Catalytic Nanoparticles for DMFC and DFAFC: Reaction Rates, Local Densities of States, and Oxygen Shuttling Pathways

The object of this project has been to combine novel synthetic methods to produce much more active anode catalysts for fuel cells, and the use of spectroscopy to develop a molecular-level understanding of chemical physics principles of the fuel cell catalyst operation. We have made tremendous recent progress as evidenced by our 25 journal articles and 6 patents listed in Section 3.7 page 7. We have developed the most active catalysts for Direct Formic Acid Fuel Cells and discovered a correlation between spectroscopy (Pd 3d binding energy) and performance. We have observed the largest effect of particle size on fuel cell performance found to date where 3 nm palladium particles give an order of magnitude higher steady state current per exposed metal atom than 6 nm particles. We discovered a series of as yet unexplained support effects where Pd on V{sub 2}O{sub 5} gives an order of magnitude more current than pure palladium. We have verified the results in operating fuel cells and are closing in on the DOE targets of anode catalysts for portable fuel cells (costing less than $1/watt). Table 1 page 2 summarizes where these findings are described in the proposal for the reviewers reference. Generally, our approach will be to correlate spectroscopy (XPS, NMR, and STM) to kinetic (CA, CV and VI) measurements as summarized. We already have noticed a correlation between XPS binding energy and activity. We propose expanding this correlation to see if we can explain the effects of particle size and support on performance. We also propose expanding the effort using in situ STM,and EC-NMR to better characterize the changes in the catalysts as we change the support so that we can develop a fundamental understanding for catalyst design. As a second thrust of the work, we will continue of our efforts to develop novel synthetic methods to prepare electrochemical catalysts. In particular we will extend the spontaneous deposition methodology developed in previous grant cycles to the production of metal coated conducting oxide supports so we can turn the Pd on/metal oxide films that show high activity into practical catalysts