Carbon Nanotubes: Synthesis and Functionalization

L. ValentiniL. Valentini

Materials Engineering Centre, INSTM, UdR Perugia Materials Engineering Centre, INSTM, UdR Perugia -- UniversitUniversitààdi Perugia, di Perugia,

Loc. PentimaLoc. Pentima Bassa Bassa -- TerniTerniWebsite: Website: http://www.unipg.it/materialshttp://www.unipg.it/materials

NanoTech Lab @ TERNISurfaces, Thin films & Nanostructures

STNSTN

Dr.ssa Ilaria Armentano

Dr. Francesco Mengoni

Dr.ssa Federica Meloni

Prof. J. M. Kenny

Dr. Luca Valentini

Unique Properties of Carbon NanotubesUnique Properties of Carbon Nanotubes

Graphene sheet SWNT

• Size: Nanostructures with dimensions of ~1 nm diameter (~20 atoms around the cylinder)

• Electronic Properties: Can be either metallic or semiconducting depending on the diameter or orientation of the hexagons

• Mechanical: Very high strength and modulus. Good properties on compression and extension

• Heat pipe and electromagnetic pipe• Single nanotube spectroscopy yields structure• Many applications are being attempted worldwide

Applications for NanotubesApplications for NanotubesScanning tips and ElectronicsScanning tips and Electronics

S.J. Tans et al. Nature, 393, 49 (1998)

Field Emitter

TransistorSTM/AFM tipsSTM/AFM tipsDirect Analysis of DNADirect Analysis of DNASemiconductor devicesSemiconductor devicesField EmittersField Emitters

New Materials

Fullerene C60 inside nanotubes

Imaging biological molecules

AFM image of Immunoglobulin G resolved by nanotube tips

Challenges for Carbon Nanotube Research

• Control synthesis process to produce tubes with same diameter and chirality

• Until control of synthesis process is achieved, develop effective separation methods:

metallic from semiconductingby diameterby chirality

• Develop method for large-scale, cheap synthesis• Improve nanotube characterization and

manipulation • Develop commercial scale applications

Defects in CNTsDefects in CNTs1Point defects such as Point defects such as

vacanciesvacanciesTopological defects caused Topological defects caused by forming pentagons and by forming pentagons and heptagons e.g. 5heptagons e.g. 5--77--77--5 5 defectdefectHybridization defects Hybridization defects caused due to caused due to functionalization

Ibridizzazione sp31

functionalization

10 nm

1Ref: S Namilae et. al. (2001)

Defects in CNTsDefects in CNTs

1200 1400 1600 1800

SWNTs

Inte

nsity

[arb

. uni

ts]

Wavenumber [cm-1]

F. Mercuri et al., J. Phys. Chem. B (submitted)

Role of Interfaces in CompositesRole of Interfaces in Composites

Critical issues in nanotube compositesCritical issues in nanotube composites–– DispersionDispersion

Load transfer effected by interface characteristicsLoad transfer effected by interface characteristicsInterfaces further affect electrical propertiesInterfaces further affect electrical propertiesInterface Interface Bounding surface with physical / Bounding surface with physical / chemical / mechanical discontinuitychemical / mechanical discontinuity–– Strengthening of interfaces in conventional Strengthening of interfaces in conventional

compositescompositesChemical reactionChemical reactionSurface asperities on fiberSurface asperities on fiber

In CNT composites In CNT composites chemical attachmentschemical attachments

Experimental approach: Plasma TreatmentElectric Fields

π stacking• Techniques

TGAFT-IR (KBr)UV-Vis SEMTEM

Functionalization of CNTsFunctionalization of CNTs

Plasma deposition of fluorinated carbon films on single-walled carbon nanotubes

1000 2000 3000 4000

Tran

smitt

ance

[arb

. uni

ts]

Wavenumber (cm-1)

SWNTs

10 nm 5 nm

1000 2000 3000 4000

F-SWNTs

C=CCF

Tras

mitt

ance

[arb

. uni

ts]

Wavenumber [cm-1]

10 nm

5 nm

PECVD Fluorination of SWNTs (TGA)

200 400 600 80030

40

50

60

70

80

90

100

In Air

Res

idua

l Mas

s [%

]

Temperature [°C]

SWNTs F-SWNTs 25°C F-SWNTs 200°C

200 400 600 800

60

70

80

90

100 In Nitrogen

Res

idua

l Mas

s [%

]

Temperature [°C]

F-SWNTs 25°C SWNTs F-SWNTs 200°C

STM

200 400 600 8000

20

40

60

80

100

120

140

160

CF4

COF2

CO2

DTG

[µg/

µgi*m

in]

