US20080292530A1 - Calcination of carbon nanotube compositions - Google Patents

Abstract

A carbon nanotube composition and method of making the same. The composition is made by: heating a precursor composition under a non-oxidizing or reducing atmosphere to form a carbon composition of carbon nanotubes and amorphous carbon; and calcining the carbon composition in the presence of oxygen to oxidize and vaporize the amorphous carbon without oxidizing the carbon nanotubes. The precursor composition includes a mixture or complex of a transition metal compound and an organic compound that chars at elevated temperatures.

Description

• This application claims the benefit of U.S. Provisional Patent Application No. 60/917,347, filed on May 11, 2007. This application and all other referenced publications and patent documents throughout this application are incorporated herein by reference.
FIELD OF THE INVENTION
• The invention is generally related to carbon nanotube compositions.
DESCRIPTION OF RELATED ART
• Since the discovery of carbon nanotubes, many studies have been carried out in an effort to increase the production yield, to reduce the cost, to remove amorphous carbon, and to improve the quality of carbon nanotubes. Small quantities of carbon nanotubes can now be produced daily by methods such as arc discharge, laser vaporization, and chemical vapor decomposition (CVD). These methods yield carbon nanotubes embedded in powdered soot. The synthesis of cost-effective, good quality carbon nanotubes in high yields remains a challenge in these systems. Experimental tests and applications of such carbon structures have been hampered by the difficulty in obtaining pure, homogenous, and uniform samples of highly graphitic nanotubes. The impurities in the soot are amorphous carbon and high concentrations of metal nanoparticles. Some of the amorphous carbon can be removed from the soot by calcination to enhance the purity of the nanotubes. Multiple washing with acid solutions removes some of the metal impurities but at least 5-10% by weight of metal remains in all samples. The washings can also damage the nanotubes. The purer carbon nanotubes produced by the CVD method are available as a powder but do not, exhibit structural integrity.
SUMMARY OF THE INVENTION
• Disclosed herein is a carbon nanotube composition and method of making the same. The composition is made by: heating a precursor composition under a non-oxidizing or reducing atmosphere and under thermal conditions effective to form a carbon composition comprising carbon nanotubes and amorphous carbon; and calcining the carbon composition in the presence of oxygen under thermal conditions that oxidize and vaporize the amorphous carbon without oxidizing the carbon nanotubes. The precursor composition comprises a mixture or complex of: a transition metal compound; and an organic compound that chars at elevated temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
• A more complete appreciation of the invention will be readily obtained by reference to the following Description of the Example Embodiments and the accompanying drawings.
• FIG. 1 shows the synthetic scheme for synthesis of carbon nanotubes in bulk solid.
• FIG. 2 shows scanning electron micrographs (SEM) of the surface of a pyrolyzed, Ni-catalyzed multi-walled nanotube (MWNT) solid (a) before, and (b) after calcination at 480° C.
• FIG. 3 shows X-ray diffraction studies confirming the removal of amorphous carbon in a calcined CNT sample. The top graph (as pyrolyzed to 1000° C.) shows intensity due to the amorphous carbon content between 20 and 25 degrees on the 2-theta axis.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
• In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and devices are omitted so as to not obscure the description of the present invention with unnecessary detail.
• The disclosed method pertains to a general and broad method for the purification of carbon nanotubes, formed in a solid carbonaceous solid, using selective combustion techniques under oxidizing conditions (i.e., calcination). Calcination at selected temperatures permits the removal of the amorphous carbon from the carbonaceous solid, while preserving the carbon nanotube content. During the formation and production of carbon nanotubes by heat treatment of a precursor composition such as an organometallic compound or a carbon source and varying amount of a metal salt or organometallic compound, carbon nanotubes and some amorphous carbon are formed in the carbonaceous solid. The amount of carbon nanotubes and amorphous carbon in the carbonaceous solid will depend on the temperature and the time of exposure. By this method, the amorphous carbon is removed oxidatively by heating the carbonaceous solid in a flow of air or O₂at various temperatures up to about 500° C. leaving the crystalline nanotubes intact in the shaped solid. Within the carbonaceous solid, metal nanoparticles can be present in catalytic or in larger quantities depending on the amount of reactants used in the preparation. The metal nanoparticles may be oxidized during the calcination.
