JP2013086993A - Nanographene and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance nanographene which is stable in its dimension, shape, structure, and purity.SOLUTION: The nanographene is obtained by using an apparatus including: a reaction vessel 1 to keep the inside in a reducing atmosphere; a metal substrate 2 as a catalyst arranged in the reaction vessel; a heater 6 to heat the metal substrate; a hydrocarbon supplying means 5 to supply a hydrocarbon into the reaction vessel; a scraping means 4 to scrape carbon fiber generated on the metal substrate by vapor phase growth; a recovery vessel 7 to recover scraped carbon fiber; a discharging means 8 to discharge the gas in the reaction vessel; and a dispersing and disassembling means to disperse and disassemble the carbon fiber in the liquid phase, includes one graphene layer or a graphene layer of overlapping two or more layers, and possesses a diameter of 1-470 nm.

Description

  The present invention relates to nanographene composed of a single graphene layer, or several to 100 layers of graphene layers, and a method for producing the same.

  As a method for producing fine carbon such as nanographite and nanographene, there is a method in which graphite, which is natural graphite, is mechanically peeled off with an adhesive tape and further peeled off with an adhesive tape. Similarly, natural graphite is treated in an acid solution to synthesize graphite oxide to swell the graphite, peel off the graphene oxide pieces by ultrasonic irradiation, centrifugation, etc., dry the collected graphene oxide pieces, and then reduce Then, there is a method of generating by removing oxygen-containing groups.

  Further, as another means, a chemical vapor deposition method (CVD such as a thermal CVD method or a microwave plasma CVD method) which is produced by making a carbon-containing gas in constant contact with a selected catalyst at a temperature of about 400 ° C. to 1200 ° C. And a graphene sheet prepared by a SiC heating method and then finely pulverized from the graphene sheet peeled off from the catalyst surface or the SiC substrate.

  However, there is a problem that it is difficult to obtain uniform nano-sized nanographene by any method and the manufacturing cost is increased.

  Nanographene is rapidly gaining importance in many industrial applications and application studies are being conducted. For example, there are hydrogen storage / adsorption / desorption, lithium storage / adsorption / desorption, catalysis, nitrogen oxide absorption / storage, etc., but the industrial realization is still poor. One reason is that nanographene that is structurally uniform cannot be mass-produced.

  If nanographene, which is highly stable in terms of size, shape, structure, purity, etc., can be mass-produced efficiently at low cost, we will supply a large amount of nanotechnology products that make use of the characteristics of nanographene at low cost. It becomes possible.

JP 2000-95509 A

  An object of the embodiment is to provide a highly functional nano graphene having high stability in size, shape, structure, and purity, and a method for producing the same.

  According to the embodiment, a reaction vessel capable of maintaining the inside in a reducing atmosphere, a metal substrate as a catalyst disposed in the reaction vessel, a heating means for heating the metal substrate, and a hydrocarbon in the reaction vessel A hydrocarbon supply means for supplying the carbon fiber, a scraping means for scraping off the carbon fibers produced on the metal substrate by vapor phase growth, a recovery container for collecting the scraped carbon fibers, and a gas in the reaction container. Nano graphene obtained by using an apparatus comprising an exhaust means for exhausting and a dispersion / disassembly means for dispersing and disassembling the carbon fiber in a liquid phase, wherein one graphene layer or a plurality of overlapping graphene layers And can have a diameter of 1 to 470 nm.

The basic block diagram of the manufacturing apparatus of the nano graphene which concerns on 1st Embodiment. In the manufacturing apparatus of FIG. 1, explanatory drawing which shows the process order to deposition of fine carbon to a metal substrate, and scraping. Schematic of the nano graphene manufacturing apparatus according to the second embodiment. The electron micrograph of the fine carbon fiber which concerns on embodiment. The electron micrograph of the fine carbon fiber which concerns on embodiment. The electron micrograph of the fine carbon fiber which concerns on embodiment. The electron micrograph of the fine carbon fiber which concerns on embodiment. The explanatory view showing the structure of the fine carbon fiber concerning an embodiment typically. The TG / DTA curve of the fine carbon fiber which concerns on embodiment. Explanatory drawing which showed typically the dismantling process which concerns on embodiment. Explanatory drawing which showed typically the dismantling process which concerns on embodiment.

