Facile synthesis of nickel–cobalt sulfide/reduced graphene oxide hybrid with enhanced capacitive performance

Abstract

A uniform hybrid with nickel–cobalt sulfide (NiCo₂S₄) nanoparticles attached on reduced graphene oxide (RGO) nanosheets is fabricated through a facile one-pot refluxing method. NiCo₂S₄ nanoparticles with sizes of several nanometers uniformly disperse on the surface of RGO sheets, and the electrochemical properties of the resulting NiCo₂S₄/RGO hybrids are investigated by using them as electrode materials for a supercapacitor. The NiCo₂S₄/RGO hybrids deliver a maximum specific capacitance of 1526 F g⁻¹ at the current density of 1.0 A g⁻¹, and a high rate capability, retaining 1109 F g⁻¹ at a high current density of 20 A g⁻¹. Moreover, after 2000 charge–discharge cycles at the current density of 10 A g⁻¹, 83% of the initial capacitance is maintained, indicating a good cycling stability. The enhanced capacitive performance can be attributed to the synergistic effect between NiCo₂S₄ nanoparticles and RGO, in which RGO can provide conductive channels and serve as an ideal support matrix. The facile synthesis and the remarkable capacitive performance of the NiCo₂S₄/RGO hybrid make it a promising candidate for electrode materials in electrochemical energy conversion/storage devices.