Chemistry of Graphene and Its Technological Applications-Prof.loh

8/13/2019 Chemistry of Graphene and Its Technological Applications-Prof.loh

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The Uniqueness of Carbon

ONE OF THE MOST FLEXIBLE ELEMENTS

Organic chemistry derives its richness

from this chemical flexibility of carbon

-Carbon allotropes: Diamond, Graphite, Fullerene,

Carbon nanotube, and now GRAPHENE


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Carbon materialsThe origin of many

forms of carbon

Wrapping (10,0)SWNT (zigzag)-

(Animation)


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uAndre Geim in New Scientist. Graphene is stronger and stiffer than diamond,

yet can be stretched by a quarter of its length, like rubber.

Its surface area is the largest known for its weight.

Geim and his colleague (and former postdoctoral assistant) Konstantin

Novoselov first produced graphene in 2004 by repeatedly peeling away graphite

strips with adhesive tape to isolate a single atomic plane.

2010 Nobel Prize in Physics: Graphene


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C*: 1s2

, 2s1

, 2px1

, 2py1

, 2pz1

Large heat and electrical conduction in

Carbon materials help solve the problem of

energy waste


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The Manchester team in 2008 created a 1-nanometer graphene transistor,

only one atom thick and 10 atoms across

-smaller than the smallest possible silicon transistor

-represent the absolute physical limit of Moores Law governing the shrinking size

and growing speed of computer processors

2008


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Superior Mechanical Properties Stretchable Electronics

Super-friction

Super-elastic

Super-conductive

Future electronics

SKKU, Nature 2009, 457, 706.


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Carbon Silicon

Si-SiO2 interface engineering

sp2 hybridization:120o

sp3 hybridization: 109o

Dangling bonds at Si (110)

Doping of Si


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The Uniquenes of Graphene

ULTRATHIN SHEETS WHICH CAN MEDIATE MULTIPLE INTERCATIONS


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Doping and functionalization of graphene

B or N-doped

H or K-doped

F4-TCNQ-doped

Biomolecules-adsorbed

graphane

Small molecules on graphene

Approaches: 1. covalent bonding; 2. p-p stacking; 3. adsorbing

Graphane & fluorographene


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How to D. I. Y. Graphene?

DIY Graphene:

1. Attach a graphite flake to about six inches (15 cm) of plastic

sticky tape with tweezers

2. Fold the tape right next to the flake so that you sandwich it

between the tape's sticky sides

3. Press down gingerly to get a good seal and then peel the

tape apart slowly enough so that the graphite cleaves

smoothly in two

4. Repeat the above steps 2 and 3 for many rounds until the

duplicate flakes looks shinier, which means the peeling has

exposed an atom-smooth layer

5. Transfer the sample onto SiO2/Si substrate for checkingunder optical microscopy and device fabrication


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Chemical Vapor Deposition Growth of

Graphene on Copper Catalyst

Five steps occurduring generic CVDprocesses:

Reactants pumpedthrough reactor.

Reactants diffuse acrossboundary layer to surface.

Reactants adsorb onsurface (adatoms).

Surface reactions; pos.formation of islands orclusters.

Pos. surface diffusion ofadatoms.

Diffusion of by-productsaway from surface.

Science 324, 2009, 1312


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Applications of large-area graphene

Touch-screen panel Solar cell


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The Chemists way: how graphite can be

exfoliated to produce graphene oxide

Angew. Chem. Int. Ed. 2010, 49, 227


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Reduction by hydrazine

S. Stankovich, D. A. Dikin, R. D. Piner, K. A. Kohlhaas, A.

Kleinhammes, Y. Jia, Y. Wu, S. T. Nguyen and R. S. Ruoff,

Carbon, 2007, 45, 15581565.


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OC

CH2OO

H

H

O

O

H

O

HOH 2

C

OH2C

HH

OO

HO

H CH2O

HN

OC

NH2

H2NH2N

H2N

H2N

NH2

NH

NH2

H2N

O

NH2

HN

CH2CH2On

=

CO= Cy7

b

KB

U87MG

4T1

30min 1h 6h 24h

a

Nano Graphene oxide can be used to deliver drugs , and can be used

for cancer therapy


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In vivo photothermal therapy study

using intravenously injected

Nanograpnene oxide

EXP by

Suzhou U,

CHINA


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Graphene Oxide as Green Catalyst:

Metal Free, Highly Selectivity, Recyclable.

D. R. Dreyer, H.-P. Jia, C.W. Bielawski,Angew. Chem. Int. Ed. 2010, 49, 6813 6816.

Oxidation Reaction

Hydration Reaction

graphene oxide has been found to catalyze

alcohol and alkene oxidations as well as alkyne hydrations


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The possible mechanism for the oxygen activation:


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HIGHLY SENSITIVE GAS SENSORS

WORLDS THINNEST BALLOON

MECHANICAL PROPERTIES - IMPERMEABLE MEMBRANE


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Impermeable Atomic Membranes from

Graphene Sheets

Bunch, Nano Lett., 2008,8 (8): 2458-62


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MIX-AND-MATCH HYBRIDS

Polymers have been combined with other plastics to form blends,

mixed with talc and clay to give filled systems,

and extruded and molded with fibers and otherreinforcements to yield composite and hybrid materials.

The superiority of graphenes over carbon nanotubes

as reinforcements stems from

easy access to the graphitic precursor material,

the cost, the scalable method, and its orientation flexibility (morphology).


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Comption Adv. Mater. 2010, 22, 47594763

Crumpled Graphene Nanosheets as

Highly Effective BarrierProperty Enhancers


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Graphene for Energy (1)

Graphene to replace ITO for solar cell

uGreen energy

Organic solar cell

Dye sensitized solar cell


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Graphene for Energy (2)

Graphene

Graphene supercapacitor

Graphene battery

2630 m2/gram

85.6 Wh/kg at room temperature and136 Wh/kg at 80 deg C

Specific energy density


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Graphene for EnvironmentTiO2/graphene Composites for Photodegradation

of Methyl Orange

Photocatalytic degradation of dyes

over graphene-gold nanocompositesunder visible light irradiationChem. Commun., 2010, 46, 6099

Water splitting/hydrogen

evolution/Oxygen evolution catalysts


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Transistor

Quantumelectronics Gas sensor

PhotodetectorElectromechanical

Resonators

Mode-locked laser


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The carbon laboratory @ NUShttp://staff.science.nus.edu.sg/~thecarbonlab/index.html

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Chemistry of Graphene and Its Technological Applications-Prof.loh