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Chemists achieve breakthrough in the synthesis of graphene nanoribbons

graphene
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Graphene nanoribbons might soon be much easier to produce. An international research team led by Martin Luther University Halle-Wittenberg (MLU), the University of Tennessee and Oak Ridge National Laboratory in the U.S. has succeeded in producing this versatile material for the first time directly on the surface of semiconductors. Until now, this was only possible on metal surfaces. The new approach also enables scientists to customize the properties of the nanoribbons. Storage technology is one of the potential applications of the material. The research team reports on its results in the upcoming issue of Science.

For years, has been regarded as the material of the future. In simple terms, it is a two-dimensional carbon surface that resembles a honeycomb. This special structure gives the material distinctive properties: for example, it is extremely stable and ultra-light. There is a particular interest in graphene nanoribbons as they are a semiconductor material that could be used, for instance, in the electrical and computer industry. “This is why many research groups around the world are focusing their efforts on graphene nanoribbons,” explains chemist Professor Konstantin Amsharov at MLU. These ribbons, which are only nanometres in size, are made up of just a few carbon atoms wide. Their properties are determined by their shape and width. When graphene research was just beginning, the bands were produced by cutting up larger sections. “This process was very complicated and imprecise,” says Amsharov.

He and colleagues from Germany, the U.S. and Poland, have now succeeded in simplifying the production of the coveted nanoribbons. The team produces the material by joining together individual atoms, which enables the properties to be customized. The researchers have succeeded for the first time in producing the ribbons on the surface of titanium oxide, a non-metallic material. “Until now, the ribbons were mainly synthesized on gold surfaces. This is not only comparatively expensive, but also impractical,” explains Amsharov. The problem with this approach is that gold conducts electricity. This would directly negate the properties of the graphene nanoribbons, which is why this method has only been used in basic research. However, the gold was needed as a catalyst to produce the nanoribbons in the first place. In addition, the nanoribbons had to be transferred from the gold surface to another —a very tricky undertaking. The new approach discovered by Amsharov and his colleagues solves this set of problems.

“Our new method allows us to have complete control over how the are assembled. The process is technologically relevant as it could also be used at an industrial level. It is also more cost-effective than previous processes,” says Amsharov, in summary. There are numerous areas of application for the nanoribbons: they could be used in future storage and semiconductor technology and they play a crucial role in the development of quantum computers.



More information:
Rational synthesis of atomically precise graphene nanoribbons directly on metal oxide surfaces. Science (2020). science.sciencemag.org/cgi/doi … 1126/science.abb8880

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Martin-Luther-Universität Halle-Wittenberg

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Chemists achieve breakthrough in the synthesis of graphene nanoribbons (2020, June 25)
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NRL Chemists’ Rapid Response Cleans Up

WASHINGTON, May 29, 2020 /PRNewswire/ — The U.S. Naval Research Laboratory Chemistry Division researchers responded within four days to the Navy’s request in early April for Coronavirus (COVID-19) shipboard decontamination strategies.



200412-N-LH674-1007 APRA, Guam (April 12, 2020) U.S. Navy Aviation Electrician's Mate 3rd Class Kyle Hernandez, from Denton, Texas, assigned to the Tomcatters of Strike Fighter Squadron (VFA) 31, disinfects a berthing aboard the aircraft carrier USS Theodore Roosevelt (CVN 71). (U.S. Navy photo by Mass Communication Specialist Seaman Kaylianna Genier.)

The research team identified preferred chemistries and recommended products to disinfect large areas using commercially available products that were safe for the Sailors while minimizing the risk for causing shipboard corrosion.

Jim Wynne, a research chemist, led the efforts for the request. His expertise in surface decontamination directed the team to concentrate on the quaternary ammonium family of compounds. These compounds are known to exhibit broad-spectrum activity against a variety of pathogens at relatively low concentrations. They destroy microorganisms such as bacteria, fungi and viruses that cause harm to people.

These chemicals are commonly found in disinfectant wipes, sprays and other household cleaners designed to kill germs.

“Quaternary ammonium compounds were the most sensible solution for large area shipboard use, because they can effectively deactivate the virus by destroying its protein membrane,” Wynne said. “There are other chemicals that can be used to deactivate the virus, but they would be more corrosively aggressive to a ship’s delicate ecosystem.

“It’s always important to follow the manufacturer’s product guidelines. From my experience, these kind of disinfectants should reside on the surface about 10 minutes to be considered sanitized.”

The manner of application was also considered important for such large area decontamination. The researchers recommended the product be applied as a fine mist directly to compatible surfaces to ensure surfaces were adequately wetted while also not disturbing contamination that may be residing on the surface. The NRL team’s deep expertise of coating formulation, testing, and demonstration made the rapid response possible.

“Our extensive fundamental knowledge of chemical processes and the naval shipboard corrosion prevention risks and reduction led to the speedy recommendation,” said Ted Lemieux, a chemical engineer and head of the Center for Corrosion Science and Engineering.

Corrosion is a key concern for shipboard applications since ships employ a wide range of metals and nonmetals that are not normally found in household applications. These concerns also include electrical equipment and electronics that are not designed for some modes of disinfection such as fogging or misting.

The NRL Chemistry Division conducts basic and applied research and development to address critical Navy needs and advance the frontiers of physical, chemical, biological, and material science as well as nanoscience.

“Our focus on basic chemistries allowed us to spring into action when required,” said John Russell, Chemistry Division superintendent. “Our knowledge and awareness of the decontamination and corrosion issues helped us respond with recommendations that we knew would kill the virus, keep the Sailors safe, and not corrode component systems of the ship.”

About the U.S. Naval Research Laboratory 

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the Navy and Marine Corps from the seafloor to space and in the information domain. NRL headquarters is located in Washington, D.C., with major field sites in Stennis Space Center, Mississippi; Key West, Florida; and Monterey, California, and employs approximately 2,500 civilian scientists, engineers and support personnel.

By J. Raynel Koch, U.S. Naval Research Laboratory Corporate Communications

Media Contact:

J. Raynel Koch

nrlpao@nrl.navy.mil

(202) 424-9955 mobile



200412-N-LH674-1014 APRA, Guam (April 12, 2020) U.S. Navy Aviation Ordnanceman Airman Brian Miller, from Mineral Wells, Texas, assigned to the Black Knights of Strike Fighter Squadron (VFA) 154, disinfects a berthing aboard the aircraft carrier USS Theodore Roosevelt (CVN 71) with a multi-surface sanitizer. (U.S. Navy photo by Mass Communication Specialist Seaman Kaylianna Genier.)

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