Hereinafter, an apparatus for producing nanographene according to an embodiment will be described with reference to the drawings.
(First embodiment)
An apparatus for producing nanographene according to a first embodiment will be described with reference to FIGS. 1 and 2A to 2C. Here, FIG. 1 is an explanatory view showing the whole of the manufacturing apparatus, and FIGS. 2A to 2C are explanatory views showing the stacking and scraping of fine carbon fibers on a metal substrate in the order of steps.

  Reference numeral 1 in the figure indicates a reaction vessel capable of maintaining the inside in a reducing atmosphere. In the reaction vessel 1, a metal substrate (catalyst) 2 and a scraping part 4 for scraping the fine carbon fibers 3 generated on the metal substrate 2 are arranged. Connected to the reaction vessel 1 is a hydrocarbon supply means 5 for supplying hydrocarbons into the reaction vessel 1. Outside the reaction vessel 1, a heater 6 as a heating unit for heating the metal substrate 2, a recovery vessel 7 for collecting the fine carbon fibers 3, and an exhaust unit 8 for exhausting the gas in the reaction vessel 1 are arranged. . In addition, the code | symbol 9 in a figure shows the ultrasonic transducer | vibrator as a dispersion | distribution / disassembly means which applies external force to the liquid phase which is not shown in figure, and disperse | distributes the carbon fiber in a liquid phase. This ultrasonic transducer is connected to a power source (not shown).

  In the production apparatus of FIG. 1, ethanol is used as the hydrocarbon, but ethylene, propane, methane, carbon monoxide, benzene, toluene, or the like may be used. As the metal substrate 2, an iron substrate having the best compatibility with the ethanol raw material is used. However, a structural carbon steel plate made of iron and a stainless steel plate 304 may be used. Since an oxide film is usually formed on the surface of the metal substrate serving as a catalyst, the surface was activated by excluding the film. As a method of activation, surface polishing and acid treatment were performed.

Next, the operation of the manufacturing apparatus will be described with reference to FIGS. 1 and 2A to 2C.
2A, the temperature of the reaction vessel 1 was adjusted to 600 ° C. to 750 ° C., preferably 670 ° C., and ethanol was preheated at 350 ° C. and injected into the reaction vessel 1. The raw material ethanol is thermally decomposed into gas in the reaction vessel 1, and carbon atoms are taken into the metal substrate 2. Next, when the carbon in the metal substrate 2 is saturated, it is considered that the carbon precipitates from the metal substrate 2 and grows in a crystal form. The fine carbon fiber 3 produced in the crystal form (see FIG. 2B).

  Next, the fine carbon fiber 3 produced over several tens of minutes on the metal substrate 2 was scraped off by a scraping part 4 as shown in FIG. 2C and recovered in a recovery container 7 outside the reaction container. The scraping was scraped off so as to remain on the metal substrate 2 with a thickness of about 0 to 5 mm, and the fine carbon fiber 3 grown again was scraped off and repeated. Thus, the production | generation and scraping of the fine carbon fiber 3 are performed repeatedly. Even if there are fine carbon fibers left on the metal substrate 2, since the hydrocarbons are sufficiently supplied to the metal substrate 2, the amount of fine carbon fibers produced can be kept constant for a long time.

(Second Embodiment)
An apparatus for producing nanographene according to a second embodiment will be described with reference to FIG. However, the same members as those in FIG. 1 and FIG.
Reference numeral 11 in the drawing denotes a cylindrical vertical reaction vessel that can keep the inside in a reducing atmosphere and can be blocked from the outside air. Inside the reaction vessel 11, a cylindrical metal substrate (catalyst) 12 that is coaxial with the reaction vessel 11 is arranged. The reaction vessel 11 is provided with a scraping mechanism for scraping the fine carbon fibers 3 generated on the surface of the metal substrate 12. Here, the scraping mechanism is composed of a driving device 13, a main shaft 14 that is pivotally supported by the driving device 13 in the direction of arrow A, and a helical scraping blade 15 attached to the main shaft 14. Has been. The reaction vessel 11 is connected to an inert gas supply means 16 for supplying an inert gas into the reaction vessel. 2 indicates a seal member disposed around the main shaft 14 in the upper part of the reaction vessel 11. In addition, the hydrocarbon, the material of a metal substrate, etc. in the manufacturing apparatus of FIG. 3 are the same as those of FIG. However, since the metal substrate 12 serving as a catalyst is thinned during the carbon fiber generation process, it has a structure that can be replaced with a new substrate after a certain period of time.