• Any organic compound that chars can be used as a precursor for the formation of carbon nanotube-metal nanoparticle compositions in a shaped carbonaceous solid during the carbonization process. Resins such as polyimides, epoxies, phthalonitriles, cyanate ester resins, polyacrylonitrile, phenolic resins, petroleum and coal pitches, polyaromaticetherketone (PEEK), and polyaromaticsulfones (PES) can be used as the precursor and converted into a carbon nanotube carbonaceous composition by exposure to elevated temperatures. Suitable precursor materials are disclosed in U.S. Pat. Nos. 6,673,953, 6,846,345, and 6,884,861 and in US Patent Application Publication Nos. 2003-0108477 and 2006-0130609. The precursor materials are either physically mixed with or coated in solution with metal salts, metallocenes, or other transition metal compounds that decompose upon thermal treatment yielding metal atoms, clusters, and/or nanoparticles. Depending on the precursor material, film, fiber, and shaped solid carbon nanotube compositions can be easily formulated by the method. Polyacrylonitrile and the pitches are commercially available and are currently used in the fabrication of carbon and graphite fibers, respectively. Phenolic resins are used as the matrix material in the formulation of carbon-carbon composites. Films, fibers, and shaped components of the material can be readily obtained. Carbon nanotube fibers may be made from inexpensive precursors that are presently being used to spin commercial fibers. The method may be used as an inexpensive method for the formation iii situ of carbon nanotubes using existing commercial materials. This method may permit the development of applications pertaining to purified carbon nanotubes within a shaped solid. This method may potentially increase the importance of carbon nanotubes for microelectronic, electrical, magnetic, battery, fuel cell, solar cell, electrochemical capacitors, hydrogen storage, catalytic, and structural applications.
• The synthetic strategy adds to the prior chemical synthesis of carbon nanotubes in high yield and in bulk carbonaceous solids from heat treatment of transition metal complexes of aromatic-based compounds, transition metal salts and aromatic compounds, and organometallic-containing aromatic compounds above 500° C. (FIG. 1). Any high performance compound or polymer containing a high proportion of aromatic units or aromatic precursors that char or retain weight upon heat treatment at elevated temperatures may afford carbon nanotubes in the presence of the appropriate transition metal. A number of the precursor compounds and polymers are commercially available. Studies have shown that only metal nanoparticles that are generated in situ and that chemically interact with the precursor organic materials during the heat treatment can be used to form carbon nanotubes within the charred carbonaceous compositions. The metal nanoparticle size and concentration can be changed by varying the concentration of precursor material and organometallic compound or metal salt. Some of the carbonaceous non-magnetic metal nanoparticle compositions exhibit superconductive properties.
• One goal can be to purify and to eliminate undesirable materials within the carbonaceous solid yielding a nanostructure mainly consisting of carbon nanotubes. The metal nanoparticles may be present in only catalytic amount depending on the metal concentration in the precursor composition. Micrographic analysis reveals that the as-prepared bulk carbonaceous solids contain a high fraction of multi-walled carbon nanotubes (MWNTs), which are embedded in a relatively dense solid of amorphous carbon (seeFIG. 2), with very low surface areas (<10 m²/g) for the overall composite. A selective combustion process can be used to achieve more porous and purified MWNT structures, essentially eliminating the amorphous carbon phase (seeFIG. 2(b)). In essence, the amorphous carbon component can be used as a porogen (i.e., pore forming agent) that can be selectively removed in this case by calcination at 480° C. to yield a highly porous carbon nanotube solid. The effects of this calcination procedure were further confirmed by N₂-sorption measurements, which demonstrated that the calcination of a Ni-catalyzed bulk carbon solid at ˜430° C. increases the specific surface areas from 10 m²/g up to 430 m²/g, while also introducing networks of mesopores and small macropores with cumulative pore volumes of up to 0.80 cm³/g. X-ray diffraction (FIG. 3) studies have confirmed that the selective combustion process removes the amorphous carbon phase while preserving the nanotubes. Depending on the precursor system and application, fibers, films, powders, and matrix components can be formulated and purified by the method.
• Carbon nanotubes synthesized by CVD and other reported methods occur from the vapor phase yielding impure carbon nanotubes in soot. As formed, the disclosed carbon nanotube-containing carbonaceous solids may contain much less metal relative to the CVD and other methods. The amorphous carbon can be removed from the soot by a calcination procedure yielding purified carbon nanotubes as a powdered composition. In contrast to the other methods, large amounts of carbon nanotubes can be formulated inexpensively by the presently disclosed method during the carbonization process in a solid configuration. The metal nanoparticles formed during the creation of the carbon nanotubes may be oxidized to the metal oxide during the calcination procedure. A potential advantage of this approach is that shaped solid components, fibers, and films can be readily fabricated from the melt or amorphous state of the precursor compounds. This method permits the removal of the amorphous carbon from the solid carbon containing the nanotubes, which enhances the importance of the carbon nanotubes for battery, fuel cell, membrane, microelectronic, sensor, solar, hydrogen storage, and structural applications. Depending on the formulation parameters, the physical properties of the purified carbonaceous material can be varied for potential magnetic, electrical, structural, catalytic, and medical applications.
