Electrochemical behavior of poly(3,4-ethylenedioxy)thiophene doped with hexacyanoferrate anions in different electrolyte media

Abstract

This paper describes in detail the electrochemical properties of potentiodynamically synthesized poly(3,4-ethylenedioxy)thiophene (PEDOTh) modified by the entrapment of hexacyanoferrate anions (Fe(CN)63–). Cyclic voltammetric data clearly shows that during polymer redox conversion/immobilized anion reduction and re-oxidation, charge compensation occurs at the expenses of the insertion–deinsertion of appropriate cations from solution. In aqueous electrolyte mainly protons are involved whereas in organic media the process requires small highly mobile ions such as lithium. PEDOTh/Pt and PEDOTh/Fe(CN)63–/Pt have been used for the detection of ascorbic acid (AA) in mixed medium (0.1 M TBAPF6 in acetonitrile + 8% H2O). Compared to that of bare platinum electrode, the analyte oxidation peak potential occurs at significant less positive values at both modified electrodes, revealing their good electrocatalytic activity. For the polymer incorporating ferricyanide ion, the observed decrease in the AA oxidation onset potential along with the fading away of Fe(CN)63– reduction signal, supports a mechanism taking into account the mediator character of the embedded anion.