Studies On The Photocatalysts Of N Doped And B-Doped Nano-Titania

Among the semiconductor photocatalysts, TiO₂has been widelyconcerned because of its high photocatalytic activity, chemical stability,cheapness, and non toxicity. It has bright prospects in many fields such asenvironment protection, solar battery, and gas sensitive materials etc.However, TiO₂with wide band gap can only be excited by less than387.5nmultraviolet light and is greatly restricted to the effecient utilization of solarenergy. Therefore, how to excite under visible light irradiation and improvequantum yield of TiO₂by modification have become a hotspot inphotocatalysis research. In this thesis, the preparation and photocatalyticactivity of nitrogen doped （N/TiO₂） and boron doped TiO₂（B/TiO₂）photocatalysts using hydrothermal and shock wave methods were studied. Themain experimental results were summarized as follows:（1） A serial of N/TiO₂photocatalysts were synthesized by hydrothermalmethod using Ti（OC4H9）4and hydrazine hydrate as precursors. The effects ofthe different factors such as pH, reaction temperature and doping content onthe structures and photocatalytic properties of TiO₂were obtained. N doping can effectively restrain the growth of TiO₂grain and lead to the redshift ofTiO₂absorbance edge. N/TiO₂photocatalyst with2.41%（at.%） N contentsynthesized at the condtions of pH=7,180°C shows the best photocatalyticacitivty for degradation of RB.（2） The powder mixtures of rich nitrogen dopants of C₂N₄H₄and P25TiO₂or metatitanic acid were shocked using the impact of flyers driven byexplosive detonation. The results indicate that the doping level is the8.88%（at.%） using the P25as raw materials which exhibited the obvious adsorptionin visible region. Its energy gap increased to1.75eV together with theformation of little high pressure phase of srilankite. The doping level is the3⁴%（at.%） corresponding the small variety of the energy gap using themetatitanic acid as raw materials. The specific surface area of the samplehas increased drastically arisen from the unique shock dehydration expansionmechanism.The shock doped samples have better adsorption andphtotocatalytic activity under visible irradiation for the degradation of MB andRB, among which the sample to be treated at highest flyer velocity shows thehighest photocatalytic acitivity.（3） B/TiO₂photocatalysts were synthetized by hydrothermal methodusing boric acid and sodium borohydride as the boron source respectively.Results indicate that there are optimum amount of boron source （0.1and.6grespectively） for the improvement of photocatalytic activity in the B/TiO₂samples. B/TiO₂photocatalyst synthesized at the condtions of pH=7,180°C shows the best photocatalytic acitivty for degradation of RB. Two boronresources with adding different amounts exhibit similar effect of boron contenton the photocatalytic activity.（4） TiO₂nanotubes （TNTs） have also been studied preliminarily.TheTNTs synthesized under hydrothermal conditions are about10nm in diameterand50～100nm in length.The possible formation mechanism was proposed．...