Effect of solvent volume on the properties of ZnWO4 nanoparticles and their photocatalytic activity for the degradation of cationic dye

Abstract

In this paper, we report the photocatalytic degradation performance of zinc tungstate (ZnWO4) nanoparticles prepared by co-precipitation technique by the effect of increasing the volume of solvent (30 ml−90 ml). The well defined x-ray diffraction peaks confirmed the formation of pure monoclinic phase zinc tungstate with wolframite structure. The vibrational bands corresponding to W-O bond stretching and bending vibrations in WO6 group are occurred at 714 and 615 cm−1, which indicates the good crystallinity and relatively low concentration of defects in ZnWO4. The photoluminescence emission peak observed at 380 nm region is due to the electronic transition of Zn-WO4. The optical energy band gap decreases (3.19 eV−3.16 eV) as the volume of the solvent increases (30–90 ml) which may be due to the reducing interaction of metal–oxygen orbital. The photocatalytic activity of wolframite ZnWO4 nanoparticles was investigated by the decomposition of methylene blue (MB) dye pollutant under ultra-violet (UV) lamp (254 nm) irradiation at room temperature. The highest dye removal efficiency of 81% was noticed for ZnWO4 nanoparticles synthesized with 30 ml volume of solvent, which may be due to the presence of more active species and nanopores on the surface.