Methods of preparing and purifying carbon nanotubes, carbon nanotubes, and an element using the same

Abstract

A method of preparing carbon nanotubes (CNT), a method of purifying carbon nanotubes, carbon nanotubes, and an element using said carbon nanotubes are provided. The method includes preparing carbon nanotubes by arc-discharge and employs a coordination chemistry process to remove a catalyst and/or optional promoter used in arc-discharge.

1 . A method for preparing carbon nanotubes, the method comprising:
 producing carbon nanotubes by an arc-discharge method in presence of a catalyst and optionally a promoter;   coordinating the metal elements present in the catalyst and/or the optional promoter with a substance capable of forming a complex with the metal elements to produce a complex; and   removing the complex.   
     
     
         2 . The method of  claim 1 , wherein the promoter is employed. 
     
     
         3 . The method of  claim 2 , wherein the promoter is FeS. 
     
     
         4 . The method of  claim 1 , wherein the catalyst is selected from the group consisting of lanthanum metal oxide, transition metal, the mixture of nickel and a rare earth element, and mixtures thereof. 
     
     
         5 . The method of  claim 1 , wherein the catalyst is selected from the group consisting of Y—Ni alloy, Fe—Ni alloy, Fe—Co alloy, Co—Ni alloy, Rh—Pt alloy, and Ce—Ni alloy. 
     
     
         6 . The method of  claim 1 , wherein coordinating the metal elements includes:
 converting the metal elements present in the catalyst and/or the optional promoter into ions; and   coordinating the ions with the substance capable of forming a complex with the metal elements present in the catalyst and/or the optional promoter to produce a complex.   
     
     
         7 . The method of  claim 6 , wherein converting the metal elements includes:
 oxidizing the catalyst and/or the optional promoter to produce the oxides thereof.   
     
     
         8 . The method of  claim 7 , wherein corresponding metal ions are obtained from the oxide by using the substance capable of forming a complex with the metal elements present in the catalyst and/or optionally the promoter, and are coordinated with the substance to produce a complex. 
     
     
         9 . The method of  claim 8 , wherein the substance capable of forming a complex with the metal elements present in the catalyst and/or optionally promoter is selected from aminopolycarboxylic acids. 
     
     
         10 . The method of  claim 9 , wherein the aminopolycarboxylic acid is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), trans-1,2-diaminocyclohe-xane-N,N,N′,N′-tetracetic acid hydrate (CYDTA), diethylenetriaminepentaacetic acid (DTPA), and triethylenetetraaminehexaacetic acid (TTHA). 
     
     
         11 . The method of  claim 9 , wherein the aminopolycarboxylic acid is triethylenetetraaminehexaacetic acid (TTHA). 
     
     
         12 . The method of  claim 1 , wherein removing the complex includes converting the complex into a salt form and removing the complex in the salt form. 
     
     
         13 . The method of  claim 7 , wherein converting the metal elements further comprises:
 reacting the oxides with an acid to produce ions of the metal elements present in the catalyst and/or the optional promoter.   
     
     
         14 . The method of  claim 6 , wherein the substance capable of forming a complex with the metal elements present in the catalyst and/or optionally the promoter is selected from the group consisting of tetrahydrofuran, trialkyl phosphine, ε-caprolactone, ε-caprolactam, dimethyl formamide, and dimethyl sulfoxide. 
     
     
         15 . The method of  claim 6 , wherein the complex is selected from the group consisting of {M[(NC) 2 CC(OCH 2 CH 2 OH)C(CN) 2 ] 2 (4,4′-bpy)(H 2 O) 2 }, Dinuclear [{M′(phen) 2 } 2 V 4 O 12 ]C 6 H 12 O.H 2 O and [Ni(L)(H 2 O) 3 ]2H 2 O, wherein M is selected from Ni, Fe and Co; M′ is selected from Ni and Co; bpy is bipyridine; phen is phenyl; L is (2-methoxycarbonylmethylimino-5-methyl-thiazol-3-yl)-acetic acid. 
     
     
         16 . The method of  claim 7 , wherein oxidizing the catalyst comprises oxidizing the catalyst and/or optionally the promoter with an oxygen containing gas. 
     
     
         17 . The method of  claim 16 , wherein the oxidation time and the oxidation temperature of the oxygen containing gas are sufficient to convert the catalyst and/or the optional promoter into oxides. 
     
     
         18 . The method of  claim 16 , wherein the oxygen containing gas is air. 
     
     
         19 . The method of  claim 17 , wherein the oxidation temperature is about 80° C. to about 300° C. 
     
     
         20 . The method of  claim 17 , wherein the oxidation time is about 1 hour to about 20 hours. 
     
     
         21 . The method of  claim 1 , further comprising centrifugation after removing the complex. 
     
     
         22 . The method of  claim 21 , wherein centrifugation is carried out at a speed of about 5000 rpm to about 30000 rpm for about 1 hour to about 20 hours. 
     
     
         23 . The method according to  claim 1 , wherein the carbon nanotubes are single-walled carbon nanotubes. 
     
     
         24 . A method for purifying carbon nanotubes produced by an arc-discharge method in the presence of a catalyst and optionally a promoter, the method comprising:
 coordinating the metal elements present in the catalyst and/or the optional promoter with a substance capable of forming a complex with the metal elements to produce a complex; and   removing the complex.   
     