Temperature [°C]

SWNTs F-SWNTs 25°C F-SWNTs 200°C

F-SWNTsSWNTs

500 1000 1500 2000 2500 3000 3500 4000

NH

NH2

Tras

mitt

ance

[arb

. uni

ts]

Wavenumber [cm-1]

DETA F-SWNTs+DETA

1000 1050 1100 1150 1200 1250

CN Region

Tras

mitt

ance

[arb

. uni

ts]

Wavenumber [cm-1]

DETA F-SWNTs+DETA

Sidewall Functionalization of SWNTsthrough CF4 Plasma Treatment and Subsequent Reaction with Aliphatic

Amines (DETA)

- F +

HF

25°C

RNH-

L. Valentini et al., Chem. Phys. Lett.(accepted)

TGA

500 1000 1500 2000 2500 3000 3500 4000

Tras

mitt

ance

[arb

. uni

ts]

Wavenumber [cm-1]

F-SWNTs/Butilammina

500 1000 1500 2000 2500 3000 3500 4000

Stretching C-H

bending N-H

Stretching C-Nbending N-H

16103370

3290

Tras

mitt

ance

[arb

. uni

ts]

Wavenumber (cm-1)

FTIR

- F +25°C

HF

SWNTs/BuF-SWNTs/Bu

F-SWNTs and Subsequent Reaction with Butylamine

200 400 600 8000.1

1

10

100

Butylamine+F-SWNTs

F-SWNTs

Butylamine

Res

idua

l Mas

s [%

]

Temperature [°C]

- RNH

“An overwhelming Butylamine fraction is

distributed over SWNTssidewalls. These molecules

are chemically attached there.”

Chemical Gating and Photoconductivity of CF4 Plasma Functionalized Single-Walled Carbon Nanotubes by Butylamine

-10 -5 0 5 109,6x10-7

9,6x10-7

-7

9,7x10-7

9,8x10-7

9,8x10-7

F-SWNTs

I sd [A

]

Vg [Volt]

-10 -5 0 5 102,386x10-4

2,388x10-4

2,390x10-4

2,392x10-4

2,394x10-4SWNTs

I sd [A

]

Vg [Volt]

9,7x10 9,0x10I

-10 -5 0 5 108,0x10-10

8,5x10-10

-10

9,5x10-10

1,0x10-9

1,1x10-9

Butylamine+F-SWNTs

sd [A

]

Vg [Volt]

0.0 3.5x103 7.0x103 1.1x104 1.4x104

2.0x10-8

2.2x10-8

2.4x10-8

2.6x10-8

2.8x10-8Butylamine+F-SWNTs

I SD [A

]

Time [s]

L. Valentini et al., J. Appl. Phys. (submitted)

200 400 600 800

0

20

40

60

80

100

0.00

0.02

0.04

0.06

0.08

APTES

T/°C

Templated Assembly of 3-Aminopropyltriethoxysilane at the

Surface of F-SWNTs

- F +

HF 200 400 600 800

0

20

40

60

80

100

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

0.06

T/°C

APTES+SWNTs

200 400 600 80030

40

50

60

70

80

90

100

-0.001

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

F-SWNTs+APTES

T / °C

Selective Functionalization of Metallic Single-Walled Carbon Nanotubes by Conducting Dendrimer (poly(amidoaminepoly(amidoamine)) PAMAM PAMAM

functionalizedfunctionalized withwith naphthalenediimdenaphthalenediimde groupsgroups))

100 120 140 160 180 200

176 (1.43)(18,0)

176 (1.43)(18,0)

165 (1.49)(15,6)

162 (1.53)(14,8)

150.3 (1.65)(12,12)

146,8 (1.69)(19,4)

Inte

nsity

[arb

. uni

ts]

Wavenumber [cm-1]

SWNTs PAMAMC polymer-coated SWNTs

20 nm20 nm

20 nm

FET PAMAMC/SWNTs

-10 -5 0 5 100.0

1.0x10-11

2.0x10-11

3.0x10-11

4.0x10-11

5.0x10-11

6.0x10-11

I sd [A

]

Vg [V]

SWNTs (Lsd

16 µm and W 100 µm)

S.J. Tans et al. Nature, 393, 49 (1998)

-10 -5 0 5 103.2x10-7

3.3x10-7

3.4x10-7

3.5x10-7

3.6x10-7

I sd [A

]

Vg [V]

