The Cu+/Cu0 interface in the Cu-based electrocatalyst is essential to promote the electrochemical reduction of carbon dioxide (ERCO2) to produce multi-carbon hydrocarbons and alcohols with high selectivity. However, due to the high activity of the Cu+/Cu0 interface, it is easy to be oxidized in the air. How to control and prepare a Cu-based electrocatalyst with an abundant and stable Cu+/Cu0 interface in situ is a huge challenge. Here, combined with density functional theory (DFT) calculations and experimental studies, we found that the trace halide ions adsorbed on Cu2O can slow the reduction kinetics of Cu+ → Cu0, which allowed us to in-situ well control the synthesis of the CuO-derived electrocatalyst with rich Cu+/Cu0 interfaces. Our Cu catalyst with a rich Cu+/Cu0 interface exhibits excellent ERCO2 performance. Under the operation potential of -0.98 V versus RHE, the Faraday efficiency of C2H4 and C2+ products are 55.8 and 75.7%, respectively, which is about 16% higher than that of CuO-derived electrocatalysts that do not use halide ions. The high comes from the improvement of the coupling efficiency of reaction intermediates such as CO-CO, which is proved by DFT calculations, and the suppression of hydrogen evolution reaction. Therefore, we provide an in-situ engineering strategy, which is simple and effective for the design and preparation of high-performance ERCO2 catalysts.
Keywords: C2+ product; CO2 electroreduction; Cu+/Cu0 interface; halide; oxide-derived Cu catalysts.