Exploring the mechanistic role of alloying elements in copper-based electrocatalysts for the reduction of carbon dioxide to methane

The promise of electrochemically reducing excess anthropogenic carbon dioxide into useful chemicals and fuels has gained significant interest. Recently, indium-copper (In-Cu) alloys have been recognized as prospective catalysts for the carbon dioxide reduction reaction (CO2RR), although they chiefly yield carbon monoxide. Generating further reduced C1 species such as methane remains elusive due to a limited understanding of how In-Cu alloying impacts electrocatalysis. In this work, we investigated the effect of alloying In with Cu for CO2RR to form methane through first-principles simulations. Compared with pure copper, In-Cu alloys suppress the hydrogen evolution reaction while demonstrating superior initial CO2RR selectivity. Among the alloys studied, In7Cu10 exhibited the most promising catalytic potential, with a limiting potential of -0.54 V versus the reversible hydrogen electrode. Analyses of adsorbed geometries and electronic structures suggest that this decreased overpotential arises primarily from electronic perturbations around copper and indium ions and carbon-oxygen bond stability. This study outlines a rational strategy to modulate metal alloy compositions and design synergistic CO2RR catalysts possessing appreciable activity and selectivity.