Effect of the local structure of Ti-oxide species on the photocatalytic reactivity and photo-induced super-hydrophilic properties of Ti/Si and Ti/B binary oxide thin films

From the results of various spectroscopic investigations of Ti-oxide-based binary oxides, it was found that tetrahedrally coordinated Ti-oxide species are formed in the thin films of Ti/Si binary oxides with low TiO2 content, while octahedrally coordinated TiO2 nano-particles are formed in the Ti/B binary oxide thin films, reflecting the effect of the crystalline structures of the host SiO2 or B2O3 on the local structure of the guest Ti-oxide species, respectively. The photocatalytic reactivity of the TiO2 thin films was found to be remarkably enhanced by the dispersion of the Ti-oxide moiety into both the SiO2 and B2O3 matrices, whereas the photo-induced super-hydrophilic properties of the TiO2 thin films were enhanced only by a combination or mixing of the Ti-oxide moiety with B2O3.