Graphene/poly(ortho-phenylenediamine) nanocomposite material for electrochemical supercapacitor

Reduced graphene oxide was synthesized by simple chemical processing of graphite. Electron microscopy investigations of synthesized graphene showed slightly folded transparent sheets with a few square micrometers dimension. Poly(ortho-phenylenediamine)/graphene/Pt electrode was electrochemically fabricated in a 2.0-M H₂SO₄ solution by means of multiple potential cycling. Due to the catalytic effect of graphene on the oxidative electropolymerization of ortho-phenylenediamine, the ortho-phenylenediamine/graphene (PoPD/GR) nanocomposite showed greatly enhanced electrical properties and excellent capacitive behavior. Electrochemical impedance spectroscopy, galvanostatic charge/discharge curves, and voltammetric investigations revealed that PoPD/GR nanocomposite represented good capacitive behavior with a specific capacitance as high as 308.3 F g^?1 at 0.1 A g^?1. It is almost three times higher than that of pure graphene (111.7 F g^?1). In addition, the nanocomposite electrode retained more than 99 % of the initial capacity after 1,500 cycles at a current density of 1 A g^?1.