JPWO2018105559A1 - Carbon material, method for producing the same, and electron emission material - Google Patents

Abstract

A carbon material having excellent electrical conductivity, a method for producing the same, and an electron emission material are provided. The carbon material according to the present invention is a carbon material having a carbon six-membered ring network, and a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are respectively incorporated in the carbon six-membered ring network. It is characterized by.

Description

  The present invention relates to a carbon material, a method for producing the same, and an electron emission material, and more particularly, to an electronic device such as an emitter of a field electron emission display (FED), a field effect transistor, a cathode ray tube, and an electron gun. The present invention relates to a carbon material, a manufacturing method thereof, and an electron emission material.

  Single-walled carbon nanotubes (hereinafter sometimes referred to as “SWCNT”) are hollow cylindrical carbon materials composed only of carbon atoms, and because of their characteristic structure, they have excellent mechanical properties and electrical properties. Shows conductivity. Further, SWCNT has a unique property that it can be either a metal type or a semiconductor type depending on the winding method (chirality). In particular, it is expected to be applied to nanowiring, ultralight wires, and other electronic devices by taking advantage of its excellent electrical conductivity, but has not yet been realized.

  One of the causes is that structural defects are introduced into the carbon skeleton during the SWCNT synthesis process, purification process, or surface chemical modification process. This is because structural defects cause a decrease or change in some properties including the electrical conductivity of SWCNTs. As a result, research and development of SWCNTs that do not have structural defects are underway, but there is a problem that their synthesis is difficult. The structural defects mentioned here are introduced functional groups, STW (Stone-Thrower-Wales) defects, and atoms other than carbon atoms (for example, hydrogen atoms, oxygen atoms, nitrogen atoms, metal atoms, etc.). It means defects due to existence, vacancy defects, and the like.

S.Iijima, Nature Vol.354, p.56 (1991)

  The present invention has been made in view of the above problems, and an object thereof is to provide a carbon material excellent in electrical conductivity, a manufacturing method thereof, and an electron emission material.

  The inventors of the present application do not prevent the occurrence of vacancy defects when putting carbon materials such as SWCNTs into practical use, but actively utilize the vacancy defects, thereby providing characteristics such as electrical conductivity. As a result, the present invention has been completed.

  That is, in order to solve the above problems, the carbon material of the present invention is a carbon material having a carbon six-membered ring network, and a carbon five-membered ring structure that is a rearranged structure in the carbon six-membered ring network. And a carbon seven-membered ring structure.

  In the above configuration, the carbon material having the carbon six-membered ring network is a carbon nanotube, and the carbon five-membered ring structure and the carbon seven-membered ring structure, which are the rearranged structures, are provided on at least side surfaces of the carbon nanotube. It is preferably incorporated.

  In the above configuration, the carbon nanotube is preferably a zigzag single-walled carbon nanotube, an armchair single-walled carbon nanotube, or a chiral single-walled carbon nanotube.

  In the above configuration, the carbon material having the carbon six-membered ring network is preferably graphene.

  In order to solve the above-described problem, a method for producing a carbon material according to the present invention comprises bringing a treatment gas containing a fluorine-containing gas into contact with a carbon material having a carbon six-membered ring network, and applying fluorine to the surface of the carbon material. A fluorination treatment step for introducing a group, and a carbon material after the fluorination treatment step is annealed under conditions of a temperature of 400 ° C. to 1500 ° C. And an annealing treatment step for introducing a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, respectively.

  In the above-described configuration, carbon nanotubes are used as the carbon material having the carbon six-membered ring network, and the carbon five-membered ring structure and the carbon seven-membered ring structure as the rearranged structure are converted into the carbon by the annealing treatment. It is preferable to introduce each into the side surface of the nanotube.

  In the above configuration, it is preferable to use a zigzag single-walled carbon nanotube, an armchair single-walled carbon nanotube, or a chiral single-walled carbon nanotube as the carbon nanotube.

  In the above configuration, graphene is preferably used as the carbon material having the carbon six-membered ring network.

  According to the carbon material of the present invention, a carbon five-membered ring structure and a carbon seven-membered ring structure are respectively incorporated in the carbon six-membered ring network constituting the carbon material. The carbon five-membered ring structure and the carbon seven-membered ring structure are structures in which the carbon atoms of the part where the vacancy defects are originally generated are rearranged. Therefore, the carbon material having the above-described configuration can improve electrical conductivity as compared with the carbon material having vacancy defects.

