Researchers shed new light on catalyzed...(is found at 60 percent of the contaminat...)

Wong's research group developed a new palladium-gold catalyst several years ago that helps break TCE into nontoxic components -- unlike methods that just move TCE into the solid phase or gas phase. Early tests showed that the new catalyst worked remarkably quickly. In fact, it was more efficient than predicted, based on the best available theories. "The gold was definitely playing a role that we didn't fully understand," Wong said.

To learn more, Wong approached Halas and Rice theoretical chemist Gustavo Scuseria. Halas had worked for years to develop spectroscopic methods that used gold nanoshells for chemical detection and analysis. Whereas Wong's four-nanometer particles have a gold center covered by palladium atoms, he and graduate student Kimberly Heck wondered if they could cover Halas' much larger gold nanoshells with palladium atoms and then use the nanoshells to detect the elusive TCE chemical reaction. "We also didn't know how the TCE molecules decomposed on the catalyst surface," Wong said.

It took about a year and half to develop the technology and work out the experimental kinks, but Wong said the results were worth waiting for. The method uses surface-enhanced Raman spectroscopy to reveal the structure and makeup of molecules sitting on the palladium-covered gold nanoshell surface. Scuseria, Rice's Welch Professor of Chemistry, and postdoc Ben Janesko provided sophisticated theoretical calculations that helped match the vibrations with the type of chemical bonds.

"We think we parsed it out pretty well," Wong said of the hydrodechlorination reaction. "Millions of surface-bound molecules are reacting simultaneously, but with a lot of work we've uncovered at least seven ch
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