Study On The Preparation Technology, Structure And Properties Of Doping TiO₂ Film Deposited By Direct Current Cathode Arc Evaporation

Since TiO2 split water to generate hydrogen was discovered by Fujishima in 1972, TiO2 has been extensively investigated in many promising applications for its excellent photoelectrochemical properties in non-toxicity, abundance, photostability etc., such as photocatalysis, sensors and cell batteries. However, the applications of TiO2 are still greatly limited for its large band gap and low electron-hole separation efficiency. Many studies have performed aiming at improving the photocatalytic performance of TiO2, including metals doping, nonmetals doping, codoping with two or more ions, modify the morphology of nanocrystals or create defects into crystal cell.Generally, non-mental N doping is considered to be one of the most effective approach to narrow the band gap of TiO2 result from generated N 2p levels above the valence band of titania and its similar radius compared to oxygen ion. Differ from previous preparation methods of doping TiO2 such as energetic ion bombardment, magnetron sputtering, sol-gel technique, hydrogenation and thermal treatment in reducing gases, a novel method is used to fabricate N doping TiO2 film in our experiment by thermal oxidization of N doping Ti film deposited by magnetic filtered cathodic arc and pulsed plasma arc technology in N2 atmosphere. The deposition parameters and annealing conditions were discussed in the process of preparing the film and its heat treatment. Also, the effects of substrate, arc current, pulse frequency, N2 partial pressure and annealing temperature on the structure, morphology and properties of deposited film and N doping TiO2 film were investigated. At the same time, the differences and similarities of these two kinds of coating processes are compared and analyzed, and the advantages of each process were summarized. The oxidation mechanism and crystallization behavior of N doped Ti film was speculated and analyzed in its oxidization process to generate N doped TiO2 film, as well as the existing form, lattice position and its position transfer of N ion in the initial state film and following heat treatment process. Except that, the effect of annealing temperature, the doping type of N ion on the energy gap and the UV-Vis absorption ability of the film were studied. By means of photocatalytic experiment, the effect of N dopant on the photocatalytic activity of N doping TiO2 film and its selective photocatalytic function on methyl violet and methyl orange mixed dye solution were explored and explained.