A tandem electrochemical–chemical system that couples CO₂ reduction (CO₂R) toward C₂H₄ and two-electron water electrooxidation (2e-WOR) toward H₂O₂ in a single electrolyzer with ambient epoxidation was reported to produce ethylene oxide (EO) from CO₂ and H₂O.

Abstract

Ethylene oxide (EO) is an important commodity chemical, and its production currently relies on fossil fuel-based energy-intensive thermocatalysis associated with substantial CO₂ emissions or the usage of toxic/corrosive precursors (e.g., Cl₂). Herein, we report a convergent electrochemical–chemical tandem route for efficient synthesis of EO from CO₂ and water under ambient conditions over nonprecious catalysts. Such a protype consists of cathodic CO₂ electroreduction to C₂H₄ and simultaneous anodic two-electron water electrooxidation (2e-WOR) to H₂O₂ in a single electrolyzer, followed by reaction of the two products over titanium silicalite-1 (TS-1) catalyst toward EO with high production rate of 422.3 µmol h⁻¹ and high selectivity of >98%. W-doped CuO_x and Cu-doped SnO₂ were used as cathode and anode electrodes with respective Faradaic efficiencies of 63.5% and 75.6% at 800 mA cm⁻². Systematic characterizations, including ¹¹⁹Sn Mössbauer spectroscopy, quasi-in situ electron paramagnetic resonance (EPR), isotope-labeling mass spectrometry (MS), and operando infrared spectroscopy, along with theoretical calculations, reveal that Cu doping breaks the electronic structure symmetry of Sn to induce electron redistribution for optimal adsorption and coupling of key intermediates like *OH in 2e-WOR. This study offers a sustainable manner for efficient EO synthesis from raw materials with renewable electricity input.