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Nanotechnology defines gold catalysts to near atomic precision

Some nanotech gold particles very effectively catalyze the oxidation of carbon monoxide to carbon dioxide—useful for protecting firefighters and fuel cells from carbon monoxide poisoning. A very powerful electron microscope capable of resolving single gold atoms has revealed why some gold nanoparticles work and some don’t—only bilayer clusters of 8-12 gold atoms work. Via PhysOrg.com, from Lehigh University “Scientists peel away the mystery behind gold’s catalytic prowess“:

Lehigh University’s scanning transmission microscopes helped expose gold’s nanostructure to reveal its lesser known properties.

…gold nanoparticles effectively catalyze the critical conversion of toxic carbon monoxide (CO) into more benign carbon dioxide (CO2) at room temperature. CO oxidation is vital to firefighters and others who must enter burning buildings. It is also critical to the protection of hydrogen fuel cells from CO contamination.

…Now, researchers from Lehigh and from Cardiff University in Wales and the U.S. National Institute of Standards and Technology (NIST) believe they have pinpointed the active species at which the oxidation reaction occurs when gold is supported on iron oxide.

In an article published last week in Science [abstract], the team reports that bilayer clusters measuring about one-half nanometer in diameter and containing about 10 gold atoms are responsible for triggering the CO oxidation reaction.

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 in static air — helps impart to the gold its catalytic capability.

…The aberration-corrected STEM enabled Herzing and Kiely to use a microscopy technique called high-angle annular dark-field imaging, which requires an extremely fine, 1-angstrom-wide beam of electrons to obtain a scanned image of a specimen. An angstrom is equal to one-tenth of a nanometer.

…Gold catalysts are also being explored for their effectiveness in catalyzing the reaction that is used to steam-reform methane into hydrogen.

—Jim

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