Confinement Catalysis\nof Reaction Intermediates in\nAg@Cu<sub>2</sub>O Cascade Nanoreactors toward Boosted Electrochemical\nC–C Coupling

Cascade nanoreactors provide an ideal platform for multicomponent\nsequential reactions and synergistic transformations. However, the\neffects of morphology modulation on confinement catalysis, particularly\nregarding the generation, diffusion, and dimerization of reaction\nintermediates in CO<sub>2</sub>RR are less discerned. Herein, we synthesized\na series of Ag@Cu<sub>2</sub>O cascade nanoreactors with tunable shell\nthicknesses by a two-step seeded growth method, observing an obvious\nvolcano-type curve in C<sub>2+</sub> products generation. The variant\nwith a medium shell thickness (Ag@Cu<sub>2</sub>O-40) achieved the\nhighest Faradaic efficiency (FE) of C<sub>2+</sub> up to 78.5% at\n−1.6 V (vs RHE). In situ Raman and density functional theory\n(DFT) calculations indicate that CO generated on the Ag core spills\nover and becomes confined at the Cu<sub>2</sub>O shell, which is crucial\nin boosting C–C coupling rather than forming C<sub>1</sub> products\n(CO, CH<sub>3</sub>OH, and CH<sub>4</sub>). Finite element method\n(FEM) simulations further reveal that the optimal thickness of the\nCu<sub>2</sub>O shell accommodates CO<sub>2</sub> diffusion and CO\nconfinement capabilities, thereby maximizing CO concentration for\nthe formation of C<sub>2+</sub> products. Our findings exemplify the\npotential of rationally designed cascade nanoreactors for optimizing\nreaction intermediates through confinement catalysis.