Methanol oxidation on carbon supported Pt–Ru catalysts prepared by electrodeposition – Evaluation of Nafion® 117 film effect

Diverse electrochemical techniques were performed in order to obtain meaningful information about the methanol oxidation reaction on nanostructured planar carbon supported Pt–Ru electrodes prepared by electrodeposition, on which a layer of Nafion ionomer was incorporated. A metallic deposit consisting of dendritic agglomerates (between 50 and 200 nm) constituted by smaller particles (6 nm) was obtained. The average bulk Ru content obtained by EDX analysis was between 23 and 25 at. %. A decrease of the activity in the electrodes for methanol oxidation was determined when the thickness of the Nafion 117 film was increased. These results may be associated with the partial blocking of the surface active sites by hydrophobic domains of the polymer, and the presence of CO2 molecules retained within the Nafion hydrophilic microchannels. EIS results indicated that methanol electro-oxidation mechanism does not change with Nafion presence.