Microstructure characterization and photocatalytic activity of mesoporous TiO2 films with ultrafine anatase nanocrystallites

A series of mesoporous TiO2 films on borosilicate glass with ultrafine anatase nanocrystallites were successfully synthesized using a non-acidic sol gel preparation route, which involves the use of nonionic surfactant Tween 20 as template through a self assembly pathway. The microstructure of these TiO2 films was characterized by XRD, SEM, HR-TEM, UV–Vis spectroscopy, and N2 adsorption–desorption isotherm analysis. Their photocatalytic activities were investigated by using creatinine as a model organic contaminate in water. It was found that all mesoporous TiO2 films prepared with Tween 20 exhibited a partially ordered mesoporous structure. The photocatalytic activity of the TiO2 films could be remarkably improved by increasing Tween 20 loading in the sol at the range of 50% (v/v), which yielded large amount of catalyst (anatase) on the glass support and enhanced specific surface area. The optimum Tween 20 loading was 50% (v/v) in the sol, above which good adhesion between TiO2 films and borosilicate glass could not be maintained. The final TiO2 film (Tween 20: final sol = 50%,v/v) exhibits high BET surface area (∼ 120 m2/g) and pore volume (0.1554 cm3/g), ultrafine anatase nanocrystallinity (7 nm), uniform and crack free surface morphology, and improved photocatalytic activity.