Synthesis of ZnS Nanoflowers by Composite-Hydroxide-Mediated Approach

Zinc sulfide nanoflowers are synthesized by the composite-hydroxide-mediated (CHM) method, using molten composite hydroxides as a reaction solvent, sodium sulfide and zinc nitrate hexahydrate as reactants at temperature of 200 degrees C in the absence of organic dispersant or capping agents. The XRD spectrum of the as-synthesized sample indicates a cubic ZnS with lattice group F (4) over bar 3m[216] and lattice constant a = 5.318 angstrom. The scan electron microscopy and transmission electron microscopy display its good crystallization and flower shape with diameter of 800-1000 nm. The photoluminescence results reveal that the ZnS nanocrystal has a band gap of 3.4 eV. The strong blue emission centered at 440 nm demonstrates the existence of defect states. This CHM approach provides a useful route for the synthesis of ZnS crystals, which may be extended to synthesize other II-VI semiconductors.