Synthesis and electrochemical performance of well-defined flake-shaped sulfonated graphene/polypyrrole composites via facile in situ doping polymerization

Sulfonated graphene (SG) prepared by anchoring the organic sulfonic acid on the surface of the graphene nanosheets was used as the unique dopant for the in situ chemical oxidative polymerization of pyrrole for the well-defined flake-shaped sulfonated graphene/polypyrrole (SG/PPy) composites. The structures of these composites with the different feeding ratio of SG had been characterized by TEM, SEM, FTIR, Raman and XRD techniques. The SG sheets were homogeneously coated on both surfaces with PPy. Themogravimetric analysis revealed a significantly enhanced thermal stability. The SG/PPy composite S-4 (50 wt% SG) with the well-defined flake-shaped morphology exhibited the highest electrical conductivity of 50 S cm(-1), while the SG/PPy composite S-2 (30 wt% SG) possessed the highest specific capacitance (261.0 Fg(-1)) at the charge-discharge current density of 1 Ag-1 in 1.0 M H2SO4 electrolyte. About 87% of its original specific capacitance could be remained after 1000 cycles. The excellent capacitance behavior also was found in electrochemical impedance spectroscopy. It makes the SG/PPy composite a promising electrode material for high performance supercapacitors. (C) 2013 Elsevier Ltd. All rights reserved.