Carbon Nanotubes: Synthesis and Applications

Birck Nanotechnology Center Nanoscale Transport Research Group 1

ECET499 Guest Lecture

Sungwon S. Kim, Ph.D.Visiting Assistant Professor

Birck Nanotechnology Center and School of Mechanical EngineeringPurdue University

March 4th, 2010

Carbon Nanotubes: Synthesis and Applications


Overview

• Nanotechnology

• CNT Synthesis

• CNT Applications

• My Perspective


Nanotechnology

• Study of materials and phenomena at nanoscale

• National Nanotechnology Initiative (NNI)– Launched in 2001 to coordinate research activities

• Birck Nanotechnology Center– $58 million facility opened in 2005

– 187,000 ft2 of space, 25,000 ft2 cleanroom

– Over 45 faculty members and 145 students


Nanotechnology


Nanotechnology• Carbon nanotubes (CNTs)

Diamond Graphite

C60

Carbon chain

C70 CNThttp://www.seed.slb.com/en/scictr/watch/fullerenes/index.htm


Carbon Nanotubes (CNTs)• Timeline

1985 Discovery of Fullerenes R. E. Smalley et al., Nature, 318, 162 (1985)

1991 Discovery of MWNTs S. Iijima et al., Nature 354, 56 (1991)

1992 Conductivity of CNTs C. T. White et al., Phys. Rev. Lett. 68, 631 (1992)

1993 Structural rigidity of CNTs D. Tománek et al., Z. Phys. D 27, 93 (1993)

1993 Synthesis of SWNTs S Iijima, T Ichihashi et al. Nature, 363, 603 (1993)

1995 Nanotubes as field emitters R. E. Smalley et al., Science 269, 1550 (1995)

1996 Ropes of SWNTs R. E. Smalley et al., Science 273, 483 (1996).

1997 Quantum conductance of CNTs C Dekker et al., Nature, 386, 474 (1997)

1997 Hydrogen storage in CNTs M J Heben et al., Nature, 386, 377 (1997)

1998 CVD synthesis of aligned CNT films Z F Ren et al., Science, 282, 1105 (1998)


Carbon Nanotubes (CNTs)• Timeline

2000 Thermal conductivity of CNTs D. Tománek et al., Phys. Rev. Lett. 84, 4613 (2000)

2000 Macroscopically aligned CNTs P. Poulin et al., Science 290, 1331 (2000)

2001 Intrinsic superconductivity of CNTs H. Bouchiat et al., Phys. Rev. Lett. 86, 2416 (2001)

2001 Integration of CNTs for logic circuits P. Avouris et al., Science 292, 706 (2001)

2003 Ballistic CNT field effect transistor H. Dai et al., Nature 424, 654 (2003)

2004 Nanotube molecular transporter H. Dai et al., JACS, 126, 6850 (2004)

2006 Nanotube-based sensor M. Strano et al. Science 311, 508 (2006)

Recommended review book: Carbon Nanotubes: Synthesis, Structure, Properties, and Applicationsby M. S. Dresselhaus, G. Dresselhaus, and P. Avouris


Carbon Nanotubes (CNTs)• Structure

– Formed from the hexagonal graphene carbon structure

– Can form single-wall (SWNT) or multi-wall (MWNT) structures

– Ends (tips) can be open or closed (capped)

– High aspect ratio (length = ~1000 x diameter)


Carbon Nanotubes (CNTs)• Properties

– Mechanical: Young’s modulus ~1 TPa (5X steel) (Treacy et al. 1996)

– Electrical: Metallic or semiconductor behavior, depending on wall structure of SWNTs, and high conductivity

– Thermal: Room-temperature thermal conductivity 3000 W/mK (8X copper) - similar to diamond

– Chemical: high storage capacity


Overview

• Nanotechnology

• CNT Synthesis


• My Perspective


CNT Synthesis• Heterogeneous catalysis

– Carbon atoms: gas to solid

– Catalyst precursor metal deposition• E-beam evaporation at 7x10-7 Torr

• 20nm Cr underlayer used for adhesion and prevention of catalyst poisoning

• Varying Ni catalyst thicknesses: 5nm, 10nm, 20nm

SiCr

Ni


CNT Synthesis• Fe/dendrimer catalyst (wet chemistry based)Fe3+/G4-NH2composite

Fe2O3 nanoparticles

Amama, et al., 2006, "Dendrimer-templated Fe nanoparticles for the growth of single-wall carbon nanotubes by plasma-enhanced CVD", Journal of Physical Chemistry B, Vol.110, pp. 10636-10644.

