Electrochemical Characterisation of Ni^II-Crown-Type Polyoxometalate-Doped Polypyrrole Films for the Catalytic Reduction of Bromate in Water

The nickel substituted (Ni₄[(P₈W₄₈O₁₈₄)(WO₂)]^28–, crown type polyoxometalate was electrochemically polymerised with conducting polymer pyrrole for the electrocatalytic reduction of bromate in water. The immobilized films of different thickness were characterised by electrochemical and surface based techniques. The resulting films were found to be extremely stable towards redox switching between the various redox states associated with the incorporated POM. This system was found to effectively electrocatalyse the reduction of bromate in water without the interference of other common anions. The detection limit was found to be 0.2 µm, with a linear region from 0.1 mm up to 2 mm bromate. The resulting POM doped polypyrrole films were found to be highly conductive by AC impedance. Surface characterization of the polymer films was carried out by using X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy.