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World's First Verified Graphene Product™ Announced

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019

The world's first Verified Graphene Product™ has been approved by The Graphene Council.

MediaDevil’s CB-01 earphones make use of Nanene® graphene from Versarien in the CB-01’s audio diaphragm, enabling simultaneous optimisation of both the high and low-end audio frequencies. 

From FORBES:  "The detail the CB-01 earphones managed to squeeze from the music was captivating. These are remarkable."
 "...The CB-01 earphones from MediaDevil are a revelation. They are the first pair of graphene-coated earphones that made me sit up and take notice." 

Media Devil uses the finest materials and highly-skilled artisans to create premium quality products. These include full-grain European leather, Italian Rosewood, or precision engineered Aramid Fibre. And now Graphene, providing Media Devil customers with a unique experience.


Versarien (the supplier of Nanene™ graphene materials to Media Devil) is the first company in the world to pass the rigorous Verified Graphene Producer™ program administered by The Graphene Council.

This program involves an in-person inspection of graphene production facilities, analysis of random samples of graphene products and independent testing and characterization of the material by internationally recognized and qualified labs, such as the National Physical Laboratory (NPL) in the UK. 

Versarien uses proprietary materials technology to create innovative engineering solutions that are capable of having game-changing impact in a broad variety of industry sectors.

The Verified Graphene Producer™ and the Verified Graphene Product™ programs provide the world's most thorough, independent validation service, adding a level of transparency not available anywhere else and is based on the most up-to-date standards and testing protocols. 

This will be increasingly important to end-users and buyers of graphene as they search for reliable sources of supply.

 

Tags:  Graphene  Graphene Council  National Physical Laboratory  Versarien 

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XG Sciences and Perpetuus Partner to Supply Graphene to the North American Tire Markets

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019
XG Sciences, Inc., a market leader in the design and manufacture of graphene nanoplatelets and advanced materials containing graphene nanoplatelets, announced it has  entered into Commercialization and License Agreements with Perpetuus Advance Materials, a market leader in the production of dispersible, surface-modified graphene to optimize their performance in a range of matrices and end-use markets.

The Agreements provide the commercial framework allowing the two companies to more closely collaborate in the exclusive supply of functionalized graphene into the North American market and to also collaboratively develop applications for the global marketplace.  Initially, the Companies will focus efforts on elastomers, with an emphasis on tires and related applications, but may expand the relationship over time to include other markets and applications.  Under the Agreements, Perpetuus will locate one or more of its patented, plasma-based surfaces-modification production plants in the U.S. near one of XG Sciences’ graphene nanoplatelet production facilities.  The collaboration contemplates both product development collaboration and high-volume commercial supply.

First isolated and characterized in 2004, graphene is a single layer of carbon atoms. Among many noted properties, monolayer graphene is harder than diamonds, lighter than steel but significantly stronger, and conducts electricity better than copper. Graphene nanoplatelets are particles consisting of multiple layers of graphene with unique capabilities for energy storage, thermal conductivity, electrical conductivity, barrier properties, lubricity and the ability to impart physical property improvements when incorporated into plastics, metals or other matrices.

“We have been working with Perpetuus in various commercial and development efforts for the past several years.  This Agreement represents a key milestone in the commercial adoption of graphene and establishes XG Sciences and Perpetuus as marque players in the supply of graphene for use in tire elastomers and other applications,” said Dr. Philip Rose, CEO, XG Sciences. “The North American elastomer market, especially those used in tires is substantial.   Perpetuus has unique technology with demonstrated performance enhancements when incorporated into tires.  Tires will likely represent one of the break-out applications for graphene and we are now well-positioned with Perpetuus to deliver solutions to the elastomer market,” said Bamidele Ali, Chief Commercial Officer, XG Sciences.

“XG Sciences is a well-known leader in the graphene field and is an ideal choice with whom to partner to bring our technology to this important market,” said John Buckland, CEO, Perpetuus.

“We are familiar with XG Sciences’ graphene nanoplatelets and we have been utilizing them as input materials to our patented, surface-modification process and supplying the resulting high-performance graphenes to both commercial and developmental customers in a range of applications and markets.  It is a natural fit to partner our two Companies and leverage our respective capabilities to serve the North American market for elastomers,” said Ian Walters, Director and COO, Perpetuus.

