Preparation and characterization of UV-light-driven Pd/ZnWO4 nanocomposites for enhanced efficiency in photocatalytic degradation of rhodamine B

UV-light-driven ZnWO4 photocatalysts loaded with different weight contents of Pd were prepared by a sonochemical-assisted deposition method for the degradation of rhodamine B (RhB) under UV light irradiation. Phase, oxidation state, composition, surface area and morphology of ZnWO4 and Pd/ZnWO4 were analyzed by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy and mass spectroscopy. Upon loading with fine dispersed Pd nanoparticles with a size of 8–10 nm on the surface of ZnWO4 nanorods, heterojunctions of metallic Pd nanoparticles–ZnWO4 nanorods were clearly detected. The reaction rate constant for RhB degradation was increased from 1.87x10–3 min–1 for ZnWO4 to 0.0246 min–1 for 5% Pd/ZnWO4 nanocomposites within 150 min under UV light irradiation because the Pd nanoparticles–ZnWO4 nanorods Schottky barriers played the role in promoting charge separation of electron–hole pairs and preventing the recombination of charge carrier pairs. The trapping experiment showed that h+ and ●OH were the main active species for the photocatalytic reaction of RhB under UV light irradiation. Research Highlights • Pd/ZnWO4 nanocomposites were prepared by sonochemical-assisted deposition method. • The nanocomposites played the role in degrading rhodamine B under UV radiation. • The promising material used for wastewater treatment.