CHARACTERIZATION OF DSA-TYPE OXYGEN EVOLVING ELECTRODES - CHOICE OF A COATING

In the search for a DSA(R) -type electrode for oxygen evolution in acidic solutions, nine binary coatings with IrO2, RuO2, Pt as conducting component, and TiO2, ZrO2, Ta2O5 as inert oxides, have been deposited on titanium, examined for their microstructural properties and tested for their electrocatalytic activity and anodic stability. Electrochemical "true" surfaces of the coatings were found to be dependent on structure and morphology: the mixtures that form a solid solution (RuO2-TiO2), or allow limited miscibility (IrO2-TiO2), show the lowest dispersion of active material. Differences in service lives, were attributed to differences in wear mechanism of the electrodes. It was found that Ti/IrO2 (70 mol%)-Ta2O5 (30 mol%) is by far the best electrode.