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Graphene reinforced carbon fibers

Posted By Graphene Council, Saturday, April 25, 2020
The superlative strength-to-weight ratio of carbon fibers (CFs) can substantially reduce vehicle weight and improve energy efficiency. However, most CFs are derived from costly polyacrylonitrile (PAN), which limits their widespread adoption in the automotive industry. Extensive efforts to produce CFs from low cost, alternative precursor materials have failed to yield a commercially viable product. Here, we revisit PAN to study its conversion chemistry and microstructure evolution, which might provide clues for the design of low-cost CFs. We demonstrate that a small amount of graphene can minimize porosity/defects and reinforce PAN-based CFs. 

Our experimental results show that 0.075 weight % graphene-reinforced PAN/graphene composite CFs exhibits 225% increase in strength and 184% enhancement in Young’s modulus compared to PAN CFs. Atomistic ReaxFF and large-scale molecular dynamics simulations jointly elucidate the ability of graphene to modify the microstructure by promoting favorable edge chemistry and polymer chain alignment.

Tags:  Graphene  Graphene Composite  Polymer 

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First Graphene to Proceed with Entitlement Issue to Fund Expansion

Posted By Graphene Council, Friday, April 24, 2020
Further to Monday’s announcement of a trading halt for a capital raising initiative, First Graphene Limited is pleased to advise it will proceed with a non- renounceable entitlement issue (“Entitlement Issue”).

Each participant in the non-renounceable entitlement will be issued one (1) New Share for every 10 Shares held by those Shareholders registered at the Record Date at an issue price of $0.13 per share, together with one (1) free attaching New Option for every one (1) Share subscribed for and issued (“Offer”). The New Options will be on the same terms as the existing series of listed options, which trade under the ticker FGROC.

The Offer is planned to raise up to $6,175,911 (based on the number of Shares on issue as at the date of this announcement), before costs. The Offer is not being underwritten.

Key dates for the Entitlement Issue, including the record date for determining entitlements, will be published as soon as practical.

Further information with respect to the Entitlement Issue will be disclosed in a prospectus, intended to be lodged with the ASIC as soon as possible, and mailed to eligible shareholders shortly after the record date. Shareholders may view the Company’s ASX announcements including those relating to the Offer on the ASX website under the ASX code FGR.

Funds from the Entitlement Issue will be used to expand and further automate the Company’s production facility, increase the marketing activities in Australia and accelerate its research and development on PureGRAPH® being incorporated into a new range of rubber and High-density polyethylene (HDPE) products.

Tags:  First Graphene  Graphene 

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3D printed tissue-like vascular structures investigated on Larmor

Posted By Graphene Council, Friday, April 24, 2020
An international team of scientists have discovered a new material that can be 3D printed to create tissue-like vascular structures.

Material platforms that exploit the functionalities of both proteins and graphene oxide offer exciting possibilities for the engineering of advanced materials. This study introduces a method to 3D print graphene oxide with a protein that can organise into tubular structures that replicate some properties of vascular tissue.

Self-assembly is the process by which multiple components can organise into larger well-defined structures. Biological systems rely on this process to controllably assemble molecular building-blocks into complex and functional materials exhibiting remarkable properties such as the capacity to grow, replicate, and perform robust functions.

Including graphene as a building-block could lead to the design of new biomaterials that benefit from its distinctive electronic, thermal, and mechanical properties. Graphene oxide is also gaining significant interest as a starting material; being used instead of graphene because its rich oxygen-containing functional groups can facilitate specific interactions with different molecules.

In this study, published in Nature Communications, a new biomaterial is made by the self-assembly of a protein with graphene oxide. The mechanism of assembly enables the flexible (disordered) regions of the protein to order and conform to the graphene oxide, generating a strong interaction between them. By controlling the way in which the two components are mixed, it is possible to guide their assembly at multiple size scales in the presence of cells and into complex robust structures.