Next, the operation of the manufacturing apparatus of FIG. 3 will be described.
First, the temperature of the reaction vessel 11 was adjusted to 600 ° C. to 750 ° C., preferably 670 ° C., and ethanol was preheated to 350 ° C. and injected into the reaction vessel 11. The raw material ethanol is thermally decomposed into gas in the furnace, and carbon atoms are taken into the metal substrate 12. Next, it is considered that when the carbon in the metal substrate 12 becomes saturated, the carbon precipitates from the metal substrate 12 and grows in a crystal form. The fine carbon fibers 3 are formed and grown in the form of crystals.

  Next, the fine carbon fiber 3 grown over several tens of minutes on the metal substrate 12 was scraped off with the blade 15 and recovered in the recovery container 7 outside the reaction container. In the scraping, the distance between the metal substrate 12 and the tip of the scraping blade 15 is adjusted so as to remain on the metal substrate 12 with a thickness of about 0 to 5 mm. Here, the spiral scraping blade 15 rotates continuously in the direction of arrow A at a speed of 0.01 to 0.05 rpm by the driving device 13 or is scraped intermittently every 20 to 60 minutes. To do. As a result, the fine carbon fiber 3 is scraped off, and then the fine carbon fiber 3 grown again is scraped again, and continuous production can be continued. Even if there are fine carbon fibers left behind, the amount of fine carbon fibers produced can be kept constant for a long time because the hydrocarbon is sufficiently supplied to the metal substrate.

As mentioned above, although the manufacturing apparatus and manufacturing method of the fine carbon fiber have been described, the size, shape, structure, and purity of the generated fine carbon fiber will be described.
FIG. 4 is an electron micrograph of fine carbon fibers. In FIG. 4, carbon fibers appear to be intertwined in a fibrous form. FIG. 5 is an electron micrograph of carbon fiber having a diameter of 100 to 300 nm, which is an enlarged view of FIG. FIGS. 6A and 6B are transmission electron micrographs. From FIG. 6A, it can be seen that carbon fibers are growing on both sides of the catalyst fine particles. FIG. 6B is an enlarged view of a portion B in FIG. 6A, and it can be seen from FIG. 6B that the fine carbon fiber has a structure in which crystallized graphene pieces are stacked. Further, FIGS. 7A and 7B show a carbon structure at a position slightly separated from the catalyst particles in a transmission electron micrograph of fine carbon fibers. The portion surrounded by the square (□) in FIG. 7A is enlarged to C and D portions, and the enlarged view of the D portion in FIG. 7B shows the approximate orientation of graphene with white streaks.

  From this, it turned out that the fine carbon fiber manufactured with the apparatus of this embodiment is a linear graphite nanocarbon fiber (GNF) having a diameter of 100 to 300 nm in which krafen is laminated in multiple layers in the longitudinal direction. Further analysis shows that the distance between the graphenes is 0.3 to 0.4 nm, the graphenes overlap to form crystallites having an average crystal thickness of 3 to 10 nm, and the crystallites overlap in multiple layers to form a linear shape with a diameter of 100 to 300 nm. It turns out that it constitutes GNF.

  8A to 8D are diagrams schematically showing the structure. 8A is a cross section of the GNF 21, FIG. 8B is a cross section of the graphene lump (crystallite) 22, FIG. 8C is a cross section of the graphene dispersion piece 23, and FIG. 8D is a graphene. 24 is shown.

Table 1 below shows the distribution of the four samples by measuring the diameter of the fine carbon fibers. From Table 1, it can be seen that the thickness is distributed in the range of 100 to 300 nm in diameter. Moreover, it can be seen from Table 1 that the average diameter is 151.5 to 198.9 nm, with about 150 to 200 nm being the largest diameter. Including other data, the diameter is 80 to 470 nm, preferably 130 to 300 nm.

  FIG. 9 is a graph showing the relationship between the temperature and temperature difference of the fine carbon fiber (sample 1 (n = 2) in Table 2 below) obtained by the above embodiment, differentiation of the temperature difference (time change), and weight change. FIG. The temperature is data up to 1000 ° C. In FIG. 9, (a) is a curve showing the weight change (TG) of the fine carbon fiber during heating, (b) is a curve showing the temperature difference (DTA) between the sample and the reference material during heating, and (c) is the differential. It is a curve which shows the change (DDTA) with respect to the time of the temperature difference detected with a thermocouple. From FIG. 9, it can be seen that the thermal decomposition starting temperature (heat-resistant temperature) is 616 ° C., and the weight reduction rate is 94.1% at 1000 ° C.

