Annealing temperature effects on sol–gel nanostructured mesoporous TiO2/SiO2 and its photocatalytic activity

Mesoporous TiO2/SiO2 (5 wt% TiO2) was synthesized by the sol–gel method and thermally treated up to 1273 K. The materials obtained were characterized by N2 adsorption/desorption isotherms, XRD, TEM, Raman and UV–vis diffuse reflectance spectroscopies. The results indicate the presence of thermally stable anatase TiO2 nanoparticles (∼20 nm) highly dispersed in the SiO2 matrix, with no evidence of particle growth for materials treated up to 1073 K. Important features related to the number of structural defects and short-distance ordering of TiO2 nanoparticles were found and they have a direct relationship with the photocatalytic performance of the materials. Higher photocatalytic activity toward methylene blue decolourisation was observed for solids annealed at higher temperatures.