Tags:  Bamidele Ali  energy storage  Graphene  Perpetuus Advanced Materials  Philip Rose  Tires  XG Sciences 

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Successful Share Purchase Plan Closes

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019
Advanced battery anode materials and graphene additives provider Talga Resources is pleased to advise its Share Purchase Plan (“SPP”) closed on Friday, 6 December 2019 after attracting strong participation, with demand for the SPP well in excess of the funds initially sought to be raised.

Talga has received applications under the SPP in excess of A$6.0 million. The Company had previously announced it was targeting A$3.0 million under the SPP, with the Talga Board having discretion to accept oversubscriptions above this limit.

In response to the strong shareholder support the Talga Board has decided that all eligible shareholders who applied for shares under the SPP will receive their full allocation of shares in accordance with the SPP terms and conditions.

The additional capital, beyond the initial target of A$3.0 million, will be used to enhance Talga’s financial flexibility as the Company progresses its short- and medium-term plans, including scaleup of Talnode®-C production for customer qualifications.

Talga Non-executive Chairman, Mr Terry Stinson: “Our aim with the Share Purchase Plan was to provide existing shareholders the opportunity to increase their holdings on the same terms as the recently completed institutional placement - with proceeds used towards funding the last stage of development prior to planned project funding for the Vittangi Graphite Anode Project.

The success of the SPP clearly demonstrates the continued strong support from our shareholders as we progress the execution of our vertically integrated battery anode and graphene additives business strategies. On behalf of the Company, I would like to thank shareholders for their continued support.”

In accordance with the SPP terms, the issue price of the new shares will be A$0.44 per share, being the same price as the issue of shares under the recently completed institutional placement (ASX:TLG 15 Nov 2019 and 21 Nov 2019).

The Company is working with its share registry Security Transfer Australia Pty Ltd to finalise the review of the SPP applications. New fully paid ordinary shares are expected to be issued to eligible applicants under the SPP on Friday, 13 December 2019, once processing of applications has been finalised.

Tags:  Graphene  Graphite  Talga Resources  Terry Stinson 

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Converting graphene into diamond film without high pressure

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019
Can two layers of graphene be linked and converted to the thinnest diamond-like material? Researchers of the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS, South Korea) have reported in Nature Nanotechnology ("Chemically Induced Transformation of CVD-Grown Bilayer Graphene into Fluorinated Single Layer Diamond") the first experimental observation of a chemically induced conversion of large-area bilayer graphene to the thinnest possible diamond-like material, under moderate pressure and temperature conditions.

This flexible, strong material is a wide-band gap semiconductor, and thus has potential for industrial applications in nano-optics, nanoelectronics, and can serve as a promising platform for micro- and nano-electromechanical systems.

Diamond, pencil lead, and graphene are made by the same building blocks: carbon atoms (C). Yet, it is the bonds’ configuration between these atoms that makes all the difference. In a diamond, the carbon atoms are strongly bonded in all directions and create an extremely hard material with extraordinary electrical, thermal, optical and chemical properties. In pencil lead, carbon atoms are arranged as a pile of sheets and each sheet is graphene. Strong carbon-carbon (C-C) bonds make up graphene, but weak bonds between the sheets are easily broken and in part explain why the pencil lead is soft. Creating interlayer bonding between graphene layers forms a 2D material, similar to thin diamond films, known as diamane, with many superior characteristics.

Previous attempts to transform bilayer or multilayer graphene into diamane relied on the addition of hydrogen atoms, or high pressure. In the former, the chemical structure and bonds’ configuration are difficult to control and characterize. In the latter, the release of the pressure makes the sample revert back to graphene. Natural diamonds are also forged at high temperature and pressure, deep inside the Earth. However, IBS-CMCM scientists tried a different winning approach.

The team devised a new strategy to promote the formation of diamane, by exposing bilayer graphene to fluorine (F), instead of hydrogen. They used vapors of xenon difluoride (XeF2) as the source of F, and no high pressure was needed. The result is an ultra-thin diamond-like material, namely fluorinated diamond monolayer: F-diamane, with interlayer bonds and F outside.

