JP2003054901A - Core-shell carbon nanofiber for hydrogen storage and process for preparing the fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core-shell nanostructure that are capable of providing hydrogen storage in an economical, safe, light weight and simple manner. SOLUTION: This core-shell nanostructure 1 each includes a slit-pore nanofiber 2 that encapsulates a hydrogen storage substance 6. The core-shell nanostructure has an increased hydrogen storage capacity because hydrogen is stored in the slit-pore carbon nanofiber itself, as well in a hydrogen storage substance contained within the nanofiber. Further the kinetics of hydrogen adsorption/desorption are improved because the hydrogen storage substance is present in nanometer sized particles and is prevented from being oxidized by the nanofiber through which oxygen can not pass. Also arc-discharge and arc-CVD method is used for producing the core-shell nanostructures.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION a. TECHNICAL FIELD OF THE INVENTION The present invention relates generally to carbon nanostructures, and more particularly to methods of use in hydrogen storage.

[0002]

2. Description of the Related Art b. Related Art Some metals and alloys-for example, by forming hydrides-can store hydrogen in a reversible manner and thus have inherent stability for various applications. However, known alloys capable of occluding hydrogen in a reversible manner have not been widely used on a large scale due to some difficulties. In fabrication and in addition to the challenge of limited hydrogen storage capacity, one drawback is that the alloy forms oxides on its surface when it comes into contact with ambient air. Therefore, these known alloys must be activated at high pressure or high temperature each time they are exposed to air. Moreover, during the adsorption / desorption cycle, these known alloys are usually crushed into fine particles, reducing their structural integrity. This loss of structural integrity results in reduced kinetics in the hydrogen adsorption / desorption process. To improve the kinetics of hydrogen adsorption / desorption-the rate at which hydrogen is adsorbed and released-the researchers have energetically studied nanometer-sized metals and alloys as new and more efficient hydrogen storage materials. I am studying.

US Pat. No. 5,763,363 to Schulz et al. Is one example of a nanometer sized material used for hydrogen storage. However, the stability of these nanometer-sized metals and alloys in air is a problem for all practical applications. That is, even if the dynamics of this process
Even if these metals and alloys are significantly improved by milling them into nanometer-sized particles, the oxidative stability of these particles remains a major barrier for all practical applications.

In general, carbon coatings can prevent metals or alloys (including nanometer-sized materials) from oxidizing. However, this carbon coating is in the form of single-walled nanotubes (SWNTs), multi-walled nanotubes (MWNTs), one or more graphite layers concentrically surrounding the hydrogen storage material, or amorphous carbon. Therefore, for hydrogen storage, such coatings
It is common to largely or completely prevent hydrogen from entering or leaving a metal or alloy.

On the other hand, the carbon material itself, especially SW
Hydrogen storage in NT and carbon nanofibers has recently received much attention.

Some researchers believe that the hydrogen storage capacity of the purified SWNTs themselves can reach up to 5-10% by weight under optimal conditions. For example, "Hydrogen Adsorption In
Carbon Materials ”, MS Dre
Sselhaus et al., MRS Bulletin, 19
November 1999, pp. 45-50; "Storage o.
f Hydrogenin Single-walled
Carbon Nanotubes ", AC Dil
Lon et al., Nature, March 1997, Volume 386,
377-379; "Hydrogen Storage.
e in Single-walled Carbon N
anotubes at Room Temperatur
Re ", C. Liu et al., Science, 1999, 1
January, 286, 1127-1129; and "Hyd.
rogen Adsorption and Cohes
Ive Energy of Single-Wall
d Carbon Nanotubes ", Y. Ye et al.,
Appl. Phys. Lett. , April 1999, 7
4, page 2307-2309.

However, in order to practically use SWNTs for storing hydrogen, the SWNs are large-scale and low-cost.
Further technology for the production and purification of T has to be developed. In general, it is cost prohibitive to use the SWNTs themselves, such as the current US $ 1,000 / gram price for hydrogen storage.

With regard to carbon nanofibers, there has been intense debate regarding the hydrogen storage capacity.
The amount of hydrogen occluded in the carbon nanofiber itself was measured.
It varied up to wt%. For example, "Hydrogen S
transfer in Graphite Nanofib
ers ", A. Chambers et al., J. Phys. C.
hem. B. , 1998, 102, 4253;
"Further Studies of the Int
erase of Hydrogen with G
Raphite Nanofibers ", C. Par
K., et al. Phys. Chem. B. , 1999, 1
03, 10572-10581; and "Hydro.
gen Desorption and Adsorbt
Ion measurements on Graphi
te Nanofibers ", C. Ahn et al., App
l. Phys. Lett. , 1998, 73, 33
See pages 78-3380. Furthermore, even within the research group, the measured amount of hydrogen storage varies greatly.

