Hydrothermal Growth and Morphology Modification of β-NiS Three-Dimensional Flowerlike Architectures

A series of β-NiS three-dimensional (3D) flowerlike architectures with an average diameter of 2−4 μm have been hydrothermally synthesized in the presence of ammonia and trisodium citrate. Morphology modification can be conveniently realized by varying the reaction temperature. At 120 °C the flowerlike architectures were composed of nanoneedles. At 180 °C the flowerlike architectures were composed of nanorods, while mixtures of nanoneedle-based and nanorod-based flowerlike architectures were obtained in the temperature range of 140−160 °C. Citrate anion was introduced as both a coordinating reagent and a shape modifier to control the anisotropic growth of β-NiS. Besides a probable growth mechanism, the citrate-assisted Ostwald ripening process was proposed to explain the formation of flowerlike architectures on the basis of transmission electron microscopy observations. Such a simple and mild synthetic route may be extended to fabricate complex 3D architectures of other materials.