Assembly Synthesis and Formation Mechanism of Dendritic and Spherical PbS Nanostructures

Single crystal dendritic and polycrystalline spherical PbS nanostructures were synthesized selectively with the assistance of surfactants sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) using Pb(Ac)2 as the plumbum source and TAA as the sulfur source. When the surfactant SDS is used only, the single crystal dendritic PbS nanostructure assembled by nanoparticles through the same crystallographic plane is synthesized. While the surfactants SDS and CTAB are used together, the polycrystalline spherical PbS nanostructure assembled by nanoparticles through the different crystallographic plane is fabricated. It is found that the size of the dendritic and spherical PbS nanostructures can be controlled by the concentration of reactants. Finally, The possible growth mechanism is discussed. It is found that the alkyl chain of SDS may work as a soft template to help the little PbS nanoparticles assemble into dendritic nanostructure while the surfactant SDS is used only. When another surfactant CTAB is added, the formed CTAB micelle in the solution will confine the growth of the dendritic nanostructure and the nanoparticles are obliged to assemble into spherical PbS nanostructure.