• The shaped product (solid, film, or fiber) remaining after the calcination process can contain high purity carbon nanotubes with some metal nanoparticles as oxides, whose concentration can be easily varied. Since carbon nanotubes and transition metal nanoparticles are homogeneously dispersed in varying amounts in the carbonaceous shaped compositions, new technologies based on the carbon nanotube and carbon nanotube metal oxide nanoparticles can be readily developed from the materials of this invention.
• A variety of transition metal compounds, transition metal salts, and organic compounds may be used. Suitable transition metal compounds include, but are not limited to, organometallic compound, transition metal salt, octacarbonyl dicobalt, nonacarbonyl diron, biscyclooctadiene nickel, ferrocenylethynyl phenylethynylbenzene, and combinations thereof. The organic compound may comprise an aromatic group, an ethynyl group, aromatic precursor, and combinations thereof. Aromatic precursors are compounds that can be converted to aromatic compounds, such as an aromatic polymer, polyacrylonitrile. Suitable organic compounds include, but are not limited to, a phthalonitrile-terminated polymer, a phthalonitrile-terminated bisphenol A-benzophenone polymer, a cyanate ester-terminated aromatic polymer, a cyanate ester-terminated bisphenol A-benzene polymer, an aromatic epoxy, a polyether sulfone, a polyetheretherketone, a phenolic polymer, an aromatic polyimide, a polyphenylene sulfide, a polycarbonate, coal pitch, petroleum pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, and combinations thereof. The precursor composition may comprise a metal salt and an aromatic compound or polymer. More than one salt may be used in combination as long as at least one of the salts is a transition metal salt. One suitable non-transition metal salt is an aluminum salt.
• A single compound may serve as both the transition metal compound and the organic compound, such as a metal-ethynyl complex-containing compound. Such compounds may be made by, for example, reacting a metal carbonyl with an ethynyl compound such as 1,2,4,5-tetrakis(phenylethynyl)benzene.
• The carbon composition may be made by heating precursor composition under a non-oxidizing atmosphere or a reducing atmosphere and under thermal conditions effective to form the carbon composition comprising carbon nanotubes and amorphous carbon. Such conditions are disclosed in U.S. Pat. Nos. 6,673,953, 6,846,345, and 6,884,861 and in US Patent Application Publication Nos. 2003-0108477 and 2006-0130609 and include, but are not limited to, at least about 500° C., at least about 1000° C., and from about 800 to about 1300° C. under nitrogen. The presence of carbon nanotubes may be verified by, for example, SEM and/or X-ray diffraction. The carbon composition is then calcined to remove the amorphous carbon to leave behind carbon nanotubes. This may be done, for example, by heating under oxygen to a temperature of from about 400° C. to about 500° C. Removal of the amorphous carbon may be verified by, for example, SEM and/or X-ray diffraction. The resulting carbon nanotube composition may be a porous, solid material and may be in the form of a fiber, film, or shaped solid component.
• The carbon nanotube composition may contain nanoparticles of metal oxide. In may be desirable to reduce these nanoparticles to metal. This may be done by further processing the carbon nanotube composition by heating under a non-oxidizing or reducing atmosphere and under thermal conditions effective to reduce a metal oxide in the carbon nanotube composition to metal. Suitable conditions include, but are not limited to, heating under hydrogen to a temperature of from about 500 to about 800° C.
• Having described the invention, the following examples are given to illustrate specific applications of the invention. These specific examples are not intended to limit the scope of the invention described in this application.
Example 1
• Synthesis of 1:20 molar octacarbonyldicobalt/polyacrylonitrile mixture—Co₂(CO)₈(50 mg, 0.146 mmol), polyacrylonitrile (1.00 g), and 10 mL of methylene chloride were added to a 50 mL round bottomed flask. The polyacrylonitrile did not dissolve. The slurry was allowed to stir for 5 min before the solvent was removed under reduced pressure. The mixture was vacuum dried and isolated as an off-white solid.
Example 2
• Thermal conversion of 1:20 molar octacarbonyldicobalt/polyacrylonitrile mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/polyacrylonitrile mixture (22.8 mg) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 36%. The differential thermal analysis (DTA) curve showed an exotherm at 308° C. X-ray diffraction (XRD) studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes is readily apparent.
Example 3
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/polyacrylonitrile mixture—The composition from Example 2 (15 mg) was heated in a TGA chamber at 10° C./min to 410° C. and isothermed for 4 hours under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 4
