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

Electrochemical CO2 reduction reaction (CO2 RR) 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.