Print Page | Contact Us | Report Abuse | Sign In | Register
Graphene Updates
Blog Home All Blogs
The latest news and information on all aspects of graphene research, development, application and commercialization.

 

Search all posts for:   

 

Top tags: graphene  2D materials  Sensors  Batteries  nanomaterials  University of Manchester  CVD  First Graphene  electronics  Li-ion batteries  coatings  graphene oxide  graphene production  The Graphene Flagship  Applied Graphene Materials  Carbon Nanotubes  composites  Energy Storage  Graphite  Haydale  Graphene Flagship  Healthcare  3D Printing  Battery  optoelectronics  polymers  Versarien  Adrian Potts  Andre Geim  biosensors 

Coating for metals rapidly heals over scratches and scrapes to prevent corrosion

Posted By Graphene Council, The Graphene Council, Wednesday, February 6, 2019
Updated: Wednesday, February 6, 2019
It’s hard to believe that a tiny crack could take down a gigantic metal structure. But sometimes bridges collapse, pipelines rupture and fuselages detach from airplanes due to hard-to-detect corrosion in tiny cracks, scratches and dents.

A Northwestern University team has developed a new coating strategy for metal that self-heals within seconds when scratched, scraped or cracked. The novel material could prevent these tiny defects from turning into localized corrosion, which can cause major structures to fail.

“Localized corrosion is extremely dangerous,” said Jiaxing Huang, who led the research. “It is hard to prevent, hard to predict and hard to detect, but it can lead to catastrophic failure.” 

When damaged by scratches and cracks, Huang’s patent-pending system readily flows and reconnects to rapidly heal right before the eyes. The researchers demonstrated that the material can heal repeatedly — even after scratching the exact same spot nearly 200 times in a row.

The study was published today (Jan. 28) in Research, the first Science Partner Journal recently launched by the American Association for the Advancement of Science (AAAS) in collaboration with the China Association for Science and Technology (CAST). Huang is a professor of materials science and engineering in Northwestern’s McCormick School of Engineering.

While a few self-healing coatings already exist, those systems typically work for nanometer- to micron-sized damages. To develop a coating that can heal larger scratches in the millimeter-scale, Huang and his team looked to fluid. 

“When a boat cuts through water, the water goes right back together,” Huang said. “The ‘cut’ quickly heals because water flows readily. We were inspired to realize that fluids, such as oils, are the ultimate self-healing system.”

But common oils flows too readily, Huang noted. So he and his team needed to develop a system with contradicting properties: fluidic enough to flow automatically but not so fluidic that it drips off the metal’s surface. 

The team met the challenge by creating a network of lightweight particles — in this case graphene capsules — to thicken the oil. The network fixes the oil coating, keeping it from dripping. But when the network is damaged by a crack or scratch, it releases the oil to flow readily and reconnect. Huang said the material can be made with any hollow, lightweight particle — not just graphene.

“The particles essentially immobilize the oil film,” Huang said. “So it stays in place.”

The coating not only sticks, but it sticks well — even underwater and in harsh chemical environments, such as acid baths. Huang imagines that it could be painted onto bridges and boats that are naturally submerged underwater as well as metal structures near leaked or spilled highly corrosive fluids. The coating can also withstand strong turbulence and stick to sharp corners without budging. When brushed onto a surface from underwater, the coating goes on evenly without trapping tiny bubbles of air or moisture that often lead to pin holes and corrosion. 

“Self-healing microcapsule-thickened oil barrier coatings” was supported by the Office of Naval Research (ONR N000141612838). Graduate student Alane Lim and Chenlong Cui, a former member of Huang’s research group, served as the paper’s co-first authors.

