#Aligned carbon nanotube/graphene sandwiches By in situ nitrogen doping and structural hybridization of carbon nanotubes (CNTS) and graphene via a two-step chemical vapor deposition (CVD) scientists have fabricated nitrogen-doped aligned carbon nanotube/graphene (N-ACNT/G) sandwiches
with three-dimensional (3d) electron transfer pathways interconnected ion diffusion channels and enhanced interfacial affinity and activity.
CNTS and graphene the most highlighted sp2-bonded carbon nanomaterials over the past decades have attracted enormous attention in the area of energy storage heterogeneous catalysis healthcare environmental protection as well as nanocomposites
The combination of CNTS and graphene into 3d hybrid composites can usually mitigate the self-aggregation
Up to now several strategies have been explored to fabricate such CNTS/graphene hybrids including post-organization methods and in situ growth while integration of high-quality CNTS and graphene without barrier layers is still difficult.
A team from Tsinghua University (China) led by Prof. Qiang Zhang and Fei Wei have fabricated now successfully sandwich-like N-ACNT/G hybrids via a two-step catalytic growth on bifunctional natural materials.
and graphene was deposited sequentially onto the surface of lamellar flakes at the bottom of aligned CNTS through a high-temperature (H-T) CVD.
After catalyst removal alternative aligned CNTS and graphene were connected vertically to each other in long-range periodicity thereby forming a sandwich-like structure.
and graphene were grown on the NPS and lamellar flakes at L -and H-T CVD respectively and conjointly. first-author Cheng Tang explained to Phys.
Org''Thereby the seamless connection of high-quality aligned CNTS and graphene provided 3d electron transfer pathways and interconnected ion diffusion channels.
and graphene provides rapid electron transfer and mechanical robustness. The 3d interconnected mesoporous space improves the penetration and diffusion of electrolytes.
Rational hybridization of N-doped graphene/carbon nanotubes for oxygen reduction and oxygen evolution reaction More information:
/Graphene Sandwiches: Facile Catalytic Growth on Bifunctional Natural Catalysts and Their Applications as Scaffolds for High-Rate Lithium-Sulfur Batteries.
#Molecular self-assembly controls graphene-edge configuration A research team headed by Prof. Patrick Han and Prof.
Taro Hitosugi at the Advanced Institute of Materials Research (AIMR), Tohoku University discovered a new bottom-up fabrication method that produces defect-free graphene nanoribbons (GNRS) with periodic zigzag-edge regions.
and length distribution, is a stepping stone towards future graphene device fabrication by self-assembly. Graphene, with its low dimensionality, high stability, high strength,
and high charge-carrier mobility, promises to be a revolutionary material for making next-generation high-speed transistors.
graphene's properties are predicted to be directly controllable by its structure. For example, recent works have demonstrated that the bandgap of armchair GNRS is controlled by the ribbon width.
These features could be exploited for making single graphene interconnections between prefabricated structures by self-assembly."
"Our method opens the possibility for self-assembling single graphene devices at desired locations, because of the length and of the direction control. t
#Engineers advance understanding of graphene's friction properties (Phys. org) An interdisciplinary team of engineers from the University of Pennsylvania has made a discovery regarding the surface properties of graphene the Nobel-prize winning material that consists of an atomically thin sheet
However on the nanoscale adding fluorine to graphene had been reported to vastly increase the friction experienced
Besides its applications in circuitry and sensors graphene is of interest as a super-strong coating.
Because graphene is so strong thin and smooth one of its potential applications is to reduce friction and increase the lifespan of these devices.
We wanted to better understand the fundamental mechanisms of how the addition of other atoms influences the friction of graphene.
The addition of fluorine atoms to graphene's carbon lattice makes for an intriguing combination
so we thought fluorinated graphene might be like two-dimensional Teflon. To test the friction properties of this material the Penn researchers collaborated with Paul Sheehan and Jeremy Robinson of the Naval Research Laboratory.
Sheehan and Robinson were the first to discover fluorinated graphene and are experts in producing samples of the material to specification.
