Carbon Monoxide Oxidation Enables Energy-Efficient Hydrogen Peroxide and Carbonate Coproduction from CO-Rich Flue Gas and Air

Abstract The electrochemical carbon monoxide oxidation reaction (COOR) is an attractive anodic alternative to the oxygen evolution reaction, offering a route to lower the energy demand of electrosynthesis while utilizing abundant industrial waste gas. However, COOR has rarely been implemented in practical paired electrolysis systems because of modest device-level performance, reliance on purified CO feedstocks, and operational instability. Here, we establish a COOR∥two-electron oxygen reduction reaction paired electrolysis platform for H2O2 and CO32– coproduction using simulated CO-rich steelmaking flue gas. The system sustains bias-free operation for >140 h. Under high-current-density operation, in situ surface analysis revealed that interfacial carbonate accumulation causes anodic passivation and current decay. Pulsed electrolysis was introduced to alleviate such carbonate buildup and stabilized operation at 100 mA cm–2. Techno-economic analysis estimated an H2O2 minimum selling price of $0.71 kg–1. Together, these results establish COOR as a practical strategy for energy-efficient electrosynthesis using industrial waste gas.