Co9S8 nanoflakes on graphene (Co9S8/G) nanocomposites for high performance supercapacitors

Abstract

Co₉S₈/graphene nanocomposites (Co₉S₈/G) at various concentrations of graphene and Co₉S₈ were prepared by a simple chemical route from cobalt nitrate and graphene as precursors in the presence of PVP as surfactant and thioacetamide (TAA) as sulfur source. To gain knowledge about the structural, morphological and physical properties, the composite material was analyzed by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric Analysis (TGA). SEM measurements showed the presence of well dispersed, ∼300 nm sized Co₉S₈ nanoflakes. To assess the properties of the nanocomposites for their applicability in supercapacitors, electrochemical analysis was carried out in 6 M KOH electrolyte. A maximum specific capacitance of 808 F g⁻¹ was observed for Co₉S₈/G-d at 5 mV s⁻¹ scan rate. Galvanostatic charge–discharge curves showed the excellent cyclic stability of Co₉S₈/G-d composite with higher charge–discharge duration than pure Co₉S₈. The excellent electrochemical performance of the composite could be due to the better electrical conductivity behavior of graphene on Co₉S₈ nanoflakes.