Tuning the electrochemical properties of NiS2 2D-nanoflakes by one-zone sulfurization for supercapacitor applications

Abstract

Nickel-based sulfides (particularly NiS2) are regarded as promising materials for highly efficient electrochemical generation and storage devices. The conventional fabrication methods of nanostructured NiSX electrodes involve several complex steps using multiple precursors and techniques. In this paper, the NiSX electrodes are prepared by a plain one-step process of one-zone sulfurization of Ni foam. The evolution of highly electroactive 2D-nanoflakes reliant on sulfurization temperature is studied. Scanning electron microscopy, x-ray diffractometry, and energy-dispersive x-ray spectroscopy confirmed the presence of NiSX (x = 1 and 2) in the prepared structures. A strong dependence of sample morphology and 2D-nanoflakes density on sulfurization temperature was demonstrated. The electrochemical properties of samples were characterized by cyclic voltammetry and electrochemical impedance spectroscopy measurements. Owing to the 2D-nanoflake structure, the NiS2 showed attractive electrochemical performance, including a high specific capacitance of 648 mF cm−2 and a capacitance retention rate of 90,7% after 3000 cycles. Our study shows that the composition and crystal growth of NiSX can be tuned by reaction temperature during the sulfurization and high perspective of sulfurization in the synthesis of highly electroactive large-scale electrodes for supercapacitors.