Redox properties of the ferricyanide ion on electrodes coated with layer-by-layer thin films composed of polysaccharide and poly(allylamine)

Takio Noguchi, Jun Ichi Anzai

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

Polyelectrolyte multilayer thin films were prepared by an alternate deposition of poly(allylamine hydrochloride) (PAH) and anionic polysaccharides {carboxymethylcellulose (CMC) and alginic acid (AGA)} on the surface of a gold (Au) disk electrode, and the binding of ferricyanide [Fe(CN)6] 3- and hexaammine ruthenium ions [Ru(NH3) 6]3+ to the films was evaluated. Poly(acrylic acid) (PAA) was also employed as a reference polyanion bearing carboxylate side chains. A quartz-crystal microbalance study showed that PAH-CMC and PAH-AGA multilayer films grow exponentially as the number of depositions increases. The thicknesses of five bilayers of (PAH-CMC)5 and (PAH-AGA)5 films were estimated to be 150 ± 20 and 90 ± 15 nm, respectively, in the dry state. The PAH/polysaccharide multilayer film-coated Au electrodes exhibited a redox response to the [Fe(CN)6]3- ion dissolved in solution, irrespective of the sign of the surface charge of the film, suggesting the high permeability of the films to the [Fe(CN)6]3- ion. In contrast, the PAH-PAA film-coated Au electrodes exhibited a redox response only when the outermost surface of the film was covered with a positively charged PAH layer. However, the permeation of the [Ru(NH 3)6]3+ cation was severely suppressed for all of the multilayer films. It was possible to confine the [Fe(CN) 6]3- ion in the films by immersing the film-coated electrodes in a 1 mM [Fe(CN)6]3- solution for 15 min. Thus, the [Fe(CN)6]3--confined electrodes exhibited a cyclic voltammetric response in the [Fe(CN)6]3- ion-free buffer solution. The loading of the [Fe(CN)6]3- ion in the films was higher when the surface charge of the film was positive and increased with increasing film thickness. It was also found that the [Fe(CN) 6]3- ion confined in the films serves as an electrocatalyst that oxidizes ascorbic acid in solution.

Original languageEnglish
Pages (from-to)2870-2875
Number of pages6
JournalLangmuir
Volume22
Issue number6
DOIs
Publication statusPublished - 2006 Mar 14

ASJC Scopus subject areas

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

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