This meant we were able to systematically vary the degree of fluorination in our graphene samples
The researchers were surprised to find that adding fluorine to graphene increased the material's friction
they also showed that the addition of fluorine increased the stiffness of the graphene samples and hypothesized this was increased responsible for the friction.
whose expertise is in developing atomic scale simulations of mechanical action to help explain what the addition of the fluorine was doing to the graphene's surface.
It turns out that by adding fluorine Liu said we're changing the energy corrugation landscape of the graphene.
In fluorinated graphene the fluorine atoms do stick up out of the plane of carbon atoms but the physical changes in height paled in comparison to the changes of local energy each fluorine atom produced.
and deep valleys in between them compared to the smooth plane of regular graphene. You could say it's like trying slide over a smooth road versus a bumpy road.
Beyond the implication for graphene's coating applications the team's findings provide fundamental insight into graphene's surface properties.
Seeing that fluorine increases friction in graphene isn't necessarily a bad thing since it may give us a way to tailor that property to a given application.
On the edge of graphene More information: Fluorination of Graphene Enhances Friction Due to Increased Corrugation.
Qunyang Li Xin-Z. Liu Sang-Pil Kim Vivek B. Shenoy Paul E. Sheehan Jeremy T. Robinson and Robert W. Carpick.
#Doped graphene nanoribbons with potential Graphene is a semiconductor when prepared as an ultra-narrow ribbon although the material is actually a conductive material.
Researchers from Empa and the Max Planck Institute for Polymer Research have developed now a new method to selectively dope graphene molecules with nitrogen atoms.
and undoped graphene pieces they were able to form heterojunctions in the nanoribbons thereby fulfilling a basic requirement for electronic current to flow in only one direction
when voltage is applied the first step towards a graphene transistor. Furthermore the team has managed successfully to remove graphene nanoribbons from the gold substrate on
which they were grown and to transfer them onto a nonconductive material. Graphene possesses many outstanding properties it conducts heat
and electricity it is transparent harder than diamond and extremely strong. But in order to use it to construct electronic switches a material must not only be an outstanding conductor it should also be switchable between on and off states.
The problem however is that the bandgap in graphene is extremely small. Empa researchers from the nanotech@surfaces laboratory thus developed a method some time ago to synthesise a form of graphene with larger bandgaps by allowing ultra-narrow graphene nanoribbons to grow via molecular self-assembly.
Graphene nanoribbons made of differently doped segmentsthe researchers led by Roman Fasel have achieved now a new milestone by allowing graphene nanoribbons consisting of differently doped subsegments to grow.
Instead of always using the same pure carbon molecules they used additionally doped molecules molecules provided with foreign atoms in precisely defined positions in this case nitrogen.
The researchers describe the corresponding heterojunctions in segmented graphene nanoribbons in the recently published issue of Nature Nanotechnology.
Transferring graphene nanoribbons onto other substratesin addition the scientists have solved another key issue for the integration of graphene nanotechnology into conventional semiconductor industry:
how to transfer the ultra-narrow graphene ribbons onto another surface? As long as the graphene nanoribbons remain on a metal substrate (such as gold used here) they cannot be used as electronic switches.
Gold conducts and thus creates a short-circuit that sabotages the appealing semiconducting properties of the graphene ribbon.
Fasel's team and colleagues at the Max-Planck-Institute for Polymer Research in Mainz have succeeded in showing that graphene nanoribbons can be transferred efficiently
and intact using a relatively simple etching and cleaning process onto (virtually) any substrate for example onto sapphire calcium fluoride or silicon oxide.
Graphene is thus increasingly emerging as an interesting semiconductor material and a welcome addition to the omnipresent silicon.
The semiconducting graphene nanoribbons are particularly attractive as they allow smaller and thus more energy efficient and faster electronic components than silicon.
However the generalized use of graphene nanoribbons in the electronics sector is anticipated not in the near future due in part to scaling issues
Fasel estimates that it may still take about 10 to 15 years before the first electronic switch made of graphene nanoribbons can be used in a product.
