Transcript Hybrids with Graphene

Hybrids with Graphene
for
Optical Limiting Applications
Pramod Gopinath
Indian Institute of Space Science and Technology
Valiamala, Thiruvananthapuram 695 547
IIST…
Annual Photonics Workshop – February 28, 2014
Outline of the talk
●
●
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Graphene – an Introduction
Methods of Graphene Preparation
Characterization of Graphene
Optical Limiting
● Graphene
● Graphene-C60 Hybrid
● Polyaniline-Graphene Hybrid
● ZnO-Graphene Hybrid
● Conclusion
Annual Photonics Workshop – February 28, 2014
2010 Nobel Prize for Physics
for ground breaking experiments regarding the two
dimensional material graphene
Konstantin Novoselov and Andre Geim
Centre for Mesoscience and Nanotechnology and
School of Physics and Astronomy, University of Manchester
Annual Photonics Workshop – February 28, 2014
Graphene Sheet (2 D monolayer of carbon atoms)
Fullerene
0D
Nanotube
1D
Graphite Sheet
3D
A. K. Geim & K. S. Novoselov. The rise of graphene. Nature Materials Vol . 6 ,183-191
(2007)
Annual Photonics Workshop – February 28, 2014
Properties of Graphene

Electronic Properties – High electron mobility (230,000 cm2/Vs)

Thermal Properties - Thermal Conductivity ( 3000 W/mK)

Mechanical Properties – Strength (130 GPa), Young’s modulus (~1.3 TPa)

Optical Properties – 2.3% absorption of visible light

Quantum Hall Effect – minimum Hall conductivity ~ 4 e2/h
Annual Photonics Workshop – February 28, 2014
Preparation of Graphene

Top down approach from Graphite



Micromechanical exfoliation
Creation of colloidal suspensions
Bottom up approach from carbon precursors



CVD
Organic synthesis
Epitaxial growth on insulating substrates
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Preparation of Graphene
Micromechanical exfoliation
Annual Photonics Workshop – February 28, 2014
Preparation of Graphene
Graphite flakes are
combined with
sodium cholate in
aqueous solution
Green and Hersam,
Nano Letters, 9,
4031 (2009)
Annual Photonics Workshop – February 28, 2014
Preparation of Graphene
Roll based production of graphene films on copper foil
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Preparation of Graphene
From Carbon nano tubes
NATURE, Vol , 458, 16 , April (2009)
Annual Photonics Workshop – February 28, 2014
Preparation of Graphene
Oxidation (Hummers’method)
Graphite Oxide
H2SO4/ KMnO4
H2SO4/KClO3
Or H2SO4/HNO3
……………….
H2O
Ultrasonication (exfoliation)
Graphene Oxide
monolayer or few layers
Fuctionalization (for better dispersion)
Chemical reduction to restore graphitic structures
Making composite with polymers
Making composite with polymers
Annual Photonics Workshop – February 28, 2014
Graphene - Characterization
Optical Microscopy
Image of Single, Double and
Triple layer Graphene on Si with
a 300 nm SiO2 over layer
Annual Photonics Workshop – February 28, 2014
Graphene - Characterization
Atomic Force Microscopy
Images of unreduced and chemically
reduced graphene oxide nanosheets
deposited from aqueous dispersions
Annual Photonics Workshop – February 28, 2014
Graphene - Characterization
Flourescence Quenching Microscopy
Image showing G-O single layer deposited on a SiO2 /Si
wafer applying a 30 nm thick fluorescein/PVP layer
Annual Photonics Workshop – February 28, 2014
Graphene - Characterization
Transmission Electron Microscopy
Image of a single layer Graphene membrane
Step from a monolayer to a bilayer
Annual Photonics Workshop – February 28, 2014
Graphene - Characterization
Raman Spectroscopy
D – 1350 cm-1
G – 1580 cm-1
2D – 2700 cm-1
D band – presence of
disorder in atomic
arrangement or edge effect
G band – in plane vibration of
sp2 carbon atoms
2D band – second order
Raman scattering
Annual Photonics Workshop – February 28, 2014
Nonlinear Optical Materials
Saturable Absorbers
which give increased transmittance at high optical intensities or fluences,
and are useful for pulse compression, Q-switching and mode-locking
Optical Limiters
Which give decreased transmittance, and are useful for pulse shaping,
mode locking and for the protection of eyes and sensor focal-plane arrays
Progress in development of Optical limiters with large NLO responses in
carbon-based materials like, graphitic systems, single-walled CNTs,
small π-electron systems like fullerenes, porphyrins and phthalocyanines
Challenge: Development of materials that can be processed as stable
solutions or liquid dispersions that can ultimately be formed into films for
practical applications
Annual Photonics Workshop – February 28, 2014
Optical Limiting
Open aperture Z-scan technique
Sheik-Bahae, M., et al. IEEE J. of Quantum Electron., 26(4): 760-769 (1990).
Annual Photonics Workshop – February 28, 2014
Optical Limiting
Open aperture Z-scan plot
Optical limiting plot
1.0
Tnorm
Tnorm
1.0
0.8
0.8
0.6
0.6
-12
-8
-4
0
4
8
12
1.3x10
z(mm)
T z, S  1 
1