• Synthesis of 1:100 molar octacarbonyldicobalt/polyacrylonitrile mixture—Co₂(CO)₈(10 mg, 0.0292 mmol), polyacrylonitrile (1.00 g), and 10 mL of methylene chloride were added to a 50 mL round bottomed flask. The polyacrylonitrile did not dissolve. The slurry was allowed to stir for 5 min before the solvent was removed under reduced pressure. The mixture was vacuum dried and isolated as an off-white solid.
Example 5
• Thermal conversion of 1:100 molar octacarbonyldicobalt/polyacrylonitrile mixture to carbon nanotube-cobalt nanoparticle composition—A 1:100 molar octacarbonyldicobalt/polyacrylonitrile mixture (25.32 mg) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 35%. The DTA curve showed an exotherm at 295° C. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 6
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:100 molar octacarbonyldicobalt/polyacrylonitrile mixture—The composition from Example 5 (20 mg) was heated in a TGA chamber at 10° C./min to 410° C. and isothermed for 6 hours under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 7
• Synthesis of 1:20 molar 1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile mixture—1-(ferrocenylethynyl)-3-(phenylethynyl)benzene (10 mg, 0.0259 mmol), polyacrylonitrile (500 mg), and 10 mL of methylene chloride were added to a 50 mL round bottomed flask. The polyacrylonitrile did not dissolve. The slurry was allowed to stir for 5 min before the solvent was removed under reduced pressure. The mixture was vacuum dried and isolated as an orange solid.
Example 8
• Thermal conversion of 1:20 molar 1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile mixture to carbon nanotube-iron nanoparticle composition—A 1:20 molar 1-(ferrocenylethynyl)-3-(phenylethynyl)-benzene/polyacrylonitrile mixture (30.26 mg) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 33%. The DTA curve showed an exotherm at 297° C. XRD studies confirmed the presence of carbon nanotubes-iron nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for iron nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 9
• Calcination of the carbon nanotube-iron nanoparticle composition in air prepared from a 1:20 molar 1-(ferrocenylethynyl)-3-(phenylethynyl)benzene/polyacrylonitrile mixture—The composition from Example 8 (20 mg) was heated in a TGA chamber at 10° C./min to 425° C. and isothermed for 4 hours under air. XRD studies confirmed the presence of carbon nanotubes-iron nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for iron nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 10
• Synthesis of 1:20 molar octacarbonyldicobalt/phthalonitrile mixture—The phthalonitrile resin (a 2:1 oligomer of bisphenol A and benzophenone capped with phthalonitrile units) (200 mg, 0.225 mmol) was dissolved in 10 mL of methylene chloride in a 25 mL round bottomed flask. Co₂(CO)₈(10 mg, 0.0292 mmol) dissolved in 2 mL of hexanes was added and a brown precipitate formed. The solvent was removed under reduced pressure, the mixture vacuum dried, and the product isolated as a dark brown solid.
Example 11
• Thermal conversion of 1:20 molar octacarbonyldicobalt/phthalonitrile mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/phthalonitrile mixture (38.01 mg) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 47%. The DTA curve showed exotherms at 163, 276, 514 and 868° C. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 12
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/phthalonitrile mixture—The composition from Example 11 (20 mg) was heated in a TGA chamber at 10° C./min to 445° C. and isothermed for 5 hours under air. XRD studies confirmed the presence of carbon nanotubes-iron nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The X-ray diffraction study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for iron nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 13
• Thermal conversion of 1:20 molar octacarbonyldicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyl-dicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone mixture (100 mg) was melted with bis[4-(3-aminophenoxy)phenyl]sulfone (2 mg) at 180° C. The mixture was cooled and a sample cured under nitrogen in a TGA chamber by heating at 250° C. for 1 h, 300° C. for 2 h, 350° C. for 6 h, and 375° C. for 4 h. The shaped composition was cooled and heated under nitrogen at 10° C./min to 1000° C. resulting in a char yield of 67%. The DTA curve showed exotherms at 530 and 751° C. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 14
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/phthalonitrile/bis[4-(3-aminophenoxy)phenyl]sulfone mixture—The composition from Example 13 (20 mg) was heated in a TGA chamber at 10° C./min to 425° C. and isothermed for 10 hours under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 15
• Synthesis of 1:20 molar octacarbonyldicobalt/cyanate ester mixture—A cyanate ester resin (a 2:1 oligomer of bisphenol A and 1,3-dibromobenzene terminated with cyanate ester units) (1.09 g, 1.88 mmol) was dissolved in 10 mL of methylene chloride in a 25 mL round bottomed flask. Co₂(CO)₈(55 mg, 0.161 mmol) dissolved in 2 mL of hexanes was added. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as a blue oil.
Example 16
• Thermal conversion of 1:20 molar octacarbonyldicobalt/cyanate ester mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/cyanate ester mixture (31.38 mg) was cured under nitrogen in a TGA chamber by heating at 100° C. for 1 h, 150° C. for 2 h, 200° C. for 2 h, 300° C. for 2 h, and 350° C. for 1 h. The shaped composition was cooled and heated at 10° C./min to 1000° C. under nitrogen resulting in a char yield of 34%. The DTA curve showed exotherms at 549 and 810° C. The latter peak was assigned to the formation of carbon nanotubes. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 17