Table 2 shows the results of measuring four samples by this method. From Table 2, the thermal decomposition start temperature (heat resistant temperature) is distributed from 540 ° C. to 616 ° C. In addition, when other data is included, the heat-resistant temperature is 530 to 630 ° C, preferably 540 to 620 ° C. Furthermore, from Table 2, the weight reduction rate (purity) was approximately 94% or more. Moreover, when other data were included, it was 90 to 97%, and preferably 94 to 97%. The residue is a component that does not burn at 1000 ° C., and for example, a catalyst is assumed.

In addition, since the manufacturing apparatus which concerns on the said embodiment grows a carbon fiber on a board | substrate, since a catalyst metal transfers only a necessary minimum to the carbon fiber side, purity becomes very high. Moreover, since continuous production | generation is possible, mass production can be implement | achieved and industrial spread can be enabled.
In the above, the manufacturing method of the fine carbon fiber and the size, shape, structure, and purity of the produced fine carbon fiber have been described. Next, a method for producing nano graphene in which fine carbon fibers are dispersed and disassembled will be described.

FIGS. 10A to 10E are explanatory views schematically showing a dispersion and disassembly process of fine carbon fibers.
FIG. 10A shows a state where innumerable fiber-shaped GNFs 21 that have been generated from the generation furnace are intertwined and aggregated. FIG. 10B shows a state in which the entangled GNF 21 of FIG. FIG. 10C shows an enlarged schematic diagram of one GNF (X portion in FIG. 10B) generated by the manufacturing apparatus. FIG. 10D shows nanographene (several layers to 100 layers are stacked) obtained by slicing and disassembling the GNF 21 of FIG. FIG. 10E illustrates nanographene obtained by further disassembling the stacked nanographene of FIG. 10D to form a single layer. FIG. 10F illustrates the nanographene of FIG. 10E viewed from above. When an appropriate amount of the fine carbon fiber is added to a resin, paint, metal, etc., it can be expected to improve properties such as conductivity and mechanical strength. It cannot be pulled out sufficiently.

  The deposited graphene constituting the fine carbon fiber is strongly bonded by SP2 covalent bond in the lateral six-membered ring plane, but it is not a covalent bond between the graphene layers and is a molecule having a weaker binding force than that. They are connected by force. When the fibrous GNF is further unwound from the state where the fibrous GNF has been released, or when some other treatment is applied, the intermolecular force between the graphene layers is cut off, and the nano graphene in which several to 100 layers are deposited (FIG. 10D) However, nanographene with one layer of graphene (FIG. 10E) is generated.

  FIGS. 11A to 11E are explanatory views schematically illustrating a dispersion and disassembling process in a case where metal fine particles derived from a catalyst remain in fine carbon fibers. FIG. 11 (A) shows a state where innumerable fiber-shaped GNFs 21 that are generated after coming out of the generating furnace are intertwined and aggregated. FIG. 11B shows a state in which the aggregated GNF 21 of FIG. FIG. 11 (C) shows an enlarged schematic view of one GNF (X part in FIG. 11 (B)) generated by the manufacturing apparatus, and reference numeral 25 shows catalyst-derived metal fine particles. FIG. 11D illustrates nanographene obtained by slicing and disassembling the GNF 21 of FIG. Here, the metal fine particles 25 are removed by dissolution, natural sedimentation, centrifugation, magnetic force or the like. FIG. 11E illustrates nanographene obtained by further disassembling the stacked nanographene of FIG. 11D to form a single layer. The metal fine particles 25 are dissolved in an acidic solution, or separated and removed by a method using gravity such as natural sedimentation or centrifugation, or an electromagnetic means such as magnetic separation, and carbon of nano graphene obtained by disassembly. Purity can be increased. Thereby, functions, such as an electrical property of nano graphene, can be improved.

Here, a specific embodiment in which the generated fine carbon fiber is dispersed and disassembled will be described.
(Third embodiment)
As described above, the generated GNF has a diameter of 80 to 470 nm, and graphene pieces are laminated to form fine carbon fibers. Fine carbon fiber aggregates intertwined with GNF were mixed with nitric acid (HNO ₃ ) (2 mol / L), sulfuric acid (H ₂ SO ₄ ) (5 mol / L), and potassium permanganate (KMnO ₄ ) (0.15 mol / L). 5% by weight is added to the mixed aqueous solution of L).

