Graphene covalently functionalized with poly(p-phenylenediamine) as high performance electrode material for supercapacitors

Abstract

A reduced graphene oxide–poly(p-phenylenediamine) (RGO–PPD) composite was prepared from p-phenylenediamine (PD) and chlorinated graphene oxide (GO–COCl) sheets through amidation and polymerization processes. Then the RGO–PPD composite was characterized by using scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The results show that PPD nanoparticles were wrapped within or on the surface of graphene sheets uniformly. The RGO–PPD composite displayed a layered-stacking structure and had a large surface area (674.22 m2 g−1) and a high pore volume (0.43 cm3 g−1). Capacitive properties of the RGO–PPD composite were studied using cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) in an electrolyte of 0.5 M H2SO4 aqueous solution. The RGO–PPD exhibits a high specific capacitance of 347 F g−1 at a discharge rate of 1 A g−1 and excellent cycling stability with 90.1% of its initial capacitance at a large current density of 10 A g−1 after 1000 charge/discharge cycles. The energy density and specific power density of the present supercapacitor are 48.2 W h kg−1 and 1.0 kW kg−1, respectively. The results suggest that the RGO–PPD is a promising material for high-performance supercapacitor applications.