Preparation and electrochemical properties of modified electrodes with Keggin-type silicotungstates and PEDOT

Hybrid organic/inorganic films composed of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT), with Keggin type polyoxotungstates [SiW12O40]4−, [SiW11O39]8−, [SiW11FeIII(H2O)O39]5− or [SiW11CoII(H2O)O39]6− were synthesized by electrochemical polymerization in aqueous solution on the surface of glassy carbon electrodes. Cyclic voltammetry showed that the electrochemical behaviour of the polyoxometalates in the films was very similar to those in solution, and gave evidence of high electrochemical stability. Electrochemical impedance spectroscopy revealed that the charge transfer resistance increased with increasing pH and with more negative potentials. These modified electrodes were found to be very stable and could be used for at least 1 month without significant alterations.