Event
MSE Seminar: Prof. Bryan Eichhorn, Dept. of Chemistry and Biochemistry, UMD
Friday, February 6, 2009
1:00 p.m.
Rm. 2108, Chemical and Nuclear Engineering
Annette Mateus
301 405 5207
amateus@umd.edu
Architectural Effects in Bimetallic Nanostructures: Pt-Ru Bimetallic Catalysts for Fuel Cells and Preferential CO Oxidation Applications
We show how controlling the architecture in bimetallic nanocatalysts dramatically changes the catalytic activity in heterogeneous transformations. Pt-Ru nanoparticles of the same size and composition can be prepared in four different architectures: alloys, core-shell particles, mixtures of monometallic particles, and linked monometallic particles. Full structural and compositional characterization of the particles and catalysts requires multiple analytical techniques, including TEM-EDS, XRD, PDF, EXAFS, XANES and surface probe studies. These systems have been investigated for use in preferential oxidation of CO contaminates in hydrogen feeds (PROX) and for CO-tolerant hydrogen PEMFC anode electrocatalysts. We show that core-shell structures dramatically alter the catalytic properties and are far superior to traditional PtRu bimetallics for PROX applications. In addition, they show unusual activities for hydrogen electro-oxidation in CO contaminated environments. In rotating disk electrochemical experiments (RDE), the core-shell particles act as thermal PROX catalysts and hydrogen electrocatalyts, which may have important implications for the direct use of reformate hydrogen in PEMFCs. Mechanistic studies and correlations between core shell particles and Near Surface Alloy (NSA) theory will be presented.