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Graphene synthesis and applications:
ABSTRACT: Graphene, a two-dimensional, single-layer sheet of sp2 hybridized carbon atoms, has attracted tremendous attention, owing to its exceptional physical and chemical properties such as thermal stability, and mechanical strength, transparency, selective permeability, light weight, flexible, thin, biodegradable. Other forms of Graphene-related materials, like Graphene oxide, reduced Graphene oxide, and exfoliated graphite, have been produced on large scale. The promising properties together with the ease of processibility and functionalization make graphene based materials ideal candidates for incorporation with various functional materials. Importantly, graphene and its derivatives have been used in a wide range of applications, such as electronic, solar and photonic devices, clean energy, sensors, 3D-printing, super capacitors. Its future applications include water filtration, prosthetic organs, and flexible screens. In this paper, after a general introduction to Graphene and its derivatives, the characteristics, properties, and applications of Graphene based materials are discussed. Graphene synthesis being an important affair is also studied in this paper, methods like CVD, ion implation, arc discharge and many more are discussed. In this paper I have worked upon, different properties of graphene to make better and reliable electronics, improving future technology for completing the ultimate goal of increasing standards of human race.
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The 'wonder material' known as graphene can revolutionize technology of the world.
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The 'wonder material' known as graphene can revolutionize technology of the world.
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As each era is defined by the material's age like STONE AGRE,BRONZE AGE etc,soon this very era is going to be regarded as GRAPHENE era because of its extraordinary properties.If it comes to the world in an easy production manner,each and every thing on this earth will have the best priority of its costruction as GRAPHENE. You will surely wanna be a GRAPHENE after reading the full article. [full work on by ISHAAN SANEHI]
PRESENTATION OUTLINE
Introduction,History of Nanotechnology,What is Nanotechnology, Definition of Nano,History of Graphene,Graphene,Why Nanotechnology,Size of Nanotechnology,What is Graphene, Properties of Graphene,Graphene Structure,Types of Graphene ,Synthesize Graphene,Applications,Conclusions,References
A short description about Graphene. Gives information about the discovery, properties, applications. This short file contains all the major information about graphene and appropriate references for further research.
Graphene: its increasing economic feasibility Jeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how Graphene is becoming economic feasible for an increasing number of applications as its price falls and its quality/performance rises through improvements in chemical vapor deposition processes. Graphene is one of the strongest materials discovered, has high electronic and thermal conductivities, and unusual optical properties. These slides describe a number of applications for which Graphene is gradually becoming economically feasible including displays, integrated circuits, solar cells, water desalination, and natural gas tanks.
Graphene_complete description_Introduction_history_synthesis_electrical appliactions other other miscellineus applcations,challeneges explained with full of animated diagrams.
If you need in PPT file with full of beautiful animations and transitions for FREE, then just email me on this adress:
kashifwattu798@gmail.com
ENJOY ...!!!
Properties and applications of graphene.
More introductions about graphene are in Alfa Chemistry.
https://www.alfa-chemistry.com/products/graphene-38.htm
Graphene, the amazing two-dimensional carbon nanomaterial, has attracted extensive interest in recent years and emerged as the most intensively studied material [1]. In 2004, Geim and Nosovelov at Manchester University successfully isolated single layer graphene by the mechanical cleavage of graphite crystal [2]. This ‘‘thinnest’’ known material exhibits extraordinary electronic, chemical, mechanical, thermal and optical properties which bestowed graphene as a miracle material of the 21st Century. From applicative perspectives, graphene holds a great promise with the potential to be used as energy-storage materials, in nanoelectronics, in catalysis, biomedical, in polymer composites and many more.
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Graphene Presentation
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
As each era is defined by the material's age like STONE AGRE,BRONZE AGE etc,soon this very era is going to be regarded as GRAPHENE era because of its extraordinary properties.If it comes to the world in an easy production manner,each and every thing on this earth will have the best priority of its costruction as GRAPHENE. You will surely wanna be a GRAPHENE after reading the full article. [full work on by ISHAAN SANEHI]
PRESENTATION OUTLINE
Introduction,History of Nanotechnology,What is Nanotechnology, Definition of Nano,History of Graphene,Graphene,Why Nanotechnology,Size of Nanotechnology,What is Graphene, Properties of Graphene,Graphene Structure,Types of Graphene ,Synthesize Graphene,Applications,Conclusions,References
A short description about Graphene. Gives information about the discovery, properties, applications. This short file contains all the major information about graphene and appropriate references for further research.
Graphene: its increasing economic feasibility Jeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how Graphene is becoming economic feasible for an increasing number of applications as its price falls and its quality/performance rises through improvements in chemical vapor deposition processes. Graphene is one of the strongest materials discovered, has high electronic and thermal conductivities, and unusual optical properties. These slides describe a number of applications for which Graphene is gradually becoming economically feasible including displays, integrated circuits, solar cells, water desalination, and natural gas tanks.
