Porous polypyrrole clusters prepared by electropolymerization for a high performance supercapacitor

Different nanostructures (Ns), such as nanobelts, nanobricks and nanosheets, of polypyrrole (PPy) were successfully fabricated on stainless steel substrates by simply varying the scan rate of deposition in the potentiodynamic mode. These PPy Ns were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and surface area measurement. The XRD analysis showed the formation of amorphous PPy thin films, and the FTIR studies confirmed characteristic chemical bonding in the PPy materials. SEM images depicted that a high scan rate of deposition can form multilayer nanosheets with high porosity leading to a system with excellent processability. The PPy nanosheets possess a higher Brunauer-Emmett-Teller (BET) surface area of 37.1 m(2) g(-1) than PPy nanobelts and nanobricks. The supercapacitive performances of different PPy Ns were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge techniques in 0.5 M H2SO4. A maximum specific capacitance of 586 F g(-1) was obtained for multilayer nanosheets at a scan rate of 2 mV s(-1). In addition, impedance measurements of the different Ns of PPy electrodes were performed suggesting that the PPy electrodes with multilayer nanosheets are promising materials for the next generation high performance electrochemical supercapacitors.