Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Research of Empa scientists on the cover of "Nature": Synthesis of structurally pure carbon nanotubes using molecular seeds

Scanning tunneling microscopy images the precursor, the «folded» end cap, and the resulting carbon nanotube, together with the corresponding structural models. Source: Empa / Juan Ramon Sanchez Valencia
Scanning tunneling microscopy images the precursor, the «folded» end cap, and the resulting carbon nanotube, together with the corresponding structural models.

Source: Empa / Juan Ramon Sanchez Valencia

Abstract:
For the first time, researchers at Empa and the Max Planck Institute for Solid State Research have succeeded in "growing" single-wall carbon nanotubes (CNT) with a single predefined structure - and hence with identical electronic properties. And here is how they pulled it off: the CNTs "assembled themselves", as it were, out of tailor-made organic precursor molecules on a platinum surface, as reported by the researchers in the latest issue of the journal "Nature". In future, CNTs of this kind may be used in ultra-sensitive light detectors and ultra-small transistors.

Research of Empa scientists on the cover of "Nature": Synthesis of structurally pure carbon nanotubes using molecular seeds

Switzerland | Posted on August 7th, 2014

For 20 years, carbon nanotubes (CNTs) have been the subject of intensive fundamental as well as applied research. With their extraordinary mechanical, thermal and electronic properties, these tiny tubes with their graphitic honeycomb lattice have become the paragon of nanomaterials. They could help to create next-generation electronic and electro-optical components that are smaller than ever before, and thus to achieve even faster switching times.

As uniform as possible
With a diameter of roughly one nanometre, single-wall CNTs (or SWCNTs) need to be considered as quantum structures; the slightest structural changes, such as differences in diameter or in the alignment of the atomic lattice, may result in dramatic changes to the electronic properties: one SWCNT may be metallic, whilst another one with a slightly different structure is a semiconductor. Hence, there is a great deal of interest in reliable methods of making SWCNTs as structurally uniform as possible. In fact, corresponding synthesis concepts were formulated about 15 years ago. However, it is only now that surface physicists at Empa and chemists at the Max Planck Institute have successfully implemented one of these ideas in the laboratory. In the latest issue of "Nature", they describe how, for the first time, it has been possible to "grow" structurally homogenous SWCNTs and, hence, managed to clearly define their electronic properties.

For some time, the Empa team working under the direction of Roman Fasel, Head of the Laboratory at Empa and Professor of Chemistry and Biochemistry at the University of Berne, has been investigating the subject of "how molecules can be transformed or joined together to form complex nanostructures on a surface". For instance, by means of "bottom-up" synthesis, the Empa researchers managed to produce specific nanostructures such as defined chains of "buckyballs" (essentially, CNTs shrunk into ball form) or flat nanoribbons on gold substrates. "The great challenge was to find the suitable starting molecule that would also actually 'germinate' on a flat surface to form the correct seed," says Fasel, whose team has gained broad expertise in the field of molecular self-organisation over the years. Finally, their colleagues at the Max Planck Institute in Stuttgart successfully synthesised the suitable starting molecule, a hydrocarbon with no fewer than 150 atoms.

Molecular origami
Now how does the process actually work? In the first step, in a manner reminiscent of origami, the flat starting molecule must be transformed into a three-dimensional object, the germling. This takes place on a hot platinum surface (Pt(111)) by means of a catalytic reaction in which hydrogen atoms are split off and new carbon-carbon bonds are formed at very specific locations. The "germ" - a small, dome-like entity with an open edge that sits on the platinum surface - is "folded" out of the flat molecule. This "end cap" forms the "lid" of the growing SWCNT. In a second chemical process, further carbon atoms are attached, which originate from the catalytic decomposition of ethylene (C2H4) on the platinum surface. They position themselves on the open edge between the platinum surface and the end cap and raise the cap higher and higher; the nanotube grows slowly upwards. Only the germ defines the latter's atomic structure, as the researchers were able to demonstrate through the analysis of the vibration modes of the SWCNTs and scanning tunnel microscope (STM) measurements. Further investigations using the new scanning helium ion microscope (SHIM) at Empa show that the resulting SWCNTs reach lengths in excess of 300 nanometres.

t works!
Thus the researchers have proved that, by using made-to-measure molecular "germs", it is possible to clearly predefine the growth (and thus the structure) of long SWCNTs. The SWCNTs synthesised in this study are mirror-image symmetrical entities. However, depending on the manner in which the honeycombed atomic lattice is derived from the starting molecule ("straight" or "oblique" in relation to the CNT axis), it would also possible be possible to produce helically-wound nanotubes, i.e. nanotubes twisting to the right or left, which are not mirror-image symmetrical. And this very structure also determines the electronic, thermoelectric and optical properties of the material. Therefore, in principle, the researchers can produce materials with different properties in a targeted manner, by selecting the starting molecule.

