Photocatalytic activity of TiO₂ films deposited by reactive multi pulse HiPIMS at different substrate temperature values

摘要

Reactive high power impulse magnetron sputtering (HiPIMS) operated in multi-pulse mode was used to grow titanium dioxide (TiO_(2)) thin films on quartz at different substrate temperature values. The films were characterized by X-Ray diffraction, atomic force microscopy, Raman spectroscopy and UV-Vis transmission spectroscopy techniques to investigate the influence of substrate temperature on the microstructure and optical properties of the deposited thin films. In particular, the substrate temperature affected the crystallinity, energy band gap, hydrofilicity induced by UV light irradiation and photocatalytic activity of the deposited films. The photocatalytic activity was evaluated by experiments of degradation under visible light irradiation of the methylene blue molecules in water. It is shown that the photocatalytic activity gradually increases with the value of the substrate temperature used in depositions. By increase of the substrate temperature, the structure of the deposited films changed from amorphous to crystalline anatase phase, while the optical band gap gradually decrease from 3.2 eV to 2.8 eV. These changes in microstructure and optical properties are considered as the main causes of the significant improvement by substrate heating of the visible light photocatalytic activity of the TiO_(2) thin films.