Graphene Nanocomposite Foam Material Harvests Water from Air


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Researchers in China have demonstrated a graphene nanocomposite foam-based water harvesting system to harvest water from air. The team reports their findings in ACS Applied Materials & Interfaces (“Superelastic Graphene Nanocomposite for High Cycle-Stability Water Capture-Release under Sunlight”).
Only 30% of all freshwater on the planet is not locked up in ice caps or glaciers (not for much longer, though). Of that, some 20% is in areas too remote for humans to access and of the remaining 80% about three-quarters comes at the wrong time and place – in monsoons and floods – and is not always captured for use by people. The remainder is less than 0.08 of 1% of the total water on the planet (read more: “Nanotechnology and water treatment“)
An abundance of water equivalent to about 10% of the total freshwater in lakes exists in the earth atmosphere, which can be a non-negligible freshwater resource to fight against the water shortage.
That’s where the graphene nanocomposite foam comes in: The foam realizes water harvesting through a capture-release cycle:
1) the capture process is composed of moisture adsorption from air by lithium chloride (LiCl) and water preservation by poly(vinyl alcohol) (PVA) and
2) the release relies on the solar-to-thermal transformer, reduced graphene oxide (rGO), to facilitate evaporation. In addition, polyimide is employed as a substrate material for the purpose of 3D porous structure formation and mechanical property enhancement.

 

graphene nanocomposite foam for harvesting water from air
 

Photograph, schematic diagram, and SEM images of the graphene nanocomposite foam. (a) Photograph of the graphene nanocomposite foam. (b) Schematic diagram of the graphene nanocomposite foam. Foam was prepared through a three-step process: freeze-drying, thermal annealing, and hydrophilic treatment. rGO/PI nanosheet, as the basic unit, can achieve the water harvesting capture-release cycle without additional energy input. (c) SEM image presents a porous structure of the rGO/PI foam without hydrophilic treatment. (d) Magnified SEM image of the rGO/PI foam without hydrophilic treatment to show a relatively smooth surface of the nanosheet. (e) SEM image of the graphene nanocomposite foam after hydrophilic treatment. (f) Magnified SEM image of the hydrophilic rGO/PI foam with bumped nanostructures. (g) Schematic diagram of the water vapor capture-release cycle.

LiCl and PVA were responsible for the water capture and water storage, respectively. Adsorbed water was stored as crystallized water in LiCl hydrates and the free water molecules were restrained by hydroxyl groups on PVA through the hydrogen bond, which led to the transformation of the nanosheet from dry status to wet status. Opposite procedure, from wet status to dry status, was realized by the rGO converting the solar energy to thermal energy to facilitate water evaporation under irradiation. (Reprinted with permission by American Chemical Society) (click on image to enlarge)

 

The as-fabricated foam can adsorb water up to 2.87 g per gram in 24 hours at a relative humidity of 90% and a temperature of 30°C, and release almost all the uptake water when it is exposed under a flux of 1 sun (1000 W per square meter, equal to the light intensity of natural sunlight) for 3 hours.
At the same time, the functional foam shows superelasticity, lightweight, and remarkable reusability, thus revealing its possibility to practical use.
The researchers write that, even though the rGO/PI nanocomposite foam can harvest freshwater from air, it is essential to enhance water harvesting efficiency.
“Another big challenge impedes the water harvesting system utilization to explore a more cost-effective way to prepare the products,” they conclude. “Though the three-step synthesis method and the composition of the foam have been optimized, it is still necessary to reduce the cost and increase the fabrication efficiency. Meanwhile, environmentally friendly materials are recommended, which would take the water harvesting system one step further to commercial application and large-scale production.”
By Michael Berger – Nanowerk

Sources

Bo ChenXue Zhao, and Ya Yang*§ 
 CAS Center for Excellence in Nanoscience, Beijing Key Laboratory of Micro-Nano Energy and Sensor, Beijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciences, Beijing 100083, P. R. China
 School of Nanoscience and TechnologyUniversity of Chinese Academy of Sciences, Beijing 100049, P. R. China
§ Center on Nanoenergy Research, School of Physical Science and TechnologyGuangxi University, Nanning, Guangxi 530004, P. R. China
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Genesis Nanotech – ICYMI – Our Top 3 Blog Posts (as picked by you) This Week


