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Engineering Edge States of Graphene Nanoribbons for Narrow-Band Photoluminescence

Posted By Graphene Council, Monday, May 11, 2020
A bottom-up approach for coupling graphene nanodots (GND) covalently at the edges of graphene nanoribbons (GNR) to create quantum-well-like states for well-defined narrow-band light emission.

Significance and Impact
This work establishes a new strategy to achieve narrow-band emission by engineering interface states of mixed-dimensional GNR-GND heterojunctions with atomic precision.

Research Details
– Covalent heterostructures are formed by fusing GNDs to the edges of GNRs via controlled on-surface reactions of molecular precursors.

– Scanning tunneling microscopy (STM) reveals the quantum-well-like electronic states and photoluminescence (PL) spectra show a defined optical transition energy with an ultra-narrow linewidth.

Tags:  Graphene  Graphene Nanoribbons  quantum materials 

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General Graphene Offers Tailored Approach to Producing Roll-to-Roll Single-Sheet Graphene

Posted By Dexter Johnson, The Graphene Council, Monday, May 11, 2020

Recognizing that the commercialization of graphene was an engineering problem rather than a science problem, General Graphene Corporation has developed the first large-scale, roll to roll CVD graphene production system.

General Graphene has been built upon a singular focus: producing a consistent graphene product at an industrial scale and a price that industry can afford.

Through this single-minded approach, General Graphene has developed the capability to deliver the cost/volume breakthrough for CVD graphene for which many industries have been waiting.

General Graphene recently joined The Graphene Council as a corporate member and we took that opportunity to talk to Kevin Weir, the director of business development at General Graphene, to find out a bit more about how they have engineered a solution to expanding the commercialization of graphene.

Q: Can you explain what your manufacturing method is for producing large-area graphene? Is it chemical vapor deposition (CVD) or some hybrid of CVD?

A: First, thank you for the opportunity to speak to the graphene community. We appreciate all that the Graphene Council does to promote graphene producers and our partners and appreciate the voice the Council brings to industry.  We are honored to be a member of this great club!

To answer your question, General Graphene Corporation is an advanced materials and manufacturing company, focused only on CVD graphene.  We are based in Knoxville, Tennessee, a stones’ throw from the Oak Ridge National Laboratory.  Our current focus is optimizing our roll-to-roll manufacturing process to produce large area, application-specific graphene sheets. We synthesize our graphene continuously on different metal catalyst substrates at atmospheric conditions with a high throughput rate.

The type of graphene we supply is mass-customized, which means that we adapt the graphene properties to meet the specific requirements of the intended application and customer requirements. We have no standard products, so to speak. It is our unique processing method that allows this optimized production and industrial scale.  Our customers understand this, and we work closely with them to design the optimum graphene for their needs.

Q: What are the origins of this production method?

A: Our capability is based on a concept originally developed at Oak Ridge National Laboratory by Dr. Ivan Vlassiouk.  Whilst we continue to build on the fundamental science, we focus a lot on the engineering and protecting our technology.  This has helped the company move CVD graphene manufacturing away from lab scale batch production towards true, low-cost, industrial-scale production.

Q: What kind of large-area graphene does it produce and how does it differ from competitive CVD graphene?

A: Our scientists can design recipes and adapt the graphene produced to meet the specific client and industry needs.  We can produce large sheets of graphene with a range of single to multiple layers, large crystal sizes and very high surface coverage.  With this we can tune conductivity, barrier properties and other desired performances.

Because our production equipment is highly programmable - in addition to making monolayer graphene, we also manufacture multilayer graphene’s and graphene foams, which offer additional desirable properties.  The ability to tailor solutions to market needs at high rate and low cost, opens new opportunities to industry.   We want to enable industry innovators to design their unique and differentiated products, with the confidence that they can receive high performance graphene in sufficient quantities and at an acceptable cost.

Q: What application areas are you targeting for your graphene? Do you see these application areas evolving and expanding, or do you expect greater application focus over time?

A: The ability to tune our graphene for specific industrial requirements opens up many markets. For example, we can produce multilayer graphene with incredible barrier properties as well as monolayer graphene with extremely large surface area, varying crystal sizes to minimize defects and greater than 98% substrate coverage. Among the development applications in which our graphene is currently being employed, are transparent conductors, a variety of electronic components and connectors, and Li-ion batteries. We are also investigating other energy production and storage applications and molecular filtration, bio engineering (e.g., stem cell growth and the production of special proteins), optical sensors and OLED’s.

Q: Where do you see yourself in the value chain, i.e. do you expect to remain a producer of large-area graphene, or do you expect to move up the value chain to making devices from the graphene you produce?

The objective of General Graphene is to offer commercially available volumes of customized, large area graphene in a roll-to-roll form at an affordable cost.

The products are supplied directly to the device or application OEM.  So we plan to remain upstream in the value chain.

With regards to application development, we partner directly with the systems provider or OEM. Together we develop performance and cost targets, design and manufacture the graphene production system and then support prototype development, testing and commercial validation.

Q: Bulk graphene remains the material that is being the most used in commercial applications, largely in composite applications. How do you foresee large-area graphene sheets gaining a larger commercial market, i.e. replacing bulk graphene in composite applications, or in entirely new application areas, such as electronics and other higher value devices?