Graphene_complete description_Introduction_history_synthesis_electrical appliactions other other miscellineus applcations,challeneges explained with full of animated diagrams.
If you need in PPT file with full of beautiful animations and transitions for FREE, then just email me on this adress:
kashifwattu798@gmail.com
ENJOY ...!!!
Properties and applications of graphene.
More introductions about graphene are in Alfa Chemistry.
https://www.alfa-chemistry.com/products/graphene-38.htm
Graphene, the amazing two-dimensional carbon nanomaterial, has attracted extensive interest in recent years and emerged as the most intensively studied material [1]. In 2004, Geim and Nosovelov at Manchester University successfully isolated single layer graphene by the mechanical cleavage of graphite crystal [2]. This ‘‘thinnest’’ known material exhibits extraordinary electronic, chemical, mechanical, thermal and optical properties which bestowed graphene as a miracle material of the 21st Century. From applicative perspectives, graphene holds a great promise with the potential to be used as energy-storage materials, in nanoelectronics, in catalysis, biomedical, in polymer composites and many more.
For free download Subscribe to https://www.youtube.com/channel/UCTfiZ8qwZ_8_vTjxeCB037w and Follow https://www.instagram.com/fitrit_2405/ then please contact +91-9045839849 over WhatsApp.
Graphene Presentation
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A survey on supercapacitors and their applicationseSAT Journals
Abstract The need for more sustainable, capable energy storage has motivated a transformed scientific and commercial concern in advanced capacitor designs in which the suite of experimental techniques and ideas that comprise nanotechnology are playing a vital role. Capacitors might be charged and discharged speedily and are one of the primary building blocks of many types of electrical circuit, from microprocessors to large-scale power supplies, but generally have reasonably low energy storage potential when compared with batteries. The blende of nanorange materials with bespoke morphologies and properties to electrochemical supercapacitors is being intensively studied and observed .Recuperating and preserving energy of a moving vehicle as it slows down and accelerate the vehicle later by means of that preserved energy, can significantly increase fuel efficiencies of automobiles. Capacitors are one of the primary and basic building blocks of many types of electrical circuit. Therefore, an effort here is done to present a survey on supercapacitors. Key Words: Super capacitors, EDLC, Grapheme, nanocomposites
Graphene is one the wonder materials in modern world,I Shaunak Bhattacharya with help of my group mates has made this presentation. Since I referred to slideshare.net for my presentation it was my duty to give it something back. I would be really happy if my presentation comes handy to anyone.
GRAPHENE SYNTHESIS AND APPLICATION POSTERAman Gupta
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Graphene eplained by poster presentation
Solar power is looking more and more attractive, as other power generation
methods such as fossil fuels and nuclear power come under increasing scrutiny
Nano material solar cells shows special promise to both enhance efficiency of
solar energy conservation and also reduce the manufacturing cost
It increase efficiently by the absorption of light as well as the overall radiation
to electricity would help preserve the environment, decrease wastage, provide
electricity for rural areas, and have a wide array of commercial applications
due to its capabilities
Super Capacitor by NITIN GUPTA
NITIN GUPTA,CEO/FOUNDER/OWNER at "TECH POINT"
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Supercapacitors (Ultracapacitor) : Energy Problem Solver,Amit Soni
Capacitor, Basic design and terminology, Supercapacitor, History of Supercapacitor
Classification of Supercapacitors, Electrical Double layer capacitors,Pseudocapacitor
Hybrid Capacitor, Basic Design, Construction, Working , Technology used, Why these substances used ?, Features, Comparison, Applications , Advantages & Disadvantages
state of art materials, comparison with batteries, fuel cells, applications
Abstract
The Batteries form a significant part of many electronic devices. Typical electrochemical batteries or cells convert chemical energy into electrical energy. Batteries based on the charging ability are classified into primary and secondary cells. Secondary cells are widely used because of their rechargeable nature. Presently, battery takes up a huge amount of space and contributes to a large part of the device's weight. There is strong recent interest in ultrathin, flexible, safe energy storage devices to meet the various design and power needs of modern gadgets. New research suggests that carbon nanotubes may eventually provide the best hope of implementing the flexible batteries which can shrink our gadgets even more. The paper batteries could meet the energy demands of the next generation gadgets. A paper battery is flexible, ultra-thin energy storage and production device formed by combining carbon nanotubes with a conventional sheet of cellulose based paper. A paper battery acts as both a high-energy battery and super capacitor, combining two components that are separate in traditional electronics. This combination allows the battery to provide both long-term, steady power production and bursts of energy. Non- toxic, flexible paper batteries have the potential to power the next generation of electronics, medical devices and hybrid vehicles, allowing for radical new designs and medical technologies.