Graphene nanoribbons for photovoltaic componentsphotovoltaic components could also one day be based on graphene. In a second paper published in Nature Communications Pascal Ruffieux also from the Empa nanotech@surfaces laboratory
and his colleagues describe a possible use of graphene strips for instance in solar cells. Ruffieux and his team have noticed that particularly narrow graphene nanoribbons absorb visible light exceptionally well
and are therefore highly suitable for use as the absorber layer in organic solar cells. Compared to normal graphene
which absorbs light equally at all wavelengths the light absorption in graphene nanoribbons can be increased enormously in a controlled way
whereby researchers set the width of the graphene nanoribbons with atomic precision n
#Rethinking basic science of graphene synthesis shows route to industrial-scale production A new route to making graphene has been discovered that could make the 21st century's wonder material easier to ramp up to industrial scale.
Graphene tightly bound single layer of carbon atoms with super strength and the ability to conduct heat
and electricity better than any other known materialas potential industrial uses that include flexible electronic displays, high-speed computing, stronger wind turbine blades,
and more-efficient solar cells, to name just a few under development. In the decade since Nobel laureates Konstantin Novoselov and Andre Geim proved the remarkable electronic and mechanical properties of graphene
researchers have been hard at work to develop methods of producing pristine samples of the material on a scale with industrial potential.
Now, a team of Penn State scientists has discovered a route to making single-layer graphene that has been overlooked for more than 150 years."
"There are lots of layered materials similar to graphene with interesting properties, but until now we didn't know how to chemically pull the solids apart to make single sheets without damaging the layers,
and graphene could apply to many other layered materials of interest to researchers in the Penn State Center for Two-dimensional and Layered Materials who are investigating
what are referred to as"Materials Beyond Graphene.""The next step for Mallouk and colleagues will be to figure out how to speed the reaction up
Using the special properties of graphene a two-dimensional form of carbon that is only one atom thick a prototype detector is able to see an extraordinarily broad band of wavelengths.
and colleagues at the U s. Naval Research Lab and Monash University Australia gets around these problems by using graphene a single layer of interconnected carbon atoms.
By utilizing the special properties of graphene the research team has been able to increase the speed
Graphene a sheet of pure carbon only one atom thick is suited uniquely to use in a terahertz detector
because when light is absorbed by the electrons suspended in the honeycomb lattice of the graphene they do not lose their heat to the lattice
Light is absorbed by the electrons in graphene which heat up but don't lose their energy easily.
These heated electrons escape the graphene through electrical leads much like steam escaping a tea kettle.
Sensitive Room-temperature Terahertz Detection via Photothermoelectric Effect in Graphene Xinghan Cai et al. Nature Nanotechnology dx. doi. org/10.1038/nnano. 2014.18
#First graphene-based flexible display produced A flexible display incorporating graphene in its pixels'electronics has been demonstrated successfully by the Cambridge Graphene Centre and Plastic Logic,
the first time graphene has been used in a transistor-based flexible device. The partnership between the two organisations combines the graphene expertise of the Cambridge Graphene Centre (CGC),
with the transistor and display processing steps that Plastic Logic has developed already for flexible electronics.
This prototype is a first example of how the partnership will accelerate the commercial development of graphene,
and is a first step towards the wider implementation of graphene and graphene-like materials into flexible electronics.
Graphene is a two-dimensional material made up of sheets of carbon atoms. It is among the strongest most lightweight and flexible materials known,
or backplane, of this display includes a solution-processed graphene electrode, which replaces the sputtered metal electrode layer within Plastic Logic's conventional devices,
Graphene is more flexible than conventional ceramic alternatives like indium-tin oxide (ITO) and more transparent than metal films.
The ultra-flexible graphene layer may enable a wide range of products including foldable electronics. Graphene can also be processed from solution bringing inherent benefits of using more efficient printed
and roll-to-roll manufacturing approaches. The new 150 pixel per inch (150 ppi) backplane was made at low temperatures (less than 100°C) using Plastic Logic's Organic Thin Film Transistor (OTFT) technology.
The graphene electrode was deposited from solution and subsequently patterned with micron-scale features to complete the backplane.
