Characterisation of doped polypyrrole/manganese oxide nanocomposite for supercapacitor electrodes

P-toluenesulfonic acid (TSA) doped polypyrrole (PPy) binary nanocomposite and MnO2/PPy/TSA ternary nanocomposite were prepared by chemical oxidative polymerization. The chemical compositions of nanocomposites were characterised by infrared spectrometry and energy dispersive spectroscopy. Micrographs and BET isotherm measurements showed that the particle and the pore size of the ternary nanocomposite are much smaller than those of the binary one. Electrochemical measurements showed that the ternary nanocomposite electrode exhibited a higher specific capacitance of ∼376 F g−1 at 3 mA cm−2 and better cycling stability in 0.5 M Na2SO4 solution than the binary one, which is attributed to that the dispersed MnO2 particles adhered to PPy chains increase the specific surface area of the ternary nanocomposite and retard the structural deterioration of PPy backbones during charge–discharge cycling process. Long cyclic measurements showed that the specific capacitance of ternary composite can retain 90% of its initial value over 500 charge–discharge cycles in the potential range of −0.1 to 0.9 V vs. SCE. Nevertheless, the dispersed MnO2 could reduce the rate capability and conductivity of the ternary composite.