Synthesis And Properties Of TiO₂-Based Composite

TiO2 materials have been widely investigated due to its low cost, nontoxic nature and high photocatalytic activity. The major constraints for the practical application of TiO2 photocatalyst are its low quantum efficiency and short wavelength excitation. Therefore, this paper focus on design and development of new and efficient TiO2-based composite photocatalyst with higher photocatalytic activity. In this thesis, Ag/TiO2, Pd/TiO2 composites were successfully synthesized via a hydrothermal method and Ag/TiO2/AlOOH was also synthesized by a hydrothermal method with Boehmite as the carrier. The features of these photocatalytic materials, such as morphologies, phase structures, spectral response and so on were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption, UV-visible diffuse reflectance spectra (UV-vis). The photocatalytic properties of the samples were evaluated by the decomposition of dye Congo red (CR) as model pollutant, the major contents are as follows:1. The silver-doped titanium dioxide (Ag/TiO2) microspheres were synthesized by a single-step hydrothermal method and characterized by Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), UV-Vis diffuse reflection spectroscopy (UV-vis) and N2 adsorption-desorption. The photocatalytic activity of Ag/TiO2 composite was evaluated with the photocatalytic degradation of dye CR. The effect of the content of Ag-doped on the photocatalytic activity of the Ag/TiO2 was investigated. The results showed that the content of Ag was 0.4 at%, the photocatalytic property of the Ag/TiO2 sample was the most excellent and the photodegradation of CR with Ag/TiO2can be considered as pseudo-first-order reaction.2. Hierarchical structure AlOOH was synthesized successfully by a facile hydrothermal method. And the Ag/TiO2/AlOOH was also synthesized by hydrothermal method. According to the SEM images, the Ag/TiO2/AlOOH microspheres were assembled by nanosheets. The Ag/TiO2/AlOOH exhibited higher adsorption capacity and photocatalyst activity toward Congo red (CR) than those of TiO2 P25. This is attributed to the hierarchical structure of AlOOH, which provides the improved charge transport and the reduced recombination rate of photogenerated electron-hole pairs.3. The Pd/TiO2 was synthesized by a single-step hydrothermal method and characterized by Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), UV-Vis diffuse reflection spectroscopy (UV-vis). The photocatalytic activity of Pd/TiO2 composite was evaluated with the photocatalytic degradation of dye CR.