Prospects and Promises in Two-Electron Water Oxidation for Hydrogen Peroxide Generation

A key oxidizing agent for the chemical industry, wastewater treatment, and semiconductor development is hydrogen peroxide (H2O2). Electrochemical (EC) and photoelectrochemical (PEC) production of H2O2 syntheses have been studied as promising alternatives to the unsustainable anthraquinone oxidation process and the H2 and O2 direct gas synthesis route. While cathodic O2 reduction to produce H2O2 draws more extensive attention than anodic water oxidation due to the higher obtained indicator of Faraday efficiency and production rate of H2O2, however, in the long term, using water as a raw material for water oxidation is a desirable procedure for the sustainable development of H2O2 production. To inspire innovative ideas for boosting the H2O2 yield in photo/electrocatalysis, we review recent advancements in EC/PEC H2O2 production from experimental and computational points of view. The fundamental mechanism of the process, rational design of the electrode, and advanced engineering strategies for enhancement of H2O2 production via a two-electron water oxidation reaction (2e– WOR) are thoroughly summarized. Furthermore, we discuss the hindrances and challenges of 2e– WOR, including all intermediates and competing reaction routes, integrate tandem device development, and the H2O2 degradation issues for better addressing. 2e– WOR enables more excellent H2O2 production rates with optimal efficiency.