO and multicarbon (C 2+ ) products in the CO 2 RR. At a current density of 0.3 A/cm 2 , the faradaic efficiency (FE) of CO was as high as 98.2% with a potential of -0.6 V vs reversible hydrogen electrode (RHE). When the current density increased to 1.1 A/cm 2 at -1.1 V vs RHE, the primary products shifted to C 2+ compounds with a FE of 75.6%. Experimental and theoretical studies indicate that tuning the potential could manipulate the oxygen species on the CuSb surface, which determined the product selectivity in the CO 2 RR. At a more positive potential, the existence of oxygen species facilitates the potential-limiting step involving *COOH formation and reduces the adsorption of *CO intermediates, thereby promoting CO production. At a more negative potential, the localized high CO concentration coupled with the enhanced adsorption of *CO intermediates due to Sb incorporation facilitates C-C coupling and deep hydrogenation processes, resulting in an increased C 2+ selectivity.