1. The wondrous world of carbon nanotubes Final Presentation IFP 2 February 26, 2003

2. Group members: Client: Prof. P.H.L. Notten (Philips / TU/e) ir. R.A.H. Niessen (Philips) Tutor: X.E.E. Reynhout IFP group 2 M.Daenen (N) P.G.A.Janssen (ST) R. de Fouw (ST) K. Schouteden (N) B. Hamers (ST) M.A.J. Veld (ST)

3. Overview Introduction Synthesis & Purification Overview of applications Single nanotube measurements Energy storage Molecular electronics Conclusion and future outlook

4. Introduction: common facts Discovered in 1991 by Iijima Unique material properties Nearly one-dimensional structures Single- and multi-walled

5. Introduction: nanotube structure Roll a graphene sheet in a certain direction: Armchair structure Zigzag structure Chiral structure Defects result in bends and transitions

6. Introduction: special properties Difference in chemical reactivity for end caps and side wall High axial mechanical strength Special electrical properties: –Metallic –Semi conducting

7. Synthesis: growth mechanism Metal catalyst Tip growth / extrusion growth

8. Synthesis: overview Commonly applied techniques: –Chemical Vapor Deposition (CVD) –Arc-Discharge –Laser ablation Techniques differ in: –Type of nanotubes (SWNT / MWNT / Aligned) –Catalyst used –Yield –Purity

9. Synthesis: CVD Gas phase deposition Large scale possible Relatively cheap SWNTs / MWNTs Aligned nanotubes Patterned substrates

10. Synthesis: arc discharge MWNTs and SWNTs Batch process Relatively cheap Many side-products

11. Synthesis: laser ablation Catalyst / no catalyst MWNTs / SWNTs Yield <70% Use of very strong laser Expensive (energy costs) Commonly applied

12. Purification Contaminants: – Catalyst particles – Carbon clusters – Smaller fullerenes: C 60 / C 70 Impossibilities: –Completely retain nanotube structure –Single-step purification Only possible on very small scale: –Isolation of either semi-conducting SWNTs

13. Purification: techniques Removal of catalyst: –Acidic treatment (+ sonication) –Thermal oxidation –Magnetic separation (Fe) Removal of small fullerenes – Micro filtration – Extraction with CS 2 Removal of other carbonaceous impurities –Thermal oxidation –Selective functionalisation of nanotubes –Annealing

14. Overview of potential applications < Energy storage: Li-intercalation Hydrogen storage Supercaps > FED devices: Displays < AFM Tip > Molecular electronics Transistor < Others Composites Biomedical Catalyst support Conductive materials ???

15. Overview of potential applications < Energy storage: Li-intercalation Hydrogen storage Supercaps > FED devices: Displays < AFM Tip > Molecular electronics Transistor < Others Composites Biomedical Catalyst support Conductive materials ???

16. Overview of potential applications < Energy storage: Li-intercalation Hydrogen storage Supercaps > FED devices: Displays < AFM Tip > Molecular electronics Transistor < Others Composites Biomedical Catalyst support Conductive materials ???

17. Energy Storage Experiments & Modelling Electrochemical Storage of Lithium Electrochemical Storage of Hydrogen Gas Phase Intercalation of Hydrogen Supercapacitors

18. Energy Storage 3-electrode cell Work Electrode Counter Electrode

19. Lithium Electrochemical Model

20. Equilibrium saturation composition for graphite: LiC 6 Purified SWNT bundles: Li 1.7 C 6 Ball-milled SWNTs: Li 2.7 C 6 20 min 10 min 0 min Lithium Electro Chemical

21. Etching Two types: lengths of 4 and 0.5 μm Good C rev (Li 2.1 C 6 ) Smaller hysteresis Cut SWNTs have better properties concerning Li intercalation Voltage [V]

22. Hydrogen Electrochemical Lennard Jones Potential

23. Hydrogen Electrochemical storage model Model of Hydrogen Storage at room temperature for different diameters of SWNTs

24. Hydrogen Electrochemical Charging & Discharging Charge  Discharge Cycle

25. Hydrogen Electrochemical Many contrasting conclusions: –Positive Ranging from: 0.4 – 2.3 wt% H –Negative: No systematic relationship between purity and storage  storage not due to SWNTs More investigations on the mechanism of storage are needed in order to explain this wide range of results

26. Gas Phase Intercalation of Hydrogen model

27. Gas Phase Intercalation of Hydrogen Contrast in results is very high: range from 0-67 wt% Reasonable range: 2-10 wt% More modelling needed To compare models they have to use the same parameters

28. Super Capacitor Electrochemical double layer

29. Molecular electronics FEDs CNTFETs SETs

30. Field Emitting Devices Single Emitter Film Emitter

31. Field Emitting Devices Single Emitter Film Emitter

32. Field Emitting Devices Single Emitter Film Emitter

33. Patterned Film Field Emitters Etching and lithography Conventional CVD Soft lithography

34. Transistor Principle in CNTFETs  Transistor CNTFET 

35. Doping of CNTs

36. Single Electron transistor

37. Conclusions Mass production is nowadays too expensive Many different techniques can be applied for investigation Large scale purification is possible FEDs and CNTFETs have proven to work and are understood Positioning of molecular electronics is difficult Energy storage is still doubtful, fundamental investigations are needed