"We are happy to see our collaboration with Plastic Logic resulting in the first graphene-based electrophoretic display exploiting graphene in its pixels'electronics,
"said Professor Andrea Ferrari, Director of the Cambridge Graphene Centre.""This is a significant step forward to enable fully wearable and flexible devices.
This cements the Cambridge graphene technology cluster and shows how an effective academic-industrial partnership is key to help move graphene from the lab to the factory floor.""
""The potential of graphene is well-known, but industrial process engineering is required now to transition graphene from laboratories to industry,
"said Indro Mukerjee, CEO of Plastic Logic.""This demonstration puts Plastic Logic at the forefront of this development,
which will soon enable a new generation of ultra-flexible and even foldable electronics"This joint effort between Plastic Logic
within the'realising the graphene revolution'initiative. This will target the realisation of an advanced, full colour, OELD based display within the next 12 months h
#Team develops ultra sensitive biosensor from molybdenite semiconductor Move over graphene. An atomically thin two-dimensional ultrasensitive semiconductor material for biosensing developed by researchers at UC Santa barbara promises to push the boundaries of biosensing technology in many fields from health care to environmental protection to forensic industries.
Based on molybdenum disulfide or molybdenite (Mos2) the biosensor materialsed commonly as a dry lubricanturpasses graphene's already high sensitivity offers better scalability
While graphene has attracted wide interest as a biosensor due to its two-dimensional nature that allows excellent electrostatic control of the transistor channel by the gate
and high surface-to-volume ratio the sensitivity of a graphene field-effect transistor (FET) biosensor is restricted fundamentally by the zero band gap of graphene that results in increased leakage current leading to reduced sensitivity
Graphene has been used among other things to design FETSEVICES that regulate the flow of electrons through a channel via a vertical electric field directed into the channel by a terminal called a gate.
Graphene has received wide interest in the biosensing field and has been used to line the channel and act as a sensing element
despite graphene's excellent characteristics its performance is limited by its zero band gap. Electrons travel freely across a graphene FETENCE it cannot be switched offhich in this case results in current leakages and higher potential for inaccuracies.
Much research in the graphene community has been devoted to compensating for this deficiency either by patterning graphene to make nanoribbons
or by introducing defects in the graphene layerr using bilayer graphene stacked in a certain pattern that allows band gap opening upon application of a vertical electric fieldor better control and detection of current.
Enter Mos2 a material already making waves in the semiconductor world for the similarities it shares with graphene including its atomically thin hexagonal structure and planar nature as well as
what it can do that graphene can't: act like a semiconductor. Monolayer or few-layer Mos2 have a key advantage over graphene for designing an FET biosensor:
They have a relatively large and uniform band gap (1. 2-1. 8 ev depending on the number of layers) that significantly reduces the leakage current
and increases the abruptness of the turn-on behavior of the FETS thereby increasing the sensitivity of the biosensor said Banerjee.
Additionally according to Deblina Sarkar a Phd student in Banerjee's lab and the lead author of the article two-dimensional Mos2 is relatively simple to manufacture.
Professor Banerjee and his team have identified a breakthrough application of these nanomaterials and provided new impetus for the development of low-power
New rapid synthesis developed for bilayer graphene and high-performance transistors More information: ACS Nano pubs. acs. org/doi/abs/10.1021/nn500914 i
Ever since the discovery of graphene a single layer of carbon that can be extracted from graphite with adhesive tape scientists have been rapidly exploring the world of two-dimensional materials These materials have unique properties not seen in their bulk form.
Like graphene Mos2 is made up of layers that are bonded weakly to each other so they can be separated easily.
Graphene is inefficient at light emission because it has no band gap. Combining electronics and photonics on the same integrated circuits could drastically improve the performance and efficiency of mobile technology.
#Ultrafast graphene based photodetectors with data rates up to 50 GBIT/s In cooperation with Alcatel Lucent Bell labs researcher from AMO realized the worldwide fastest Graphene based photodetectors.
Graphene a two-dimensional layer of carbon atoms is currently one of the most promising materials for future ultrafast and compact telecommunication systems.
