Navigation Links
The effects of hydrogen on growing carbon nanotubes
Date:10/5/2010

Washington, D.C. (October 5, 2010) -- Carbon nanotubes -- long, hollow cylinders of carbon billionths of a meter in diameter -- have many potential uses in nanotechnology, optics, electronics, and many other fields. The exact properties of nanotubes depend on their structure, and scientists as yet have little control over that structure, which is determined during the initial formation -- or growth -- of the nanotubes. In fact, says chemical engineer and materials scientist Eray Aydil of the University of Minnesota, "we do not know precisely how the nanotubes grow."

In a paper in the American Institute of Physics' Journal of Applied Physics, Aydil, professor of chemical engineering and materials science and the Ronald L. and Janet A. Christenson Chair in Renewable Energy, and his colleagues shed new light on the process. In particular, the researchers examined the influence of hydrogen gas.

"Carbon nanotubes grow from a metal catalyst particle that is immersed in a gas like methane," Aydil explains. "Sometimes hydrogen gas is also added and it was found that a little bit of hydrogen helps to grow carbon nanotubes with nice straight walls and with few defects. However, too much hydrogen addition gives fibers with thick walls, instead of nanotubes, or no growth at all."

To understand why, Aydil and colleagues used transmission electron microscopy and other methods to systematically image and characterize the effects of increasing concentrations of hydrogen. "It turns out that the iron metal catalysts turn to iron carbide by reacting with the carbon in methane. Iron carbide is a hard material that is not easily deformed, and carbon nanotubes grown from such catalysts tend to have nice straight walls," he says.

Adding more hydrogen to the mix causes iron carbide to turn into iron -- which is more malleable and ductile, and "deforms into shapes that give rise to more fiber-like structures rather than hollow carbon nanotubes," he says. At higher concentrations, hydrogen etches the forming carbon nanotubes, "and growth stops all together. It is the interaction of the hydrogen with the catalysts and its effect on the catalyst's structure that controls the carbon nanotube structure."


'/>"/>

Contact: Jason Sacrates Bardi
jbardi@aip.org
301-209-3091
American Institute of Physics
Source:Eurekalert

Related biology news :

1. Prolonged effects of a warming anomaly on grasslands
2. Effects of anthropogenic sound on marine mammals -- a research strategy
3. UC Riverside biochemists devise method for bypassing aluminum toxicity effects in plants
4. How to build crops that can beat aluminums toxic effects
5. Effects of climate change vary greatly across plant families
6. UNC, Yale partner to study effects of cocaine use on mother-infant relationships
7. Study reveals effects of unconscious exposure to advertisements
8. Climate change effects on imperiled Sierra frog examined
9. Ocean acidification could have broad effects on marine ecosystems
10. Stronger coastal winds due to climate change may have far-reaching effects
11. Chantix side effects no worse with depression history
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/8/2016)... Czech Republic , February 8, 2016 /PRNewswire/ ... EU-regulated global payment platform which presents innovation for ... Biometrics Authentication feature called VoiceKey. --> ... platform which presents innovation for clients, comfort and ... called VoiceKey. --> Worldcore ...
(Date:2/3/2016)... India , February 3, 2016 ... the new market research report "Automated Fingerprint Identification System ... Search, Latent Search), Application (Banking & Finance, Government, Healthcare, ... published by MarketsandMarkets, the market is expected to be ... CAGR of 21.0% between 2015 and 2020. The transformation ...
(Date:2/2/2016)... YORK , Feb. 2, 2016 ... of the bioinformatic market by reviewing the recent ... enabled tools that drive the field forward. Includes ... to: Identify the challenges and opportunities that ... providers and software solution developers, as well as ...
Breaking Biology News(10 mins):
(Date:2/10/2016)... New York, and New York, New York (PRWEB) , ... ... ... Regeneron Pharmaceuticals Inc. (NASDAQ: REGN) today announced that it ... and develop new vaccines and immunotherapies for infectious diseases and cancer. ...
(Date:2/10/2016)...  Matchbook, Inc., a company specializing in procurement ... announced today the appointment of Jim Shuman ... nearly 25 years of experience in supply chain, ... two decades in executive level roles as the ... and, most recently headed global logistics and procurement ...
(Date:2/10/2016)... , ... February 10, 2016 , ... LATHAM, NEW YORK... ... the SPIE Photonics West conference in San Francisco’s Moscone Center from February ... the same venue. , These latest InGaAs PIN diode standard packages feature a ...
(Date:2/10/2016)... ... February 10, 2016 , ... Curoverse announced today ... Azure, Arvados provides capabilities for managing and processing genomic and health data at ... major institutions collecting and analyzing genomic data,” said Adam Berrey chief executive officer ...
Breaking Biology Technology: