Electrochemistry of ruthenates. Part 1.—Oxygen reduction on pyrochlore ruthenates

The reduction of dioxygen to water has been investigated on ternary ruthenium(IV) oxides having the pyrochlore structure; in particular, compounds of the general form Bi2–2xPb2xRu2O7-y have been studied. Oxygen reduction on these materials appears to proceed by a rate-determining outer-sphere electron transfer, followed by displacement of OH– groups coordinated to RuIV by the much stronger nucleophile O2H˙. The cyclic voltammetry of these oxides is interpreted in the light of the X-ray and ultraviolet photoelectron spectra, and a connection between the bandwidth in these oxides and the potential of the main redox processes observed on the voltammagrams is suggested.