The opportunity for CVD graphene is to grow its own industry niches. There are huge, latent market opportunities, ready to accept CVD graphene as soon as the product is available at large scale and at an affordable cost.

This large sheet, single and multilayer graphene competes with very few of the applications which demand bulk graphene powders.  Bulk graphene is the perfect format for mixing into resins, rubber and coatings, adding excellent conductive, wear resistance, durability, lubrication and strength performance to those systems. This graphene sector is doing an amazing job in identifying applications, proving the value of graphene and scaling their businesses.

With regards to our specific atmospheric CVD process, it is ideal for growing customized single and multilayer graphene sheets directly onto metal substrates and components at scale. This is critical in providing industrial volumes of usable sheet graphene at an acceptable cost. 

I would add that our single and multi-layer graphene sheets perform differently from bulk products. For example, our graphene acts as an extreme barrier at a couple of nm thickness, ideal for advanced molecular filtration applications. This same property is used to prevent corrosion or oxidation of sensitive substrates, increasing a components useful life. It is a super performing conductor for electronics, batteries and sensors. At the same time, it is highly transparent, making this form of graphene a great choice for transparent conductors and OLED’s.

It is clear that all types of graphene can have their optimum place in industry.  Our job as the graphene industry is to establish our niches, educate product developers and find exciting business models that will create significant value to customers.  Only then can we proliferate the application of this amazing technology.

Tags:  CVD graphene  General Graphene  Oak Ridge National Laboratory  Roll-to-Roll 

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Talga Resources: QUARTERLY ACTIVITIES REVIEW

Posted By Graphene Council, Saturday, May 9, 2020
Battery anode and graphene additives company Talga Resources Ltd (ASX:TLG)(“Talga” or “the Company”) is pleased to report its activities for the quarter ending 31 March 2020. The following content is as reported by TALGA. 

March 2020 quarter activities included:

COMMERCIAL & PRODUCT DEVELOPMENT

• MOU agreement signed with Mitsui for joint project development

• Successful 60 tonne pilot graphite concentrate program supports anode market development

• Talga in Bentley Motors electric drive project (subsequent to the period)

• 33,000 tonne ship trials push graphene-coating demand

MINERAL PROJECT DEVELOPMENT & EXPLORATION

• Environmental approval received for Vittangi Stage 1 Mining Operation, Sweden

CORPORATE & INVESTOR RELATIONS

• COVID-19 operational update and cost reduction measures

• Cash balance of A$6.6 million as at 31 March 2020

Managing Director, Mr Mark Thompson: “Amid the challenge of the COVID-19 outbreak, the Talga team achieved significant milestones this quarter, advancing our goal of becoming Europe’s next commercial scale Li-ion battery anode producer.

During this period we partnered with Mitsui, one of the largest global investment and trading companies, and gained approval of our Stage 1 mining permit in Sweden, while responding rapidly to the pandemic in line with government directives across all our countries of operation.

I am heartened by the positive way our team has adopted the measures we have had to take, and thank everyone involved in responding so well to the unfolding situation.”  COMMERCIAL AND PRODUCT DEVELOPMENT

Joint Anode Project Development MOU Agreement executed with Mitsui   Mitsui & Co. Europe Plc, the subsidiary of Mitsui & Co., Ltd., one of the largest global trading and investment companies based in Japan, and Talga executed a Memorandum of Understanding (“MoU”) during the quarter to evaluate joint development of the Vittangi Anode Project in northern Sweden. The MoU outlines the intention to negotiate and enter into definitive agreements to form a joint venture with respect to the financing, construction and operation of the Vittangi Anode Project, subject to a series of technical and commercial evaluation stages.

The execution of the MoU follows the completion of a Pre-Feasibility Study (ASX:TLG 23 May 2019) outlining the strong economics of the Vittangi Anode Project and a period of undertaken due diligence.

The potential joint development offers substantial synergies in establishing a European anode supply chain, securing a strategic source of anode products for Mitsui customers (ASX:TLG 20 March 2020) and growth in the battery materials business.

Completed 60 tonne pilot flotation program supports Talga anode development

A Talga pilot-scale processing program of 60 tonne Vittangi graphite ore, forming part of the Stage 1 DFS for the Vittangi Anode Project, was successfully completed during the period under review (ASX:TLG 30 January 2020).

The pilot processing program employed continuous test conditions for numerous key processing steps using advanced, industrial scale equipment at a Scandinavian toll milling and testing facility.

The program achieved the desired product targets using equipment up to 20x larger than that of previous programs. The successful scale-up demonstrates the suitability of the Pre-Feasibility Study process flowsheet for planned commercial production (ASX:TLG 23 May 2019).

The graphite concentrate produced has progressed to next stage refining into Talga’s flagship anode product (Talnode®-C) for on-going anode market development and customer qualification programs.

A lithium-ion battery ‘pouch’ cell with 100% Talnode®-C anode being tested at Talga’s lab in Cambridge, UK.

Copper windings of electric motors used in passenger vehicles

Talga engage in Bentley Motors e-axle development co-funded by Innovate UK

Subsequent to the quarter, Talga announced its participation in the Innovate UK co-funded “OCTOPUS” project, aiming to deliver the ultimate single unit e-axle solution designed specifically to meet Bentley Motors performance specifications (ASX:TLG 27 April 2020).

