Influence of oxygen partial pressure on wettability and photocatalytic properties of TiO2 films grown by RF magnetron sputtering
Titanium oxide (TiO2) thin films were deposited at 400°C by radio frequency (RF) magnetron sputtering on glass substrates. The effect of the oxygen partial pressure on the structural, morphological, hydrophilic and photocatalytic properties was studied. The structure was investigated by X-ray diffraction (XRD) and the morphology by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The photocatalytic activity was evaluated by degradation of pre-adsorbed methylene blue (MB) under visible light whereas the hydrophilicity was assessed by contact angle measurements. Results show a unique way to tune the phase composition with the aim of optimizing the reactivity and wettability of titania thin films.
The optimization of high-performance TiO2 thin films represents an ever growing research field that follows the increasing demand in numerous area like solar cells (1), photocatalytic environmental remediation (2, 3), gas sensing (4) and self-cleaning glasses (5). Many are the properties to be tailored to achieve an outstanding performance in the aforementioned applications: the film should ensure superior photocatalytic activity and UV-induced wettability as well as enhanced transparency and mechanical performance in terms of hardness and adhesion to the substrate. Among the various techniques used for the fabrication of such coatings, sputtering has aroused great attention because, in addition to being applicable to large area-deposition at industrial scale, it is able to meet all the mentioned requirements, with the possibility of fine-tuning the film features by adjusting a number of deposition parameters like power supplied, gas pressure, distance between substrate and target, substrate temperature and partial pressure of reactive gases (6, 7).
Numerous studies on sputtered TiO2 thin films have reported a ...