Hydrophilicity and formation mechanism of large-pore mesoporous TiO2 thin films with tunable pore diameters

Using n-butanol released in situ as the cosurfactant, transparent large-pore mesoporous nanocrystalline anatase (meso-nc-TiO2) thin films with narrow pore size distribution have been successfully synthesized in a Ti(OBun)(4)-P123-EtOH-HCl system. Furthermore, the mesopore size can be easily controlled in the range of 8.3-14.0 nm through adjusting the quantities of Ti(OBun)(4), corresponding to the amount of n-butanol released in situ. X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption were used to investigate the relationship between the amount of Ti(OBun)(4) and the structural parameters of the obtained meso-nc-TiO2 thin films. A reasonable mechanism is also proposed here to explain the formation of large-pore mesoporous TiO2 with tunable pore diameters. The hydrophilicity of our obtained films was evaluated by water contact angle measurement in air. It was found that, in the absence of ultraviolet (UV) illumination, the presented transparent large-pore meso-nc-TiO2 thin films exhibit high hydrophilicity.