Electrochemical Reduction of CO₂ Toward C₂ Valuables on Cu@Ag Core-Shell Tandem Catalyst with Tunable Shell Thickness

Electrochemical CO₂ reduction reaction (CO₂RR) is critical to converting CO₂ to high-value multicarbon chemicals. However, the Cu-based catalysts as the only option to reduce CO₂ into C₂₊ products suffer from poor selectivity and low activity. Tandem catalysis for CO₂ reduction is an efficient strategy to overcome such problems. Here, Cu@Ag core-shell nanoparticles (NPs) with different silver layer thicknesses are fabricated to realize the tandem catalysis for CO₂ conversion by producing CO on Ag shell and further achieving C–C coupling on Cu core. It is found that Cu@Ag-2 NPs with the proper thickness of Ag shell exhibit the Faradaic efficiency (FE) of total C₂ products and ethylene as high as 67.6% and 32.2% at −1.1 V (versus reversible hydrogen electrode, RHE), respectively. Moreover, it exhibits remarkably electrocatalytic stability after 14 h. Based on electrochemical tests and CO adsorption capacity analyses, the origin of the enhanced catalytic performance can be attributed to the synergistic effect between Ag shell and Cu core, which strengthens the bonding strength of CO on Cu/Ag interfaces, expedites the charge transfer, increases the electrochemical surface areas (ECSAs). This report provides a Cu-based catalyst to realize efficient C₂ generation via a rationally designed core-shell structured catalyst.