Chlorine‐dopant dynamically stabilizes Cu⁰/Cu⁺ active sites for selective <scp>CO₂</scp> electroreduction to multicarbon products

Abstract The electrochemical CO 2 reduction reaction (CO 2 RR) to multicarbon (C 2+ ) products faces significant challenges rooted in the high energy barriers of C–C coupling, which can be addressed through dopant‐mediated stabilization of Cu + species on Cu catalysts. Here, we present an in‐situ chlorine (Cl) doping strategy achieving dynamic stabilization of Cu 0 /Cu + active sites, consequently resulting in an improved selectivity for C 2+ product with a partial current density of 280 mA cm −2 . In‐situ x‐ray diffraction (XRD) and ex‐situ x‐ray photoelectron spectroscopy (XPS) analyses confirmed sustained Cu + species and Cl dopant retention throughout CO 2 RR operation and membrane electrode assembly (MEA) durability assessment (over 55 h). Theoretical study demonstrated that Cl‐dopant could extract electrons from Cu during CO 2 RR to dynamically produce Cu 0 /Cu + active sites to lower the free energy toward CO 2 RR and improve the adsorption of *CO and *CHO intermediates, which is key for the CC coupling. Our findings demonstrate that Cl‐dopant serves as an efficient electron extractor for generating Cu + species, thereby emphasizing the efficacy of the in‐situ doping strategy in creating a high density of stable interfacial Cu 0 /Cu + active sites.