Tags:  Graphene  Jiaxing Huang  Northwestern University 

Share |
PermalinkComments (0)
 

Large, stable pieces of graphene produced with unique edge pattern

Posted By Graphene Council, The Graphene Council, Wednesday, February 6, 2019
Updated: Wednesday, February 6, 2019

Graphene is a promising material for use in nanoelectronics. Its electronic properties depend greatly, however, on how the edges of the carbon layer are formed. Zigzag patterns are particularly interesting in this respect, but until now it has been virtually impossible to create edges with a pattern like this. Chemists and physicists at FAU have now succeeded in producing stable nanographene with a zigzag edge.

Not only that, the method they used was even comparatively simple. Their research, conducted within the framework of collaborative research centre 953  – Synthetic Carbon Allotropes funded by the German Research Foundation (DFG), has now been published in the journal Nature Communications*.

Bay, fjord, cove, armchair and zigzag – when chemists use terms such as these, it is clear that they are referring to nanographene. More specifically, the shape taken by the edges of nanographene, i.e. small fragments of graphene. Graphene consists of a single-layered carbon structure, where each carbon atom is surrounded by three others. This creates a pattern reminiscent of a honeycomb, with atoms in each of the corners. Nanographene is a promising candidate for use in the field of microelectronics, taking over from silicon which is used today and bringing microelectronics down to the nano scale.

The electronic properties of the material depend greatly on its shape, size and above all, periphery, in other words how the edges are structured. A zigzag periphery is particularly suitable, as in this case the electrons, which act as charge carriers, are more mobile than in other edge structures. This means that using pieces of zigzag-shaped graphene in nanoelectronic components may allow higher frequencies for switches.

The problem currently faced by materials scientists who want to research only zigzag nanographene is that this form makes the compounds rather unstable, and unable to be produced in a controlled manner. This is a prerequisite, however, if the electronic properties are to be investigated in detail.

The team of researchers led by PD Dr. Konstantin Amsharov from the Chair of Organic Chemistry II have now succeeded in doing just that. Not only have they discovered a straightforward method for synthesising zigzag nanographene, their procedure delivers a yield of close to one hundred percent and is suitable for large scale production. They have already produced a technically relevant quantity in the laboratory.

First of all, the FAU researchers produce preliminary molecules, which they then fitt together in a honeycomb formation over several cycles, in a process known as cyclisation. In the end, graphene fragments are produced from staggered rows of honeycombs or four-limbed stars surrounding a central point of four graphene honeycombs, with the sought-after zigzag pattern to their edges. Why is this method able to produce stable zigzag nanographene? The explanation lies in the fact that the product crystallises directly even during synthesis. In their solid state, the molecules are not in contact with oxygen. In solution, however, oxidation causes the structures to disintegrate quickly.

This approach allows scientists to produce large pieces of graphene, whilst maintaining control over their shape and periphery. This breakthrough in graphene research means that scientists should soon be able to produce and research a variety of interesting nanographene structures, a crucial step towards finally being able to use the material in nanoelectronic components.

Tags:  Friedrich–Alexander University  Graphene  Konstantin Amsharov  nanoelectronics  nanographene 

Share |
PermalinkComments (0)
 

Engineers develop novel strategy for designing semiconductor nanoparticles for wide-ranging applications

Posted By Graphene Council, The Graphene Council, Tuesday, February 5, 2019
Updated: Tuesday, February 5, 2019
Two-dimensional (2D) transition metal dichalcogenides (TMDs) nanomaterials such as molybdenite (MoS2), which possess a similar structure as graphene, have been donned the materials of the future for their wide range of potential applications in biomedicine, sensors, catalysts, photodetectors and energy storage devices.

The smaller counterpart of 2D TMDs, also known as TMD quantum dots (QDs) further accentuate the optical and electronic properties of TMDs, and are highly exploitable for catalytic and biomedical applications. However, TMD QDs is hardly used in applications as the synthesis of TMD QDs remains challenging.

Now, engineers from the National University of Singapore (NUS) have developed a cost-effective and scalable strategy to synthesise TMD QDs. The new strategy also allows the properties of TMD QDs to be engineered specifically for different applications, thereby making a leap forward in helping to realise the potential of TMD QDs.

