Oxygen Evolution and Corrosion on Ruthenium‐Iridium Alloys

The initial stages of evolution and anodic corrosion on ruthenium‐iridium alloys have been investigated in using voltammetry and x‐ray photoelectron spectroscopy (XPS). The alloys were prepared by mixed RF sputtering onto glass substrates. Cyclic voltammetry shows that the corrosion of the Ru component is significantly reduced with increasing Ir content. Simultaneously, the activity for evolution decreases as a consequence of increased Tafel slope and overpotential. The XPS studies show that the reduced corrosion of Ru is paralleled by an increased tendency to oxide formation of the Ir component. The stabilization of Ru by admixtures of Ir is assigned to the formation of a protective oxide layer with increased Ir content. In addition, a shift of redox potentials for oxide formation is observed.