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Pt-modified RuO2 was prepared by a sol−gel procedure on titanium substrates in the form of thin films of ∼2-μm thickness. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that these films actually consist of Pt nanoparticles dispersed in RuO2 and that neither metallic Ru nor Pt−Ru alloy are present on the surface. Electrodes with different Pt:Ru nominal compositions were prepared and their electrocatalytic activity for the oxidation of methanol was investigated by potential sweeps and chronoamperometry. The results obtained show an enhancement effect for methanol oxidation that can be interpreted as associated to the formation of hydrous oxides on the RuO2 surface.

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Thin films of pure RuO2 and IrO2 and mixed Ru0.5Ir0.5O2 oxide modified with Pt particles were prepared by a sol−gel method in the form of thin films of ∼2 μm thickness on Ti substrates. Surface morphology of these Pt-modified oxides was examined by scanning electron microscopy and was found to exhibit a significant influence of the chemical composition of the oxide matrix. Element mapping showed homogeneous distribution of the metals. X-ray diffraction and X-ray photoelectron spectroscopy analyses showed that these films consist of metallic Pt particles dispersed in an oxide matrix. Cyclic voltammetry in acid solutions showed that the sol−gel prepared layers have relatively high Pt surface areas. The electrocatalytic activity of these materials toward the anodic oxidation of formaldehyde and methanol was compared in terms of onset potential and current density and was found to follow the sequence:  Pt−Ru0.5Ir0.5O2/Ti > Pt−RuO2/Ti > Pt−IrO2/Ti.

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Electrodes consisting of Pt nanoparticles dispersed on thin films of niobium oxide were prepared onto titanium substrates by a sol-gel method. The physical characterization of these electrodes was carried out by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The mean size of the Pt particles was found to be 10.7 nm. The general aspects of the electrochemical behavior were studied by cyclic voltammetry in 1 mol L -1 HClO 4 aqueous solution. The response of these electrodes in relation to the oxidation of formaldehyde and methanol in acidic media was also studied.