Structures and catalytic properties of PtRu electrocatalysts prepared via the reduced RuO₂ nanorods array

Structures and properties of PtRu electrocatalyts, derived from the aligned RuO₂ nanorods (RuO₂NR), are investigated using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and cyclic voltammetry toward CO_ads and methanol oxidation. The catalytic activity of methanol oxidation and the CO tolerance are promoted significantly by reducing RuO₂ into Ru metal before decorating with Pt. Reduction of RuO₂NR was carried out by either thermal decomposition at 650 °C in vacuum or H₂-reduction at 130 °C in low-pressure hydrogen. Reduction assisted by hydrogen allows infiltrating decomposition at low temperature and produces an array of nanorods with rugged walls featuring small Ru nuclei and larger surface area. Pt-RuNR, whose surface Pt:Ru ratio = 0.58:0.42 was prepared by decorating with 0.1 mg cm^-2 Pt on the H₂-reduced array containing 0.39 mg cm ^-2 Ru, demonstrates a favorable combination of CO tolerance and high methanol oxidation activity superior to other RuO₂NR-derived catalysts. When compared with a commercial electrocatalyst of PtRu (1:1) alloy (<4 nm), the activity of Pt-RuNR in methanol oxidation is shown to be somewhat lower at potential <0.48 V and higher at potential >0.48 V.