Highly Ethylene‐Selective Electrocatalytic CO 2 Reduction Enabled by Isolated Cu−S Motifs in Metal–Organic Framework Based Precatalysts

Abstract Copper‐based materials are efficient electrocatalysts for the conversion of CO 2 to C 2+ products, and most these materials are reconstructed in situ to regenerate active species. It is a challenge to precisely design precatalysts to obtain active sites for the CO 2 reduction reaction (CO 2 RR). Herein, we develop a strategy based on local sulfur doping of a Cu‐based metal–organic framework precatalyst, in which the stable Cu−S motif is dispersed in the framework of HKUST‐1 (S‐HKUST‐1). The precatalyst exhibits a high ethylene selectivity in an H‐type cell with a maximum faradaic efficiency (FE) of 60.0 %, and delivers a current density of 400 mA cm −2 with an ethylene FE up to 57.2 % in a flow cell. Operando X‐ray absorption results demonstrate that Cu δ+ species stabilized by the Cu−S motif exist in S‐HKUST‐1 during CO 2 RR. Density functional theory calculations indicate the partially oxidized Cu δ+ at the Cu/Cu x S y interface is favorable for coupling of the *CO intermediate due to the modest distance between coupling sites and optimized adsorption energy.