Manipulating Metal Cations Microenvironment for Highly Selective Electrochemical Water Oxidation to Hydrogen Peroxide

Electrochemical two-electron water oxidation (2e– WOR) represents a promising approach for the renewable and on-site production of H2O2, potentially replacing the anthraquinone process. Nevertheless, it faces intense competition from the conventional four-electron oxygen evolution reaction (OER), resulting in low selectivity, high overpotential, and low yield. Herein, taking carbon-based structures with 2e– WOR selectivity as model catalysts, by manipulating the electrolyte, it increased the maximum Faraday efficiency of H2O2 to 71 ± 3%, with an H2O2 production rate of 11.7 μmol cm–2 min–1. The 2e– WOR activity was found to be most sensitive to alkali metal cations in the following order: Cs+ > K+ > Na+ > Li+. In situ spectroscopy characterization confirmed that larger cations facilitate the generation of peroxide species; this is because, on one hand, cations can regulate the electronic activity of the catalyst sites and improve the adsorption of the reaction intermediates; on the other hand, the cation-hydrogen oxygen interaction regulates the stable coordination of the cation, realizes the reforming of the hydrogen bond network, and prevents its further water oxidation into O2. With the help of a flow electro-synthetic cell, we can successfully achieve the rapid degradation of organic pollutants in water and the preparation of solid H2O2 (sodium peroxycarbonate). This work not only enriches the understanding of cationic and 2e– WOR mechanisms but also provides implications for rational optimization strategies of the electrode/electrolyte interface.