Bottom-up strategy to synthesise TMD QDs

Current synthesis of TMD nanomaterials rely on a top-down approach where TMD mineral ores are collected and broken down from millimetre to nanometre scale via physical or chemical means. This method, while effective in synthesising TMD nanomaterials with precision, is low in scalability and costly as separating the fragments of nanomaterials by size requires multiple purification processes. Using the same method to produce TMD QDs of a consistent size is also extremely difficult due to their minute size.

To overcome this challenge, a team of engineers from the Department of Chemical and Biomolecular Engineering at NUS Faculty of Engineering developed a novel bottom-up synthesis strategy that can consistently construct TMD QDs of a specific size, a cheaper and more scalable method than the conventional top-down approach. The TMD QDs are synthesised by reacting transition metal oxides or chlorides with chalogen precursors under mild aqueous and room temperature conditions. Using the bottom-up approach, the team successfully synthesised a small library of seven TMD QDs and were able to alter their electronic and optical properties accordingly.

Associate Professor David Leong from the Department of Chemical and Biomolecular Engineering at NUS Faculty of Engineering led the development of this new synthesis method. He explained, “Using the bottom-up approach to synthesise TMD QDs is like constructing a building from scratch using concrete, steel and glass component; it gives us full control over the design and features of the building. Similarly, this bottom-up approach allows us to vary the ratio of transition metal ions and chalcogen ions in the reaction to synthesise the TMD QDs with the properties we desire. In addition, through our bottom-up approach, we are able to synthesise new TMD QDs that are not found naturally. They may have new properties that can lead to newer applications.”

Applying TMD QDs in cancer therapy and beyond

The team of NUS engineers then synthesised MoS2 QDs to demonstrate proof-of-concept biomedical applications. Through their experiments, the team showed that the defect properties of MoS2 QDs can be engineered with precision using the bottom-up approach to generate varying levels of oxidative stress, and can therefore be used for photodynamic therapy, an emerging cancer therapy.

“Photodynamic therapy currently utilises photosensitive organic compounds that produce oxidative stress to kill cancer cells. These organic compounds can remain in the body for a few days and patients receiving this kind of photodynamic therapy are advised against unnecessary exposure to bright light. TMD QDs such as MoS2 QDs may offer a safer alternative to these organic compounds as some transition metals like Mo are themselves essential minerals and can be quickly metabolised after the photodynamic treatment. We will conduct further tests to verify this.” Assoc Prof Leong added.

The potential of TMD QDs, however, goes far beyond just biomedical applications. Moving forward, the team is working on expanding its library of TMD QDs using the bottom-up strategy, and to optimise them for other applications such as the next generation TV and electronic device screens, advanced electronics components and even solar cells.

Tags:  2D materials  Graphene 

Share |
PermalinkComments (0)
 

Gratomic and TODAQ announce supply chain partnership to track commercial graphene from source to end consumer on the TODA protocol

Posted By Graphene Council, The Graphene Council, Monday, February 4, 2019
Updated: Thursday, January 31, 2019
Gratomic Inc. and TODAQ Holdings are pleased to announce that they have entered into a memorandum of understanding describing the terms of a supply chain partnership to put Gratomic's supply chain and products on the TODA Protocol.

"The market for tires requires products that deliver fuel efficiency, safe handling, and extended wear.  Integrating Gratomic's operations and products onto the TODA-as-a-service ("TaaS") platform with TODAQ as a partner allows us to deliver the desired product efficiently and effectively into the customers hands, with the peace of mind of knowing what they own has been monitored from the raw material source through to the finished product,"said Gratomic's Chairman and co-CEO Sheldon Inwentash.

The project will focus on providing incontrovertible proof of provenance in respect of Gratomic's graphite supply and consequent synthesis of commercial nano engineered graphene products throughout the global graphene marketplace down to the end consumer. 

