アイテム詳細

要旨

As a sustainable pathway for energy storage and to close the carbon cycle, CO₂ electroreduction has recently gained significant interest. We report here the role of the electrolyte, in particular of halide ions, on O₂ electroreduction over plasma-oxidized polycrystalline Cu foils. It was observed that halide ions such as I⁻ can induce significant nanostructuring of the oxidized Cu surface, even at open circuit potential, including the formation of Cu crystals with welldefined shapes. Furthermore, the presence of Cl⁻, Br⁻, and I⁻ was found to lower the overpotential and to increase the CO₂ electroreduction rate on plasma-activated preoxidized Cu catalyst in the order Cl⁻, Br⁻ < I⁻, without sacrificing their intrinsically high C₂−C₃ product selectivity (∼65% total Faradaic efficiency at −1.0 V vs RHE). This enhancement in catalytic performance is mainly attributed to the specific adsorption of halides with a higher coverage on our oxidized Cu surface during the reaction, which have been previously reported to facilitate the formation and stabilization of the carboxyl (*COOH) intermediate by partial charge donation from the halide ions to CO₂.