Approaching a high-rate and sustainable production of hydrogen peroxide: oxygen reduction on Co–N–C single-atom electrocatalysts in simulated seawater

Abstract

Electrochemical production of H₂O₂ from O₂ using simulated seawater provides a promising alternative to the energy-intensive industrial anthraquinone process. In this study, a flow cell system is built for electrocatalytic production of H₂O₂ under an air atmosphere in simulated seawater using cobalt single-atom catalysts (Co SACs). The Co SACs can achieve a high H₂O₂ production rate of 3.4 mol g_catalyst⁻¹ h⁻¹ under an air flow at a current density of 50 mA cm_geo⁻² and long-term stability over 24 h in 0.5 M NaCl. It is found that Co–N₅ rather than the Co–N₄ structure in Co SACs is the main active site for H₂O₂ formation in the two-electron oxygen reduction reaction (ORR) pathway. It also shows high chloride-endurability without inhibition of the ORR process in simulated seawater. The fast production of H₂O₂ on Co–N₅ sites in a flow cell provides a promising path of electrocatalytic oxygen reduction in simulated seawater, eventually converting ubiquitous air and seawater towards energy sustainability.