The researchers, using aberration-corrected transmission electron microscopy capable of resolving single gold atoms, also report that a simple change in preparation the drying of the catalyst in flowing rather than static air helps impart to the gold its catalytic capability.
The article, titled "Identification of Active Gold Nanoclusters on Iron Oxide Supports for CO Oxidation," is scheduled to be published in the Sept. 5 issue of Science.
Its authors are Christopher Kiely, director of the Nanocharacterization Laboratory in Lehigh's Center for Advanced Materials and Nanotechnology; Graham Hutchings, Albert Carley and Philip Landon of Cardiff's School of Chemistry; and Andrew Herzing of NIST's Surface and Microanalysis Science Division. Herzing earned a Ph.D. from Lehigh in 2006.
Hutchings and Kiely have collaborated since 1989 and have worked together on gold catalysts since 2000. In this project, Hutchings' group carried out the fabrication and catalytic testing of the gold nanoparticles, and the characterization of the catalyst using x-ray photoelectron spectroscopy (XPS). Kiely's group then used Lehigh's aberration-corrected 2200 JEOL scanning transmission electron microscope (STEM) to examine the gold's nanostructure. Lehigh is currently the only university in the world with two aberration-corrected electron microscopes, which are the world's most powerful instruments for chemical analysis.
The researchers compared two groups of gold nanoparticles. One, dried in static air, was what scientists call a "dead" catalyst with little or no catalytic activity. The other group, dried with flowing air, was a 100-percent-active catalyst for CO oxidation.
On the inactive catalyst, Herzing saw two types of gold species particles larger than 1 nm in size and individual atoms scattered about on the iron-oxide support. On the 100-percent-active catalyst, he found a third species cl
|Contact: Kurt Pfitzer|