  Further, according to the method for producing a carbon material of the present invention, a fluorine gas is introduced to the surface of the carbon material by bringing a treatment gas containing a fluorine-containing gas into contact with the carbon material having a carbon six-membered ring network, thereby fluorinating. Process. Next, annealing is performed to desorb the fluorine group and cause a vacancy defect in the carbon six-membered ring network, and then rearrange the carbon atoms in the vacancy defect portion. As a result, a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are introduced into the carbon six-membered ring network, and a carbon material having excellent electrical conductivity can be produced.

It is the elements on larger scale showing the structure of a single wall carbon nanotube roughly, Comprising: The same figure (a) represents the case where a single wall carbon nanotube is a zigzag type, The same figure (b) is the said zigzag type single wall carbon. The figure shows a case where a rearranged structure is introduced into the nanotube. FIG. 10C shows the case where the single-walled carbon nanotube is an armchair type, and FIG. This represents the case where an array structure is introduced. It is explanatory drawing for demonstrating the manufacturing method of the carbon material which concerns on one Embodiment of this invention.

(Carbon material)
A carbon material according to an embodiment of the present invention will be described below.
The carbon material of the present embodiment has a carbon six-membered ring network, and further has a structure in which a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are respectively incorporated in the carbon six-membered ring network. By incorporating a carbon five-membered ring structure and a carbon seven-membered ring structure into a carbon six-membered ring network that is a carbon skeleton, the electrical conductivity of the carbon material can be improved.

  In the present invention, the “carbon six-membered ring network” means a carbon skeleton in which a six-membered ring structure (honeycomb structure) composed of only carbon atoms is used as a unit and the six-membered ring structure is bonded in a network. A “carbon six-membered ring network” is a framework that does not contain hydrogen atoms and substituents, and consists entirely of carbon atoms. In the present invention, the “rearrangement structure” means a structure formed by rearranging carbon atoms in a vacancy defect portion existing in the carbon six-membered ring network, and more specifically. Refers to a carbon five-membered ring structure and a carbon seven-membered ring structure. Further, the “vacancy defect” means a state in which, in the carbon six-membered ring network, a part of the carbon atoms constituting the network does not exist and a void is generated as a structural defect.

  The carbon material is not particularly limited as long as it has a carbon six-membered ring network composed of carbon atoms. For example, activated carbon, carbon nanocoil, graphite, carbon black, diamond-like carbon, carbon fiber, graphene, amorphous Carbon, fullerene, carbon nanotube and the like. Furthermore, analogs having such a basic structure of the carbon material are also included in the carbon material according to the present invention. Among these carbon materials, carbon nanotubes, graphene, and the like are preferable in the present embodiment. Fullerenes inherently have a carbon five-membered ring structure in addition to a carbon six-membered ring structure, and the carbon five-membered ring structure is a vacancy defect portion that was present in the carbon six-membered ring network. It is not formed by rearranging carbon atoms. Therefore, it is different from the carbon five-membered ring structure which is a rearranged structure in the present invention.

  When the carbon material is a carbon nanotube, the carbon five-membered ring structure and the carbon seven-membered ring structure, which are rearranged structures, are incorporated on at least the side surface of the carbon nanotube. By incorporating a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, on the side surfaces of the carbon nanotube, the electrical conductivity of the carbon nanotube can be improved.

  Examples of the carbon nanotubes include single-walled carbon nanotubes (SWCNTs) having a single hexagonal tube (graphene sheet), and multi-walled carbon nanotubes (MWCNTs) composed of multi-layered graphene sheets. : Fulli Wall Carbon Nanotube), fullerene tube, bucky tube, and graphite fibril.

  Furthermore, examples of single-walled carbon nanotubes include zigzag (metal) single-walled carbon nanotubes, armchair-type (semiconductor-type) single-walled carbon nanotubes, and chiral-type single-walled carbon nanotubes from the viewpoint of the arrangement of a six-membered ring structure. It is done.

