Abstract
Cu-based bimetallic catalysts have been shown to improve the multi-carbon (C(2+)) selectivity in CO(2) electroreduction, with the assumption that CO spillover from the CO-selective catalysts to adjacent Cu domains via their bimetallic interface promotes C-C coupling. Here, through systematically controlling the Cu-Ag interface densities of bimetallic catalysts, we report that CO spillover via the bimetallic interface is unlikely to enhance the formation of C(2+) products. Conversely, the abundant Cu-Ag interface preferentially promotes CH(4) formation while suppressing C─C bond formation. CO stripping studies also reveal that the Cu-Ag interface does not favor C─C coupling. Further computational modelling suggests that Cu-Ag bimetallic interface significantly enhances the energy barrier of CO dimerization while lowering the energy barrier for (*)CO hydrogenation toward CH(4), thus inhibiting C─C coupling toward C(2+) products while facilitating CH(4) formation.