Iron Oxide Pins Gold Atoms In Place

Isolated gold atoms stay put on an iron oxide surface at temperatures of up to 400 °C, according to a study published in Physical Review Letters (DOI: 10.1103/PhysRev​Lett.108.216103). The finding may be used to prepare new model systems for surface chemistry investigations. Numerous studies have shown that oxide-supported gold particles in the low-nanometer size range catalyze oxidations and other reactions. Some researchers have proposed that these reactions are mediated by individual gold atoms, an idea that could have far-reaching industrial chemistry consequences. Testing that hypothesis has proven difficult because individual metal atoms on oxide surfaces tend to diffuse rapidly and agglomerate into nanosized chunks unless the surface is chilled to cryogenic temperatures, which are far too cold to study most chemical processes. On the basis of microscopy and spectroscopy analysis, Gareth S. Parkinson, Ulrike Diebold, and coworkers at Vienna University of Technology find that the (001) crystal face of Fe₃O₄ pins gold atoms at certain types of surface sites as a result of electronic interactions with Fe cations in the subsurface layer, and the gold atoms remain in place even as the temperature climbs to 400 °C.