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

A systematic investigation of the structural, morphological and surface properties of thermally prepared Ru0.3Ti(0.7 - x)PtxO2 (0 less than or equal to x less than or equal to 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 TiO2 for PtOx. The electrochemical surface area increased dramatically (similar to 10 times) reaching a maximum at 40% PtOx (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-lambda,E-c,, was fixed at 0.4 V. Limiting En, 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% PtOx 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. (C) 1998 Elsevier Science Ltd. All rights reserved.4316-172515252

Titanium coated with high-performance nanocrystalline ruthenium oxide synthesized by the microwave-assisted sol-gel procedure

Ruthenium oxide coating on titanium was prepared by the sol-gel procedure from well-defined colloidal oxide dispersions synthesized by the microwave (MW)-assisted hydrothermal route under defined temperature and pressure heating conditions. The dispersions were characterized by dynamic light scattering (DLS) measurements and scanning electron microscopy (SEM). The electrochemical properties were analyzed as capacitive performances gained by cyclic voltammetry and electrochemical impedance spectroscopy and as the electrocatalytic activity for oxygen evolution from acid solution. The obtained dispersions were polydisperse and contained regular particles and agglomerates of increasing surface energy and decreasing particle size as the MW-assisted heating conditions were intensified. Owing to these features of the precursor dispersions, the obtained coatings had considerably improved capacitive performances and good electrocatalytic activity for oxygen evolution at high overpotentials