Electrosynthesis of ethylene glycol from ethylene coupled with CO₂ capture

Current ethylene glycol (EG) production generates 46 million metric tons of CO₂ equiv. emission annually. While electrified synthesis could decarbonize this process, existing ethylene oxidation systems suffer from high energy consumption resulting from excessive voltages. Here we identify, with the aid of in situ photoluminescence spectroscopy, an increased pH at the membrane–anode interface within a membrane–electrode assembly electrolyser and find that it arises due to hydroxide counter-migration across the membrane. To address this challenge, we integrate cathodic electrochemical carbon capture to reduce hydroxide flux and develop RuSnO_x catalysts that favour *Cl over *OH adsorption, facilitating chloride-mediated ethylene oxidation. The system achieves 94% Faradaic efficiency for ethylene-to-EG conversion and 91% CO₂ capture efficiency from a 10% CO₂ stream, sequestering 0.60 tonnes CO₂ per tonne of EG produced from ethylene. This approach results in an estimated carbon intensity of 0.133 tonnes CO₂ equiv. per tonne EG, compared with the global average of 1.2 tonnes CO₂ equiv. per tonne EG. (Figure presented.)