"This work offers opportunities in biofabrication by enabling simultaneous top-down 3D bioprinting and bottom-up self-assembly of synthetic and biological components in an orderly manner from the nanoscale," explains researcher Professor Alvaro Mata; “Here, we are biofabricating micro-scale capillary-like fluidic structures that are compatible with cells, exhibit physiologically relevant properties, and have the capacity to withstand flow. This could enable the recreation of vasculature in the lab and have implications in the development of safer and more efficient drugs, meaning treatments could potentially reach patients much more quickly."

By using Small Angle Neutron Scattering (SANS) on Larmor alongside simulations and other experimental techniques, the group was able to describe the key steps of the underlying molecular mechanism. In particular, SANS facilitated the understanding of the unique protein-graphene oxide organization and establishment of the rules for turning these interactions into a supramolecular fabrication process.

The system they produced showed remarkable stability, robust assembly, biocompatibility, and bioactivity. These properties enable its integration with rapid-prototyping techniques to bio-fabricate functional microfluidic devices by directed self-assembly, opening new opportunities for engineering more complex and biologically relevant tissue engineered scaffolds, microfluidic systems, or organ-on-a-chip devices.

Tags:  3D Printing  Alvaro Mata  Biomaterials  Graphene  graphene oxide  Healthcare 

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Rolls-Royce chooses to partner with GEIC and 2-DTech

Posted By Graphene Council, Thursday, April 23, 2020
Versarien plc is pleased to announce that, following an open innovation call, multinational engineering company Rolls-Royce has selected to work with The University of Manchester's Graphene Engineering Innovation Centre and its Tier 1 partner, Versarien subsidiary, 2-DTech Limited.

The initial programme of work will use the state-of-the-art chemical vapour deposition (CVD) equipment located within the GEIC. The collaboration will look to explore, understand and create technological advances surrounding the use of graphene and other 2D materials used in wiring for next-generation aerospace engine systems.

The work conducted will seek to use the unique properties of these 2D materials to reduce the weight of electrical components, improve electrical performance and also increase resistance to corrosion of components in future engine systems.

The programme aims to present potential economic benefits, through the possibility of significant cost reductions, and global environmental benefits, through the reduction of energy use and lower emissions from electrification.

Neill Ricketts , Chief Executive of Versarien commented:
"The pursuit of sustainability has become an important goal for many companies in recent years. Rolls-Royce is one of the world's leading industrial technology companies and today, the size and impact of the markets its serves makes this task more urgent than ever. Taking advantage of advanced materials such as graphene, has the potential to revolutionise these markets and add real benefit.

" The partnership with Rolls-Royce is a significant endorsement to 2-DTech's work over the years and we are delighted it has been chosen by such a renowned business and look forward to working together."  

Dr Al Lambourne , Materials Specialist at Rolls - Royce, commented:
" Partnering with the GEIC and its members makes perfect sense to Rolls-Royce as we explore the opportunities and properties of a new class of 2D materials. Using the unique capabilities of 2-DTech and the GEIC we hope to address some of the challenges facing materials in the global aerospace industry , as we pioneer the electrification of future aircraft . "

James Baker, Graphene@Manchester CEO, commented:
"The GEIC is intended to act as an accelerator for graphene commercialisation, market penetration and in the creation of the material supply chain of graphene and 2D materials. It's great to see a company like Rolls-Royce partner with us and our other Tier 1 member, 2-DTech, to capitalise on our world-leading expertise and experience, along with specialist equipment, which will accelerate the product and process development and market entry."

Tags:  2D materials  2-DTech  Aerospace  Al Lambourne  chemical vapour deposition  corrosion  Graphene  Graphene Engineering Innovation Centre  James Baker  Neill Ricketts  Rolls-Royce  University of Manchester  Versarien 

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IIT Guwahati research team develops hierarchically structured graphene oxide nanosheets that can selectively separate oily or aqueous contaminates from respective emulsions

Posted By Graphene Council, Thursday, April 23, 2020
Researchers of Indian Institute of Technology Guwahati have developed a graphene-based superhydrophobic materials that can separate oil and water from both oil-in-water and water-in-oil emulsions, respectively.

Their work has recently been published in the Royal Society’s journal, Chemical Science. The research paper has been authored by Dr. Uttam Manna, Associate Professor, Department of Chemistry, IIT Guwahati, along with his research scholars Mr. Avijit Das, Mr. Kousik Maji, and Mr. Sarajit Naska.