q0 z,0 
11
10
12
6x10
12
Input intensity (W/m2)



t
 ln 1  q0 z,0e dt where q0 ( z,0)   (1  R)I 0 Leff 1  z
2
2
z02 

z0 is the Rayleigh length.
R is the Fresnel reflectance of the sample surface
Leff is given by [1  e L ] 
α is the linear absorption coefficient
L is the thickness of the sample
R. L. Sutherland, Handbook of Nonlinear Optics, second ed., Marcel Dekker, New York, 2003.
Annual Photonics Workshop – February 28, 2014
Annual Photonics Workshop – February 28, 2014
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Graphene – C60 Hybrid
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Graphene-Polyaniline Hybrid
2000 Nobel Prize
Alen Heeger A.J.MacDiarmid H.Shirakawa
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Synthesis of graphite oxide (GO)
Low temperature modified Hummers method
Characterization
45
Graphite
Peak position (cm-1)
Assigned vibrations
1729
C=O stretching
1399
Carboxy C-O stretching
1186
Epoxy C-O-C stretching
1084
Alkoxy C-O stretching
1632
Unoxidized C=C stretching
>3000
O-H stretching
% Absorbance
40
35
15
10
GO
1084
1186
1729
1399
1632
5
500
1000
1500
2000
2500
Wavenumber (cm-1)
3000
3500
Annual Photonics Workshop – February 28, 2014
SEM image
TEM image
nm
2 2nm
Annual Photonics Workshop – February 28, 2014
AFM image
Synthesis of polyaniline-graphite oxide hybrid
In-situ polymerization of aniline in presence of GO
Various compositions : PxGy, (x =proportion of aniline, y= proportion of GO)P4G1, P2G1, P1G1, and P1G2
Annual Photonics Workshop – February 28, 2014
SEM images
Polyaniline
P1G2
AFM
image
500 nm
TEM image
5 µm
HRTEM image
3.2 nm
1 nm
Annual Photonics Workshop – February 28, 2014
Nonlinear optical properties
Sample
β cm
Isat
name
GW-1
GW
cm-2
Annual Photonics Workshop – February 28, 2014
Polyaniline
5.8
2.5
GO
5.5
3.5
P4G1
8
1.5
P2G1
11
0.7
P1G1
13
0.6
P1G2
19
0.4
Polyaniline-phenylene diamine functionalized
reduced graphene oxide hybrids
Synthesis of phenylene diamine modified
reduced graphene oxide (GONH2)
Annual Photonics Workshop – February 28, 2014
TEM image
SEM image
5 µm
Annual Photonics Workshop – February 28, 2014
Synthesis of polyaniline-phenylene diamine modified
reduced graphene oxide hybrid
GONH2 to aniline ratio
1:2
1:1
2:1
Annual Photonics Workshop – February 28, 2014
SEM image
TEM images
Annual Photonics Workshop – February 28, 2014
Remyamol T, Pramod Gopinath, Honey John. Synthesis and nonlinear optical properties of reduced
graphene oxide covalently functionalised with polyaniline. Carbon 59 (2013) 308-314.
β
Isat
cm GW-1
GW
cm-2
Polyaniline
5.8
2.5
GONH2
4.8
3.7
P2NH2G1
12
0.6
