Sustainable Formate Synthesis: Integrating Ethylene Glycol Oxidation with Carbon Dioxide Electrocatalysis Using Redox-Stabilized Earth-Abundant Electrodes

Carbon dioxide electroreduction (CO₂ER) coupled with water oxidation (oxygen evolution reaction, OER) presents a promising solution for effectively mitigating global warming. However, this process is compromised by the sluggish OER, which yields only undesirable O₂. Here, we couple selective CO₂ER with partial ethylene glycol oxidation (EGO) to concurrently produce formate in both half-reactions. The enhancement of active sites and optimization of formate selectivity are the principal objectives during the design of both electrodes. For CO₂ER, redox stabilization of Sn-based cathodes is investigated via Pb doping, thus ultimately improving the Faradaic efficiency from 68% to ∼89%. To replace OER with EGO, we employed CuO@Ni(OH)₂ on copper foam, reducing the applied potential by 200 mV at 50 mA/cm². Finally, an EGO-coupled CO₂ electrolyzer achieves 10 mA/cm² at an overall cell voltage 180 mV lower than that of a conventional CO₂ electrolyzer. This study showcases the integration of divergent electrochemical processes for concurrent electrosynthesis without precious metals to achieve cost-effective and sustainable formate production from CO₂ and plastic waste.