Few materials have exercised as much of a hold on the human imagination, or on human history, as has gold.
But for all of its popular uses money, medals, jewelry and more gold's potential as a catalyst lay hidden until the 1980s, when Masatake Haruta and Graham Hutchings independently discovered that gold, which had long been considered inactive, could be an extraordinarily good catalyst. Haruta demonstrated the low-temperature oxidation of CO and Hutchings the hydrochlorination of acetylene to vinyl chloride.
Gold particles measuring less than 5 nanometers in diameter possess a high level of catalytic activity when they are deposited on metal-oxide supports, Haruta learned. One nanometer (nm) is equal to one one-billionth of a meter, or about the width of five atoms.
In particular, Haruta found that gold nanoparticles are effective at catalyzing the critical conversion of toxic carbon monoxide (CO) into more benign carbon dioxide (CO2) at room temperature and even at temperatures as low as -76 degrees C. CO oxidation is vital to firefighters and others who must enter burning buildings, and it is also critical to the protection of hydrogen fuel cells from CO contamination.
In the two decades since Haruta's discovery, scientists have sought to determine exactly how gold nanoparticles function as catalysts.
Now, researchers from Lehigh University in Bethlehem, Pa., and Cardiff University in the UK believe they have pinpointed the active species at which the critical oxidation reaction occurs when gold is supported on iron oxide.
In an article to be published in Science, the premier scientific journal in the U.S., researchers from Lehigh University in Bethlehem, Pa.; Cardiff University in Wales, and the National Institute of Standards and Technology (NIST) report that bilayer clusters measuring about one-half nanometer in diameter and containing only about 10 gold atoms are responsible for triggeri
|Contact: Kurt Pfitzer|