The synthesis of bayberry-like mesoporous TiO2 microspheres by a kinetics-controlled method and their hydrophilic films

A superhydrophilic film without UV irradiation consisting of bayberry-like mesoporous TiO2 microspheres was prepared via a simple hydrothermal method combined with the spin-coating method. The crystal structure and surface morphology of the mesoporous TiO2 microspheres could be adjusted by controlling the reaction kinetics of hydrolysis and condensation of titanium tetrachloride in water/urea aqueous mixtures. The results showed that the surface morphology of TiO2 changed from "papilla-like", "rough" to "smooth" and the crystal structure also changed from rutile to anatase when the amount of urea used ranged from 0 to 2 g. The film consisting of the bayberry-like TiO2-1.68 sample had a water contact angle of 2 degrees without UV irradiation, and its superhydrophilic property could be ascribed to the cooperative effect between the surface roughness and high density of surface hydroxyl groups. This demonstrates that nanoflower mesoporous TiO2 microspheres with a rough surface can be obtained via the kinetics-controlled method, which can provide a new method for designing mesoporous TiO2 with different structures, surface morphologies and multi-functionalities.