Enhanced Visible Light Photocatalytic Activity of Ag and Zn Doped and Codoped TiO2 Nanoparticles

In the present study, this report discusses the preparation and photocatalytic properties of pure, Ag and Zn doped and Ag–Zn codoped TiO2 nanoparticles by sol–gel method. The powder X-ray diffraction study showed that crystallite size of doped and codoped TiO2 nanoparticles was decreased compared with pure TiO2. The decreased particles size was confirmed by high resolution transmission electron microscope and the particle size was in the range of 7–19 nm. The influence of codopant on the morphology of Ag–Zn codoped TiO2 was clearly observed in the field electron scanning electron microscope. From the UV–Vis diffuse reflectance spectrum, it was observed that the doping and codoping of Ag and Zn reduce the energy gap of TiO2. The reduced emission intensity of doped and codoped TiO2 in the photoluminescence spectrum suggests that the Ag and Zn lower the recombination of electron–hole pairs. The increase of Zn dopant level (0.2, 0.4 and 0.6 mol%) at 1 mol% of Ag in the codoped TiO2 further reduces the emission intensity. The 0.6 mol% of Zn at 1 mol% of Ag in the codoped TiO2 shows higher photocatalytic degradation ability against Reactive Yellow 145 under visible light compared with all other nanoparticles.