Structural, morphological and surface properties as a function of composition of Ru+Ti+Pt mixed-oxide electrodes

• Published in: Electrochimica acta 1998-01, Vol.43 (16), p.2515-2525
• Main Authors: Lassali, T.A.F., De Castro, S.C., Boodts, J.F.C.
• Format: Article
• Language: English
• Subjects: Chemistry; Electrochemistry; Electrodes: preparations and properties; Exact sciences and technology; General and physical chemistry; mixed-oxide electrodes, surface characterization, electrocatalysts, ruthenium dioxide, platinum oxide; Other electrodes
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/S0013-4686(97)00306-X

A systematic investigation of the structural, morphological and surface properties of thermally prepared Ru 0.3Ti (0.7− x) Pt x O 2 (0⩽ x⩽0.7) electrodes was conducted by ex situ (SEM, EDX, XPS) and in situ (voltammetry and open circuit potential) techniques. Significant changes were observed on substituting TiO 2 for PtO x . The electrochemical surface area increased dramatically (∽10 times) reaching a maximum at 40% PtO x (nominal). Ru surface enrichment was observed while Pt+Ru segregates as rectangular crystals from the coatings. At the higher Pt-contents, surface electrochemistry is mainly dominated by Pt solid-state transitions, especially after continuous potential cycling (0.4–1.4 V vs r.h.e.). Pt-containing coatings were revealed to be unstable (erosion) when the cathodic switching potential, E λ,c , was fixed at 0.4 V. Limiting E λ,c to 0.9 V vs r.h.e. eliminates coating instability. Preferential Ru dissolution, promoted by cathodic Pt dissolution, was revealed by ICPES. With the exception of the 0–20% PtO x containing coatings, where evidence for the presence of Ru VI was found, Ti and Ru are present in the +4 oxidation while the +2 oxidation state predominates for Pt.