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.
Wang et al. (Tue,) studied this question.