Under the project Talga will develop and provide graphene materials for the high performance electric motor windings to deliver an aluminium-based solution aimed at outperforming, and ultimately replacing, the copper windings currently used. For automotive manufacturers this could reduce vehicle weight and increase performance, safety and driving range while retaining sustainability and economics.

The improved motor windings form part of the project’s aim of developing next generation lightweight high performance component systems that integrate the latest advanced materials and manufacturing techniques. The components are to be tested at sub-system and system level for an integration route into future e-axle designs.

Lightweight and high performance automotive components complement Talga’s range of Li-ion battery anode products, and success in this program would open opportunities to replace copper wire in many large-scale applications globally.

Commercial-scale ship coating trials push demand for Talcoat® samples

In the previous quarter, Talga released details of a Talcoat® product, a graphene additive for maritime primer coatings, applied on two 33,000 tonne ocean going vessels at sea under large-scale trials (ASX:TLG 4 November 2019 and ASX:TLG 17 December 2019).

Subsequent to the publication of the trials additional parties across several sectors of the global coating industry have engaged with Talga and received Talcoat product samples. These are now undergoing testing by manufacturers and applicators, varying in size and jurisdiction, with positive initial test results.

Negotiations towards purchase agreements are underway with some parties and details will be released as and when any definitive commercial agreements are reached.

MINERAL PROJECT DEVELOPMENT AND EXPLORATION

Stage 1 Vittangi mining operation receives environmental approval

Environmental approval for Stage 1 mining operations at Talga’s 100% owned Vittangi Graphite Project in northern Sweden was received during the period under review (ASX:TLG 3 March 2020).

The trial mine environmental permit was issued by the Environmental Review Committee within the Norrbotten County Administration Board and is valid for three years.

The permit allows for the extraction of up to 25,000 tonnes of graphite ore for planned processing into concentrate and refining at Talga’s downstream anode refinery to produce Talnode®-C, the Company’s flagship Li-ion battery anode product developed to provide a sustainable and cost competitive choice for battery manufacturers.

The permitting process included comprehensive test work and studies to minimise the environmental footprint of the operation and upon conclusion of Stage 1 mining the site will be rehabilitated using the successful measures from the Company’s 2015-2016 trial mining campaign.

Preparations for site works and contractor selection is underway with operation planning to commence following completion of further statutory compliance, Stage 1 refinery permitting and financing activities.

Environmental and statutory permit applications for Stage 2 mining and concentration operations, with a processing capacity of 100,000 tonnes per annum of graphite ore, are nearly complete but now expected to be submitted in Q2 2020.

In full-scale production the graphite concentrate will feed Talga’s planned downstream refinery in the coastal city of Luleå, 250km to the south, to produce 19,000 tonnes per annum of Talnode-C as per the design parameters detailed in Talga’s May 2019 Pre-Feasibility Study (ASX:TLG 23 May 2019).

Tenement Interests

As required by ASX listing rule 5.3.3, refer to Appendix 1 for details of Talga’s interests in mining tenements held by the Company. No new joint ventures or farm-in/farm-out activity occurred during the quarter. Some non-core project tenements were rationalised or relinquished during the period under review.

CORPORATE AND INVESTOR RELATIONS

Share Registry Update

During the quarter Talga’s share registry changed to Automic Group. The change took effect from 20th January 2020 (ASX:TLG 20 January 2020).

Measures implemented to manage effect of COVID-19 on Talga operations

Subsequent to the period under review, the Company proactively implemented a range of measures to manage the effect of COVID-19 on its operations (ASX:TLG 2 April 2020). The policies and procedures put into effect focuses on the well-being of Talga’s people, partners and customers. Where possible, Talga staff across the UK, Germany, Sweden and Australia continue working remotely to deliver corporate, operational and product marketing functions.

Dealings with customers are ongoing and development of the Vittangi Anode Project is proceeding with minor interruptions. The Stage 1 DFS finalisation and Stage 2 permit application submission are now targeting Q2 2020.

Activities at Talga’s test facility in Rudolstadt continue, subject to government precautions and at a reduced rate, with priority placed on finalising samples and materials already in production. The Company’s current stocks of Talphite® and Talnode® products are considered sufficient to meet demand in the short term.

Talga’s participation across Innovate UK electric vehicle technology projects and customer graphene programs also continue subject to quarantine restrictions.

To maximise the Company’s capital position, Talga has implemented a group-wide cost reduction programme to reduce fixed and variable costs. As part of the cost reduction programme, the executive team, senior management and the board will undertake significant salary reductions, ranging 20% - 50%, for the remainder of the financial year.

Cash outflow during the period included some major but temporary costs relating to accelerated development of the Vittangi Anode Project in Sweden. These development activities, although ongoing to an extent, have largely been completed and the Company expects to have materially lower cash outflow going forward.

Financial

Talga closed out the 2020 March quarter with A$6.6 million cash-in-bank and was capitalised at ~A$76 million (based on closing price 29 April 2020). Currently the Company has 243.6 million quoted ordinary shares and 11.8 million unlisted options on issue.

This announcement has been authorised by the Board of Directors of Talga Resources Ltd. 

