Unexpected redox rectification by an electrochemically prepared iridium oxide electrode/aqueous acid interface

Christopher S. Johnson, Joseph T. Hupp

Research output: Contribution to journalArticle

2 Citations (Scopus)


In highly acidic aqueous solutions, electrochemically prepared iridium oxide films behave as steady-state insulators and transient rectifiers towards the Ru(NH3)63+/2+ redox couple. In less acidic solutions the films show only partial transient rectification or else fully reversible transient behavior, together with Koutecky-Levich-type steady-state behavior. Experimental studies, as a function of Ru(NH3)63+ concentration, solution pH, film thickness, voltammetric sweep rate and electrode rotation rate, show that these unusual phenomena are related to: (1) transient uptake of Ru(NH3)63+, apparently in place of H+, during film-based Ir(IV/III) cycling; (2) Donnan exclusion of Ru(NH3)63+ from the reduced film under steady-state conditions; and/or (3) film-based diffusional inhibition of Ru(NH3)63+ reduction.

Original languageEnglish
Pages (from-to)351-362
Number of pages12
JournalJournal of Electroanalytical Chemistry
Issue number1-2
Publication statusPublished - Feb 15 1993


ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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