Among the major obstacles to the successful application of Pt-Ru alloys as anode electrocatalysts for direct methanol fuel cells are their low electrocatalytic activities and poor stability under demanding operating conditions. In particular, detrimental is the eventual dissolution of the more oxophilic Ru. In this work, a novel carbon-supported gold-stabilized Pt-Au@Ru catalyst was synthesized using the water-in-oil microemulsion method. The catalyst possesses an enhanced methanol oxidation activity in acid medium and significantly enhanced stability over a commercially available Pt-Ru/C catalyst (E-TEK, 60%). This work provides a representative example of stabilization of an oxophilic transition element, Ru, using a unique ternary structure with Au. The stabilized surface and bulk composition are determined through copper under-potential deposition, transmission electron microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy in conjunction with electrochemical measurements. In situ X-ray absorption spectroscopy analysis revealed that the addition of gold in the Pt-Au@Ru/C catalyst enhances the stability of the catalyst chiefly by interacting electronically with the Pt and Ru to raise their oxidation potentials.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films