Platinum-graphene fuel cell catalysts show superior stability over bulk platinum – Georgia Institute of Tecnology


Seung Soon Jang, an associate professor, Faisal Alamgir, an associate professor, and Ji Il Choi, a postdoctoral researcher, all in Georgia Tech’s School of Materials Science and Engineering, examine a piece of platinum-graphene catalyst. Credit: Allison Carter

Films of platinum only two atoms thick supported by graphene could enable fuel cell catalysts with unprecedented catalytic activity and longevity, according to a study published recently by researchers at the Georgia Institute of Technology.

Platinum is one of the most commonly used catalysts for fuel cells because of how effectively it enables the oxidation reduction reaction at the center of the technology. But its high cost has spurred research efforts to find ways to use smaller amounts of it while maintaining the same .

“There’s always going to be an initial cost for producing a fuel cell with , and it’s important to keep that cost as low as possible,” said Faisal Alamgir, an associate professor in Georgia Tech’s School of Materials Science and Engineering. “But the real cost of a fuel cell system is calculated by how long that system lasts, and this is a question of durability.

“Recently there’s been a push to use catalytic systems without , but the problem is that there hasn’t been a system proposed so far that simultaneously matches the catalytic activity and the durability of platinum,” Alamgir said.

The Georgia Tech researchers tried a different strategy. In the study, which was published on September 18 in the journal Advanced Functional Materialsand supported by the National Science Foundation, they describe creating several systems that used atomically-thin  of platinum supported by a layer of graphene—effectively maximizing the total surface area of the platinum available for catalytic reactions and using a much smaller amount of the precious metal.

Most platinum-based catalytic systems use nanoparticles of the metal chemically bonded to a support surface, where surface atoms of the particles do most of the catalytic work, and the catalytic potential of the atoms beneath the surface is never utilized as fully as the surface atoms, if at all.

This graphic shows how the graphene layer in gray provides structure and stability to the two atomic layers of platinum above represented in blue. Credit: Ji Il Choi

Additionally, the researchers showed that the new platinum films that are at least two atoms thick outperformed nanoparticle platinum in the dissociation energy, which is a measure of the energy cost of dislodging a surface platinum atom. That measurement suggests those films could make potentially longer-lasting catalytic systems.

To prepare the atomically-thin films, the researchers used a process called electrochemical atomic layer deposition to grow platinum monolayers on a layer of graphene, creating samples that had one, two or three atomic layers of atoms. The researchers then tested the samples for dissociation energy and compared the results to the energy of a single atom of platinum on graphene as well as the energy from a common configurations of platinum nanoparticles used in catalysts.

“The fundamental question at the heart of this work was whether it was possible that a combination of metallic and  can render the platinum atoms in a platinum-graphene combination more stable than their counterparts in bulk platinum used commonly in catalysts that are supported by metallic bonding,” said Seung Soon Jang, an associate professor in the School of Materials Science and Engineering.

The researchers found that the bond between neighboring platinum atoms in the film essentially combines forces with the bond between the film and the graphene layer to provide reinforcement across the system. That was especially true in the platinum film that was two atoms thick.

“Typically metallic films below a certain thickness are not stable because the bonds between them are not directional, and they tend to roll over each other and conglomerate to form a particle,” Alamgir said. “But that’s not true with graphene, which is stable in a two-dimensional form, even one atom thick, because it has very strong covalent directional bonds between its neighboring . So this new catalytic system could leverage the directional bonding of the graphene to support an atomically-thin film of platinum.”

Future research will involve further testing of how the films behave in a catalytic environment. The researchers found in earlier research on graphene-platinum films that the material behaves similarly in catalytic reactions regardless of which side—graphene or platinum—is the exposed active surface.

“In this configuration, the graphene is not acting as a separate entity from the platinum,” Alamgir said. “They’re working together as one. So we believe that if you’re exposing the  side, you get the same catalytic activity and you could further protect the platinum, potentially further enhancing durability.”

More information: Ji Il Choi et al, Contiguous and Atomically Thin Pt Film with Supra‐Bulk Behavior Through Graphene‐Imposed Epitaxy, Advanced Functional Materials(2019).  DOI: 10.1002/adfm.201902274

Journal information: Advanced Functional Materials

Provided by Georgia Institute of Technology

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Samsung set to ditch lithium ion batteries for graphene, and here’s why


Samsung phones will have super fast graphene, rather than lithium, batteries within the next two years.

According to leaker Evan Blass, Samsung is developing graphene batteries for its smartphones — and we could see the first ones arrive as soon as next year.

The reason for the change is clear: exceptionally fast charging. Reportedly a full charge will now take just half an hour on a graphene battery, and despite recent leaps forward in fast-charging that would still be a significant improvement on the standard lithium ion battery.

The news is the latest update we’ve heard since Samsung reported in 2017 that they had developed a graphene ball that could charge 5x faster than standard phone batteries (reported by Cnet). So why is it taking so long for the batteries to make it onto the market? Blass surmises that’s it’s simply a question of economics: “they still need to raise capacities while lowering costs.” Once that balance is found, this tech innovation could be a true game changer.

This news comes shortly after the release of Samsung’s latest flagship phablet, the Galaxy Note 10. It boasts an impressive 3500mAh battery, while it’s big brother — the Galaxy Note 10 Plus — has a whopping capacity of 4300mAh. But they’re not just about batteries. While both run on the powerful Exynos 9825 chip, specifications diverge significantly. The Galaxy note 10 has an 6.3-inch 1080 x 2280 resolution screen, with 8GB of RAM and a triple camera set-up; meanwhile, the Galaxy Note 10 Plus has an even larger 6.8-inch screen with a sharper 1440 x 3040 resolution, 12GB of RAM, and its triple rear camera is complemented with a Time of Flight 3D sensor.

