Carbon nanotube structures changed by 'attack' from within, researchers discover

Aug 16, 2011

(PhysOrg.com) -- A team of researchers involving scientists from The University of Nottingham has shown for the first time that chemical reactions at the nano-level which change the structure of carbon nanotubes can be sparked by an 'attack' from within.

The discovery challenges previous scientific thinking that the internal surface of the hollow nanostructures is chemically unreactive, largely restricting their use to that of an inert container or a ‘nano-reactor’ inside which other chemical reactions can take place.

Their research, published in the journal Nature Chemistry, shows that carbon nanotubes that have had their structures changed are exciting new materials that could be useful in the development of new technologies for gas storage devices, chemical sensors and parts of electronic devices such as transistors.

Dr Andrei Khlobystov, of the University’s School of Chemistry, who led the work at Nottingham, said: “It has universally been accepted for some time now that the internal surface of carbon nanotubes — or the concave side — is chemically unreactive, and indeed we have been successfully using carbon nanotubes as nano-reactors.

“However, in the course of this new research we made the serendipitous discovery that in the presence of catalytically active transition metals inside the nanotube cavity, the nanotube itself can be involved in unexpected .”

Carbon nanotubes are remarkable with a typical diameter of 1–2 nanometres, which is 80,000 times smaller than the thickness of a human hair. Dr Khlobystov and his research associates were recently involved in the discovery — published in Nature Materials — that nanotubes can be used as a catalyst for the production of nanoribbon, atomically thin strips of carbon created from carbon and sulphur atoms. These nanoribbons could potentially be used as new materials for the next generation of computers and data storage devices that are faster, smaller and more powerful.

In this latest research, the scientists found that an individual atom of Rhenium metal (Re) sets off a chemical reaction leading to the transformation of the inner wall of the nanotube. Initially, the attack by the Rhenium creates a small defect in the nanotube wall which then gradually develops into a nano-sized protrusion by ‘eating’ additional carbon atoms.

The protrusion then rapidly increases in size and seals itself off, forming a unique carbon structure dubbed a NanoBud, so called because the protrusion on the resembles a bud on a stem.

Previously, NanoBuds were believed to be formed outside the nanotube through reactions on the outer surface with molecules called fullerenes.

The new study demonstrates for the first time that they can be formed from within, provided that a transition metal atom with suitable catalytic activity is present within the nanotube.

In collaboration with the Electron Microscopy of Materials Science group at Ulm University in Germany, the scientists have even been able to capture ‘on camera’ the chemical reaction of the transition metal atom with the nanotube in real time at the atomic level using the latest Aberration-Corrected High Resolution Transmission Electron Microscopy (AC-HRTEM). Their videos show nanotubes with a diameter of around 1.5 nanometers, while the NanoBuds are just 1 nanometer across.

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User comments : 5

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Techno1
1.8 / 5 (5) Aug 16, 2011
Yeah, yeah, yeah. Once again, experimentalists make the theorists look like fools.

What else is new?

Do something useful with it now, please.
Ojorf
3.7 / 5 (6) Aug 16, 2011
If you have a lot of longish nanotubes with some buds close to the ends you could possibly make a long strong cable by binding them together using something resinish? The buds preventing the tubes from sliding out and past each other.
Sonhouse
not rated yet Aug 16, 2011
Yeah, yeah, yeah. Once again, experimentalists make the theorists look like fools.

What else is new?

Jesus are you jaded. No more than they announce a discovery you want it already to be commercialized. Why don't you show some patience instead of your obvious disdain? If you are so great, why don't YOU come up with uses? Oops, Ojorf already beat you to a possible use. Why don't you put your stupendous intellect on the job?

Do something useful with it now, please.

Techno1
1 / 5 (1) Aug 16, 2011
Sonhouse:

I already thought of some good uses for just this sort of thing in the past.

The Carbon nanotubes can be assembled like pipe-works to make nano-scaled scaffolding for 3-d computer technology.

It may everntually be possible to learn to manipulate these "buds" to serve as seed locations for nano-tubes connecting perpendicular to one another, which is exactly what would be needed.

In the past, I suggested using a fullerene structure to connect the nanotubes together,but if they can instead learn to make t's and elbos using some extension of this technique, that would be nearly idea.
Isaacsname
not rated yet Aug 16, 2011
Why use Rhenium ? It's been known for some time that it can degrade superalloys. Or are they just looking for worst-case scenarios ?

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