Methanol electrochemical oxidation at nanometer-scale PtRu materials

The electrochemical oxidation of CH3OH at nanometer-scale PtRu catalyst materials is reported. Comparisons are made between the properties of a Johnson Matthey (JM) PtRu black sample (50 at.% Ru (XRu ≈ 0.5)) and PtRu particles (2–6 nm, nominally XRu ≈ 0.5) prepared by sonication under anhydrous conditions. Cyclic voltammetry and in situ infrared spectroscopy measurements show the catalysts are active for the oxidation of 0.5 M CH3OH in 0.1 M HClO4 at temperatures between ambient and 70 °C. The sonochemically prepared PtRu sample displayed properties characteristic of bulk PtRu alloys with XRu ≈ 0.5. Evidence for phase separation of Pt and Ru was observed in CO stripping voltammetry from the JM catalyst adsorbed at low metal loadings (20 μg/cm2) on bulk Au electrodes. Per gram of catalyst, the JM material was more active toward CO2 formation and displayed greater resistance to poisoning by adsorbed CO than the sonochemically prepared material during ambient temperature oxidation of 0.5 M CH3OH in 0.1 M HClO4.