In Situ Engineering of the Cu⁺/Cu⁰ Interface to Boost C₂₊ Selectivity in CO₂ Electroreduction

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 FEC2+ 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.