Preparation And Photocatalytic Study On Amorphous TiN/Ag/Cr-TiO₂Thin Films

In recent years, titanium dioxide photocatalyst is widely used in environmental applications, especially in further development of water pollutants treatment. The prominent advantages of titanium dioxide for pollutants photocatalytic degradation are High efficiency, energy saving, clean, non-toxic and stability. On one hand, however, the Titanium dioxide absorption edge is located in ultraviolet region, which result in low utilization rate of solar energy; on the other hand, the separation of powdery titanium dioxide photocatalyst from suspension is very difficult, it cost a lot in water treatment. These problems cause some obstacles to the practical applications in the usage of titanium dioxide and make the titanium dioxide become the most attractive photocatalyst for environmental remediation study.In this paper, a background on titanium dioxide structure, properties and electronic properties in photocatalysis is presented. Applications in environmental remediation for titanium dioxide are elaborated. The strategies to modify titanium dioxide and methods for preparation titanium dioxide thin film are summarized. The Ti N/Ag/Cr-Ti O2 multilayer thin films were prepared by the reactive magnetron sputtering technique on the microscopic glass and monocrystalline silicon slice and studied the influences of thin film preparation parameters in photocatalytic properties. Properties of the thin films were analyzed via X-ray Diffraction(XRD), Scanning Electron Microscope(SEM), Energy Dispersive Spectrometer(EDS), X-ray photoelectron spectroscopy(XPS), UV-vis spectrophotometer and surface profiler. The thin film photocatalytic tests were performed with an aqueous solution of methylene blue. And the basic properties and photocatalytic degradation efficiency in different Ag layer thickness or Cr target powers are discussed in this paper.The results in XRD, EDS, XPS indicated that the Ti N/Ag/Cr-Ti O2 multi-layer thin films are amorphous. The distribution of Ag, Cr, Ti, O are evenly distributed and the state of these element are analyzed. The results of UV-vis spectrophotometer analysis showed the band gap(Eg) of titanium dioxide thin film greatly reduced when added Ag layer and doped with Cr element. The experiments of photocatalytic degradation methylene blue suggest that it can prepare thin film with optimal degradation efficiency through changing process parameters and designing in each thin film and the doping element. These methods can change thin film surface morphology, introduce impurity energy levels and crystal defects, effectively reduce the rate of the recombination of photo-induced electrons and holes.