Hydroxylation of Cu Sites Enhances Selectivity of Electrosynthesis of Ethanol via Tandem Reduction of CO 2

Abstract Electrochemical conversion of CO 2 into value‐added multi‐carbon products is highly attractive for CO 2 utilization using sustainable electricity energy. However, achieving high ethanol selectivity of copper‐based catalysts remains challenging due to the competing side reactions such as ethylene formation. Herein, a novel electrocatalyst, PANI‐Ag/Cu‐OH is reported, comprising of polyaniline‐supported silver single atoms coupled with hydroxyl‐modified copper clusters. Tandem reduction of CO 2 into ethanol with a high selectivity is realized by coupling CO formation on Ag site and further reduction on hydroxylated Cu sites. The synergistic approach enables a high Faradaic efficiency of 68.9% for ethanol with a current density of −263.8 mA cm −2 at −0.78 V versus RHE in alkaline media. CO‐TPD and in situ infrared spectra studies reveal that strong CO adsorption and Cu + species stabilized by hydroxyl groups are crucial for asymmetric C–C coupling and stabilization of the ethanol intermediates, leading to the enhanced ethanol selectivity.