This document summarizes carbon nanotube synthesis using chemical vapor deposition (CVD). CVD involves heating carbon precursors like methane or acetylene in a reactor tube to high temperatures where they decompose on catalysts like nickel, iron or cobalt. Single-walled and multi-walled nanotubes can be grown via tip or base growth mechanisms. The document discusses various catalysts, precursors, growth conditions and applications of carbon nanotubes in areas like electronics, sensors and composites due to their excellent electrical, thermal and mechanical properties.

1. SYNTHESIS OF CARBON NANOTUBES BY USING CVD
METHOD
By
JEETENDRA KUMAR
SHRI MATA VAISHNO DEVI UNIVERSITY KATRA (J&K)
To
Dr. PRATHAP HARIDOSS
ASSOCIATE PROFESSOR
IIT MADRAS

2. Carbon Nano Tubes
Contents:
1. Introduction
2. Classification of CNTs
3. Properties & Applications
4. Synthesis methods
5. Precursors
6. Catalysts
7. Catalyst supporters
8. Growth mechanism
9. References

3. Introduction
Carbon nano tubes are allotrope of carbon with
a cylindrical nanostructure or Carbon
nanotubes (CNTs) are rolled up cylinders of
graphene sheets.

4. Classification
Carbon nano tubes
Single walled
carbon nano
tube
(SWCNT)
Multi walled
carbon nano
tube
(MWCNT)
Arm chair
Zigzag
Chiral
Herringbone
Bamboo

5. (a) Armchair, (b) Zigzag, (c) Chiral
Nano tubes

6. Textures of MWCNTs (a) herringbone
texture and (b) bamboo texture
Multi walled carbon
nano tube

7. Properties:-
132,000,000:1 Length-To Diameter Ratio
Diameter of 3 to 9 nm
Lengths in the millimeter range
Efficient electrical conductors
High thermal conductivity(6000 W/MK for SWCNT & MWCNT is 3000
W/MK) that is grater then diamond (2000 W/MK).
Its tensile strength is (45GPa)more then diamond, steel, etc.
Applications:-
 In automobile
Aerospace design
Bio medical sensors
Electronic circuit design
Mechanical reinforcement
Energy storage (hydrogen storage.)

8. Synthesis of CNT:-
There are three methods of synthesis of Carbon Nano Tubes-
•Electric arc-discharge method,
•Laser ablation method and
•Chemical Vapor Deposition (CVD)

9. Electric arc-discharge method

10. Laser ablation method

11. Chemical Vapor Deposition
(CVD)
Reactor tube is made up of Quartz.
CxHx- Carbon precursor
Substrates- SiO2, Al2O3, MgO, TiO2

12. List of different precursors with their phase and
decomposition temperature:-
S No. Precursors Phase Decomposition
Temperature ͦc
1. Methane Gas 500-800
2. Ethane Gas 550-640
3. Acetylene Gas 1500-1800
4. Ethanol Liquid 780-1085
5. Carbon mono
oxide(with
catalyst)
Gas 700
6. Carbon mono
oxide(without
catalyst)
Gas 2900
7. Acetylene(with
catalyst- Fe) used
for MWCNTs
Gas 700

13. Different catalysts used in synthesis of carbon
nano tubes by using chemical vapor deposition (CVD):-
Ni, Fe, Co, Mo, Cu, Au etc.
Catalysts supporters
MgO, Al2O3, SiO2, TiO2. these aare also called substrates
where catalysts are placed in the tube furnace and heated
upto 500 to 1000ºC.

14. Some important points regarding to catalyst
supporters-
• Metal supported on MgO shows low catalytic activity towards
decomposition of methane and this reason impels the researchers to
search the suitable transition metal supported on MgO for effective
production of SWCNTs.
• Ni/Ti02has an advantage over Ni/Si02 by reason of the catalytic
activity of Ni/Ti02 is kept higher during catalyst regeneration cycles.
Conversely, catalytic activity of Ni/Si02 for methane decomposition is
higher at early cycles and decreases gradually with the regeneration
cycles. This phenomenon is mainly due to the changes of these metallic
particles size after several regeneration cycles, i.e. nickel particles in
Ni/Ti02 approach the optimum size for methane decomposition (60-
100nm)-

15. Some important points regarding
to catalyst supporters contd.
-with the regeneration cycles while nickel particles
in Ni/Si02 aggregated into size larger than
150nm, which are inactive for methane
decomposition, after several regeneration cycles.
• Ti02 helps to reduce the activation energy in
methane decomposition, and 60 KJ/mol was
achieved over 13wt% Ni/Ti02 in methane
decomposition reaction. This activation energy is
the lowest activation energy reported in
literature for this reaction.

16. We are working on synthesis of carbon nano
tubes by using chemical vapor deposition based
on Methane.
Methane decomposition temperature for
different catalysts:-
S.No. Catalysts Temperature in
1. Ni/SiO2 500-600
2. Fe/SiO2 680-1200
3. Co/MgO 900-1000
4. Co/Al2O3 475-500
5. Ni/SiO2 700
6. Fe–Co-impregnated
zeolite support
1200

17. CNTs growth mechanism:-
1. Tip growth model
2. Base growth model

18. References
1. Fabrication And Characterization Of Carbon
Nano tubes thesis by Zhiyang Rong
2. Production of carbon nano tubes by chemical
vapor deposition thesis by Umut Baris Ayhan.
3. Synthesis and Electronic Transport in Known
Chirality Single Wall Carbon Nanotubes by
Bhupesh Chandra.
4. A Review on Growth Mechanism and Mass
Production of CNTs by Mukul Kumar and
Yoshinori Ando.