Huang, L.Bao, D.Zheng, Y.Qiao, S.-Z.2025-10-212025-10-212025ACS Energy Letters, 2025; 10(8):3907-39132380-81952380-8195https://hdl.handle.net/2440/147895Electrochemical oxidation of ethylene-to-ethylene glycol offers a sustainable alternative to energy-intensive thermal processes. However, current strategies using chloride-mediated electrooxidation of ethylene suffer from low selectivity and efficiency. Here, we report a CrOₓ−IrO₂ catalyst that achieves a faradaic efficiency (FE) of 98.5% with an unprecedent ∼100% selectivity for ethylene glycol on the anode. This catalyst preferentially promotes direct *Cl adsorption on Ir sites and enhances *ClO intermediate coverage during 2-chloroethanol formation, the key precursor to ethylene glycol, while suppressing the competing *OOH pathway. Coupled with cathodic H₂O₂-mediated ethylene oxidation in an electrolyzer, this system reaches ∼100% product selectivity at both the anode and cathode, with a total production rate of 2.69 mmol cm⁻² h⁻¹. Compared to conventional systems that utilize either chloride or H₂O₂ as individual mediators, this dual-mediator strategy achieves energy savings of approximately 52 and 76%, respectively, enabling a scalable and efficient platform for ethylene glycol production from ethylene.en© 2025 American Chemical SocietyAlcohols; Electrodes; Hydrocarbons; Oxidation; SeawaterJournal article10.1021/acsenergylett.5c01654746191Zheng, Y. [0000-0002-2411-8041]Qiao, S.-Z. [0000-0002-1220-1761] [0000-0002-4568-8422]