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.