A Cs+ and sulfur vacancy co-modified Cu2S (Cs-VS-Cu2S) catalyst promotes *CO adsorption in a bridge-bonded configuration, lowers the *CO-to-*CHO barrier, and stabilizes *CH2CHOH over *CH2CH2O, steering selectivity toward C2H5OH. The catalyst exhibits a 64.5% C2H5OH faradaic efficiency with 150 mA cm-2 and 120 h stability.