The Preparation And Application Of Modified TiO₂ Film With Visible Light Activity

TiO₂ as a represented photocatalytic environmental material has been extensively studied. Photocatalytic degradation of organics to protect environment become the most active research directions in the scientific community. TiO₂ as a photocatalyst with good performance is mainly reflected in its unique chemical stability and thermal stability, high efficiency, non-toxic, low cost. In photocatalytic reaction, due to wide band gap, TiO₂ can only absorb UV light (λ<387nm) to enable it to produce photo-excited electron-hole pair. So it can not make full use of sunlight, which greatly increases the cost of its application, limiting its application. Therefore, in order to expand its absorption of visible light and fully enhance its photocatalytic activity, non-metallic material doped TiO₂ has become the focus of attention in recent years.Iodine doped TiO₂ power was prepared by hydro-thermal synthesis method. The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue. However, TiO₂ power was easy to agglomerate and difficult to separate and reclaim in the process of photocatalytic reaction, so it is impossible to achieve industrialization. To solve the above problem, in this paper, focus on researching TiO₂ film prepared on the glass substrate. The idea of TiO₂ films modified with BO₃^3-,B₄O₇^2-,SiO₃^2- were put forword, then BO₃^3--TiO₂film,B₄O₇^2--TiO₂ film and SiO₃^2--TiO₂ film were prepared on the glass substrate. At the same time, the process of preparation without additive and without calcintion, was adapt to industrial production. The main results and conclusion obtained in the expriements of TiO₂ films were as follow:(1) Strip-like, needle-like and spherical BO₃^3--TiO₂ films were prepared. The influencing factors of addition of H₃BO₃ and O₂ on morphology were discussed. Spherical B₄O₇^2--TiO₂ films were prepared, the influencing factors of acid radical structure and addition of Na₂B₄O₇on morphology were studied. Needle-like and Strip-like SiO₃^2--TiO₂ films were prepared. The samples were charactered by XRD,UV-vis,IR,SEM,TEM,EDX, finally confirmed that SiO₃^2- doped in TiO₂ crystal lattice.(2) Under visible light irradiation (λ>420nm), the photocatalytic activity of SiO₃^2--TiO₂ films was evaluated by photocatalytic degradation of methylene blue. The influencing factors of morphology and pH were discussed; the photodegradation rato was up to 97%. SiO₃^2--TiO₂films were very stable, the photodegradation ratio kept 96% after 4 times recylings.(3) The formation mechanism of SiO₃^2--TiO₂ film, BO₃^3--TiO₂ film and B₄O₇^2--TiO₂film was studied. Confirmed that Ti(â…¢), stable acid radical and O₂ is the essential factors in forming this kind of TiO₂ film, the component of substrate influence the stability of film.