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Electrodes of Poly( N ‐methyl pyrrole)/Au and Poly( m ‐aminobenzene sulfonic acid)‐Functionalized Multiwalled Carbon Nanotubes for Supercapacitor Applications
Author(s) -
Narsimha Reddy B.,
Billa Naresh,
Deepa Melepurath
Publication year - 2012
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201200140
Subject(s) - supercapacitor , electrode , materials science , sulfonic acid , electrochemistry , nanoparticle , chemical engineering , carbon nanotube , nanotechnology , polymer chemistry , chemistry , engineering
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.