Modified carbon nanoparticle-chitosan film electrodes: Physisorption versus chemisorption

Liza Rassaei, Mika Sillanpää, Frank Marken

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

Surface functionalised carbon nanoparticles of ca. 8 nm diameter co-assemble with chitosan into stable thin film electrodes at glassy carbon surfaces. Robust electrodes for application in sensing or electrocatalysis are obtained in a simple solvent evaporation process. The ratio of chitosan binder backbone to carbon nanoparticle conductor determines the properties of the resulting films. Chitosan (a poly-d-glucosamine) has a dual effect (i) as the binder for the mesoporous carbon composite structure and (ii) as binding site for redox active probes. Physisorption due to the positively charged ammonium group (pKA ≈ 6.5) occurs, for example, with anionic indigo carmine (a reversible 2e--2H+ reduction system in aqueous media). Chemisorption at the amine functionalities is demonstrated with 2-bromo-methyl-anthraquinone in acetonitrile (resulting in a reversible 2e--2H+ anthraquinone reduction system in aqueous media). Redox processes within the carbon nanoparticle-chitosan films are studied and at sufficiently high scan rates diffusion of protons (buffer concentration depended) is shown to be rate limiting. The chemisorption process provides a much more stable interfacial redox system with a characteristic and stable pH response over a pH 2-12 range. Chemisorption and physisorption can be employed simultaneously in a complementary binding process.

Original languageEnglish
Pages (from-to)5732-5738
Number of pages7
JournalElectrochimica Acta
Volume53
Issue number19
DOIs
Publication statusPublished - 1 Aug 2008
Externally publishedYes

Keywords

  • Carbon nanoparticles
  • Chemisorption
  • Chitosan
  • Mesoporous films
  • Physisorption
  • Sensors
  • Voltammetry

ASJC Scopus subject areas

  • General Chemical Engineering
  • Electrochemistry

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