Sol-Gel Derived Pt-Ir Mixed Catalysts for DMFC Applications

Thin, nanoparticulate films of Pt-Ir (1.8:1 molar ratio), formed using a sol-gel derived process, show excellent activity toward methanol oxidation at room temperature for use in direct methanol fuel cells (DMFCs). When compared on a mass basis to pure Pt or Ir sol-based films, Pt 1.8 Ir yields 3.5 and 6 times higher methanol oxidation activity, respectively, and is also significantly more active than carbon-supported Johnson-Matthey PtRu (1:1). When also corrected for true surface area, the Pt 1.8 Ir catalyst continues to outperform Pt and exhibits excellent stability. The Pt-Ir catalyst is most active when dried at 250°C, and conversion of Ir to Ir oxide causes significant loss in methanol oxidation activity.