  When this is agitated with a stirrer for 24 hours, the entangled GNFs are dissolved, and oxygen-containing groups such as epoxy groups, hydroxyl groups, carboxyl groups, etc. are randomly selected at the carbons constituting the fine carbon fiber. A (chemically modified group) is added, and a graphene oxide laminate in which the graphene layer is enlarged and hydrophilized is obtained. At this point, the catalyst metal particles that existed between the graphene layers diffuse into the mixed solution and are simultaneously dissolved by the acid, so that they can be removed. When this graphene oxide laminate is dispersed in water and irradiated with ultrasonic waves, water molecules permeate between the graphene layers, and the exfoliation of the graphene layer proceeds, so that exfoliated graphene oxide can be obtained. In addition, you may stir instead of ultrasonic irradiation.

  The aqueous solution in which graphene oxide is dispersed is heated to remove moisture to obtain graphene oxide powder, and then heated at 300 to 1000 ° C. in an inert gas atmosphere such as argon. The π-electron conjugated system recovers and fine carbon with graphene laminated is generated.

(Fourth embodiment)
The fourth embodiment shows an example of disassembling GNF.
In this embodiment, water is selected as a dispersion and demolition solvent, and since it has a polar site, it is compatible with water and has good compatibility with low-polar fine carbon fibers (non-ionic interface). mixing _{CH 3 O- (C 2 H 5} OC 2 H 5 O) n-CH 3, C 2 H 5 O- (C 2 H 5 OC 2 H 5 O) n-C 2 H 5 is active agents) The liquid was selected as a dispersant. Here, n in the above molecular formula indicates that n number of “()” structures are continued, and is a liquid dispersant having an average molecular weight of about 1000 to tens of thousands.

  5% by weight of fine carbon fiber aggregates and 5% by weight of the mixed dispersant having the above structure were added to water, and the mixture was gently stirred for 2 hours while heating to 50 to 60 ° C. to prepare a fine carbon dispersion. The fine carbon fibers that were entangled and aggregated were dispersed, and the graphene laminate constituting the fine carbon fibers was disassembled.

By disassembling the nano graphene laminate, the catalyst fine particles existing between the graphene layers are dispersed and released in the dispersion.
As a means for separating catalyst fine particles, metal fine particles and nanographene were separated by a specific gravity difference at a high-speed centrifugal separation of 70000 rpm, and the supernatant from which the catalyst particles were removed was collected to obtain a nanographene dispersion.

  When the average particle diameter of the nano graphene in the nano graphene dispersion liquid disassembled by the above means was measured with a laser scattering particle size distribution analyzer, the 50% cumulative volume particle diameter D50 was about 200 nm. When observed with an electron microscope, nanographene was in the form of particles, and it was confirmed that the graphene was stacked in multiple layers.

  In the fourth embodiment, as the surfactant, in addition to the nonionic surfactant, a cationic surfactant, an anionic surfactant, a zwitterionic surfactant, or a plurality of these components is used. Can be used.

  In addition, when a nonionic surfactant is used, the fine carbon fiber and the surfactant molecule are adsorbed by electrostatic attraction with the micropolar part of the surfactant molecule composed of a carbon chain or a carbon ring. The fine carbon entangled by electrostatic attraction and repulsion between polar sites of the surfactant molecule is peeled off, and the laminated graphene is disassembled. On the other hand, when an ionic surfactant is used, fine carbon and a surfactant molecule are adsorbed by electrostatic attraction with a nonionic site of a surfactant molecule composed of a carbon chain or a carbon ring, Fine carbon fibers entangled by electrical attraction and repulsion between ionic sites of the surfactant molecule are peeled apart, and the laminated graphene is disassembled.

  Nano graphene with one layer of graphene or a few layers to 100 layers produced in the above embodiment is an electronic component using high photoelectron mobility, a chemical sensor or hydrogen using chemical sensitivity or chemical reaction New application fields such as storage materials, mechanical sensors using high mechanical strength, laser members and transparent electrodes using light transmission and conductivity, and wiring materials using high current density resistance can be expected.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,11 ... Reaction container, 2,12 ... Metal substrate (catalyst), 3 ... Fine carbon fiber, 4 ... Scraping part, 5 ... Carbon raw material supply means, 6 ... Heater, 7 ... Collection container, 8 ... Exhaust means, DESCRIPTION OF SYMBOLS 9 ... Ultrasonic vibrator, 13 ... Drive apparatus, 15 ... Scraping blade, 21 ... Graphite nanocarbon fiber (GNF), 22 ... Graphene lump, 23 ... Graphene dispersion piece, 24 ... Graphene, 25 ... Metal fine particle.