"We're pleased to add Gratomic as our mining partner alongside our other pharmaceutical and energy supply chain projects. TODAQ is looking forward to adding efficiency and security with scale to Gratomic's operations, providing a brand multiplier that adds confidence to products carrying liberated nano engineered graphene from Gratomic's dedicated graphite source, and of course addressing the potential for forgeries and fakes that can become a constant source of leakage," said Sung Soo Park, TODAQ Managing Director in Seoul.

The project will be rolled out in stages over 2019 as Gratomic brings its end products to market starting with first proof of concepts and staging to commercial delivery of its fuel efficient tire in collaboration with its development partner, Perpetuus Carbon Technologies.  

"Our Graphite mine in Namibia delivers some of the highest quality exceptionally friable graphite for ease of commercial processing. A methodology for monitoring which graphite source is processed into a specific product is a game changer," said Arno Brand, Gratomic's co-CEO.

It is expected that the complete project will span multiple continents with peer-to-peer cross-border settlement of transactions in less than a minute, and aim to efficiently demonstrate results that can commercially scale up looking into 2020. Later phases will also aim to include value-added trade finance services on the TaaS platform.

"The TODA Protocol ensures individual ownership of your own data and TODAQ is here to enable secure and efficient international trade and commoditize the settlement of value. The beauty of this project is that once a customer buys graphene ultra-efficient tires, they own that digital asset and embedded proof of the tire, without requiring any other intermediary including the mine, processor, manufacturing company, retail source or even TODAQ," said TODAQ CEO, Hassan Khan.

Tags:  Graphene  Gratomic  TODAQ Holdings 

Share |
PermalinkComments (0)
 

Women in Graphene Career Development Day

Posted By Graphene Council, The Graphene Council, Monday, February 4, 2019
Updated: Monday, February 4, 2019

The "Women In Graphene" initiative within the Graphene Flagship has been set up to help support women and create a more gender diverse scientific community. It aims to connect women working in graphene through biannual meetings and peer to peer support.



Many industries are faced with problems when it comes to gender equality. For example, 99% of female chemists experience a lack of progression in their sector, according to evidence given by the Royal Society of Chemistry (RSC).

The Graphene Flagship, one of our Future & Emerging Technologies (FET) Flagships will host a two day programme – the Women in Graphene Career Development Day – with seminars and workshops aiming to encourage diversity within this field’s community.

This will take place at the National Graphene Institute at the University of Manchester, UK between 11 and 12 February 2019 to coincide with the International Day of Women and Girls in STEM (science, technology, engineering and maths) with the objective of establishing a peer-to-peer support network and reoccurring bi-annual meetings.

NOTICE: THIS EVENT IS NOW FULLY BOOKED!


Tags:  Graphene  The Graphene Flagship 

Share |
PermalinkComments (0)
 

Leading Supplier to Composites Companies Adds Graphene to Its Portfolio

Posted By Dexter Johnson, IEEE Spectrum, Friday, February 1, 2019

 

 

As an association trying to support and promote the use of graphene over the last half-decade, The Graphene Council has rightly focused on the interests and developments of the graphene research community as well as those companies marketing graphene materials. In addition, the Council has also sought to serve as an educational platform to help inform other vertical industries about the impact graphene can make on their businesses.

The Graphene Council recently got a boost to its knowledge base on how graphene is perceived by its largest commercial market: composites. Composites Onethe leading supplier in North America of materials and solutions to advanced composites manufacturers, recently joined The Graphene Council as a corporate member. Composites One positions itself as a team of composites experts that can provide insights on the latest advanced materials ranging from advanced fibers, to high-performance thermosets and thermoplastic systems, prepregs, and specialty core materials. The Graphene Council believes Composites One's expertise should reinforce its own knowledge that can then be distributed throughout our community.

