Ultralow Ag-assisted carbon–carbon coupling mechanism on Cu-based catalysts for electrocatalytic CO2 reduction

Electrocatalytic CO2 reduction to C2H4 supplies an economically viable route for CO2 fixation with the integration of intermittent renewable energy. Cu-based catalysts are capable of catalyzing CO2 to C2H4, while suffering from the high overpotential and low Faradaic efficiency. In this joint experimental-computational work, an Ag-assisted carbon–carbon coupling is exploited on Cu-based catalysts. A systematic characterization analysis suggests that an ultralow quantity of Ag atoms in the Cu catalysts motivates electron transfer from Cu to Ag, regulating the electronic state of highly dispersed Ag. Meanwhile, the Ag incorporation provokes the formation of more oxygen defects on the catalyst surface, improving the adsorption and activation of CO2 molecules. Density functional theory studies prove the improvement effect of Ag for CO2 to COOH*. *CO hydrogenation is energetically more favorable than *CO dimerization pathway, and two *CHO dimerization produces *OCHCHO* key intermediates, which greatly reduces the energy barrier for C2H4 formation.