Tags:  Battery  Graphene  Graphite  Mark Thompson  Talga Resources 

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First Graphene and planarTECH Collaborate to Develop a Scaled Supply Chain for the Production of Graphene Face Masks

Posted By Graphene Council, Saturday, May 9, 2020
First Graphene Ltd, (“FGR” or “First Graphene “) the leading global producer of advanced graphene products and planarTECH (Holdings ) Ltd, (“ planarTECH”), a global leader in graphene process equipment and graphene-enabled products agree to collaborate on graphene enhanced personal protective equipment (PPE) products. 

First Graphene and planarTECH have signed a memorandum of understanding towards developing a robust supply chain for the manufacture of innovative graphene-enhanced personal protective equipment.

planarTECH have developed an innovative face mask which utilises a graphene coating to provide anti-static and bacteria-resistant properties to the mask.  Current demand for these products is high as world populations seek protection from airborne infection and planarTECH need to increase their manufacturing supply chain capability to meet growing market demand accordingly.  PureGRAPH® additives are already being used in the mask application and First Graphene have the capability to supply the volumes required for this rapidly growing business.

The face mask will be manufactured by planarTECH under their 2AM brand.  Washable and reusable, the mask is also resistant to bacteria and repels airborne particles.  The new 2AM face mask has the potential to become an essential, everyday accessory during these uncertain times.

The two companies have agreed to collaborate to rapidly test and implement the use of PureGRAPH® materials into existing and new anti-static coatings for PPE.  Materials development activities are already underway, and the companies anticipate quick progress to full-scale manufacturing of the face mask.  With the anti-static coating capable of repelling airborne particles and offering bacteria-resistant properties further graphene enabled products in the PPE sector are expected to emerge.

Craig McGuckin, Managing Director for First Graphene Ltd., said, “We have been very impressed by the speed to commercialisation that planarTECH have achieved with the graphene face masks and we are pleased to support the growth of this opportunity”.

Ray Gibbs, Chairman for planarTECH (Holdings) Ltd., said, “For successful growth of our business, planarTECH is seeking a graphene supply partner that can reliably deliver high quality consistent products.  We are very aware of First Graphene’s robust supply capability delivered globally from its Australian facility. Following on from significant trials utilising PureGRAPH® materials and we are excited about this collaboration to meet the rapid growth in demand for face masks and other PPE products.”

Tags:  Craig McGuckin  First Graphene  Graphene  Healthcare  planarTECH  Ray Gibbs 

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Second skin protects against chem, bio agents

Posted By Graphene Council, Saturday, May 9, 2020
Recent events such as the COVID-19 pandemic and the use of chemical weapons in the Syria conflict have provided a stark reminder of the plethora of chemical and biological threats that soldiers, medical personnel and first responders face during routine and emergency operations.

Personnel safety relies on protective equipment which, unfortunately, still leaves much to be desired. For example, high breathability (i.e., the transfer of water vapor from the wearer’s body to the outside world) is critical in protective military uniforms to prevent heat-stress and exhaustion when soldiers are engaged in missions in contaminated environments. The same materials (adsorbents or barrier layers) that provide protection in current garments also detrimentally inhibit breathability.

To tackle these challenges, a multi-institutional team of researchers led by Lawrence Livermore National Laboratory (LLNL) scientist Francesco Fornasiero has developed a smart, breathable fabric designed to protect the wearer against biological and chemical warfare agents. Material of this type could be used in clinical and medical settings as well. The work was recently published online in Advanced Functional Materials and represents the successful completion of Phase I of the project, which is funded by the Defense Threat Reduction Agency through the Dynamic Multifunctional Materials for a Second Skin "D[MS]2" program. 

"We demonstrated a smart material that is both breathable and protective by successfully combining two key elements: a base membrane layer comprising trillions of aligned carbon nanotube pores and a threat-responsive polymer layer grafted onto the membrane surface," Fornasiero said.

These carbon nanotubes (graphitic cylinders with diameters more than 5,000 times smaller than a human hair) could easily transport water molecules through their interiors while also blocking all biological threats, which cannot fit through the tiny pores. This key finding was previously published in Advanced Materials.

The team has shown that the moisture vapor transport rate through carbon nanotubes increases with decreasing tube diameter and, for the smallest pore sizes considered in the study, is so fast that it approaches what one would measure in the bulk gas phase. This trend is surprising and implies that single‐walled carbon nanotubes (SWCNTs) as moisture conductive pores overcome a limiting breathability/protection trade-off displayed by conventional porous materials, according to Fornasiero. Thus, size-sieving selectivity and water-vapor permeability can be simultaneously enhanced by decreasing SWCNT diameters.

Contrary to biological agents, chemical threats are smaller and can fit through the nanotube pores. To add protection against chemical hazards, a layer of polymer chains is grown on the material surface, which reversibly collapses in contact with the threat, thus temporarily blocking the pores.

"This dynamic layer allows the material to be ‘smart’ in that it provides protection only when and where it is needed," said Timothy Swager, a collaborator at the Massachusetts Institute of Technology who developed the responsive polymer. These polymers were designed to transition from an extended to a collapsed state in contact with organophosphate threats, such as sarin. "We confirmed that both simulants and live agents trigger the desired volume change," Swager added.

The team showed that the responsive membranes have enough breathability in their open-pore state to meet the sponsor requirements. In the closed state, the threat permeation through the material is dramatically reduced by two orders of magnitude. The demonstrated breathability and smart protection properties of this material are expected to translate in a significantly improved thermal comfort for the user and enable to greatly extend the wear time of protective gears, whether in a hospital or battlefield. 

