Controllable synthesis of NiS and NiS₂ nanoplates by chemical vapor deposition

Mulitipe stoichiometric ratio of two-dimensional (2D) transition metal dichalcogenides (TMDCs) attracted considerable interest for their unique chemical and physical properties. Here we developed a chemical vapor deposition (CVD) method to controllably synthesize ultrathin NiS and NiS₂ nanoplates. By tuning the growth temperature and the amounts of the sulfur powder, 2D non-layered NiS and NiS₂ nanoplates can be selectively prepared with the thickness of 2.0 and 7.0 nm, respectively. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization reveal that the 2D NiS and NiS₂ nanoplates are high-quality single crystals in the hexagonal and cubic phase, respectively. Electrical transport studies show that electrical conductivities of the 2D NiS and NiS₂ nanoplates are as high as 4.6 × 10⁵ and 6.3 × 10⁵ S·m^-1, respectively. The electrical results demonstrate that the synthesized metallic NiS and NiS₂ could serve as good electrodes in 2D electronics.