Rational Designs of Two-Electron Oxygen-Reduction Electrocatalysts for H2O2 Production and Its In-Situ Integration with Oxidation Reaction in Green Chemical Processes

Abstract

Hydrogen peroxide (H2O2) is a vital chemical widely utilized across diverse fields, including disinfection, paper manufacturing, bleaching, and pollution control. However, the industrial production of H2O2 primarily relies on the conventional anthraquinone process with high energy consumption, large carbon emissions, and costly transportation. The electrochemical two-electron (2e-) oxygen reduction reaction (ORR) for H2O2 production driven by renewable energy exhibits the advantages of cheap and readily available raw materials, mild reaction conditions, and facilitation of decentralized production, effectively overcoming the shortcomings of the anthraquinone method. Moreover, the 2e- ORR can be further in-situ coupled with other chemical reactions. These innovative coupled systems integrate H2O2 production with its direct utilization, enhancing H2O2 utilization efficiency while significantly lowering transportation costs. Moreover, the special coupled process can promote the formation of a local high-concentration H2O2 interface and highly active oxidative species, enabling efficient, eco-friendly, and low-cost pollutant degradation as well as the synthesis of high-value-added chemicals. But, the ORR typically exhibits two reaction pathways (2e- and 4e- reduction processes), with the corresponding products being H2O2 and H2O, respectively. This poses significant challenges in simultaneously increasing the catalytic activity and the selectivity of H2O2. A deep understanding of the mechanisms underlying enhanced ORR catalytic performance is essential for designing high-performance catalysts and improving the efficiency of electrochemical H2O2 synthesis. Furthermore, it is pivotal for advancing the development of innovative coupled systems aimed at sustainable chemical production. In this review, we provide a thorough summary of the electrocatalytic mechanism of the ORR, recent advancements in the ORR catalysts, application of advanced in-situ characterization methods, innovative coupled application strategies for the 2e- ORR, and future perspectives on the electrochemical H2O2 synthesis coupled with oxidation reaction in green chemical processes.