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The multimetallic nanoparticle created by Brown University chemists
for fuel-cell reactions uses a palladium core and an iron-platinum shell.
Credit: Sun Lab/Brown University

According to a Brown University press release, researchers have created a unique core-and-shell nanoparticle that uses less platinum yet performs more efficiently and lasts longer than commercially available pure-platinum catalysts at the cathode end of some fuel-cells.

A redox reaction takes place at the fuel cell’s cathode, where up to 40 percent of a fuel cell’s efficiency is lost, so, “this is a crucial step in making fuel cells a more competitive technology with internal combustion engines and batteries,” says Shouheng Sun, professor of chemistry at Brown and coauthor of the study.

The research team, which includes ACerS member and Oak Ridge National Lab researcher Karren L. More, Brown graduate student Vismadeb Mazumder and other investigators from ORNL, created a five-nanometer-wide palladium core and encircled it with a one-nanometer shell consisting of iron platinum (FePt).

The trick, Mazumder says, was in molding a shell that would retain its shape and require the smallest amount of platinum to pull off an efficient reaction. The researchers found a way to create a shell that uses only 30 percent platinum, although they expect to make thinner shells and use even less platinum.

In laboratory tests, the palladium/iron-platinum nanoparticles generated 12-times more current than commercially available pure-platinum catalysts at the same catalyst weight. The output also remained consistent over 10,000 cycles, at least 10 times longer than commercially available platinum models that begin to deteriorate after 1,000 cycles.

“This is a very good demonstration that catalysts with a core and a shell can be made readily in half-gram quantities in the lab. They’re active, and they last,” Mazumder says. “The next step is to scale them up for commercial use, and we are confident we’ll be able to do that.”

According to Sun, it is uncertain if the concept of enhanced catalysis from core/shell nanoparticles can be applied to a wide range of reactions seen in fuel cells. “Different fuel cells work in different conditions. I know our core/shell particles are good under the PEMFC conditions, but they may not survive the high operating temperature used in SOFCs.”

The findings have been published in the Journal of the American Chemical Society.

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Researchers apply the nanoparticle "inks" as a spray on the solar cells. (Credit: Beverly Barrett, UT Engineering Public Affairs)

Solar cells could soon be produced more cheaply using nanoparticle “inks” that allow them to be printed like newspaper or painted onto the sides of buildings or rooftops to absorb electricity-producing sunlight.

University of Texas, Austin chemical engineer Brian Korgel and his team have been working on this low-cost, nanomaterials solution to photovoltaics manufacturing. His team recently showed proof-of-concept in an issue of Journal of the American Chemical Society.

Korgel is hoping to cut costs to one-tenth of the current price of solar cells by replacing the standard manufacturing method of gas-phase deposition in a vacuum chamber, a process that requires high temperatures and is relatively expensive.

“That’s essentially what’s needed to make solar-cell technology and photovoltaics widely adopted,” Korgel says. “The sun provides a nearly unlimited energy resource, but existing solar energy harvesting technologies are prohibitively expensive and cannot compete with fossil fuels.”

The inks could be printed on a roll-to-roll printing process on a plastic substrate or stainless steel. And, the prospect of being able to paint the “inks” onto a rooftop or building is not far-fetched.

“You’d have to paint the light-absorbing material and a few other layers as well,” Korgel says. “This is one step in the direction towards paintable solar cells.”

Korgel uses the light-absorbing nanomaterials because their size allows for new physical properties that can help enable higher-efficiency devices. Another advantage is that the inks are semi-transparent, a property that suggests the films may find uses in window-like applications in addition to roof and panel surfaces.

Korgel and his team are using copper indium gallium selenide. “CIGS has some potential advantages over silicon,” Korgel says. “It’s a direct band gap semiconductor, which means that you need much less material to make a solar cell, and that’s one of the biggest potential advantages.”

So far, his team’s solar cell prototypes have efficiencies of only one percent, but he is optimistic. “If we get to 10 percent, then there’s real potential for commercialization,” Korgel said. “If it works, I think you could see it being used in three to five years.”

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Scientists worldwide are probably hitting their heads wondering, “Why didn’t I think of this!”

The idea for a simple new process came in a burst of inspiration: Can a camera flash instantly heat up graphite oxide and turn it into graphene?

Researchers simply hold a consumer camera flash over the graphite oxide and, a flash later, the material is now a piece of fluffy graphene. Awesome!

Previous processes to reduce graphite oxide relied on toxic chemicals or high-temperature treatment.

The process, discovered by Jiaxing Huang, assistant professor of materials science and engineering at Northwestern’s McCormick School of Engineering and Applied Science, and his graduate student Laura Cote, was published in the Aug. 12 issue of the Journal of the American Chemical Society.

Check it out:

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