Andre Geim And Konstantin Novoselov Find Surprising New Graphene Powers

A mysterious new property of graphene has been discovered by one of the British Nobel Prize-winning scientists who first created the "wonder material".

Graphene is an ultra-thin sheet of carbon just one atom thick.

In 2010, University of Manchester professors Andre Geim and Konstantin Novoselov won the physics Nobel prize for work that involved producing flakes of graphene using sticky tape. Both received knighthoods in the New Year Honours List.
Graphene is the thinnest material known and the strongest ever measured.

It also conducts electricity and heat better than any other material. Potential applications include fold-away mobile phones, wallpaper-thin lighting panels, and the next generation of aircraft.

Now a team led by Sir Andre has shown that graphene membranes shut out all gases and liquids except for water.

As far as water alone is concerned, they are "superpermeable". Water evaporates through a graphite membrane so fast it is as if no barrier was there at all.

The scientists studied membranes made from graphene oxide - graphene sheets peppered with other molecules. The sheets stack on top of each other to form strong, flexible laminates hundreds of times thinner than a human hair.

A metal container sealed with a graphite oxide film prevented air or any other gas, including helium, to leak out. But the researchers were surprised to find that it was no obstacle to water molecules.

"Helium gas is hard to stop," said Sir Andre. "It slowly leaks even through a millimetre-thick window glass but our ultra-thin films completely block it. At the same time, water evaporates through them unimpeded. Materials cannot behave any stranger."
The research, reported today in the journal Science, highlighted one immediate practical use for graphite oxide membranes - distilling alcohol.

"Just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time," said co-author Dr Rahul Nair. "Neither of us drinks vodka but it was great fun to do the experiment."

Sir Andre added: "The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water."