Effect on durability and electrochemical response of the addition of a non-noble transition metal in mixed ruthenium and manganese oxide thin-film electrodes

Mixed metal oxide (MMOx) thin films-based electrodes have been widely used in the treatment of polluted solutions. To limit costs while exploring new electrocatalytic potentials, novel mixtures are being proposed. In this paper, the electrochemical behavior of thin films obtained by co-deposition of Ruthenium, Manganese, and a third transition metal among Copper, Iron, and Cobalt was investigated with the scope of finding optimal compositions and long stability for applications as the anodes in environmental treatments. The binary and ternary oxides coated electrodes were prepared by thermal decomposition on titanium foils from alcoholic solutions. The morphological properties of the thin films were analyzed through scanning electron microscopy (SEM) while the electrochemical performance was evaluated by potentiodynamic polarization curves and cyclic voltammetry (CV). The service time was assessed by accelerated life tests. The results show that the combination of Ruthenium with one or two different metals results in evident modifications of the morphology, both kinetic and thermodynamic electrochemical properties as well as the service lifetime. In particular, a combination of Iron and Manganese was to be excluded because of the poor solubility which affected both the coating homogeneity and electrochemical response. The Cobalt-containing electrodes outperformed the others in terms of stability. The addition of Copper implied a reduced susceptibility to corrosion and higher charge storage.