#1

MIT Review: Borophene (not graphene) is the new wonder material that’s got everyone excited

#2

China made an artificial star that’s 6 times (6X) as hot as our sun … And it could be the future of energy

 

#3

Graphene Coating Could Help Prevent Lithium Battery Fires

 

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Graphene Coating could help Prevent Lithium Battery Fires


Car in

Lithium batteries are what allow electric vehicles to travel several hundred miles on one charge. Their capacity for energy storage is well known, but so is their tendency to occasionally catch on fire—an occurrence known to battery researchers as “thermal runaway.” These fires occur most frequently when the batteries overheat or cycle rapidly. With more and more electric vehicles on the road each year, battery technology needs to adapt to reduce the likelihood of these dangerous and catastrophic fires.

Researchers from the University of Illinois at Chicago College of Engineering report that graphene—wonder material of the 21st century—may take the oxygen out of lithium battery fires. They report their findings in the journal Advanced Functional Materials.

The reasons  catch fire include rapid cycling or charging and discharging, and  in the battery. These conditions can cause the cathode inside the battery—which in the case of most lithium batteries is a lithium-containing oxide, usually lithium cobalt oxide—to decompose and release oxygen. If the oxygen combines with other flammable products given off through decomposition of the electrolyte under high enough heat, spontaneous combustion can occur.

“We thought that if there was a way to prevent the oxygen from leaving the cathode and mixing with other flammable products in the battery, we could reduce the chances of a fire occurring,” said Reza Shahbazian-Yassar, associate professor of mechanical and industrial engineering in the UIC College of Engineering and corresponding author of the paper.

It turns out that a material Shahbazian-Yassar is very familiar with provided a perfect solution to this problem. That material is graphene—a super-thin layer of carbon atoms with unique properties. Shahbazian-Yassar and his colleagues previously had used graphene to help modulate lithium buildup on electrodes in lithium metal batteries.

graphenecoat

Lithium cobalt oxide particles coated in graphene. Credit: Reza Shahbazian-Yassar.

Shahbazian-Yassar and his colleagues knew that graphene sheets are impermeable to oxygen atoms. Graphene is also strong, flexible and can be made to be electrically conductive. Shahbazian-Yassar and Soroosh Sharifi-Asl, a graduate student in mechanical and  at UIC and lead author of the paper, thought that if they wrapped very small particles of the lithium cobalt oxide cathode of a lithium battery in graphene, it might prevent oxygen from escaping.

First, the researchers chemically altered the graphene to make it electrically conductive. Next, they wrapped the tiny particles of lithium cobalt oxide cathode electrode in the conductive graphene.

When they looked at the -wrapped lithium cobalt oxide particles using electron microscopy, they saw that the release of oxygen under high heat was reduced significantly compared with unwrapped particles.

Next, they bound together the wrapped particles with a binding material to form a usable cathode, and incorporated it into a lithium metal battery. When they measured released oxygen during battery cycling, they saw almost no oxygen escaping from cathodes even at very high voltages. The lithium metal battery continued to perform well even after 200 cycles.

“The wrapped cathode battery lost only about 14% of its capacity after rapid cycling compared to a conventional  metal battery where performance was down about 45% under the same conditions,” Sharifi-Asl said.

“Graphene is the ideal material for blocking the release of oxygen into the electrolyte,” Shahbazian-Yassar said. “It is impermeable to oxygen, electrically conductive, flexible, and is strong enough to withstand conditions within the battery. It is only a few nanometers thick so there would be no extra mass added to the . Our research shows that its use in the  can reliably reduce the release of  and could be one way that the risk for fire in these batteries—which power everything from our phones to our cars—could be significantly reduced.”


Explore further

Liquid microscopy technique reveals new problem with lithium-oxygen batteries

Purdue University: A New hybrid energy method with Highly Porous Graphene Foams – Could Fuel the Future of Rockets, Space Exploration


newhybridene
Purdue University researchers have developed a new propellant formulation method to use graphene foams to power spacecraft. Credit: Purdue University

Graphene, a new material with applications in biomedical technology, electronics, composites, energy and sensors, may soon help send rockets to space.

