Synthesis and characterization of Sn doped TiO2 photocatalysts: Effect of Sn concentration on the textural properties and on the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

Abstract

"TiO 2 and Sn-doped TiO 2 materials were prepared by sol–gel method using titanium and tin alkoxides at different Sn concentration (0.1 mol%, 0.5 mol%, 1 mol%, 3 mol% and 5 mol%). Samples were characterized by thermo gravimetric analyzer with differential scanning calorimeter (TGA–DSC), X-ray Rietveld refine- ment, N 2 adsorption (BET), transmission electron microscopy (TEM), UV–vis spectroscopies technology and Raman spectroscopy. Only anatase phase was observed in pure TiO 2 , whereas anatase and brookite were obtained in Sn-doped TiO 2 samples. Sn dopant acts as a promoter in phase transformation of TiO 2 . The Rietveld refinements method was used to determine the relative weight of anatase and brookite, and crystallite size as a function of Sn concentration after calcination of samples at 673 K. It was also demon- strated the incorporation of Sn 4+ into the anatase TiO 2 structure. Sn 4+ inhibits the growth of TiO 2 crystal- lite size, which leads to an increase of the specific surface area of TiO 2 . From XRD analysis, the solid solution limit of Sn 4+ into TiO 2 is 5 mol% Sn. The photocatalytic activity on Sn 4+ doped TiO 2 was deter- mined for the 2,4-dichlorophenoxyacetic acid reaction. The maximum in activity was attributed to the coexistence of anatase and brookite phases in the appropriate ratio and crystallite size."