Modifications of pure and Ag doped TiO2 by pre-sulphated and calcination temperature treatments

Pre-sulphated pure and Ag doped TiO₂ photocatalysts were prepared by a modified low cost liquid impregnation method followed by acid (H₂SO₄) treatments. Surface and morphological characterizations of the prepared samples as well as their photocatalytic activity towards methyl orange (MO) were studied. The influence of sulphate pretreatment on the surface of pure TiO₂, the dispersion of deposit metals and the particle size were analyzed for the samples exposed to different calcination temperature (i.e. 500, 600 and 700 °C) treatments. The physical characterizations of the photocatalysts were investigated using diffused reflectance spectroscopy (UV–Vis DRS), XRD, BET, TEM, SEM and EDX analyses. The Kubelka–Munk function was used to determine the band gap energy for all prepared samples, whereby the band gap energy of pre-sulphated 1% Ag doped TiO₂ was found to be reduced to 2.95 eV. Photocatalytic activity towards the degradation of MO was found to be enhanced between 30 and 37% for the 1% Ag/TiO₂-S compared to the undoped TiO₂-S samples. The pre-sulphated sample of 1% Ag/TiO₂-S calcined at 700 °C showed up to 80% degradation of MO under normal compact fluorescent light.