Efficient Hydrogen Peroxide Generation Utilizing Photocatalytic Oxygen Reduction at a Triphase Interface

Photocatalytic oxygen reduction has garnered attention as an emerging alternative to traditional anthraquinone oxidation process to synthesize H₂O₂. However, despite great efforts to optimize photocatalyst activity, the formation rate has been largely limited by the deficient accessibility of the photocatalysts to sufficient O₂ in water. Here we boost the reaction by reporting an air-liquid-solid triphase photocatalytic system for efficient H₂O₂ generation. The triphase system allows reactant O₂ to reach the reaction interface directly from the ambient atmosphere, greatly increasing the interface O₂ concentration, which in turn simultaneously enhanced the kinetics of formation constant and suppressed the unwanted electron-hole recombination and the kinetics of H₂O₂ decomposition reaction. Compared with a conventional liquid-solid diphase reaction system, the triphase system enables an increase in H₂O₂ formation by a factor of 44. The triphase system is generally applicable to fundamentally understand and maximize the kinetics of semiconductor-based photocatalytic oxygen reduction for H₂O₂ generation.