Temperature-dependent Hydrothermal Synthesis of NiS Nanoparticles for Morphological and Electrochemical Optimization as Supercapacitor Electrodes

Herein, NiS nanoparticles (NPs) were synthesized using the hydrothermal technique at temperatures of 140, 160, 180, and 200 ºC. The hydrothermal reaction temperature greatly influenced the structural and morphological investigations of NiS NPs. The SEM/TEM images confirm the rod-like formation of NiS NPs and EDAX shows Ni and S elements are present in NiS NPs. The XRD verifies the rhombohedral structural phase of NiS NPs. The cyclic voltammetry (CV), charging/discharging (GCD), and electrochemical impedance spectroscopy (EIS) reveal a rising trend in specific capacitance as the heating temperature increases, indicating that the temperature and morphology of NiS NPs influence the electrochemical performance in supercapacitors. The consistent matching of NiS XRD peaks in electrodes before and after cyclic stability testing further confirms the stability of NiS as a promising alternative to conventional electrodes in supercapacitors.