Fabrication of Carbon Nanoribbons from Carbon Nanotube Arrays

Patent metadata

Field	Value
Publication number	US-2017247257-A1
Application number	US-201515510789-A
Country	US
Kind code	A1
Filing date	Sep 14, 2015
Priority date	Sep 12, 2014
Publication date	Aug 31, 2017
Grant date	—

Abstract

Inter-allotropic transformations of carbon are provided using moderate conditions including alternating voltage pulses and modest temperature elevation. By controlling the pulse magnitude, small-diameter single-walled carbon nanotubes are transformed into larger-diameter single-walled carbon nanotubes, multi-walled carbon nanotubes of different morphologies, and multi-layered graphene nanoribbons.

First claim

1 . A method for allotropic transformation of a carbon nanotube material, the method comprising the steps of:
(a) providing a network of the carbon nanotube material, the network spanning a gap between two electrodes and in electrical contact with each of the two electrodes; (b) applying a voltage (V a ) between the electrodes at a temperature above ambient temperature, wherein the voltage is less than the breakdown voltage (V b ) of the network of sp 2 carbon material; (c) cyclically reversing the polarity of V a for a total of “n” voltage cycles, whereby at least a portion of the carbon nanotube material undergoes allotropic transformation.

2 . The method of claim 1 , wherein 1000≦n≦3000.

3 . The method of claim 1 , wherein V a is in the range from 0.4V b to 0.8V b .

4 . The method of claim 1 , wherein the polarity of V a is switched at a frequency of from about 0.1 to about 200 Hz.

5 . The method of claim 1 , wherein the polarity of V a is switched at a frequency of about 100 Hz.

6 . The method of claim 1 , wherein V a is applied as a series of DC pulses, and wherein each pulse is applied for a period of from about 2 msec to about 1000 msec.

7 . The method of claim 6 , wherein each cycle consists of a positive pulse of amplitude V a , a negative pulse of amplitude −V a , and periods between the pulses where V a =0.

8 . The method of claim 6 , wherein the positive and negative pulses last for about 10% of the cycle.

9 . The method of claim 1 , wherein the carbon nanotube material comprises single walled carbon nanotubes (SWCNT), multiwalled carbon nanotubes (MWCNT), or carbon nanotube fiber.

10 . The method of claim 9 , wherein the SWCNT, MWCNT, or carbon nanotube fibers are aligned along an axis extending between the electrodes.

11 . The method of claim 1 , wherein the carbon nanotube material comprises carbon nanotubes at a density of about 18,000-22,000 SWCNT per μm 2 .

12 . The method of claim 1 , wherein the carbon nanotube material comprises SWCNT and the allotropic transformation produces an increase in SWCNT diameter of about 30% to about 40%.

13 . The method of claim 1 , wherein the carbon nanotube material comprises SWCNT and the allotropic transformation produces small bundles of SWCNT having less than 10 SWCNT per bundle.

14 . The method of claim 1 , wherein the carbon nanotube material comprises SWCNT and the allotropic transformation produces large bundles of SWCNT having 10 or more SWCNT per bundle.

15 . The method of claim 1 , wherein V a is about 0.6V b .

16 . The method of claim 15 , wherein the carbon nanotube material comprises SWCNT and the allotropic transformation produces multiwalled carbon nanotubes (MWCNT).

17 . The method of claim 16 , wherein the MWCNT have diameters in the range from about 15 nm to about 30 nm.

18 . The method of claim 16 , wherein some of the MWCNT have incomplete outer wall structure.

19 . The method of claim 16 , wherein the MWCNT have essentially complete outer wall structure.

20 . The method of claim 1 , wherein V a is from about 0.6V b to about 0.8V b .

21 . The method of claim 20 , wherein the allotropic transformation produces multilayered graphene nanoribbons (MGNR).

22 . The method of claim 21 , wherein at least some of the MGNR are in the form of flattened stacks.

23 . The method of claim 21 , wherein at least some of the MGNR are in the form of closed end structures.

24 . The method of claim 21 , wherein at least some of the MGNR are in the form of open end structures.

25 . The method of claim 1 , wherein V a is about 0.8V b .

26 . The method of claim 15 , wherein the allotropic transformation produces multilayered graphitic nanoribbons (MGNR).

27 . The method of claim 1 , wherein the carbon nanotube material comprises SWCNT.

28 . The method of claim 1 , wherein the carbon nanotube material consists of SWCNT.

29 . The method of claim 1 , wherein the carbon nanotube material comprises MWCNT.

30 . The method of claim 1 , wherein the carbon nanotube material consists of MWCNT.

31 . The method of claim 1 , wherein the carbon nanotube material comprises carbon nanotube fibers.

32 . The method of claim 1 , wherein the carbon nanotube material consists of carbon nanotube fibers.

33 . The method of claim 1 , wherein carbon-carbon sp 2 bonds of the carbon nanotube material are rearranged and coalescence-induced modes increase in Raman spectra of the material.

34 . The method of claim 1 , wherein some sp 2 bonds in the carbon nanotube material are converted to sp a bonds.

35 . The method of claim 1 , wherein steps (b) and (c) are performed at a temperature in the range from about 120° C. to about 400° C.

36 . The method of claim 35 , wherein steps (b) and (c) are performed at a temperature of about 180° C.

37 . The method of claim 1 , wherein the method is performed at a temperature below 200° C.

38 . The method of claim 1 , wherein steps (b) and (c) are performed in a vacuum.

39 . The method of claim 1 , wherein the carbon nanotube material and two electrodes are part of a circuit on a chip, and said method is part of a manufacturing process for the chip.

40 . The method of claim 1 , wherein structural defects initially present in the carbon nanotube material are reduced.

41 . The method of claim 1 , wherein the allotropic transformation progresses from forming MWCNT to forming MGNR as the number of voltage cycles increases.

42 . The method of claim 41 , wherein the number of voltage cycles is selected so as to produce a desired allotropic form or mixture of allotropic forms of carbon material.

43 . The method of claim 1 , wherein at least 50% of the initial carbon nanotube material is transformed into a different allotropic form.

44 . The method of claim 1 , wherein at least 90% of the initial carbon nanotube material is transformed into a different allotropic form.

45 . The method of claim 1 , wherein essentially all of the initial carbon nanotube material is transformed into a different allotropic form.

46 . The method of claim 1 , wherein essentially all of the initial carbon nanotube material is transformed into MGNR.

47 . A multilayered graphene nanoribbon (MGNR) carbon material produced by the method of claim 1 .

48 . A circuit comprising the MGNR material of claim 47 .

49 . A composite structural material comprising the MGNR material of claim 47 .

50 . An electronic device comprising a network of multilayered graphene nanoribbons, the network bridging a gap between two electrodes and in electrical contact with each of the two electrodes.

51 . An MGNR material having a thermal conductivity of at least 250 W mK −1 .

Assignees

• Univ Northeastern
• Massachusetts Inst Technology

Inventors

• Jung Yung Joon
• Jung Hyun Young
• Kar Swastik
• Ahn Chi Won
• Dresselhaus Mildred
• Araujo Paulo Antonio Trindade

Classifications

• C01B2204/04

  Specific amount of layers or specific thickness · CPC title

• B01J2219/0803

  employing electric or magnetic energy · CPC title

• Y10S977/932

  for electronic or optoelectronic application · CPC title

• C01B2204/06

  Graphene nanoribbons · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title