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/cyanate ester mixture—The composition from Example 16 (20 mg) was heated in a TGA chamber at 10° C./min to 420° C. and isothermed for 8 hours under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 18
• Synthesis of 1:20 molar octacarbonyldicobalt/epoxy mixture—The epoxy Novolac resin (supplied by The Dow Chemical Company) (2.34 g), 1,3-bis(3-aminophenoxy)-benzene (1.17 g, 4.00 mmol), and Co₂(CO)₈(175 mg, 0.513 mmol) were dissolved in 10 mL of methylene chloride in a 25 mL round bottomed flask. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as a blue oil.
Example 19
• Thermal conversion of 1:20 molar octacarbonyldicobalt/epoxy mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/epoxy mixture (56.16 mg) was cured under nitrogen in a TGA chamber by heating at 80° C. for 2 h, 100° C. for 1 h, 150° C. for 1 h, 200° C. for 1 h, and 250° C. for 1 h. The shaped composition was cooled and heated at 10° C./min to 1000° C. under nitrogen resulting in a char yield of 23%. The DTA curve showed an exotherm at 831° C. attributed to the formation of carbon nanotubes. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 20
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/epoxy mixture—The composition from Example 19 (20 mg) was heated in a TGA chamber at 110° C./min to 420° C. and isothermed for 10 hours under air. X-ray studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbon composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The X-ray diffraction study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 21
• Synthesis of 1:20 molar octacarbonyldicobalt/polyethersulfone mixture—The polyethersulfone (200 mg) and Co₂(CO)₈(10 mg, 0.0292 mmol) were dry mixed and pulverized for 5 min in a Wiggle-Bug.
Example 22
• Thermal conversion of 1:20 molar octacarbonyldicobalt/polyethersulfone mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/polyethersulfone mixture (39.49 mg) was heated in a TGA chamber at 10° C./min to 1000° C. under nitrogen resulting in a shaped composition and a char yield of 44%. The DTA curve showed an exotherm at 581° C. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 23
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/polyethersulfone mixture—The composition from Example 22 (20 mg) was heated in a TGA chamber at 10° C./min to 460° C. and isothermed for 1 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 24
• Synthesis of 1:20 molar octacarbonyldicobalt/polyetheretherketone (PEEK) mixture—The PEEK (200 mg) and Co₂(CO)₈(10 mg, 0.0292 mmol) were dry mixed and pulverized for 5 min in a Wiggle-Bug.
Example 25
• Thermal conversion of 1:20 molar octacarbonyldicobalt/PEEK mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/PEEK mixture (35.25 mg) was heated in a TGA chamber at 10° C./min to 1000° C. under nitrogen resulting in a shaped composition and a char yield of 42%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The X-ray diffraction study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 26
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/PEEK mixture—The composition from Example 25 (20 mg) was heated in a TGA chamber at 10° C./min to 450° C. and isothermed for 2 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 27
• Synthesis of 1:20 molar octacarbonyldicobalt/phenolic resin mixture—The phenolic resin (1.00 g) (a Novolac-type phenol-formaldehyde polymer), octamethylenetetramine (80 mg, 0.571 mmol) and Co₂(CO)₈(50 mg, 0.146 mmol) were mixed together in 10 mL of methylene chloride. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as brown solid.
Example 28
• Thermal conversion of a 1:20 molar octacarbonyldicobalt/phenolic resin mixture to a carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/phenolic resin mixture (23 mg) was cured under nitrogen in a TGA chamber by heating at 150° C. for 2 h, 200° C. for 2 h, 300° C. for 1 h, and 350° C. for 1 h. The shaped composition was cooled and heated at 10° C./min to 1000° C. under nitrogen resulting in a char yield of 50%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The X-ray diffraction study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 29
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/phenolic resin mixture—The composition from Example 28 (20 mg) was heated in a TGA chamber at10C/min to 450° C. and isothermed for 2 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 30
• Synthesis of 1:20 molar octacarbonyldicobalt/polyimide mixture—The polyimide monomer (500 mg) (Thermid 600) and Co₂(CO)₈(25 mg, 0.0730 mmol) were mixed together in 10 mL of methylene chloride. The polyimide did not dissolve. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as a brown solid.
Example 31
• Thermal conversion of a 1:20 molar octacarbonyldicobalt/polyimide mixture to a carbon nanotube-cobalt nanoparticle composition—A sample of the mixture polyimide monomer and Co₂(CO)₈was cured under nitrogen in a TGA chamber by heating at 315° C. for 3 h. The shaped composition was cooled and heated at 10° C./min to 1000° C. under nitrogen resulting in a char yield of 60%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 32
