Highly transparent, superhydrophilic and high-temperature stable anatase phase TiO2

Abstract

Stable anatase phase of TiO2 above 700 °C plays a very important role in the fields of photocatalysis, antibacterial, self-cleaning and solar cells etc. However, the stabilization of the anatase phase of TiO2 at higher temperatures has been very challenging so far. Here, we report a glancing angle deposition (GLAD) employing e-beam evaporation to fabricate slanted nanorods, vertical nanorods, and zig-zag nanorods of TiO2, which show the stabilization of the anatase phase up to 1000 °C. The amorphous nature of the substrate and least oxygen vacancy in the TiO2 are found to be the major cause for the thermal stabilization of the anatase phase. All annealed samples were found to be superhydrophilic when measured immediately after annealing, while the dark storage transforms the samples to hydrophilic. Nevertheless, UV exposure for 10 min reverted them to superhydrophilic. FTIR studies were performed on the samples to understand the role of surface hydrocarbons in the transition from hydrophobic to hydrophilic states. The samples show a transmittance ∼90% in the visible spectrum. The simultaneous existence of a highly transparent, superhydorphilic and high temperature stable anatase TiO2 can give a boost to several fields e.g., smart windows/doors, self-cleaning coatings, etc.