Brookhaven Lab physicists Peter Sutter, Eli Sutter,and Xiao Tong (left to right) with one of the Center for Functional Nanomaterials instruments used to characterize the new nanoparticle structures. | Photo courtesy of Brookhaven National Lab.
“A little fresh air will be good for you.” So parents say, especially when they’re trying to kick a slightly comatose teenager off the couch during summer vacation.
Turns out that a little air can be good for increasing the activity of molecules too, according to researchers at the Energy Department’s Brookhaven National Lab.
The scientists at Brookhaven’s Center for Functional Nanomaterials were trying to increase the activity of gold. Gold is typically quite unreactive. However, with the right incentives, it is capable of astonishing productivity, especially speeding chemical reactions while not being consumed (a process called catalysis).
Gold can be an outstanding catalyst when separated into tiny, discrete nanoparticles. But under even moderate heat -- a point that will be important below -- gold particles tend to glom together and then shut down. Mixing gold with other metals can help, but sustaining their intense catalytic activity requires a nearly perfect setup.
So the Brookhaven scientists tried a simple approach: They insisted the gold get some fresh air. Namely, they created nanoparticles of gold and the metal indium, and then exposed them to oxygen. In theory, it wouldn’t work. The oxygen and indium would connect, pushing the gold particles together in an unreactive center and driving few chemical reactions. But in practice, adding oxygen caused shells of a gold-indium oxide to form across the surface of the nanoparticles.
Not only was the new compound highly catalytic, it also kept its structural integrity at high temperatures, such as those found in car engines. That’s where the compound has particularly high potential, since it is particularly good at taking carbon monoxide (the colorless, odorless stuff that’s especially bad to inhale) and combining it with oxygen to produce carbon dioxide, which is more benign.
Car engines produce traces of carbon monoxide -- it’s simply an imperfect part of the burning process -- but they use catalytic converters to reduce that pollutant, and others, such as nitrogen oxides. Catalytic converters often use a platinum catalyst to cleanse carbon monoxide from the exhaust, but the gold-indium compound created at Brookhaven Lab could prove cheaper and perhaps more durable.
Researchers may find more uses for that compound, and perhaps related compounds with new and novel uses too. That will be part of their continuing efforts using the unique capabilities of the Center for Functional Nanomaterials.
Sometimes, fresh air can be as good as gold.