Synthesis, Characterization And Optical Property Research Of Metal Chalcogenide

Many metal chalcogenides nano/micro crystalline were synthesized byusing hydro-/solvothermal process in this thesis. The morphology and particlesize of the products are tunable by changing the ration of reactants, the kind ofsolvents, the pH value of solution, the reaction temperature and react time, etc.Furthermore, the formation mechanism of products with different morphologywas proposed. The main contents of this thesis were submitted as following.1. Copper chloride dihydrate and dithizone were employed as reactants tosynthesize CuSCN via a benzene thermal route. The product was firstcharacterized by XRD. The resust shows that the as-prepared product has ahexagonal phase and good crystallinity. The morphogy and particle size of theproduct were characterized by SEM, it shows that the product is composed ofhollow spheres and the diameter is about5μm. Moreover, the effects of reactiontime on the morphology of the product were also investigated, and theas-obtained intermedia products were characterized by SEM. Then awater-induced template mechanism was proposed to crack the formation of thehollow structure. At last, the optical property was also examined by UV-visabsorbtion spectrum.2. Cadmium nitrate and sodium diethyldithiocarbamatre （NaDDTC） asreactants and diethylenetriamine （DETA） as solvent. CdS nanorods weresuccessful synthesized via a solvothermal method. XRD shows that the producthas a hexagnol phase. The morphology of CdS was characterized by SEM, theresult shows that the product has spindle-like structure. By changing the reactiontime, the intermediate products were obtained. Results show that CdSnanoparticles are formed at the initiation stage and then the nanoparticles growinto nanorods. Next, the as-obtained nanorods split and grow furhter intospindle-like structure. Based on the experimental facts a growth-splitting-growth mechanism was proposed. The optical property was characterized by UV-visabsorbtion spectroscopy. There exsit two peaks （489and500nm） around490nm,it maybe due to the special spindle-like structure or the crystal defect.3. Urchin-like NiS nanocrystals were synthesized by a simple solvothermalmethod using NiCl₂6H₂O as Ni source and diethyldithiocarbamic aicd sodiumsalt trihydrate （DDTC-Na） as S source. The phase and the purity werecharacterized by X-ray powder diffractometer （XRD）. It is found that theas-prepared product is the pure hexagonal phase. The optical microscopy andscanning electron microscopy （SEM） show that the as-prepared products have anurchin like morphology. Further more, it is found that the molar ratio betweenNiCl₂6H₂O and DDTC-Na can affect the morphology of NiS and uniformurchin-like NiS nanocrystals can only be obtained when the molar ratio is1:2. Atlast, based on the facts of time-depended experiments, a possible formationmechanism of the urchin-like NiS nanocrystals was proposed.4. BiCl₃and thiosemicarbazide were used as Bi-source and S-sourcerespectively, and Bi₂S₃rod-like structure was successfully synthesized at180℃for24h. XRD result shows the product has an orthorhombic structure, and thepurity and crystallinity are very good. SEM images show that the productconsists with lots of rod-like structure. The diameter of the nanorod is about300nm and the length ranges from5to8μm. During the synthesis process, thepH value of solution and the kind of solvent were found to have great influenceon the morphology of the product. Low pH value（pH<1） is favorable for theformation of rod-like structure, and high pH value is suitable for the formation ofnanoflakes. It is similar to solvent, when high viscosity solvent were used, i.e.ethylene glycol（EG）, glycerol, flower-like structure composted of nanorods wasobtained. When low viscosity solvent was used, i.e. water, ethanol, rod-likestructure obtained.5. ZnS particles were synthesized successfully using CS₂as S-souce andzinc acetate as Zinc-souce via a hydrothermal synthesis at170℃for24h. Next,the as-prepared ZnS was used as the substrate and ZnS/CdS composite materialwas obtained by a wet chemical method. The obtained ZnS and the compositematerial were characterized by XRD, EDX, SEM, optical microscopy andUV-vis absobtion spectrum. XRD pattern shows that the obtained ZnS has a hexagonal phase. Mean while EDX shows that CdS has been coated on ZnSparticles. The morphology and size of the product was observed by SEM andoptical microscopy, results show that the obtained ZnS has a hollow spherestructure, and the diameter of the sphere is about2μm, and twin structure couldalso be found. Based on the experimental dates, a sacrifice template mechanismwas used to illustrate the formation of ZnS hollow sphere. At last UV-visabsorbtion spectrum was used to investigate the photocatalysis property onphotodegradating Methyl Orange, Pyronine and Rhodamine B of ZnS andZnS/CdS. Results show that the photocatalysis property of ZnS/CdS is betterthan that of ZnS.