Narrow Results

We herein demonstrated the preparation of nickel sulfide hierarchical architectures via an emulsion-assisted route in hydrothermal system. Scanning electron microscope images of the products at different reaction stages indicated that the construction of the nanostructured hierarchical nickel sulfide was accomplished through oriented attachment accompanied by an encapsulation procedure, and the as-obtained products exhibited uniform architectures assembled by various primary units (e.g. nanorods, nanosheets). In addition, the effect of different surfactants on the shape of nickel sulfide nanostructures was further studied. The results indicated that the hierarchical architectures can only be achieved with the assistance of anionic surfactant (e.g. sodium dodecyl sulfate). These as-prepared novel hierarchical nanostructures may be used in various areas, including industrial catalysis, and energy storage etc.

Cobalt(II)/Nickel(II) complexes of 4-thiopent-3-ene-2-thione (SacSac), [M(SacSac)₂](M = Co, Ni) have been used as single source precursors (SSPs) for the preparation of cobalt/nickel sulfide thin films by aerosol-assisted chemical vapor deposition (AACVD). Cobalt or nickel sulfide nanoparticles were grown by thermal decomposition of the precursor in hot trioctylphosphine oxide (TOPO) or hexadecylamine (HDA). XRD analysis showed that all samples of cobalt or nickel sulfide are of the sulfur deficient phases (Ni₉S₈, Co₉S₈, Ni₇S₆, or Ni₃S₂). SEM and TEM analysis showed that nickel sulfide formed nanowires, nanorods and spheres; cobalt sulfide formed plate like structures and spheres. The chemical compositions of the nanoparticles can be controlled by varying temperature or the capping agents.

Nickel sulfide series nanoparticles were synthesized by a simple solvothermal reduction method of nickel chloride and element sulfur in the oleylamine solvent. This method could offer potential advantages of mildness, safety, low cost, and simplified fabrication procedures. Through the adjustment of Ni/S raw material ratio, different phases of nickel sulfide, including cubic NiS₂, hexagonal NiS, orthorhombic Ni₇S₆, and trigonal Ni₃S₂ were obtained. In addition, the sulfur sources played important roles in the synthesis of nickel sulfide series compounds. The possible growth mechanisms had been discussed based on the influence of reaction temperatures and solvents on the phase structure and detailed composition of the final products. Finally, the obtained optical properties demonstrated that each sample had the unique absorption peak except cubic NiS₂.

A facile, one-pot solvent-mediated hydrothermal process was adopted to prepare nickel sulfide nanoparticles decorated on reduced graphene oxide (Ni_xS_y/rGO) as electrocatalysts for hydrogen evolution reaction (HER). The designed solvent (ethylene glycol and deionized water) played a decisive role in controlling both crystalline phase and morphology of Ni_xS_y/rGO composites, leading to pure $\alpha$-NiS nanoparticles uniformly distributed on rGO sheets under suitable volume ratio of ethylene glycol and deionized water (2:1). The optimized $\alpha$-NiS/rGO showed prominent HER catalytic performance with a rather small Tafel slope of 93mV/decade and prominent current density of 10mA/cm² at the overpotential of 177mV in alkaline environments when compared to pristine $\alpha$-NiS and NiS₂/rGO catalysts. The excellent catalytic performance and long-term durability even after 8000 cycles confirmed the potential of $\alpha$-NiS/rGO composites as efficient electrocatalysts for HER in the alkaline media.

Nanostructured nickel sulfide as a cathode material for lithium ion batteries was fabricated. The large surface area of reaction between electrodes and electrolyte offers high energy density and capacity. Also, metal sulfides have high theoretical capacity. Nickel nanowires were fabricated by electrochemical deposition (ECD) using an anodic aluminum oxide (AAO) template with the diameter of 200 nm. Fabricated nickel nanowires were carried out with sulfuration treatment. The morphology and microstructure of the nanowires were characterized with FE-SEM, XRD, TEM and XPS. Nickel sulfide nanowires were applied for lithium ion batteries and charge/discharge tests were carried out with galvanostatic method.