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Graphene: a single carbon layer (source: Wikipedia)

There's a new and surprisingly simple way to make graphene, a single-layered sheet of carbon atoms arranged in honeycomb lattice with great strength and excellent electrical conductivity, according to a new UNSW study.

Graphene has been dubbed the hottest new material in nanotechnology for its many potential uses in electronics, including solar energy cells, transistors, liquid crystal displays and lithium batteries.

Until now, however, exploring that potential has been limited by practical problems in making the material cheaply and in quantity.

But in a new study published in the journal Nature Nanotechnology three researchers from the UNSW School of Chemistry - Mohammad Choucair, Pall Thordarson and John Stride - describe how they stumbled by chance on a much easier way while trying to make carbon nanotubes.

"We were as surprised as anyone," says Dr Stride, the team leader. "Only when we analysed this material did we realise that we had obtained carbon sheets. We then of course went back and repeated the procedure time and time again to optimise the approach."

Graphene can be produced painstakingly and expensively by ripping layers of carbon from a piece of graphite using adhesive tape - the so-called "Scotch Tape" method. Several research teams in the US, China and Ireland have recently reported ways to refine that process.

But the new method is far simpler. Sodium metal is reacted with ethanol under pressure, leaving a powdery white residue. The powder contains tiny pockets of ethanol: when it is heated rapidly it expands in what Stride calls a "popcorn effect", which appears to decompose the material down to elemental carbon.

The resulting fused array of graphene sheets is then dispersed by agitation with ultrasound.

"The most crucial aspect of the synthesis is the pyrolysis step and we have perfected this after many attempts," Dr Stride says. "The trick is to obtain an optimal power density within the sample whilst heating; this avoids charring or the production of graphitic lumps.

"In terms of scalability, an automated process could be envisaged given what we now know about the process."

Media contact:
Dr John Stride - j.stride@unsw.edu.au
Faculty of Science media liaison - Bob Beale - 0411 705 435 - bbeale@unsw.edu.au