Oil–water separation techniques have a number of industrial and environmental applications. Various porous and bulk substrates such as sponge that are made superhydrophobic, have been used to absorb oil from oil-water emulsions. The IIT Guwahati team has shown the efficacy of hierarchically structured graphene oxide nanosheets in removing oil or aqueous contaminates from respective emulsions, thereby effecting separation of oil and water.
Superhydrophobic materials – materials with extreme water repellence – are considered the best materials for removing oil from water, and they are being extensively studied for applications such as water purification and self-cleaning surfaces. The problem with superhydrophobic materials is that they are generally not scalable, or use environmentally toxic products such as fluorinated polymers/small molecules, or have poor mechanical and chemical stability. Moreover, the conventional spongy superhydrophobic materials are inherently less appropriate for separating oil-in-water emulsion due to poor accessibility of the dispersed oil droplets to the oil absorbing superhydrophobic interface.

“The hydrophobicity of materials is largely governed by the physical architecture and the chemical composition, and so such materials can be rationally created by combining low-surface-energy materials with hierarchical roughness”, explains Dr. Manna. This is exactly what the group has done in its quest for oil-water separating materials. They have manipulated graphene, a form of carbon, to have superhydrophobic properties suitable for separation of oil from water in emulsions.

The study of graphene for such applications is not unprecedented. Since the award of the Nobel prize to its creators in 2010, graphene – two dimensional structures of carbon – has been extensively studied for a variety of applications. Composed of pure carbon, graphene is similar to graphite but with characteristics that make it extraordinarily light and strong, giving it a moniker of “wonder material” in present day materials science research. Research all over the world have attempted to engineer the structure and composition of graphene to get surface roughness and low surface energy, suitable for use in applications that require superhydrophobicity. Such engineering is challenging and complicated.

The IIT Guwahati team has developed a facile method to produce graphene oxide-polymer composite with hierarchical topography and low surface energy chemistry in the confined space. Such graphene oxide species showed ‘confined-super- water-repellence’. They further deposited iron oxide nanoparticles on the two dimensional nanosheets, which made the entire material magnetically active.

“Our graphene oxide composites were able to separate oil from water in emulsions with high efficiency” says Dr. Manna. The uniqueness was that the separation could be brought about even under extremes of pH, salinity, surfactant contaminations etc., as is seen in real life scenarios. The IIT Guwahati’s graphene oxide species was capable of selectively soaking up tiny crude-oil droplets in oil-to-water emulsions with high absorption capacity (above 1000 wt%), as well as coalescing larger oil droplets of emulsions from water-in-oil emulsions.

“Further functionalization of this chemically/magnetically active 2D-nano-interface could help in the development of functional interfaces for various applications related to energy, catalysis and healthcare”, says Dr. Manna.

Tags:  2D materials  Graphene  graphene oxide nanosheets  Indian Institute of Technology Guwahati  nanoparticles  Uttam Manna  water purification 

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Multi-Functionalization of Graphene for Molecular Targeted Cancer Therapy

Posted By Graphene Council, Thursday, April 23, 2020
“Three” kinds of regalia such as crown, orb, and sward are often necessary to be a high king for conquering the world. For fighting off cancerous diseases, what do we need? This “triple” chemical modified nanomaterial might be save the patient.

Cancer is a leading cause of death worldwide. Under this situation, a successful tumor selective drug targeting and minimized toxicity of cancer drug are urgently necessary.

Scientists from Japan Advanced Institute of Science and Technology (JAIST) and Centre national de la recherche scientifique (CNRS), and their colleagues have developed a type of nanomedicine based on multi-functional graphene that allows for targeted cancer treatment at molecular level.

Single molecular sheet graphene is a promising carbon nanomaterial for various fundamental and practical applications in the next decade because of its excellent physico-chemical features. Graphene has been also known to have a good biocompatibility and biodegradability, thus leading to explore this nanocarbon as drug delivery carrier. However, it is not easy to modify a lot of individual functional molecules onto a graphene nano-sheet at the same time for its biomedical applications.

