The photocatalytic oxidation of water with gaseous oxygen is environmentally benign for the synthesis of hydrogen peroxide (H2O2), but it is currently constrained by the inadequate supply of gaseous oxygen at the catalyst surface in a solid-liquid-gas triple-phase reaction system. Herein, we address this challenge by employing the zeolite encapsulated catalysts that efficiently enrich gaseous oxygen and accelerate the H2O2 synthesis in in aqueous conditions. We focus on the classical titania photocatalyst, encapsulating it within siliceous MFI zeolite crystals. This encapsulation results in a significant enhancement in H2O2 synthesis efficiency, achieving a yield that is ten times greater than that with unencapsulated TiO2. Mechanism study reveals that gaseous oxygen is notably concentrated within the microporous structure of the zeolite under aqueous conditions, thereby facilitating its interaction with the titania surface at the liquid-solid interface. In addition, the H2O2 product could swiftly transfer through the micropores, thereby reducing the side reaction of decomposition. This design provides an alternative pathway to address the poor gas solubility of gaseous reactants in water, and paves the way for advancements in various other photocatalytic processes.
Keywords: Hydrogen Peroxide; Zeolite; interfacial gas availability; oxygen reduction; photocatalysis.
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