Pt-Decorated Electrocatalysts for Direct Alcohol Fuel Cells
John Kitchin, Carmeline Dsilva, Diane Mattingly, and Alia Lubers. Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave, 3112 Doherty Hall, Pittsburgh, PA 15213
Reducing the amount of Pt and more effective utilization of Pt in PEM-based fuel cells is essential to making them economically attractive for power production. One approach to increasing the utilization of Pt is the use of nanoparticle electrocatalysts which maximize the available surface area for electrochemical reactions. However, we have found that small Pt nanoparticles have a lower surface activity for methanol and glycerin electro-oxidation than larger nanoparticles. This suggests that large particles are required for the most effective utilization of the surface Pt atoms, but large particles result in poor utilization of Pt on a mass basis. We have been developing two methods to decorate a cheaper metal, e.g. Ag and Au, with thin films of Pt for use in direct alcohol fuel cell applications. One approach is to electrodeposit Pt directly onto a supported Au nanoparticle electrocatalyst, while the other method uses a galvanic displacement reaction to deposit Pt onto Ag nanoparticles. These approaches allow us to retain the surface activity of the large particles with the mass activity of smaller particles. We will present the methodology for the electrodeposition and galvanic displacement synthesis and the electrochemical characterization of the electrocatalysts for the electro-oxidation of methanol and glycerin.