Developed by Prof. Eijiro Miyako from JAIST (Nomi, Japan), Dr. Alberto Bianco from CNRS (Strasbourg, France), and their international teams, the multi-functional graphene as a drug delivery carrier are successfully synthesized with “three” type of molecules such as near-infrared (NIR) fluorescent probe (indocyanine green; ICG), tumor targeting molecule (Folic acid: FA), and anticancer drug (doxorubicin; Dox) by a covalent chemical modification technique (Figure 1). ICG (green color part in the picture) was chosen as fluorophore to follow the uptake and to track the material inside the cells. FA (blue) was covalently bound through a polyethylene glycol (pink) linked to graphene, to specifically target the cancer cells, and Dox (red) was used as anticancer drug.

Aside from testing the therapeutic abilities to eliminate cancer cells in a culture dish, the team found that the unique properties of this multi-functional graphene showed an enhanced anticancer activity with excellent cancer targeting effect. This would open the doors to future biomedical applications of this type of material. The team plans to continue exploring multi-functional graphene towards the cancer therapy using murine animal model.

Paper titled “Rational chemical multifunctionalization of graphene interface enhances targeting cancer therapy”, published in Angewandte Chemie International Edition, DOI: 10.1002/anie.201916112

The work was supported by the Japan Society for the Promotion of Science KAKENHI Grant-in-Aid for Scientific Research (A) and (B), the KAKENHI Fund for the Promotion of Joint International Research, the Agence Nationale de la Recherche (ANR), the Graphene Flagship, the Spanish MINECO, the Generalitat Valenciana.

Tags:  Alberto Bianco  CNRS  Eijiro Miyako  Graphene  Healthcare  JAIST  nanomaterials 

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Global First as Talga Graphene Coating Begins Commercial-Scale Trial on Ocean-Going Cargo Vessel

Posted By Graphene Council, Thursday, April 23, 2020
Advanced battery anode materials and graphene additives provider Talga Resources Ltd is pleased to announce the commencement of a commercial scale trial of a Talga graphene-enhanced coating applied to a 33,000t container ship. The result is expected to be a range of environmental and economic benefits, which for marine applications includes improved corrosion resistance, decreased metallic paint loss into oceanic ecosystems and increased efficiency through lowering dry-docking cycles.

Believed to be the world’s largest single application of graphene, the 700 m2 coating of the cargo vessel’s hull is part of advanced testing of Talga’s functionalised graphene (Talphene®) additive as a performance booster for existing commercial marine coatings (part of the global 54 million tonne per annum paint and coating market1). The commercial-scale application follows completion of in-house development and patent pending technology that successfully translates graphene’s exceptional mechanical properties into paint and coatings. The result is expected to be a range of environmental and economic benefits, which for marine applications such as shipping and offshore infrastructure includes improved corrosion resistance, decreased metallic paint loss into oceanic ecosystems and increased efficiency through lowering dry-docking cycles.

The freshly coated ship is now at sea and over the coming 12-18 months the Talphene-coated area will be evaluated in the harsh real-life conditions of global cargo shipping.

Talga Managing Director, Mr Mark Thompson: “The maritime coating sector is a very large market and well suited to use of our Talphene® graphene additives for improved environmental and economic outcomes. Additionally, by successfully taking this new product from the laboratory to commercial scale application on a 33,000 tonne ship, being tested across global marine environments, we are showcasing our graphene’s real-world potential as a bulk industrial product.” Marine coatings market

Within the global ~54 million tonne per annum paint and coatings market2, the marine coatings segment is projected to grow to USD$12 Billion by 2024. Drivers for new coating technologies include environmental and regulatory demands, fuel efficiency, construction costs (pre-fabrication) and maintenance costs. Growth in emerging economies such as China, India and Brazil are large volume drivers while in terms of value, the Asia Pacific marine coatings market is projected to grow at the highest CAGR during the forecast period3. Key players operating in the marine coatings market include Hempel (Denmark), Jotun (Norway), AkzoNobel (Netherlands), PPG Industries (US), Sherwin-Williams (US), Chugoku Marine Paints (Japan), Nippon Paint (Japan), Kansai Paint (Japan), Axalta (US), and BASF Coatings (Germany).