As their next step, Fasel and his colleagues intend to gain an even better understanding of the way in which SWCNTs populate a surface. Although well over 100 million nanotubes per square centimetre are already grown on the platinum surface, actual "fully-grown" nanotubes only grow from a comparatively small proportion of the germs. This raises the questions: which processes are responsible for this, and how can the yield be increased?

####

For more information, please click here

Contacts:
Martina Peter

41-587-654-987

Copyright © EMPA

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 Links

Source: Nature,

You can find more pictures about SWCNTs on Empa’s Flickr-Stream:

Related News Press

News and information

Scientists find a way of acquiring graphene-like films from salts to boost nanoelectronics: Physicists use supercomputers to find a way of making 'imitation graphene' from salt July 30th, 2016

Vortex laser offers hope for Moore's Law: The optics advancement may solve an approaching data bottleneck by helping to boost computing power and information transfer rates tenfold July 30th, 2016

New method for making green LEDs enhances their efficiency and brightness July 30th, 2016

A new type of quantum bits July 29th, 2016

Laboratories

New nontoxic process promises larger ultrathin sheets of 2-D nanomaterials July 27th, 2016

New lithium-oxygen battery greatly improves energy efficiency, longevity: New chemistry could overcome key drawbacks of lithium-air batteries July 26th, 2016

An accelerated pipeline to open materials research: ORNL workflow system unites imaging, algorithms, and HPC to advance materials discovery and design July 24th, 2016

Scientists develop way to upsize nanostructures into light, flexible 3-D printed materials: Virginia Tech, Livermore National Lab researchers develop hierarchical 3-D printed metallic materials July 20th, 2016

Nanotubes/Buckyballs/Fullerenes

Easier, faster, cheaper: A full-filling approach to making nanotubes of consistent quality: Approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes July 19th, 2016

Sensing trouble: A new way to detect hidden damage in bridges, roads: University of Delaware engineers devise new method for monitoring structural health July 8th, 2016

Wireless, wearable toxic-gas detector: Inexpensive sensors could be worn by soldiers to detect hazardous chemical agents July 4th, 2016

Nanotubes' 'stuffing' as is: A scientist from the Lomonosov Moscow State University studied the types of carbon nanotubes' 'stuffing' June 2nd, 2016

Discoveries

Scientists find a way of acquiring graphene-like films from salts to boost nanoelectronics: Physicists use supercomputers to find a way of making 'imitation graphene' from salt July 30th, 2016

Vortex laser offers hope for Moore's Law: The optics advancement may solve an approaching data bottleneck by helping to boost computing power and information transfer rates tenfold July 30th, 2016

New method for making green LEDs enhances their efficiency and brightness July 30th, 2016

A new type of quantum bits July 29th, 2016

Announcements

Scientists find a way of acquiring graphene-like films from salts to boost nanoelectronics: Physicists use supercomputers to find a way of making 'imitation graphene' from salt July 30th, 2016

Vortex laser offers hope for Moore's Law: The optics advancement may solve an approaching data bottleneck by helping to boost computing power and information transfer rates tenfold July 30th, 2016

New method for making green LEDs enhances their efficiency and brightness July 30th, 2016

A new type of quantum bits July 29th, 2016

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Scientists find a way of acquiring graphene-like films from salts to boost nanoelectronics: Physicists use supercomputers to find a way of making 'imitation graphene' from salt July 30th, 2016

Vortex laser offers hope for Moore's Law: The optics advancement may solve an approaching data bottleneck by helping to boost computing power and information transfer rates tenfold July 30th, 2016

New method for making green LEDs enhances their efficiency and brightness July 30th, 2016

A new type of quantum bits July 29th, 2016

Nanobiotechnology

Scientists change properties of zeolites to improve hemodialysis July 29th, 2016

Starpharma initiates new DEP™ drug delivery program with AstraZeneca July 27th, 2016

Scientists test nanoparticle drug delivery in dogs with osteosarcoma July 26th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

Research partnerships

Vortex laser offers hope for Moore's Law: The optics advancement may solve an approaching data bottleneck by helping to boost computing power and information transfer rates tenfold July 30th, 2016

Lonely atoms, happily reunited July 29th, 2016

New lithium-oxygen battery greatly improves energy efficiency, longevity: New chemistry could overcome key drawbacks of lithium-air batteries July 26th, 2016

Ultrasensitive sensor using N-doped graphene July 26th, 2016

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic