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Researchers develop unique method for creating uniform nanoparticles

Posted on May 7, 2013
This is a micrograph showing array of atoms and tetrahedral subunits in a single icosahedral Pt particle. Credit: Hong Yang, University of Illinois

This is a micrograph showing array of atoms and tetrahedral subunits in a single icosahedral Pt particle. Credit: Hong Yang, University of Illinois

University of Illinois researchers have developed unique approach for the synthesis of highly uniform icosahedral nanoparticles made of platinum. Results showed that the key factors for the shape control include fast nucleation, kinetically controlled growth, and protection from oxidation by air.

“We have developed unique approach for the synthesis of highly uniform icosahedral nanoparticles made of platinum (Pt),” explained Hong Yang, a professor of chemical and biomolecular engineering at the University of Illinois at Urbana-Champaign. “This is important both in fundamental studies—nanoscience and nanotechnology—and in applied sciences such as high performance fuel cell catalysts.”

34-33-32-31-30-29-28-27-26-25-24-23-22-21-20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-3-2-1-researchersd[1]Yang’s research group focuses on the synthesis and understanding structure-property relationship of nanostructured materials for applications in energy, catalysis, and biotechnology. Its paper, “Highly Uniform Platinum Icosahedra Made by the Hot Injection-Assisted GRAILS Method,” was published this week in Nano Letters.

This is a micrograph showing the uniformity of the nanocrystals at low magnification. Credit: Hong Yang, University of Illinois

This is a micrograph showing the uniformity of the nanocrystals at low magnification. Credit: Hong Yang, University of Illinois

“Although polyhedral nanostructures, such as a cube, tetrahedron, octahedron, cuboctahedron, and even icosahedron, have been synthesized for several noble metals, uniform Pt icosahedra do not form readily and are rarely made,” stated Wei Zhou, a visiting scholar with Yang’s research group and the paper’s first author.

An icosahedron crystal is a polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. According to Yang, icosahedral shaped crystals can improve the catalytic activity in oxygen reduction reaction partly because of the surface strain.
“The key reaction step to improve the activity of oxygen electrode catalysts in the hydrogen fuel cell is to optimize the bond strength between Pt and absorbed oxygen-containing intermediate species,” Yang said. “This allows the rapid production of water and let the intermediate react and leave the surface quickly so the catalyst site can be used again.”

Read more at: Phys.org

   
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