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/polyimide mixture—The composition from Example 31 (20 mg) was heated in a TGA chamber at 10° C./min to 455° C. and isothermed for 4 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 33
• Synthesis of 1:20 molar octacarbonyldicobalt/polyphenylene sulfide mixture—The powdered poly(1,4-phenylene sulfide) (1.00 g) and Co₂(CO)₈(50 mg, 0.146 mmol) were mixed together in 5 mL of methylene chloride. The heterogeneous mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated.
Example 34
• Thermal conversion of a 1:20 molar octacarbonyldicobalt/polyphenylene sulfide mixture to a carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/polyphenylene sulfide (35 mg) was heated at 10° C./min to 1000° C. tinder nitrogen resulting in a shaped component with a char yield of 40%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 35
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/polyphenylene sulfide—The composition from Example 34 (20 mg) was heated in a TGA chamber at10C/min to 455° C. and isothermed for 4 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 36
• Synthesis of 1:20 molar octacarbonyldicobalt/polycarbonate mixture—The powdered poly(bisphenol A carbonate) (2.00 g) and Co₂(CO)₈(100 mg, 0.293 mmol) were mixed together in 5 mL of methylene chloride. The heterogeneous mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated.
Example 37
• Thermal conversion of a 1:20 molar octacarbonyldicobalt-/polycarbonate mixture to a carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/polycarbonate mixture (22.48 mg) was heated at 10° C./min to 1000° C. under nitrogen resulting in a shaped component with a char yield of 35%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 38
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt-/polycarbonate mixture—The composition from Example 37 (20 mg) was heated in a TGA chamber at 10° C./min to 425° C. and isothermed for 14 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis showed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 39
• Synthesis of 1:20 molar octacarbonyldicobalt/coal pitch mixture—The coal tar pitch (1.18 g) and Co₂(CO)₈(59 mg, 0.172 mmol) were mixed together in 5 mL of methylene chloride. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as a black oil.
Example 40
• Thermal conversion of a 1:20 molar octacarbonyldicobalt/coal pitch mixture to a carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/coal pitch mixture (46 mg) was heated at 10° C./min to 1000° C. under nitrogen resulting in a shaped component with a char yield of 30%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 41
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/coal pitch mixture—The composition from Example 40 (20 mg) was heated in a TGA chamber at 10° C./min to 420° C. and isothermed for 10 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis showed a reduction in the amorphous carbon. SEM studies confirmed the presence of pores in the sample. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 42
• Synthesis of 1:20 molar octacarbonyldicobalt/petroleum pitch mixture—The petroleum pitch (1.05 g) and Co₂(CO)₈(53 mg, 0.154 mmol) were mixed together in 5 mL of methylene chloride. The mixture was stirred for 5 min and the solvent was removed under reduced pressure. The mixture was vacuum dried and the product isolated as a black oil.
Example 43
• Thermal conversion of a 1:20 molar octacarbonyldicobalt/petroleum pitch mixture to a carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/petroleum pitch mixture (52 mg) was heated at 10° C./min to 1000° C. under nitrogen resulting in a shaped component with a char yield of 29%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt and cobalt oxide nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 44
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air prepared from a 1:20 molar octacarbonyldicobalt/petroleum pitch mixture—The composition from Example 43 (20 mg) was heated in a TGA chamber at 10° C./min to 440° C. and isothermed for 3 hour under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis showed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 45
• Synthesis of 1:20 hexacarbonyldicobalt complex of 1,2,4,5-tetrakis(phenylethynyl)benzene—Co₂(CO)₈(0.1 g, 0.29 mmol) and 75 mL of dry hexane were added to a 100 mL round bottomed flask. While stirring, the mixture was cooled to −78° C., evacuated, and purged with argon three times to remove air. 1,2,4,5-Tetrakis(phenylethynyl)benzene (2.8 g, 5.8 mmol) dissolved in 100 mL of methylene chloride was added by syringe resulting in the formation a white precipitate. The mixture turned yellow, was allowed to warm to room temperature, and was stirred for 3 hr resulting in dissolution of the solid and a color change to dark green. The formation of the green solution is apparently due to the reaction of the Co₂(CO)₈with an alkyne group of 1,2,4,5-tetrakis(phenylethynyl)benzene. The solvent was removed at reduced pressure. The product was used as prepared for characterization studies.
Example 46
• Thermal conversion of 1:20 molar octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene mixture to carbon nanotube-cobalt nanoparticle composition—A 1:20 molar octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene mixture (20 mg) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 80%. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 47