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Project Report- RFID Based Automated Toll Collection System using Arduino @ A...Aman Gupta
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ATCS usually known as “Automated Toll Collection System” is a new technology for collecting toll in a faster and more efficient way. It is a great alternative to long waiting at manual toll plazas. In order to overcome the wastage of time and fuel at same time we have come up with a concept of RFID based automated toll collection system using Arduino. RFID stands for Radio Frequency Identification; these cards are unique identities provided to every vehicle by Registration Office at each city. Whenever a vehicle with such Unique ID reaches the toll plaza, the RFID card reader attached on the toll plaza gate reads the card and transfers the unique ID to Arduino ATmega 328. Accordingly, the processor works and deducts a fixed money from the prepaid card. If the card’s ID is valid and has sufficient balance, the processor will command the DC motor to start and open the gate, letting the vehicle to pass. On passing from the gate the screen will show the deducted and current balance of the card. If the card is not valid or low in balance, it will prompt to move the vehicle to manual toll collection lane. Furthermore, a message will be sent to the owner’s registered mobile number with the same details along with the location of the toll booth.
Summer Internship Report For PLC Programming of Traffic light through Ladder ...Aman Gupta
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An industrial PLCs system is used for the development of the controls of machinery. This paper describes the PLCs systems in terms of their architecture, their interface to the process hardware, the functionality and the application development facilities they provide. Some attention is also paid to the industrial standards to which they abide their planned evolution as well as the potential benefits of their use. Ladder Logic is a graphical programming language, initially programmed with simple contacts that simulates the opening and closing of relays. Ladder Logic programming has been expanded to include functions such as Counters, Timers, shift Registers and math operations. Ladder logic is a method of drawing electrical logic schematics. It is now a graphical language very popular for programming Programmable Logic Controllers (PLCs). It was originally invented to describe logic made from relays. The name is based on the observation that programs in this language resemble ladders, with two vertical "rails" and a series of horizontal "rungs" between them.
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Programmable Logic Controller (PLC) is a specialized computing system used for control of industrial machines and processes.
mobile ad-hoc network (MANET) and its applicationsAman Gupta
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A mobile ad hoc network (MANET) is a continuously self-configuring, infrastructure-less network of mobile devices connected without wires. Ad hoc is Latin and means "for this purpose
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GRAPHENE SYNTHESIS AND ITS APPLICATIONS TERM PAPER PRESENTATIONAman Gupta
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Graphene synthesis process and its current and future applications explained in brief
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Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
GRAPHENE: THE MIRACLE MATERIAL, SYNTHESIS AND APPLICATION RESEARCH PAPER PRESENTATION
1. 1
Graphene: Future Ahead
Aman Gupta1
, Vimal Kishor Yadav2
, Sudeep Giri3
Electronics and Communication, Amity School of Engineering and Technology,
Amity University, Madhya Pradesh, India
1guptaaman15031994@gmail.com
2vimal.iitb@gmail.com
Abstract- Graphene, a two-dimensional, single-layer sheet of sp2
hybridized carbon atoms, has attracted tremendous attention, owing
to its exceptional physical and chemical properties such as thermal stability, and mechanical strength, transparency, selective
permeability, light weight, flexible, thin, biodegradable. Other forms of Graphene-related materials, like Graphene oxide, reduced
Graphene oxide, and exfoliated graphite, have been produced on large scale. The promising properties together with the ease of
processibility and functionalization make graphene based materials ideal candidates for incorporation with various functional
materials. Importantly, graphene and its derivatives have been used in a wide range of applications, such as electronic, solar and
photonic devices, clean energy, sensors, 3D-printing, super capacitors. Its future applications include water filtration, prosthetic organs,
and flexible screens. In this paper, after a general introduction to Graphene and its derivatives, the characteristics, properties, and
applications of Graphene based materials are discussed. Graphene synthesis being an important affair is also studied in this paper,
methods like CVD, ion implation, arc discharge and many more are discussed. In this paper I have worked upon, different properties of
graphene to make better and reliable electronics, improving future technology for completing the ultimate goal of increasing standards
of human race.
Keywords- sp2 Hybridization, Chemical Vapour Deposition, Super Capacitors, Terahertz Electronics, Printed Technology.
I. INTRODUCTION
In simple terms, graphene is a thin layer of pure carbon; it is
a single, tightly packed layer of carbon atoms that are bonded
together in a hexagonal honeycomb lattice. In more complex
terms, it is an allotrope of carbon in the structure of a plane of
sp2 bonded atoms with a molecule bond length of 0.142
nanometres. Layers of graphene stacked on top of each other
form graphite, with an interplanar spacing of 0.335 nm.
