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  • Shrisudersan Jayaraman (a1) and Andrew C. Hillier (a1)

Combinatorial methods represent an appealing experimental method for the discovery of heterogeneous catalysts. One can efficiently identify candidate materials or sample vast regions of composition space using a combination of dense catalyst libraries and high-throughput reactivity screening techniques. This is particularly appealing for the discovery of novel catalysts for low temperature fuel cells where multi-component systems have shown improved performance. For example, the poison tolerance of typical anode catalysts can be improved by the addition of oxophilic components such as ruthenium, molybdenum, tin or osmium. Consequently, a vast composition space must be sampled in order to identify catalyst compositions or regions of composition space with greater activity. Combinatorial methods represent a practical means to speed-up the catalyst discovery process. In this manuscript, we demonstrate a novel method for combinatorial catalyst discovery based upon the synthesis and reactivity mapping of catalyst composition gradients. Samples consisting of uniform variations in surface composition of metals catalysts (Pt-M1 and Pt-M1−M2, where M1, M2 = Ru, Mo, Sn or Os) are fabricated using a gel-transfer technique. A concentration gradient of source metal ions is produced in a swollen polymer gel and then transferred onto a surface by electrodeposition to create a continuous composition gradient. An in situ reactivity-mapping tool based on the scanning electrochemical microscope is used to interrogate these catalyst gradients for the hydrogen oxidation reaction in the presence of adsorbed carbon monoxide.

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1. Rawlings, R. Tailoring properties - functionally graded materials. Materials World 3, 474475 (1995).
2. Marple, B. R. & Boulanger, J., Graded casting of materials with continuous gradients. J. Amer. Cer. Soc. 77, 27472750 (1994).
3. Neubrand, A. & Rodel, J. Gradient materials: An overview of a novel concept. Z. Metal. 88, 358371 (1997).
4. Ruardy, T. G., Schakenraad, J. M., vanderMei, H. C. & Busscher, H. J. Preparation and characterization of chemical gradient surfaces and their application for the study of cellular interaction phenomena. Surf. Sci. Rep. 29, 330 (1997).
5. Xiang, X.-D. et al. A combinatorial approach to materials discovery. Science 268, 17381740 (1995).
6. Reddington, E. et al. Combinatorial electrochemistry: a highly parallel, optical screening method for discovery of better electrocatalysts. Science 280, 17351737 (1998).
7. Ertl, G., Neumann, M. & Streit, K. M. Chemisorption of CO on the Pt(111) surface. Surf. Sci. 64, 393410 (1977).
8. Appleby, A. J. & Foulkes, F. R. Fuel Cell Handbook (Van Nostrand Reinhold, New York, 1989).
9. Gasteiger, H. A., Markovic, N. M. & Ross, P. N. H2 and CO electrooxidation on well-characterized Pt, Ru, and Pt-Ru.1. Rotating-disk electrode studies of the pure gases including temperature effects. J. Phys. Chem. 99, 82908301 (1995).
10. Houghten, R. A. et al. Generation and use of synthetic peptide combinatorial libraries for basic research and drug discovery. Nature 354, 8486 (1991).
11. Danielson, E. et al. A rare-earth phosphor containing one-dimensional chains identified through combinatorial methods. Science 279, 837839 (1998).
12. Huo, Q., Sui, G., Kele, P. & Leblanc, R. M. Combinatorial surface chemistry- Is it possible? Angew. Chem. - Int. Ed. 39, 18541857 (2000).
13. Taylor, S. J. & Morken, J. P. Thermographic selection of effective catalysts from an encoded polymer-bound library. Science 280, 267270 (1998).
14. Cong, P. J. et al. High-throughput synthesis and screening of combinatorial heterogeneous catalyst libraries. Angew. Chem. - Int. Ed. 38, 484488 (1999).
15. Chaudhury, M. K. & Whitesides, G. M. How to make water run uphill. Science 256, 15391541 (1992).
16. Elwing, H. & Gölander, C. G. Protein and detergent interaction phenomena on solid-surfaces with gradients in chemical-composition. Adv. Coll. and Int. Sci. 32, 317339 (1990).
17. Dertinger, S. K. W., Chiu, D. T., Jeon, N. L. & Whitesides, G. M. Generation of gradients having complex shapes using microfluidic networks. Anal. Chem. 73, 12401246 (2001).
18. Fuierer, R. R., Carroll, R. L., Feldheim, D. L. & Gorman, C. B. Patterning mesoscale gradient structures with self-assembled monolayers and scanning tunneling microscopy based replacement lithography. Adv. Mater. 14, 154-+ (2002).
19. Tingey, M. L., Luk, Y. Y. & Abbott, N. L. Orientations of liquid crystals on chemically functionalized surfaces that possess gradients in manometer-scale topography. Adv. Mater. 14, 1224-+ (2002).
20. Balss, K. M., Coleman, B. D., Lansford, C. H., Haasch, R. T. & Bohn, P. W. Active spatiotemporal control of electrochemical reactions by coupling to in-plane potential gradients. J. Phys. Chem. B 105, 89708978 (2001).
21. Jayaraman, S. & Hillier, A. C. Construction and reactivity mapping of a platinum catalyst gradient using the scanning electrochemical microscope. Langmuir 17, 78577864 (2001).
22. Lee, K. Y. C., Klingler, J. F. & McConnell, H. M. Electric-field-induced concentration gradients in lipid monolayers. Science 263, 655658 (1994).
23. Groves, J. T., Boxer, S. G. & McConnell, H. M. Electric field-induced critical demixing in lipid bilayer membranes. Proc. Nat. Acad. Sci. 95, 935938 (1998).
24. Meredith, J. C., Smith, A. P., Karim, A. & Amis, E. J. Combinatorial materials science for polymer thin-film dewetting. Macromolecules 33, 97479756 (2000).
25. Meredith, J. C., Karim, A. & Amis, E. J. High-throughput measurement of polymer blend phase behavior. Macromolecules 33, 57605762 (2000).
26. Wu, T., Efimenko, K. & Genzer, J. Combinatorial study of the mushroom-to-brush crossover in surface anchored polyacrylamide. J. Amer. Chem. Soc. 124, 93949395 (2002).
27. Bard, A. J. & Mirkin, M. V. Scanning Electrochemical Microscopy (Marcel Dekker, Inc., 2001).
28. Jambunathan, K., Shah, B. C., Hudson, J. L. & Hillier, A. C. Scanning electrochemical microscopy of hydrogen electro- oxidation. Rate constant measurements and carbon monoxide poisoning on platinum. J. Electroanal. Chem. 500, 279289 (2001).
29. Lee, C., Miller, C. J. & Bard, A. J. Scanning electrochemical microscopy: Preparation of submicrometer electrodes. Anal. Chem. 63, 7883 (1991).
30. Shah, B. C. & Hillier, A. C. Imaging the reactivity of electro-oxidation catalysts with the scanning electrochemical microscope. J. Electrochem. Soc. 147, 30433048 (2000).
31. Cussler, E. L. Diffusion: Mass Transfer in Fluid Systems (Cambridge University Press, 1997).
32. Watanabe, M. & Motoo, S. Electrocatalysis by ad-atoms part III. Enhancement of the oxidation of carbon monoxide on platinum by ruthenium ad-atoms. Electroanal. Chem. and Interfac. Electrochem. 60, 275283 (1975).
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