Methanol oxidation on carbon-supported Pt-Ru-Ni ternary nanoparticle electrocatalysts

Methanol oxidation on carbon-supported Pt-Ru-Ni ternary alloy nanoparticles was investigated based on the porous thin-film electrode technique and compared with that on Johnson-Matthey Pt-Ru alloy catalyst. Emphasis is placed on the effect of alloying degree on the electrocatalytic activity and stability of the ternary catalysts. The as-prepared Pt-Ru-Ni nanoparticles exhibited a single phase fcc disordered structure, and a typical TEM image indicates that the mean diameter is ca. 2.2 nm, with a narrow particle size distribution. Also, the as prepared Pt-Ru-Ni catalysts exhibited significantly enhanced electrocatalytic activity and good stability for methanol oxidation in comparison to commercial Pt-Ru catalyst available from Johnson-Matthey. The highest activity of methanol oxidation on Pt-Ru-Ni catalysts was found with a Pt-Ru-Ni atomic ratio of 60:30:10 and at a heat-treatment temperature of ca. 175 °C. The significantly enhanced catalytic activity for methanol oxidation is attributed to the high dispersion of the ternary catalyst, to the role of Ni as a promotion agent, and especially to the presence of hydroxyl Ru oxide. Moreover, the stability of the ternary nanocatalytic system was found to be greatly improved at heat-treatment temperatures higher than ca. 250 °C, likely due to a higher alloying degree at such temperatures for the ternary catalysts.