Analysis of photocatalytic characteristics and mechanical properties of TiO₂ thin films

Using radio frequency reactive sputtering technology, the Ar/N₂/O₂ gas flow ratio is 45/45/10, and TiO₂ thin films are prepared using TiO₂ ceramic targets. TiO₂ samples were subjected to different heat treatment methods, such as air cooling in the atmosphere, atmospheric annealing, and vacuum annealing at temperatures of 250 °C, 350 °C, and 450 °C, respectively. The impact of post-thermal treatment on the structure, morphology, band gap (Eg) values, photocatalytic activities, and mechanical properties of TiO₂ films was examined. The X-ray diffraction pattern shows that the TiO₂ film has an amorphous structure. The as-deposited TiO₂ films’ SEM surface morphology is relatively smooth, possibly due to their poor crystallinity. The SEM images show an apparent increase in morphological grain-like features when the thermal annealing temperature increases from 250 to 450 °C. Increasing the heat treatment temperature will reduce the optical Eg value and exhibit excellent photocatalytic characteristics. Heat treatment, which improves the morphological features of the film, may enhance the film’s mechanical properties. The elastic recovery and hardness values ​​slightly increase with a higher nanoindentation load. Experimentally recorded nanoindentations agree well with elastic recovery values ​​from finite element simulations.