Chemistry

Edgy Catalysts

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Science  07 Feb 2003:
Vol. 299, Issue 5608, pp. 783
DOI: 10.1126/science.299.5608.783c

There is renewed interest in gold as a financial investment. It also has attracted attention as a catalyst; the bulk metal is unreactive, but small particles (∼5 nm) are highly active in oxidizing CO at room temperature.

Mohr et al. have prepared gold catalysts on zinc oxide (ZnO) supports and show that they promote the selective hydrogenation of the C=O bond (instead of the more reactive C=C bond) of unsaturated aldehydes. The activity and selectivity of these catalysts depend not only on particle size but on particle shape, too—for example, particles may be rounded or twinned. Many of the gold particles are single crystals with sharp facets and a narrow size distribution. When the authors added a second metal, indium, it preferentially coated the outer faces of the particles, leaving the edges free. By varying the amount of indium, the authors showed that hydrogenation of the C=O group of acrolein occurred at the edges of the particles rather than on the surfaces. Such detailed insights into nanoparticle catalysis may help to tune performance and enhance selectivity. — JFU

J. Am. Chem. Soc. 10.1021/ja027321q (2003).

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