Utilizing Carbonaceous Catalysts for H2O2 Electrosynthesis via the Two-Electron Oxygen Reduction Reaction

The electrochemical two-electron oxygen reduction reaction (2e- ORR) offers a promising pathway for decentralized hydrogen peroxide (H2O2) production, providing an attractive alternative to the conventional anthraquinone process. The emergence of metal-free carbonaceous catalysts for efficient H2O2 electrosynthesis is gaining momentum, with the potential to drive the development of novel industrial applications. This review aims to provide a comprehensive guide to the use of carbon-based catalysts in the selective electroreduction of O2 to H2O2. It begins by discussing the fundamental aspects of the electrocatalytic 2e- ORR, including overviews of reaction mechanisms, theoretical insights, and evaluation methodologies. The review then delves into potential active sites and the associated engineering strategies for carbon-based electrocatalysts, such as defect engineering, heteroatom doping, interactions with metal species, and single-atom modifications. Furthermore, strategies extending beyond active site optimization, along with advancements in electrolysis reactor design and potential application areas, are discussed to bridge the gap between laboratory-scale research and practical H2O2 electrosynthesis. The paper concludes by assessing current challenges and outlining research directions, emphasizing the efforts needed to enhance the feasibility and scalability of H2O2 electrosynthesis.