Preparation, Structure Characterization, Modification And Visible-light Activated Photocatalytic Performance Of TiO₂ Thin Films From Peroxo Titanic Series Sols

According to the current problems such as low quantum efficiency, limited available visible light energy spectrum range, and inefficient recovery, the novel peroxo titanic series sols PTA, AS and RS were prepared by the method of hydrogen peroxide solution peptization, autoclave or reflux treatment using inorganic titanyl sulfate (TiOSO4) as raw materials, the properties and preparing process of the peroxo titanic series sols were discussed in detail. The nanometer photocatalytic TiO₂ thin films were synthesized from the obtained three peroxo titanic series sols by dip-coating method, a wide range of testing techniques were applied to characterize the TiO₂ thin films. The influences of technological parameters on the structure, composition, optical absorption and photocatalytic performance of TiO₂ thin films were investigated in detail. A series of doped TiO₂ thin films were prepared by adding the metals such as Fe, W, Ag, Pd and novel semiconductor InVO4 with narrow band gap. The effects of dopants on the structure, composition and the photocatalytic properties of the doped TiO₂ thin films under UV and visible light irradiation were emphatically explored, and the doping mechanisms to achieve the visible light photocatalytic activity were proposed in this paper.The three peroxo titanic series sols are stable at room temperature, thereinto the PTA sol is yellow, transparent and keeps stable, the pH value keeps neutral. The forming mechanism of the PTA sol is discussed based on the principles of inorganic chemistry and results of experiments, the results indicate that PTA sol is consisted of colloid particles which homogeneously dispersed in water, the colloid particles are composed of peroxo titanic acid polymers with Ti2O5(OH)2(H2O)2 structural units, the PTA sol keeps stable by the mutual repulsion between the negative charges in the colloid particles. While the AS and RS sols are flavescent, semitransparent, alkalescent and stable, their pH values are about 7⁸, the sols contain needle-like anatase TiO₂ crystals and keep stable by the mutual repulsion between the negative charges on the surface of anatase crystals. The forming process of the AS sol under hydsothermal conditions is investigated in this paper according to the hydrothermal chemistry and crystallography. The growing speed along with the c axis in anatase structure is the fastest for the particularity of the anatase phase, and lead to the...