AFM images of Fe2O3 nanoparticles


MPCVD System

1.5kW and 2.5GHzMicrowave generator

Dual wavelengthpyrometer

Vacuum chamber

75 mm of stage translation

Seki Technotron Corp.AX5200 Series

H2 – 1000cm3/minCH4 - 10cm3/min

DC bias:0 – 600 V; 0 – 1.7 A

Stage temperature control with heating

up to 1000˚C


MPCVD System

Plasma

Suceptor

RF Power Supply

Pump

CH4 H2 N2

Microwave Generator

Puck

Cooling Water Line

Loading Window

Mass Flow Controllers


CNT Synthesis• Growth process

– Samples placed on molybdenum puck

– Chamber evacuated to 0.7 Torr for 5 min.

– Supplied with H2 at 50 sccm and 10 Torr

– Susceptor temperature set to 700˚C

– Plasma ignited at 500W for 2 min.

– Supplied with CH4 at 10 sccm introduced for 10 min.

Nanoparticle aggregation

Si(100)

SiO2

Ni or Fe film deposition

Anneal @ 700oC H2

Nanoparticle aggregation

Si(100)

SiO2

Ni or Fe film deposition

Anneal @ 700oC H2


CNT Synthesis


SiO2

Ti layer

Fe2O3nanoparti

cles

CNT Synthesis

Fe Ni Co


CNT Synthesis

100 nm

10 nm

10 nm

200 nm

250°C, 0V 900°C, 0V

250°C, 0V

900°C, 0V 250°C, 0V 900°C, 0V


Effects of Inlet Gas Compositionon MWCNT Diameter

0 5 10 15 200

10

20

30

40

50

60Di

amet

er [n

m]

Inlet CH4 Volume Fraction [%]

20nm Ni Catalyst 10nm Ni Catalyst 5nm Ni Catalyst

Garg, Kim et al., “Effects of Feed Gas Composition and Catalyst Thickness on Carbon Nanotube and Nanofiber Synthesis by Plasma Enhanced Chemical Vapor Deposition”, Journal of Nanoscience and Nanotechnology, 2008.


0 5 10 15 200

10

20

30

40

50

60Di

amet

er [n

m]

Ni Catalyst Thickness [nm]

5.9% CH4 11.1% CH4 20% CH4

Effects of Catalyst Layer Thicknesson MWCNT Diameter

Garg, Kim et al., “Effects of Feed Gas Composition and Catalyst Thickness on Carbon Nanotube and Nanofiber Synthesis by Plasma Enhanced Chemical Vapor Deposition”, Journal of Nanoscience and Nanotechnology, 2008.


Overview

• Nanotechnology

• CNT Synthesis


• My Perspective


CNT Applications• Biosensor material

– Enzymatic biosensors: immobilization of enzyme on CNTs

– Glucose / glucose oxidase• Electrons formed and collected amperometric

e-

glucosegluconicacid

Pt

Schematic diagram of the glucose/glucose oxidase reaction (adapted from Sotiropoulou and Chaniotakis, 2003).


CNT Applications• Integration of CNT sample with PDMS cell


Fluorescence intensity result for BSA-FITC immobilized Sample #1 - #3

0 100 200 300 400 500 600 700 800 900 10000

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Num

ber o

f Pix

els

Fluorescence Intensity [A.U.]

Sample #1 - autofluorescence check - 1sec exp Sample #1 - FITC BSA - 1 sec exp Sample #2 - autofluorescence check - 1sec exp Sample #2 - FITC BSA - 1 sec exp Sample #3 - autofluorescence check - 1sec exp Sample #3 - FITC BSA - 1 sec exp

Sample 1

Sample 2

Sample 3

-100V Bias

Kim et al., “Effects of Carbon Nanotube Structure on Protein Adsorption”, Proceedings of International Mechanical Engineering Congress and Exposition 2005, IMECE2005-81391, Orlando, Florida, USA.

