In Nature Materials, a team led by Coleman (and funded by the UK-based firm Thomas Swan) describe how they took a high-power (400-watt) kitchen blender and added half a litre of water, 10–25 millilitres of detergent and 20–50 grams of graphite powder (found in pencil leads). They turned the machine on for 10–30 minutes. The result, the team reports: a large number of micrometre-sized flakes of graphene, suspended in the water.
Coleman adds, hastily, that the recipe involves a delicate balance of surfactant and graphite, which he has not yet disclosed (this barrier dissuaded me from trying it out; he is preparing a detailed kitchen recipe for later publication). And in his laboratory, centrifuges, electron microscopes and spectrometers were also used to separate out the graphene and test the outcome. In fact, the kitchen-blender recipe was added late in the study as a bit of a gimmick — the main work was done first with an industrial blender (pictured).
Still, he says, the example shows just how simple his new method is for making graphene in industrial quantities. Thomas Swan has scaled the (patented) process up into a pilot plant and, says commercial director Andy Goodwin, hopes to be making a kilogram of graphene a day by the end of this year, sold as a dried powder and as a liquid dispersion from which it may be sprayed onto other materials.
“It is a significant step forward towards cheap and scalable mass production,” says Andrea Ferrari, an expert on graphene at the University of Cambridge, UK. “The material is of a quality close to the best in the literature, but with production rates apparently hundreds of times higher.”
The quality of the flakes is not as high as that of the ones the winners of the 2010 Nobel Prize in Chemistry, Andre Geim and Kostya Novoselov from Manchester University, famously isolated using Scotch Tape to peel off single sheets from graphite. Nor are they as large as the metre-scale graphene sheets that firms today grow atom by atom from a vapour. But outside of high-end electronics applications, smaller flakes suffice — the real question is how to make lots of them.
Kitchen blenders aren’t the only way to produce reasonably high-quality flakes of graphene. Ferrari still thinks that using ultrasound to rip graphite apart could give better materials in some cases. And Xinliang Feng, from the Max Planck Institute for Polymer Research in Mainz, Germany, says that his recent publication, in the Journal of the American Chemical Society, reports a way to produce higher-quality, fewer-layer graphene at higher rates by electrochemical means. Coleman points out that Thomas Swan have taken the technique far beyond what is reported in the paper.