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Electrochemical conversion of CO 2 into value-added chemicals continues to draw interest in renewable energy applications. Although many metal catalysts are active in the CO 2 reduction reaction (CO 2 RR), their reactivity and selectivity are nonetheless hindered by the competing hydrogen evolution reaction (HER). The competition of the HER and CO 2 RR stems from the energy scaling relationship between their reaction intermediates. Herein, we predict that bimetallic monolayer electrocatalysts (BMEs) – a monolayer of transition metals on top of extended metal substrates – could produce dual-functional active sites that circumvent the scaling relationship between the adsorption energies of HER and CO 2 RR intermediates. The antibonding interaction between the adsorbed H and the metal substrate is revealed to be responsible for circumventing the scaling relationship. Based on extensive density functional theory (DFT) calculations, we identify 11 BMEs which are highly active and selective toward the formation of formic acid with a much suppressed HER. The H–substrate antibonding interaction also leads to superior CO 2 RR performance on monolayer-coated penta-twinned nanowires. 

Two-dimensional (2D) materials are full of surprises and fascinating potential. Motivated by a recent discovery that sub-nanometer PdMo bimetallenes can realize exceptional performance in the oxygen reduction reaction [ Nature 2019, 574 , 81–85], we explore the potential of 2D bimetallenes for catalyzing the CO 2 electroreduction reaction (CO 2 RR). Following extensive first-principles calculations on more than a hundred bimetallenes, we identify 17 Cu- and Ag-based bimetallenes, which are highly active and selective toward the formation of formic acid and simultaneously suppress the competing hydrogen evolution reaction. Equally important, we find that CO 2 RR products via intermediates of COOH and CO are disfavored on these bimetallenes. Although surface strains are developed on the bimetallenes, their contribution to the catalytic activities is moderate as compared to that of the alloying effect. This work opens the door to future applications of bimetallenes as active and selective catalysts for the CO 2 RR.