  When the single-walled carbon nanotube is a zigzag type (metal type), the single-walled carbon nanotube before the rearrangement structure is introduced has a carbon six-membered ring network structure as shown in FIG. . When a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are introduced into the carbon six-membered ring network of the zigzag single-walled carbon nanotube, the structure shown in FIG. 1B is obtained. When the single-walled carbon nanotube is an armchair type (semiconductor type), the single-walled carbon nanotube before the rearrangement structure is introduced has a structure of a carbon six-membered ring network as shown in FIG. It has become. When a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are introduced into the carbon six-membered ring network of the armchair type single-walled carbon nanotube, the structure shown in FIG. . FIG. 1 is a partially enlarged view schematically showing the structure of a single-walled carbon nanotube, in which FIG. 1 (a) shows a case where the single-walled carbon nanotube is a zigzag type, and FIG. The case where the rearrangement structure is introduced into the zigzag type single-walled carbon nanotube is shown, FIG. 6C shows the case where the single-walled carbon nanotube is an armchair type, and FIG. This represents a case where a rearranged structure is introduced into the single-walled carbon nanotube.

  The single-walled carbon nanotube may have a structure in which one or both ends thereof are open, or may have a closed structure. In the case of a closed structure, a carbon five-membered ring structure is incorporated at the end of the single-walled carbon nanotube. In this case, the tip shape can be appropriately changed according to the number of carbon five-membered ring structures and the arrangement position. In addition, the carbon five-membered ring structure introduced in order to make the structure which closed the terminal of the single-walled carbon nanotube is not formed by rearranging the carbon atoms of the vacancy defect part. Therefore, it is different from the carbon five-membered ring structure which is a rearranged structure in the present invention.

(Method for producing carbon material)
Next, a method for manufacturing the carbon material according to the present embodiment will be described below with reference to FIG. FIG. 2 is an explanatory diagram for explaining a method for producing the carbon material.

  As shown in FIG. 2, the carbon material manufacturing method of the present embodiment includes at least a carbon material fluorination treatment step and an annealing treatment step of annealing the fluorinated carbon material.

  The fluorination treatment step is a step of subjecting the carbon material to a fluorination treatment in a gas phase by bringing a treatment gas containing at least a fluorine-containing gas into contact with the carbon material. For example, as shown in FIG. 2, when the carbon material is a single-walled carbon nanotube 11, this step introduces a fluorine group 12 by a carbon-fluorine bond on the surface of the single-walled carbon nanotube 11. This step is different from, for example, an oxidation treatment in which an oxygen-containing functional group such as a hydroxyl group, a carbonyl group, or a carboxyl group is added to the edge portion of the carbon hexagonal network surface, and structural defects such as damage or decomposition of the carbon material are performed. The surface can be fluorinated without causing it.

  As said process gas, what contains 0.01-100 vol%, Preferably it is 0.1-80 vol%, More preferably, 1-50 vol% of fluorine-containing gas is used with respect to the whole volume. By setting the concentration of the fluorine-containing gas to 0.01 vol% or more, the fluorination of the carbon material surface can be prevented from becoming insufficient.

The fluorine-containing gas means a gas containing a fluorine atom, and is not particularly limited in the present embodiment as long as it contains a fluorine atom. Examples of the fluorine-containing gas include fluorine (F ₂ ), hydrogen fluoride (HF), chlorine trifluoride (ClF ₃ ), sulfur tetrafluoride (SF ₄ ), boron trifluoride (BF ₃ ), three Examples thereof include nitrogen fluoride (NF ₃ ) and carbonyl fluoride (COF ₂ ). You may use these individually or in mixture of 2 or more types.

  The processing gas may contain an inert gas. The inert gas is not particularly limited, but those that react with the fluorine-containing gas and adversely affect the fluorination treatment of the carbon material, those that react with the carbon material and adversely affect, and those that contain impurities that adversely affect the carbon material It is not preferable. Specific examples include nitrogen, argon, helium, neon, krypton, and xenon. These may be used alone or in admixture of two or more. In addition, the purity of the inert gas is not particularly limited, but the impurities that have an adverse effect are preferably 100 ppm or less, more preferably 10 ppm or less, and particularly preferably 1 ppm or less.

  The processing gas preferably does not contain a gas containing oxygen atoms. This is because by containing a gas containing oxygen atoms, a hydroxyl group, a carboxyl group, or the like is introduced on the surface of the carbon material, and the carbon material may be seriously damaged. The gas containing oxygen atoms means oxygen gas or nitric acid gas.

  The method for contacting the processing gas is not particularly limited, and for example, it can be performed by contacting the carbon material under a processing gas flow or in an atmosphere of the processing gas in a sealed container.

