In Situ Engineering of the Cu/Cu Interface to Boost C Selectivity in CO Electroreduction.

The Cu/Cu interface in the Cu-based electrocatalyst is essential to promote the electrochemical reduction of carbon dioxide (ERCO) to produce multi-carbon hydrocarbons and alcohols with high selectivity. However, due to the high activity of the Cu/Cu 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/Cu 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 CuO can slow the reduction kinetics of Cu → Cu, which allowed us to in-situ well control the synthesis of the CuO-derived electrocatalyst with rich Cu/Cu interfaces. Our Cu catalyst with a rich Cu/Cu interface exhibits excellent ERCO performance. Under the operation potential of -0.98 V versus RHE, the Faraday efficiency of CH and C 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 ERCO catalysts.