Enhanced Electrochemical Performance of Hydrothermally Synthesized NiS/ZnS Composites as an Electrode for Super-Capacitors

Abstract

In this study, nickel sulfide (NiS), zinc sulfide (ZnS), and their composites have been synthesized by using surfactant driven hydrothermal method. Synthesized materials are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy, UV�Vis and Photoluminescence spectroscopy. XRD results have shown the presence of corresponding structural planes. Crystallite size was much smaller (15�nm) in the case of ZnS nanomaterials, whereas, composite materials have shown size comparable to NiS nanomaterials. SEM images presented morphology of star-like, spherical, and mixture of two for NiS, ZnS, and NiS/ZnS nanocomposites respectively. EDX spectrum of composite materials showed Nickel, Zinc, and Sulfur, indicating the purity of the synthesized composite. Electrochemical measurements i.e. cyclic voltammetry and galvanostatic charge�discharge were determined for all three materials. Maximum specific capacitance is obtained as 1594.68 F�g?1 at a scan rate of 5�mV�S?1 for NiS/ZnS composite materials whereas a charging/discharging time of 461.97�s is observed. The composite materials have shown 95.4% retention for applied for 3000 charging�discharging cycles. The favorable behavior of NiS/ZnS composites indicated their potential as an electrode material for pseudo-capacitors. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.