Graphene-MoS2 Hybrid Material for Energy Storage and Transfer Applications



The exponential growth rates of population density and the worldwide economy has required a significant investment in energy storage devices, particularly those which are portable and can be used for future flexible electronics.

To meet the increasing energy demands of a growing population, not only are new ways of creating the energy being devised, but so are new ways of storing this that energy. 

A team of Researchers from India have developed a hybrid nanomaterial composed of graphene and flower-shaped MoS2 nanostructures to store energy in a prototype supercapacitor.



As a result of an ever-expanding population and its associated energy consumption, there is a projection that the demand for energy in 2050 will exceed 40 terawatts (TW). 




Because of the requirements for a high amount of energy, new ways of producing renewable energy are being researched and implemented, as current non-renewable fuels will eventually run out.

Due to both the energy increase and nature of the produced energy, new materials are also being developed that can store this energy efficiently.

At present, such storage capabilities are not even close to meeting the energy demands set out in future predictions. Current devices can only store 1% of renewable energy that storage devices do for fossil fuels.

As such, there is a great need to not only create materials which can store renewable energy, but to also produce materials with a real-world function that can rival non-renewable storage options, potentially as a variant of Li-ion and Na-air batteries that can hold renewable-produced energy.



The team of Researchers have created a hybrid nanomaterial composed of flower-like MoS2 nanostructures and 3D graphene heterostructures to be used as an active material in energy storage and transfer devices.
 

The Researchers also tested and employed the material in a solid-state supercapacitor, where the 3D graphene-MoS2 material was used with a graphite current collector.

To create the active material, the Researchers first created MoS2 nanospheres through a hydrothermal method using ammonium molybdate and thiourea. 

A modified hydrothermal method was then utilized to deposit 3D graphene oxide onto a graphite electrode using a series of wet synthetic steps.

The MoS2 nanostructures were then also deposited onto the graphene sheets. To create the supercapacitor, the Researchers, alongside the electrodes, used a polyvinyl acetate (PVA) gel and a gel-soaked whatman filter paper as part of the internal components. A drying time of 12 hours was required for the device to be fully fabricated.

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Graphene and other carbon Nanomaterials can Replace Scarce Metals


Graphene Scarce Metals 170919091029_1_540x360

Scarce metals are found in a wide range of everyday objects around us. They are complicated to extract, difficult to recycle and so rare that several of them have become “conflict minerals” which can promote conflicts and oppression. New research shows that there are potential technology-based solutions that can replace many of the metals with carbon nanomaterials, such as graphene.

Scarce metals are found in a wide range of everyday objects around us. They are complicated to extract, difficult to recycle and so rare that several of them have become “conflict minerals” which can promote conflicts and oppression. A survey at Chalmers University of Technology now shows that there are potential technology-based solutions that can replace many of the metals with carbon nanomaterials, such as graphene.

They can be found in your computer, in your mobile phone, in almost all other electronic equipment and in many of the plastics around you. Society is highly dependent on scarce metals, and this dependence has many disadvantages.

Scarce metals such as tin, silver, tungsten and indium are both rare and difficult to extract since the workable concentrations are very small. This ensures the metals are highly sought after — and their extraction is a breeding ground for conflicts, such as in the Democratic Republic of the Congo where they fund armed conflicts.

In addition, they are difficult to recycle profitably since they are often present in small quantities in various components such as electronics.

Rickard Arvidsson and Björn Sandén, researchers in environmental systems analysis at Chalmers University of Technology, have now examined an alternative solution: substituting carbon nanomaterials for the scarce metals. These substances — the best known of which is graphene — are strong materials with good conductivity, like scarce metals.

“Now technology development has allowed us to make greater use of the common element carbon,” says Sandén. “Today there are many new carbon nanomaterials with similar properties to metals. It’s a welcome new track, and it’s important to invest in both the recycling and substitution of scarce metals from now on.”

The Chalmers researchers have studied the main applications of 14 different metals, and by reviewing patents and scientific literature have investigated the potential for replacing them by carbon nanomaterials. The results provide a unique overview of research and technology development in the field.

According to Arvidsson and Sandén the summary shows that a shift away from the use of scarce metals to carbon nanomaterials is already taking place.

