Grafting of the carbon allotropes and polypyrrole via a Kevlar-type organic linker: the correlation of carbon structure/morphology with electrochemistry of the composite electrode

• Published in: Materials for renewable and sustainable energy 2017-02, Vol.6 (1), p.1-15, Article 1
• Main Authors: Radtke, Mariusz, Ignaszak, Anna
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Materials Science; Original Paper; Renewable and Green Energy
• ISSN: 2194-1459; 2194-1467
• DOI: 10.1007/s40243-016-0085-x

This study validates three carbon allotropes, such as carbon nanotubes, graphene and carbon nanohorns that are covalently bound via a Kevlar-type linker (amide-bound aryl) with polypyrrole. In the proposed synthesis, the linker moiety is formed onto the carbon surface via combined electrochemical and chemical reactions and the polymer is attached during the final phase. Overall, the highest specific capacitance (~350 F/g) and thermal and electrochemical stability were observed for the MWCNT-based system, followed by Nanohorn- g -PPy (- g - stands for grafted) and the least stable with the smallest capacitance for the Graphene-based composite. The MWCNT-grafted material demonstrated a non-continuous and very thin polypyrrole coating onto the carbon surface. These structures are rigid, stable and reveal good accessibility of ions towards both the carbon and polymer. This system showed also the highest diffusion coefficient for the ion doping owing to the polymer effective diffusion length. The fast degradation of Graphene- g -PPy is associated with the carbon morphology and its high activity towards electrochemical oxygen reduction due to the presence of catalytic sp 2 carbon atoms at the edges of the graphene. The presented work highlights an effect of carbon morphology in designing chemically grafted components for ultra-capacitor electrodes. Graphical abstract