  Although the processing temperature at the time of performing the said fluorination process is not specifically limited, Preferably it exists in the range of 0 degreeC-1500 degreeC, More preferably, it is 0 degreeC-800 degreeC, More preferably, it is 0 degreeC-600 degreeC. By setting the treatment temperature to 0 ° C. or higher, the fluorination treatment can be promoted. On the other hand, by setting the treatment temperature to 1500 ° C. or less, it is possible to suppress an excessive increase in defects in the carbon skeleton that accompanies the introduction of fluorine groups on the surface of the carbon material. It is possible to prevent the mechanical strength of the carbon material from decreasing. Furthermore, it is possible to prevent the carbon material from being thermally deformed and suppress a decrease in yield.

  The treatment time (reaction time) of the fluorination treatment is not particularly limited, but is in the range of 1 second to 24 hours, preferably 1 second to 12 hours, and more preferably 1 second to 9 hours. By setting the treatment time to 1 second or longer, the fluorination of the carbon material surface can be made sufficient. On the other hand, by setting the treatment time to 24 hours or less, it is possible to prevent a decrease in production efficiency due to an increase in production time.

  It does not specifically limit as a pressure condition at the time of performing a fluorination process, It can carry out under a normal pressure, pressurization, or pressure reduction. From the viewpoint of economy and safety, it is preferable to carry out under normal pressure. The reaction vessel for performing the fluorination treatment is not particularly limited, and conventionally known ones such as a fixed bed and a fluidized bed can be employed.

  It does not specifically limit as a contact method of the process gas with respect to a carbon material, For example, it can contact under the flow of the said process gas.

  The annealing treatment step is a step of heating the carbon material after the fluorination treatment step at a predetermined temperature. For example, in the case of the single-walled carbon nanotube 11 shown in FIG. 2, first, the fluorine group 12 introduced to the surface of the single-walled carbon nanotube 11 is desorbed to generate a vacancy defect 13 in the carbon six-membered ring structure. Thereafter, the carbon atoms in the vacancy defects 13 are rearranged to introduce the carbon five-membered ring structure 14 and the carbon seven-membered ring structure 15.

  The treatment temperature at the time of annealing treatment is in the range of 400 ° C to 1500 ° C, preferably 600 ° C to 1500 ° C, more preferably 800 ° C to 1500 ° C. By setting the annealing temperature to 400 ° C. or higher, the fluorine group can be sufficiently desorbed and the generation of the rearranged structure can be promoted. On the other hand, by setting the annealing temperature to 1500 ° C. or less, it is possible to suppress excessive introduction of new structural defects into the carbon six-membered ring network. It is possible to prevent a decrease in the mechanical strength. Furthermore, it is possible to prevent the carbon material from being thermally deformed and suppress a decrease in yield.

  The treatment time for performing the annealing treatment is not particularly limited, but is within the range of 1 second to 24 hours, preferably 1 second to 12 hours, and more preferably 1 second to 9 hours. By setting the treatment time to 1 second or longer, it is possible to sufficiently remove the fluorine group and promote the generation of a rearranged structure. On the other hand, deterioration of the carbon material can be prevented by setting the treatment time to 24 hours or less.

  The pressure condition for performing the annealing treatment is not particularly limited, but it is preferably performed under reduced pressure or high vacuum with respect to atmospheric pressure. By setting the pressure condition to be lower than the atmospheric pressure, it is possible to promote the generation of vacancy defects due to the elimination of the fluorine group. The atmospheric pressure means the pressure in the vicinity of the atmospheric standard state (standard atmospheric pressure), and the atmospheric standard state is the atmospheric pressure condition in which the temperature is approximately 25 ° C. and the absolute pressure is approximately 101 kPa. Means. Further, the “atmospheric pressure” includes a case where the pressure is slightly positive or negative with respect to the standard atmospheric pressure.

  In addition, the annealing treatment process has different treatment conditions for a stage in which a fluorine group is eliminated from a carbon material to cause vacancy defects and a stage in which a rearranged structure is introduced by rearranging carbon atoms. It may be allowed.

  In addition, it is desirable that the carbon material after the annealing treatment process does not have a fluorine group from the viewpoint of improving electrical conductivity. For example, the carbon material is provided with a function of improving dispersibility of the carbon material in a solvent. If desired, the fluorine group may remain within a range that does not affect the electrical conductivity.

  As described above, according to the manufacturing method of the present embodiment, it is possible to manufacture a carbon material in which a five-membered ring structure and a seven-membered ring structure that are rearranged structures are incorporated in a carbon six-membered ring network. Thereby, in this Embodiment, compared with the conventional carbon material which has a void defect, the carbon material excellent in electrical conductivity can be manufactured.

