From JHU HUB: “With new technique, researchers create metallic alloy nanoparticles with unprecedented chemical capabilities”

Johns Hopkins

Rachel Wallach

New, stable nanoparticles are expected to have useful applications in the chemical and energy industries. Image credit: Getty Images

Johns Hopkins researchers have teamed with colleagues from three other universities to combine up to eight different metals into single, uniformly mixed nanoparticles, creating new and stable nanoparticles with useful applications in the chemical and energy industries, the researchers said.

Metallic alloy nanoparticles—particles ranging from about a billionth to 100 billionths of a meter in size—are often used as catalysts in the production of industrial products such as fertilizers and plastics. Until now, only a small set of alloy nanoparticles have been available because of complications that arise when combining extremely different metals.

In the March 30 cover article of the journal Science, the researchers reported that their new technique made it possible to combine multiple metals, including those not usually considered capable of mixing.

“This method enables new combinations of metals that do not exist in nature and do not otherwise go together,” said Chao Wang, an assistant professor in the Department of Chemical and Biomolecular Engineering at Johns Hopkins and one of the study’s co-authors.

The new materials, known as high-entropy-alloy nanoparticles, have created unprecedented catalytic mechanisms and reaction pathways and are expected to improve energy efficiency in the manufacturing process and lower production costs.

The new method uses shock waves to heat the metals to extremely high temperatures—2,000 degrees Kelvin (more than 3,140 Fahrenheit) and higher—at exceptionally rapid rates, both heating and cooling them in the span of milliseconds. The metals are melted together to form small droplets of liquid solutions at the high temperatures and are then rapidly cooled to form homogeneous nanoparticles. Traditional methods, which rely on relatively slow and low-temperature heating and cooling techniques, often result in clumps of metal instead of separate particles.

Based on these new nanoparticles, Wang’s research group designed a five-metal nanoparticle that demonstrated superior catalytic performance for selective oxidation of ammonia to nitrogen oxide, a reaction used by the chemical industry to produce nitric acid, which is used in the large-scale production of fertilizers and other products.

In addition to nitric acid production, the researchers are exploring use of the nanoparticles in reactions like the removal of nitrogen oxide from vehicle exhaust. The work in Wang’s lab was part of a collaboration with colleagues from the University of Maryland, College Park; the University of Illinois at Chicago; and MIT.

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About the Hub

We’ve been doing some thinking — quite a bit, actually — about all the things that go on at Johns Hopkins. Discovering the glue that holds the universe together, for example. Or unraveling the mysteries of Alzheimer’s disease. Or studying butterflies in flight to fine-tune the construction of aerial surveillance robots. Heady stuff, and a lot of it.

In fact, Johns Hopkins does so much, in so many places, that it’s hard to wrap your brain around it all. It’s too big, too disparate, too far-flung.

We created the Hub to be the news center for all this diverse, decentralized activity, a place where you can see what’s new, what’s important, what Johns Hopkins is up to that’s worth sharing. It’s where smart people (like you) can learn about all the smart stuff going on here.

At the Hub, you might read about cutting-edge cancer research or deep-trench diving vehicles or bionic arms. About the psychology of hoarders or the delicate work of restoring ancient manuscripts or the mad motor-skills brilliance of a guy who can solve a Rubik’s Cube in under eight seconds.

There’s no telling what you’ll find here because there’s no way of knowing what Johns Hopkins will do next. But when it happens, this is where you’ll find it.

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The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.