Interfacial polarization enables dual pathways for electrosynthesis of propyl acetate

The direct electrosynthesis of value-added esters from carbon monoxide (CO) represents a promising strategy for sustainable carbon utilization. In this study, we report the synthesis of propyl acetate with a faradaic efficiency of 16.5% and a partial current density reaching up to 24.7 mA cm^-2 <i>via</i> CO electrolysis on a polarized Cu/Cu₃N interface. Comprehensive mechanistic investigations elucidate a dual-pathway mechanism: ketene undergoes nucleophilic addition with <i>n</i>-propanol; and C₂-C₃ coupling occurs between nucleophilic *CH₂CO and electrophilic intermediates such as *COHCOCO. Charge redistribution and interfacial polarization induced by the Cu/Cu₃N interface reduce the activation barrier for the electrophilic addition between C₂-C₃ intermediates. These findings offer an alternative and sustainable pathway for the synthesis of esters through direct CO electroreduction.