Manipulation of Oxygen Species on an Antimony-Modified Copper Surface to Tune the Product Selectivity in CO2 Electroreduction

Abstract

Rational regulation of the electrochemical CO₂ reduction reaction (CO₂RR) 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 (C₂₊) products in the CO₂RR. At a current density of 0.3 A/cm², 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/cm² at −1.1 V vs RHE, the primary products shifted to C₂₊ 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 CO₂RR. 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 C₂₊ selectivity.