“There are potential technology-based solutions for replacing 13 out of the 14 metals by carbon nanomaterials in their most common applications. The technology development is at different stages for different metals and applications, but in some cases such as indium and gallium, the results are very promising,” Arvidsson says.

“This offers hope,” says Sandén. “In the debate on resource constraints, circular economy and society’s handling of materials, the focus has long been on recycling and reuse. Substitution is a potential alternative that has not been explored to the same extent and as the resource issues become more pressing, we now have more tools to work with.”

The research findings were recently published in the Journal of Cleaner Production. Arvidsson and Sandén stress that there are significant potential benefits from reducing the use of scarce metals, and they hope to be able to strengthen the case for more research and development in the field.

“Imagine being able to replace scarce metals with carbon,” Sandén says. “Extracting the carbon from biomass would create a natural cycle.”

“Since carbon is such a common and readily available material, it would also be possible to reduce the conflicts and geopolitical problems associated with these metals,” Arvidsson says.

At the same time they point out that more research is needed in the field in order to deal with any new problems that may arise if the scarce metals are replaced.

“Carbon nanomaterials are only a relatively recent discovery, and so far knowledge is limited about their environmental impact from a life-cycle perspective. But generally there seems to be a potential for a low environmental impact,” Arvidsson says.

Facts:

Carbon nanomaterials consist solely or mainly of carbon, and are strong materials with good conductivity. Several scarce metals have similar properties. The metals are found, for example, in cables, thin screens, flame-retardants, corrosion protection and capacitors.

Rickard Arvidsson and Björn Sandén at Chalmers University of Technology have investigated whether the carbon nanomaterials graphene, fullerenes and carbon nanotubes have the potential to replace 14 scarce metals in their main areas of application (see table in attached image). They found potential technology-based solutions to replace the metals with carbon nanomaterials for all applications except for gold in jewellery. The metals which we are closest to being able to substitute are indium, gallium, beryllium and silver.

Story Source:

Materials provided by Chalmers University of TechnologyNote: Content may be edited for style and length.


Journal Reference:

  1. Rickard Arvidsson, Björn A. Sandén. Carbon nanomaterials as potential substitutes for scarce metalsJournal of Cleaner Production, 2017; 156: 253 DOI: 10.1016/j.jclepro.2017.04.048

Graphene-wrapped nanocrystals may open door toward next-gen fuel cells



Ultra-Thin  oxide layer (oxygen atoms shown in red) coating graphene-wrapped magnesium nanoparticles (orange) still allows in hydrogen atoms (blue) for hydrogen storage applications

Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory have developed a mix of metal nanocrystals wrapped in graphene that may open the door to the creation of a new type of fuel cell by enabling enhanced hydrogen storage properties.

Graphene-Wrapped Nanocrystals Make Inroads Toward Next-Gen Fuel Cells



Ultra-thin oxide layer (oxygen atoms shown in red) coating graphene-wrapped magnesium nanoparticles (orange) still allows in hydrogen atoms (blue) for hydrogen storage applications

The team studied how graphene can be used as both selective shielding, as well as a performance increasing factor in terms of hydrogen storage. 

The study drew upon a range of Lab expertise and capabilities to synthesize and coat the magnesium crystals, which measure only 3-4 nanometers (billionths of a meter) across; study their nanoscale chemical composition with X-rays; and develop computer simulations and supporting theories to better understand how the crystals and their carbon coating function together.

Reduced graphene oxide (or rGO) has nanoscale holes that permit hydrogen to pass through while keeping larger molecules away. This carbon wrapping was intended to prevent the magnesium – which is used as a hydrogen storage material – from reacting with its environment, including oxygen, water vapor and carbon dioxide. 

Such exposures could produce a thick coating of oxidation that would prevent the incoming hydrogen from accessing the magnesium surfaces. 

The study, however, suggests that an atomically thin layer of oxidation did form on the crystals during their preparation. Surprisingly, this oxide layer doesn’t seem to degrade the material’s performance.

The study’s lead author stated “Most people would suspect that the oxide layer is bad news for hydrogen storage, which it turns out may not be true in this case. Without this oxide layer, the reduced graphene oxide would have a fairly weak interaction with the magnesium, but with the oxide layer the carbon-magnesium binding seems to be stronger. 