For a more detailed description; the F-diamane synthesis was achieved by fluorinating large area bilayer graphene on single crystal metal (CuNi(111) alloy) foil, on which the needed type of bilayer graphene was grown via chemical vapor deposition (CVD).

Conveniently, C-F bonds can be easily characterized and distinguished from C-C bonds. The team analyzed the sample after 12, 6, and 2-3 hours of fluorination. Based on the extensive spectroscopic studies and also transmission electron microscopy, the researchers were able to unequivocally show that the addition of fluorine on bilayer graphene under certain well-defined and reproducible conditions results in the formation of F-diamane. For example, the interlayer space between two graphene sheets is 3.34 angstroms, but is reduced to 1.93-2.18 angstroms when the interlayer bonds are formed, as also predicted by the theoretical studies.

“This simple fluorination method works at near-room temperature and under low pressure without the use of plasma or any gas activation mechanisms, hence reduces the possibility of creating defects,” points out Pavel V. Bakharev, the first author and co-corresponding author.

Moreover, the F-diamane film could be freely suspended. “We found that we could obtain a free-standing monolayer diamond by transferring F-diamane from the CuNi(111) substrate to a transmission electron microscope grid, followed by another round of mild fluorination,” says Ming Huang, one of the first authors.

Rodney S. Ruoff, CMCM director and professor at the Ulsan National Institute of Science and Technology (UNIST) notes that this work might spawn worldwide interest in diamanes, the thinnest diamond-like films, whose electronic and mechanical properties can be tuned by altering the surface termination using nanopatterning and/or substitution reaction techniques. He further notes that such diamane films might also eventually provide a route to very large area single crystal diamond films.

Tags:  2D material  bilayer graphene  Center for Multidimensional Carbon Materials  chemical vapor deposition  Graphene  Institute for Basic Science  Ming Huang  nanoelectronics  Nature Nanotechnology  Pavel V. Bakharev  Rodney S. Ruoff  semiconductor  Ulsan National Institute of Science and Technology 

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How to induce magnetism in graphene

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example, they may exhibit conducting, semiconducting or insulating behavior. However, one property has so far been elusive: magnetism. Together with colleagues from the Technical University in Dresden, Aalto University in Finland, Max Planck Institute for Polymer Research in Mainz and University of Bern, Empa researchers have now succeeded in building a nanographene with magnetic properties that could be a decisive component for spin-based electronics functioning at room temperature.

Graphene consists only of carbon atoms, but magnetism is a property hardly associated with carbon. So how is it possible for carbon nanomaterials to exhibit magnetism? To understand this, we need to take a trip into the world of chemistry and atomic physics. The carbon atoms in graphene are arranged in a honeycomb structure. Each carbon atom has three neighbors, with which it forms alternating single or double bonds. In a single bond, one electron from each atom – a so-called valence electron – binds with its neighbor; while in a double bond, two electrons from each atom participate. This alternating single and double bond representation of organic compounds is known as the Kekulé structure, named after the German chemist August Kekule who first proposed this representation for one of the simplest organic compound, benzene (Figure 1). The rule here is that electron pairs inhabiting the same orbital must differ in their direction of rotation – the so-called spin – a consequence of the quantum mechanical Pauli’s exclusion principle.

"However, in certain structures made of hexagons, one can never draw alternating single and double bond patterns that satisfy the bonding requirements of every carbon atom. As a consequence, in such structures, one or more electrons are forced to remain unpaired and cannot form a bond," explains Shantanu Mishra, who is researching novel nanographenes in the Empa nanotech@surfaces laboratory headed by Roman Fasel. This phenomenon of involuntary unpairing of electrons is called "topological frustration". But what does this have to do with magnetism?

The answer lies in the "spins" of the electrons. The rotation of an electron around its own axis causes a tiny magnetic field, a magnetic moment. If, as usual, there are two electrons with opposite spins in an orbital of an atom, these magnetic fields cancel each other. If, however, an electron is alone in its orbital, the magnetic moment remains – and a measurable magnetic field results. This alone is fascinating. But in order to be able to use the spin of the electrons as circuit elements, one more step is needed. One answer could be a structure that looks like a bow tie under a scanning tunneling microscope. Two frustrated electrons in one molecule Back in the 1970s, the Czech chemist Erich Clar, a distinguished expert in the field of nanographene chemistry, predicted a bow tie-like structure known as "Clar's goblet" (Figure 1). It consists of two symmetrical halves and is constructed in such a way that one electron in each of the halves must remain topologically frustrated. However, since the two electrons are connected via the structure, they are antiferromagnetically coupled – that is, their spins necessarily orient in opposite directions. In its antiferromagnetic state, Clar's goblet could act as a "NOT" logic gate: if the direction of the spin at the input is reversed, the output spin must also be forced to rotate.

