Method of producing carbon nanotubes

Abstract

The present teachings are directed to methods of preparing cylindrical carbon structures, specifically single-walled carbon nanotubes, with a desired chirality. The methods include the steps of providing a catalyst component on a substrate and a carbon component, contacting the catalyst component and the carbon component to produce a cylindrical carbon structure. Then, no longer providing the carbon component and determining the chirality of the cylindrical carbon structure. The catalyst component is then cleaned and the process is repeated until the cylindrical carbon structure fulfills a desired characteristic, such as, length. The chirality of the single-walled carbon nanotube grown, after cleaning of the catalyst component, has the same chirality as the initially produced nanotube.

1 . A method of preparing cylindrical carbon structures comprising:
 a) providing a catalyst component on a substrate;   b) providing a carbon component;   c) contacting the catalyst component and the carbon component to produce a first cylindrical carbon structure;   d) stopping providing the carbon component;   e) cleaning the catalyst component;   f) repeating steps b) through e), and   g) producing continued first cylindrical carbon structure having the same chirality as the first cylindrical carbon structure.   
     
     
         2 . The method according to  claim 1 , further comprising:
 determining the chirality of the first cylindrical carbon structure after step d).   
     
     
         3 . The method according to  claim 1 , further comprising:
 repeating step f) until the cylindrical carbon structure satisfies a desired characteristic.   
     
     
         4 . The method according to  claim 3 , wherein the desired characteristic comprises at least one member selected from the group consisting of length, electrical conductivity, thermal conductivity, metallic character, semi-conductor character and non-metallic character. 
     
     
         5 . The method according to  claim 3 , further comprising:
 removing the cylindrical carbon structure from the catalyst component.   
     
     
         6 . The method according to  claim 1 , wherein the catalyst component comprises nanoparticles containing at least one member selected from the group consisting of iron, nickel, cobalt, molybdenum, ruthenium and combinations thereof. 
     
     
         7 . The method according to  claim 1 , wherein the carbon component comprises carbon vapor produced by either a plasma enhanced chemical vapor deposition method or a thermal chemical vapor deposition method. 
     
     
         8 . The method according to  claim 7 , wherein the carbon vapor is produced from a carbon source comprising at least one element selected from the group consisting of methane, ethylene, acetylene and carbon dioxide. 
     
     
         9 . The method according to  claim 1 , wherein cleaning the catalyst component comprises heating the catalyst component to about 750° C. under a reductive atmosphere. 
     
     
         10 . The method according to  claim 9 , wherein cleaning the catalyst component comprises utilizing a method sufficiently active to remove, to the extent that cleaning allows production of the continued cylindrical carbon structure, any coating present on the catalyst component. 
     
     
         11 . The method according to  claim 9 , wherein cleaning the catalyst component comprises utilizing a cleaning method that does not react with the cylindrical carbon structure. 
     
     
         12 - 13 . (canceled) 
     
     
         14 . The method according to  claim 9 , wherein heating comprises exposing the coating to at least one member selected from the group consisting of electromagnetic radiation, laser radiation and microwave radiation. 
     
     
         15 . The method according to  claim 10 , wherein the coating comprises at least one member selected from the group consisting of amorphous carbon, multilayer carbon, metal carbide and combinations thereof. 
     
     
         16 . The method according to  claim 1 , wherein the cylindrical carbon structure comprises at least one member selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes and multi-walled carbon nanotubes. 
     
     
         17 . The method according to  claim 1 , wherein the cylindrical carbon structure comprises single-walled carbon nanotubes. 
     
     
         18 . The method according to  claim 1 , wherein the catalyst component is heated to a temperature ranging from about 600° to about 1000° C. during the contacting step. 
     
     
         19 . (canceled) 
     
     
         20 . A method of preparing single-walled carbon nanotubes comprising:
 a) providing a catalyst component on a substrate;   b) providing a carbon component;   c) contacting the catalyst component and the carbon component to produce a first single-walled carbon nanotube having a chirality;   d) stopping providing the carbon component;   e) cleaning the catalyst component;   f) repeating steps b) through e) to produce a continued first single-walled carbon nanotube with the same chirality as the first single-walled carbon nanotube;   g) repeating step f) until the continued first single-walled carbon nanotube satisfies a desired characteristic; and   h) removing the single-walled carbon nanotube from the catalyst component,   wherein cleaning the catalyst component comprises heating the catalyst component in a reductive atmosphere.   
     
     
         21 . The method according to  claim 20 , further comprising:
 determining the chirality of the first produced single-walled carbon nanotube after step d).   
     
     
         22 . The method according to  claim 20 , wherein the desired characteristic comprises at least one member selected from the group consisting of length, electrical conductivity, thermal conductivity, metallic character, semi-conductor character and non-metallic character. 
     
     
         23 . The method according to  claim 20 , wherein the catalyst component comprises nanoparticles containing at least one member selected from the group consisting of iron, nickel, cobalt, molybdenum, ruthenium and combinations thereof. 
     
     
         24 . The method according to  claim 20 , wherein the carbon component comprises carbon vapor produced by either a plasma enhanced chemical vapor deposition method or a thermal chemical vapor deposition method. 
     
     
         25 . The method according to  claim 24 , wherein the carbon vapor is produced from a carbon source comprising at least one element selected from the group consisting of methane, ethylene, acetylene and carbon dioxide. 
     
     
         26 . The method according to  claim 20 , wherein cleaning the catalyst component comprises heating the catalyst component to about 750° C. 
     
     
         27 . The method according to  claim 26 , wherein cleaning the catalyst component comprises utilizing a method sufficiently active to remove, to the extent that cleaning allows production of the continued single-walled carbon nanotube, any coating present on the catalyst component. 
     
     
         28 . The method according to  claim 26 , wherein cleaning the catalyst component comprises utilizing a cleaning method that does not react with the single-walled carbon nanotube. 
     
     
         29 - 30 . (canceled) 
     
     
         31 . The method according to  claim 26 , wherein heating comprises exposing the coating to at least one member selected from the group consisting of electromagnetic radiation, laser radiation and microwave radiation under a reductive atmosphere. 
     
     
         32 . The method according to  claim 27 , wherein the coating comprises at least one member selected from the group consisting of amorphous carbon, multilayer carbon and metal carbide. 
     
     
         33 . The method according to  claim 20 , wherein the catalyst component is heated to a temperature ranging from about 600° to about 1000° C. during the contacting step.