Visible light photocatalytic degradation of organic dyes using W-modified TiO₂/SiO₂ catalyst

Abstract

In the present study, the synthesis of W-modified TiO₂/SiO₂ composite and its catalytic activity in the visible light region is demonstrated. The W-modified TiO₂/SiO₂: composite was obtained from the hydrolysis of a mixture containing titanium (IV) oxysulfate, ammonium metatungstate, and SiO₂, powder in an alkaline medium. The obtained materials were characterized by using X-ray diffraction (XRD), Fourier transformation-infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray elemental mapping observation, nitrogen adsorption/desorption isotherms, photoluminescence spectra (PL), and ultraviolet visible diffusive reflectance spectroscopy (UV-Vis DRS). In this material, W-modified TiO₂ nanoparticles of about 3-5 nm were highly dispersed on the silica network. Both W-modified TiO₂ and W-modified TiO₂, decorated on the SiO₂ substrate significantly promoted the visible light absorption of the material. The photocatalytic activity of the prepared catalyst was assessed through the photodegradation of Methylene blue, Rhodamine-B, Methyl orange, and Congo red dyes under visible light illumination. It was found that the kinetic and equilibrium data of the photocatalytic process fitted the modified Langmuir-Hinshelwood model well. Recyclable studies have shown that the catalyst still retained its original activity after the third cycle.