Ruthenium-Iridium Oxide Films Prepared by MOCVD and their Electrocatalytic Activity for Oxygen Evolution
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Ruthenium-Iridium Oxide Films Prepared by MOCVD and their Electrocatalytic Activity for Oxygen Evolution M.Z. Figueroa Torres1, M. Hesiquio Garduño2, E.M. Arce Estrada1, J.R. Vargas García1 1 Dept of Metallurgical Engineering, ESIQIE-IPN, Mexico 07300 D.F., MEXICO 2 Materials Science Dept, ESFM-IPN, Mexico 07300 D.F., MEXICO ABSTRACT Ruthenium-iridium oxide films were prepared in an horizontal hot-wall MOCVD apparatus and their electrocatalytic activity was investigated in the oxygen evolution reaction. Metalacetylacetonates were used as precursors and oxygen as the reactant gas. Appropriate deposition conditions for obtaining bi-metallic oxide films were found to be deposition temperature (Tdep), 673 K and total pressure (Ptot ), 133.32 Pa. X-Ray diffraction (XRD), Rietveld refinement and scanning electron microscopy (SEM) results demonstrated that the MOCVD method is a viable alternative to grow RuxIr1-xO2 films consisted of a single-phase with a very homogeneous distribution of elements. The electrocatalytic activity of the RuxIr1-xO2 films was investigated by cyclic voltammetry and anodic polarization curves in a 0.5 M H2SO4 solution at room temperature. The single-phase Ru0.4Ir0.6O2 films showed to be very promising for the oxygen evolution reaction due to a synergistic effect.
INTRODUCTION IrO2 and RuO2 are widely recognized as active materials for chlorine and oxygen evolution [1]. However, RuO2 undergoes corrosion during oxygen evolution in acid media whereas IrO2 is by far more stable in spite of its lower activity for this reaction [2,3]. Thus, considerable efforts have been oriented to take advantage of the extraordinary properties of the indivudual oxides by producing a mixed oxide. So far, several methods have been explored to achieve IrO2+RuO2 efficient mixed oxide electrodes for oxygen evolution, including thermal decomposition of Ru and Ir chlorides [4], reactive sputtering [5], electrodeposition [6] and sol-gel [7]. In comparison with RuO2, the IrO2+RuO2 mixed oxides exhibit an improved activity along with a higher stability in the oxygen evolution reaction [7,8]. Moreover, it has been shown that activity is strongly influenced by both the particular preparation method and the preparation conditions which in turn affect the final surface morphology, composition homogeneity and intimate mixing characteristics of the individual components. The chemical vapor deposition (CVD) method has not been explored to prepare RuO2+IrO2 oxide mixtures. In this work, the structural characterization of IrO2+RuO2 mixed oxide films prepared by metal organic chemical vapor deposition (MOCVD) is reported aiming to clarify their intrinsic crystalline nature as well as their electrocatalytic activity for the oxygen evolution in acid media.
EXPERIMENTAL RuO2, IrO2 and RuO2 + IrO2 mixed oxide films were prepared on silica glass slides (0.5×0.5×0.1 cm3) and glassy carbon (GC) rods (0.5 cm in diameter and 1.0 cm length) in a horizontal hot-wall MOCVD apparatus using metal-acetylacetonates [(CH3-COCHCO-CH3)3Ir
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