Smaller is better when it comes to catalysts

By Deborah Rafferty, Staff Writer

Size really does matter8212;at least for catalysts.

U scientists found that the size of catalysts, substances that speed up chemical reactions, directly affect their electronic properties. Thanks to the discovery, scientists could be able to decrease the cost to use catalysts, which are used in energy production.

Scott Anderson, a U professor of chemistry, headed this research, which was funded by the U.S. Air Force. The goal was to better understand how catalysts work to decrease the cost of developing catalysts and make them more efficient.

“Catalysts are not well understood,” said Bill Kaden, a graduate student in chemistry, who also worked on the study. “We know that they work, but the way in which they work is a mystery.”

Catalysts are used to produce, store and clean power sources, he said. The use of a catalyst is involved in almost anything that has a need for power. The most commonly known catalyst is the catalytic converter in cars, which uses metals such as palladium, platinum and rhodium. Catalysts are also used in the production of gasoline. With this new research, these processes can decrease in cost, making the production of power cheaper, Kaden said.

The key difference in this research compared to the research of other studies involving catalysts was its focus on their size. The researchers found that when the size of a catalyst decreases, the electrical properties change. In catalysts, such as the metal palladium, only certain parts of the metal are used. By decreasing the size, researchers can use only the parts of the catalyst that are active during the chemical reaction, lowering the cost of producing them, Kaden said.

“If you take a bulk piece of metal and make it smaller and smaller, at some level you find more electrons which start to change the behavior,” Kaden said. “A smaller catalyst can be more efficient.”

The researchers studied palladium, which is a commonly used catalyst. They vaporized a piece of the palladium with a laser, creating electrically charged particles. Then the researchers used helium to condense the palladium particles, creating new samples of varying sizes, Kaden said. Using an electromagnetic field, the scientists filtered out the particles they did not wish to study. They then characterized the particle’s electronic properties, chemical activity and shape, he said.

“You could design high-efficiency and low-cost catalysts,” Kaden said. “You could save money making catalysts and by increasing their efficiency.”

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