The kinetics and mechanism of methanol oxidation on Pt and PtRu catalysts in alkaline and acid media

The kinetic of methanol electrochemical oxidation for a series of platinum and platinum-ruthenium catalysts was investigated. A correlation between the beginning of OHad adsorption and methanol oxidation was demonstarated on Pt single crystals and Pt nanocatalyst. The activity of the nano-structured Pt catalyst was compared with single crystal platinum electrodes assuming the Kinoshita model of nanoparticles. The ruthenium-containing catalysts shifted the onset of methanol oxidation to more negative potentials. The effect was more pronounced in acid than in alkaline media. Based on the established diagnostic criteria, the reaction between COad and OHad species according to the Langmuir-Hinshelwood mechanism was proposed as the rate determining step in alkaline and acid media on Pt and PtRu catalysts.