• Calcination of the carbon nanotube-cobalt nanoparticle composition in air 1:20 molar octacarbonyldicobalt/1,2,4,5-tetrakis(phenylethynyl)benzene mixture—The composition from Example 46 (15 mg) was heated in a TGA chamber at 10° C./min to 420° C. and isothermed for 30 min under air. XRD studies confirmed the presence of carbon nanotubes-cobalt nanoparticles in the carbonaceous composition. XRD analysis showed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for cobalt nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 48
• Thermal conversion of 1:20 molar Ni(COD)₂/1,2,4,5-tetrakis(phenylethynyl)benzene mixture to carbon nanotube-nickel nanoparticle composition—A 1:20 molar bis (cyclooctadiene) nickel (Ni(COD)₂)/1,2,4,5-tetrakis(phenylethynyl)benzene mixture (35 mg) (prepared from 1.7 g (3.6 mmol, 20 equiv) of 1,2,4,5-tetrakis(phenylethynyl)benzene and 0.05 g, (0.18 mmol, 1 equiv) of Ni(COD)₂, by mixing in a solution of 65 mL of hexane and 65 mL of CH₂Cl₂, and concentrating to dryness) was heated in a TGA chamber under nitrogen at10C/min to 1300° C. resulting in a shaped composition and a char yield of 80%. XRD studies confirmed the presence of carbon nanotubes-nickel nanoparticles in the carbonaceous composition. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for nickel nanoparticles.FIG. 1 shows a SEM studies on the surface of the surface of the bulk sample. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 49
• Calcination of the carbon nanotube-nickel nanoparticle composition in air prepared from 1:20 molar Ni(COD)₂/1,2,4,5-tetrakis(phenylethynyl)benzene mixture—The composition from Example 48 (15 mg) was heated in a TGA chamber at 10° C./min to 425° C. and isothermed for 2 hours under air. XRD studies confirmed the presence of carbon nanotubes-nickel nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon (seeFIG. 3). SEM studies confirmed the presence of pores in the sample (seeFIG. 2). The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for nickel nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 50
• Thermal conversion of 1:20 molar Fe₂(CO)₉/1,2,4,5-tetrakis(phenylethynyl)benzene mixture to carbon nanotube-nickel nanoparticle composition—A 1:20 molar Fe₂(CO)₉/1,2,4,5-tetrakis(phenylethynyl)benzene mixture (52 mg) (prepared from 1,2,4,5-tetrakis(phenylethynyl)benzene (0.10 g, 0.21 mmol) and Fe₂(CO)₉(0.0038 g, 0.0104 mmol) by mixing in a solution of 65 mL of hexane and 65 mL of CH₂Cl₂, and concentrating to dryness) was heated in a TGA chamber under nitrogen at 10° C./min to 1000° C. resulting in a shaped composition and a char yield of 83%. XRD studies confirmed the presence of carbon nanotubes-iron nanoparticles in the carbonaceous composition. The X-ray diffraction study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for iron nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 51
• Calcination of the carbon nanotube-nickel nanoparticle composition in air prepared from 1:20 molar Fe₂(CO)₉/1,2,4,5-tetrakis(phenylethynyl)benzene mixture—The composition from Example 50 (15 mg) was heated in a TGA chamber at 10° C./min to 400° C. and isothermed for 20 hours min under air. XRD studies confirmed the presence of carbon nanotubes-nickel nanoparticles in the carbonaceous composition. XRD analysis confirmed a reduction in the amorphous carbon. The XRD study showed the four characteristic reflections [(002), (100), (004), and (110)] values for carbon nanotubes and the pattern for iron nanoparticles. The X-ray (002) reflection for carbon nanotubes was readily apparent.
Example 52
• Thermal Processing Of As-Pyrolyzed Carbon Nanotube Solids—Following the carbonization process, the carbon solid is heated in either air or O₂(static or flowing) to temperatures ranging from 400-520° C., to remove amorphous carbon via selective combustion, while leaving the carbon nanotube phase intact. The exact processing conditions for this selective combustion process are determined by first characterizing the carbon solid by thermogravimetric analysis and differential scanning calorimetric under flowing air or O₂. The selective combustion process also converts the metal catalyst from its metallic to its oxide form, as shown in the XRD patterns inFIG. 3 for a Ni-catalyzed CNT solid. A subsequent thermal treatment under reducing conditions (flowing H₂or vacuum) can be used to convert the metal oxide phase back to its metallic form.
Example 53
• Reduction Of Metal Oxide Formed During Calcination To Elemental Metal—Following the selective combustion process to remove the amorphous content from the bulk carbon nanotube solid, the material formed in Example 52 can be subjected to an additional thermal treatment under de-oxygenating conditions, for the purpose of reducing the oxidized metal catalyst back to its original metallic form, and also reducing carbon-oxygen functional groups that form on the nanotube surface during the selective combustion purification. Typically the carbon nanotube solid would be heated under dilute or pure hydrogen at temperatures from 500-800° C. for several hours. Alternatively the carbon nanotube solid could be heated under vacuum at similar temperatures to de-oxygenate and reduce metal oxides and oxidized carbon functionalities in the material.
• Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that the claimed invention may be practiced otherwise than as specifically described. Any reference to claim elements in the singular, e.g., using the articles “a,” “an,” “the,” or “said” is not construed as limiting the element to the singular.

