Surface Reconstruction with a Sandwich-like C/Cu/C Catalyst for Selective and Stable CO₂ Electroreduction

For the steady electroreduction of carbon dioxide (CO₂RR) to value-added chemicals with high efficiency, the uncontrollable surface reconstruction under highly reducing conditions is a critical issue in electrocatalyst design. Herein, we construct a catalyst model with a sandwich-like structure composed of highly reactive metallic Cu nanosheet that is confined in thin carbon layers (denoted as C/Cu/C nanosheet). The sandwich-like C/Cu/C nanosheet avoids the oxidation of the active site of metallic Cu at an ambient atmosphere owing to the protective coating of the carbon layer, which inhibits the surface reconstruction that occurs via the dissolution of copper oxides and redeposition of dissolved Cu ions. The as-prepared C/Cu/C nanosheet exhibits a prominent Faradaic efficiency (FE) of 47.8% for CH₄ products at -1.0 V with a current density of 20.3 mA·cm^-2 and stable production of CH₄ during 12 h operation with negligible selectivity loss. Our findings provide an effective strategy of restraining surface reconstruction for the design of selective and stable electrocatalysts toward CO₂RR.