Design and synthesis of three-dimensional CoNi2S4@MoS2@rGO nanocomposites and its application in electrochemical supercapacitors

A spongy nanostructure of graphene oxide was synthesized to enhance the porosity and surface area. Then, CoNi2S4 and MoS2 nanocomposites were fixed on the porous graphene oxide to increase the capacity and improve its performance as a substrate. Finally, they were integrated to produce the final nanocomposite. The presence of metal sulfides, as electroactive materials, promises a synergistic effect for use in supercapacitors by accelerating ion/electron diffusion rates and enlarging the active sites. The synthesized spongy nanocomposite (CoNi2S4 @MoS2 @rGO) was characterized by various techniques, including Raman spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. The results of our study showed that the spongy nanocomposite has a specific capacitance of 3268 F g−1 at 1.0 A g−1 in a 3.0 M KOH solution. In addition, it can sustain 93.6% stability of its initial capacity after 3000 consecutive charge-discharge cycles at a current density of 10.0 A g−1. Also, the optimal potential window (from zero to 1.40 V) was determined in the asymmetric configuration of this electrode. The energy density of 41 Wh kg−1 and power density of 700 W kg−1 indicate the applicability of this electrode in supercapacitor application.