Synthesis of CNTs

1,228 views
1,130 views

Published on

0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
1,228
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
0
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Synthesis of CNTs

  1. 1. Carbon Nanotubes<br />Introduction<br /> & <br />Synthesis<br />
  2. 2. Introduction: Common Facts<br /><ul><li> Discovered in 1991 by Iijima
  3. 3. Unique material properties
  4. 4. Nearly one-dimensional structures
  5. 5. Single - and Multi-walled</li></li></ul><li>Introduction: nanotube structure<br />Roll a graphene sheet in a certain direction:<br /><ul><li>Armchair structure
  6. 6. Zigzag structure
  7. 7. Chiral structure</li></ul>Defects result in bends and transitions<br />
  8. 8. Introduction: special properties<br /><ul><li> Difference in chemical reactivity for end caps and side wall
  9. 9. High axial mechanical strength
  10. 10. Special electrical properties: </li></ul>Metallic<br /> Semi conducting<br />
  11. 11. Synthesis: growth mechanism<br />Metal Catalyst<br />Tip Growth / Extrusion Growth<br />
  12. 12. Synthesis: overview<br />Commonly Applied Techniques:<br /><ul><li> Chemical Vapor Deposition (CVD)
  13. 13. Arc-Discharge
  14. 14. Laser ablation</li></ul>Techniques Differ in:<br /><ul><li> Type of nanotubes (SWNT / MWNT / Aligned)
  15. 15. Catalyst used
  16. 16. Yield
  17. 17. Purity</li></li></ul><li>Synthesis: CVD<br /><ul><li> Gas phase deposition
  18. 18. Large scale possible
  19. 19. Relatively cheap
  20. 20. SWNTs / MWNTs
  21. 21. Aligned nanotubes
  22. 22. Patterned substrates</li></li></ul><li>Synthesis: laser ablation<br /><ul><li> Catalyst / no catalyst
  23. 23. MWNTs / SWNTs
  24. 24. Yield <70%
  25. 25. Use of very strong laser
  26. 26. Expensive (energy costs)
  27. 27. Commonly applied</li></li></ul><li>Synthesis: arc discharge<br /><ul><li>Relatively cheap
  28. 28. Many side-products
  29. 29. MWNTs and SWNTs
  30. 30. Batch process</li></li></ul><li>Purification<br />Contaminants:<br /><ul><li> Catalyst particles
  31. 31. Carbon clusters
  32. 32. Smaller fullerenes: C60 / C70</li></ul>Impossibilities:<br /><ul><li> Completely retain nanotube structure
  33. 33. Single-step purification </li></ul>Only possible on very small scale:<br /><ul><li> Isolation of either semi-conducting SWNTs</li></li></ul><li>Purification: techniques<br />Removal of catalyst:<br /><ul><li> Acidic treatment (+ sonication)
  34. 34. Thermal oxidation
  35. 35. Magnetic separation (Fe)</li></ul>Removal of small fullerenes<br /><ul><li>Micro filtration
  36. 36. Extraction with CS2</li></ul>Removal of other carbonaceous impurities<br /><ul><li> Thermal oxidation
  37. 37. Selective functionalization of nanotubes
  38. 38. Annealing</li>

×