Cu‐In Dual Sites with Sulfur Defects toward Superior Ethanol Electrosynthesis from CO2 Electrolysis

Abstract The electrosynthesis of multi‐carbon chemicals from excess carbon dioxide (CO 2 ) is an area of great interest for research and commercial applications. However, improving both the yield of CO 2 ‐to‐ethanol conversion and the stability of the catalyst at the same time is proving to be a challenging issue. Here it is proposed to stabilize active Cu(I) and In dual sites with sulfur defects through an electro‐driven intercalation strategy, which leads to the delocalization of electron density that enhances orbital hybridizations between the Cu‐C and In‐H bonds. Hence, the energy barrier for the rate‐limiting *CHO formation step is reduced toward the key *OCHCHO* formation during ethanol production, which is also facilitated by the combined Cu site enabling C‐C coupling and In site with a higher oxygen affinity based on both thermodynamic and kinetic calculations. Accordingly, such dual‐site catalyst achieves a high partial current density toward ethanol of 409 ± 15 mA cm⁻ 2 for over 120 h. Furthermore, a scaled‐up flow cell is assembled with an industrial‐relevant current of 5.7 A for over 36 h, in which the carbon loss is less than 2.5% and single‐pass carbon efficiency is ≈19%.