  The electrical conductivity of the carbon material is preferably improved by 10% or more in electrical conductivity (S / m) under reduced pressure relative to electrical conductivity (S / m) under atmospheric pressure, for example. , Preferably 20% or more, more preferably 40% or more.

(Electron emission material)
The carbon material of the present embodiment can be used as an electron emission material, for example. The electron emission material can be applied to an emitter of a field electron emission display (FED), a field effect transistor, a cathode ray tube, an electron gun and the like.

(Other)
In the present embodiment, the mode in which the annealing process is performed after the fluorination process has been described. However, the present invention is not limited to this embodiment. For example, the fluorination treatment and the annealing treatment may be performed simultaneously in one step. Thereby, the manufacturing time of a carbon material can be shortened. The processing conditions when the fluorination treatment and the annealing treatment are performed simultaneously are as described above.

Example 1
10 mg of armchair type (semiconductor type) single-walled carbon nanotubes were introduced into a PTFE (polytetrafluoroethylene) container (capacity 5 mL), and this container was placed in an electropolished chamber made of SUS316L (capacity 30 mL). A single-walled carbon nanotube having a structure in which both ends are closed was used. Further, the chamber was heated to 250 ° C. at a rate of 4 ° C./min under a nitrogen gas stream (20 mL / min), and then subjected to a constant temperature treatment at a temperature of 250 ° C. for 1 hour.

Next, the inside of the chamber was vacuum-replaced with a processing gas, and the processing gas was flowed at a flow rate of 25 mL / min to perform fluorination treatment. The treatment time for the fluorination treatment was 4 hours. Further, a mixed gas of fluorine (F ₂ ) gas and nitrogen gas was used as the processing gas. Further, the concentration of the fluorine gas was 20 vol% with respect to the total volume of the processing gas. After the fluorination treatment, the inside of the chamber was vacuum-replaced with nitrogen gas, allowed to cool to room temperature under a nitrogen stream (20 mL / min), and then the single-walled carbon nanotubes after the fluorination treatment were taken out from the chamber.

Next, the single-walled carbon nanotubes after the fluorination treatment were placed in an alumina container, and this container was placed in an electric tubular furnace to perform a vacuum annealing treatment. That is, the inside of the electric tubular furnace was evacuated to 1.0 × 10 ⁻⁵ Pa, and the temperature was increased to 450 ° C. at a temperature increase rate of 3.5 ° C./min under the pressure condition. After the temperature increase, a constant temperature treatment was performed at 450 ° C. for 1 hour. By this temperature increase to 450 ° C. and high temperature treatment at 450 ° C. for 1 hour, fluorine groups were detached from the single-walled carbon nanotubes to generate vacancy defects. Subsequently, the temperature was increased to 1200 ° C. at a temperature increase rate of 2.5 ° C./min under the pressure condition. After the temperature increase, a constant temperature treatment was performed at 1200 ° C. for 3 hours. By this temperature increase to 1200 ° C. and high-temperature treatment at 1200 ° C. for 3 hours, the carbon atoms in the vacancy defects generated in the single-walled carbon nanotubes were rearranged to introduce a rearranged structure. Thereafter, the inside of the electric tubular furnace was allowed to cool to room temperature, and then the inside of the chamber was replaced with nitrogen gas to produce single-walled carbon nanotubes according to this example.

(Comparative Example 1)
In this comparative example, armchair type (semiconductor type) single-walled carbon nanotubes were only subjected to vacuum annealing treatment without fluorination treatment. Other than that was carried out similarly to Example 1, and manufactured the single-walled carbon nanotube concerning this comparative example. As the single-walled carbon nanotube, one having a structure in which both ends are closed was used.

(Elemental analysis)
Elemental analysis of single-walled carbon nanotubes before treatment and single-walled carbon nanotubes according to Example 1 and Comparative Example 1 using X-ray photoelectron spectroscopy (manufactured by Thermo Fisher Scientific, trade name: K-Alpha) Went.

  (Evaluation of electrical conductivity)

<Conductivity measurement in the atmosphere>
For each of the single-walled carbon nanotubes before the treatment and the single-walled carbon nanotubes according to Example 1 and Comparative Example 1, 5 mg was put in 50 mL of ethanol and subjected to ultrasonic treatment for 15 minutes to prepare a dispersion. . Thereafter, the dispersion was filtered under reduced pressure to prepare a thin film sample having a length of 1 cm, a width of 1 cm, and a thickness of 0.5 mm.

