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Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
Synthesis of CNTs
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Synthesis of CNTs

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Transcript

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

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