Insights into the surface and redox properties of single-walled carbon nanotube-cobalt(II) tetra-aminophthalocyanine self-assembled on gold electrode

Kenneth I. Ozoemena, Tebello Nyokong, Duduzile Nkosi, Isabelle Chambrier, Michael J. Cook

Research output: Contribution to journalArticlepeer-review

88 Citations (Scopus)

Abstract

This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3-/4- as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (Ret) and much higher (∼10 times) apparent electron-transfer rate constant (kapp) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.

Original languageEnglish
Pages (from-to)4132-4143
Number of pages12
JournalElectrochimica Acta
Volume52
Issue number12
DOIs
Publication statusPublished - 10 Mar 2007
Externally publishedYes

Keywords

  • AFM
  • Cobalt(II)tetra-aminophthalocyanine
  • Cyclic voltammetry
  • Dopamine
  • Impedance spectroscopy
  • Self-assembled monolayer
  • Single-walled carbon nanotube
  • XPS

ASJC Scopus subject areas

  • General Chemical Engineering
  • Electrochemistry

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