Morphological and electrochemical investigation of RuO2–Ta2O5 oxide films prepared by the Pechini–Adams method
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Preparation methods can profoundly affect the structural and electrochemical properties of electrocatalytic coatings. In this investigation, RuO2–Ta2O5 thin films containing between 10 and 90 at.% Ru were prepared by the Pechini–Adams method. These coatings were electrochemically and physically characterized by cyclic voltammetry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composition and morphology of the oxide were investigated before and after accelerated life tests (ALT) by EDX and SEM. SEM results indicate typical mud-flat-cracking morphology for the majority of the films. High resolution SEMs reveal that pure oxide phases exhibit nanoporosity while binary compositions display a very compact structure. EDX analyses reveal considerable amounts of Ru in the coating even after total deactivation. XRD indicated a rutile-type structure for RuO2 and orthorhombic structure for Ta2O5. XPS data demonstrate that the binding energy of Ta is affected by Ru addition in the thin films, but the binding energy of Ru is not likewise influenced by Ta. The stability of the electrodes was evaluated by ALT performed at 750 mA cm−2 in 80 °C 0.5 mol dm−3 H2SO4. The performance of electrodes prepared by the Pechini–Adams method is 100% better than that of electrodes prepared by standard thermal decomposition.
KeywordsRuthenium and tantalum oxide EDS SEM XPS Pechini–Adams method
Financial support from FAPESP, CNPq and the Center of Advanced Separation Technologies is gratefully acknowledged. J. Ribeiro also acknowledges a PhD fellowship (FAPESP -# 02/06465-0).
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