"The safety of warfighters, medical personnel and first responders during prolonged operations in hazardous environments relies on personal protective equipment that not only protects but also can breathe," said Kendra McCoy, the DTRA program manager overseeing the project. "DTRA Second Skin program is designed to address this need by supporting the development of new materials that adapt autonomously to the environment and maximize both comfort and protection for many hours."

In the next phase of the project, the team will aim to incorporate on-demand protection against additional chemical threats and make the material stretchable for a better body fit, thus more closely mimicking the human skin.

LLNL researchers Chiatai Chen, Eric Meshot, Steven Buchsbaum, Ngoc Bui, Melinda Jue, Sei Jin Park, Carlos Valdez, Saphon Hok and Kuang Jen Wu also contributed to this work, as well as collaborators at Massachusetts Institute of Technology (Yifan Li, Myles Herbert, Rong Zhu, Oleg Kulikov, Ben McDonald, Qilin He) and the U.S. Army Combat Capabilities Development Command - Soldier Center (Christopher Doona).

Tags:  Advanced Functional Materials  Defense Threat Reduction Agency  Francesco Fornasiero  Graphene  Lawrence Livermore National Laboratory  Massachusetts Institute of Technology  Timothy Swager 

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LG Electronics Secures Its Position in CVD Graphene Production

Posted By Dexter Johnson, The Graphene Council, Thursday, May 7, 2020

When LG Electronics makes it known that it is serious about producing high-quality CVD graphene, the electronics community stops and listens.

LG Electronics has been producing CVD graphene for almost a decade, but last year they made it known in the press that they were making a serious commercial venture with their CVD graphene technology.

Recently, LG Technology Center Europe joined The Graphene Council as a Corporate Member and we took that occasion as an opportunity to interview the Chief Technology Office at LG Electronics, Youn-Su Kim, Ph.D, to ask him about how LG is approaching their graphene production and what we can expect from them in this space going forward. Here is our interview.

Q: When did LG Electronics become a CVD graphene producer?

A: We started R&D of graphene in 2012 and have developed our own roll-to-roll (R2R) CVD graphene technology for large-area and high-quality graphene production.

In 2019, we were able to produce high-quality CVD graphene with a rigorous quality control and announced LG’s CVD graphene technology.

Q. What was behind that decision, i.e. were you trying to meet some internal demand, or did you see an unmet need in the marketplace?

A: We mainly focused on ensuring high-quality and reproducibility of our graphene products with a rigorous quality control. Our products have been known with the world-best data in terms of electron mobility, sheet resistance and uniformity. Now, we expect to accelerate the development of CVD graphene applications in collaboration with external institutes.

First, we have realized that the quality of CVD graphene in the marketplace still needs to be improved. This is why we have been developing our high quality CVD graphene technology. Secondly, developing graphene applications is still in process and we haven’t seen CVD graphene based products in the marketplace yet.

Q. It has been announced that LG will be producing roll-to-roll (R2R) CVD graphene. Does that mean your production will be exclusively R2R, or will you produce other forms of CVD graphene?

A: Yes, we have developed our own graphene technology from our home-made R2R  CVD reactors. We have a capability for high speed and large-area production with Cu foil substrates.

We are available to produce CVD graphene with controlled grain size (5~ 500 um2) on Cu foil or Si wafer substrates.

Q. What forms are you making and marketing the CVD graphene, i.e. in wafer sizes? In those forms what is your production capacity?

A: We are available to produce monolayer CVD graphene on Cu foil (up to tens of meter rolls with 400 mm width) or 4~ 6” Si wafer substrates. With production rate of 60 m/hr, we can produce CVD graphene of 28,800 m2/year. In addition, larger-area CVD graphene production is possible due to our capability to design larger-area R2R CVD reactors from our institute for equipment development and production.

Q. It has been reported that LG has targeted its CVD graphene for biosensors, high-speed RF devices and display platforms. Are these reports correct and are there other applications LG is targeting for its CVD graphene and among these what is the main application focus currently?

A: We haven’t yet decided the area of graphene applications to be developed. We are considering two things: One is the graphene application relevant to LG’s products, so that it facilitates entering the marketplace. The other is the graphene application that enables LG to extend its operations for a new business.

Whatever the graphene applications are, we expect them to make expansion of the global graphene market.

Q. What remains the biggest commercial challenge for CVD graphene? Is it an engineering issue, or is that the potential buyers are slow to adopt a new material? How can CVD graphene producers overcome these challenges?

A: We are facing both of them as big commercial challenges for CVD graphene.

For the engineering issue, the current CVD graphene technology needs to be further improved for the quality control.

As for the business issue, most of the companies that purchase a large amount of CVD graphene adhere to the suppliers of the existing CVD graphene instead of shifting to the upgraded one. Also, many potential buyers that develop device applications are not accustomed to use of CVD graphene for their applications. It may take some time for the potential buyers to adopt the CVD graphene.

To overcome the issues, we have to continuously promote low-cost and high-quality products and develop our own graphene application for progressively entering the graphene marketplace.

Q. Bulk graphene appears largely targeted for composite applications and CVD graphene for electronic applications. Is this a fair breakdown of the marketplace and how will these delineations evolve over time?

