Microstructure and superhydrophilicity of anodic TiO2 films on pure titanium

The superhydrophilicity of TiO2 prepared by anodization of pure titanium was investigated and the underlying mechanism was explored. The water contact angle of the as-anodized oxide decreases with the conversion voltage and ultraviolet (UV) light illumination, whereas the annealed oxide exhibits further low contact angles regardless of the conversion voltage and UV illumination. The O 1s X-ray photoelectron spectroscopy spectra of the oxides have a shoulder peak due to adsorption of hydroxyl groups and the intensity of the peak increases with annealing and UV illumination; these observations suggest that the interaction between the surface of the oxide and the hydroxyl groups is enhanced.