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Membrane combines thinness with stability

ChemicalProcessing.com
03/29/2007

Membranes that consist of only a single layer of carbon atoms called graphene have been created by researchers at the Max Planck Institute for Solid State Research, Stuttgart, Germany, and the University of Manchester, Manchester, U.K. Despite their thinness, these graphene membranes remain extremely stable because they have a slightly corrugated form (see Figure 1), say the researchers.

The research team, headed by Jannik Meyer of the Max Planck Institute, form the membranes by putting ordinary graphite such as from a pencil onto a silicon crystal and then overlaying a metal scaffold made of thin gold wires with gaps between the wires 100 times smaller than the diameter of a human hair.

Dissolving the silicon leaves the graphene hanging freely on the scaffold. The resulting membrane has a surface of about 1 square micrometer but still contains 30 million carbon atoms.

“These two-dimensional membranes are completely different to ordinary three-dimensional crystals,” notes Meyer. “We have just begun to explore the fundamental properties and possible applications.” The membranes promise to have real-world applicability, says Andre Geim of the University of Manchester.

For instance, because the membranes are almost completely transparent to electrons, they may permit examination under an electron microscope of individual molecules absorbed on them and imaging of the atomic structure of complex biological molecules. The membranes also might suit filtration of gases. “It still remains a challenge, however, to be able to fabricate these membranes economically and on a larger scale,” Geim adds.