Talphene® coating product development

Coatings are one of Talga’s key target products due to the large volume market and graphene’s potential to provide substantial new levels of performance and environmental sustainability. For maritime applications, Talga’s additive development has included multi-stage testing to optimise graphene loadings (i.e. quantities) and Talga’s unique patent-pending dispersion technology for epoxy based commercial primer coating systems. Testing by Talga included industry accepted ASTM prescribed Salt Fog Test (ASTM B117) where steel panels coated with epoxy primer containing Talphene additive showed improved corrosion protection performance compared to ‘state of the art’ commercial systems currently used world-wide in large volumes.

Further evaluation included mechanical performance tests, carried out to ASTM standard by the highly recognised research organisation The Welding Institute (TWI), as the coated surfaces of ships and maritime infrastructure are exposed to considerable abrasion and mechanical damage during service. The results showed a significant improvement in primer performance, including greater adhesion to the substrate (by ~7%), greater interlayer adhesion to the subsequent (antifouling) coating systems (by ~14%) and consistent improvement in abrasion resistance.

These improvements in performance were a notable outcome for this highly optimised industry, indicating that graphene’s exceptional mechanical properties translated into the coating system and warranted commercial-scale trials.

Commercial ship application & trial details

Based on the successful lab results, plans were drawn up for a major commercial scale application and sea trial. A 2-part epoxy based commercial coating system was purchased and mixed with the Talphene additive before dispatch to the ship management company for application during vessel dry docking (carried out every ~5 years for ships this size). The test areas along the ship’s starboard side, both below the water line and above in contact-wear sites, were blast cleaned to remove prior paint systems before the Talphene-enhanced primer coating was applied (next to a test reference coating without Talphene) in two coats, using manual spray systems. A major challenge of the product development was to translate the positive lab-scale tests into practical, large-volume use by on-site commercial applicators. The successful application of the Talphene-enhanced coating without any adverse effect in terms of stability in resin, application, curing and surface features is a highly positive step forward in the commercialisation process. The test areas have been over-coated with the standard topcoats used on the rest of the vessel and marked to ensure identification during service. Periodic inspection will be carried out over the next 12-18 months to determine real world performance.

Next steps

Talga intends to continue development of this Talphene additive for marine coatings under its range of paint and coating additives now trademarked as Talcoat™. The next steps include a trial of the additive as an after-market product, to be mixed into the coatings on-site by the commercial applicators, as opposed to being dispersed by Talga prior to despatch. Talga has also identified a range of potential commercial partners and commenced discussions, under NDA, regarding the incorporation of Talcoat products into their existing and new coating product lines4. The company notes that these negotiations are preliminary, and further updates will be released as and when any definitive commercial agreements are reached.

Tags:  Coatings  Corrosion  Graphene  Mark Thompson  Talga Resources 

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Next Level Analysis for Haydale Functionalised Nanomaterials

Posted By Graphene Council, Wednesday, April 22, 2020
Haydale, the global advanced materials group, has been awarded an Innovate UK Analysis for Innovators (A4I) project to explore the mechanisms by which the Haydale plasma functionalisation processes enables property improvements in polymers containing functionalised nanomaterials; properties such as mechanical strength, thermal, and electrical conductivity.

The project enables Haydale to gain access to world leading experts and cutting-edge facilities by collaborating with the National Physical Laboratory (NPL) and the Science and Technology Facilities Council (STFC) Hartree Centre.

The data produced in this project will help Haydale build on the significant progress it has already made in this area. It will enable Haydale to focusthe development of its entire product range; allowing quick and efficient selection of improved functionalisation chemistries that can optimise the performance of its current products.

Haydale has a range of plasma functionalised nanomaterial (HDPlas®) products which are dispersed in a variety of polymers to enhance customer products. Numerous developments conducted within Haydale have demonstrated that the use of its patented HDPlas® plasma technology is effective in imparting specific functional groupsto the nanomaterial surface for improved compatibility within the host polymer. This nanomaterial surface functionality leads to property enhancements in the final products above and beyond the use of un-functionalised nanomaterials.

