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 HO. However, despite great efforts to optimize photocatalyst activity, the formation rate has been largely limited by the deficient accessibility of the photocatalysts to sufficient O in water. Here we boost the reaction by reporting an air-liquid-solid triphase photocatalytic system for efficient HO generation. The triphase system allows reactant O to reach the reaction interface directly from the ambient atmosphere, greatly increasing the interface O concentration, which in turn simultaneously enhanced the kinetics of formation constant and suppressed the unwanted electron-hole recombination and the kinetics of HO decomposition reaction. Compared with a conventional liquid-solid diphase reaction system, the triphase system enables an increase in HO 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 HO generation.