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Abstract:
Conducting polymers can act as electrodes oxidizing/reducing redox systems in electrolytes. The mechanism of such heterogeneous charge-transfer reactions is discussed on the basis of energetic considerations involving the band model of the polymer, polarons/bipolarons, and the electronic states of the redox system in the electrolyte. The kinetics of the electrochemical reaction is shown to depend strongly on the standard potential, E0, of the redox system. When E0 corresponds to the oxidized (conducting) state of the polymer, the charge-transfer reaction can proceed effectively. When E0 corresponds to the reduced (insulating) state of the polymer, the charge-transfer reaction is inhibited. The concepts are supported by electrochemical experiments with poly (N-methylpyrrole) films, and Fe(CN)63−/4− and Eu3+/2+ as depolarizers.
