Preparation and capacitance properties of graphene-polypyrrole nanotube hybrid

A graphene-polypyrrole nanotube hybrid is fabricated by chemical hybridization method. Scanning electron microscopy, transmission electron microscopy, fourier-transmission infrared spectroscopy, X-ray photoelectron spectroscopy and electrochemical workstation are used out to characterize the morphology, structure and properties of graphene-polypyrrole nanotube hybrid. The electron microscopy images show that graphene sheets and polypyrrole nanotubes distribute well in the hybrid. The results of spectroscopy analysis confirm the existence of amide group which connects graphene and polypyrrole nanotube in the hybrid. The specific capacitance of the hybrid is 1368 F · g^-1 at a current density of 0.3 A · g^-1 as well as the specific capacitance of 759 F · g^-1 at a current density of 1.5 A · g^-1. In long-term cyclic voltammetry tests, after 1000 cycles, the preserved specific capacitance of the hybrid is 85.5% of its initial specific capacitance, demonstrating a good electrochemical stability. The Nyquist plot of the graphene-polypyrrole nanotube hybrid reveals its good pseudocapacitance performance.