Materials Science

Nanoparticle Transformers

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Science  09 Aug 2013:
Vol. 341, Issue 6146, pp. 593
DOI: 10.1126/science.341.6146.593-c

On the nanometer scale, small metal nanoparticles behave neither like atoms nor a bulk material, and hence their properties can be tuned by changing the sizes of the particles, which makes them of broad research interest. When used for catalytic purposes, they are often placed onto a supporting substrate, and both it and the presence of absorbed atoms may further alter the nanoparticle properties. Li et al. studied the structure of platinum nanoparticles in the size range of 0.6 to 5 nm by using a combination of transmission electron microscopy, x-ray absorption fine-structure spectroscopy, and first-principles calculations. In studying over 3000 nanoparticles, they were able to distinguish between noncrystalline and crystalline ones. They found that there was not a single size that marked the transition between the two. Rather, the transition was a statistical one, with the potential for both ordered and disordered particles of a certain size to coexist. The coexistence size region was found to be dependent on the nature of the substrate and the amount of H2 adsorbed. The authors believe that this effect is general for late 5d transition metals.

J. Am. Chem. Soc. 10.1021/ja405497p (2013).

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