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Energy Efficiency researchers at Oak Ridge National Laboratory discover that hydrogen "herds" graphene grains into shape

Published on July 24th, 2011 | by Tina Casey

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Atomic-Level “Cowboy” Herds Graphene Grains into Shape

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July 24th, 2011 by
 
researchers at Oak Ridge National Laboratory discover that hydrogen "herds" graphene grains into shapeGraphene, the newly discovered material that is only one atom thick but two hundred times stronger than steel, could be put to infinite uses in the next generation of electronic devices, but getting graphene to behave is a little like herding cats…until now. A team of scientists at Oak Ridge National Laboratory has discovered that hydrogen can function like an atomic-scale cowboy, controlling the growth of graphene grains to form well defined, perfect hexagons.

Making Graphene

Graphene was discovered just a few years ago, and initial attempts to produce it were somewhat primitive. Researchers literally pressed a piece of tape over a piece of graphite to detach the single sheet of carbon atoms that form graphene (graphite is basically a stack of graphene sheets). Emerging tactics include  using water droplets to coax graphene into different shapes, and fabricating a coated paper and then chemically reducing it to produce uniform graphene sheets. The key sticking point is finding a method that works consistently and economically on a large, commercial scale.

Growing Graphene

More recently, researchers have begun to use vapor deposition to grow graphene on copper foil. The problem is, unlike natural graphene, the synthetic version consists of irregular, differently sized grains. The natural material has a distinctively uniform, chickenwire-like lattice structure that provides it with unique properties, including the ability to form nanoscale graphene bubbles.

 

Researchers at Oak Ridge National Laboratory discover hydrogen's role in growing graphene
Hydrogen gas controls the appearance of graphene grains (image courtesy ORNL).

The Oak Ridge Graphene Recipe

In the vapor deposition method, the substrate and the source of the carbon influence the shape and size of each graphene grain. The Oak Ridge researchers discovered a third variable in hydrogen, which previously had been thought to play a passive role in the process. Hydrogen helps to initiate the growth of the grains, and it also helps to eliminate weak bonds at the grain edges.

If the new method can be replicated on a mass scale, it would result in the introduction of a cheaper, lighter, stronger, and more functional material for use in semiconductors and hundreds if not thousands of electronic devices.

Read more about graphene:

Images: Cowboy by Sean MacEntee on flickr.com; Graphene grains courtesy of Oak Ridge National Laboratory.

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About the Author

Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



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