The formation and reduction of anodic films on electrodeposited ruthenium

The formation and reduction of anodic films on bright ruthenium was investigated using substrates prepared by electrodeposition onto gold-plated platinum from a commercial ruthenium bath operated at 70°C. Anodic films formed on the ruthenium may be reduced by maintaining the electrode at potentials below 0.2 V. The reduction behaviour was markedly affected by the anodization potential and, at short times, by the period of anodization. The bell-shaped cathodic current-time curves observed with films produced at potentials in the region of 1.2 V, suggest that the process in this case involves nucleation of reduction centres on a relatively stable surface layer. The influence of potential, time, and both the concentration and nature of the electrolyte on the extent of anodic film formation was investigated. The results are discussed in terms of the formation of stable phase oxides in the relatively thick anodic film produced on the ruthenium surface.