A new  formulation method to use  foams – material used in electronics, optics and  – to power spacecraft is being developed in Purdue University’s Maurice J. Zucrow Laboratories, which is the largest academic propulsion lab in the world. The research is showing success at increasing burn rate of solid propellants that are used to fuel rockets and spacecraft.

“Our propulsion and physics researchers came together to focus on a material that has not previously been used in rocket propulsion, and it is demonstrating strong results,” said Li Qiao, an associate professor of aeronautics and astronautics in Purdue’s College of Engineering.

The research team, led by Qiao, developed methods of making and using compositions with solid fuel loaded on highly conductive, highly porous graphene foams for enhanced burn rates for the loaded . They wanted to maximize the catalytic effect of metal oxide additives commonly used in solid propellant to enhance decomposition.

The graphene  structures are also thermally stable, even at , and can be reused. The developed compositions provide significantly improved burn rate and reusability.

New hybrid energy method could fuel the future of rockets, spacecraft for exploration

A new propellant formulation method to use porous graphene foams to power spacecraft is being developed at Purdue University. Credit: Purdue University

Qiao said the graphene foam works well for solid propellants because it is super lightweight and highly porous, which means it has many holes in which scientists can pour fuel to help ignite a rocket launch.

The graphene foam has a 3-D, interconnected structure to allow a more efficient thermal transport pathway for heat to quickly spread and ignite the propellant.

“Our patented technology provides higher performance that is especially important when looking at areas such as hypersonics,” Qiao said. “Our tests showed a burn rate enhancement of nine times the normal, using functionalized graphene foam structures.”

Qiao said the Purdue graphene foam discovery has applications for energy conversion devices and missile defense systems, along with other areas where tailoring nanomaterials for specific outcomes may be useful.


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New technologies could solve rocket challenges 800 years in the making

MIT Review: Borophene (not graphene) is the new wonder material that’s got everyone excited


Stronger and more flexible than graphene, a single-atom layer of boron could revolutionize sensors, batteries, and catalytic chemistry.

Not so long ago, graphene was the great new wonder material. A super-strong, atom-thick sheet of carbon “chicken wire,” it can form tubes, balls, and other curious shapes.

And because it conducts electricity, materials scientists raised the prospect of a new era of graphene-based computer processing and a lucrative graphene chip industry to boot. The European Union invested €1 billion to kick-start a graphene industry.

This brave new graphene-based world has yet to materialize. But it has triggered an interest in other two-dimensional materials. And the most exciting of all is borophene: a single layer of boron atoms that form various crystalline structures.

The reason for the excitement is the extraordinary range of applications that borophene looks good for. Electrochemists think borophene could become the anode material in a new generation of more powerful lithium-ion batteries.

Read More: Borophene Discoveries at Rice University

Chemists are entranced by its catalytic capabilities. And physicists are testing its abilities as a sensor to detect numerous kinds of atoms and molecules.

Today, Zhi-Qiang Wang at Xiamen University in China and a number of colleagues review the remarkable properties of borophene and the applications they might lead to.

Borophene has a short history. Physicists first predicted its existence in the 1990s using computer simulations to show how boron atoms could form a monolayer.

But this exotic substance wasn’t synthesized until 2015, using chemical vapor deposition. This is a process in which a hot gas of boron atoms condenses onto a cool surface of pure silver.

The regular arrangement of silver atoms forces boron atoms into a similar pattern, each binding to as many as six other atoms to create a flat hexagonal structure. However, a significant proportion of boron atoms bind only with four or five other atoms, and this creates vacancies in the structure. The pattern of vacancies is what gives borophene crystals their unique properties.

Since borophene’s synthesis, chemists have been eagerly characterizing its properties. Borophene turns out to be stronger than graphene, and more flexible. It a good conductor of both electricity and heat, and it also superconducts. These properties vary depending on the material’s orientation and the arrangement of vacancies. This makes it “tunable,” at least in principle. That’s one reason chemists are so excited.

