Synthesis, characterization and photocatalytic application of ZnWO_4/ZrO_2 nanocomposite towards degradation of methyl orange dye

Visible light active ZnWO_4/ZrO_2 nanocomposite was prepared via hydrothermal method. The nanocomposite was characterized by UVvisible diffuse reflectance spectroscopy (UVvisDRS), Fourier transform infrared spectroscopy (FTIR), Xray diffraction (XRD), Scanning Electron microscopy (SEM), energy dispersive Xray spectroscopy (EDX) and transmission electron microscopy (TEM) techniques. The XRD results showed that average particle size of ZrO_2, ZnWO_4 and ZnWO_4/ZrO_2 were found to be 29.20 nm, 23.78 nm and 20.14 nm respectively and the phase structure for ZrO_2 and ZnWO_4 in the composite was Rhombohedral and Monoclinic respectively. The UV–vis absorption spectra of the ZnWO_4/ZrO_2 nanocomposite noticeably shifted to the visible light region compared to that of the ZrO_2. The prepared photocatalyst were composed of plate and spongy sphere with little agglomeration was seen from SEM result. The photocatalytic activities of the prepared nanocomposite was evaluated for the degradation of methyl orange (MO) under visible light irradiations. The effect of operational parameters such as initial dye concentration, pH, catalyst concentration and irradiation time have been investigated in detail. The photocatalytic degradation efficiency of ZnWO_4/ZrO_2, ZnWO_4 and ZrO_2 for 95%, 72% and 60 % respevtively. The high photocatalytic activity can be attributed to stronger absorption in the visible light region, a greater specific surface area, smaller crystal sizes, more surface OH groups, and to the effect of ZnWO_4 doping, which resulted in a lower band gap energy.