Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A New Approach to Finding and Removing Defects in Graphene

07.06.2010
In a paper in Nature Chemistry, Vivek Shenoy and colleagues pinpointed noncarbon atoms that create defects when graphene is produced through a technique called graphene-oxide reduction. The researchers also propose how to make that technique more efficient by precisely applying hydrogen – rather than heat – to remove the impurities.

Graphene, a carbon sheet that is one-atom thick, may be at the center of the next revolution in material science. These ultrathin sheets hold great potential for a variety of applications from replacing silicon in solar cells to cooling computer chips.

Despite its vast promise, graphene and its derivatives “are materials people understand little about,” said Vivek Shenoy, professor of engineering at Brown University. “The more we can understand their properties, the more (technological) possibilities that will be opened to us.”

Shenoy and a team of U.S. researchers have gained new insights into these mysterious materials. The team, in a paper in Nature Chemistry, pinpoints the atomic configurations of noncarbon atoms that create defects when graphene is produced through a technique called graphene-oxide reduction. Building from that discovery, the researchers propose how to make that technique more efficient by outlining precisely how to apply hydrogen — rather than heat — to remove impurities in the sheets.

The sheets produced by graphene-oxide reduction are two-dimensional, honeycomb-looking planes of carbon. Most of the atoms in the lattice are carbon, which is what scientists want. But interwoven in the structure are also oxygen and hydrogen atoms, which disrupt the uniformity of the sheet. Apply enough heat to the lattice, and some of those oxygen atoms bond with hydrogen atoms, which can be removed as water. But some oxygen atoms are more stubborn.

Shenoy, joined by Brown graduate student Akbar Bagri and colleagues from Rutgers University and the University of Texas–Dallas, used molecular dynamic simulations to observe the atomic configuration of the graphene lattice and figure out why the remaining oxygen atoms remained in the structure. They found that the holdout oxygen atoms had formed double bonds with carbon atoms, a very stable arrangement that produces irregular holes in the lattice.

The oxygen atoms that form double bonds with carbon “have very low energy,” Shenoy said. “They’re unreactive. It’s hard to get them out.”

Now that they understand the configuration of the resistant oxygen atoms in the graphene, the researchers say adding hydrogen atoms in prescribed amounts and at defined locations is the best way to further reduce the graphene oxide. One promising technique, they write in the paper, is to introduce hydrogen where the oxygen atoms have bonded with the carbon atoms and formed the larger holes. The oxygen and hydrogen should pair up (as hydroxyls) and leave the lattice, in essence “healing the hole,” Shenoy said.

Another approach is to remove the oxygen impurities by focusing on the areas where carbonyls — carbon atoms that are double-bonded to oxygen atoms — have formed. By adding hydrogen, the researchers theorize, the oxygen atoms can be peeled away in the form of water.

The researchers next plan to experiment with the hydrogen treatment techniques as well as to investigate the properties of graphene oxide “in its own right,” Shenoy said.

The research was funded by the National Science Foundation and the Semiconductor Research Corporation’s Nanotechnology Research Initiative. Other authors on the paper include Cecilia Mattevi and Manish Chhowalla from Rutgers (both now at Imperial College in London), Muge Acik and Yves Chabal from the University of Texas–Dallas.

Richard Lewis | EurekAlert!
Further information:
http://www.brown.edu

More articles from Physics and Astronomy:

nachricht Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst

nachricht Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>