Polyaniline/reduced graphene oxide-cobalt sulfide ternary composite for high-performance supercapacitors

In this work, a novel ternary composite consisting of polyaniline-reduced graphene oxide-cobalt sulfide (PANI-rGO-CoS) was prepared by a two-step process. In the first step, a simple and cost effective hydrothermal route was employed for the synthesis of cubic cobalt sulfide (CoS) on the graphene oxide sheets. In the second step, the polyaniline nanorods were grown on the surface of rGO-CoS sheets via in situ aniline chemical polymerization which was synergistically attached to the graphene surface. The structure and morphology of resulting ternary composite were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and field-emission scanning electron microscopy. The obtained cubic CoS which was incorporated in ternary composite exhibited significant increase in specific capacitance compared to binary polyaniline-reduced graphene oxide (PANI-rGO) composite. Electrochemical measurements demonstrated that the specific capacitance of the ternary PANI-rGO-CoS composite was 431 F g(-1) at the current density of 0.5 A g(-1) in 1 M H2SO4 solution, which was significantly higher than that of the binary PANI-rGO composite (276 F g(-1)). In addition, the composite displayed good cycle stability retaining 90.1% of their original specific capacitance after 1000 charge-discharge cycles.