However, it is also possible to bring the structure into a ferromagnetic state, where both spins orient along the same direction. To do this, the structure must be excited with a certain energy, the so-called exchange coupling energy, so that one of the electrons reverses its spin. In order for the gate to remain stable in its antiferromagnetic state, however, it must not spontaneously switch to the ferromagnetic state. For this to be possible, the exchange coupling energy must be higher than the energy dissipation when the gate is operated at room temperature. This is a central prerequisite for ensuring that a future spintronic circuit based on nanographenes can function faultlessly at room temperature. From theory to reality So far, however, room-temperature stable magnetic carbon nanostructures have only been theoretical constructs. For the first time, the researchers have now succeeded in producing such a structure in practice, and showed that the theory does correspond to reality. "Realizing the structure is demanding, since Clar's goblet is highly reactive, and the synthesis is complex," explains Mishra. Starting from a precursor molecule, the researchers were able to realize Clar’s goblet in ultrahigh vacuum on a gold surface, and experimentally demonstrate that the molecule has exactly the predicted properties.

Importantly, they were able to show that the exchange coupling energy in Clar’s goblet is relatively high at 23 meV (Figure 2), implying that spin-based logic operations could therefore be stable at room temperature. "This is a small but important step toward spintronics," says Roman Fasel. Spintronics Spintronics – composed of the words "spin" and "electronics" is a field of research in nanotechnology. The aim is to create electronics in which information is not coded with the electrical charge of electrons, as is the case in conventional semiconductor circuits, but with their magnetic moment caused by the rotation of the electron ("spin"). The electron spin is a quantum mechanical property – a single electron can have not only a fixed state "spin up" or "spin down", but a quantum mechanical superposition of these two states. In the future, spintronics could therefore not only enable further miniaturization of electronic circuits, but could also make electrical switching elements with completely new, previously unknown properties a reality.

Tags:  Aalto University  August Kekule  Graphene  Journal Nature Nanotechnology  magnetism  Max Planck Institute for Polymer Research  nanographene  nanotechnology  Technical University  University of Bern 

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ZEN Graphene Solutions Announces Offering of Flow-Through Shares

Posted By Graphene Council, The Graphene Council, Wednesday, December 11, 2019
ZEN Graphene Solutions announces that subject to TSX Venture Exchange acceptance, it has arranged an offering of flow-through common shares of the company on a non-brokered private placement basis. The offering comprises up to 2.5 million flow-through common shares of the company at a price of 40 cents per flow-through common share for gross proceeds of up to $1-million. The proceeds from the offering will be used to continue work on the environmental assessment and for community engagement.

All securities issued to purchasers under the offering will be subject to a four-month hold period from the closing date of the offering, pursuant to applicable securities legislation and policies of the exchange. Finders' fees may be paid, as permitted by exchange policies and applicable securities law.

ZEN hires Alphabet Creative

ZEN has hired Alphabet Creative for web services including building its webstore on the Shopify global platform to deliver an exceptional customer experience when they purchase graphene products from the company. Under the agreement, ZEN will issue shares for debt in the sum of $17,000 at a deemed value of $0.36 per share.

Tags:  Graphene  ZEN Graphene Solutions 

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Airbus-Backed European Project Could Produce Safer Aircraft

Posted By Graphene Council, The Graphene Council, Monday, December 9, 2019
If ice accumulates on the wings, propellers or other surfaces of an aircraft, control can be dangerously inhibited. Thermoelectric ice protection systems prevent this from happening, using an ultra-thin conductive coating layer to generate heat when current is applied. Could existing technology for this application be improved? The graphene-based thermoelectric ice protection system (GICE) Spearhead Project, announced by the Graphene Flagship, is set to advance the technology readiness of graphene in thermoelectric ice protection systems.

