Composition effects of electrodeposited Cu-Ag nanostructured electrocatalysts for CO2 reduction

The electrochemical reduction of carbon dioxide (CO2RR) to valuable C2+ liquid fuels and oxygenates, such as ethanol and propanol, is a promising strategy to minimize the carbon footprint and store renewable electricity. In this study, we investigate the CO2RR on electrodeposited Cu-Ag nanostructures obtained using a green choline chloride and urea deep eutectic solvent (DES). We show that Cu-Ag nanostructured electrocatalysts with tunable composition, loadings, and size can be simply prepared in one step, without adding other additives or surfactant agents. We investigate the intrinsic activity and selectivity of the CO2RR by determining the electrochemically active surface area (ECSA) using lead underpotential deposition (UPD). The analysis of the partial current densities normalized by the ECSA shows that the addition of Ag on electrodeposited Cu primarily suppresses the production of hydrogen and methane with respect to Cu nanostructures. At the same time, the production of carbon monoxide (CO) slightly increases but, the partial current of the total C2+ products does not considerably increase. Despite that the production rate of C2+ is similar on Cu and CuAg, the addition of Ag enhances the formation of alcohols and oxygenates over ethylene, in line with previous reports. We highlight the potential of metal electrodeposition from DES as a sustainable and inexpensive strategy for the development of bimetallic Cu-based nanocatalysts towards CO2RR.