Reports

Direct Imaging of the Atomic Configuration of Ultradispersed Catalysts

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Science  18 Oct 1996:
Vol. 274, Issue 5286, pp. 413-415
DOI: 10.1126/science.274.5286.413

Abstract

Direct imaging of individual catalyst metal atoms on the insulating surface of an industrial support is demonstrated. Individual platinum and rhodium atoms ultradispersed on γ-Al2O3 supports were imaged by high-resolution Z-contrast (atomic number Z) microscopy in a 300-kilovolt scanning transmission electron microscope. Within small clusters, the configuration of the metal atoms was seen to be constrained to match the surface structure of the γ-Al2O3, from which likely surface adsorption sites were deduced. A thin, extended raft of rhodium atoms was observed, mostly corresponding to one monolayer. Occasional two-atom features suggested partial dissolution into the top layers of the γ-Al2O3 support.