Synthesis, characterization and photocatalytic properties of nanosized Bi2WO6, PbWO4 and ZnWO4 catalysts

Nanosized Bi2WO6, PbWO4 and ZnWO4 photocatalysts were synthesized by a mild hydrothermal crystallization process. The physical and photophysical properties of the catalysts were characterized by X-ray diffractometry, Brunauer–Emmet–Teller surface area and porosity measurements, transmission electron microscopy, Raman spectra, and diffused reflectance spectroscopy. The rhodamine-B photodegradation in aqueous medium was employed as a probe reaction to test the photoactivities of the as-prepared samples under four irradiation wavelengths. Bi2WO6 not only presented the photocatalytic activity in the wide spectral scope, including UV and visible light but also exhibited the strong photosensitized capability to transform RhB under visible light irradiation (λ > 490 nm). ZnWO4 only displayed relatively high photoactivity under UV irradiation. However, PbWO4 showed poor photoactivity under any light irradiation. On the basis of the calculated density functional theory (DFT), the photocatalytic mechanisms were discussed.