It is the thinnest compound known to man at one atom thick,
lightest material (with 1 sq meters coming in at around 0.77
mg), the strongest compound (between 100-300 times
stronger than steel and with a tensile stiffness of 150,000,000
psi), the best conductor of heat at room temperature (at
(4.84±0.44) × 103 to (5.30±0.48) × 103 W·m−1·K−1) and
also best conductor of electricity known (studies have shown
electron mobility at values of more than 15,000
cm2·V−1·s−1). Other notable properties of graphene are its
unique levels of light absorption at πα ≈ 2.3% of white light,
and its potential suitability for use in spin transport. André
Geim and Konstantin Novoselov at the University of
Manchester won the Nobel Prize in Physics in 2010 for
ground breaking experiments regarding the two-
dimensional material graphene.
II. ENERGY STORAGE
One area of research that is being very highly studied is
energy storage. While all areas of electronics have been
advancing over a very fast rate over the last few decades (in
reference to Moore’s law which states that the number of
transistors used in electronic circuitry will double every 2
years), the problem has always been storing the energy in
batteries and capacitors when it is not being used. These
energy storage solutions have been developing at a much
slower rate. The problem is this: a battery can potentially
hold a lot of energy, but it can take a long time to charge, a
capacitor, on the other hand, can be charged very quickly, but
can’t hold that much energy (comparatively speaking). The
solution is to develop energy storage components such as
either a supercapacitors or a battery that is able to provide
both of these positive characteristics without compromise.
2. 2
Currently, scientists are working on enhancing the
capabilities of lithium ion batteries (by incorporating
graphene as an anode) to offer much higher storage capacities
with much better longevity and charge rate. Also, graphene is
being studied and developed to be used in the manufacture of
supercapacitors which are able to be charged very quickly,
yet also be able to store a large amount of electricity.
Graphene based micro-supercapacitors will likely be
developed for use in low energy applications such as smart
phones and portable computing devices and could potentially
be commercially available within the next 5-10 years.
Graphene-enhanced lithium ion batteries could be used in
much higher energy usage applications such as electrically
powered vehicles, or they can be used as lithium ion batteries
are now, in smart phones, laptops and tablet PCs but at
significantly lower levels of size and weight.
Scientists have been struggling to develop energy storage
solutions such as batteries and capacitors that can keep up
with the current rate of electronic component evolution for a
number of years.
Unfortunately, the situation we are in now is that while we
are able to store a large amount of energy in certain types of
batteries, those batteries are very large, very heavy, and
charge and release their energy relatively slowly.
Capacitors, on the other hand, are able to be charged and
release energy very quickly, but can hold much less energy
than a battery. Graphene application developments have led
to new possibilities for energy storage, with high charge and
discharge rates, which can be made cheaply.
But before we go into specific details, it would be sensible to
first outline basics of energy storage and the potential goals
of developing graphene as supercapacitors.
III. CAPACITORS AND SUPERCAPACITORS EXPLAINED
A capacitor is an energy storage medium similar to an
electrochemical battery. Most batteries, while able to store a
large amount of energy are relatively inefficient in
comparison to other energy solutions such as fossil fuels.
It is often said that a 1kg electrochemical battery is able to
produce much less energy than 1 litre of gasoline; but this
kind of comparison is extremely vague, and should be
ignored. In fact, some electrochemical batteries can be
relatively efficient, but that doesn’t get around the primary
limiting factor in batteries replacing fossil fuels.
High capacity batteries take a long time to charge. This is
why electrically powered vehicles have not taken-off as well
as we expected twenty or thirty years ago.
While you are now able to travel 250 miles or more on one
single charge in a car such as the Tesla Model S, it could take
you over 43 hours to charge the vehicle using a standard 120v
wall socket in order to drive back home. This is not
acceptable for many car users. Capacitors, on the other hand,
are able to be charged at a much higher rate, but store
somewhat less energy.
Figure 1 Formation of a Graphene capacitor
Supercapacitors, also known as ultra-capacitors, are able to
hold hundreds of times the amount of electrical charge as
standard capacitors, and are therefore suitable as a
replacement for electrochemical batteries in many industrial
and commercial applications. Supercapacitors also work in
very low temperatures; a situation that can prevent many
types of electrochemical batteries from working.
For these reasons, supercapacitors are already being used in
emergency radios and flashlights, where energy can be
produced kinetically (by winding a handle, for example) and
then stored in supercapacitors for the device to use.
A conventional capacitor is made up of two layers of
conductive materials (eventually becoming positively and
negatively charged) separated by an insulator. What dictates
the amount of charge a capacitor can hold is the surface area
of the conductors, the distance between the two conductors
and also the dielectric constant of the insulator.
