Highly ethylene-selective electrocatalytic CO2 reduction enabled by isolated Cu-S motifs in metal-organic framework-based precatalysts.

Copper-based material is an efficient electrocatalyst for CO2 conversion to C2+ products, most of which will reconstruct to in-situ regenerate active species. It is a challenge to precisely design precatalyst to obtain active sites for CO2 reduction reaction (CO2RR). Herein, we develop a local sulfur doping strategy over the Cu-based metal-organic frameworks precatalyst that disperses stable Cu-S motif in the framework of HKUST-1 (S-HKUST-1). The precatalyst exhibits a high ethylene selectivity in H-type cell with maximum faradaic efficiency (FE) of 60.0%, and delivers a current density of 400 mA cm-2 with ethylene FE to 57.2% in a flow cell. Operando X-ray absorption results demonstrate that Cuδ+ species stabilized by Cu-S motif exist in S-HKUST-1 during CO2RR. Density functional theory calculations indicate the partially oxidized Cuδ+ at Cu/CuxSy interface is favorable for *CO intermediate coupling due to the modest distance of coupling sites and optimized adsorption energy.