P1NH2G1
15
0.5
P1NH2G2
25
0.2
Sample name
Annual Photonics Workshop – February 28, 2014
Covalently grafted polyaniline- reduced graphene oxide hybrid
Synthesis of polyaniline-reduced graphene oxide hybrid
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SEM image
TEM image
Annual Photonics Workshop – February 28, 2014
Remyamol T, Pramod Gopinath, Honey John. Grafting of self assembled polyaniline nanorods on
reduced graphene oxide for nonlinear optical application. Synthetic Metals 185-186 (2013) 38-44.
Optical limiting plots
Open aperture Z-scan plots
β cm
Isat GW
GW-1
cm-2
GO
5.5
3.5
Polyaniline
9.5
2
Polyanilne-g-rGO
20
0.25
Sample name
Annual Photonics Workshop – February 28, 2014
Reduced Graphene oxide-ZnO Hybrid
Reduced graphene oxide –ZnO hybrid is synthesized by two routes:
Hydrothermal Synthesis
Solution precipitation technique
Annual Photonics Workshop – February 28, 2014
Reduced Graphene oxide-ZnO Hybrid
Zn(Ac)2 (1 mmol)
CH3COOH
Polyvinylpyrrolidone
(PVP) (0.05 %)
Zn(Ac)2- PVP complex
Different weight ratios of GO
Dispersed by sonication for
8 h Followed by stirring for
NaOH
16h
ZnO/GO colloid
Stirred at room
temperature for 12 h
(solution precipitation)
S-rGO-ZnO-x
Kept in autoclave at
different temperature for
7 h @ 100oC
(hydrothermal method)
H-rGO-ZnO-x
Annual Photonics Workshop – February 28, 2014
Annual Photonics Workshop – February 28, 2014
IR and Raman spectra of H-rGO-ZnO and S-rGO-ZnO
 Decrease of oxygen functional groups in hybrid
 in both the samples peak at 1730 cm-1
(C=O stretching vibrations of the –COOH groups) is absent
 For S-rGO-ZnO, peak at 1680 cm-1 indicate C=O in conjugation with C=C
 ID/IG ratios 0.94 and 1.03 for H-rGO-ZnO and S-rGO-ZnO
 Restacking of exfoliated graphene sheets are prevented by the
as-grown ZnO nanoparticles
Annual Photonics Workshop – February 28, 2014
 compared to bare ZnO and GO, hybrid shows enhanced
nonlinear optical properties
 photoinduced electron transfer and energy transfer
 For hydrothermally synthesized hybrid, more extended
-conjugation results in enhanced NLO properties
Annual Photonics Workshop – February 28, 2014
Conclusion
Lot of scope for further work in Hybrids as the
optical limiting properties can be enhanced by
suitably modifying the functionalities
Annual Photonics Workshop – February 28, 2014
A word of Gratitude……
Collaborators:
1. Dr. Honey John, Department of Chemistry, IIST
2. Dr. Reji Philip, Raman Research Institute
Research Students:
1. Ms. Remyamol T
2. Ms. Kavitha M K
Annual Photonics Workshop – February 28, 2014
Annual Photonics Workshop – February 28, 2014