Br, O‐Modified Cu(111) Interface Promotes CO₂ Reduction to Multicarbon Products

Abstract Electrochemical reduction of CO₂ to multicarbon (C₂₊) products with added value represents a promising strategy for achieving a carbon‐neutral economy. Precise manipulation of the catalytic interface is imperative to control the catalytic selectivity, particularly toward C₂₊ products. In this study, a unique Cu/UIO‐Br interface is designed, wherein the Cu(111) plane is co‐modified simultaneously by Br and O from UIO‐66‐Br support. Such Cu/UIO‐Br catalytic interface demonstrates a superior Faradaic efficiency of ≈53% for C₂₊ products (ethanol/ethylene) and the C₂₊ partial current density reached 24.3 mA cm⁻² in an H‐cell electrolyzer. The kinetic isotopic effect test, in situ attenuated total reflection Fourier transform infrared spectroscopy and density functional theory calculations have been conducted to elucidate the catalytic mechanism. The Br, O co‐modification on the Cu(111) interface enhanced the adsorption of CO₂ species. The hydrogen‐bond effect from the doped Br atom regulated the kinetic processes of ^*H species in CO₂RR and promoted the formation of ^*COH intermediate. The formed ^*COH facilitates the ^*CO–^*COH coupling and promotes the C₂₊ selectivity finally. This comprehensive investigation not only provides an in‐depth study and understanding of the catalytic process but also offers a promising strategy for designing efficient Cu‐based catalysts with exceptional C₂₊ products.