Interfacial/in situ oxidative polymn. of polypyrrole in the presence of functionalized graphene sheets produces high-quality composites for supercapacitors, as analyzed by electrochem. impedance spectroscopy and cyclic voltammetry anal. The synergistic interaction induced by the growth of p-type polypyrrole on the surface of neg. charged carboxylate functionalized graphene sheets results in higher storage capacity than graphene-only or polymer-only films. The high cond. of p-doped polypyrrole and high surface area of graphene promote high charge accumulation in capacitors. The authors report the optimization of the relative concns. of carboxylate functionalized graphene in the polypyrrole matrix to maximize the compn.'s capacitance to 277.8 F/g. [on SciFinder(R)]