Borophene is also light and fairly reactive. That makes it a good candidate for storing metal ions in batteries. “Borophene is a promising anode material for Li, Na, and Mg ion batteries due to high theoretical specific capacities, excellent electronic conductivity and outstanding ion transport properties,” say Wang and co.

Hydrogen atoms also stick easily to borophene’s single-layer structure, and this adsorption property, combined with the huge surface area of atomic layers, makes borophene a promising material for hydrogen storage. Theoretical studies suggest borophene could store over 15% of its weight in hydrogen, significantly outperforming other materials.

Then there is borophene’s ability to catalyze the breakdown of molecular hydrogen into hydrogen ions, and water into hydrogen and oxygen ions.

“Outstanding catalytic performances of borophene have been found in hydrogen evolution reaction, oxygen reduction reaction, oxygen evolution reaction, and CO2 electroreduction reaction,” say the team. That could usher in a new era of water-based energy cycles.

Nevertheless, chemists have some work to do before borophene can be more widely used. For a start, they have yet to find a way to make borophene in large quantities.

And the material’s reactivity means it is vulnerable to oxidation, so it needs to be carefully protected. Both factors make borophene expensive to make and hard to handle. So there is work ahead.

But chemists have great faith. Borophene may just become the next wonder material to entrance the world.

Ref: arxiv.org/abs/1903.11304 : Review of borophene and its potential applications

From MIT Technology Review March 2019

 

Novel Graphene Film Offers New Concept for Solar Energy and Solar Seawater Desalination


Ultrathin-graphene-film-for-solar-energy-image-img_assist-400x254

Researchers at Swinburne, the University of Sydney and Australian National University have collaborated to develop a solar absorbing, ultra-thin graphene-based film with unique properties that has great potential for use in solar thermal energy harvesting.

The 90 nanometre material is said to be a 1000 times finer than a human hair and is able to rapidly heat up to 160°C under natural sunlight in an open environment.

The team stated that this new graphene-based material may also open new avenues in:

  • thermophotovoltaics (the direct conversion of heat to electricity)
  • solar seawater desalination
  • infrared light source and heater
  • optical components: modulators and interconnects for communication devices
  • photodetectors
  • colorful display
  • It could possibly lead to the development of ‘invisible cloaking technology’ through developing large-scale thin films enclosing the objects to be ‘hidden’.

The researchers have developed a 2.5cm x 5cm working prototype to demonstrate the photo-thermal performance of the graphene-based metamaterial absorber. They have also proposed a scalable manufacturing strategy to fabricate the proposed graphene-based absorber at low cost.

“This is among many graphene innovations in our group,” says Professor Baohua Jia, Research Leader, Nanophotonic Solar Technology, in Swinburne’s Center for Micro-Photonics.

“In this work, the reduced graphene oxide layer and grating structures were coated with a solution and fabricated by a laser nanofabrication method, respectively, which are both scalable and low cost.”

‌‌“Our cost-effective and scalable graphene absorber is promising for integrated, large-scale applications that require polarisation-independent, angle insensitive and broad bandwidth absorption, such as energy-harvesting, thermal emitters, optical interconnects, photodetectors and optical modulators,” says first author of this research paper, Dr Han Lin, Senior Research Fellow in Swinburne’s Center for Micro-Photonics.

“Fabrication on a flexible substrate and the robustness stemming from graphene make it suitable for industrial use,” Dr Keng-Te Lin, another author, added.

“The physical effect causing this outstanding absorption in such a thin layer is quite general and thereby opens up a lot of exciting applications,” says Dr Bjorn Sturmberg, who completed his PhD in physics at the University of Sydney in 2016 and now holds a position at the Australian National University.

“The result shows what can be achieved through collaboration between different universities, in this case with the University of Sydney and Swinburne, each bringing in their own expertise to discover new science and applications for our science,” says Professor Martijn de Sterke, Director of the Institute of Photonics and Optical Science.

“Through our collaboration we came up with a very innovative and successful result. We have essentially developed a new class of optical material, the properties of which can be tuned for multiple uses.”

