Controlled Synthesise Of Sulfide Nanocrystals And Their Photocatalysis Properties

In this dissertation, the microstructure control of semiconductor Bi2S3and PbS were studied, and the photocatalysis properties of Sb2S3/Bi2WO6under visible irradiation with Rhodamin B as a stimulant polluted water were studied, and the main contents and results are discussed as follows:Bismuth sulfide (Bi2S3) nanorods, microglobes assembled by nanosheets or nanorods were synthesized from the bismuth xanthates precursors in N,N-Dimethylformamide solution at80℃for2days. The obtained Bi2S3nanostructures were characterized by XRD, EDS and XPS, which show that the products belonged to the orthorhombic Bi2S3phase and were highly pure. The optical properties of Bi2S3in various shapes were studied by UV-Vis diffuse reflectance spectra, indicating that these Bi2S3nanoparticles commonly exhibited a broad absorption from200nm to800nn. And the dispersed Bi2S3nanorods obviously displayed higher absorption intensity than globular ones, which may be possibly attributed to the quantum size effect. Transmission electron microscopy (TEM) and the scanning electron microscopy (SEM) revealed the various morphologies of the products prepared from different precursors, showing that the chain length and structure of xanthates played an important role on the morphology of Bi2S3nanostructures. The formation mechanism of Bi2S3nanostructures was discussed and we came to the conclusion that nanorods may come into being prior to the nanospheres due to the longer linear alkyl chain of the precursor. Meanwhile, compared with the linear chains, branched chains may be benifit for the nanoparticles to grow into microstructures assembled by nanoplates. Considering flexible ring-shaped groups may have stronger growing dynamics, the cyclohexyl groups may do a favor for the formation of longer Bi2S3nanorods in comparison with the rigid one.Single-crystalline PbS hexagonal nanoplates were obtained via two-phase methods at room temperature for4days, when dimethyl sulfoxide (DMSO) was used as the solvent instead of DMF when other reaction conditions remained the same, microspheres assembled by nanocubes were obtained.The products were characterized by means of XRD, EDS and XPS showing that the products belonged to the orthorhombic PbS phase and were highly pure. TEM and SEM revealed that the PbS nanoplates were with an edge length of approximately400nm and thicknesses of about50nm, and the nanocube-based PbS microspheres were with a diameter of2-4μm. The influences of lead source and solvent on the morphologies of the products were investigated and a time-dependent experiment was also been conducted to track the morphological evolution of the plate-like and spherical PbS nanoparticles.Sb2S3/Bi2WO6heterojunctions with different mass ratios were prepared by the hydrothermal process. The Sb2S3/Bi2WO6was characterized by XRD. The optical properties of Sb2S3/Bi2WO6were studied by UV-Vis diffuse reflectance spectra. The photocatalysis properties of Sb2S3/Bi2WO6under visible irradiation with Rhodamin B as stimulant polluted water were studied. SEM reveals the morphology of the products. It was found that when the the percentage of Sb2S3is5%, the photocatalytic activity of the complex was the best. In addition, we also studied the influence of dopping amount of Sb2S3on the sample’s adsorption properties and the influence of chelating agent on the photocatalysis properties of the products.