Co-electrolysis of ethylene glycol and carbon dioxide for formate synthesis

Co-electrolysis of waste plastics and carbon dioxide (CO₂) into value-added chemicals or fuels is a promising pathway for a sustainable society, but efficient and selective conversion remains a challenge. Herein, a gold-mediated nickel hydroxide (Au/Ni(OH)₂) is developed to oxidize waste plastic-derived ethylene glycol (EG) into formate. In-situ electrochemical experiments and theoretical results reveal that the introduction of Au favors the redox properties and EG adsorption behavior of Ni(OH)₂. The Au/Ni(OH)₂ catalyst shows an excellent formate selectivity of >90% at high current densities of above 100 mA cm⁻². When coupled with sputtered bismuth (Bi) cathode for CO₂ reduction, a high formate Faradic efficiency (FE) of 188.2% at 200 mA cm⁻² and a good formate productivity of 7.33 mmol m⁻² s⁻¹ at 10 A are obtained in a flow cell and a zero-gap membrane electrode assembly (MEA) cell, respectively. This work demonstrates a promising strategy to convert waste plastics and CO₂ into valuable products.