It is not about fair or unfair matters. The types of applications basically determine the types of graphene that are tot be used. We are more interested in achieving high performance of graphene in a given application that what type of graphene is being used. We will determine the types of graphene to use for different applications over time.

Tags:  CVD graphene  LG Electronics  LG Technology Center Europe  Youn-Su Kim 

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“MXenes” Hold Key Role in the Commercial Development of 2D Materials

Posted By Dexter Johnson, The Graphene Council, Thursday, May 7, 2020

In 2010, Researchers at Drexel University developed a 2D material that in comparison to other 2D materials, like graphene, received little fanfare.

Michel W. Barsoum and Yury Gogotsi at Drexel University’s A.J. Drexel Nanomaterials Institute, dubbed the material a “MXene” because of its origin from the process of etching and exfoliating atomically thin layers of aluminum from layered carbides called “MAX phases.” The M is for transition metal, the A for "A group" metal, and the X for carbon and/or nitrogen.

In the decade since that discovery the properties and range of applications for the material have multiplied, making it a key feature in the 2D material landscape.

The A.J. Drexel Materials Institute recently became an institutional member of The Graphene Council so we took that opportunity to ask Yury Gogotsi, Director of the Drexel Nanomaterials Institute some questions about MXene’s and how they are changing the landscape for 2D materials going forward.

Q: First off, can you tell us a little bit about MXenes? I understand the term “MXene” itself is based on its origin from the process of etching and exfoliating atomically thin layers of aluminum from layered carbides called “MAX phases.” [The M is for transition metal, the A for "A group" metal, and the X for carbon and/or nitrogen.] Is that correct? What else should we know about these materials?

A: MXenes (pronounced “maxenes”) are carbides and nitrides of transition metals, a fast-growing and already very large family of 2D materials. In a 2D flake of MXene, n + 1 (n = 1−4) layers of early transition metals (M) are interleaved with n layers of carbon or nitrogen (X, elements in gray in Figure 1), with a general formula of Mn+1XnTx. The Tx in the formula represents the surface terminations, such as O, OH, F, and/or Cl, which are bonded to the outer M layers.  MXenes are currently produced by selective chemical etching of aluminum silicon, gallium or aluminum carbide layers form layered ceramics such as MAX phases and related structures.  The key features of the archetypical MXenes, such as Ti3C2Tx, include their high metallic conductivity, hydrophilicity and high negative surface charge that allows dispersion in water, forming stable colloidal solutions of single-layer flakes or liquid crystal slurries with rheological behavior of clay with no surfactants or additives. So, they combine the best properties of graphene oxide (GO) and reduced graphene oxide (rGO) and take those to extreme (like 5-10 times higher conductivity compared to rGO films). And since there are so many MXene structures and compositions, their optical, catalytic, electrochemical and other properties can be tuned in a very wide range.

Q: It appears that you first isolated these MXenes in 2010. Within the first few years of your research with these materials, you had already isolated nine different forms of them. How many forms of MXenes have you created at this point? How does each of these forms differ, i.e. range of different properties, range of different potential applications, different synthesis methods, etc.?

A: The first MXene, Ti3C2, was synthesized by Michel Naguib, a PhD student advised by Prof. Michel Barsoum and myself, in 2010 and published on 2011. There are at least 30 stoichiometric MXenes reported so far (from more than 100 predicted) and a dozen of solid solutions. Most of them were first synthesized at Drexel University, but discoveries are being made around the world, in particular Chinese and Swedish researchers contributed significantly to making new MXene structures. Since solid solutions are possible on both, X site (carbonitrides) and M site, an infinite number of compositions can be made. This is very important as one can tune finely properties by “alloying” a particular MXene, just as it’s done with metal alloys.  Also, different synthesis methods lead to different surface terminations, which allow further control over the properties. I also expect many other related 2D structures that are different from MXene stoichiometries to be discovered (2D borides, dicarbides, layered carbide/nitride structures, oxycarbides, oxynitrides, etc.).

 

There are large and very distinct differences in their properties – several orders of magnitude differences in conductivity of MXene films, plasmon resonance across the entire visible and far into infrared range, very different chemical properties determined by the chemistry of specific transition metal in the surface layer. MXenes have a large variety of colors covering the entire visible spectrum offering a potential for many optoelectronic, plasmonic and photonic applications. Very efficient light-to-heat conversion has already attracted attention in photodynamic cancer therapy. Chemically tunable in a very wide range work functions is very valuable for solar cells, light emitting diodes and other optoelectronic devices. Some MXenes have a wide range of electrochemical stability (good for use in supercapacitor electrodes) and some other split water under very low overpotential (good for electrocatalytic water splitting). This is the beauty of having a compositional and structural variety.

Q: An early application for MXenes was thought to be in energy storage. How has that application developed over time? Are there commercial uses of the material for these applications? What other applications are demonstrating potential and has there been interest in developing them commercially?

A: The use of MXenes in batteries was the first application explored because our initial work and the discovery of MXenes at Drexel was funded by the US Department of Energy.  A major company has acquired an exclusive license for the use of MXenes in supercapacitors. Bothe applications are very promising and MXenes offer advantages of conductivity exceeding all other electrochemical energy storage materials  (high rate/high power advantage)  and redox reactions of transition metals. However, those are challenging applications requiring very large volume of material and large-scale commercial production of energy storage devices will probably become economically justified a few years down the road. I expect the initial growth to be driven by smaller-volume applications in conductive films, inks, optoelectronics and medicine, which will increase the availability of the material and push the price down. This will allow applications in energy storage and composites to follow.