Claims (24)

1. A carbon nanotube composition made by:

heating a precursor composition under a non-oxidizing or reducing atmosphere and under thermal conditions effective to form a carbon composition comprising carbon nanotubes and amorphous carbon;

wherein the precursor composition comprises a mixture or complex of:

a transition metal compound; and

an organic compound that chars at elevated temperatures; and

calcining the carbon composition in the presence of oxygen under thermal conditions that oxidize and vaporize the amorphous carbon without oxidizing the carbon nanotubes.

2. The carbon nanotube composition ofclaim 1, wherein heating the precursor composition comprises heating the precursor composition under nitrogen to a temperature of at least about 500° C.

3. The carbon nanotube composition ofclaim 1, wherein calcining the carbon composition comprises heating the carbon composition under oxygen to a temperature of from about 400° C. to about 500° C.

4. The carbon nanotube composition ofclaim 1, wherein the transition metal compound is an organometallic compound, a transition metal salt, octacarbonyl dicobalt, nonacarbonyl diron, biscyclooctadiene nickel, ferrocenylethynyl phenylethynylbenzene, or a combination thereof.

5. The carbon nanotube composition ofclaim 1, wherein the organic compound comprises an aromatic group, an ethynyl group, aromatic precursor, or a combination thereof.

6. The carbon nanotube composition ofclaim 1, wherein the organic compound is an aromatic-containing polymer, polyacrylonitrile, a phthalonitrile-terminated polymer, a phthalonitrile-terminated bisphenol A-benzophenone polymer, a cyanate ester-terminated aromatic polymer, a cyanate ester-terminated bisphenol A-benzene polymer, an aromatic epoxy, a polyether sulfone, a polyetheretherketone, a phenolic polymer, an aromatic polyimide, a polyphenylene sulfide, a polycarbonate, coal pitch, petroleum pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, or a combination thereof.

7. The carbon nanotube composition ofclaim 1, wherein the precursor composition comprises a metal-ethynyl complex-containing compound.

8. The carbon nanotube composition ofclaim 1, wherein the precursor composition comprises a transition metal salt and an aromatic compound or a polymer.

9. The carbon nanotube composition ofclaim 1, wherein carbon nanotube composition is a porous, solid material; a film; a fiber; or a shaped solid component.

10. A reduced carbon nanotube composition made by:

heating the carbon nanotube composition ofclaim 1 under a non-oxidizing or reducing atmosphere and under thermal conditions effective to reduce a metal oxide in the carbon nanotube composition to metal.

11. The reduced carbon nanotube composition ofclaim 10, wherein heating the carbon nanotube composition comprises heating the carbon nanotube composition under hydrogen to a temperature of from about 500 to about 800° C.

12. The reduced carbon nanotube composition ofclaim 10, wherein heating the carbon nanotube composition comprises heating the carbon nanotube composition under a vacuum.

13. A method comprising:

heating a precursor composition under a non-oxidizing or reducing atmosphere and under thermal conditions effective to form a carbon composition comprising carbon nanotubes and amorphous carbon;

wherein the precursor composition comprises a mixture or complex of:

a transition metal compound; and

an organic compound that chars at elevated temperatures; and

calcining the carbon composition in the presence of oxygen under thermal conditions that oxidize and vaporize the amorphous carbon without oxidizing the carbon nanotubes.

14. The method ofclaim 13, wherein heating the precursor composition comprises heating the precursor composition under nitrogen to a temperature of at least about 500° C.

15. The method ofclaim 13, wherein calcining the carbon composition comprises heating the carbon composition under oxygen to a temperature of from about 400° C. to about 500° C.

16. The method ofclaim 13, wherein the transition metal compound is an organometallic compound, a transition metal salt, octacarbonyl dicobalt, nonacarbonyl diron, biscyclooctadiene nickel, ferrocenylethynyl phenylethynylbenzene, or a combination thereof.

17. The method ofclaim 13, wherein the organic compound comprises an aromatic group, an ethynyl group, aromatic precursor, or a combination thereof.

18. The method ofclaim 13, wherein the organic compound is an aromatic-containing polymer, polyacrylonitrile, a phthalonitrile-terminated polymer, a phthalonitrile-terminated bisphenol A-benzophenone polymer, a cyanate ester-terminated aromatic polymer, a cyanate ester-terminated bisphenol A-benzene polymer, an aromatic epoxy, a polyether sulfone, a polyetheretherketone, a phenolic polymer, an aromatic polyimide, a polyphenylene sulfide, a polycarbonate, coal pitch, petroleum pitch, 1,2,4,5-tetrakis(phenylethynyl)benzene, or a combination thereof.

19. The method ofclaim 13, wherein the precursor composition comprises a metal-ethynyl complex-containing compound.

20. The method ofclaim 13, wherein the precursor composition comprises a transition metal salt and an aromatic compound or a polymer.

21. The method ofclaim 13, wherein carbon nanotube composition is a porous, solid material; a film; a fiber; or a shaped solid component.

22. The method ofclaim 13, further comprising

heating the product of calcining the carbon composition under a non-oxidizing or reducing atmosphere and under thermal conditions effective to reduce a metal oxide in the product of calcining the carbon composition to metal.

23. The method ofclaim 22, wherein heating the product of calcining the carbon composition comprises heating the product of calcining the carbon composition under hydrogen to a temperature of from about 500 to about 800° C.

24. The method ofclaim 22, wherein heating the carbon nanotube composition comprises heating the carbon nanotube composition under a vacuum.

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