Carbon nanotube substrates and catalyzed hot stamp for polishing and patterning the substrates

• US 20080105648A1
• Filed: 12/14/2005
• Published: 05/08/2008
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: Rice University
• Original Assignee: Rice University
• Inventors: Kittrell, W. Carter, Schmidt, Howard K., Wang, Yuhuang, Kim, Myung Jong, Hauge, Robert H.
• Granted Patent: US 7,585,420 B2
• Time in Patent Office: Days
• US Class Current: 216/13
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2202/02 Single-walled nanotubes
• CPC Class Codes: C01B 32/168 After-treatment
• CPC Class Codes: Y10S 977/745 having a modified surface

Abstract

The present invention is generally directed to catalyzed hot stamp methods for polishing and/or patterning carbon nanotube-containing substrates. In some embodiments, the substrate, as a carbon nanotube fiber end, is brought into contact with a hot stamp (typically at 200-800° C.), and is kept in contact with the hot stamp until the morphology/patterns on the hot stamp have been transferred to the substrate. In some embodiments, the hot stamp is made of material comprising one or more transition metals (Fe, Ni, Co, Pt, Ag, Au, etc.), which can catalyze the etching reaction of carbon with H₂, CO₂, H₂O, and/or O₂. Such methods can (1) polish the carbon nanotube-containing substrate with a microscopically smooth finish, and/or (2) transfer pre-defined patterns from the hot stamp to the substrate. Such polished or patterned carbon nanotube substrates can find application as carbon nanotube electrodes, field emitters, and field emitter arrays for displays and electron sources.

Claims

1. A method comprising the steps of:

a) contacting a carbon nanotube (CNT) fiber with a metal surface to form a CNT-metal interface, wherein the CNT fiber contacts the metal surface at an end of the CNT fiber; and

b) heating the CNT-metal interface in an etching atmosphere at a temperature that permits catalytic etching of the end of the CNT fiber to provide an end-etched CNT fiber.

2. The method of claim 1, wherein the CNT fiber comprises single-wall carbon nanotubes.

3. The method of claim 1, wherein the metal surface comprises transition metal.

4. The method of claim 1, wherein the metal surface comprises metal selected from the group consisting of Fe, Ni, Co, Pt, Ag, Au, and combinations thereof.

5. The method of claim 1, wherein the etching atmosphere comprises a gas selected from the group consisting of H₂, CO₂, O₂, H₂O, and combinations thereof.

6. The method of claim 1, wherein the end of the end-etched CNT fiber is polished.

7. The method of claim 1, wherein the end of the end-etched CNT fiber is patterned.

8. The method of claim 1, wherein the end of the end-etched CNT fiber has a microscopically smooth finish.

9. The method of claim 1, wherein the end-etched CNT fiber is utilized in an application selected from the group consisting of electrodes, field emitters and arrays thereof, electron sources, displays, and combinations thereof.

10. The method of claim 1, further comprising feeding the end of the CNT fiber into the metal surface as the end of the CNT fiber is etched.

11. The method of claim 10, wherein the step of feeding utilizes a means of feeding the end of the CNT fiber into the metal surface.

12. The method of claim 10, wherein the step of feeding utilizes a piezoelectric device to which the CNT fiber is mounted.

13. The method of claim 12, further comprising establishing an open electric circuit using the CNT fiber as a first electrode of the open electric circuit and the metal surface as a second electrode of the open electric circuit, wherein a potential is applied to the open electric circuit.

14. The method of claim 13, wherein the CNT fiber is brought into contact with the metal surface to establish a closed electric circuit through which current flows.

15. The method of claim 14, wherein the current flowing through the closed electric circuit increases as the CNT fiber is directed into the metal surface while simultaneously being etched, the etching producing a microscopically flat fiber end when the current flowing through the circuit stabilizes at a maximum value.

16. The method of claim 1, further comprising cleaning the end-etched CNT fiber in an acidic solution.

17. The method of claim 1, further comprising heating the end-etched CNT fiber in H₂ to remove any surface oxides on the end of the end-etched CNT fiber.

18. A method comprising the steps of:

a) contacting a single-wall carbon nanotube (SWNT) fiber with a transition metal surface to form a SWNT-metal interface, wherein the SWNT fiber contacts the metal surface at an end of the SWNT fiber; and

b) heating the SWNT-metal interface in an etching atmosphere at a temperature that is operable for catalytic etching of the end of the SWNT fiber to provide an end-etched SWNT fiber.

19. The method of claim 18, wherein the etching atmosphere comprises a gas selected from the group consisting of H₂, CO₂, O₂, and combinations thereof.

20. The method of claim 18, wherein the end of the end-etched SWNT fiber is polished.

21. The method of claim 18, wherein the end of the end-etched SWNT fiber end is patterned.

22. The method of claim 18, further comprising feeding the end of the SWNT fiber into the metal surface as the end of the SWNT fiber is etched.

23. The method of claim 22, wherein the step of feeding utilizes a means of feeding the end of the SWNT fiber into the metal surface.

24. A method comprising the steps of:

a) contacting a small-diameter carbon nanotube (SDCNT) fiber with a transition metal surface to form a SDCNT-metal interface, wherein the SDCNT fiber contacts the metal surface at an end of the SDCNT fiber; and

b) heating the SDCNT-metal interface in an etching atmosphere at a temperature that is operable for catalytic etching of the end of the SDCNT fiber to provide an end-etched SDCNT fiber.

25. The method of claim 24, wherein the etching atmosphere comprises a gas selected from the group consisting of H₂, CO₂, O₂, H₂O, and combinations thereof.

26. The method of claim 24, wherein the end of the end-etched SDCNT fiber is polished.

27. The method of claim 24, wherein the end of the end-etched SDCNT fiber end is patterned.