Hydrothermal Synthesis And Characterization Of Metal Sulfides Nanostructures

Owing to unique physical properties, nanostructured metal sulfides have exhibited promising applications in many fields such as optics, sensor, catalysis, magnetics and solar cells. Preparing novel nanostructures and investigating their general formation mechanism may be a solution to the precise control of their sizes, dimensionalities and properties. At present, the preparation of metal sulfides has made a great progress, but their shape-controlled synthesis is not solved still. Therefore, large-scale, cost-effective, simple and practical synthesis and assembly of metal sulfides with different shapes is of importance for the fundamental research and applications.We prepared a few kinds of metal sulfides with different shapes using a simple hydrothermal method assisted by surfactants, including spheric, cubic, clubbed, starlike and dumb-bell shaped PbS, spheric ZnS and CdS, tubular MnS, etc. The reaction time, temperature, reactant concentration and surfactants were investigated in order to learn about how they affect the shape of the products. Finally, we made a primary study of the formation mechanism of the synthesized nanomaterials with different shapes.PbS nanorod bundles were synthesized hydrothermally at 120℃for 12 h, by using Pb(CH₃COO)₂-3H₂O and CH₄N₂S as raw materials, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfonate (SDS) as surfactants. The as-prepared samples were characterized by X-ray powder diffraction (XRD), high resolution transmission electron microscope (HRTEM) and transmission electron microscope (TEM). The analysis results show that the as-prepared PbS nanorods are pure cubic phase, single crystalline and present rod-like morphology. Moreover, when the molar ratio of the two reactants was 1:1, a mass of PbS nanorod bundles were obtained. When only CTAB as a surfactant was added, and CH4N2S as the sulphur source, starlike PbS nanostructure was obtained at 160℃for 6 h, but when the sulphur source was replaced by sodium thiosulfate, the obtained product was dumb-bell shaped nanostructure at 120℃for 6 h. When both the SDS and CTAB were added, and the sulphur source was thioacetamide, spheric nanostructure which was conglutinated by the nanoparticles was obtained at 120℃for 12 h. When the reaction temperature increased, the shape of the obtained products was different. The hollow cubic PbS and cubic PbS were obtained at 120℃and 160℃, respectively.According to the synthesized principle of spheric PbS nanostructure, we prepared other spheric metal sulfides successfully, such as ZnS, CdS, etc. The tubular MnS nanostructure was obtained by using the SDS/CTAB mixture, but the formation mechanism needs to be further investigated.