Amperometric chemical sensors using microheterogeneous systems

Abstract

A theoretical model describing heterogeneous redox catalysis at metal oxide–Nafion composite modified electrodes is presented. The metal oxide particles are assumed to be dispersed in a homogeneous manner within the polymeric Nafion matrix. The composite material is deposited on the surface of a support electrode in the form of a thin film. The surface of each oxide particle is assumed to be catalytically active. The interaction between substrate and the catalytically active oxymetal surface group is assumed to follow Michaelis–Menten kinetics. The transport and kinetics of the substrate within the polymer film is examined and various limiting expressions for the reaction flux are proposed. The theoretical predictions are compared with experimental results obtained for the electro-oxidation of catechol at RuO₂–Nafion composite electrodes.