To start this knowledge sharing, we took the opportunity to ask Jason Gibson, the Chief Applications Engineer at Composites One, a little bit about their business, how they came to graphene and what kind of outlook the company has for graphene in the composites market.

Q: Could you tell us a bit more about Composites One business, i.e. what kind of composites are you making and for what applications?

A: As North America’s leading provider of solutions for advanced composites manufacturers, Composites One stands ready to assist you, whatever your needs. We utilize the broadest portfolio of advanced raw materials to build comprehensive solutions, bringing you multiple options to meet your needs. Composites One supports our offering with strong technical expertise, along with local service and storage for reduced lead times. We are uniquely capable of handling complex requirements.

Our network of 41 stocking centers throughout the U.S. and Canada, including AS9120 and prepreg freezer locations, along with local delivery on our own fleet of trucks, ensures that your products are there when you need them. All of this is supported by a dedicated team of advanced composites specialists and our 80+ local technical sales representatives.

Q: What are some of the more advanced materials that Composites One has investigated for possibly integrating into your composite offerings?

A: From advanced fibers, to high-performance thermoset and thermoplastic systems, prepregs, specialty core materials, and ancillary products, we have the broadest product offering in the industry.   Our Advanced Composites product managers are specialists in epoxy resin, prepreg, carbon fiber, high performance core, and many other advanced composites solutions.

Q: What made you consider using graphene as a material for your composites, i.e. have you seen other composite manufacturers employing the material, or is it simple due diligence for all emerging materials?

A: We have seen graphene enhance many of the physical properties across the portfolio of resin systems we distribute.  Specifically, we've seen improved toughness, modulus and strength improvements allowing us to fill the needs of engineers and designers at many of our customers.  Composites One focuses on evaluating and distributing cutting edge products that allow us to help our customers meet their goals of improved products.

Q: Can you outline the process by which you would need to test to see if graphene, or any other new material, could be, or should be, integrated into your composites?

A: Composites One works in partnership with our suppliers, industry organizations and academic resources to vet and validate many nano-particles, including graphene.  We maintain a portfolio of diverse nano-particle products that enable us to provide objective solutions to our customers' needs.  This allows us to focus on an optimized solution based on the unique requirements of our customer.

Q: Based on your initial impressions of graphene, where are you expecting the material to fit into your product offerings?

A: We offer graphene in masterbatch form in multiple resin platforms, but focused mainly in our epoxy offerings.  Loadings can vary depending on the desired end results, and offering the masterbatch in the resin side of the epoxy allows for alternative hardening and additive solutions.  We have seen these products have success in multiple markets including sports and recreation, oil and gas, automotive and aerospace.

Q: At this point, what seems to be the issues that remain unclear about graphene, i.e. industry standards, how it will actually integrate into your composites, etc.?

A: Implementing these products into an industrial manufacturing process can be difficult.  Composites One has extensive experience in the process-ability of the nanoparticle enhancements we offer.  We do this in order to help our customers get over the usual hurdle of incorporating it into their manufacturing process.  It can be difficult to implement these solutions and our breadth and depth of experience in this product lines allows us to partner with our customers and help them move forward with minimal difficulties.

Tags:  composites  Composites One  masterbatches  prepregs  thermosets 

Share |
PermalinkComments (0)
 

Materials design center receives $25 million grant

Posted By Graphene Council, The Graphene Council, Thursday, January 31, 2019
After spending the past five years solidifying Chicago as a hub for high-tech materials innovation, the second phase of the Chicago-based Center for Hierarchical Materials Design (CHiMaD) has been selected for funding. The National Institute of Standards and Technology (NIST) granted the multi-institutional, Chicago-based center an additional $25 million over the next five years.

CHiMaD is hosted by Northwestern University, with partners that include the University of Chicago, Argonne National Laboratory, QuesTek Innovations and ASM Materials Education Foundation. NIST is also a major collaborator with more than 50 investigators involved in CHiMaD research.

