In‐Situ Constructuring of Copper‐Doped Bismuth Catalyst for Highly Efficient CO 2 Electrolysis to Formate in Ampere‐Level

Abstract CO 2 electrochemical reduction (CO 2 RR) can mitigate environmental issues while providing valuable products, yet challenging in activity, selectivity, and stability. Here, a CuS‐Bi 2 S 3 heterojunction precursor is reported that can in situ reconstruct to Cu‐doped Bismuth (CDB) electrocatalyst during CO 2 RR. The CDB exhibits an industrial‐compatible current density of −1.1 A cm −2 and a record‐high formate formation rate of 21.0 mmol h −1 cm −2 at −0.86 V versus the reversible hydrogen electrode toward CO 2 RR to formate, dramatically outperforming currently reported catalysts. Importantly, the ultrawide potential region of 1050 mV with high formate Faradaic efficiency of over 90% and superior long‐term stability for more than 100 h at −400 mA cm −2 can also be realized. Experimental and theoretical studies reveal that the remarkable CO 2 RR performance of CDB results from the doping effect of Cu which optimizes adsorption of the *OCHO and boosts the structural stability of metallic bismuth catalyst. This study provides valuable inspiration for the design of element‐doping electrocatalysts to enhance catalytic activity and durability.