Methanol oxidation reaction on Ti/RuO 2( x) Pt (1− x) electrodes prepared by the polymeric precursor method

Abstract

In this work, ruthenium oxide films containing platinum nanoparticles were prepared using the polymeric precursor method on Ti substrates with several molar ratios. This paper aims at presenting the characterization of the Pt content effect in the methanol electrochemical oxidation reaction. The films were physically characterized using X-ray diffraction and both Pt and RuO 2 (rutile) phases were observed. The mean crystallite sizes were 6 nm for Pt and 25 nm for RuO 2. The X-ray photoelectronic results indicated that on the electrodes surfaces, depending on the substrate, there was RuO 2, Ru metal and Pt metal. Besides, it was not observed the formation of PtRu alloys. The atomic force microscopy images of the films showed highly rough surfaces. A decrease in the roughness mean square values is observed as the Pt content increases. These last results are similar to electroactive surface area values calculated by redox-couple (K 4FeCN 6/K 3FeCN 6). There was an increase in the globular size observed on the electrode surface and lower particle dispersion as the Pt content is increased from 12.5 to 75 mol%. Regarding the eletrode electrocatalytical behavior for methanol oxidation, it was observed that the onset oxidation overpotential is displaced towards more negative values as Pt content is decreased. Besides, an increase has been shown in the current density for methanol oxidation of 600% using a Ti/RuO 2-Pt (87.5:12.5) electrode compared to polycrystalline Pt.