Graphene is an ideal material to keep aircraft parts ice free, without affecting aerodynamic properties. Based on the work performed by various partners of the Graphene Flagship during earlier research phases, graphene-based ice protection systems are already in development, albeit at a low technology readiness level.

The goal of the newly launched GICE project is to advance these technologies to higher maturity by developing three technology demonstrators for specific use cases needed by key industrial partners, including Airbus and Sonaca.

Airbus is the largest European aerospace OEM and Sonaca is a strategic tier-1 supplier of components for Airbus, providing the ideal launch pad for the commercialisation of graphene-based ice protection systems.

"Thermoelectric ice protection technologies currently under investigation are based on carbon black, carbon rovings, carbon nanotubes, or metallic heating wires," explained Fabien Dezitter, Icing expert at Airbus and GICE leader. "They all have advantages and disadvantages with respect to each other, but we expect that the graphene-based solution proposed by GICE could bundle most advantages of all thermoelectric solutions.

"Advantages of graphene include flexibility of integration into complex 3D structures, low weight, reduced thermo-mechanical stress during heating cycles, higher efficiency with lower power consumption, no oxidation and chemical inertness and facile integrability into carbon fibre reinforced polymers, thermoplastics, or glass fibre reinforced polymers."

Graphene in these systems also enables precise control of heat generation to ensure the ice protection system is always at its optimum performance. These beneficial properties will help the GICE project improve the technology readiness of graphene in ice protection systems, with the final product based on the knowledge generated in the manufacturing of three demonstrators for real use cases, moving toward safer and environmentally friendlier flights.

Qualification and certification processes for new technologies in the aerospace sector are slow, which is why the GICE project endeavours to bring graphene ice protection systems up to technology readiness level six — with a system prototype demonstration tested in an icing wind tunnel by the end of the Spearhead Project in 2023.

Tags:  Airbus  carbon nanotubes  Graphene  Graphene Flagship  Sonaca  thermoelectric 

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Sustainable material for carbon dioxide capture

Posted By Graphene Council, The Graphene Council, Monday, December 9, 2019
In a joint research study from Sweden, scientists from Chalmers University of Technology and Stockholm University have developed a new material for capturing carbon dioxide. The new material offers many benefits – it is sustainable, has a high capture rate, and has low operating costs. The research has been published in the journal ACS Applied Materials & Interfaces.

Carbon Capture and Storage (CCS) is a technology that attracts a lot of attention and debate. Large investments and initiatives are underway from politicians and industry alike, to capture carbon dioxide emissions and tackle climate change. So far, the materials and processes involved have been associated with significant negative side effects and high costs. But now, new research from Chalmers University of Technology and Stockholm University in Sweden has demonstrated the possibility of a sustainable, low-cost alternative with excellent, selective carbon dioxide-capturing properties.

The new material is a bio-based hybrid foam, infused with a high amount of CO2-adsorbing ‘zeolites’ – microporous aluminosilicates. This material has been shown to have very promising properties. The porous, open structure of the material gives it a great ability to adsorb the carbon dioxide.

“In the new material, we took zeolites, which have excellent capabilities for capturing carbon dioxide, and combined them with gelatine and cellulose, which has strong mechanical properties. Together, this makes a durable, lightweight, stable material with a high reusability. Our research has shown that the cellulose does not interfere with the zeolites’ ability to adsorb carbon dioxide. The cellulose and zeolites together therefore create an environmentally friendly, affordable material,” says Walter Rosas Arbelaez, PhD student at Chalmers' Department of Chemistry and Chemical Engineering and one of the researchers behind the study.

Fits well with the ongoing developments within CCS and CCU

The researchers’ work has yielded important knowledge and points the way for further development of sustainable carbon capture technology. Currently, the leading CCS technology uses ‘amines’, suspended in a solution. This method has several problems – amines are inherently environmentally unfriendly, larger and heavier volumes are required, and the solution causes corrosion in pipes and tanks. Additionally, a lot of energy is required to separate the captured carbon dioxide from the amine solution for reuse. The material now presented avoids all of these problems. In future applications, filters of various kinds could be easily manufactured.

