Synthesis And Modification Of TiO₂ By Dealloying Method And Its Photocatalytic Property

The dealloying method is used to fabricate porous nanomaterials, such as nanoporous metals and alloys, oxides supported nanoporous metallic materials. However, the studies on oxide semiconductors are rearly reported using dealloying method. Thus, it is vital to prepare semiconductors with above method for the development of nanomaterials.Photocatalysis is one of the most efficient ways to transfer sun-light energy to other forms. TiO₂ as a kind of semiconductor is widely used in photodegrading organic contaminants, photoelectric conversion and water photolysis. Nevertheless, pure TiO₂ almost possesses no visible light response because of its wide forbidden gap, which greatly limits its practical application. Therefore, it is a hot research topic in synthetising and modificating TiO₂, which extends the light response range from UV to visible light or near infrared region.In this paper, the precursor alloys were fabricated by mechanical alloying process or high vacuum single roll spin quenching system. Simutanionsly, the rutile and anatase TiO₂ with high specific surface area were synthetisedby dealloying method. Based on the preparation process of anatase TiO₂, the Ag, AgCl and Au nanoparticles modified TiO₂ were obtained though dealloying Al-Ti-Ag and Al-Ti-Au alloys, respectively. Finally, the photocatalytic activies were elevated by photodegrade methyl orange（MO） solutions under UV or visible light. The related research results are as follow:N-doped rutile TiO₂ with spindle morphology was fabricated by dealloying Cu-Ti alloys in concentrated nitric acid, which present excellent photocatalytic actives under UV or visible light irradiation by photodegrading MO solutions.Anatase TiO₂ with 3 dimensional network, random nanoclusters and spindle-like nanostructure was obtained using dealloying Al-Ti alloys in combination with calcination, water bath or hydrothermal treatment. During the process, the titanate as the important intermediate product, were aquried by dealloying Al-Ti alloys in NaOH solution. And, all the testedsamples photodegrade the MO solutions under UV light.The modified anatase TiO₂ from Au, Ag, AgCl has been also formed in the same method as that of anatase TiO₂. The Au or Ag nanoparticles loaded titanate was produced by dealloying the ternary alloys in NaOH solution. While, the Au and Ag nanoparticles modified anatase TiO₂ were fabricated by properly calcining Au or Ag nanoparticles loaded titanate. AgCl nanoparticles modified anatase TiO₂ was obtained with Ag loaded titanate treated in water bath. The samples present the enhanced photocatalytic activities under UV and visible light by photodegrading MO solutions. The photocatalytic mechanism was investigated in detail, indicating the close contacting interface between metal nanoparticles and TiO₂ is an important factor in enhancing photocatalytic activities under visible light.