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Electrodes of Poly(N-methyl pyrrole)/Au and Poly(m-aminobenzene sulfonic acid)-Functionalized Multiwalled Carbon Nanotubes for Supercapacitor Applications

Authors

  • B. Narsimha Reddy,

    1. Department of Chemistry, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yedduaram 502205, Andhra Pradesh (India), Fax: (+91) 40-23016003
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  • Naresh Billa,

    1. Department of Chemistry, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yedduaram 502205, Andhra Pradesh (India), Fax: (+91) 40-23016003
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  • Dr. Melepurath Deepa

    Corresponding author
    1. Department of Chemistry, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yedduaram 502205, Andhra Pradesh (India), Fax: (+91) 40-23016003
    • Department of Chemistry, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yedduaram 502205, Andhra Pradesh (India), Fax: (+91) 40-23016003
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Abstract

An assembly of poly(N-methyl pyrrole) (PMP) doped with poly(3-styrene sulfonate) with embedded Au nanoparticles (PMP/Au) was grown by electropolymerization of the monomer (MP) followed by adsorption of a Au colloid. Multiwalled carbon nanotubes were functionalized with poly(m-aminobenzene sulfonic acid) (MWCNT/PABS) and deposited electrophoretically over conducting substrates. X-ray diffraction (XRD) and Raman studies confirmed the successful functionalization of the MWCNTs by PABS. A new asymmetric supercapacitor design incorporating PMP/Au and MWCNT/PABS as electrodes was implemented for the first time, and the cell delivered a reversible specific capacitance of 967 F g−1 and a maximum energy density of 174 Wh Kg−1, which was superior to a PMP-MWCNT/PABS cell (167 F g−1) and higher than many reported capacitances of poly(pyrrole)-based supercapacitors. The PMP/Au electrode outperformed pristine PMP, graphite, and MWCNT/PABS electrodes in a study of different symmetric and asymmetric cells employing these electrodes. Scanning spreading resistance microscopy (SSRM) and conducting atomic force microscopy (C-AFM) showed a lower spreading resistance and a larger nanoscale electronic conductivity for the PMP/Au electrode than for the pristine PMP electrode; these attributes allow unhindered charge transport both in the radial direction and across the cross-section of the PMP/Au electrode. The facile electron propagation in the PMP/Au electrode, enabled by the presence of localized conducting domains of Au nanoparticles implanted in the PMP electrode, effectively translates into an enhanced specific capacitance of PMP/Au-based cells relative to PMP. The results demonstrate that asymmetrically designed cells offer an exciting way to boost the overall performance of supercapacitors.

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