This project aims to uncover this mechanism using a dual approach of advanced analytical techniques at NPL and modelling at STFC Hartree Centre. The approach of using analytical facilities with complementary modelling will ensure that the highest level of information is obtained, and that any conclusions are drawn with a high level of confidence and accuracy, thereby potentially enabling product and process development.

Keith Broadbent, Haydale CEO,said: “Haydale has a wealth of knowledge and expertise which hasled to the patenting of its HDPlas® functionalisation process. This analysis by both NPL and STFC will provide more data and practical understanding enabling us to further understand where our nanomaterials will provide benefit and continue to develop our unique processes to ensure we keep in the vanguard of this technology”

Barry Brennan, NPL Senior Research Scientist, said: “Understanding the chemistry of nanomaterials after industrial processing steps is crucial in determining the performance-enhancement in real-world products. We look forward to collaborating with Haydale on their functionalisation process.”

Tags:  Barry Brennan  Graphene  Haydale  Keith Broadbent  nanomaterial  National Physical Laboratory 

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Gratomic Announces Amendment to Terms of Convertible Debentures and Further Debt Settlement

Posted By Graphene Council, Wednesday, April 22, 2020
Gratomic Inc. wishes to announce that it has amended the terms of the Debenture Units announced in the Press Release issued April 8, 2020 in relation to its engagement of First Republic Capital Corporation ("First Republic") to act as its exclusive lead finder in respect of a non-brokered private placement to raise up to CAD $2,250,000 (the "Offering").

First Republic will act as exclusive lead finder on a commercially reasonable efforts basis to sell up to $1,500,000 aggregate principal amount of convertible debenture units ("Debenture Units") on the amended terms described herein. The Debenture Units will consist of up to 1,500 senior secured convertible debentures, with each Debenture Unit priced at $1,000 consisting of (a) one $1,000 face value convertible debenture, convertible at the option of the holder into common shares of the Company (a "Share") at $0.06 per Share for the first twelve (12) months from the closing of the Offering ("Closing Date"), and thereafter at $0.10 for a further six (6) months, which will bear interest at 10% per year, paid quarterly in cash, until maturity, being 18 months form the Closing Date (a "Debenture Certificate"); and (b) 8,333 share purchase warrants ("Debenture Warrants") with each Debenture Warrant entitling the holder to purchase one additional Share at an exercise price of $0.10 per Share for a period of 18 months from the Closing Date. See the April 8, 2020 Press Release for further details of the Offering.

The Company also wishes to announce that it will settle an aggregate of a further $149,606.75 of debt owed to arm's length parties, one director and two entities related to insiders of the Company for the issuance of 2,493,444 Shares of the Company at a price of $0.06 per share (the "Further Debt Settlement").

All securities issued pursuant to the Offering and the Further Debt Settlement are subject to a statutory hold period of four months and a day following the Closing Date.

Closing of the Offering is expected to occur on or before mid-May 2020. The Offering and Further Debt Settlement are subject to certain conditions, including, but not limited to, the receipt of all necessary regulatory and stock exchange approvals, including the approval of the TSX Venture Exchange.

The insider debt settlements are exempt from the valuation and minority shareholder approval requirements of Multilateral Instrument 61-101 ("MI 61-101") by virtue of the exemptions contained in sections 5.5(a) and 5.7(1)(a) of MI 61-101 in that the fair market value of the consideration for the securities of the Company to be issued to insiders does not exceed 25% of its market capitalization.

Tags:  Graphene  Gratomic 

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High-quality boron nitride grown at atmospheric pressure

Posted By Graphene Council, Wednesday, April 22, 2020
Graphene Flagship researchers at RWTH Aachen University, Germany and ONERA-CNRS, France, in collaboration with researchers at the Peter Grunberg Institute, Germany, the University of Versailles, France, and Kansas State University, US, have reported a significant step forward in growing monoisotopic hexagonal boron nitride at atmospheric pressure for the production of large and very high-quality crystals.

