Characterization of ferrocene-modified electrode using electrochemical surface forces apparatus

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Abstract

A electrochemical surface forces apparatus (EC-SFA) was employed to measure the interactions between gold electrodes modified with self-assembled monolayers of ferrocene alkyl thiol (Fc-SAM) and oxidized ferrocene (ferrocenium cation, Fc+-SAM) in a 1 mM aqueous electrolyte. The double-layer repulsion in both cases of the Fc-SAM and Fc+-SAM electrodes was observed. The surface charge density (σ) evaluated from the double-layer repulsions between the Fc+-SAM electrodes in 1 mM aqueous KClO 4 was 0.0027 C/m2, which was 2.5 times greater than that of the Fc-SAM, at 0.0011 C/m2. The σ values of the Fc +-SAM were evaluated for various counteranions using the same method, which were 0.0048, 0.0040, and 0.0104 C/m2 for NO3 -, SO42-, and CF3SO3 -, respectively. The degrees of dissociation (αd) between the ferrocenium cation and these counteranions were obtained from σ and the density of the ferrocenium on the electrode. The αd value of CF3SO3-, 4.1%, was the highest, followed in the order, SO42- > NO 3- > ClO4-, indicating that most of the positive charges of the ferrocenium cation were compensated by formation of an ion pair with counteranions.

Original languageEnglish
Pages (from-to)7093-7097
Number of pages5
JournalLangmuir
Volume30
Issue number24
DOIs
Publication statusPublished - 2014 Jun 24

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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