  Then, it attached so that a gold electrode might contact | abut on the four corners of each thin film sample, and also attached the lead wire from each gold electrode to the sample holder. And the specific resistance of each thin film sample was measured by the 4-terminal method, and the electrical conductivity was calculated. The measurement was performed under conditions of atmospheric pressure, temperature of 25 ° C., and relative humidity of 35%. The measurement results are shown in Table 1 below.

<Conductivity measurement under vacuum>
Further, the conductivity of the thin film sample under reduced pressure was measured by a four-terminal method. That is, each thin film sample was attached so that the gold electrode was in contact with the four corners, and a lead wire was attached to the sample holder from each gold electrode. Then, the sample holder provided with each thin film sample was put in the chamber, respectively, and the inside of the chamber was evacuated to 1.0 × 10 ⁻⁵ Pa with a rotary pump. Thereafter, the inside of the chamber was heat-treated at 300 ° C. under reduced pressure to remove oxygen atoms adsorbed on the thin film sample. Subsequently, the inside of the chamber was cooled to room temperature under reduced pressure conditions, the specific resistance of each thin film sample was measured by a four-terminal method, and the electric conductivity was calculated. The measurement was performed under conditions of a temperature of 25 ° C. and a relative humidity of 35% under a pressure of 1.0 × 10 ⁻⁵ Pa. The measurement results are shown in Table 1 below.

(result)
As can be seen from Table 1, in the case of the single-walled carbon nanotubes before treatment and Comparative Example 1, the specific resistance under atmospheric pressure is smaller than the specific resistance under reduced pressure, and the electrical conductivity under atmospheric pressure is high. I understand that. On the other hand, in the single-walled carbon nanotube of this example, the specific resistance under atmospheric pressure is higher than the specific resistance under reduced pressure, and it is confirmed that the electrical conductivity is improved by 45% or more under reduced pressure. It was done.

Further, as a result of elemental analysis, fluorine atoms were not detected in any of the single-walled carbon nanotubes of Example 1 and Comparative Example 1 before the treatment (atomic composition percentage of fluorine atoms 0 at%). Among these, for the single-walled carbon nanotube according to Example 1, it was confirmed that the change in the value of the specific resistance under atmospheric pressure and the specific resistance under reduced pressure was not due to the presence of fluorine groups. As a result, it was shown that in the single-walled carbon nanotube of Example 1, a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, were introduced.

Claims (9)

A carbon material having a carbon six-membered ring network,
A carbon material in which a carbon five-membered ring structure and a carbon seven-membered ring structure, which are rearranged structures, are respectively incorporated in the carbon six-membered ring network. The carbon material having the carbon six-membered ring network is a carbon nanotube,
The carbon material according to claim 1, wherein the rearranged carbon five-membered ring structure and carbon seven-membered ring structure are respectively incorporated on at least side surfaces of the carbon nanotube.   The carbon material according to claim 2, wherein the carbon nanotube is a zigzag single-walled carbon nanotube, an armchair single-walled carbon nanotube, or a chiral single-walled carbon nanotube.   The carbon material according to claim 1, wherein the carbon material having the carbon six-membered ring network is graphene. A fluorination treatment step of introducing a fluorine group into the surface of the carbon material by bringing a treatment gas containing a fluorine-containing gas into contact with the carbon material having a carbon six-membered ring network;
The carbon material after the fluorination treatment step is annealed under conditions of a temperature of 400 ° C. to 1500 ° C., thereby removing the fluorine group to generate vacancies in the carbon six-membered ring structure, and rearranging the structure. A carbon material manufacturing method including an annealing treatment step for introducing a carbon five-membered ring structure and a carbon seven-membered ring structure, respectively. Using carbon nanotubes as a carbon material having the carbon six-membered ring network,
The method for producing a carbon material according to claim 5, wherein the rearrangement structure introduces a carbon five-membered ring structure and a carbon seven-membered ring structure to the side surfaces of the carbon nanotubes.   The method for producing a carbon material according to claim 6, wherein a zigzag single-walled carbon nanotube, an armchair single-walled carbon nanotube, or a chiral single-walled carbon nanotube is used as the carbon nanotube.   The method for producing a carbon material according to claim 5, wherein graphene is used as the carbon material having the carbon six-membered ring network. The electron emission material containing the carbon material of any one of Claims 1-4.

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