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Methane leak unlocks potential for revolutionary graphene production

Wed 18 Mar 2015

Graphene structure

Caltech scientists have today published a new technique for producing graphene at room temperature – ushered by an accidental methane leak – which could be critical for future commercial production of the material.

Graphene, the revolutionary atom-thick layer of carbon, is the thinnest compound ever created and is hailed for its incredible strength and conductivity capabilities. However, manufacturing the material has often been problematic, with scientists required to ‘grow’ graphene in furnaces reaching 1,000 degrees Celsius. These high temperatures frequently result in strain and deformation which compromises the material’s properties.

Today researchers at the California Institute of Technology in Pasadena have revealed a new method which will enable a faster and cooler production of high-quality graphene sheets.

boydandyeh

David Boyd, a Caltech staff scientist who helped develop the technique, said that previous methods seemed “barbaric” when compared to his accidental discovery in 2012.

“With this new technique, we can grow large sheets of electronic-grade graphene in much less time and at much lower temperatures,” said Boyd.

Boyd, along with Caltech physics professor Nai-Chang Yeh published a report today in the Nature Communications Journal titled ‘Single-Step Deposition of High-Mobility Graphene at Reduced Temperatures.’ It outlines a method whereby graphene can be grown in layers on top of each other, rather than in one layer, as is the case with current techniques.

“Previously people were only able to grow a few square millimetres of high-mobility graphene,” said Yeh. “Typically it takes about ten hours and nine to ten different steps to make a batch of high-mobility graphene using high-temperature growth methods. Our process involves one step and takes five minutes.”

According to market research group IDTechEx, the graphene industry could be valued at around $390mn (approx. £270mn) by 2024.

Boyd said that he has filed for at least three provisional patents for his production method, which he discovered by accident during a lunch break three years ago. On trying to recreate a graphene-manufacturing furnace technique, Boyd grew increasingly frustrated that such a simple method repeatedly produced charcoal – “It seemed like a very simple process. I even had better equipment than what was used in the original experiment, so it should have been easier for me.” Distracted by a phone call for 15 minutes, Boyd let a copper foil heat for longer than usual and returned to his experiment to find that two leaking valves had allowed traces of methane vapour to combine with his sample, creating graphene.

“It was an ‘A-ha!’ moment,” said Boyd. “I realized then that the trick to growth is to have a very clean surface, one without the copper oxide.”

After this chance happening, Boyd concentrated on improving the method with Caltech researchers to become the first group to invent a graphene which is stronger and more electrically-mobile than current industry standards.

For now the Caltech researchers have only built one centimetre squares of graphene using the new technique but are planning to develop sheets up to four inches thick, said Boyd. He added that the team will also start to explore the addition of other molecules and compounds to analyse different effects.

“Graphene is like a baby, and the world has yet to see its full-grown potential, especially in earthquake-prone California,” said Boyd. “You could imagine something crazy. You could wrap a building in graphene to keep it from falling over.”

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