Metal-carbon nanofiber and production method thereof

Patent metadata

Field	Value
Publication number	US-2018200788-A1
Application number	US-201515744280-A
Country	US
Kind code	A1
Filing date	Jul 28, 2015
Priority date	Jul 28, 2015
Publication date	Jul 19, 2018
Grant date	—

Abstract

The present invention provides a production method of copper-carbon nanofibers, which can realize oxidation-resistant characteristics and process simplification, the production method comprising the steps of: forming a metal precursor-organic nanofiber comprising a metal precursor and an organic substance; and forming a metal-carbon nanofiber by performing a selective oxidation heat treatment to the metal precursor-organic nanofiber so as to simultaneously oxidize carbon of the organic substance and reduce the metal precursor to a metal, wherein the metal has a lower oxidation resistance than the carbon; the selective oxidation heat treatment is performed through a singly heat treatment step, not a plurality of heat treatment steps; and metal-carbon nanofibers with different structures may be formed according to the amount of partial oxygen pressure under which the selective oxidation heat treatment is performed.

First claim

1 . A method for producing a metal-carbon nanofiber, the method comprising the steps of:
forming a metal precursor-organic nanofiber comprising a metal precursor and an organic substance; and forming a metal-carbon nanofiber by performing a selective oxidation heat treatment onto the metal precursor-organic nanofiber such that carbons in the organic substance are oxidized and the metal precursor is reduced into a metal, wherein the metal has a lower oxidation reactivity than carbon; the selective oxidation heat treatment is performed not in a plurality of heat treatment steps but in one heat treatment step; and the metal-carbon nanofibers having structures different from each other are able to be produced according to oxygen partial pressures and/or time for performing the selective oxidation heat treatment.

2 . The method of claim 1 , wherein the metal comprises copper, nickel, cobalt, iron, or silver which is a metal having lower oxidation reactivity than carbon.

3 . The method of claim 1 , wherein the selective oxidation heat treatment is performed in an atmosphere of a first oxygen partial pressure to a second oxygen partial pressure; when the metal precursor-organic nanofiber is heat treated in an atmosphere of an oxygen partial pressure less than the first oxygen partial pressure, metals of the metal precursor are reduced and carbons of the organic substance are also reduced; and
when the metal precursor-organic nanofiber is heat treated in an atmosphere of an oxygen partial pressure higher than the second oxygen partial pressure, metals of the metal precursor are oxidized and carbons of the organic substance are also oxidized.

4 . The method of claim 3 , wherein when the metal precursor-organic nanofiber is heat-treated in an atmosphere of the first oxygen partial pressure to the second oxygen partial pressure, carbons in the metal precursor-organic nanofiber are oxidized and remaining carbons support a structure of the metal precursor-organic nanofiber; and
when the metal precursor-organic nanofiber is heat-treated in an atmosphere of a higher oxygen partial pressure than the second oxygen partial pressure, carbons in the metal precursor-organic nanofiber are oxidized and remaining carbons do not support the structure of the metal precursor-organic nanofiber.

5 . The method of claim 3 , wherein the selective oxidation heat treatment is performed in an atmosphere of an oxygen partial pressure less than a third oxygen partial pressure which is greater than or equal to the first oxygen partial pressure and less than the second oxygen partial pressure; and
when the metal precursor-organic nanofiber is heat treated in an atmosphere of an oxygen partial pressure greater than or equal to the third oxygen partial pressure, a hollow hole is generated inside the metal-carbon nanofiber by diffusion of carbons according to a concentration gradient of residual carbons which remain after carbons in the copper precursor-organic nanofiber are oxidized; and the metal-carbon nanofiber formed by performing the selective oxidation heat treatment in an atmosphere of an oxygen partial pressure which is greater than or equal to the first oxygen partial pressure and less than the third oxygen partial pressure has a structure in which metal particles are uniformly distributed inside a base material and on an outer surface of a fibrous carbon body without a hollow hole.

