Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First metallic nanoparticles resistant to extreme heat

01.12.2009
Taking the Heat: Pitt Team Conquers Hurdle to Nano Devices With First Metallic Nanoparticles Resistant to Extreme Heat

Just as a gecko sheds its tail, metal-alloy particles endure 850 degrees Celsius by ditching weaker components, researchers report in Nature Materials

A University of Pittsburgh team overcame a major hurdle plaguing the development of nanomaterials such as those that could lead to more efficient catalysts used to produce hydrogen and render car exhaust less toxic. The researchers reported Nov. 29 in “Nature Materials” the first demonstration of high-temperature stability in metallic nanoparticles, the vaunted next-generation materials hampered by a vulnerability to extreme heat.

Götz Veser, an associate professor and CNG Faculty Fellow of chemical and petroleum engineering in Pitt's Swanson School of Engineering, and Anmin Cao, the paper's lead author and a postdoctoral researcher in Veser's lab, created metal-alloy particles in the range of 4 nanometers that can withstand temperatures of more than 850 degrees Celsius, at least 250 degrees more than typical metallic nanoparticles. Forged from the catalytic metals platinum and rhodium, the highly reactive particles work by dumping their heat-susceptible components as temperatures rise, a quality Cao likened to a gecko shedding its tail in self-defense.

“The natural instability of particles at this scale is an obstacle for many applications, from sensors to fuel production,” Veser said. “The amazing potential of nanoparticles to open up completely new fields and allow for dramatically more efficient processes has been shown in laboratory applications, but very little of it has translated to real life because of such issues as heat sensitivity. For us to reap the benefits of nanoparticles, they must withstand the harsh conditions of actual use.”

Veser and Cao present an original approach to stabilizing metallic catalysts smaller than 5 nanometers. Materials within this size range boast a higher surface area and permit near-total particle utilization, allowing for more efficient reactions. But they also fuse together at around 600 degrees Celsius-lower than usual reaction temperatures for many catalytic processes-and become too large. Attempts to stabilize the metals have involved encasing them in heat-resistant nanostructures, but the most promising methods were only demonstrated in the 10- to 15-nanometer range, Cao wrote. Veser himself has designed oxide-based nanostructures that stabilized particles as small as 10 nanometers.

For the research in “Nature Materials,” he and Cao blended platinum and rhodium, which has a high melting point. They tested the alloy via a methane combustion reaction and found that the composite was not only a highly reactive catalyst, but that the particles maintained an average size of 4.3 nanometers, even during extended exposure to 850-degree heat. In fact, small amounts of 4-nanometer particles remained after the temperature topped 950 degrees Celsius, although the majority had ballooned to eight-times that size.

Veser and Cao were surprised to find that the alloy did not simply endure the heat. It instead sacrificed the low-tolerance platinum then reconstituted itself as a rhodium-rich catalyst to finish the reaction. At around 700 degrees Celsius, the platinum-rhodium alloy began to melt. The platinum “bled” from the particle and formed larger particles with other errant platinum, leaving the more durable alloyed particles to weather on. Veser and Cao predicted that this self-stabilization would occur for all metal catalysts alloyed with a second, more durable metal.

Veser and Cao conducted their work with support from the National Energy Technology Laboratory, the lead research and development office for the U.S. Department of Energy's (DOE) Office of Fossil Energy, as well as the DOE's Office of Basic Energy Sciences and the National Science Foundation.

Morgan Kelly | EurekAlert!
Further information:
http://www.pitt.edu

More articles from Materials Sciences:

nachricht Physicists gain new insights into nanosystems with spherical confinement
27.07.2017 | Johannes Gutenberg Universitaet Mainz

nachricht Getting closer to porous, light-responsive materials
26.07.2017 | Kyoto University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>