Praparation And Study On Photocatalytic Properties Of TiO₂: W Thin Films

As the ideal material of photocatalysis, titanium dioxide thin films, which have now been got an extensive research, are applied in environmental protection widely. Titanium dioxide is a semi-conductor with wide band gap, and its photocatalysis operates only when it is irradiated under the ultraviolet radiation of sunlight , and also,the electron hole of TiO₂ has very high reunited rate. Therefore, many researchers pay attention to doping other chemical elements or making compound of titanium oxide semi-conductor thin film as the valid way that improves its photocatalytic properties .However, much researches about TiO₂ modifying are the anatase and the rutile of TiO₂. And there are few reports about amorphous TiO₂ which is doped in other chemical elements. In this paper, amorphous TiO₂:W films deposited on the sildes by magnetron sputtering are studed.And the effecf of process parameters on photocatalytic properties of these films are disussed.TiO₂:W films were deposited on the slides with pure Ti and pure W targets. The components ,microstructure,luminousness,thickness and surface topography of the films were analysised via XRD, UV–Vis, XPS, ellipsometric examination and STM . The photocatalytic properties of these fims are characterized by the decomposition rate of methylene blue or rhodamine B. The effect of sputtering power, temperature, O2 mass flow,bias,W-doping and sputtering time on photocatalytic properties are discussed. TiO₂:Ni films are also prepared and discussed about its process parameters.The results of XPS showed that TiO₂:W films are amorphous. And Ti in the films are TiO₂ structure. W in the films are two forms——simple substance and WO3, and the ratio of two forms is 6.4:1.The experiments of decompositing methylene blue with the films of different thickness show that the threshold of thickness on these films are 141nm, before which the rate of decomposition increases, and when the thicknesses is over 141nm, the rate of photodegradation no longer increases.On the basis of UV-Vis transmissive spectra, the sputtered films have absorption peaks toward longer wavelength, and the calculation shows the lower optical band gap.