Composite films of iron(III) hexacyanoferrate and poly(3,4-ethylenedioxythiophene): electrosynthesis and properties

The details of a potentiostatic preparation method for a composite of iron( III) hexacyanoferrate and poly(3,4-ethylenedioxythiophene) on a platinum el ectrode are reported. The heterogeneous electron transfer processes involvi ng the composite and its stability are examined in aqueous and acetonitrile solutions. Cyclic voltammetrical studies show that in aqueous solution pol y(3,4-ethylenedioxythiophene) is in its neutral state (non oxidised state) in the potential range where iron(III) hexacyanoferrate is electroactive. O n the other hand, in acetonitrile solution, we show that iron(III) hexacyan oferrate is not electroactive. Thus, the faradaic response of the composite is due only to the poly(3,4-ethylenedioxythiophene) in this organic medium . This behaviour allows us to study separately the electrochemical behaviou r of each part of the composite in the two solvents. A cooperative effect ( synergy) is observed within the composite. This is reflected by the increas e of the faradaic and the capacitive responses of the poly(3,4-ethylenediox ythiophene) in acetonitrile solution in the presence of iron(III) hexacyano ferrate. Moreover, the stability of the iron(III) hexacyanoferrate in the c omposite material is enhanced in aqueous solution. (C) 2000 Elsevier Scienc e S.A. All rights reserved.