Source:  Swinburne

Graphene quantum dots for single electron transistors ~ Application for Future Electronics


The schematic structure of the devices

Scientists from Manchester University, the Ulsan National Institute of Science & Technology and the Korea Institute of Science and Technology have developed a novel technology, which combines the fabrication procedures of planar and vertical heterostructures in order to assemble graphene-based single-electron transistors.

In the study, it was demonstrated that high-quality graphene quantum dots (GQDs), regardless of whether they were ordered or randomly distributed, could be successfully synthesized in a matrix of monolayer hexagonal boron nitride (hBN).

Here, the growth of GQDs within the layer of hBN was shown to be catalytically supported by the platinum (Pt) nanoparticles distributed in-between the hBN and supporting oxidised silicon (SiO2) wafer, when the whole structure was treated by the heat in the methane gas (CH4). It was also shown, that due to the same lattice structure (hexagonal) and small lattice mismatch (~1.5%) of graphene and hBN, graphene islands grow in the hBN with passivated edge states, thereby giving rise to the formation of defect-less quantum dots embedded in the hBN monolayer.

Such planar heterostructures incorporated by means of standard dry-transfer as mid-layers into the regular structure of vertical tunnelling transistors (Si/SiO2/hBN/Gr/hBN/GQDs/hBN/Gr/hBN; here Gr refers to monolayer graphene and GQDs refers to the layer of hBN with the embedded graphene quantum dots) were studied through tunnel spectroscopy at low temperatures (3He, 250mK).

The study demonstrated where the manifestation of well-established phenomena of the Coulomb blockade for each graphene quantum dot as a separate single electron transmission channel occurs.

‘Although the outstanding quality of our single electron transistors could be used for the development of future electronics, “This work is most valuable from a technological standpoint as it suggests a new platform for the investigation of physical properties of various materials through a combination of planar and van der Waals heterostructures.” as explained study co-author Davit Ghazaryan, Associate Professor at the HSE Faculty of Physics, and Research Fellow at the Institute of Solid State Physics (RAS)

A Conversation with Professor (Sir) Kostya Novoselov, Co-Nobel Prize Winner in Physics 2019 ~ Research into “The Graphene Flagship” and other 2D materials


Talking with SciTech Europa, Professor Novoselov, co-awarded the 2019 Nobel Prize in Physics, for the discovery and isolation of a single atomic layer of carbon for the first time, explores the research into Graphene Flagship and other 2D materials.

At the University of Manchester, UK, in 2004, Professor Sir Kostya Novoselov, along with his colleague Professor Sir Andre Geim, discovered and isolated a single atomic layer of carbon for the first time. The pair received the Nobel Prize in Physics in 2010 in recognition of their breakthrough.

On 28 January 2013, the European Commission announced that, out of the six pilot preparatory actions put forward for the Future and Emerging Technology (FET) Flagships competition, the Graphene Flagship, along with the Human Brain Project, had been selected to receive €1bn in funding over the course of a decade, tasking it with bringing together academic and industrial researchers to take graphene from the realm of academic laboratories into European society, thereby generating economic growth, new jobs, and new opportunities.

In February, SciTech Europa attended the Mobile World Congress in Barcelona, Spain. This event is the world’s largest exhibition for the mobile industry, and where, for the fourth consecutive year, the Graphene Flagship hosted its Graphene Pavilion – this year showcasing over 20 different graphene-based working prototypes and devices that will transform future telecommunications.

At the pavilion, SEQ met with Professor Novoselov to discuss research into graphene and other two dimensional materials, as well as how the Flagship is working to bolster both fundamental research and applications stemming from these advanced materials.

What do you think have been the biggest, and latest, developments in graphene (and other 2D materials) research?

There has been a lot of progress in recent years and, indeed, we are no longer talking only about graphene, but also about many other two dimensional materials as well.

First of all – new applications of graphene is one example of recent developments – we see new applications emerging on an almost monthly basis. Second, there is still a lot of progress being made in fundamental research on graphene and 2D materials. And those fundamental results are being implemented in applications.

In terms of other new 2D materials, there is a lot of activity on ferromagnetic materials.

