High Activity Oxide Catalyst Design And Synthesis Of Visible Light And Its Mechanism

Photocatalytic technology which is developed in recent years is a new environmental control technology, and has caught people's attention widely. Preparing the visible-light photocatalyst is the key for making this technology practical. To the problems of complicated technology and poor wide suitability in preparing nonmetal doped TiO₂ and large particle size and poor photocatalytic activity of BiVO₄ samples prepared by normal methods, we carried out the study of developing new methods to prepare non-metal doped TiO₂ and nano-sized BiVO₄ photocatalysts.O_n the basis of combining the advantages of hydrolysis process and solvothermal process, we developed the phase-separated hydrolysis-solvothermal process, and through it we prepared the TiO₂ which doped with N, S, Si et al controllable, the effects of reaction temperature et al on the photocatalytic activity of samples were mainly investigated. The results show that, comparing to the TiO₂ prepared by hydrolysis-hydrothermal process, the TiO₂ we prepared has better UV-photocataltic activity due to the higher crystalline degree and dispersibility. By introducing the ammonia et al into the water phase, we obtain the N et al non-metal doped TiO₂ simply. The non-metal doping enhances the visible light absorption of TiO₂ effectively, and the sample exhibits a good Vis-photocatalytic activity, it is worth noting to that the N-doped TiO₂ exhibits better photocatalysis activity than the sample prepared by high-temperature nitriding. In addition, the Si-doped TiO₂ with high thermal stability and photocatalytic activity which is better than the photocatalytic activity of P25 also can be obtained by introducing the C8H20O₄Si into the organic phase.To the problems the BiVO₄ particle is easy to grow too large in synthesis process, we developed a new method to prepare nano-sized BiVO₄ by introducing EDTA. And the effects of reaction temperature et al on the particle size of samples were mainly investigated. The results show that reducing the reaction temperature and time and increasing the addition of EDTA are benign to the controlling the particle size of BiVO₄, the BiVO₄ samples with an average particle size of 20 nm can be obtained. Based on the IR spectra, it is confirmed that the introduction of EDTA can be coordinate with Bi³⁺ to form a stable compound, consequently keeping a low-content free Bi³⁺ in the reaction system and then inhibiting the growth of BiVO₄ crystallites during the hydrothermal processes. The nano-sized BiVO₄ particles show a high Vis-photocatalytic activity, that is mainly due to its small particle size and large surface area.