“This research fits well with the ongoing developments within CCS and CCU (Carbon Capture and Utilisation) technology, as a sustainable alternative with great potential. In addition to bio-based materials being more environmentally friendly, the material is a solid – once the carbon dioxide has been captured, it is therefore easier and more efficient to separate it than from the liquid amine solutions,” says Professor Anders Palmqvist, research leader for the study at Chalmers.

Overcoming a difficult obstacle – vital breakthrough

Zeolites have been proposed for carbon capture for a long time, but so far, the obstacle has been that ordinary, larger zeolite particles are difficult to work with when they are processed and implemented in different applications. This has prevented them from being optimally used. But the way the zeolite particles have been prepared this time – as smaller particles in a suspension – means they can be readily incorporated in and supported by the highly porous cellulose foam. Overcoming this obstacle has been a vital breakthrough of the current study.

“What surprised us most was that it was possible to fill the foam with such a high proportion of zeolites. When we reached 90% by weight, we realized that we had achieved something exceptional. We see our results as a very interesting piece of the puzzle in the search for a solution to the complex challenge of being able to reduce the amount of carbon dioxide in the Earth's atmosphere quickly enough to meet climate goals,” says Walter Rosas Arbelaez.

Tags:  ACS Applied Materials & Interfaces  Anders Palmqvist  Carbon Dioxide  Chalmers University of Technology  Graphene  Stockholm University  Walter Rosas Arbelaez 

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Solving the mystery of carbon on ocean floor

Posted By Graphene Council, The Graphene Council, Friday, December 6, 2019
For years, researchers looking at seafloor sediments would find bits of black carbon along with organic carbon strewn across the ocean floor, but they couldn't say exactly where it originated. The challenge with studying deep marine carbon is that it is a mixture of fresh material delivered from the surface and an aged component, the origin of which had been previously unknown.

Now, a new University of Delaware study recently published in Nature Communications shows for the first time that the old carbon found on the seafloor can be directly linked to submicron graphite particles emanating from hydrothermal vents.

Identifying the sources, transport pathways and the fate of this seafloor carbon is key to understanding the dynamics of the marine carbon cycle.

The ocean acts as a reservoir for substantial amounts of both organic carbon and carbon dioxide, which can lead to ocean acidification or be converted to form organic carbon via photosynthesis. Thus, it is important to understand how carbon moves between different phases in the ocean and how it might become sequestered in the deep ocean for extremely long periods of time. This work shows that organic carbon and carbon dioxide can also be converted at vents to another form of carbon, graphite.

The study was led by Emily Estes, a former post-doctoral researcher at UD who is now a staff scientist with the International Ocean Discovery Program at Texas A&M University, and George Luther, the Maxwell P. and Mildred H. Harrington Professor of Marine Chemistry and the Francis Alison Professor in UD's College of Earth, Ocean and Environment (CEOE).

To conduct their study, the researchers used samples of nanoparticles from five different hydrothermal vent sites collected during a research expedition to the East Pacific Rise vent field in the Pacific Ocean in 2017, funded by the National Science Foundation's marine geology and geophysics program.

Estes conducted shipboard sampling of hydrothermal vent fluids and particulates during the expedition, which was led by Luther.

When they got back from the research cruise and wanted to take a deeper look at what they collected, the samples were analyzed under scanning and transmission microscopes by colleagues at the National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth) at Virginia Tech.

Once they looked at the results, Estes noticed a large number of submicron graphite particles, similar to what would be found in an everyday lead pencil, in the samples.

While it's known that graphite can form hydrothermally in sediments, this study showed that these sub-micron particles of graphite that come out of the vents occur consistently across a range of vent environments, including both focused high temperature and low temperature venting sites.

"Even though our study is a preliminary observation of these particles, it suggests that they're probably very widespread and could be a significant source of this type of carbon to the deep ocean," said Estes.

Overlooked graphite
Previous studies may have overlooked the significance of graphite particles because of the way in which dissolved organic carbon and particulate organic carbon are measured.

Working with Andrew Wozniak, assistant professor in the School of Marine Science and Policy in CEOE, and Nicole Coffey, a master's level student in CEOE who was also on the research cruise as an undergraduate in 2017, Estes and Luther were able to show that common techniques used to measure dissolved organic carbon or particulate organic carbon also pick up graphite.

