Electrochemical epoxidation enhanced by C₂H₄ activation and hydroxyl generation at the Ag/SnO₂ interface

Direct electrochemical ethylene (C₂H₄) epoxidation with water (H₂O) represents a promising approach for the production of value-added ethylene oxide (EO) in a sustainable way. However, the activity remains limited due to the sluggish activation of C₂H₄ and the stiff formation of *OH intermediate. This paper describes the design of a Ag/SnO₂ electrocatalyst to achieve efficient electrochemical C₂H₄ epoxidation with a high faradaic efficiency of 39.4% for EO and a high selectivity of 91.5% at 25 mA/cm² in a membrane electrode assembly. Results of in situ attenuated total reflection infrared spectra characterizations and computational calculations reveal that the Ag/SnO₂ interface promotes C₂H₄ adsorption and activation to obtain *C₂H₄. Moreover, electrophilic *OH is generated on the catalyst surface through H₂O dissociation, which further reacts with *C₂H₄ to facilitate the formation of *C₂H₄OH, contributing to the enhanced electrochemical epoxidation activity. This work would provide general guidance for designing catalysts for electrochemical olefin epoxidation through interface engineering.