2D materials - Page 7

Researchers from Northwestern University have recently shown that graphene oxide paper can be made by mixing strong, solid GO flakes with weak, porous GO flakes. This finding may aid the production of higher quality GO materials, and also sheds light on a general problem in materials engineering: how to build a nano-scale material into a macroscopic material without losing its desirable properties.

Large single layers of GO wrinkle easily, leaving breakable gaps. Small, hard flakes don’t integrate well. image by Northwestern

To put it in human terms, collaboration is very important, said Jiaxing Huang, Northwestern Engineering professor of materials science and engineering, who led the study. Excellent players can still make a bad team if they don’t work well together. Here, we add some seemingly weaker players and they strengthen the whole team.

Project "HEA2D", which started in 2016 and set out to investigate the production, qualities, and applications of 2D nanomaterials, recently demonstrated end-to-end processing chain of two-dimensional nanomaterials. The project is a collaboration between AIXTRON, AMO, Coatema, Fraunhofer and Kunststoff-Institut für die mittelständische Wirtschaft (K.I.M.W.).

It was stated that the "HEA2D" consortium successfully demonstrated an end-to-end processing chain of two-dimensional nanomaterials as part of its results. 2D materials integrated into mass production processes have the potential to create integrated and systemic product and production solutions that are socially, economically and ecologically sustainable. Application areas for the technologies developed and materials investigated in this project are mainly composite materials and coatings, highly sensitive sensors, power generation and storage, electronics, information and communication technologies as well as photonics and quantum technologies.

Researchers from Brown and Columbia Universities in the U.S have demonstrated that unknown states of matter arise from stacking two-dimensional layers of graphene together. These new states have been named the fractional quantum Hall effect (FQHE), and are created through the complex interactions of electrons within and across graphene layers.

"In terms of materials engineering, this work shows that these layered systems could be viable in creating new types of electronic devices that take advantage of these new quantum Hall states," said Jia Li, assistant professor at Brown. Li added: "The findings show that stacking 2-D materials together in close proximity generates entirely new physics."

Spectroscopic Imaging Ellipsometry (SIE) is a powerful tool to characterize, analyze and investigate thicknesses, optical properties and defects or impurities of 2D-materials. Recently, researchers from the University of Cambridge, Accurion and the University of Applied Sciences and Arts in Gattingen Germany focused on ellipsometric contrast micrography (ECM), a fast intensity mode within spectroscopic imaging ellipsometry, and showed that it can be effectively used for noncontact, large area characterization of 2D materials like graphene to map coverage, layer number, defects and contamination.

The team has shown that imaging ellipsometry - in the mode of recording contrast micrographs - can be used to identify, test the quality and quantify 2D materials independently of the substrate and the material. Examples are graphene layers on Si with native oxide or directly on rough Cu catalyst foils as well as mono-layer hexagonal BN .

University of California, Berkeley, researchers have found that three carbon structures recently created by scientists in South Korea and Japan are in fact schwarzites, an elusive carbon structure which researchers predict will have unique electrical and storage properties like those of carbon nanotubes and graphene.

The new structures were built inside the pores of zeolites, crystalline forms of silicon dioxide—sand—more commonly used as water softeners in laundry detergents and to catalytically crack petroleum into gasoline. Called zeolite-templated carbons (ZTC), the structures were being investigated for possible interesting properties, though the creators were unaware of their identity as schwarzites, which theoretical chemists have worked on for decades.

Rice University researchers have found that fracture-resistant rebar graphene is more than twice as tough as pristine graphene. While on the two-dimensional scale, graphene is stronger than steel, its extremely thin nature makes it subject to ripping and tearing. Rebar graphene is the nanoscale analog of rebar (reinforcement bars) in concrete, in which embedded steel bars enhance the material’s strength and durability. Rebar graphene, developed by the Rice lab of chemist James Tour in 2014, uses carbon nanotubes for reinforcement.

In a new study, Rice materials scientist Jun Lou, graduate student and lead author Emily Hacopian and collaborators, including Prof. James Tour, stress-tested rebar graphene and found that nanotube rebar diverted and bridged cracks that would otherwise propagate in unreinforced graphene.

Paragraf, a Cambridge University graphene spin-out that focuses on the production of graphene and other 2D materials and the development of devices based on these materials, has announced the closure of a second tranche ‎within its seed funding round.

In September 2017, Paragraf closed a £2.64 million seed round to support the development of its first major products. The round was led by Cambridge Enterprise, the commercialization arm of the University of Cambridge, with the participation of Parkwalk Advisors, Amadeus Capital Partners, IQ Capital Partners, Martlet, the investment arm of Marshall of Cambridge Group, and a small group of angel investors. Now, a second tranche was closed, raising an additional sum of £260,000.

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Researchers from The City University of New York (CUNY) describe a process for creating diamene: flexible, layered sheets of graphene that temporarily become harder than diamond and impenetrable upon impact. The material is fascinating as it is as flexible and lightweight as foil but becomes stiff and hard enough to stop a bullet on impact. Such a material may be beneficial for applications like wear-resistant protective coatings and ultra-light bullet-proof films.

Photo by Red Orbit

The team worked to theorize and test how two layers of graphene could be made to turn into a diamond-like material upon impact at room temperature. The team also found the moment of conversion resulted in a sudden reduction of electric current, suggesting diamene could have interesting electronic and spintronic properties.

Researchers at the University of Arkansas, led by professor Paul Thibado, have found strong evidence that the internal motion of 2D materials could be used as a source of clean, limitless energy. The team has reportedly taken the first steps toward creating a device that can turn this energy into electricity, with the potential for many applications. A patent has recently been applied on this invention, called a Vibration Energy Harvester, or VEH.

The team studied the internal movements of carbon atoms in graphene and observed two distinct features: small Brownian motion and larger, coordinated movements. In these larger movements, the entire ripple buckled, flipping up and down like a thin piece of metal being repeatedly flexed. This pattern of small random motion combined with larger sudden movements is known as Lévy flights. This phenomenon can be observed in a variety of contexts, such as biomedical signals, climate dynamics, and more. Thibado is claimed to be the first to have observed these flights spontaneously occurring in an inorganic atomic-scale system.