One pot and large-scale synthesis of nanostructured metal sulfides: Synergistic effect on supercapacitor performance

Abstract

Metal sulfides received key interest as an electrode material for storage and conversion of energy. Here, the novel nanostructured N17S18 and (CoNi)3S4 materials were synthesized via one-step hydrothermal method, and the synergistic effect of metal ions and electrochemical properties was investigated. A new and simple solution growth technique was employed in this work. The prepared nanopowders were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy techniques. The X-ray diffraction analysis of the prepared nanopowder revealed the formation of cubic phase cobalt nickel sulfides (CoNi)3S4 and hexagonal phase nickel sulfides (Ni17S18). Scanning electron microscopy analysis display fibrous, flakes and sheet-like morphology for CoxSx, N17S18 and (CoNi)3S4, respectively. Fibrous and sheet-like morphology exhibits higher electrochemical performance in supercapacitors. The electrochemical behavior of the amorphous CoxSx, crystallite Ni17S18 and (CoNi)3S4 modified electrodes was investigated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge techniques. The specific capacitance of 57 F/g and 31 F/g were obtained for the amorphous CoxSx and crystalline (CoNi)3S4 powder, respectively. Amorphous CoxSx modified electrode retains 76% of initial capacitance after 1000 repeated cycling process. These results of this study suggest that the CoxSx and crystalline (CoNi)3S4 are appropriate materials for supercapacitor applications.