CuC(O) Interfaces Deliver Remarkable Selectivity and Stability for CO 2 Reduction to C 2+ Products at Industrial Current Density of 500 mA cm −2

Abstract The electrocatalytic CO 2 reduction reaction (CO 2 RR) is an attractive technology for CO 2 valorization and high‐density electrical energy storage. Achieving a high selectivity to C 2+ products, especially ethylene, during CO 2 RR at high current densities (>500 mA cm −2 ) is a prized goal of current research, though remains technically very challenging. Herein, it is demonstrated that the surface and interfacial structures of Cu catalysts, and the solid–gas–liquid interfaces on gas‐diffusion electrode (GDE) in CO 2 reduction flow cells can be modulated to allow efficient CO 2 RR to C 2+ products. This approach uses the in situ electrochemical reduction of a CuO nanosheet/graphene oxide dots (CuOC(O)) hybrid. Owing to abundant CuOC interfaces in the CuOC(O) hybrid, the CuO nanosheets are topologically and selectively transformed into metallic Cu nanosheets exposing Cu(100) facets, Cu(110) facets, Cu[ n (100) × (110)] step sites, and Cu + /Cu 0 interfaces during the electroreduction step, the faradaic efficiencie (FE) to C 2+ hydrocarbons was reached as high as 77.4% (FE ethylene ≈ 60%) at 500 mA cm −2 . In situ infrared spectroscopy and DFT simulations demonstrate that abundant Cu + species and Cu 0 /Cu + interfaces in the reduced CuOC(O) catalyst improve the adsorption and surface coverage of *CO on the Cu catalyst, thus facilitating CC coupling reactions.