J. Grunes, J. Zhu, E. A. Anderson and G. A. Somorjai  "Ethylene Hydrogenation over Platinum Nanoparticle Array Model Catalysts Fabricated by Electron Beam Lithography: Determination of Active Metal Surface Area" J. Phys. Chem.B 106, 11463 (2002).

Jeff Grunes, Ji Zhu, Minchul Yang, and Gabor A. Somorjai "CO Poisoning of Ethylene Hydrogenation over Pt Catalysts: A Comparison of Pt(111) Single Crystal and Pt Nanoparticles Activities," Cat. Lett. 86, 157 (2003).

Description:

Designing catalytic systems to be fast acting and long-lived, and to form only the desired end products, has long been a major challenge.  Nanotechnology is quickly addressing that challenge.  Researchers are discovering the importance that size and distribution of the catalyst particles has.  Techniques of nanofabrication allow catalysts to be created with more precision and smaller feature sizes than ever before.  Oxidized silicon crystal is coated with a thin film of polymer, then an electron beam is used to burn a pattern of holes through the polymer to the substrate.  A platinum film is then evaporated onto the polymer, and it fills in the holes; when the polymer is removed, only platinum clusters of uniform size and spacing are left.

The result is a wafer of silicon oxide half a square centimeter in area, covered with a billion particles of platinum spaced 100 nanometers apart.  When viewed with an atomic force microscope the platinum particles were found to be some 20 nanometers in diameter and about 15 nanometers high.
 

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