Few-layered tungsten selenide as a co-catalyst for visible-light-driven photocatalytic production of hydrogen peroxide for bacterial inactivation

Abstract

Sustainable and “green” technologies for hydrogen peroxide (H₂O₂) production have aroused increasing interest, yet challenges prevail in production of H₂O₂ for environmental applications. In this study, tungsten selenide (WSe₂) with a few-layered microstructure was used as a new co-catalyst to synthesize H₂O₂ under visible light irradiation. The ultrathin WSe₂ nanosheets were anchored onto a g-C₃N₄ surface by in situ growth solvothermal methods. The as-prepared WSe₂/g-C₃N₄ showed remarkably enhanced H₂O₂ production efficiency without organic electron donors, which was 11.8 times higher than that of pristine g-C₃N₄. H₂O₂ was generated via O₂ reduction mediated by photogenerated e⁻, and dissolved O₂ could be generated by water oxidation and in situ used to produce H₂O₂ under anaerobic conditions. The introduction of WSe₂ not only promoted visible light absorption, but also facilitated the charge transfer efficiency by forming a Z-scheme rather than a type II heterojunction. The photogenerated e⁻ was enriched onto WSe₂, leading to the high H₂O₂ production activity. Moreover, the in situ generated H₂O₂ could be directly used for pathogenic bacteria inactivation through Fenton reactions without external H₂O₂ addition. This work is expected to open an avenue for developing novel photocatalysts towards sustainable H₂O₂ production for water disinfection and related environmental applications.