In-situ identification of RuO₄ as the corrosion product during oxygen evolution on ruthenium in acid media

The corrosion of ruthenium during oxygen evolution in 0.5 M H₂SO₄ was investigated using cyclic voltammetry, the rotating ring-disc electrode technique and differential reflectance spectroscopy. Cyclic voltammetric curves exhibit a distinct reduction peak at ∼ +0.80 V vs. SCE in the negative scan provided the positive limit is extended beyond ∼ +1.2 V vs. SCE. The use of in-situ reflectance spectroscopy allows the identification of RuO₄ as the main, if not the only, corrosion product. Based on these results, the voltammetric feature observed at ∼ +0.80 V vs. SCE is attributed to the reduction of RuO₄ in solution. Finally, rotating ring-disc and reflectance spectroscopy measurements provide a strong indication that the onset of O₂ evolution and Ru corrosion takes place at the same potential and thus the reaction pathways of both processes can be assumed to involve a common intermediate.