What potential is there now to move graphene forwards, and how would you describe the role of the Flagship in this?

The basic technology is in place, and so what is important now is for entrepreneurs and SMEs to convert those developments into commercial applications, and, indeed, we need to help them to do so.

The Flagship, of course, has now reached the half way stage, and we therefore need to carefully balance the amount of effort we place on applications with the effort we place on the development of fundamental science, which remains crucial.

Nevertheless, we also need to ensure we are helping companies and industry to introduce this material into real products, and that is actually much more difficult, not least because of the fact that this has not been done at this scale before, and so nobody knows how to do it yet.

Are you able to utilise EU instruments to help fund commercialisation activities?

It is not necessarily funding that is a problem in in Europe; the challenge comes more in the form of bringing together scientists, entrepreneurs, and funders in the same room, and it is still not clear how to achieve that. There is thus the argument that we need to work more closely with entrepreneurs and we need to grow those entrepreneurs who are working on advanced materials because this is a much more challenging area than, say, ‘.com’ applications.

What do you feel are the biggest barriers here?

It is perhaps the mentality that exists around risk taking that needs to change. Bringing together entrepreneurs, scientists, the technology and the money around the same table is a challenge and, as I have mentioned, it needs to be understood that bringing new materials, especially nanomaterials, to market is much more challenging than it is to bring, for example, new software to consumers.

And, of course, the level of required investment is also much larger. Whether we have enough people in Europe who are ready to take this risk is a good question.

Would you say that Europe is too risk averse when it comes to this type of investment in comparison to, for instance, the USA?

Perhaps; there is certainly a sense that Europe needs to work much harder than the USA or South-East Asia. And the reason for that is not only a lack of those willing to take enhanced risks, but also the level and mobility of the available money and, indeed, how soon financiers expect a return on their investment.

Could 2D materials research spark a ‘revolution’ in real world applications?

I am not sure that we will see a ‘revolution’; the growth in real world applications utilising graphene is, and will continue to be, a gradual introduction. That is not to say, however, that this gradual process won’t speed up a little over time.

And it is great to see that, when it comes to graphene, this introduction, although gradual, is already happening much faster than with any other advanced material that we have seen before. The purpose of the Flagship is to help speed up this process.

The Flagship is now investing in research into the safety of graphene. How important is that?

This is an example of the sort of issue where the Flagship should take the initiative, because it is not only about graphene; we need to realise that many new nanomaterials are going to play an increasing role in the everyday lives of people, and we need to be prepared for that.

There are a great many regulations which have to be passed when bringing such advanced materials to market, including health and safety and toxicology regulations, and very often these are not very well defined because, quite simply, we have never been in this situation before. It can also be quite expensive to run the necessary projects to investigate things like toxicology, and so it is important for projects like the Flagship to take the initiative and help businesses to overcome these barriers.

Where are your own research interests going to lie, moving forwards?

I do indeed conduct my own research, and within that graphene is not the largest part. I go beyond graphene and work on many other 2D materials and heterostructures, but it is nevertheless exciting to remember that it was graphene that made all the other materials possible as we work on those heterostructures towards new discoveries.

Professor Sir Kostya Novoselov
Nobel Laureate 
Director, National Graphene Institute at the University of Manchester
Member, Strategic Advisory Council, Graphene Flagship
Tweet @GrapheneCA @UoMGraphene

www.graphene.manchester.ac.uk/about/ngi
www.graphene-flagship.eu

Directa Plus to provide graphene for textile enhancement project with Loro Piana


It was recently announced that graphene technology developed by Directa Plus will be used to “enrich” textiles made by Italian high-end clothing and fabric maker Loro Piana.

The deal, which is for an initial duration of three years for a minimum value of €0.8 Million, will see Directa’s G+ graphene technology incorporated into some of Loro Piana’s fabrics and garments.

Giulio Cesareo, founder & chief executive of Directa Plus, said:

“The significant innovations in high quality fabrics that can be achieved through the use of Directa Plus’ technology will allow increased comfort and performance for the end users of Loro Piana’s products”.

