Posts Tagged ‘Andre Geim’

Now fluorographene from Graphene Nobel winners

November 9, 2010

A new paper by the Graphene Nobel winners in the Journal Small:

Fluorographene: A Two-Dimensional Counterpart of Teflon, by Rahul R. Nair, Wencai Ren, Rashid Jalil, Ibtsam Riaz, Vasyl G. Kravets, Liam Britnell, Peter Blake, Fredrik Schedin, Alexander S. Mayorov, Shengjun Yuan, Mikhail I. Katsnelson, Hui-Ming Cheng, Wlodek Strupinski, Lyubov G. Bulusheva, Alexander V. Okotrub, Irina V. Grigorieva, Alexander N. Grigorenko, Kostya S. Novoselov, Andre K. Geim. Article first published online: 4 NOV 2010, DOI: 10.1002/smll.201001555

Abstract

A stoichiometric derivative of graphene with a fluorine atom attached to each carbon is reported. Raman, optical, structural, micromechanical, and transport studies show that the material is qualitatively different from the known graphene-based nonstoichiometric derivatives. Fluorographene is a high-quality insulator (resistivity >1012Ω) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting a Young’s modulus of 100 N m−1 and sustaining strains of 15%. Fluorographene is inert and stable up to 400 °C even in air, similar to Teflon.

Graphane crystal. This novel two-dimensional material is obtained from graphene (a monolayer of carbon atoms) by attaching hydrogen atoms (red) to each carbon atoms (blue) in the crystal. (Credit: Mesoscopic Physics Group, Prof. Geim - University of Manchester)

Science Daily. University of Manchester scientists have created a new material which could replace or compete with Teflon in thousands of everyday applications. Professor Andre Geim, who along with his colleague Professor Kostya Novoselov won the 2010 Nobel Prize for graphene — the world’s thinnest material, has now modified it to make fluorographene — a one-molecule-thick material chemically similar to Teflon.

Fluorographene is fully-fluorinated graphene and is basically a two-dimensional version of Teflon, showing similar properties including chemical inertness and thermal stability. Teflon is a fully-fluorinated chain of carbon atoms. These long molecules bound together make the polymer material that is used in a variety of applications including non-sticky cooking pans. The Manchester team managed to attach fluorine to each carbon atom of graphene. To get fluorographene, the Manchester researchers first obtained graphene as individual crystals and then fluorinated it by using atomic fluorine. To demonstrate that it is possible to obtain fluorographene in industrial quantities, the researchers also fluorinated graphene powder and obtained fluorographene paper.

Fluorographene turned out to be a high-quality insulator which does not react with other chemicals and can sustain high temperatures even in air.

Industrial scale production of fluorographene is not seen as a problem as it would involve following the same steps as mass production of graphene. The Manchester researchers believe that the next important step is to make proof-of-concept devices and demonstrate various applications of fluorographene. Professor Geim added: “There is no point in using it just as a substitute for Teflon. The mix of the incredible properties of graphene and Teflon is so inviting that you do not need to stretch your imagination to think of applications for the two-dimensional Teflon. The challenge is to exploit this uniqueness.”

 

Physics Nobel for graphene

October 5, 2010

What I thought might be the subject area of the Chemistry Nobel was in fact rewarded with the Physics Nobel prize today.

The Nobel Prize in Physics 2010 was awarded jointly to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene”

BBC: Andrei Geim and Konstantin Novoselov, both at Manchester University, UK, took the prize for research on graphene. Geim, 51, is a Dutch national while Novoselov, 36, holds British and Russian citizenship. Both are natives of Russia and started their careers in physics there.

Andre Geim

Andre Geim: Wikipedia

Graphene is a flat sheet of carbon just one atom thick; it is almost completely transparent, but also extremely strong and a good conductor of electricity. It consists of a hexagonal array of sp2-bonded carbon atoms, just like those found in bulk graphite. 2D materials display very interesting properties, and are fundamentally different from the 3D materials we encounter everyday. The discovery of 2D materials means that scientists now have access to materials of all dimensionalities, including 0D (quantum dots, atoms) and 1D (nanowires, carbon nanotubes).

Geim and Novoselov first isolated the fine sheets of graphene from graphite. A layer of graphite one millimetre thick actually consists of three million layers of graphene stacked on top of one another. The layers are weakly held together and are therefore fairly simple to tear off and separate. The researchers used ordinary sticky tape to rip off thin flakes from a piece of graphite. Then they attached the flakes to a silicon plate and used a microscope to identify the thin layers of graphene among larger fragments of graphite and carbon scraps.

Graphene can be used for many different purposes including transistors, gas sensors, support membranes for TEM and inert transparent coatings.

Konstantin Novoselov

Konstantin Novoselov : Photo: University of Manchester, UK

It provides the possibility for further research in quantum physics, relativity and has allowed the Klein paradox to be observed for the first time.

Some scientists have precicted that graphene could one day replace silicon – which is the current material of choice for transistors. It could also yield incredibly strong, flexible and stable materials and find uses in transparent touch screens or solar cells.

Ten years ago, Professor Geim and Professor Sir Michael Berry from the University of Bristol were jointly awarded an Ig Nobel prize for their experiments using magnetic fields to levitate live frogs.