Protein Adsorption on CNTs



10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

10 μm

0V -100V -200V -300V

250 °C 550 °C

700 °C 900 °C


Characterization: SEMs• Estimation of CNT surface area

d s

h


Characterization: Raman Spectroscopy

1000 1200 1400 1600 1800 2000

0

500

1000

1500

2000

2500

3000

3500 0V, 250oC

Inte

nsity

[A.U

.]

Raman Shift [cm-1]1000 1200 1400 1600 1800 2000

0

1000

2000

3000

4000

5000

6000

7000 0V, 550oC

Inte

nsity

[A.U

.]

Raman Shift [cm-1]

1000 1200 1400 1600 1800 2000

0

2000

4000

6000

8000

10000

12000

Raman Shift [cm-1]

0V, 700oC

Inte

nsity

[A.U

.]

1000 1200 1400 1600 1800 2000

0

2000

4000

6000

8000

10000 0V, 900oC

Inte

nsity

[A.U

.]

Raman Shift [cm-1]

D-band peak at around 1300 cm-

1 (amorphous carbon)

G-band peak at around 1600 cm-

1 (well graphitized structure)

Intensity of the G-band relative to the D-band (IG/ID) calculated to assess quality of CNTs (Amama et al.,

2007, Eklund et al., 1995)


Current per CNT Area vs Raman

0.3 0.4 0.5 0.6 0.7 0.8

0.0

1.0x10-8

2.0x10-8

3.0x10-8

4.0x10-8

5.0x10-8 0V Bias -100V Bias -200V Bias -300V Bias

Curre

nt p

er C

NT A

rea

[A/m

m2 ]

IG/ ID RatioKim et al., 2009, “Preferential Biofunctionalization of Carbon Nanotubes Grown by Microwave

Plasma-Enhanced CVD”, submitted to Journal of Physical Chemistry C.


Protein Adsorption on CNTs• Demonstration of successful protein adsorption

• Nanostructure found to profoundly affect degree of protein adsorption– SEM/TEM/Raman

– Cyclic voltammetry

More defect sites and higher levels of amorphous carbon lead to better protein adsorption (higher negative bias voltage, lower calcination temperatures)

Large CNT area, large number of defect sites per CNT area is best


CNT Applications• Vapor chambers

– Phase change phenomena

– Wicking of working fluid

– Micrometer sized mesh

BULK FEEDING WICK

METALLIZED CNT EVAPORATOR

Kim, Weibel et al., 2010, “Thermal Performance of Carbon Nanotube Enhanced Vapor Chamber Wicks”, submitted to 14th International Heat Transfer Conference.


CNT Applications• Why CNTs?

– Good thermal interface characteristics

– High inherent thermal conductivity

– Wicking capability• Thinning out of liquid layer for improved evaporation

Substrate

LiquidCNTs



Vapor Chamber Wicks• Integration of copper mesh with Cu-Mo-Cu

substrate

• Catalyst metal deposition

• Growth of CNTs in MPCVD



Vapor Chamber Wicks(a) (b)

(c) (d)



Vapor Chamber Wicks


Vapor Chamber Wicks


• Thermal performance


Vapor Chamber Wicks• Thermal performance

– Effective in dissipating upwards of 500 W/cm2 at low levels of superheat without any observed dryout or CHF

– Positive bias, nominal thickness of Cu coating strongly influence level of superheat and wick thermal resistance

denser growth of CNTs, thicker Cu coating leading to better performance


Overview

• Nanotechnology

• CNT Synthesis


• My Perspective


My Perspective• Mechanical engineering

– Ph.D., Purdue University, 2008

– M.S., KAIST, 2002

– B.S., Korea University, 2000

• Engineering devices using CNTs– Performance is driven by structure

– Ability to control structure

Growth Parameters CNT Structure Function


My Perspective• Challenges

– Mass production

– Characterization of properties

– Increased control over geometry

– Optimization of growth parameters

– Integration with engineering devices

Growth Parameters CNT Structure Function


Thank you!!

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Carbon Nanotubes: Synthesis and Applications

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