Boosting Electrochemical Ethylene Epoxidation via Ruthenium Valence State Stabilization

Halide-mediated olefin epoxidation using renewable electricity offers a sustainable route for ethylene oxide (EO) production. However, catalyst deactivation due to excessive oxidation and degradation in halide-rich environments hinders industrial scalability. This paper describes an electron reservoir strategy to stabilize a ruthenium oxide-based catalyst in chloride-rich environments through iridium doping. The electronegativity difference between ruthenium and iridium enables bidirectional electron transfer, mitigating catalyst degradation at high current densities. This strategy achieves a Faradaic efficiency of EO up to 85.1% and stable operation for over 120 h at 150 mA cm^-2. In situ Raman spectroscopy reveals that iridium doping reduces the vibrational frequency disparity between Cl-O and Ru-O bonds, lowering the activation energy for M-O bond cleavage and promoting direct HOCl formation while preventing Cl₂ production. These findings demonstrate the importance of electronic modulation for catalyst design and may inspire new strategies for the sustainable production of chemical feedstocks.