That’s a benefit that ultimately enhances the protection provided by the carbon coating. There doesn’t seem to be any downside”.

The researchers noted that the current generation of hydrogen-fueled vehicles power their fuel cell engines using compressed hydrogen gas. “This requires bulky, heavy cylindrical tanks that limit the driving efficiency of such cars”, and the nanocrystals offer one possibility for eliminating these bulky tanks by storing hydrogen within other materials.

Ionic Industries announces a process for economically mass-producing graphene micro supercapacitors



Ionic Industries recently announced a process for economically mass-producing graphene micro supercapacitors and added that its directors and key personnel have taken direct stakes in the company.

Ionic Industries’ graphene supercapacitors patent image




Ionic stated that since it published the positive results on its graphene micro planar supercapacitors 2 years before, the company has been working toward developing a device that not only demonstrates similar performance but can be produced at scale to deliver an economically viable device.

The last 2 years of work reportedly culminated in the filing of a new patent titled: Capacitive energy storage device and method of producing same (Australian Provisional Patent Application 2017903619). 

The new patent covers: the design of new energy storage device, being a planar micro supercapacitor printed on a porous film; Ionic’s technique of stacking multiple layers of planar supercapacitors to create a 3D device that has ground-breaking energy and power density characteristics; and, most importantly, the company’s method for printing these devices so that they can be mass produced at low cost.

The critical element in this new technology is the ability to print the supercapacitors in the 1000s per minute, rather than individually creating each device with an expensive, direct-write approaches using lasers or ion beams. The technology builds on Ionic’s existing patent relating to graphene oxide membranes and it means the company could create these devices as easily as factories today produce food packaging and labels using gravure printers.

The team is now working on assembling the prototype device which is scheduled for completion in the next 6 weeks before it go into trials for a period of several months. 
The expected end result is a supercapacitor energy storage device comprised of printed graphene micro planar supercapacitors that can be produced economically at scale.

Ionic stated that it is extremely excited about this development as it brings it well within sight of a commercial product. The next steps involve identifying appropriate, world leading partners with whom Ionic can introduce this technology into products such as medical devices, wearable technologies, IoT devices or remote sensing applications.

Toward a smart graphene membrane to desalinate water: Penn State University


Graphene H2O towardasmartA scalable graphene-based membrane for producing clean water Credit: Aaron Morelos-Gomez. Credit: Pennsylvania State University

An international team of researchers, including scientists from Shinshu University (Japan) and the director of Penn State’s ATOMIC Center, has developed a graphene-based coating for desalination membranes that is more robust and scalable than current nanofiltration membrane technologies. The result could be a sturdy and practical membrane for clean water solutions as well as protein separation, wastewater treatment and pharmaceutical and food industry applications.

“Our dream is to create a smart  that combines high flow rates, high efficiency, long lifetime, self-healing and eliminates bio and inorganic fouling in order to provide clean water solutions for the many parts of the world where clean water is scarce,” says Mauricio Terrones, professor of physics, chemistry and materials science and engineering, Penn State. “This work is taking us in that direction.”

The hybrid membrane the team developed uses a simple spray-on technology to coat a mixture of graphene oxide and few-layered graphene in solution onto a backbone support membrane of polysulfone modified with polyvinyl alcohol. The support membrane increased the robustness of the hybrid membrane, which was able to stand up to intense cross-flow, high pressure and chlorine exposure. Even in early stages of development, the membrane rejects 85 percent of salt, adequate for agricultural purposes though not for drinking, and 96 percent of dye molecules. Highly polluting dyes from textile manufacturing is commonly discharged into rivers in some areas of the world.

Chlorine is generally used to mitigate biofouling in membranes, but chlorine rapidly degrades the performance of current polymer membranes. The addition of few-layer graphene makes the new membrane highly resistant to chlorine.

Graphene is known to have high mechanical strength, and porous graphene is predicted to have 100 percent salt rejection, making it a potentially ideal material for desalination membranes. However, there are many challenges with scaling up graphene to industrial quantities including controlling defects and the need for complex transfer techniques required to handle the two-dimensional material. The current work attempts to overcome the scalability issues and provide an inexpensive, high quality membrane at manufacturing scale.