PAMAMC polymer-coated SWNTs-FET device

-20 -15 -10 -5 0 5 10

4.5x10-5

4.5x10-5

4.5x10-5

4.5x10-5

I sd [A

]

Vg [V]

SWNTs (Lsd 8 µm and W 100 µm)

GrowthGrowth of of selfself--assembledassembled CNTsCNTs bybyPECVDPECVD

Q

Substrato Si

Q + Plasma CH4

CNT

Ni

Pt

Influence of Ni Catalyst LayerNi = 20nmNi = 20nmNi = 5nmNi = 5nmNi = 3nmNi = 3nm

Influence of Pulsed Plasma Mode10-1s10-3s 10-2s

L. Valentini et al., Chem. Phys. Lett. 387 (2004) 356

Electrically Switchable Carbon NanotubeHydrophobic Surfaces

M. Grujicic et al., AppliedSurface Science 206 (2003)

167

R. Pati et al., APL 81 (2002) 2638

500 1000 1500 2000 2500 3000 3500 4000

(d,e)(c)(b)

(a)

Abs

orba

nce

[arb

. uni

ts]

Wavenumber [cm-1]

FTIR spectra obtained under exposure to H2O without (a) an electrical field and at different frequencies (b) 1 Hz, (c) 100 Hz, (d) 1

KHz and (e) 1 MHz (1V ac excitation wave).

The IR spectra obtained at different frequencies under exposure to H2O show that the transparency tends to decrease when increasing the applied frequency. The results obtained suggest that the main contribution to the

interaction between water vapor molecules and the nanotube is associated to adsorbate-dipole/nanotube-dipole interactions.

L. Valentini et al., Diamond and Related Materials 14 (2004) 121.

The NanoChan ProjectThe NanoChan ProjectNano Channel Template: fabrication of a photovoltaic device.

TWO nanotechnologies involved:

1. Nanochannels built in the self-assembled CNTs template with regular and uniform pattern

2. Carbon nanotubes grown by self-assembling on Pt electrodes

Optimize CN properties in order to use themas charge collectors between an activemedium and the readout electronics and study the coupling

Optical Window

R/O electronics

Basic idea

NanotubeNanotube arrayarray

NanoNano--heterohetero--junctionsjunctions

Si

Ligth

Channels for charges

transportation

n-type a-C:H(F) nanochannel

p-type CNTs array

Plasma CF4

Substrate Si

-3 -2 -1 0 1 2 31E-101E-91E-81E-71E-61E-51E-41E-3

a-C:H:F/CNTsCur

rent

[A/c

m2 ]

Voltage [V]

CONCLUDING REMARKSCONCLUDING REMARKS

☺ Research on nanotubes and nanowires show much interesting science with potential for applications☺ Attaching chemical groups to the sidewall of CNTs to modify the properties as needed for applications

Chemical modification of the sidewall may improve the adhesion characteristics of CNTs in a host matrix to make compositesChemical or photosensors

☺ Fluorination of SWNTs with CF4 gas has been shown to attach F covalently to the sidewall☺ Cold plasma approach to functionalization

BUT

Major challenges still exist:- Low material cost, - High durability,- Control of materials properties,- Self-assembly of large numbers of components.

SEM - TEM, Raman, Synthesis of PAMAMProf. S. Russo (Dip. di Chimica e Chimica Industriale, Università di Genova)Dr. Laura Ricco (Dip. di Chimica e Chimica Industriale, Università di Genova)Dr. Jenny Alongi (Dip. di Chimica e Chimica Industriale, Università di Genova)Dr. A. Mariani (Dip. Di Chimica, Universitàdi Sassari)

AcknowledgmentsTGA - FTIRDr. D. Puglia (Dip. di Dip. di Ingegneria Ingegneria CivileCivile e e AmbientaleAmbientale, , Università di PerugiaUniversità di Perugia)Dr. I. Armentano (Dip. di Dip. di Ingegneria Ingegneria CivileCivile e e AmbientaleAmbientale, , Università di PerugiaUniversità di Perugia)Dr. J. Macan (Sveuciliste u Zagrebu)

Funding:Ministry of Education, University and Research through the PRIN, FIRB projectsThe National Consortium of Materials Science and Technology (INSTM)

e-BEAM LithographyDr. G. Pennelli (Dip. di Ingegneria dell' Informazione: elettronica, informatica, telecomunicazioni, Università di Pisa)

Molecular DynamicProf. A. Sgamellotti (Dip. di Chimica, ISTM – CNR, Università di Perugia)Dr. F. Mercuri (Dip. di Chimica, ISTM –CNR, Università di Perugia)