Claims (7)

  A reaction vessel capable of maintaining the inside in a reducing atmosphere, a metal substrate as a catalyst disposed in the reaction vessel, a heating means for heating the metal substrate, and a hydrocarbon supply for supplying hydrocarbons into the reaction vessel Means, scraping means for scraping off the carbon fibers generated on the metal substrate by vapor phase growth, a recovery container for collecting the scraped carbon fibers, and exhaust means for exhausting the gas in the reaction container; Nanographene obtained using an apparatus equipped with a dispersion / disassembly means for dispersing and disassembling the carbon fiber in a liquid phase, comprising one graphene layer or a plurality of overlapping graphene layers, 1 to 470 nm Nanographene characterized by having a diameter of   A cylindrical reaction vessel capable of maintaining the inside in a reducing atmosphere, a cylindrical metal substrate serving as a catalyst disposed coaxially with the reaction vessel in the reaction vessel, and heating means for heating the metal substrate; , Hydrocarbon supply means for supplying hydrocarbons into the reaction vessel, inert gas supply means for supplying an inert gas into the reaction vessel, and carbon produced on the inner wall of the metal substrate by vapor phase growth Scraping means having a spiral scraping blade for scraping the fibers, a recovery container for collecting the scraped carbon fibers, an exhaust means for exhausting the gas in the reaction container, and dispersing the carbon fibers in the liquid phase Nanographene obtained by using an apparatus equipped with a dispersion / disassembly means for disassembling and comprising one graphene layer or a plurality of overlapping graphene layers, and having a diameter of 1 to 470 nm. Nanographene to.   The dispersing / disassembling means includes means for oxidizing the carbon fiber in an acidic solution and substituting or adding a chemical modification group containing oxygen to carbon to increase the distance between graphenes, and dismantling to a graphene laminate; 3. The nano graphene according to claim 1, comprising means for recovering the π-electron conjugated system by removing a chemical modification group substituted or added to carbon from the graphene laminate. The dispersion / disassembly means is:
A mixing means for mixing the carbon fiber and the ionic surfactant in a liquid phase;
The surfactant molecule composed of the carbon fiber and the carbon chain or the carbon ring is adsorbed by electrostatic attraction with the nonionic part of the surfactant molecule, and the electric charge between the ionic parts of the surfactant molecule The nano graphene according to claim 1 or 2, further comprising means for peeling carbon fibers entangled by mechanical attraction and repulsion, and further disassembling the laminated graphene. The dispersion / disassembly means is:
A mixing means for mixing the carbon fiber and the nonionic surfactant in a liquid phase;
An action of adsorbing the carbon fiber and the surfactant molecule by an electrostatic attractive force with a non-polar site composed of a carbon chain or a carbon ring of the surfactant molecule, and an electrostatic attractive force between the polar sites of the surfactant molecule The nano graphene according to claim 1 or 2, further comprising means for peeling carbon fibers entangled by repulsive force and disassembling the laminated graphene.   6. The apparatus according to claim 1, further comprising means for separating and removing residual metal particles in the dispersion liquid used as a catalyst and remaining in the carbon fiber after disassembling the dispersed carbon fiber. Nanographene according to any one of the above.   A reaction vessel capable of maintaining the inside in a reducing atmosphere, a metal substrate as a catalyst disposed in the reaction vessel, a heating means for heating the metal substrate, and a hydrocarbon supply for supplying hydrocarbons into the reaction vessel Means, scraping means for scraping off the carbon fibers generated on the metal substrate by vapor phase growth, a recovery container for collecting the scraped carbon fibers, and exhaust means for exhausting the gas in the reaction container; Using a device equipped with dispersion / disassembly means for dispersing and disassembling the carbon fibers in a liquid phase, the carbon fibers are composed of overlapping multilayer graphene layers, from carbon fibers having a diameter of 80 to 470 nm, A method for producing nanographene, comprising producing nanographene having a diameter of 1 to 470 nm, comprising a plurality of overlapping graphene layers.

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