CHiMaD’s mission is to develop a new generation of computational tools, databases and experimental techniques that will enable the design of novel materials to address major societal challenges. The center is also transferring these tools and techniques to industry as well as training the next generation of materials innovators.

“CHiMaD’s central goal is to realize the promise of the Materials Genome Initiative,” said Peter Voorhees, the Frank C. Engelhart Professor of Materials Science and Engineering in Northwestern’s McCormick School of Engineering and one of the center’s three co-directors. “We are designing new materials, ranging from polymers for nanoelectronics to high-temperature metal alloys with the aim to facilitate a faster industrial design cycle of these materials while lowering manufacturing costs. We will also continue to enhance one of the world’s largest public domain collections of materials data that is at the core of our materials design effort.

Gregory B. Olson, the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern and co-director for the center, said: “Building on the Materials Genome infrastructure established in our first five years, we look forward to demonstrating a general methodology of computational materials design by applying our fundamental databases to the creation of novel, high-performance materials for applications ranging from electronics to space travel.”

“CHiMaD brings together the intellectual heft of two major universities in the area of materials design innovation — a national laboratory with deep expertise in materials and advanced computing, a startup company at the forefront of computational materials design, and the processing, characterization and development prowess of NIST,” said Juan de Pablo, the Liew Family Professor in Molecular Engineering and the Vice President for National Laboratories at the University of Chicago and co-director for the center. He continued, “By forming meaningful partnerships with leading companies that rely on fast design cycles to bring products to market at an accelerated pace, CHiMaD has established itself as a national and international thought center for materials innovation at the forefront of technology. The next phase of CHiMaD promises to result in exciting new discoveries that will rapidly find their way into products.” 

Designing materials employs physical theory, advanced computer models, vast materials properties databases and complex computations to accelerate the design of a new material with specific properties for a particular application. Since it launched in 2014, nearly 300 CHiMaD and NIST investigators have developed new materials for batteries, precision nanofabrication, electronics, inks for 3D printing, and structures to withstand extreme environments and more.

CHiMaD specifically focuses on the creation of novel “hierarchical materials,” which exploit distinct structural details at various scales — from the atomic on up — to achieve special, enhanced properties. An example in nature of a hierarchical material is bone, a composite of mineral and protein at the molecular level assembled into microscopic fibrils that in turn are assembled into hollow fibers and on up to the highly complex material that is “bone.” 

CHiMaD works to advance the national Materials Genome Initiative, which aims to accelerate the pace of new materials discovery by combining theoretical, computational and experimental science. Techniques for designing materials have the potential to revolutionize the development of new advanced materials, which in turn have created whole industries. It’s estimated that the average time from laboratory discovery of a new material to its first commercial use can take up to 20 years. The Materials Genome Initiative aims to halve that.

Tags:  Center for Hierarchical Materials Design  CHiMaD  National Institute of Standards and Technology  NIST 

Share |
PermalinkComments (0)
 

Promising steps towards large scale production of graphene nanoribbons for electronics

Posted By Graphene Council, The Graphene Council, Thursday, January 31, 2019
Two-dimensional sheets of graphene in the form of ribbons a few tens of nanometers across have unique properties that are highly interesting for use in future electronics. Researchers have now for the first time fully characterised nanoribbons grown in both the two possible configurations on the same wafer with a clear route towards upscaling the production.

Graphene in the form of nanoribbons show so called ballistic transport, which means that the material does not heat up when a current flow through it. This opens up an interesting path towards high speed, low power nanoelectronics. The nanoribbon form may also let graphene behave more like a semiconductor, which is the type of material found in transistors and diodes. The properties of graphene nanoribbons are closely related to the precise structure of the edges of the ribbon. Also, the symmetry of the graphene structure lets the edges take two different configurations, so called zigzag and armchair, depending on the direction of the long respective short edge of the ribbon.