In the current work Graphene based photodetectors were integrated in a conventional silicon photonic platform designed for future on-chip applications in the area of ultrafast data communication.
In addition the specific features of Graphene-based photodetectors like dark current free and high speed operation
not only set a new benchmark for graphene based photodetectors but also demonstrate for the first time that Graphene based photodetectors surpass comparable detectors based on conventional materials concerning maximal data rates.
The work was supported by the European commission through the Flagship project Graphene and the integrated project Grafol as well as the DPG supported project Gratis.
The publication is published in the international renowned journal ACS Photonics and was chosen as Editor's Choice article.
Graphene and related materials promise cheap flexible printed cameras More information: 50 GBIT/s photodetectors based on wafer-scale graphene for integrated silicon photonic communication systems.
ACS Photonics Just Accepted Manuscript. DOI: 10.1021/ph500160 6
#Graphene reinvents the future For many scientists the discovery of one-atom-thick sheets of graphene is hugely significant something with the potential to affect just about every aspect of human activity and endeavour.
Graphene is hidden inside graphite an ore that has not been particularly sought after in the past. But a few years ago it revealed a secret.
At the molecular level it is a unique two-dimensional molecule: an electrically conductive latticelike layer just one carbon atom thick.
Graphene has usually cautious physicists and chemists itching with excitement mesmerised by the possibilities starting to take shape from flexible electronics embedded into clothing to biomedicine (imagine synthetic nerve cells) vastly superior forms of energy storage (tiny
But despite the extraordinary potential for graphene's properties the stumbling block has been to get it into a useable form.
Professor Li has invented a cost-effective and scalable way to split graphite into microscopic graphene sheets and dissolve them in water.
From this he has developed two new graphene technology platforms the starting points for developing commercial applications. One is a graphene gel that works as a supercapacitor electrode
and the second is a 3-D porous graphene foam. The graphene gel provides the same functionality as porous carbon a material currently sourced from coconut husks for use in supercapacitors and other energy conversion and storage technologies but with vastly enhanced performance.
Supercapacitors have an expanding range of applications as their capabilities increase from powering computer memory backup to powering electric vehicles.
Professor Li's team has also been able to give graphene a more functional 3-D form by engineering it into an elastic graphene foam that retains its extraordinary qualities.
Professor Li likened his developments to having invented bricks and said it was time to bring in architects
#Competition for graphene: Researchers demonstrate ultrafast charge transfer in new family of 2-D semiconductors A new argument has just been added to the growing case for graphene being bumped off its pedestal as the next big thing in the high-tech world by the two-dimensional semiconductors
known as MX2 materials. An international collaboration of researchers led by a scientist with the U s. Department of energy (DOE)' s Lawrence Berkeley National Laboratory (Berkeley Lab) has reported the first experimental observation of ultrafast charge transfer in photo-excited
These 2d semiconductors feature the same hexagonal"honeycombed"structure as graphene and superfast electrical conductance,
but, unlike graphene, they have natural energy band-gaps. This facilitates their application in transistors and other electronic devices because
unlike graphene, their electrical conductance can be switched off.""Combining different MX2 layers together allows one to control their physical properties,
#Scientists fabricate defect-free graphene set record reversible capacity for Co3o4 anode in Li-ion batteries Graphene has already been demonstrated to be useful in Li-ion batteries,
despite the fact that the graphene used often contains defects. Large-scale fabrication of graphene that is chemically pure, structurally uniform,
and size-tunable for battery applications has remained so far elusive. Now in a new study, scientists have developed a method to fabricate defect-free graphene (df-G) without any trace of structural damage.
Wrapping a large sheet of negatively charged df-G around a positively charged Co3o4 creates a very promising anode for high-performance Li-ion batteries.
current methods to fabricate high-quality graphene fall into two categories: mechanical approaches and chemical approaches. While mechanical cleavage provides high-quality graphene,
its low yield makes it insufficient for large-scale production. Chemical approaches, on the other hand, can produce bulk quantities
which causes the layers to expand away from each other to form graphene nanosheets that could later be cooled
because when a single graphene sheet is wrapped around a bundle of Co3o4 particles, the Co3o4 particles are prevented from becoming pulverized
whereas anodes with an imperfect graphene layer rapidly decrease with cycling. The large size of the graphene plays a key role in the performance
because a larger size provides a higher cycling stability of the nanosized anode materials by improving their mechanical integrity.
