In situ Ru L_II and L_III edge x-ray absorption near edge structure of electrodeposited ruthenium dioxide films

The electronic properties of electrodeposited Ru oxide films supported on Au have been examined in situ by Ru L_III and L_II edge X-ray absorption near edge structure (XANES) in acid media. The results obtained are consistent with the main voltammetric peak centered at 0.7 V vs RHE as being attributed to a redox couple involving formally Ru³⁺ and Ru⁴⁺ sites in the lattice. A linear correlation was found between the extent of oxidation of the film as derived from a deconvolution of the spectral features and the charge as determined from coulometric analysis of the voltammetric curves. This observation suggests that only two Ru-based redox states are involved in this electrochemical process.