Comparative study of electrocatalytic activity of single phase rhombohedral β-NiS nanoparticles in alkaline electrolytes

Facile Hydrothermal method is used for the synthesis of phase controlled β-NiS nanoparticles. Single phase formation of β-NiS nano-particles are identified through Rietveld refinement and their crystal structure is Rhombohedral. Average crystallite size of the β-NiS is 28 nm and energy band gap of β-NiS nanoparticle is found to be 3.25 eV. N2 adsorption-desorption isotherms study reveals that the synthesised β-NiS nanoparticle is a mesoporous material. In addition, reaction mechanism of β-NiS is also discussed in present work. For electrochemical studies, pure β-NiS is used as working electrode, without mixing of binder and carbonaceous material. Two alkaline electrolytes (KOH and LiOH) were used for electrochemical studies. During the Cyclic Voltammetry (CV) study, it was found that charge storage mechanism is Faradaic. The effects of various scan rates in specific capacity and areal capacity were studied in both electrolytes. Specific capacity of β-NiS is found to be 875.23 mAh in LiOH. β-NiS has more cycle life in LiOH as compared to KOH.