The work was performed in the Global Aqua Innovation Center and the Institute of Carbon Science and Technology at Shinshu University, Nagano, Japan, where Terrones is also a Distinguished Invited Professor. The team includes researchers Aaron Morelos-Gomez, Josue Ortiz-Medina and Rodolfo Cruz-Silva, former Ph.D. students of Terrones. Morelos-Gomez is lead author on a paper published online on August 28 in Nature Nanotechnology describing their work titled “Effective NaCL and dye rejection of hybrid graphene oxide/graphene layered membranes.” The Japanese researchers, Hiroyuki Muramatsu, Takumi Araki, Tomoyuki Fukuyo, Syogo Tejima, Kenji Takeuchi, and Takuya Hayashi, were also led by Professor Morinobu Endo.

First author Aaron Morelos-Gomez says, “Our membrane overcomes the water solubility of graphene oxide by using polyvinyl alcohol as an adhesive making it resistant against strong water flow and high pressures. By mixing  with  we could also improve significantly its chemical resistance.”

Professor Morinobu Endo concludes that “this is the first step towards more effective and smart membranes that could self-adapt depending on their environment.”

 Explore further: Graphene sieve turns seawater into drinking water

More information: Aaron Morelos-Gomez et al. Effective NaCl and dye rejection of hybrid graphene oxide/graphene layered membranes, Nature Nanotechnology (2017). DOI: 10.1038/nnano.2017.160

Read more at: https://phys.org/news/2017-09-smart-graphene-membrane-desalinate.html#jCp

Read more at: https://phys.org/news/2017-09-smart-graphene-membrane-desalinate.html#jCp

We May Finally Have a Way to Cheaply Manufacture Pure Graphene


Synthesizing Pure Graphene




Researchers have been singing the praises of graphene ever since it was first isolated from graphite back in 2004. That’s not terribly surprising given the unique properties the two-dimensional material possesses. Graphene has since proven useful for everything from superconductors to microchips to tougher-than-steel rubber bands, but despite the wealth of research, manufacturing graphene for large-scale commercial use has remained problematic — the process is simply too costly and complicated.

University of Connecticut chemistry professor Doug Adamson might be able to change that. He and his colleagues have figured out a cost-effective way to synthesize this wonder material, and perhaps best of all, Adamson claims his method synthesizes graphene in its pure, unoxidized form. The research has been published in ACS Nano.

Watch More: Super Materials of Tomorrow – Graphene

Adamson’s method takes advantage of one of graphene’s typically undesirable characteristics: its insolubility to most solvents. After placing graphite in an interface of water and oil, the material spreads spontaneously to cover the interface. There, it becomes trapped in individual, overlapping graphene sheets that can be locked in place using plastic or other cross-linked polymers.

“The innovation and technology behind our material is our ability to use a thermodynamically driven approach to un-stack graphite into its constituent graphene sheets, and then arrange those sheets into a continuous, electrically conductive, three-dimensional structure,” Adamson explained in a UConn press release.


Its Best Behavior

The “graphene” most researchers use in their studies is an oxidized version of the material. Adding oxygen to graphene makes it easier to work with, but it also increases the cost, requires the use of hazardous materials, and adds time to the manufacturing process. It also reduces graphene’s mechanical, thermal, and electrical properties — essentially what makes graphene great.

“The simplicity of our approach is in stark contrast to current techniques used to exfoliate graphite that rely on aggressive oxidation or high-energy mixing or sonication — the application of sound energy to separate particles — for extended periods of time,” Adamson said. “As straightforward as our process is, no one else had reported it. We proved it works.”

Now that Adamson’s team has found a way to produce this pristine graphene, they’re looking forward to potential applications. One of those is desalination. The group created a startup, 2D Material Technologies, that is working on a device that uses their pure graphene and a process known as capacitive deionization (CDI) to remove salt from brackish water.

While much has already been accomplished using graphene, a technique like Adamson’s that can easily be scaled up for the mass production of the material could lead to an explosion of new research and commercial applications. A bit more than a decade after its discovery, all the wonder of graphene could finally be taken advantage of in a meaningful way.

