Recent advances in electrochemical 2e oxygen reduction reaction for on-site hydrogen peroxide production and beyond

The electroproduction of H₂O₂ through 2e oxygen reduction reaction (ORR) as an alternative strategy for the conventional anthraquinone process is highly energy-efficient and environment-friendly. Different kinds of electrocatalysts with high selectivity, activity, and stability have been recently reported, and are an essential part of the whole electroproduction process of H₂O₂. In this review, we expound the ORR mechanism and introduce some methods to screen out potential electrocatalysts through theoretical calculations and experimental verifications. In addition, recent advances in reactor design for large-scale on-site production of H₂O₂ and integrated systems for electricity-H₂O₂ co-generation are mentioned. With ideal electrocatalysts and rational reactor design, different concentrations of H₂O₂ can be obtained depending on the practical applications. Utilizing the solar or chemical energy, it can promote energy efficiency and sustainability of the process. Finally, we make a brief conclusion about recent developments in electrocatalysts, device design, as well as integrated systems, and give an outlook for future research challenges, which are meaningful for advancing the electrochemical on-site production of H₂O₂via 2e ORR to the marketplace.