Sustained Direct Electro-epoxidation of Ethylene via a Strain-Gradient CuO-Ag Interface

Direct electrochemical ethylene epoxidation using water as the oxygen source offers a sustainable alternative to conventional thermal processes, but practical implementation is constrained by insufficient ethylene adsorption and the inherent instability of the critical OO* intermediate. Here we show that a CuO/Ag catalyst engineered with coupled strain and electronic properties promotes exposure of metastable Ag(111) facets to strengthen ethylene adsorption and establishes a dual-reagent confinement system that enriches H₂O and C₂H₄ at respective interfacial domains. Characterization and simulation reveal that dynamic charge oscillations at the interface induce an electron flow from Ag to CuO, which facilitates C=C bond activation and stabilizes the OO* intermediate by suppressing O-O bond cleavage. In a membrane electrode assembly reactor, a stable ethylene oxide production rate of 345 μmol·cm^-2·h^-1 is achieved at 50 mA·cm^-2 over 60 hours, with a Faradaic efficiency of 45.6% and a selectivity of 92.8%. This work validates interfacial strain and electronic properties as a viable strategy for sustainable electrified synthesis, as exemplified by the continuous direct epoxidation of ethylene.