Enhancing Electrochemical CO₂ Reduction Activity via Charge Transfer and sp-Band Filling in a Au Thin Layer on Ag

Producing practical chemical feedstocks via electrochemical CO2 reduction is a promising technology for carbon recycling and renewable energy storage. To improve CO2 reduction performance, electrocatalysts with high activity and selectivity must be developed. In this study, Au layers of varying thicknesses were sputtered on polycrystalline Ag catalysts to promote the selective reduction of CO2 to CO. The results show that a 2 nm Au layer sputtered on polycrystalline Ag exhibited a faradaic efficiency of 83.9% at −0.9 V versus the reversible hydrogen electrode with a current density of 5.93 mA cm–2. The superior performance of the layered catalyst resulted from the facile charge transfer from Ag to Au, which enhanced the catalytic activity. Furthermore, because the increased electron population in the sp-band resulted in strong CO surface interactions, the layered catalyst exhibited enhanced selectivity for CO production. Thus, this study presents an efficient approach to develop effective layered catalysts for electrochemical CO2 reduction.