Transition metal ion-substituted polyoxometalates entrapped into polypyrrole as electrochemical sensor for hydrogen peroxide

A conducting polymer was used for the immobilization of various transition metal ion-substituted Dawson-type polyoxometalates (POMs) onto glassy carbon electrodes. Voltammetric responses of films of different thicknesses were stable within the pH domain 2-7 and reveal redox processes associated with 10 the conducting polymer, the entrapped POMs and incorporated metal ions. The resulting POM doped polypyrrole films were found to be extremely stable towards redox switching between the various redox states associated with the incorporated POM. An amperometric sensor for hydrogen peroxide detection based upon the POM doped polymer films was investigated. The detection limits were 0.3 and 0.6 uM, for the Cu2+- and Fe3+-substituted POM-doped polypyrrole films respectively, with a linear region from 15 0.1 up to 2mM H2O2. Surface characterization of the polymer films was carried out using atomic force microscopy, x-ray photoelectron spectroscopy and scanning electron microscopy.