Biomolecule-assisted synthesis of flower-like NiS microcrystals via a hydrothermal process

Flower-like NiS microcrystals built of nanoflakes have been synthesized via a hydrothermal process in the presence of L-cysteine, trisodium citrate, and ammonia. L-cysteine was employed as sulfur source and surfactant to regulate the nucleation and growth process. Citrate anion was introduced as both a coordinating reagent and a shape modifier to assist synthesis of flower-like NiS microcrystals. Furthermore, the influences of pH value, reaction time, and hydrothermal temperature on the morphologies of final products were carefully studied. The phase structures, morphologies, and properties of the as-prepared products were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and photoluminescence spectra (PL). The possible growth mechanism for the formation of flower-like NiS microcrystals was preliminary investigated on the basis of our experiments. (C) 2009 Elsevier B.V. All rights reserved.