Bruce van Dover1,
John Gregoire12, Darren Dale3,
and Alexander Kazimirov3
1Materials Science and Engineering, Cornell University
2Department of Physics, Cornell University
3CHESS Synchrotron X-Ray Source, Cornell University
Abstract:
We use a combinatorial approach to identify new catalyst materials for low temperature (polymer electrolyte membrane) fuel cells. Our approach allows us to evaluate catalytic activity in most of the ternary phase diagram of any given trimetallic combination in a single experiment. We prepare ternary thin film composition spreads on 75-mm Si wafer substrates using magnetron cosputtering of elemental targets. We evaluate the entire spread quickly using a simple electrochemical test that employs a fluorescent pH indicator to identify regions of high catalytic activity (low onset potential and high turnover). We have developed an x-ray diffraction configuration using the CHESS A2 (60 keV) line that permits high-throughput mapping of x-ray diffraction in a transmission geometry and simultaneous x-ray fluorescence spectroscopy measurements. Techniques for the analysis of powder XRD patterns from inorganic libraries using principal-component analysis, metric multidimensional scaling, and clustering techniques have been reported in the literature, but several properties of inorganic phases pose significant problems for these algorithms. We are developing new algorithms for automated phase mapping of continuous composition spread thin films. This will ultimately allow us to correlate crystal structure, composition, and microstructure (film texture) with catalytic activity. Using this approach, promising new materials have been identified. This work is supported by the Cornell Fuel Cell Institute.
2009 Run
Sept. 23rd to Nov. 10th
