# US 9,751,765 B2 · Methods to superheat carbon nanotubes

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- Number: US 9,751,765 B2
- Document ID: US9751765B2
- Status: Granted
- Kind: B2
- Application number: 15/044,766
- Filed: 2016-02-16
- Published: 2016-08-18
- Granted: 2017-09-05
- Earliest claimed: 2015-02-13
- Assignees: University of Cincinnati
- Applicants: University of Cincinnati
- Inventors: Aaron Johnson; David Mast
- Web page: https://patentgrep.com/patent/US9751765B2

## CPC

- C01B 32/168: After-treatment
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

A method for annealing multi-walled carbon nanotubes includes applying a high-frequency electromagnetic field to the carbon nanotubes and causing the carbon nanotubes to self-heat to a temperature and for a time effective to reduce defects and reduce a number of walls in some of the carbon nanotubes.

## Claims

### Claim 1

A method for annealing multi-walled carbon nanotubes comprising:
applying a high-frequency electromagnetic field to the carbon nanotubes; and
causing the carbon nanotubes to self-heat to a temperature and for a time effective to reduce defects and reduce a number of walls in some of the carbon nanotubes,
wherein causing the carbon nanotubes to self-heat includes reducing the number of walls in some of the carbon nanotubes through sublimation.

### Claim 2 (depends on 1)

The method of claim 1, wherein applying the high-frequency electromagnetic field includes generating electromagnetic waves having a wavelength of about 1 MHz to about 100 GHz.

### Claim 3 (depends on 2)

The method of claim 2, wherein applying the high-frequency electromagnetic field includes generating microwaves.

### Claim 4 (depends on 2)

The method of claim 2, wherein applying the high-frequency electromagnetic field includes generating radio waves.

### Claim 5 (depends on 1)

The method of claim 1, wherein applying the high-frequency electromagnetic field includes applying the high-frequency electromagnetic field in an inert environment.

### Claim 6 (depends on 1)

The method of claim 1, wherein applying the high-frequency electromagnetic field includes applying the high-frequency electromagnetic field for a time of less than about one minute.

### Claim 7 (depends on 1)

The method of claim 1, wherein applying the high-frequency electromagnetic field includes applying the high-frequency electromagnetic field for a time of at least about thirty seconds.

### Claim 8 (depends on 1)

The method of claim 1, wherein applying the high-frequency electromagnetic field includes using at least one of a waveguide, a reflecting lens dish, and a capacitor applicator.

### Claim 9 (depends on 1)

The method of claim 1, wherein causing the carbon nanotubes to self-heat includes causing the carbon nanotubes to self-heat to a temperature of about 2800° C. to about 5000° C.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
conveying the carbon nanotubes through the high-frequency electromagnetic field.

### Claim 11 (depends on 1)

The method of claim 1, further comprising:
processing the carbon nanotubes before applying the high-frequency electromagnetic field.

### Claim 12 (depends on 11)

The method of claim 11, wherein processing the carbon nanotubes includes preheating the carbon nanotubes.

### Claim 13 (depends on 12)

The method of claim 12, wherein preheating the carbon nanotubes includes preheating the carbon nanotubes to a temperature of less than about 500° C. in an oxidative environment.

### Claim 14 (depends on 11)

The method of claim 11, wherein processing the carbon nanotubes includes processing the carbon nanotubes in an inert environment or an acidic environment.

### Claim 15 (depends on 11)

The method of claim 11, wherein processing the carbon nanotubes includes processing the carbon nanotubes in a vacuum.

### Claim 16

A method for annealing multi-walled carbon nanotubes comprising:
applying a high-frequency electromagnetic field to the carbon nanotubes for a time of less than about one minute; and
causing the carbon nanotubes to self-heat to a temperature and for a time effective to reduce defects and reduce a number of walls in some of the carbon nanotubes.

### Claim 17 (depends on 16)

The method of claim 16, wherein causing the carbon nanotubes to self-heat includes causing the carbon nanotubes to self-heat to a temperature of about 2800° C. to about 5000° C.

### Claim 18

A method for annealing multi-walled carbon nanotubes comprising:
applying a high-frequency electromagnetic field to the carbon nanotubes; and
causing the carbon nanotubes to self-heat to a temperature of about 2800° C. to about 5000° C. and for a time effective to reduce defects and reduce a number of walls in some of the carbon nanotubes.

### Claim 19 (depends on 18)

The method of claim 18, wherein applying the high-frequency electromagnetic field includes applying the high-frequency electromagnetic field for a time of less than about one minute, and
wherein causing the carbon nanotubes to self-heat includes reducing the number of walls in some of the carbon nanotubes through sublimation.