The nanoribbons were grown in two directions along ridges on the substrate. This way both the zigzag- and armchair-edge varieties form and can be studied at the same time. The positions of the atoms in the graphene layer as well as the zig zag edge can be seen from the scanning tunneling microscopy image (Å stands for Ångström, 0.1 nanometers).

The nanoribbons were grown on a template made of silicon carbide under well controlled conditions and thoroughly characterised by a research team from MAX IV Laboratory, Technische Universität Chemnitz, Leibniz Universität Hannover, and Linköping University. The template has ridges running in two different crystallographic directions to let both the armchair and zig-zag varieties of graphene nanoribbons form. The result is a predictable growth of high-quality graphene nanoribbons which have a homogeneity over a millimeter scale and a well-controlled edge structure.

One of the new findings is that the researchers were able to show ballistic transport in the bulk of the nanoribbon. This was possible due to extremely challenging four probe experiments performed at a length scale below 100 nm by the group in Chemnitz, says Alexei Zakharov, one of the authors.

The electrical characterization also shows that the resistance is many times higher in the so called armchair configuration of the ribbon, as opposed to the lower resistance zig-zag form obtained. This hints to a possible band gap opening in the armchair nanoribbons, making them semiconducting. The process used for preparing the template for nanoribbon growth is readily scalable. This means that it would work well for development into the large-scale production of graphene nanoribbons needed to make them a good candidate for a future material in the electronics industry.

So far, we have been looking at nanoribbons which are 30–40 nanometers wide. It’s challenging to make nanoribbons that are 10 nanometers or less, but they would have very interesting electrical properties, and there´s a plan to do that. Then we will also study them at the MAXPEEM beamline, says Zakharov.

The measurements performed at the MAXPEEM beamline was done with a technique not requiring X-rays. The beamline will go into its commissioning phase this spring and will start welcoming users this year.

Tags:  2d materials  Graphene  graphene production 

Share |
PermalinkComments (0)
 

Open-source automated chemical vapor deposition system for the production of two-dimensional nanomaterials

Posted By Graphene Council, The Graphene Council, Wednesday, January 30, 2019
Updated: Tuesday, January 29, 2019
A research group at Boise State University led by Assistant Professor David Estrada of the Micron School of Materials Science and Engineering has released the open-source design of a chemical vapor deposition (CVD) system for two-dimensional (2D) materials growth, an advance which could lower the barrier of entry into 2D materials research and expedite 2D materials discovery and translation from the benchtop to the market.

2-dimensional materials are a class of materials that are one to a few atoms thick. The pioneering work of Nobel Laureates Andre Geim and Konstantin Novoselov in isolating and measuring the physical properties of graphene – a 2D form of carbon arranged in a hexagonal crystal structure - ignited the field of 2D materials research

While 2D materials can be obtained from bulk van der Waals crystals (e.g. graphite and MoS2) using a micromechanical cleavage approach enabled by adhesive tapes, the community quickly realized that unlocking the full potential of 2D materials would require advanced manufacturing methods compatible with the semiconductor industry’s infrastructure.

Chemical vapor deposition is a promising approach for scalable synthesis of 2D materials – but automated commercial systems can be cost prohibitive for some research groups and startup companies. In such situations students are often tasked with building custom furnaces, which can be burdensome and time consuming. While there is value in such endeavors, this can limit productivity and increase time to degree completion.

A recent trend in the scientific community has been to develop open-source hardware and software to reduce equipment cost and expedite scientific discovery. Advances in open-source 3-dimensional printing and microcontrollers have resulted in freely available designs of scientific equipment ranging from test tube holders, potentiostats, syringe pumps and microscopes. Estrada and his colleagues have now added a variable pressure chemical vapor deposition system to the inventory of open-source scientific equipment.