Q: MXenes belong to a fairly rich and expanding landscape of 2D materials. What role do you see MXenes playing in this 2D landscape, i.e. a complimentary material with other 2D materials or the basis for new devices on its own?

A: MXenes can perform extremely well in many applications. The key advantage explored so far is their high metallic electronic conductivity, also in transparent films. They are the best available materials for electromagnetic interference shielding or printable 5G and other antennas. However, their metallic conductivity can be combined with semiconducting properties of transition metal dichalcogenides, dielectric properties of boron nitride or oxidation resistance of rGO.  MXenes can act as active materials (electrodes in batteries and supercapacitors or gas sensors) but also as current collectors, interconnect or catalyst supports.

Q: Along the lines of the last question, how do you see the world of graphene and 2D materials working out? Currently, graphene has some real commercial markets, primarily in composites. However, other 2D materials seem to have more limited commercial use. Are these 2D materials still looking to take a foothold in electronics applications, or can they compete with graphene in non-electronics applications?

A: Graphene has found large-volume applications in composites largely because strong and conductive multilayer sheets can be produced in quantities by mechanical shearing of natural graphite. Additives to paint for corrosion protection, conductive additives, heat spreaders for cell phones, etc., are among applications where graphene derivatives outperform other materials. In my opinion, industrial applications of graphene will continue expanding. The hype will be over after a few years and applications in composites, sorbents, protective coating, and conductive additives will keep growing in volume. In many of those applications, graphene-based products will replace carbon black, nanotubes or clay in polymer-matrix composites, but unique applications in flexible and wearable devices, as well as printable electronics are expect to emerge. GO and rGO membranes look promising for many separation applications. It will be interesting to see if applications of  single-layer CVD graphene will make a difference in technology one day.  It’s still not obvious to me, but hope this is going to happen.

TMDs are being widely researched, but except electronic applications, which may still be very far away, there are always other materials that can outperform them in practice (graphene is stronger and cheaper, oxides are more stable, Ti3C2 is more conductive, Mo2C is a better HER catalyst, etc.). No other 2D material is expected to have the same low price as multilayer graphene simply because there are no equally abundant and inexpensive natural precursors for other 2D materials and more expensive synthesis processes are often involved. However, in application in computer electronics, cell phones, sensors or wearable electronics, internet of things devices, the weight of the material used is negligible, so the performance and manufacturability become the key factors. This is where TMDs and other 2D materials may find a foothold. We need to find out which materials can perform better in a particular application, making the devices smaller and adding new functions, and can be manufactured into the desired components. Processing of MXenes from aqueous colloidal solution without any additives or surfactants is a huge plus – you can print, spray- or spin-coat safely, and no burning of the binder/surfactant if needed. Making ink-jet printed patterns with conductivity ten times that of printed graphene and not requiring heat treatment opens many opportunities.

I also look at 2D materials as convenient building blocks. They are like bricks that can be laid in the required order and this can be done by simple solution processing, e.g., spray coating. For example, printable batteries and supercapacitors when layers or 2D materials forming (1) current collector, (2)anode, (3) separator, (4) cathode, (5) current collector, (6) sealant are sprayed sequentially. This is one of the reasons industry will use a variety of 2D materials when building devices in the future.

Q: As an academic, what remains an issue of miscommunication between the research and business communities as it relates to 2D materials? How can this issue (or issues) be overcome?

A: Academics should not oversell new materials that they discovered just because they are so excited about their babies (I feel the same way about MXenes, nanodiamond or carbide-derived carbons that I’ve been exploring), they need to understand where the use of their materials is practical and justified. Yes, it’s hard to expect a researcher like myself to say that while MXene can do a better job than graphene in a certain adsorption application, the company should still go with multilayer graphene or even clay because of a much lower cost. This is the decision for the business to make. On the other hand, the business community and especially investors, should not go after hype (yesterday-  nanotubes, today - graphene, or tomorrow - MXene), but after useful properties that enable applications.  We also need more dialogue between business and research communities, where inventors of new materials can talk to potential users of those materials and figure out what properties are really needed. 

There are clear technological advantages that 2D materials offer. If a micron-thin titanium carbide MXene film processed from water solution can replace a 15-30 micron copper or aluminum foil as a current collector, interconnect, antenna or electromagnetic interference shielding, there is a very obvious technological advantage that can be used in any devices where size and weight reduction is of importance.  When the same MXene film replaces a gold or platinum metal electrode in medical technology, there is not only performance, but also a significant price advantage as well. Those are the applications industry should go after.

Tags:  2D materials  Drexel University  MXenes  transition metals  Yury Gogotsi 

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First Graphene Ltd and Hexcyl to Collaborate on HDPE Project

Posted By Graphene Council, Thursday, May 7, 2020
First Graphene Limited is pleased to advise that Hexcyl is collaborating with the Company to develop PureGRAPH® enhanced HDPE materials for use in Hexcyl’s range of oyster baskets and long-line farming systems.

High-density polyethylene (HDPE) is a thermoplastic polymer produced from the monomer ethylene. With a high strength-to-density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes and plastic timbers.