With all the recent innovations in smartphone batteries, from huge capacities to Qi wireless charging, you might have thought there was nowhere else to innovate. But graphene technology could point towards an era of even faster charging. All that’s left to be seen is how pricey is it, and whether the capacity will be enough to satisfy demanding users.

Graphene Container System for Manufacturing


A graphene container system for manufacturing has been developed by GrapheneCA. The 40-foot containers are designed specifically for industrial producers and high-tech applications of graphene.

“It has developed a novel Mobile Graphene Container System (MGCS), the world’s first scalable, modular graphene production system, to help companies manufacture graphene in-house.
 
The New York-based company, which develops graphene-based technology for industries, said MGCS is available in 40-foot containers that are designed specifically for industrial producers and high-tech applications. The company said that with MGCS’ high quality, “ecologically clean graphene can be produced in-house” anywhere in the world.
 
“Think of Mobile Graphene Container System as your own graphene production line,” said David Robles, head of business development at GrapheneCA. “Producers will be able to secure a constant graphene supply and have greater control over their production volume and price.”
 
Robles said the process eliminates the reliance on “third-party suppliers and complicated logistics.”The industrial containers produce a high volume of industrial graphene in quantities of 4 tons of powder or more than 12 tons of graphene paste, said the company.
 
For high-tech applications, MGCS is able to produce pure graphene and graphene oxides derivatives, a much finer quality of product. The manufactured products have additional drying and quality-control features that reduce the need for graphene experts.
 
The company said that the next generation method simplifies graphene production and addresses problems that crop up during product shipments.
 
Graphene shipping is filled with complications due to the material being a highly voluminous compound, greatly limiting the amount of product that can be stored in a shipping container. MGCS allows for a clever work-around whereby ecologically clean graphene can be produced in-house by a company eliminating high shipping costs. Production only needs a water source and electric, diesel or bio-diesel power.”

 
Read full article GrapheneCA creates mobile graphene container system for in-house graphene manufacturing

Graphene-based ink may lead to printable energy storage devices


Top) The salt-templated process of synthesizing graphene nanosheets into ink. (Bottom) The ink and printed demonstration. Credit: Wei et al. ©2019 American Chemical Society

Researchers have created an ink made of graphene nanosheets, and demonstrated that the ink can be used to print 3-D structures. As the graphene-based ink can be mass-produced in an inexpensive and environmentally friendly manner, the new methods pave the way toward developing a wide variety of printable energy storage devices.

The researchers, led by Jingyu Sun and Zhongfan Liu at Soochow University and the Beijing Graphene Institute, and Ya-yun Li at Shenzhen University, have published a paper on their work in a recent issue of ACS Nano.

“Our work realizes the scalable and green synthesis of nitrogen-doped  nanosheets on a salt template by direct chemical vapor deposition,” Sun told Phys.org. “This allows us to further explore thus-derived inks in the field of printable energy storage.”

As the scientists explain, a key goal in graphene research is the mass production of graphene with high quality and at low cost. Energy-storage applications typically require graphene in powder form, but so far production methods have resulted in powders with a large number of structural defects and chemical impurities, as well as nonuniform layer thickness. This has made it difficult to prepare high-quality graphene inks.

In the new paper, the researchers have demonstrated a new method for preparing graphene inks that overcomes these challenges. The method involves growing nitrogen-doped graphene nanosheets over NaCl crystals using direct chemical vapor deposition, which causes molecular fragments of nitrogen and carbon to diffuse on the surface of the NaCl crystals. The researchers chose NaCl due to its natural abundance and low cost, as well as its water solubility.

To remove the NaCl, the coated crystals are submerged in water, which causes the NaCl to dissolve and leave behind pure nitrogen-doped graphene cages. In the final step, treating the cages with ultrasound transforms the cages into 2-D nanosheets, each about 5-7 graphite layers thick.

The resulting nitrogen-doped graphene nanosheets have relatively few defects and an ideal size (about 5 micrometers in side length) for printing, as larger flakes can block the nozzle.

To demonstrate the nanosheets’ effectiveness, the researchers printed a wide variety of 3-D structures using inks based on the graphene sheets.

Among their demonstrations, the researchers used the ink as a conductive additive for an  (vanadium nitride) and used the composite ink to print flexible electrodes for supercapacitors with high power density and good cyclic stability. 

In a second demonstration, the researchers created a composite ink made of the graphene sheets along with binder material (polypropylene) for printing interlayers for Li−S batteries.

Compared to batteries with separators made only of the conventional material, those made with the composite material exhibited enhanced conductivity, leading to an overall improvement in battery performance.

“In the future, we plan to exploit the direct technique for the mass production of high-quality graphene powders toward emerging printable energy storage applications,” Sun said.

More information: Nan Wei et al. “Scalable Salt-Templated Synthesis of Nitrogen-Doped Graphene Nanosheets toward Printable Energy Storage.” ACS Nano. DOI: 10.1021/acsnano.9b03157

Journal information: ACS Nano

Graphene Nanocomposite Foam Material Harvests Water from Air


water-cycle (1).png

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

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

 

Read/ Watch More …

Genesis Nanotech – Watch a Presentation Video on Our Current Project

Nano Enabled Batteries and Super Capacitors

Tenka Energy, Inc. Building Ultra-Thin Energy Dense SuperCaps and NexGen Nano-Enabled Pouch & Cylindrical Batteries – Energy Storage Made Small and POWERFUL!

 

 

 

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.


Explore further

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