Supercapacitors are slightly different in the fact that they do
not contain a solid insulator.
While supercapacitors are able to store much more energy
than standard capacitors, they are limited in their ability to
withstand high voltage. Electrolytic capacitors are able to run
at hundreds of volts, but supercapacitors are generally limited
to around 5 volts. However, it is possible to engineer a chain
of supercapacitors to run at high voltages as long as the series
is properly designed and controlled.
3. 3
IV. GRAPHENE-BASED SUPERCAPACITORS
Supercapacitors, unfortunately, are currently very expensive
to produce, and at present the scalability of supercapacitors in
industry is limiting the application options as energy
efficiency is offset against cost efficiency. This idea of
creating graphene monolayers by using thermo lithography is
not necessarily a new one, as scientists from the US were
able to produce graphene nanowires by using thermochemical
nanolithography back in 2010; however, new method avoids
use of atomic force microscope in favour of commercially
available laser device that is already prevalent in many homes
around the world.
Well, graphene is essentially a form of carbon, and while
activated carbon has an extremely high relative surface area,
graphene has substantially more. As we have already
highlighted, one of the limitations to the capacitance of ultra-
capacitors is the surface area of the conductors. If one
conductive material in a supercapacitor has a higher relative
surface area than another, it will be better at storing
electrostatic charge.
The efficiency of the supercapacitor is the important factor to
bear in mind. In the past, scientists have been able to create
supercapacitors that are able to store 150 Farads per gram,
but some have suggested that the theoretical upper limit for
graphene-based supercapacitors is 550 F/g. This is
particularly impressive when compared against current
technology: a commercially available capacitor able to store
1 Farad of electrostatic energy at 100 volts would be about
220mm high and weigh about 2kgs, though current
supercapacitor technology is about the same, in terms of
dimensions relative to energy storage values, as a graphene-
based supercapacitor would be.
V. THE FUTURE FOR GRAPHENE-BASED
SUPERCAPACITORS
Due to the lightweight dimensions of graphene based
supercapacitors and the minimal cost of production coupled
with graphene’s elastic properties and inherit mechanical
strength, we will almost certainly see technology within the
next five to ten years incorporating these supercapacitors.
Also, with increased development in terms of energy storage
limits for supercapacitors in general, graphene-based or
hybrid supercapacitors will eventually be utilized in a number
of different applications.
Vehicles that utilize supercapacitors are already prevalent in
our society. One Chinese company is currently
manufacturing buses that incorporate supercapacitor energy
recovery systems, such as those used on Formula 1 cars, to
store energy when braking and then converting that energy to
power the vehicle until the next stop.
Additionally, we will at some point in the next few years
begin to see mobile telephones and other mobile electronic
devices being powered by supercapacitors as not only can
they be charged at a much higher rate than current lithium-
ion batteries, but they also have the potential to last for a
vastly greater length of time.
Other current and potential uses for supercapacitors are as
power backup supplies for industry or even our own homes.
Businesses can invest in power backup solutions that are able
to store high levels of energy at high voltages, effectively
offering full power available to them, to reduce the risk of
having to limit production due to inadequate amounts of
power.
Figure 2 Super capacitors made of Graphene
Alternatively, if you have a fuel cell vehicle that is able to
store a large amount of electrical energy, then why not use it
to help power your home in the event of a power outage?
We can expect that this scenario of using advanced energy
storage and recovery solutions will become much more
widely used in the coming years as the efficiency and energy
density of supercapacitors increases, and the manufacturing
costs decrease.
While graphene-based supercapacitors are currently a viable
solution in the future, technology needs to be developed to
make this into a reality. But rest assured, many companies
around the world are already trialling products using this
technology and creating new ways to help subsidise the use
of fossil-fuels and toxic chemicals in our ever-demanding
strive for energy.
Being able to create super capacitors out of graphene will
possibly is the largest step in electronic engineering in a very
long time. While the development of electronic components
has been progressing at a very high rate over the last 20
years, power storage solutions such as batteries and
capacitors have been the primary limiting factor due to size,
power capacity and efficiency.
4. 4
In initial tests carried out, laser-scribed graphene (LSG)
supercapacitors (with graphene being the most electronically
conductive material known, at 1738 Siemens per meter
(compared to 100 SI/m for activated carbon)), were shown to
offer power density comparable to that of high-power
lithium-ion batteries that are in use today. Not only that, but
also LSG supercapacitors are highly flexible, light, quick to
charge, thin and as previously mentioned, comparably very
inexpensive to produce.
