Enhanced capacitance and stability of p-toluenesulfonate doped polypyrrole/carbon composite for electrode application in electrochemical capacitors

Polypyrrole/carbon (PPy/C) composites have been synthesized using varying concentration of p-toluenesulfonate (pTS) dopant by surface initiated in-situ chemical oxidative polymerization with the purpose to develop an electrode material for supercapacitors. The influence of pTS on the structure of the composite is observed through Fourier transform infrared (FT-IR) and Raman spectroscopy while the morphological features have been examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The dc conductivity shows direct correlation with pTS concentration and follows Mott's three dimensional variable range hopping (3D-VRH) charge transport. The performance of PPy/C composite electrode for charge storage has been analyzed using electrochemical tools such as cyclic voltammetry and electrochemical impedance spectroscopy. The maximum specific capacitance similar to 395 F g(-1) in 0.5 M Na2SO4 aqueous solution with significant stability (similar to 500 cycles) is obtained for the material synthesized using equimolar concentration (0.1 M) of pTS to pyrrole. (C) 2013 Elsevier B.V. All rights reserved.