“As a graduate student I was fortunate enough that my advisor was able to purchase a commercial chemical vapor deposition system which greatly impacted our ability to quickly grow carbon nanotubes and graphene. This was critical to advancing our scientific investigations,” said Estrada. “When I read scientific articles I am intrigued with the use of the phrase “custom-built furnace” as I now realize how much time and effort graduate students invest in such endeavors.”

The design and qualification of the furnace was accomplished by lead authors Dale Brown, a former Micron School of Materials Science and Engineering graduate student, and Clinical Assistant faculty member Lizandra Godwin, with assistance from the other co-authors. The results of their variable pressure CVD system have been published in PLoS One ("Open-source automated chemical vapor deposition system for the production of two- dimensional nanomaterials") and include the parts list, software drivers, assembly instructions and programs for automated control of synthesis procedures. Using this furnace, the team has demonstrated the growth of graphene, graphene foam, tungsten disulfide and tungsten disulfide – graphene heterostructures.

“Our goal in publishing this design is to alleviate the burden of designing and constructing CVD systems for the early stage graduate student,” said Godwin. “If we can save even a semester of time for a graduate student this can have a significant impact on their time to graduation and their ability to focus on research and advancing the field.”

“We hope others in the community can improve on our design by incorporating open-source software for automated control of 2D materials synthesis,” said Estrada. “Such an improvement could further reduce the barrier to entry for 2D materials research.”

Tags:  2D materials  Boise State University  CVD  Graphene 

Share |
PermalinkComments (0)
 

Properties of ‘wonder material’ graphene change in humid conditions

Posted By Graphene Council, The Graphene Council, Tuesday, January 29, 2019
Updated: Friday, January 25, 2019

The ‘wonder material’, which is made from carbon and was discovered in 2004, is hailed for many of its extraordinary characteristics including being stronger than steel, more conductive than copper, light, flexible and transparent.



This study, published in the journal Physical Review B, shows that in bi-layer graphene, which is two sheets of one atom thick carbon stacked together, water seeps between the layers in a humid environment.

The properties of graphene significantly depend on how these carbon layers interact with each other and when water enters in between it can modify the interaction.

The researchers found the water forms an atomically thin layer at 22 per cent relative humidity and separates graphene layers at over 50 per cent relative humidity.

This suggests that layered graphene could exhibit very different properties in a humid place such as Manchester, UK, where average relative humidity is over 80 per cent every month of the year, compared to a dry place such as Tucson, Arizona, where relative humidity is 13 per cent on afternoons in May but rises to 65 per cent on January mornings. So, in Tucson the properties will vary according to the time of the year.

Graphene, both layered and single layer, potentially has a huge number of uses but the results of this study could impact how the material can be used in real-life applications.

Humidity needs to be recorded

Lead author Dr Yiwei Sun, from Queen Mary's School of Engineering and Materials Science, said: “The critical points, 22 per cent and 50 per cent relative humidity, are very common conditions in daily life and these points can be easily crossed. Hence, many of the extraordinary properties of graphene could be modified by water in between graphene layers.”

He added: “Some graphene-based devices may function to their full capability in dry places while others may do so in humid places. We suggest all experiments on 2D materials should in future record the relative humidity.”

The researchers suggest humidity is also likely to have an impact on other layered materials such as boron nitride (sheets made of boron and nitrogen) and Molybdenum disulphide (sheets made of molybdenum and sulphur).

The study was carried out because it was known that graphite, a material also made from carbon, loses its excellent lubricating ability in low humidity conditions, such as aboard aeroplanes at high altitude, which was reported during the Second World War, or in outer space, as reported by NASA in the 1970s.

It was believed that the water in between layers of graphite is crucial to its behaviour and now the same effect has been shown to affect layered graphene.  

Tags:  2D  Bi-layer graphene  Graphene  water  Yiwei Sun 

Share |
PermalinkComments (0)
 
Page 15 of 24
 |<   <<   <  10  |  11  |  12  |  13  |  14  |  15  |  16  |  17  |  18  |  19  |  20  >   >>   >|