Synthesis And Photocatalytic Reduction Properties Of Modified Titanium Dioxide Films By Magnetron Sputtering

Titanium dioxide (TiO2) is one of the most widely studied semiconductor photocatalysts which can be used in waste water treatment, air purification, tail-gas treatment, et al. However, it can just absorb ultraviolet light as it has a wide band gap, and its quantum efficiency is also very low. Therefore, different elements were modified onto TiO2 to improve its photocatalytic activities.In this paper, nitrogen-doped titanium dioxide (TiON) thin films were first prepared by DC magnetron sputtering. The influences of nitrogen partial pressure, substrate temperature and sputtering gas pressure on structure, feature and photocatalysis of TiON films were investigated based on X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), spectrophotometer and homemade photocatalytic reactor. Then, Fe-modified TiON films and Pd-modified TiON films were prepared and investigated on the metal concentration and substrate temperature.The results show that the TiON films are composed of anatase phase while they turn to rutile gradually due to the existence of Fe or Pd. The parameters:nitrogen partial pressure 83.3%, substrate temperature 200℃, sputtering gas pressure 0.8Pa together make the best photocatalytic reduction properities of TiON films. When introducing Fe to TiON films, the parameters of the Fe-modified TiON films which have the best performances in photocatalytic reduction of Cr(VI) are 2.1 At.% of Fe and 350℃of substrate temperature. When introducing Pd on to TiON films, the parameters of the Pd-modified TiON films which have the best photocatalytic reduction properities are 0.4At.% of Pd and 300℃ of substrate temperature.The introduction of Fe and Pd to TiON thin films increases its effective absorption of visible light, as well as enhances its ability to capture electronic, and helps separate photo-generated electron-hole pairs effectively. It proves that optical band gap of TiO2 is adjustable. These results provide a valuable reference for the further investigation of visible-light sensitive TiO2 photocatalytic thin films.