Graphene Gets a Teflon Makeover

Graphene Gets a Teflon Makeover

  1:31:00 AM    Science Lover

---

University of Manchester scientists have created a new material which could replace or compete with Teflon in thousands of everyday applications.

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)

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.

The results are reported in the advanced online issue of the journal Small. The work is a large international effort and involved research groups from China, the Netherlands, Poland and Russia.

The team hope that fluorographene -- a flat, crystal version of Teflon and is mechanically as strong as graphene -- could be used as a thinner, lighter version of Teflon, and also find applications in electronics, such as for new types of LED devices.

Graphene, a one-atom-thick material that demonstrates a huge range of unusual and unique properties, has been at the centre of attention since groundbreaking research carried out at The University of Manchester six years ago.

Its potential is almost endless -- from ultrafast transistors just one atom thick to sensors that can detect just a single molecule of a toxic gas and even to replace carbon fibres in high performance materials that are used to build aircraft.

Professor Geim and his team have exploited a new perspective on graphene by considering it as a gigantic molecule that, like any other molecule, can be modified in chemical reactions.

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.

One of the most intense directions in graphene research has been to open a gap in graphene's electronic spectrum, that is, to make a semiconductor out of metallic graphene. This should allow many applications in electronics. Fluorographene is found to be a wide gap semiconductor and is optically transparent for visible light, unlike graphene that is a semimetal.

Professor Geim said: "Electronic quality of fluorographene has to be improved before speaking about applications in electronics but other applications are there up for grabs."

Rahul Nair, who led this research for the last two years and is a PhD student working with Professor Geim, added: "Properties of fluorographene are remarkably similar to those of Teflon but this is not a plastic.

"It is essentially a perfect one-molecule-thick crystal and, similar to its parent, fluorographene is also mechanically strong. This makes a big difference for possible applications.

"We plan to use fluorographene an ultra-thin tunnel barrier for development of light-emitting devices and diodes.

"More mundane uses can be everywhere Teflon is currently used, as an ultra-thin protective coating, or as a filler for composite materials if one needs to retain the mechanical strength of graphene but avoid any electrical conductivity or optical opacity of a composite."

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."

Read More

Earth's Atmosphere Came from Outer Space, Scientists Find

Earth's Atmosphere Came from Outer Space, Scientists Find

  10:22:00 AM    Science Lover

---

The gases which formed the Earth's atmosphere -- and probably its oceans -- did not come from inside the Earth but from outer space, according to a study by University of Manchester and University of Houston scientists.

New research suggests that the gases which formed Earth's atmosphere -- and probably its oceans -- did not come from inside Earth but from outer space. (Credit: iStockphoto)

The report published in the journal Science means that textbook images of ancient Earth with huge volcanoes spewing gas into the atmosphere will have to be rethought.

According to the team, the age-old view that volcanoes were the source of the Earth's earliest atmosphere must be put to rest.

Using world-leading analytical techniques, the team of Dr Greg Holland, Dr Martin Cassidy and Professor Chris Ballentine tested volcanic gases to uncover the new evidence.

The research was funded by Natural Environment Research Council (NERC).

Read More

Carbon Capture Has A Sparkling Future, New Findings Show

Carbon Capture Has A Sparkling Future, New Findings Show

  9:39:00 PM    Science Lover

---

Carbon dioxide gas can dissolve in underground water
-- like bottled sparkling water.
(Credit: iStockphoto/Dirk Rietschel)

New research shows that for millions of years carbon dioxide has been stored safely and naturally in underground water in gas fields saturated with the greenhouse gas. The findings – published in Nature April 1 – bring carbon capture and storage a step closer.

Politicians are committed to cutting levels of atmospheric carbon dioxide to slow climate change. Carbon capture and storage is one approach to cut levels of the gas until cleaner energy sources are developed.

But the risks around the long-term storage of millions of cubic metres of carbon dioxide in depleted gas and oil fields has met with some concern, not least because of the possibility of some of the gas escaping and being released back to the atmosphere. Until now, researchers couldn't be sure how the gas would be securely trapped underground.

Naturally-occurring carbon dioxide can be trapped in two ways. The gas can dissolve in underground water – like bottled sparkling water. It can also react with minerals in rock to form new carbonate minerals, essentially locking away the carbon dioxide underground.

Previous research in this area used computer models to simulate the injection of carbon dioxide into underground reservoirs in gas or oil fields to work out where the gas is likely to be stored. Some models predict that the carbon dioxide would react with rock minerals to form new carbonate minerals, while others suggest that the gas dissolves into the water. Real studies to support either of these predictions have, until now, been missing.

To find out exactly how the carbon dioxide is stored in natural gas fields, an international team of researchers - led by the University of Manchester - uniquely combined two specialised techniques. They measured the ratios of the stable isotopes of carbon dioxide and noble gases like helium and neon in nine gas fields in North America, China and Europe. These gas fields were naturally filled with carbon dioxide thousands or millions of years ago.

They found that underground water is the major carbon dioxide sink in these gas fields and has been for millions of years.

Dr Stuart Gilfillan, the lead researcher who completed the project at the University of Edinburgh said: "We've turned the old technique of using computer models on its head and looked at natural carbon dioxide gas fields which have trapped carbon dioxide for a very long time."

"By combining two techniques, we've been able to identify exactly where the carbon dioxide is being stored for the first time. We already know that oil and gas have been stored safely in oil and gas fields over millions of years. Our study clearly shows that the carbon dioxide has been stored naturally and safely in underground water in these fields."

Professor Chris Ballentine of the University of Manchester, the project director, said: "The universities of Manchester and Toronto are international leaders in different aspects of gas tracing. By combining our expertise we have been able to invent a new way of looking at carbon dioxide fields. This new approach will also be essential for monitoring and tracing where carbon dioxide captured from coal-fired power stations goes when we inject it underground – this is critical for future safety verification."

Professor Barbara Sherwood Lollar of the University of Toronto and co-author of the study hopes the new data can be fed into future computer models to make modelling underground carbon capture and storage more accurate.

The work was funded by the Natural Environment Research Council and the Natural Sciences and Engineering Research Council of Canada.

==================================================================

Journal reference:

1. Stuart M. V. Gilfillan, Barbara Sherwood Lollar, Greg Holland, Dave Blagburn, Scott Stevens, Martin Schoell, Martin Cassidy, Zhenju Ding, Zheng Zhou, Georges Lacrampe-Couloume & Chris J. Ballentine. Solubility trapping in formation water as dominant CO₂ sink in natural gas fields. Nature, 2009; 458 (7238): 614 DOI: 10.1038/nature07852

Adapted from materials provided by Natural Environment Research Council, via EurekAlert!, a service of AAAS.

If you like this post, buy me a beer at $3!

Read More