The direct methanol fuel cell (DMFC) uses methanol as fuel and has significant advantages over hydrogen-fed proton exchange membrane (PEM) fuel cells for mobile applications, particularly in terms of fuel storage and supply. Platinum (Pt) catalysts are effectively able to catalyze the oxidation of methanol to carbon dioxide in this system. However, one of the main challenges of making DMFCs commercially feasible is that the surface of Pt sites become rapidly poisoned by strongly adsorbed carbon monoxide (CO) that is produced during the oxidation process, limiting the overall rate of methanol oxidation. Studies have shown that bimetallic catalysts composed of platinum (Pt) and a second metal (i.e., Ru or Ni) are more active for the oxidation of methanol compared to catalysts composed of only Pt. Results suggest the Ru or Ni component provides sites that chemisorb H₂O in the moist environment which reacts with strongly adsorbed CO on an adjacent Pt site to form easily desorbed CO₂ [1]. In this study, we focus on the preparation of nanometer sized Pt-Ru and Pt-Ni particles supported on carbon by using the methods of strong electrostatic adsorption (SEA) and electroless deposition (ED).

The method of SEA has been used to prepare ultra-small Pt nanoparticles with high dispersions and a narrow size distribution. Catalysts prepared by SEA were then used as seed nuclei for addition of a secondary metal (Ru or Ni) using Electroless Deposition (ED). These compositions form bimetallic surfaces where Pt and Ru (or Ni) are in intimate contact to facilitate the interaction of adsorbed CO with adsorbed H₂O to form CO₂ during evaluation for methanol oxidation. These bimetallic catalysts show higher activity towards methanol oxidation than the analogous, commercial catalysts. Finally, the catalysts have been characterized by XRD, STEM, and temperature programmed methods to confirm the compositions of the bimetallic particles.

References

1. Ehteshami, S.M.M. and S.H. Chan, A review of electrocatalysts with enhanced CO tolerance and stability for polymer electrolyte membarane fuel cells. Electrochimica Acta, 2013. 93: p. 334-345.