Carbon electrodes for the electrocatalytic synthesis of hydrogen peroxide: A review

Electrocatalytic oxygen reduction by a 2e⁻ pathway enables the instantaneous synthesis of H₂O₂, a process that is far superior to the conventional anthraquinone process. In recent years, the electrocatalytic synthesis of H₂O₂ using carbon electrodes has attracted more and more attention because of its excellent catalytic performance and superior stability. The relationship between material modification, wettability and the rate of H₂O₂ synthesis and service life is considered together with the three-phase interface. The structure of the carbon electrodes and the principles of electrocatalytic H₂O₂ synthesis are first introduced, and four major catalysts are reviewed, namely, monolithic carbon materials, metal-free catalysts, noble metal catalysts and non-precious metal catalysts. The effects of the metal anode and the electrolyte on the three-phase interface are described. The relationship between carbon electrode wettability and the three-phase interface is described, pointing out that modification focusing on improving the selectivity of the 2e⁻ pathway can also impact electrode wettability. In addition, the relationship between the design of the components in the electrochemical system and their effect on the efficiency of H₂O₂ synthesis is discussed for carbon electrodes. Finally, we present our analysis of the current problems in the electrocatalytic synthesis of H₂O₂ for carbon electrodes and future research directions.