Because graphite is only made up of carbon, however, if somebody just did a generic carbon-14 measurement, they might overlook that there's hydrothermal graphite in their sample.

"Graphite is not carbon with hydrogen, oxygen, nitrogen and other elements," said Luther. "So here's an inorganic form of carbon, because it's pure carbon, that's also being measured as organic carbon, whether it's dissolved or particulate."

Finding these submicron graphite particles helps to answer a mystery that has confounded researchers with regards to dissolved organic carbon in really deep ocean environments.

"If you measure the carbon-14 age on it, it comes out to be a little bit older than you would actually expect and so there's been a mystery surrounding what the source of this old organic carbon is," said Estes. "We showed that vents emit this graphitic carbon."

Another important point of the paper is that because these graphite submicron particles are not dense and emit from the hydrothermal vents in flat sheet-like structures, they have the potential to get entrained into ocean currents and distributed far away from the vent sites. This will be important to take into consideration for future research in regards to the marine carbon cycle.

"The next steps will be trying to actually quantify how much carbon is coming out of the vents and then compare that to what we measure as dissolved organic carbon in the ocean and figure out what part of the flux it is," said Estes.

Tags:  Emily Estes  Francis Alison  George Luther  Graphene  Graphite  University of Delaware  Virginia Tech 

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Properties of graphene change due to water and oxygen

Posted By Graphene Council, The Graphene Council, Friday, December 6, 2019
We often find that food becomes rotten when we leave it outside for long and fruits turn brown after they are peeled or cut. Such phenomena can be easily seen in our daily life and they illustrate the oxidation-reduction reaction. The fundamental principle controlling physical properties of two-dimensional materials noted as next generation materials like graphene is found to be redox reactions.

The research team consisted of Professor Sunmin Ryu, Kwanghee Park, and Haneul Kang, affiliated with Department of Chemistry, POSTECH, discovered that the doping of two-dimensional materials with influx of charges from outside in the air is by an electrochemical reaction driven by the redox couples of water and oxygen molecules. Using real-time photoluminescence imaging, they observed the electrochemical redox reaction between tungsten disulfide and oxygen/water in the air. According to their study¸ the redox reaction can control the physical properties of two-dimensional materials which can be applied to bendable imaging element, high-speed transistor, next generation battery, ultralight material and other two-dimensional semiconductor applications.

Two-dimensional materials like graphene and tungsten disulfide are in the form of a single or few layers of atoms in nanometer size. They are thin and easily bended but hard. Because of these properties, they are used in semiconductors, display, solar battery and more and, they are called as a dream material. However, since all atoms exist on the surface of a material, it is limited to the ambient environment such as temperature and humidity which often causes them to modify or transform. Before the research team announced on the result of their study, it has been unknown why such phenomenon happens and has been difficult to commercialize, being unable to control material properties.

The research team used real-time photoluminescence imaging of tungsten disulfide and Raman spectroscopy of graphene. They demonstrated molecular diffusion through the two-dimensional nanoscopic space between two-dimensional materials and hydrophilic substrates. They also discovered that there was enough amount of water to mediate the redox reactions in the space. Furthermore, they proved that charge doping in the acid such as hydrochloric acid is also dictated by dissolved oxygen and hydrogen-ion concentration (pH) in the same way.

What they have accomplished in this research is the fundamental principle needed to govern electrical, magnetic, and optical properties of two-dimensional or other low-dimensional materials. It is anticipated that this method can be applied to improve pretreatment which is needed to prevent two-dimensional materials from being modified by surroundings and aftertreatment technology such as encapsulation for flexible and stretchable displays.

Professor Sunmin Ryu said, "Using the real-time photoluminescence, we were able to demonstrate that the electrochemical reaction driven by the redox couples of oxygen and water molecules in the air is the key and proved the fundamental principle for governing properties of materials. This reaction is applied to not only two-dimensional materials but also other low-dimensional materials such as quantum dot and nanowires. So, our findings will be an important steppingstone to development of nano technology based on low-dimensional materials."

Tags:  2D materials  Battery  Graphene  Haneul Kang  Kwanghee Park  POSTECH  semiconductor  Sunmin Ryu  transistor 

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