Changes in the iron(III)/iron(II) redox process at a gold microelectrode in liquid and frozen low temperature perchloric and sulfuric acid electrolyte media

A. M. Bond, M. Švestka

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Abstract

Voltammetric studies of the Fe3+ + e- ⇌ Fe2+ electrode process have been undertaken at a 2.5 μm radius gold disk microelectrode in liquid and frozen perchloric and sulfuric acid electrolyte. Studies when the electrolyte contains Fe3+, Fe2+ or mixtures of Fe3+and Fe3+ reveal that the redox mechanism changes from diffusion control in the liquid state at ambient temperatures to a surface confined pathway in frozen media at low temperatures with the reversible potential for both electron transfer pathways being essentially the same. In perchloric acid electrolyte, over the temperature range 0 to -60°C, where ice is present, both mass transport pathways are observed simultaneously. The rate of electron transfer in the low temperature studies in acidic electrolyte is considerably enhanced by the presence of sulfate ions, as is the case in the liquid state at ambient temperatures.

Original languageEnglish
Pages (from-to)139-154
Number of pages16
JournalJournal of Electroanalytical Chemistry
Volume301
Issue number1-2
DOIs
Publication statusPublished - 25 Feb 1991

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