Hexagonal boron nitride (hBN) is the unsung hero of graphene-based devices. Much progress over the last decade was enabled by the realisation that 'sandwiching' graphene between two hBN crystals can significantly improve the quality and performance of the resulting devices. This finding paved the way to a series of exciting developments, including the discoveries of exotic effects such as magic-angle superconductivity and proof-of-concept demonstrations of sensors with unrivalled sensitivity.

Until now, the most widely used hBN crystals came from the National Institute of Material Science in Tsukuba, Japan. These crystals are grown using a process at high temperatures (over 1500°C) and extremely high pressures (over 40,000 times atmospheric pressure). "The pioneering contribution by the Japanase researchers Taniguchi and Watanabe to graphene research is invaluable", begins Christoph Stampfer from Graphene Flagship Partner RWTH Aachen University, Germany. "They provide hundreds of labs around the world with ultra-pure hBN at no charge. Without their contribution, a lot of what we are doing today would not be possible."

However, this hBN growth method comes with some limitations. Among them is the small crystal size, which is limited to a few 100 µm, and the complexity of the growth process. This is suitable for fundamental research, but beyond this, a method with better scalability is needed. Now Graphene Flagship researchers tested hBN crystals grown with a new methodology that works at atmospheric pressure, developed by a team of researchers led by James Edgar at Kansas State University, US. This new approach shows great promise for more demanding research and production.

"I was very excited when Edgar proposed that we test the quality of his hBN", says Stampfer. "His growth method could be suitable for large-scale production". The method for growing hBN at atmospheric pressure is indeed much simpler and cheaper than previous alternatives and allows for the isotopic concentration to be controlled.

"The hBN crystals we received were the largest I have ever seen, and they were all based either on isotopically pure boron-10 or boron-11" says Jens Sonntag, a graduate student at Graphene Flagship Partner RWTH Aachen University. Sonntag tested the quality of the flakes first using confocal Raman spectroscopy. In addition, Graphene Flagship partners in ONERA-CNRS, France, led by Annick Loiseau, carried out advanced luminescence measurements. Both measurements indicated high isotope purity and high crystal quality.

However, the strongest evidence for the high hBN qualitycame from transport measurements performed on devices containing graphene sandwiched between monoisotopic hBN. They showed equivalent performance to a state-of-the-art device based on hBN from Japan, with better performance in some areas.

"This is a clear indication of the extremely high quality of these hBN crystals," says Stampfer. "This is great news for the whole graphene community, because it shows that it is, in principle, possible to produce high quality hBN on a large scale, bringing us one step closer to real applications based on high-performance graphene electronics and optoelectronics. Furthermore, the possibility of controlling the isotopic concentration of the crystals opens the door to experiments that were not possible before."

Mar García-Hernández, Work Package Leader for Enabling Materials, adds: "Free-standing graphene, being the thinnest material known, exhibits a large surface area and, therefore, is extremely sensitive to its surrounding environment, which, in turn, results in substantial degradation of its exceptional properties. However, there is a clear strategy to avoid these deleterious effects: encapsulating graphene between two protective layers."

García-Hernández continues: "When graphene is encapsulated by hBN, it reveals its intrinsic properties. This makes hBN an essential material to integrate graphene into current technologies and demonstrates the importance of devising new scalable synthetic routes for large-scale hBN production. This work not only provides a new and simpler path to produce high-quality hBN crystals on a large scale, but it also enables the production of monoisotopic material, which further reduces the degradation of graphene when encapsulated by two layers."

Andrea C. Ferrari, Science and Technology Officer of the Graphene Flagship and Chair of its Management Panel, adds: "This is a nice example of collaboration between the EU and the US, which we fostered via numerous bilateral workshops. Devising alternative approaches to produce high-quality hBN crystals is crucial to enable us to exploit the ultimate properties of graphene in opto-electronics applications. Furthermore, this work will lead to significant progress in fundamental research."

Tags:  Andrea C. Ferrari  Christoph Stampfer  Graphene  Graphene Flagship  Hexagonal boron nitride  Mar García-Hernández  ONERA-CNRS  optoelectronics  RWTH Aachen University  Sensors 

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