The Design of Future Nano-Electronic  Circuits – Free Flowing Electrons in Graphene 



Electrons flowing like liquid in graphene start a new wave of physics – University of Manchester 

A new understanding of the physics of conductive materials has been uncovered by scientists observing the unusual movement of electrons in graphene.

Graphene is many times more conductive than copper thanks, in part, to its two-dimensional structure. In most metals, conductivity is limited by crystal imperfections which cause electrons to frequently scatter like billiard balls when they move through the material.


Now, observations in experiments at the National Graphene Institute have provided essential understanding as to the peculiar behaviour of electron flows in graphene, which need to be considered in the design of future nanoelectronic circuits.

In some high-quality materials, like graphene, electrons can travel micron distances without scattering, improving the conductivity by orders of magnitude. This so-called ballistic regime, imposes the maximum possible conductance for any normal metal, which is defined by the Landauer-Buttiker formalism.

Appearing today in Nature Physics (“Superballistic flow of viscous electron fluid through graphene constrictions”), researchers at The University of Manchester, in collaboration with theoretical physicists led by Professor Marco Polini and Professor Leonid Levitov, show that Landauer’s fundamental limit can be breached in graphene. Even more fascinating is the mechanism responsible for this.

Last year, a new field in solid-state physics termed ‘electron hydrodynamics’ generated huge scientific interest. Three different experiments, including one performed by The University of Manchester, demonstrated that at certain temperatures, electrons collide with each other so frequently they start to flow collectively like a viscous fluid.

The new research demonstrates that this viscous fluid is even more conductive than ballistic electrons. 

The result is rather counter-intuitive, since typically scattering events act to lower the conductivity of a material, because they inhibit movement within the crystal. However, when electrons collide with each other, they start working together and ease current flow.

This happens because some electrons remain near the crystal edges, where momentum dissipation is highest, and move rather slowly. At the same time, they protect neighbouring electrons from colliding with those regions. Consequently, some electrons become super-ballistic as they are guided through the channel by their friends.

Sir Andre Geim said: “We know from school that additional disorder always creates extra electrical resistance. In our case, disorder induced by electron scattering actually reduces rather than increase resistance. This is unique and quite counterintuitive: Electrons when make up a liquid start propagating faster than if they were free, like in vacuum”.

The researchers measured the resistance of graphene constrictions, and found it decreases upon increasing temperature, in contrast to the usual metallic behaviour expected for doped graphene.

By studying how the resistance across the constrictions changes with temperature, the scientists revealed a new physical quantity which they called the viscous conductance. The measurements allowed them to determine electron viscosity to such a high precision that the extracted values showed remarkable quantitative agreement with theory.


Source: University of Manchester

Army COE Creates New Energy Efficient ‘Graphene Oxide’ Water Filter at Commercial Scale



The Army Corps of Engineers have successfully created a usable prototype of a new type of water filter.

The membranes are made of a mixture of chitosan, a material commonly found in shrimp shells, and a new synthetic chemical known as “graphene oxide”. Graphene oxide is a highly researched chemical worldwide.

  According to the Army Corps, one problem encountered by scientists working with graphene oxide is not being able to synthesize the material on a scale that can be put to use.

“One of the major breakthroughs that we’ve had here is that with our casting process, we’re not limited by size,” explains Luke Gurtowski, a research chemical engineer working on the membranes.


These filters have been found to effectively remove a number of different contaminants commonly found in water.

Dr. Christopher Griggs is the research scientist in charge of overseeing development of the new membranes.

Dr. Griggs told us, “Anybody who’s experienced water shortages or has been concerned about their water quality, or any type of contaminants in the water, this type of technology certainly works to address that.”

Another challenged faced by conventional water filtering methods is maintaining high energy efficiency.

“It requires a lot of energy for the net driving pressure to force the water through the membrane,” Dr. Griggs explains. “…we’re going to have to look to new materials to try to get those efficiency gains, and so graphene oxide is a very promising candidate for that.”

The Engineer Research and Development Center currently has two patents associated with the new filters and hopes to apply them for both civil and military purposes in the near future. 

Flexible Batteries Power the Future of Wearable Technology: U of Manchester


flexiblebattCredit: University of Manchester

The rapid development of wearable technology has received another boost from a new development using graphene for printed electronic devices.

