Synergistic Enhancement of Photocatalytic H2O2 Production by Spatially Separated Redox Sites for Water Disinfection.

Photocatalytic two-electron reduction of O2 in pure water is a promising method to produce H2O2, an environmentally friendly oxidant and clean energy carrier. However, the sluggish redox sites associated with two-electron O2 reduction and two-electron or four-electron H2O oxidation constrain the efficiency of H2O2 production. Herein, we report on the rational design of a type of Z-scheme hollow heterostructured sphere, where Zn2In2S5 with sulfur vacancies is uniformly integrated onto boron-doped hollow carbon nitride spheres (hBCN@ZIS-SV). This type of structure features spatially separated redox sites, which have been found to synergistically enhance the capture and utilization of photogenerated electrons and holes, thereby facilitating the efficient reduction of O2 into H2O2. The optimized hBCN@ZIS-SV exhibits a notable H2O2 production rate of approximately 700 μmol g-1 h-1, with an apparent quantum efficiency of 3.61% at 420 nm and a solar-to-chemical conversion efficiency of 0.14% in pure water. Moreover, the photocatalytic H2O2 production using hBCN@ZIS-SV, combined with the Fenton reaction, demonstrates an outstanding efficiency in water disinfection. Furthermore, we have also developed floating photocatalytic films composed of hBCN@ZIS-SV, which paves the way for future practical applications in real water systems.