#Graphene rubber bands could stretch limits of current healthcare New research published today in the journal ACS Nano identifies a new type of sensor that can monitor body movements
Now researchers from the University of Surrey and Trinity college Dublin have treated for the first time common elastic bands with graphene to create a flexible sensor that is sensitive enough for medical use
By fusing this material with graphene -which imparts an electromechanical response on movement the team discovered that the material can be used as a sensor to measure a patient's breathing heart rate
but our graphene-infused rubber bands could really help to revolutionise remote healthcare said Dr Alan Dalton from the University of Surrey.
#New graphene framework bridges gap between traditional capacitors batteries Researchers at the California Nanosystems Institute (CNSI) at UCLA have set the stage for a watershed in mobile energy storage by using a special graphene material
The material, called a holey graphene framework, has perforated a three-dimensional structure characterized by tiny holes;
In their study, published online August 8 in the journal Nature Communications, the CNSI researchers led by Duan used a highly interconnected 3d holey graphene framework as the electrode material to create an EC with unprecedented performance.
Graphene research on the cusp of new energy capabilities (Phys. org) There remains a lot to learn on the frontiers of solar power research particularly
Under the guidance of Canada Research Chair in Materials science with Synchrotron radiation Dr. Alexander Moewes University of Saskatchewan researcher Adrian Hunt spent his Phd investigating graphene oxide a cutting-edge material that he hopes will shape the future
To understand graphene oxide it is best to start with pure graphene which is a single-layer sheet of carbon atoms in a honeycomb lattice that was made first in 2004 by Andre Geim
All of this makes graphene a great candidate for solar cells. In particular its transparency and conductivity mean that it solves two problems of solar cells:
whereas graphene could be very cheap. Carbon is said abundant Hunt. Although graphene is a great conductor it is not very good at collecting the electrical current produced inside the solar cell
which is why researchers like Hunt are investigating ways to modify graphene to make it more useful.
Graphene oxide the focus of Hunt's Phd work has forced oxygen into the carbon lattice which makes it much less conductive but more transparent and a better charge collector.
Whether or not it will solve the solar panel problem is yet to be seen and researchers in the field are building up their understanding of how the new material works.
and SGM beamlines at the Canadian Light source as well as a Beamline 8. 0. 1 at the Advanced Light source Hunt set out to learn more about how oxide groups attached to the graphene lattice changed it
and how in particular they interacted with charge-carrying graphene atoms. Graphene oxide is fairly chaotic. You don't get a nice simple structure that you can model really easily but
I wanted to model graphene oxide and understand the interplay of these parts. Previous models had seemed simplistic to Hunt
and he wanted a model that would reflect graphene oxide's true complexity. Each different part of the graphene oxide has a unique electronic signature.
Using the synchrotron Hunt could measure where electrons were on the graphene and how the different oxide groups modified that.
He showed that previous models were incorrect which he hopes will help improve understanding of the effects of small shifts in oxidization.
Moreover he studied how graphene oxide decays. Some of the oxide groups are not stable and can group together to tear the lattice;
others can react to make water. If graphene oxide device has water in it and it is heated up the water can actually burn the graphene oxide and produce carbon dioxide.
It's a pitfall that could be important to understand in the development of long-lasting solar cells where sun could provide risky heat into the equation.
More research like this will be the key to harnessing graphene for solar power as Hunt explains.
There's this complicated chain of interreactions that can happen over time and each one of those steps needs to be addressed
Super-stretchable yarn is made of graphene More information: Hunt Adrian Ernst Z. Kurmaev and Alex Moewes.
A Re evaluation of How Functional Groups Modify the Electronic Structure of Graphene oxide. Advanced Materials (2014.
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