Recent advances in electrocatalytic oxygen reduction for on-site hydrogen peroxide synthesis in acidic media

Electrocatalytic oxygen reduction reaction (ORR) via two-electron pathway is a promising approach to decentralized and on-site hydrogen peroxide (H2O2) production beyond the traditional anthraquinone process. In recent years, electrochemical H2O2 production in acidic media has attracted increasing attention owing to its stronger oxidizing capacity, superior stability, and higher compatibility with various applications. Here, recent advances of H2O2 electrosynthesis in acidic media are summarized. Specifically, fundamental aspects of two-electron ORR mechanism are firstly presented with an emphasis on the pH effect on catalytic performance. Major categories of promising electrocatalysts are then reviewed, including noble-metal-based materials, non-noble-metal single-atom catalysts, non-noble-metal compounds, and metal-free carbon-based materials. The innovative development of electrochemical devices and in situ/on-site application of electrogenerated H2O2 are also highlighted to bridge the gap between laboratory-scale fundamental research and practically relevant H2O2 electrosynthesis. Finally, critical perspectives on present challenges and promising opportunities for future research are provided.