Chlorine-induced mixed valence of CuOx/C to promote the electroreduction of carbon dioxide to ethylene

Electrochemical conversion of CO 2 (CO 2 RR) into high-value fuel is identified as one of the promising approaches to achieve carbon neutrality. The synthesis of high-efficiency CO 2 reduction electrocatalysts with high C 2 :C 1 , selectivity remains a field of intense interest. Previous studies have shown that the presence of Cu(I) is beneficial for the reduction of CO 2 into C 2 products. However, the stable presence of Cu(I) remains controversial, especially in the negative potential window. Here we report a simple and easily scalable catalyst precursor Cu 2 (OH) 3 Cl/C, which automatically forms in-situ chlorine-doped Cu/Cu 2 O heterointerface during electrocatalysis. The catalyst not only exhibits a Faradaic efficiency of 33.03% but also provides a long-term stability of Cu + , gaining a stable electrolysis of 11 h, with an ethylene/methane ratio over 50. The experimental results and mechanistic studies confirm that the presence of Cl − inhibits the reduction of Cu + , inducing the formation of Cu 0 /Cu + , and reduces the reaction energy of the intermediate ⋆CO dimerization, thereby facilitating the formation of C 2 products. This work provides a feasible way to synthesize copper ions with long-term and stable positive charge in CO 2 RR and expands a new way to synthesize ethylene industrial products in the future.