Synthesis and photocatalytic properties of ultra-smooth TiO2 thin films with superhydrophilicity

Abstract

Functional TiO2 films were fabricated on glass substrates by using modified dip coating method. The properties of the films including crystal structures, thickness, surface morphology and optical properties were studied. The film coated once possessed an ultra-smooth surface with a root mean square (RMS) roughness of 2.6 ± 0.7 nm, which was attributed to the effect of N2 flow during the formation of film. The TiO2 films exhibited superhydrophilicity without UV illumination and the superhydrophilic performance was enhanced with the increase of film thickness. Tests on degradation of dyes under UV illumination indicated that the annealing temperature and thickness of the TiO2 films accounted for their photocatalytic performance. An increase of annealing temperature led to a decrease of the amount of defects and the recombination rate of electron-hole pairs. Because of change of film thickness, light absorption and amount of defects of the TiO2 films influenced photocatalytic performance simultaneously.