Copper-indium bimetallic catalysts for the selective electrochemical reduction of carbon dioxide

Copper-indium bimetallic catalysts with a dendritic structure are fabricated by a two-step electrodeposition method using a hydrogen evolution template for the CO2 electroreduction reaction (CO2RR). The dendritic Cu-In-30 catalyst electrodeposited for 30 min shows the highest specific surface area and exposes the most active sites, resulting in improved CO2RR activity. The dendritic Cu-In-30 catalyst exhibits distinctly higher formate partial current density (42.0 mA cm−2) and Faradaic efficiency (87.4%) than those of the In-30 catalyst without the dendritic structure (the formate partial current density and Faradaic efficiency are 4.6 mA cm−2 and 57.0%, respectively) at −0.85 V vs. reversible hydrogen electrode, ascribed to the increased specific surface area. The Cu-In-30 catalyst can maintain stable performance for 12 h during the CO2RR. In addition, the intrinsic current density of Cu-In-30 with the dendritic structure (4.8 mA cm−2) is much higher than that of In-30 without the dendritic structure (2.1 mA cm−2), indicating that the dendritic structure promotes the CO2RR, possibly due to additional coordination unsaturated atoms.