The incorporation of high-performing PureGRAPH® additives will seek to improve the mechanical properties of the HDPE, while at the same time provide greater longevity of the systems in high energy farming environments.

Hexcyl Systems offer oyster farmers and shellfish farmers a wide range of shellfish aquaculture products designed for Adjustable Longline Shellfish Farming and other tidal systems. The products are manufactured in Australia and sold globally.

PureGRAPH® additives will be supplied to Hexcyl’s masterbatch and injection moulding companies over the next two weeks.

Craig McGuckin, Managing Director for First Graphene Ltd., said, “Working with Hexcyl Systems with their requirement for additional mechanical improvement is yet another industry where PureGRAPH® may provide benefits to material enhancement”.

Tags:  Craig McGuckin  First Graphene  Graphene  Hexcyl Systems  Polymer 

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Eavesdropping on single molecules with light by replaying the chatter

Posted By Graphene Council, Wednesday, May 6, 2020
The structure of individual molecules and their properties, such as chirality, are difficult to monitor in real time. It turns out that by temporarily bridging molecules together we can provide a lens into their dynamics.

A study led by Prof. Frank Vollmer at the University of Exeter’s Living Systems Institute has exposed new pathways for investigating biochemical reactions at the nanoscale. Thiol/disulfide exchange at equilibrium has not yet been fully scrutinised at the single-molecule level, in part because this cannot be optically resolved in bulk samples.

Light can, however, circulate around micron-sized glass spheres to form resonances. The trapped light can then repeatedly interact with its surrounding environment. By attaching gold nanoparticles to the sphere, light is enhanced and spatially confined down to the size of viruses and amino acids.

The resulting optoplasmonic coupling allows for the detection of biomolecules that approach the nanoparticles while they attach to the gold, detach, and interact in a variety of ways.

Despite the sensitivity of this technique, there is lacking specificity. Molecules as simple as atomic ions can be detected and certain dynamics can be discerned, yet we cannot necessarily discriminate them.

The breakthroughs reported in Nature Communications ("Optoplasmonic characterisation of reversible disulfide interactions at single thiol sites in the attomolar regime") have proceeded to amend this.

Reaction pathways regulated by disulfide bonds can constrain interactions to single thiol sensing sites on the nanoparticles. The high fidelity of this approach establishes precise probing of the characteristics of molecules undergoing the reaction.

By placing linkers on the gold surface, interactions with thiolated species are isolated for based on their charge and the cycling itself.

Sensor signals have clear patterns related to whether reducing agent is present. If it is, the signal oscillates in a controlled way, while if it is not, the oscillations become stochastic. For each reaction the monomer or dimer state of the leaving group can be resolved.

Surprisingly, the optoplasmonic resonance shifts in frequency and/or changes in linewidth when single molecules interact with it. In many cases this result suggests a plasmon-vibrational coupling that could help identify individual molecules, finally achieving characterisation.

"This excellent work by my PhD student, Serge Vincent, paves the way for many future single-molecule analysis techniques that we have only been dreaming about," Professor Frank Vollmer adds. "It is a crucial step for our project ULTRACHIRAL. ULTRACHIRAL seeks to develop breakthroughs in how we use light to analyse chiral molecules."

Tags:  Frank Vollmer  Graphene  nanoparticles  Sensors  University of Exeter 

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Supercapacitor promises storage, high power and fast charging

Posted By Graphene Council, Wednesday, May 6, 2020
A new supercapacitor based on manganese oxide could combine the storage capacity of batteries with the high power and fast charging of other supercapacitors, according to researchers at Penn State and two universities in China.

“Manganese oxide is definitely a promising material,” said Huanyu "Larry" Cheng, assistant professor of engineering science and mechanics and faculty member in the Materials Research Institute, Penn State. “By combining with cobalt manganese oxide, it forms a heterostructure in which we are able to tune the interfacial properties.”

The group started with simulations to see how manganese oxide’s properties change when coupled with other materials. When they coupled it to a semiconductor, they found it made a conductive interface with a low resistance to electron and ion transport. This will be important because otherwise the material would be slow to charge.

“Exploring manganese oxide with cobalt manganese oxide as a positive electrode and a form of graphene oxide as a negative electrode yields an asymmetric supercapacitor with high energy density, remarkable power density and excellent cycling stability,” according to Cheng Zhang, who was a visiting scholar in Cheng’s group and is the lead author on a paper published recently in Electrochimica Acta.

The group has compared their supercapacitor to others and theirs has much higher energy density and power. They believe that by scaling up the lateral dimensions and thickness, their material has the potential to be used in electric vehicles. So far, they have not tried to scale it up. Instead, their next step will be to tune the interface where the semiconducting and conducting layers meet for even better performance. They want to add the supercapacitor to already developed flexible, wearable electronics and sensors as an energy supply for those devices or directly as self-powered sensors.

Cheng Zhang is now an assistant professor at Minjiang University, China. The second Chinese university is Guizhou Education University. The paper is “Efficient Coupling of Semiconductors into Metallic MnO2@CoMn2O4 Heterostructured Electrode with Boosted Charge Transfer for High-performance Supercapacitors.”

Tags:  Cheng Zhang  Graphene  graphene oxide  Huanyu Larry Cheng  Minjiang University  Penn State  Supercapacitor 

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