Facile Synthesis of Sub‐Nanometric Copper Clusters by Double Confinement Enables Selective Reduction of Carbon Dioxide to Methane

Abstract

Previous density functional theory (DFT) calculations have fully proven that the sub‐nanometric Cu clusters (i.e., 13 atoms) are more favorable for the generation of CH 4 from CO 2 reduction reaction (CO 2 RR) than larger nanoparticles (NPs) due to the upshifted d center. However, it still lacks direct experimental evidence and remains unclear. Herein, we developed a facile impregnation‐calcination route for the crafting of Cu clusters in diameter of ~1.0 nm with ~10 atoms via a double‐confinement of carbon defects and micropores. The obtained Cu clusters enable a high selectivity for the CO 2 RR with a maximum Faraday efficiency of 81.7% towards CH 4 . Both DFT calculations and experimental results reveal that the Cu clusters can enhance the adsorption strength of *H and *CO intermediates and thus promotes the generation of CH 4 other than H 2 and CO, compared with larger Cu nanoparticles (~19 nm). Moreover, the strong interaction between Cu clusters and defective carbon optimizes the electronic structures of Cu clusters for further enhancing the selectivity and stability towards generation of CH 4 . Clearly, this work provides the first experimental evidence that the sub‐nanometric Cu clusters indeed facilitate the production of CH 4 from CO 2 RR.