The Electroactive Integrated Optical Waveguide: Ultrasensitive Spectroelectrochemistry of Submonolayer Adsorbates

Darren R. Dunphy, Sergio B. Mendes, S. Scott Saavedra, Neal R. Armstrong

Research output: Contribution to journalArticle

67 Scopus citations

Abstract

Highly sensitive spectroelectrochemistry of adsorbed films on ITO is demonstrated with the electroactive integrated optical waveguide (EA-IOW). The EA-IOW, a single-mode planar waveguide coated with an ITO layer, is ∼104-fold more sensitive to changes in absorbance occurring during electrochemical events versus a single-pass transmission spectroelectrochemical experiment, as demonstrated by reduction of surface-adsorbed methylene blue. Furthermore, the EA-IOW is selective to near-surface events, as it is relatively insensitive to absorbance by solutions of dissolved chromophores at <1 mM. The EA-IOW is also used to monitor the formation of Prussian Blue during the reduction of ferricyanide, an event that is not easily followed using current-detected cyclic voltammetry, due to interfering faradaic and non-faradaic electrochemical events. The optical background of the EA-IOW is potential-dependent and is explained by ion diffusion into the ITO and by voltage-dependent changes in optical constants for the material. Finally, the high sensitivity of the EA-IOW (relative to other evanescent-field-based spectroelectrochemical techniques) is discussed in terms of its design.

Original languageEnglish (US)
Pages (from-to)3086-3094
Number of pages9
JournalAnalytical chemistry
Volume69
Issue number15
DOIs
StatePublished - Aug 1 1997

ASJC Scopus subject areas

  • Analytical Chemistry

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