Convergence of Tandem Catalysis and Nanoconfinement Promotes Electroreduction of CO2 to C2 Products

An efficient electrocatalytic conversion of CO2 into valuable multicarbon (C2+) products requires enhanced C-C coupling of C1 intermediates. Herein, we combine a tandem effect with a confinement strategy to construct a hollow Cu2O@Ag nanoshell electrocatalyst with a well-defined porous structure to improve the *CO intermediate coverage on the catalyst surface. In CO2 electroreduction, in situ Raman spectroscopy shows that the introduction of Ag can not only promote the CO intermediate production but also improve the stability of Cu+ to capture the *CO intermediate due to a CO-tandem effect, and the fine-tuned hollowness degree and pore size of Cu2O@Ag create a spatially confined microenvironment for trapping CO2 as well as the enrichment of CO, which greatly facilitate subsequent C-C coupling for C2+ product. The optimized Cu2O@Ag-45 with a specific nanoconfinement exhibits an enhanced ethylene (C2H4) production under the wide potential range from -0.4 to -1.2 V (vs RHE), and a Faradaic efficiency of 55.4% for C2+ products could be achieved at -1.2 V (vs RHE). This study highlights a promising strategy for the electrochemical reduction of CO2 to C2+ products on efficient C-C coupling catalysts.