Graphene is also being used to boost not only the capacity
and charge rate of batteries but also the longevity. Currently,
while such materials as silicone are able to store large
amounts of energy, that potential amount diminishes
drastically on every charge or recharge. With graphene tin
oxide being used as an anode in lithium ion batteries for
example, batteries can be made to last much longer between
charges (potential capacity has increased by a factor of 10),
and with almost no reduction in storage capacity between
charges, effectively making technology such as electronically
powered vehicles a much more viable transport solution in
the future.
This means that batteries can be developed to last much
longer and at higher capacities than previously realised. Also,
it means that electronic devices may be able to be charged
within seconds, rather than minute or hours and have hugely
improved longevity.
VI. ELECTRONIC PROPERTIES
One of the most useful properties of graphene is that it is a
zero-overlap semimetal with very high electrical
conductivity. Carbon atoms have a total of 6 electrons; 2 in
the inner shell and 4 in outer shell. The 4 outer shell electrons
in an individual carbon atom are available for chemical
bonding, but in graphene, each atom is connected to 3 other
carbon atoms, leaving 1 electron freely available for
electronic conduction. These highly-mobile electrons are
called pi (π) elec.
Figure 3 Reason for Graphene's electronic properties
The electronic properties of graphene are dictated by the
bonding and anti-bonding of these pi orbitals.Combined
research over the last 50 years has proved that at the Dirac
point in graphene, electrons and holes have zero effective
mass. This occurs because the energy – movement relation is
linear for low energies near the 6 individual corners of the
Brillouin zone. Due to the zero density of states at the Dirac
points, electronic conductivity is actually quite low.
Tests have shown that the electronic mobility of graphene is
very high, with previously reported results above 15,000
cm2·V−1·s−1. It is said that graphene electrons act very
much like photons in their mobility due to their lack of mass.
These charge carriers are able to travel sub-micrometre
distances without scattering; a phenomenon known as
ballistic transport. Silicon dioxide as the substrate, for
example, mobility is potentially limited to 40,000
cm2·V−1·s−1.
VII. GRAPHENE FOR TERAHERTZ ELECTRONICS
Conventional electronic devices are made up of silicon
semiconductors, metal contacts, doped junctions or barrier
structures, etc. Each of these components must be added
vertically on top of one another. In contrast, we have recently
developed novel concepts of nano-diodes and transistors that
are based on single-layered device architecture.
By using nano-scale electronic channels and tailoring the
geometrical symmetry, the new devices have been
demonstrated to have extremely high speed up to 1.5THz
(1,500GHz), making them by far the fastest Nano devices to
date The immediate applications include high-speed
electronics for next generation of computations and
communications, far-infrared THz detection and emission,
ultra-high sensitive chemical sensors, etc.
VIII. PHOTOVOLTAIC CELLS
Offering very low levels of light absorption (at around 2.7%
of white light) whilst also offering high electron mobility
means that graphene can be used as an alternative to silicon
or ITO in the manufacture of photovoltaic cells. Silicon is
currently widely used in the production of photovoltaic cells,
but while silicon cells are very expensive to produce,
graphene based cells are potentially much less so. When
materials such as silicon turn light into electricity it produces
a photon for every electron produced, meaning that a lot of
potential energy is lost as heat.
Recently published research has proved that when graphene
absorbs a photon, it actually generates multiple electrons.
Also, while silicon is able to generate electricity from certain
wavelength bands of light, graphene is able to work on all
wavelengths, meaning that graphene has the potential to be as
efficient as, silicon, ITO or gallium arsenide.
5. 5
Being flexible and thin means that graphene based
photovoltaic cells could be used in clothing; to help recharge
your mobile phone, or even used as retro-fitted photovoltaic
window screens or curtains to help power your home.
IX. GRAPHENE SENSORS
University of Manchester scientists were the first to
demonstrate single-atom sensitivity in graphene Hall-bar
devices. The most sensitive electronic detection is achieved
by constructing a Hall-bar with graphene. This transverse
Hall resistivity is very sensitive to changes in carrier
concentration.
The binding event between the graphene sensor and analyte
leads to the donation or withdrawal of an electron from the
graphene, which changes its electrical conductivity which can
be measured. When a device is fabricated with a graphene
sheet suspended in free space between two electrodes, it has a
resonance frequency of vibration proportional to its mass.
X. GRAPHENE- PRINTED TECHNOLOGY
Superior properties of nanomaterials were utilized in new
type of polymer composition for emerging technology-
printed electronics. This is new trend in production of
electronic devices, providing ability to manufacture low-cost
and disposable electronic circuits using printed tech. called
screen printing, roll to roll and ink-jet.
Figure 4 Graphene conductive ink used in print-technology
The use of nanostructures and polymer compositions filled
them are topic of interest in fabrication of new type printed
electronics circuits, dedicated to transparent electrodes,
elastic displays and photovoltaics, various types of sensors(
pressure, temp., biochemical) and in tectonics. We can build
printed circuits using graphene nanoplates. We can produce
resistive and conductive layers containing graphene with use
of screen printing and spray coating techniques.
