Coupled Redox and pH Potentiometric Responses of Electrodes Coated with Polypyrrole

Krzysztof Maksymiuk, Johan Bobacka, Ari Ivaska, Andrzej Lewenstam

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)

Abstract

The coupled influence of solution acidity and redox electrolytes on the open-circuit potentials of polypyrrole-modified electrodes was studied by recording the potential vs. time dependencies. It was observed that doping anions affect the relative rate of the responses resulting from pH influence (pH response) and from the presence of a redox couple in the solution, such as Fe(III)/Fe(II) or Fe(CN)(6)(3-/4-) (redox response). Separation of the pH and redox responses was possible for polypyrrole doped with large organic anions of weak acids (Tiron, sulphosalicylic acid, Indigo Carmine). In such cases, a very fast pH response was recorded after which the polymer potential relaxed to the solution redox potential in each case. The final stable potential was determined entirely by the potential of the redox couple in solution. The final potential was pH-independent unless the redox potential was influenced by solution acidity. The solution pH determines only the shape of the potential vs. the time dependence, e.g. much faster responses were observed for solutions with a higher H* concentration.
Original languageUndefined/Unknown
Pages (from-to)1339–1360
Number of pages22
JournalAnalytical Letters
Volume33
Issue number7
DOIs
Publication statusPublished - 2000
MoE publication typeA1 Journal article-refereed

Keywords

  • open-circuit potentials
  • pH response
  • redox response

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