Routes towards defect-free graphene

Feb 01, 2013
Optical micrograph of graphene domains formed across grain boundaries. Credit: Oxford University

A new way of growing graphene without the defects that weaken it and prevent electrons from flowing freely within it could open the way to large-scale manufacturing of graphene-based devices with applications in fields such as electronics, energy, and healthcare.

A team led by Oxford University scientists has overcome a key problem of growing graphene – a one atom-thick layer of carbon – when using an established technique called , that the tiny flakes of graphene form with random orientations, leaving defects or 'seams' between flakes that grow together.

The discovery, reported in a paper to be published in ACS Nano, reveals how these graphene flakes, known as 'domains', can be lined up by manipulating the alignment of carbon atoms on a relatively cheap – the of the acts as a 'guide' that controls the orientation of the carbon atoms growing on top of them.

A combination of control of this copper guide and the pressure applied during growth makes it possible to control the thickness of these domains, the geometry of their edges and the where they meet – 'seams' that act as obstacles to the smooth progress of electrons necessary to create efficient graphene-based electrical and .

'Current methods of growing flakes of graphene often suffer from graphene domains not lining up,' said Professor Nicole Grobert of Oxford University's Department of Materials who led the work. 'Our discovery shows that it is possible to produce large sheets of graphene where these flakes, called 'domains', are well-aligned, which will create a neater, stronger, and more 'electron-friendly' material.'

In principle the size of the sheet of graphene that can be created is only limited by the size of the copper base sheet.

SEM image of well-aligned hexagonal graphene domains. Credit: Oxford University

The Oxford-led team, which includes researchers from Forschungszentrum Juelich Germany, the University of Ioannina Greece, and Renishaw plc, has shown that it is also possible using the new technique to selectively grow bilayer domains of graphene – a double layer of closely packed – which are of particular interest for their unusual electrical properties.

'People have used copper as a base material before, but this is the first time anyone has shown that the many different types of copper surfaces can indeed strongly control the structure of graphene,' said Professor Grobert. 'It's an important step towards finding a way of manufacturing graphene in a controlled fashion at an industrial scale, something that is essential if we are to bridge the gap between fundamental research and building useful -based technologies.'

Explore further: Mirror-image forms of corannulene molecules could lead to exciting new possibilities in nanotechnology

More information: Controlling the Orientation, Edge Geometry, and Thickness of Chemical Vapor Deposition Graphene, ACS Nano: pubs.acs.org/doi/abs/10.1021/nn3049297

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User comments : 12

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antialias_physorg
1 / 5 (1) Feb 01, 2013
We've been hearing about graphene for a good while. But the mind still boggles when thinking that we may soon have square meter sheets of substances with perfectly aligned atoms only one atom thick.
Shakescene21
not rated yet Feb 01, 2013
Almost everything about graphene is mind-boggling -- every week someone announces a new property or application for the stuff. More than anything I'm thrilled with articles like this one, where someone has overcome a barrier to implementation or has achieved a major cost reduction.
harryhill
not rated yet Feb 01, 2013
The marvels of graphene seem to be unending. I get the feeling that it and Fusion Power are very closely related. Time wise that is.
ValeriaT
1 / 5 (1) Feb 01, 2013
The difference is, the graphene research is officially promoted, whereas the cold fusion research is hindered. You cannot compare two areas of research, one of which is getting grant support and it's peer reviewed, whereas the cold fusion has nearly no peer-reviewed publications in high-impact journals.
That is to say, these two areas of research may sound similar for laymans, because they're in similar situation by now - but they can actually evolve in the opposite trends.

IMO graphene is inconsistent with existing silicon-based technology of semiconductors, where the trend goes toward wide-gap materials (silicon carbide, diamond). It could get some other applications: conductive layers, filtering material for desalination, microwave filters or even some special discrete electronic components. But the CPU manufacturers seek quite different materials by now.
grondilu
not rated yet Feb 02, 2013
sorry. Remove this please.
antialias_physorg
1 / 5 (1) Feb 02, 2013
The difference is, the graphene research is officially promoted, whereas the cold fusion research is hindered.

That diffenernce only exists because people support stuff that demosntrably worls over stuff that demonstrably doesn't (wasn't there supposed to be cold fusion demonstrators and entire powerplants being shown last year? Somehow that didn't pan out. Surprise, surprise)

whereas the cold fusion has nearly no peer-reviewed publications in high-impact journals.

It did at one time. But when people found out it was crank science...well..scientific journals are for science. Not for fairy-bubble-gobbeldygook.
ValeriaT
1 / 5 (1) Feb 02, 2013
wasn't there supposed to be cold fusion demonstrators and entire powerplants being shown last year
This is another application of double standard, i.e. example of pathological skepticism. From when the validity of scientific findings is measured with proclamations of various individuals without any peer-revived publications?
because people support stuff that demonstrably works over stuff that demonstrably doesn't
String theory doesn't demonstrably work and it's supported. The cold fusion is demonstrated at MIT whole year and it's not supported. Why?
antialias_physorg
1 / 5 (1) Feb 02, 2013
String theory doesn't demonstrably work and it's supported.

String theory doesn't need support. Give a guy a pencil and he's all set to do work on string theory.
Cold fusion supposedly can generate lots of power - and it doesn't.

But if you're looking for support: your own link you posted in this very thread decrying that cold fusion was being actively hindered mentioned that NASA still works on it. So stop whining.
ValeriaT
1 / 5 (1) Feb 02, 2013
Cold fusion supposedly can generate lots of power - and it doesn't
It does. Prof. Hagelstein at MIT demonstrates the COP > 1000% routinely. NASA is merely trying to cover its own twenty years standing history of suppression of cold fusion research by now. It does not provide any useful output in form of publications, it rather tries to embrace the foreign know-how with patents.
antialias_physorg
1 / 5 (1) Feb 02, 2013
Prof. Hagelstein at MIT demonstrates the COP > 1000%

So power companies should be showeing him with money by now. So why does this need funding, again?

Oh wait - it needs funding because it's a fraud.
Steven_Anderson
1 / 5 (1) Feb 02, 2013
It's a sad thing cold fusion gets such attention, for a technology that has no route to a functioning model. If someone had the technology worked out. They would get a world wide patent for 100,000 with the backing of a angel investor which wouldn't be hard to find and then the next day they would be on Youtube with a demonstration in front of 1000 scientists. Go to http://rawcell.com and sign the second petition listed on the front page to research the LFTR Reactor technology in the US. India will have their first next year. China soon after.
RealScience
not rated yet Feb 02, 2013
@ValeriaT - the excess power is in tens of milliWatts, which it interesting but still within the range of chemical reactions.
The total excess energy over a day was just over a kilojoule, or as much as would be released in oxidizing ~0.06 grams of sugar, for example.
The experiment would have to be run for much longer to exclude chemical reactions.
Also a control with hydrogen rather than deuterium would help.
Also finding reaction products would help.

Until then it is interesting but not convincing.