     
         25 . The method of  claim 24 , wherein coordinating the metal elements includes:
 converting the metal elements present in the catalyst and/or the optional promoter into ions; and   coordinating the ions with the substance capable of forming a complex with the metal elements present in the catalyst and/or the optional promoter to produce a complex.   
     
     
         26 . The method of  claim 25 , wherein converting the metal elements includes: oxidizing the catalyst and/or the optional promoter to produce the oxides thereof. 
     
     
         27 . The method of  claim 26 , wherein corresponding metal ions are obtained from the oxide by using the substance capable of forming a complex with the metal elements present in the catalyst and/or the optional promoter, and are coordinated with the substance to produce a complex. 
     
     
         28 . The method of  claim 27 , wherein the substance capable of forming a complex with the metal elements present in the catalyst and/or the optional promoter is selected from aminopolycarboxylic acids. 
     
     
         29 . The method of  claim 28 , wherein said aminopolycarboxylic acid is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), trans-1,2-diaminocyclohe-xane-N,N,N′,N′-tetracetic acid hydrate (CYDTA), diethylenetriaminepentaacetic acid (DTPA) and triethylenetetraaminehexaacetic acid (TTHA). 
     
     
         30 . The method of  claim 28 , wherein the aminopolycarboxylic acid is triethylenetetraaminehexaacetic acid (TTHA). 
     
     
         31 . The method of  claim 24 , wherein removing the complex comprises converting the complex into a salt form and removing the complex in the salt form. 
     
     
         32 . The method of  claim 26 , wherein oxidizing the catalyst and/or optional promoter comprises:
 reacting the oxides with an acid to produce ions of the metal elements present in the catalyst and/or the optional promoter.   
     
     
         33 . The method of  claim 24 , wherein said catalyst is selected from Y—Ni alloy, Fe—Ni alloy, Fe—Co alloy, Co—Ni alloy, Rh—Pt alloy, and Ce—Ni alloy. 
     
     
         34 . The method of  claim 25 , wherein the substance capable of forming a complex with the metal elements present in the catalyst and/or the optional promoter is selected from the group consisting of tetrahydrofuran, trialkyl phosphine, ε-caprolactone, ε-caprolactam, dimethyl formamide, and dimethyl sulfoxide. 
     
     
         35 . The method of  claim 25 , wherein the complex is selected from M[(NC) 2 CC(OCH 2 CH 2 OH)C(CN) 2 ] 2 (4,4′-bpy)(H 2 O) 2 }, Dinuclear [{M′(phen) 2 } 2 V 4 O 12 ]C 6 H 12 O.H 2 O and [Ni(L)(H 2 O) 3 ]2H 2 O, wherein M is selected from Ni, Fe and Co; M′ is selected from Ni and Co; bpy is bipyridine; phen is phenyl; L is (2-methoxycarbonylmethylimino-5-methyl-thiazol-3-yl)-acetic acid. 
     
     
         36 . The method of  claim 26 , wherein the catalyst and/or the optional promoter are oxidized with an oxygen containing gas. 
     
     
         37 . The method of  claim 36 , wherein an oxidation time and an oxidation temperature of the oxygen containing gas are sufficient to convert the catalyst and/or the optional promoter into oxides. 
     
     
         38 . The method of  claim 36 , wherein the oxygen containing gas is air. 
     
     
         39 . The method of  claim 37 , wherein the oxidation temperature is about 80° C. to about 300° C. 
     
     
         40 . The method of  claim 37 , wherein the oxidation time is about 1 hour to about 20 hours. 
     
     
         41 . The method of  claim 24 , further comprising a centrifugation step after removing the complex. 
     
     
         42 . The method of  claim 41 , wherein the centrifugation step is carried out at a speed of about 5000 rpm to about 30000 rpm for about 1 hour to about 20 hours. 
     
     
         43 . The method according to  claim 24 , wherein the carbon nanotubes are single-walled carbon nanotubes. 
     
     
         44 . A carbon nanotube material comprising carbon nanotubes produced by arc-discharge in presence of a catalyst and optionally a promoter, wherein metal elements present in the catalyst and/or the optional promoter are coordinated with a substance capable of forming a complex with the metal elements to produce a complex, and wherein the complex is removed. 
     
     
         45 . An element of carbon nanotubes comprising a carbon nanotube material including carbon nanotubes produced by arc-discharge in presence of a catalyst and optionally a promoter, wherein metal elements present in the catalyst and/or the optional promoter are coordinated with a substance capable of forming a complex with the metal elements to produce a complex, and wherein the complex is removed. 
     
     
         46 . The element of carbon nanotubes of  claim 45 , wherein the element of carbon nanotubes is selected from the group consisting of conductive film of carbon nanotubes, field emission source, transistor, conductive wire, nano-electro-mechanic system, spin conduction device, nano cantilever, quantum computing device, lighting emitting diode, solar cell, surface-conduction electron-emitter display, filter, drug delivery system, thermal conductive material, nano nozzle, energy storage system, space elevator, fuel cell, sensor, and catalyst support material.