XI. CREATING GRAPHENE VIA CHEMICAL VAPOUR
DEPOSITION
There are different ways in which graphene monolayers can
be created or isolated, but by far the most popular way at this
moment in time is by using a process called chemical vapour
deposition. Chemical vapour deposition, or CVD, is a method
which can produce relatively high quality graphene,
potentially on a large scale. The CVD process is reasonably
straightforward, although some specialist equipment is
necessary, and in order to create good quality graphene it is
important to strictly adhere to guidelines set concerning gas
volumes, pressure, temperature, and time duration.
XII. CVD PROCESS
Simply put, CVD is a way of depositing gaseous reactants
onto a substrate. The way CVD works is by combining gas
molecules in a reaction chamber which is typically set at
ambient temperature. When the combined gases come into
contact with the substrate within the reaction chamber a
reaction occurs that create a material film on the substrate
surface. The waste gases are then pumped from the reaction
chamber. The temperature of the substrate is a primary
condition that defines the type of reaction that will occur.
During the CVD process, the substrate is usually coated a
very small amount, at a very slow speed, often described in
microns of thickness per hour. The solid compound or
compounds is/are vaporized, and then deposited onto a
substrate via condensation.
The benefits of using CVD to deposit materials onto a
substrate are that the quality of the resulting materials is
usually very high. Other common characteristics of CVD
coatings include imperviousness, high purity, fine grained
and increased hardness over other coating methods. It is a
common solution for the deposit of films in the
semiconductor industry, as well as in optoelectronics, due to
the low costs involved.
Although there are number of different formats of CVD, most
modern processes come under two headings separated by the
chemical vapour deposition operating pressure: LPCVD, and
UHVCVD. LPCVD (low pressure CVD), UHVCVD (ultra-
high vacuum CVD).
The disadvantages to using CVD to create material coatings
are that the gaseous by-products of the process are usually
very toxic. This is because the precursor gases used must be
highly volatile in order to react with the substrate, but not so
volatile that it is difficult to deliver them to the reaction
chamber. During the CVD process, the toxic by-products are
removed from the reaction chamber by gas flow to be
disposed of properly.
6. 6
XIII. FUNDAMENTAL PROCESSES IN THE CREATION OF
CVD GRAPHENE
CVD graphene is created in two steps, the precursor pyrolysis
of a material to form carbon, and the formation of the carbon
structure of graphene using the disassociated carbon atoms.
The first stage, the pyrolysis to disassociated carbon atoms,
must be carried out on the surface of the substrate to prevent
the precipitation of carbon clusters during the gas phase.
The problem with this is that the pyrolytic decomposition of
precursors requires extreme levels of heat, and therefore
metal catalysts must be used to reduce the reaction
temperature.
The second phase of creating the carbon structure out of the
disassociated carbon atoms also requires a very high level of
heat (over 2500 degrees Celsius).
The problem with using catalysts is that you are effectively
introducing more compounds into the reaction chamber,
which will have an effect on the reactions inside the chamber.
One example of these effects is the way the carbon atoms
dissolve into certain substrates such as Nickel during the
cooling phase.
What all this means is that it is vitally important that the
CVD process is very stringently co-ordinated, and that
controls are put in place at every stage of the process to
ensure that the reactions occur effectively, and that quality of
graphene produced is of the highest attainable.
XIV. PROBLEMS ASSOCIATED WITH CVD GRAPHENE
In order to create monolayer or few graphene on a substrate,
scientists must first overcome biggest issue with the methods
that have been observed so far. The first major problem is
that while it is possible to create high quality graphene on a
substrate using CVD, successful separation or exfoliation of
graphene from substrate has been a bit of a stumbling block.
The reason for this is primarily because the relationship
between graphene and the substrate it is ‘grown’ on is not yet
fully understood, so it is not easy to achieve separation
without damaging the structure of the graphene or affecting
the properties of the material. The techniques on how to
achieve this separation differ depending on the type of
substrate used. Often scientists can choose to dissolve the
substrate in harmful acids, but this process commonly affects
the quality of graphene produced.
One alternative method that has been researched involves the
creation of CVD graphene on a copper (Cu) substrate (in this
example, Cu is used as a catalyst in the reaction).
During CVD a reaction occurs between the copper substrate
and the graphene that create a high level of hydrostatic
compression, coupling the graphene to the substrate. It has
been shown to be possible; however, to intercalate a layer of
copper oxide between the graphene and the copper substrate
to reduce this pressure and enable the graphene to be
removed relatively easily.