Also Read About Nanotechnology in Smart Textiles and Wearables

The company said the hypoallergenic, non-toxic and sustainably produced nature of Loro Piana’s product range fitted “perfectly” with Directa’s own culture and values.

Breakthrough in the search for graphene-based electronics


graphene electronics gimage
A team of researchers from Denmark has solved one of the biggest challenges in making effective nanoelectronics based on graphene. The new results have just been published in Nature Nanotechnology.

For 15 years, scientists have tried to exploit the “miracle material” graphene to produce nanoscale electronics. On paper, graphene should be great for just that: it is ultra-thin – only one atom thick and therefore two-dimensional, it is excellent for conducting electrical current, and holds great promise for future forms of electronics that are faster and more energy efficient. In addition, graphene consists of carbon atoms – of which we have an unlimited supply.

In theory, graphene can be altered to perform many different tasks within e.g. electronics, photonics or sensors simply by cutting tiny patterns in it, as this fundamentally alters its quantum properties. One “simple” task, which has turned out to be surprisingly difficult, is to induce a band gap – which is crucial for making transistors and optoelectronic devices. However, since graphene is only an atom thick all of the atoms are important and even tiny irregularities in the pattern can destroy its properties.

“Graphene is a fantastic material, which I think will play a crucial role in making new nanoscale electronics. The problem is that it is extremely difficult to engineer the electrical properties,” says Peter Bøggild, professor at DTU Physics.

The Center for Nanostructured Graphene at DTU and Aalborg University was established in 2012 specifically to study how the electrical properties of graphene can be tailored by changing its shape on an extremely small scale. When actually patterning graphene, the team of researchers from DTU and Aalborg experienced the same as other researchers worldwide: it didn’t work.

“When you make patterns in a material like graphene, you do so in order to change its properties in a controlled way – to match your design. However, what we have seen throughout the years is that we can make the holes, but not without introducing so much disorder and contamination that it no longer behaves like graphene. It is a bit similar to making a water pipe that is partly blocked because of poor manufacturing. On the outside, it might look fine, but water cannot flow freely. For electronics, that is obviously disastrous,” says Peter Bøggild.

Now, the team of scientists have solved the problem. The results are published in Nature Nanotechnology. Two postdocs from DTU Physics, Bjarke Jessen and Lene Gammelgaard, first encapsulated graphene inside another two-dimensional material – hexagonal boron nitride, a non-conductive material that is often used for protecting graphene’s properties.

Next, they used a technique called electron beam lithography to carefully pattern the protective layer of boron nitride and graphene below with a dense array of ultra small holes. The holes have a diameter of approx. 20 nanometers, with just 12 nanometers between them – however, the roughness at the edge of the holes is less than 1 nanometer, or a billionth of a meter. This allows 1000 times more electrical current to flow than had been reported in such small graphene structures. And not just that.

“We have shown that we can control graphene’s band structure and design how it should behave. When we control the band structure, we have access to all of graphene’s properties – and we found to our surprise that some of the most subtle quantum electronic effects survive the dense patterning – that is extremely encouraging. Our work suggests that we can sit in front of the computer and design components and devices – or dream up something entirely new – and then go to the laboratory and realise them in practice,” says Peter Bøggild. He continues:

“Many scientists had long since abandoned attempting nanolithography in graphene on this scale, and it is quite a pity, since nanostructuring is a crucial tool for exploiting the most exciting features of graphene electronics and photonics. Now we have figured out how it can be done; one could say that the curse is lifted. There are other challenges, but the fact that we can tailor electronic properties of graphene is a big step towards creating new electronics with extremely small dimensions,” says Peter Bøggild.

About the Center for Nanostructured Graphene

• Funded by the Danish National Research Foundation with a total budget of 100 million DKK for the ten-year period 2012 – 2022. It focuses on basic research, but all its research projects have long-term perspectives for applications.

• the team is also part of the Graphene Flagship, which with a budget of €1 billion represents a new form of joint, coordinated research on an unprecedented scale, and is Europe’s biggest ever research initiative. It is tasked with bringing together academic and industrial partners to take graphene from the realm of academic laboratories into society in the space of 10 years, thus generating economic growth, new jobs and new opportunities for Europe.