Regulating selectivity of high-rate CO electroreduction on bimetallic catalysts

CO electroreduction reaction (CORR) provides a green and sustainable route for CO conversion. The modulation of CO adsorption and hydrogenation as well as the C–C coupling is of paramount importance for optimizing CORR selectivity. In this work, Ce and Sn are introduced to Cu-based materials to prepare bimetallic catalysts. The obtained Cu-sg-Ce provides a high Faradaic efficiency of C_{2 +} products (FE_C2+) of 87.6 % while Cu-sg-Sn exhibits a high FE of CH₄ of 48.3 %. Particularly, a very high partial current density (j) of C₂₊ products (–780.3 mA cm^–2) is achieved on Cu-sg-Ce. Mechanistic studies demonstrate that the introduction of CeO₂ enhances the adsorption strength and capacity of CO. With sufficient local concentration of adsorbed CO (*CO) and improved *CO hydrogenation with higher overpotential, the matching between *CO hydrogenation and C–C coupling on Cu-sg-Ce was improved, which leads to high FE_C2+ at high j on Cu-sg-Ce. By contrast, the introduction of Sn leads to a longer Cu-Cu distance, which significantly enhances the adsorption strength toward CO and meanwhile weakens the capability of C–C coupling. It results in continuous hydrogenation of *CO to give CH₄ on Cu-sg-Sn.