6 . The method of claim 5 , wherein the selective oxidation heat treatment is performed in an atmosphere of an oxygen partial pressure less than a fourth oxygen partial pressure which is greater than or equal to the third oxygen partial pressure and less than the second oxygen partial pressure; and
when the metal precursor-organic nanofiber is heat treated in an atmosphere of an oxygen partial pressure greater than or equal to the fourth oxygen partial pressure, a hollow hole is generated inside the metal-carbon nanofiber by diffusion of carbons according to a concentration gradient of residual carbons which remain after carbons in the copper precursor-organic nanofiber are oxidized, and metals in the metal-carbon nanofiber are diffused not only to a core but also to an outer surface of the metal-carbon nanofiber; and the metal-carbon nanofiber formed by performing the selective oxidation heat treatment in an atmosphere of an oxygen partial pressure, which is greater than or equal to the third oxygen partial pressure and less than the fourth oxygen partial pressure, has a core-shell structure in which metal particles form the core and carbons form a shell surrounding the core.

7 . The method of claim 6 , wherein the selective oxidation heat treatment is performed in an atmosphere of an oxygen partial pressure less than a fifth oxygen partial pressure which is greater than or equal to the fourth oxygen partial pressure and less than the second oxygen partial pressure; and
when the metal precursor-organic nanofiber is heat treated in an atmosphere of an oxygen partial pressure greater than or equal to the fifth oxygen partial pressure, a hollow hole is generated inside the metal-carbon nanofiber by diffusion of carbons according to a concentration gradient of residual carbons which remain after carbons in the copper precursor-organic nanofiber are oxidized, and a portion of an outer surface of the metal-carbon nanofiber is thinned and ruptured; and the metal-carbon nanofiber formed by performing the selective oxidation heat treatment in an atmosphere of an oxygen partial pressure, which is greater than or equal to the fourth oxygen partial pressure and less than the fifth oxygen partial pressure, has a structure in which metal particles are distributed inside a base material and an outer surface of a tubular carbon body defining the hollow hole, and inside the hollow hole.

8 . The method of claim 7 , wherein the selective oxidation heat treatment is performed in an atmosphere of an oxygen partial pressure which is greater than or equal to the fifth oxygen partial pressure and less than the second oxygen partial pressure; and
the metal-carbon nanofiber formed by performing the selective oxidation heat treatment on the metal precursor-organic nanofiber in an atmosphere of an oxygen partial pressure, which is greater than or equal to the fifth oxygen partial pressure and less than the second oxygen partial pressure, has a structure in which carbons in the metal precursor-organic nanofiber is oxidized, a hollow hole is formed by a concentration gradient of remaining carbons, a portion of an outer surface of the metal-carbon nanofiber is thinned and ruptured, and metals are distributed in an outer surface of a carbon body and in the hollow hole.

9 . The method of claim 1 , wherein according to a time period for performing the selective oxidation heat treatment:
a structure in which metal particles are uniformly distributed inside the base material and the outer surface of a fibrous carbon body without a hollow hole; a core-shell structure in which metals form a core and carbons form a shell surrounding the metals; a structure in which metal particles are distributed inside a base material and on the surface of the tubular carbon body defining a hollow hole, and inside the hollow hole; and a structure, in which a hollow hole is formed inside a nanofiber, a portion of the outer surface of the metal-carbon nanofiber is thinned and ruptured, and metals are distributed on the outer surface of a carbon body and inside the hollow hole, are sequentially formed.

10 . The method of claim 9 , wherein while the selective oxidation heat treatment is performed, the oxygen partial pressure is constant.

11 . The method of claim 1 , wherein the metal prec

Assignees

• Seoul Nat Univ R&Db Foundation

Inventors

• Joo Young Chang
• Nam Dae Hyun

Classifications

• B22F1/142

  Thermal or thermo-mechanical treatment · CPC title

• B22F1/0547

  Nanofibres or nanotubes · CPC title

• B22F1/16

  Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10) · CPC title

• D01D1/02 Primary

  Preparation of spinning solutions · CPC title

• D01F11/00

  Chemical after-treatment of artificial filaments or the like during manufacture · CPC title