4. • Graphene can be described as a one atom thick layer of graphite.
• It is two dimensional crystal.
• Sp2 hybridized carbon atoms are densely packed in atomic scale.
• It is the basic structural element of other allotropes of carbon
What is Graphene?
4.
6. • Firstly in 1859 Benjamin Bordie was introduced highly lamellar structure.
• In 1916 structure of graphite solved by V. Kohlschutter & P. Haenni.
• Theory was explored in 1947 by P. Wallace.
• First patents pertaining to the production of graphene was filled in
2002 entitled, “Nano-scaled Graphene Plates”.
• Two years later, in 2004 Andre Geim and Kostya Novoselov at
University of Manchester extracted single-atom-thick crystallites from
bulk graphite.
• Geim and Novoselov received several awards for their pioneering
research on graphene, specially in 2010 by Nobel Prize in Physics.
6.
8. • It is two dimensional network of carbon atom
• These carbon atoms are bounded within the plane by strong
bonds into a honeycomb array comprised of six membered rings.
• Stacking of this layers on top of each other 3-dimensional
graphite crystal is formed.
• It is basic structural element of all carbon allotropes.
• It is an sp2 orbital hybridization with 3σ and 1π bond
• Atomic thickness is about 0.345nm
• Stability
8
10. • Micromechanical cleavage
• Epitaxial growth on silicon carbide substrate
• Chemical reduction of graphene oxide
• Exfoliated Graphene
• Epitaxial growth on metal substrate
• Pyrolysis of Sodium Ethoxide.
• From Nanotubes
• CO2 reduction method
• From Graphite by Sonification
10
11. 1. Micromechanical Cleavage:
• Simplest Method
• Graphite rubbed across flat surface
• Low Yield Process
2. Epitaxial Growth on SiC Substrate:
• Heating process
• Opposite to Mechanically exfoliated
• Expensive
3. Chemically Exfoliation of Graphene by Graphite:
• Attached oxygen-rich functional groups
• Immersed in water
• Deposit Graphene oxide
• Reduced it to Graphene
11
13. • Chemically the most reactive form of carbon,
• Only form of carbon in which each single atom is in exposure for
chemical reaction from two sides (2D structure)
• Carbon atoms at the edge of graphene sheets and various types of
defects within the sheets increases the reactivity.
• Highest ratio of edgy carbon.
• Burns at very low temperature i.e. 350 ºC.
• One atom thick sheet is 100 times more reactive than thicker sheet.
13
15. • It is zero-overlap semimetal with very high electrical conductivity
• Electrons are able to flow through graphene more easily than through even copper
• Electrons travel through graphene as if they carry no mass, as fast as just one
hundredth that of speed of light.
• High charge carrier mobility, for which values of 2,00,000 cm2/V.s
• Resistivity is 10-6 Ω.
15
17. • Strongest material ever discovered
• Tensile strength 130GPa compared to A36 structural steel with 400MPa.
• Harder than diamond and about 200 times harder than steel.
• Very light - 0.77mg/m2 i.e 1m2 paper is 1000 times heavier
• It is stretchable up to 20% of its initial length.
• AFM test shows that graphene sheets with atomic thickness 2-8 nm had spring
constant 1-5N/m and Young’s modulus 0.5 – 1TPa
17
19. • It is perfect thermal conductor.
• Its thermal conductivity is much higher than all other carbon structure at
room temperature i.e. 5000 W/mK
• Graphite shows thermal conductivity about 5 times smaller i.e. 1000 W/mK
• Graphene based electronic device even on a substrate thermal
conductivity reaches 600 W/mK
• The Ballistic thermal conductivity of graphene is isotropic.
19
20. • Despite it is one atom thick it is still visible to naked eye.
• Due to its unique electronic properties, it absorbs a high 2.3%
of light that passes through it.
20
Photograph of graphene in transmitted light. This one
atom thick crustal can be seen to naked eye because it
absorbs approx 2.6% of green light and 2.3% of red light
21. • In Paint industry:
As it protects and conducts it means it can be used in
advanced paints to reduce corrosion and to increase energy efficiency
• In Aircraft techniques and vehicles
Due to light weight, high tensile strength and hardness it can
be used in aircraft and cars.
21
22. • Biomedical
• Graphene could soon be used to analysis
DNA at record breaking pace
• Sending molecules through tiny slit in
graphene sheet
22
23. • Integrated Circuits
• Due to high carrier mobility and low noise, allow
to used as channel in a field effect transistor
•Processor using 100GHz transistor on 51mm
graphene sheet
•Graphene based integrated circuit handled
frequencies upto 10GHz
•Transistor printed on flexible plastic that operate
at 25GHz
23
24. • Optical Electronics
• High Electrical conductivity and high
transparency make it candidate for transparent
conducting electrode
• Its medical strength and flexibility are
advantageous compared to indium-tin-oxide,
which is brittle
•So it would be work very well in optoelectronic
24
25. • Solar cells
•The transparent, conductive and ultrathin
graphene films are fabricated from exfoliated
graphene oxide, followed by thermal
reduction
•The obtained films exhibits high conductivity
and transparency of more than 70% over
2000-3000 nm
25
26. • Energy Storage Devices
• Due to extremely high surface area to mass
ratio of graphene, it is used in conductive
plates of superconductors
• It could be used to produce super capacitor
with greater energy storage density.
26
27. • Potable water by desalination:
• Arrange thin monolayer graphene sheet in cross with each
other
• It allows only water molecule through to it and remain salt
behind it.
• It depends upon the pressure and size of the pore also
27
A) By arrangement of sheets
28. 28
• New Method – CDI (Capacitive deionization technology)
• No secondary pollution and cost effective
• Energy efficient
• Uses graphene like nanoflakes as electrode
B) By CDI
29. • Alcohol distillation:
• Arrange Graphene oxide sheets in such a way that between them
there is room for exactly one layer of water molecule.
• if another molecule tries to escape, Graphene capillaries either
shrinks or clogged with water
•It blocks Helium gas also
29
30. • Sensor:
• Able to the detection of low concentration, toxic, and explosive
chemical vapors and gases.
•Sensors capable of detecting chemical vapor concentration part per
billion.
•CMG film attached with oxygen functional group on it.
• reduced chemically or thermally and provide knob with which to tune
the sensor response.
•These devices are then exposed to pulses of chemical vapors and
resulting change in material is measured.
30
32. Some other Applications:-
• Graphene Nano ribbons
• IR detectors
• Piezoelectric materials
• Composite materials
• Liquid cells for Electron Microscopy
• Optical Modulators
• Thermal Management materials.
32
33. 33
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• S. Stankovich et al., “Synthesis of Graphene-based Nanosheets
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3137–3140 (2008); J.T. Robinson et al., “Wafer-scale Reduced Graphene Oxide Films for
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•0
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