Photocatalytic properties of annealed TiO2 films with controlled structure fabricated using oxygen-ion-assisted reactive evaporation with glancing angle deposition technique

Abstract

Titanium dioxide (TiO2) has been an attractive material for applications such as in photocatalytic reactions, water purification, and cancer treatment. However, issues with the deposition methods have affected the performance of TiO2 films. Herein, we have developed a method to deposit TiO2 at room temperature using oxygen-ion-assisted reactive evaporation combined with glancing angle deposition. Furthermore, we investigated the effect of the incident angle and air annealing temperature range of 450–650 °C on the crystallinity, morphology, and photocatalytic properties of the deposited films. The physical microstructures were investigated via the θ–2θ x-ray diffraction method and field-emission scanning electron microscopy. The hydrophilicity was evaluated by measuring the contact angle of pure water on the film surface. The organic decomposition characteristics were evaluated by following decomposition of methylene blue under ultraviolet light irradiation. We found that as the annealing temperature increased, the grain size increased. A highly porous structure was formed at a higher incident angle of 80°, increasing the effective surface area of the TiO2 films. Furthermore, good organic decomposition capability was achieved using the TiO2 films deposited at the incident angle of 80° and annealed at 650 °C. We have demonstrated a method to deposit TiO2 films with improved properties, such as morphology, hydrophilicity, and specific surface area, which led to the improvement of the photocatalytic characteristics.