Polyoxometalates-doped TiO2/Ag hybrid heterojunction: removal of multiple pollutants and mechanism investigation

Abstract

Photocatalysis is considered to be an effective and sustainable way to purify a variety of refractory pollutants. However, the construction of a versatile efficient photocatalyst is still an arduous challenge. Herein, a series of mesoporous TiO₂-doped with polyoxometalates [PMo₁₀V₂O₄₀]⁵⁻ (PMV) and loaded with Ag nanoparticle composite photocatalysts PMV-TiO₂/Ag_x (x represented the mass of AgNO₃) are presented. In this composite, polyoxoanions PMV are uniformly dispersed in mesoporous TiO₂, which not only acts as a dopant to effectively expand the visible light absorption of TiO₂ but also acts as a component to form the S-scheme heterojunction with modified TiO₂ to promote the separation of the photogenerated carrier. Furthermore, the Schottky junction between Ag nanoparticles and PMV-doped TiO₂ further enhances its carrier separation. The synergistic effect of the above factors endows PMV-TiO₂/Ag_x with excellent photocatalytic activity. PMV-TiO₂/Ag_0.1 can completely degrade 10 ppm of 2,4-dichlorophenol in 180 minutes (λ ≥ 420 nm), which is about 8.3 times higher than that of traditional TiO₂. In addition, PMV-TiO₂/Ag_0.1 also exhibits ultrahigh photocatalytic performance and durability for the photocatalytic removal of 2,4-difluorophenol, 2,4-dibromophenol, hexafluorobisphenol A, tetracycline, K₂Cr₂O₇, methyl orange, which is an excellent photocatalyst with high efficiency and universal application.