| Core-shell nanocomposites have been prepared by many approaches methods, such as precipitation, solvothermal, microemulsion, template and sol-gelatin methods. This dissertation presented an improved pyrolysis method to prepare core-shell nanocomposites. In all prepration procedure, the organometallic compounds are seleted as the single-source precursors to obtain metal sulfide@carbon core-shell nanocomposites by the improved pyrolysis approach. The obvious merits of this method are the single-source precursor, the simple operation without the virulent organic solvent, and little environmental pollution. A specifical and universal research has been performed for the improved technique in this work, and many kinds of metal sulfides coated by carbon nanomaterials have been prepared, which provides one kind of new idea to prepare other type core-shell nanocomposites. The main research contents are as follows:1. Bis(2-mercaptobenzothiazolato)-cadmium (II) was obtained with 2-mercaptobenzothiazolato as the ligand. CdS@GNS nanocomposite was prepared by the improved pyrolysis of bis(2-mercaptobenzothiazolato)-cadmium (II) as the single-source precursor. This method is a simple, effective and economical approach, which solves the sintered problem, occurred usually in conventional pyrolysis preparation process. The fluorescence test indicates that the studied material presents good fluorescence characteristics. Moreover, the prepared conditions consisted of the reaction time and the heating temperatures have been researched in order to improve fluorescent intensity of the as-prepred products. The results show that the product presents the best fluorescent intensity when heating temperature is at 700℃and the heating time is at 5 h.2. The ligands types have been studied to influence the product appearance, size and characteristics.B-mercaptoethanol was as the ligand to prepare the CdS@C nanocomposite. Compared with CdS@GNS nanocomposite, the CdS particles became spherical, and the carbon shell became amorphous. The fluorescence test indicated that the product also has the good fluorescence characterstics. However if the surface-active agent is joined in the preparation process, the fluorescence of the product is declining.3.1-dodecanethiol was as the ligand to prepare carbon-coated CdS quantum dots. Compared with the CdS@C nanocomposite, the size of the product becomes smaller, the core diameter has been changed from 12 nm to 5 nm, and the carbon shell thickness has been changed from 4 nm to 2 nm. The fluorescence test result indicates that the product also has good fluorescence propreties. The electrochemistry test indicates that the electric charge is primarily transmitted by the diffusion control. The electric capacity characteristics are mainly the Faraday electric capacity caused by the redox reaction. With the surface-active agent, the specific capacity of CdS@C compound increases compared with the other product without surface-active agent, owning to the increase of carbon composition of the product.4. ZnS@C,NiS@C,CuS@C and FeS@C nanocomposites have been prepared by the improved pyrolysis technology with the three ligands mentioned above as single-source precursors.1) The experimental results show that the types of ligands and metal ions have effect on the morphology of the products.2) Electrochemical tests results show that ZnS@C, NiS@C and CuS@C electrode reactions present quasi-reversible phenomenon, and the capacitances of the products have been improved greatly compared with pure sulfide, and the electric charges are primarily transmitted by diffusion control. In addition, the capacitance of ZnS@C, NiS@C and CuS@C increases orderly.3) Fluorescence test results show that for the same metal ions, the fluorescent intensities of the sintered samples are better than one of the acid treated samples, and the fluorescent intensities of the samples with surfactant are weaker than one of the samples without any surfactants. In a certain range, the longer the reaction time, the stronger the fluorescence intensities of the products. For different metal ions, the fluorescence intensities are in the sequence of ZnS@C> CuS@C> FeS@C> CdS@C> NiS@C.
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