Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > In 'novel playground,' metals are formed into porous nanostructures

Abstract:
For 5,000 years or so, the only way to shape metal has been to "heat and beat." Even in modern nanotechnology, working with metals involves carving with electron beams or etching with acid. Now, Cornell researchers have developed a method to self-assemble metals into complex nanostructures. Applications include making more efficient and cheaper catalysts for fuel cells and industrial processes and creating microstructured surfaces to make new types of conductors that would carry more information across microchips than conventional wires do.

In 'novel playground,' metals are formed into porous nanostructures

ITHACA, NY | Posted on June 26th, 2008

The method involves coating metal nanoparticles -- about 2 nanometers (nm) in diameter -- with an organic material known as a ligand that allows the particles to be dissolved in a liquid, then mixed with a block co-polymer (a material made up of two different chemicals whose molecules link together to solidify in a predictable pattern). When the polymer and ligand are removed, the metal particles fuse into a solid metal structure.

"The polymer community has tried to do this for 20 years," said Ulrich Wiesner, Cornell professor of materials science and engineering, who, with colleagues, reports on the new method in the June 27 issue of the journal Science. "But metals have a tendency to cluster into uncontrolled structures. The new thing we have added is the ligand, which creates high solubility in an organic solvent and allows the particles to flow even at high density."

Another key factor, he added, is to make the layer of ligand surrounding each particle relatively thin, so that the volume of metal in the final structure is large enough to hold its shape when the organic materials are removed.

"This is exciting," Wiesner said. "It opens a completely novel playground because no one has been able to structure metals in bulk ways. In principle, if you can do it with one metal you can do it with mixtures of metals."

Wiesner and two Cornell colleagues, Francis DiSalvo, the J.A. Newman Professor of Chemistry and Chemical Biology, and Sol Gruner, the John L. Wetherill Professor of Physics, as well as other researchers, report in Science how they used the new method to create a platinum structure with uniform hexagonal pores on the order of 10 nm across (a nanometer is the width of three silicon atoms). Platinum is, so far, the best available catalyst for fuel cells, and a porous structure allows fuel to flow through and react over a larger surface area.

The researchers began by mixing a solution of ligand-coated platinum nanoparticles with a block co-polymer. The solution of nanoparticles combines with just one of the two polymers. The two polymers assemble into a structure that alternates between small regions of one and the other, in this case producing clusters of metal nanoparticles suspended in one polymer and arranged around the outside of hexagonal shapes of the other polymer. Many other patterns are possible, depending on the choice of polymers.

The material is then annealed in the absence of air, turning the polymers into a carbon scaffold that continues to support the shape into which the metal particles have been formed. Wiesner and colleagues have previously used the carbon scaffold approach to create porous nanostructures of metal oxides.

The final step is to heat the material to a higher temperature in air to oxidize the ligands and burn away the carbon. Metal nanoparticles have a very low melting point at their surface, so the particles sinter together into a solid metal structure. The researchers have made fairly large chunks of porous platinum this way, up to at least a half-centimeter across.

In addition to making porous materials, the researchers said, the technique could be used to create finely structured surfaces, the key to the new field of plasmonics, in which waves of electrons move across the surface of a conductor with the information-carrying capacity of fiber optics, but in spaces small enough to fit on a chip.

####

For more information, please click here

Contacts:
234 Day Hall
Ithaca, NY 14853
607-255-6074

Copyright © Cornell University Communications

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Princeton-led team discovers unexpected quantum behavior in kagome lattice:Experiments suggest evidence for novel patterns of electronic charge distribution in a kagome material whose handedness can be manipulated with a magnetic field June 18th, 2021

Atomic-scale tailoring of graphene approaches macroscopic world June 18th, 2021

Compact quantum computer for server centers: Researchers build smallest quantum computer yet based on industry standards June 18th, 2021

Changing a 2D material's symmetry can unlock its promise: Jian Shi Research Group engineers material into promising optoelectronic June 18th, 2021

Chip Technology

Researchers tame silicon to interact with light for next-generation microelectronics June 11th, 2021

Rice lab peers inside 2D crystal synthesis: Simulations could help molecular engineers enhance creation of semiconducting nanomaterials June 11th, 2021

Magnetism drives metals to insulators in new experiment: Study provides new tools to probe novel spintronic devices June 4th, 2021

New form of silicon could enable next-gen electronic and energy devices: Novel crystalline form of silicon could potentially be used to create next-generation electronic and energy devices June 4th, 2021

Discoveries

AI app could help diagnose HIV more accurately: Pioneering technology developed by UCL (University College London) and Africa Health Research Institute (AHRI) researchers could transform the ability to accurately interpret HIV test results, particularly in low- and middle-income June 18th, 2021

Atomic-scale tailoring of graphene approaches macroscopic world June 18th, 2021

Compact quantum computer for server centers: Researchers build smallest quantum computer yet based on industry standards June 18th, 2021

Changing a 2D material's symmetry can unlock its promise: Jian Shi Research Group engineers material into promising optoelectronic June 18th, 2021

Materials/Metamaterials

Novel liquid crystal metalens offers electric zoom June 17th, 2021

Active platinum species: Catalytic high-temperature oxidations: Individual atom or metal cluster? June 16th, 2021

New family of atomic-thin electride materials discovered June 11th, 2021

Researchers turned transparent calcite into artificial gold June 11th, 2021

Announcements

Proliferation of electric vehicles based on high-performance, low-cost sodium-ion battery:A large-capacity anode material is developed for sodium-ion batteries by using low-cost silicone-based oil. This process, if commercialized, is expected to significantly reduce manufacturing June 18th, 2021

AI app could help diagnose HIV more accurately: Pioneering technology developed by UCL (University College London) and Africa Health Research Institute (AHRI) researchers could transform the ability to accurately interpret HIV test results, particularly in low- and middle-income June 18th, 2021

Compact quantum computer for server centers: Researchers build smallest quantum computer yet based on industry standards June 18th, 2021

Changing a 2D material's symmetry can unlock its promise: Jian Shi Research Group engineers material into promising optoelectronic June 18th, 2021

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project