Proton transfer equilibria at electroactive TCNQ polymer film electrodes

Gyorgy Inzelt, James Q. Chambers

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Polymeric tetracyanoquinodimethane (TCNQ) film electrodes in contact with aqueous solutions of different pH and electrolyte concentrations were studied using cyclic voltammetry and potential step methods. The effect of temperature and D2O solvent was also investigated. The extent of development and E 1 2 values of the voltammetric wave for the TCNQ.-/TCNQH-, TCNQH2 process were used to follow film pH values and protonation equilibria. In contact with unbuffered solutions, slow reduction of the film is attributed to mass transport controlled exclusion of hydroxide co-ions from the film. As a result, the charge transport rate for the TCNQ.-/TCNQH- process is two orders of magnitude higher for the oxidation than for the reduction step. In contact with buffer solutions, concentration-dependent pH gradients between the polymer film and solution exist as a result of the extensive consumption of protons by the high density of film redox sites during reduction or the release of protons during oxidation. The film pH and buffer capacity are also affected by Donnan exclusion of buffer co-ions.

Original languageEnglish
Pages (from-to)265-275
Number of pages11
JournalJournal of Electroanalytical Chemistry
Volume266
Issue number2
DOIs
Publication statusPublished - Jul 25 1989

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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