Photocatalytic activity of V5+, Mo6+ and Th4+ doped polycrystalline TiO2 for the degradation of chlorpyrifos under UV/solar light

TiO2 photocatalysts were prepared by doping transition metal ions like V5+, Mo6+and an inner transition metal Th4+ in the concentration range of 0.02–0.1% and were characterized by various analytical techniques. The photocatalytic activities of these catalysts were studied for the mineralization of chlorpyrifos (CP) as a probe molecule. X-ray diffraction results showed only anatase phase irrespective of nature, oxidation state and concentration of these dopants. The photocatalytic activity of undoped TiO2 showed a better activity under UV light compared to doped catalysts. Under solar light illumination, the Th4+ (0.06%)–TiO2 showed highest activity for the mineralization of CP. This was attributed to the prolonged separation of photogenerated electron–hole pairs, high specific surface area of the catalyst and high concentration of surface adsorbed water/hydroxyl groups. Further large shift in the absorption band (460 and 482 nm) due to the creation of mid band gap states by Th4+ dopant and also by its small crystallite size additionally contributes to the enhancement of the degradation process. The degradation pathway was followed by UV–vis spectroscopic and GC–MS analysis.

Graphical abstractTiO2 was doped with metal ions like V5+, Mo6+ and Th4+ in the concentration range from 0.02 to 0.1 at% and were characterized. XRD results showed that doped catalysts had only anatase phase irrespective of their nature, oxidation state, ionic size and concentraiton of these dopants. These photocatalysts were used for the mineralization of chlorpyrifas pesticide.Figure optionsDownload full-size imageDownload as PowerPoint slide