Self-Assembly Hydrothermal Synthesis of Silverton-Type Polyoxometalate-Based Photocatalysts for Enhanced Degradation.

Abstract

The synthesis of some complex polyoxometalates (POMs) is critical to develop potential photocatalysts with high catalytic activity and selectivity. Here, we address this challenge by a hydrothermal self-assembly route to obtain a novel POM-based Co4W6O21(OH)2·4H2O with a hierarchical microsphere structure. The Co4W6O21(OH)2·4H2O crystallizes in the cubic space group Im3̅ with cell parameters: a = b = c = 12.878 Å, α = β = γ = 90°, and Z = 4. The structure is further characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectra. After depositing Ag2O nanoparticles on the 3D Co4W6O21(OH)2·4H2O microsphere by photochemical synthesis, the Co4W6O21(OH)2·4H2O/Ag2O heterojunction presents enhanced photocatalytic activity for RhB compared with P25 and pristine Ag2O. Moreover, we confirm the key role of holes for the Co4W6O21(OH)2·4H2O/Ag2O and put forward a possible mechanism for the photocatalytic degradation reaction.