Sulphide Doping Of Tio 2 </ Sub> Synthesis And Properties Of The Photocatalysts In <sub>

Bi2S3 and CdS doped TiO2 were prepared with different precursors via various techniques combinning sol-gel and hydrothermal methods. The doped TiO2 were characterized by XRD, SEM, TEM, XPS and UV-Vis diffuse reflectance means. The photodecolorization of 4-nitrophenol (4-NP) catalysised by doped TiO2 photocatalyst was examined. The main contents of this dissertation are listed as follows:1. The coordination compound [Sb(S2CNEt)3] (S2CNEt=pyrrolidinedithiocarbamate) was chosen as a precursors to get a homogeneous sol via mixing its chloroform solution with tetrabutylorthotitanate (TBOT). The homogeneous gel formed by displaying the sol 24h at room temperature, which facilely thermodecomposed into Sb sulfureted doped TiO2. Three synthetic routes, sol-gel(SG), sol-hydrothermal(SH) and gel-hydrothermal(GH) routes, were designed based on sol-gel and hydrothermal methods to get various Sb2S3 doped TiO2 photocatalysts. Using Bi(S2CNEt)3 instead of Sb(S2CNEf)3 as precursor, Bi2S3 doped TiO2 photocatalyst was prepared in the same way and investigated afterwards. High crstallinity and dispersion TiO2 was obtained by GH route. The effect of the synthetic routes, doped sulfied, doped concentration and the initial pH value of solution to the photodegradation of 4-NP were discussed. Results of 4-NP decolorization indicate that GH route is the optimal doped technique, and the optimal Bi2S3 and Sb2S3 content are 1.0 mol% and 3.0 mol% respectively and the optimal pH is 8.2. Another series of Sb2S3 and Bi2S3 doped TiO2 were synthesized by gel-hydrothermal route with two other coordination compound precursors (M(S2CNEt2)3, S2CNEt2= diethyldithiocarbamato, M=Bi, Sb) with different coordinated ligand to investigate the effect of the compound precursors on the photocatalysis properties of doped TiO2. Sb2S3 doped TiO2 with a concentration of 3.0mol% as obtained here performs the best photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP) among all the Sb2S3 and Bi2S3 doped TiO2.3. CdS nanoparticles were obtained by thermodecomposing cadmium stearate with a microwave reaction system in an ethanol solution. It was chosen as a precursor to obtain CdS doped TiO2 for it could form a homogeneous gel with TBOT isopropanol solution. By using gel-hydrothermal method, CdS doped TiO2 was synthesized from the homogeneous gel of CdS/TBOT isopropanol solution. The as-obtained CdS doped TiO2 shows a good crystallinity and a narrow dispersion size. Photocatalytic activity of dopants demonstrates that the CdS doped TiO2 powder has high photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP) compared with P25 under UV-vis illumination.Sb2S3, Bi2S3 and CdS doped TiO2 prepared by GH routes were anatase structured, and the crystallite sizes were approximately 20 nm with wormhole-like framework structures. In the Sb2S3 doped TiO2, XPS analysis showed that some sulfur ions (S6+and S4+) entered into the crystal lattice of TiO2, which resulted in the S doping. The absorption edges of Sb2S3, Bi2S3 and CdS doped TiO2 shifted to the longer wavelengthes. As the doping concentration increase, the absorption edges of Bi2S3 and CdS doped TiO2 also shifted to the longer wavelength, but the photocatalytic activity did not increase in the same trend. The photocatalytic activity of doped TiO2 is affected by various factors.