Convergence of Tandem\nCatalysis and Nanoconfinement\nPromotes Electroreduction of CO<sub>2</sub> to C<sub>2</sub> Products

An efficient electrocatalytic conversion of CO<sub>2</sub> into\nvaluable multicarbon (C<sub>2+</sub>) products requires enhanced C–C\ncoupling of C1 intermediates. Herein, we combine a tandem effect with\na confinement strategy to construct a hollow Cu<sub>2</sub>O@Ag nanoshell\nelectrocatalyst with a well-defined porous structure to improve the\n*CO intermediate coverage on the catalyst surface. In CO<sub>2</sub> electroreduction, in situ Raman spectroscopy shows that the introduction\nof Ag can not only promote the CO intermediate production but also\nimprove the stability of Cu<sup>+</sup> to capture the *CO intermediate\ndue to a CO-tandem effect, and the fine-tuned hollowness degree and\npore size of Cu<sub>2</sub>O@Ag create a spatially confined microenvironment\nfor trapping CO<sub>2</sub> as well as the enrichment of CO, which\ngreatly facilitate subsequent C–C coupling for C<sub>2+</sub> product. The optimized Cu<sub>2</sub>O@Ag-45 with a specific nanoconfinement\nexhibits an enhanced ethylene (C<sub>2</sub>H<sub>4</sub>) production\nunder the wide potential range from −0.4 to −1.2 V (vs\nRHE), and a Faradaic efficiency of 55.4% for C<sub>2+</sub> products\ncould be achieved at −1.2 V (vs RHE). This study highlights\na promising strategy for the electrochemical reduction of CO<sub>2</sub> to C<sub>2+</sub> products on efficient C–C coupling catalysts.