New research from The University of Manchester has demonstrated flexible battery-like devices printed directly on to textiles using a simple screen-printing technique.

The current hurdle with wearable technology is how to power devices without the need for cumbersome battery packs. Devices known as supercapacitors are one way to achieve this. A  acts similarly to a battery but allows for rapid charging which can fully charge devices in seconds.

Now a solid-state flexible supercapacitor device has been demonstrated by using conductive -oxide ink to print onto cotton fabric. As reported in the journal 2-D Materials the printed electrodes exhibited excellent mechanical stability due to the strong interaction between the ink and textile substrate. Graphene-Ribbon-Developing-Flexible-Li-Ion-Battery

Further development of graphene-oxide printed supercapacitors could turn the vast potential of  into the norm. High-performance sportswear that monitors performance, embedded health-monitoring devices, lightweight military gear, new classes of  and even wearable computers are just some of the applications that could become available following further research and development.

To power these new wearable devices, the energy storage system must have reasonable mechanical flexibility in addition to high energy and power density, good operational safety, long cycling life and be low cost.

 Credit: University of Manchester

Dr Nazmul Karim, Knowledge Exchange Fellow, the National Graphene Institute and co-author of the paper said: “The development of graphene-based flexible textile supercapacitor using a simple and scalable printing technique is a significant step towards realising multifunctional next generation wearable e-textiles.”

“It will open up possibilities of making an environmental friendly and cost-effective smart e-textile that can store energy and monitor human activity and physiological condition at the same time”.

Graphene-oxide is a form of graphene which can be produced relatively cheaply in an ink-like solution. This solution can be applied to textiles to create supercapacitors which become part of the fabric itself.

Kaust wearablebattery1Dr Amor Abdelkader, also co-author of the paper said: “Textiles are some of the most flexible substrates, and for the first time, we printed a stable device that can store energy and be as flexible as cotton.

“The  is also washable, which makes it practically possible to use it for the future smart clothes. We believe this work will open the door for printing other types of devices on  using 2-D-materials inks.”

The University of Manchester is currently completing the construction of its second major graphene facility to complement the National Graphene Institute (NGI). Set to be completed 2018, the £60m Graphene Engineering Innovation Centre (GEIC) will be an international research and technology facility.

The GEIC will offer the UK the unique opportunity to establish a leading role in graphene and related two-dimensional materials. The GEIC will be primarily industry-led and focus on pilot production and characterisation.

 Explore further: Researchers develop simple way to fabricate micro-supercapacitors with high energy density

 

 

MIT team creates flexible, transparent solar cells with graphene electrodes



Researchers at the Massachusetts Institute of Technology (MIT) have developed flexible and transparent graphene-based solar cells, which can be mounted on various surfaces ranging from glass to plastic to paper and tape. The graphene devices exhibited optical transmittance of 61% across the whole visible regime and up to 69% at 550 nanometers. The power conversion efficiency of the graphene solar cells ranged from 2.8% to 4.1%.

MIT team’s flexible, transparent solar cell with graphene electrodes image

A common challenge in making transparent solar cells with graphene is getting the two electrodes to stick together and to the substrate, as well as ensuring that electrons only flow out of one of the graphene layers. Using heat or glue can damage the material and reduce its conductivity, so the MIT team developed a new technique to tackle this issue. Rather than applying an adhesive between the graphene and the substrate, they sprayed a thin layer of ethylene-vinyl acetate (EVA) over the top, sticking them together like tape instead of glue.

The MIT team compared their graphene electrode solar cells against others made from standard materials like aluminum and indium tin oxide (ITO), built on rigid glass and flexible substrates. The power conversion efficiency (PCE) of the graphene solar cells was far lower than regular solar panels, but much better than previous transparent solar cells. This is a positive advancement, obviously.
Samples of solar cells using electrodes of different materials for testing image


Efficiency is often a trade-off from the graphene solar cells being flexible and transparent. In that regard the cells performed well, transmitting almost 70% of the light in the middle of the human range of vision. Hopefully the numbers will continue to improve. According to the researchers’ calculations, the efficiency of these graphene solar cells could be pushed as high as 10% without losing any transparency, and doing just that is the next step in the project. The researchers are also working on ways to scale up the system to cover windows and walls.
Source:  newatlas