The Active Part of Real Catalysts

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Science  05 Sep 2008:
Vol. 321, Issue 5894, pp. 1268l
DOI: 10.1126/science.321.5894.1268l

Many industrial catalysts consist of metal nanoparticles on oxide supports, and in many cases this morphology increases the activity of the metal by increasing its surface area relative to the bulk metal, so that smaller particles are more active only in that more metal atoms are exposed. However, if there are electronic interactions between the oxide support (at defects or oxygen vacancies), then it is possible that a small fraction of metal particles account for most of the activity of the catalyst. Herzing et al. (p. 1331) found large differences in activity for two gold nanoparticles—iron oxide catalysts for the low temperature oxidation of CO that varied only their final preparation step (a drying procedure). High-resolution microscopy that allowed the enumeration of the various gold species, from atoms to nanoparticles, indicated that the activity varied mainly with the presence of bilayer gold nanoparticles, as has been found in studies of simpler model catalysts.

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