Electrochemical and electronic properties of flower-like MoS2 nanostructures in aqueous and ionic liquid media

Abstract

In the present work, we report a facile strategy to synthesize uniform 3D flower-like MoS₂ nanostructures prepared by a one-pot hydrothermal method and investigate their supercapacitive behavior. A field emission scanning electron microscopy, atomic force microscopy and X-ray diffraction study reveals the formation of randomly stacked layers of MoS₂. The electrochemical properties of MoS₂ nanostructures were investigated using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectra (EIS) techniques in aqueous and ionic liquid media. The CV measurement shows that the as-synthesized MoS₂ electrode delivered a maximum capacitance of 218 F g⁻¹ at a scan rate of 5 mV s⁻¹ in aqueous medium. The GCD measurement shows a maximum specific capacitance of about 217.6 F g⁻¹ at a discharge current density of 0.1 A g⁻¹ in aqueous electrolyte. EIS with an appropriate electrical equivalent circuit was employed to understand the charge storage mechanism in the MoS₂ electrode. Cyclic stability tests in aqueous medium reveal a capacitance retention of about 76% after 1000 cycles. This study reveals that a nearly pure capacitive behavior is observed for aqueous electrolyte and a diffusive behavior is observed for the MoS₂ electrode in ionic liquid medium.