Figure 5 CVD process to make Graphene
Scientists have also been looking into using (Poly methyl
methacrylate) as a support polymer to facilitate the transfer of
graphene onto an alternate substrate. With this method,
graphene is coated with PMMA, and the previous substrate is
etched. However, PMMA has been shown to be the most
effective at transferring the graphene without excessive
damage.
XV. CURRENT AND POTENTIAL SOLUTIONS
In terms of overcoming these issues, scientists have been
developing more complex techniques and guidelines to
follow in order to create the highest quality of graphene
possible. One introductory technique to reducing the effects
of these issues is by treating the substrate before the reaction
takes place. A copper substrate can be chemically treated to
enable reduced catalytic activity, increase the Cu grain size
and rearrange the surface morphology in order to facilitate
the growth of graphene flakes that contain fewer
imperfections.
This point of treating the substrate prior to deposition is
something that will continue to be researched for a long time,
as we slowly learn how to modify the structure of graphene to
suit different applications. For example, in order to enable
graphene to be effectively used in superconductors, doping
must be carried out on the material in order to create a band-
gap. This process could potentially be something that is
carried out on a substrate before deposition occurs rather than
treating the material after CVD.
7. 7
XVI. GRAPHENE: OTHER APPLICATIONS AND USES
Biological Engineering
Bioengineering will certainly be a field in which graphene
will become a vital part of in future. With graphene offering a
large surface area, high electrical conductivity, thinness and
strength, it would make a good candidate for the development
of fast and efficient bioelectric sensory devices, with the
ability to monitor such things as glucose levels, haemoglobin
levels, cholesterol and even DNA sequencing. It is able to be
used as an antibiotic or even anticancer treatment.
Optical Electronics
One particular area in which we will soon begin to see
graphene used on a commercial scale is that in
optoelectronics; specifically touch screens, liquid crystal
displays (LCD) and organic light emitting diodes (OLEDs).
For a material to be able to be used in optoelectronic
applications, it must be able to transmit more than 90% of
light and also offer electrical conductive properties exceeding
1 x 106 Ω1m1 and therefore low electrical
resistance. Graphene is almost completely transparent
material and is able to optically transmit up to 97.7% of light.
Ultrafiltration
Another standout property of graphene is that while it allows
water to pass through it, it is almost completely impervious to
liquids and gases (even relatively small helium molecules).
This means that graphene could be used as an ultrafiltration
medium to act as a barrier between two substances. The
benefit of using graphene is that it is only 1 single atom thick
and can also be developed as a barrier that electronically
measures strain and pressures between the 2 substances
(amongst many other variables).
Figure 6 Removing CO2 from water on passing through
graphene
A team of researchers at Columbia University have managed
to create monolayer graphene filters with pore sizes as small
as 5nm (currently, advanced nonporous membranes have
pore sizes of 30-40nm).
While these pore sizes are extremely small, as graphene is so
thin, pressure during ultrafiltration is reduced. Co-currently,
graphene is much stronger and less brittle than aluminium
oxide. Well, it could mean that graphene is developed to be
used in water filtration systems, desalination systems and
efficient and economically more viable biofuel creation.
XVII. CONCLUSIONS
Graphene has rapidly changed its status from being an
unexpected and sometimes unwelcome newcomer to a rising
star and to a reigning champion. The professional scepticism
that initially dominated the attitude of many researchers
(including myself) with respect to graphene applications is
gradually evaporating under the pressure of recent
Developments. Still, it is the wealth of new physics –
observed, expected and hoped for – which is driving the area
form the moment.
Research on graphene’s electronic properties is now matured
but is unlikely to start fading any time soon, especially
because of the virtually unexplored opportunity to control
quantum transport by strain engineering and various
structural modifications. Even after that, graphene will
continue to stand out as a truly unique item in them arsenal of
condensed matter physics. Research on graphene’s non-
electronic properties is just gearing up, and this should bring
up new phenomena that can hopefully prove equally
fascinating and sustain, if not expand, the graphene boom.
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Nanotechnology, Sungkyungkwan University, Suwon 440-746, Korea.
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and Related Application”, Acc. Res, vol. 46, pp. 2329-2339, 2013.
[3] A.K. Geim and K.S. Novoselov, “The Rise of Graphene,” Nat. Mater.,
6, 183-197 (2007).
[4] Ismach, et al., “Direct Chemical Vapor Deposition of Graphene on
Dielectric Surfaces”, ACS. Nano. vol. 10, pp. 1542-1548, 2013.
[5] HUI Pak Ming; An Introduction to Graphene and the 2010 Nobel
Physics, Chinese University of Hong Kong.
[6] C. Rao, Ajay Sood; Graphene: Synthesis, Properties, and Phenomena.
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Characterization and Applications.
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