Rodriguez et al. (Rodrigue
US Pat. No. 5,653,951 to Z) et al. discloses storing hydrogen in layered nanostructures, including nanofibers. Also, Rodrig
Uez discloses that a metal capable of dissociatively storing hydrogen can be incorporated into the voids of the nanostructure, that is, the hollow inner core. However, Ro
driguez is a small amount of such metal -1 to 5
Only weight% and less than 1% by volume are considered. Therefore, Rodriguez relies mostly on the nanostructure itself for the major hydrogen storage media.
However, as mentioned above, the measured amount of hydrogen storage by these nanostructures itself fluctuates greatly, and therefore a reliable hydrogen storage medium cannot be provided.

[0010]

Problems to be Solved by the Invention c. PROBLEMS SOLVED BY THE INVENTION One object of the present invention is to overcome the known drawbacks of the method of storing liquid, compressed gas and by-product hydrogen of a reformer. More particularly, it is to provide an economical, safe, lightweight and simple hydrogen storage medium for transportation and portable hydrogen fuel cell devices.

Another object of the present invention is to solve the problems of the related art. More specifically, the carbon shell (carbon s) is used so that the hydrogen transfer to the hydrogen storage material is not hindered and the hydrogen storage material is not oxidized.
hydrogen storage material enclosed in the
It is one of the objects of the present invention to provide a hydrogen storage medium containing-such as a metal or an alloy which produces a hydride.
If such an arrangement is adopted, a large amount of hydrogen storage material is contained, and it is responsible for most of the hydrogen storage capacity of the hydrogen storage medium.

A further object of the present invention is to develop an enhanced hydrogen storage capacity by using a core-shell type nanostructure, in which case the core-shell type nanostructure contains hydrogen. It is capable of occluding and comprises slit-shaped pore type carbon nanofibers having a central hole, in which metal, alloy or other hydrogen occluding substance is arranged for further occluding hydrogen. As used herein, carbon nanofibers
It is a nanofiber in which the graphite surface extends obliquely with respect to the central axis of the carbon nanofiber to provide an open planar end portion on the outer edge of the carbon nanofiber. Such a slit-shaped pore type carbon nanofiber structure is different from a carbon nanotube. On the other hand, in this carbon nanotube, the graphite surface extends in a direction substantially parallel to the central axis of the carbon nanotube. There are no open planar ends at the outer edges of the (although there may be open planar ends at the ends of the nanotube itself).

[0013]

[Means for Solving the Problems] d. Means for Solving the Problems According to one aspect of the present invention, a core-shell type nanostructure is provided. The core-shell type nanostructure comprises-a slit-like pore type carbon nanofiber surrounding a hydrogen storage material, including for example a metal or an alloy. Core-shell nanostructures provide an excellent solution for the purpose of preventing oxidation of hydrogen storage materials, yet allow this material to interact with hydrogen. More specifically, this slit-shaped pore type carbon nanofiber has a lattice spacing of 0.35 nm-that is, a distance between parallel graphite planes-allowing the permeation of hydrogen molecules (having a dimension of 0.29 nm). However, on the other hand, oxygen molecules (0.45
(with dimensions of nm). Furthermore, the slit-shaped carbon nanofibers themselves provide additional hydrogen adsorption sites.

In addition, the present invention achieves the above and other objects by providing a hydrogen storage composition consisting of the following: graphite planes arranged parallel to each other around a central hole, the graphite A slit-shaped pore type carbon nanofiber in which hydrogen is occluded between the surfaces; and a hydrogen occluding substance arranged in the central hole,
The hydrogen storage material is 10 to 90% by volume of the constituent.
To be.

The present invention further achieves these and other objectives by providing a hydrogen storage composition comprising: a graphite surface disposed parallel to each other around a central hole, the graphite A slit-shaped pore type carbon nanofiber in which hydrogen is occluded between the surfaces; and a hydrogen occluding substance arranged in the central hole portion, wherein the hydrogen occluding substance is measured by volume% to obtain the graphite Have a hydrogen storage capacity that is superior to that of the surface.

In addition, the present invention achieves the above and other objects by providing a method for producing a core-shell type nanostructure, which comprises: a bowl-type graphite cathode, a carbon anode, and a catalyst. Wherein the catalyst comprises: Li, Ni, Mg, A
l, Ti, V, Nb, Ga, In, Fe, Co, Ni,
Cu, Zn, Ge, Pb, Mo, Sn, B, C, Ir,
Rh, Ru, Pt, Se, Sc, Y, La, Ce, P
r, Nd, Gd, Mi-La, Mg-Ni, Mg-C
e, Ca-Ni, Na-Al, Ni-Ce, or Ti-
Fe-C, wherein the catalyst is 10 times the amount of carbon-containing material in the anode and in the catalyst.
To 90 wt.%; And in the presence of the catalyst, generating an arc discharge between the cathode and the anode to produce a core-shell nanostructure on the cathode. .

Still further, the present invention achieves the above and other objects by providing a method for producing a core-shell type nanostructure, which comprises: a bowl-type graphite anode, a carbon cathode, Raw material gas,
And a catalyst, said catalyst comprising: L
i, Ni, Mg, Al, Ti, V, Nb, Ga, In,
Fe, Co, Ni, Cu, Zn, Ge, Pb, Mo, S
n, B, C, Ir, Rh, Ru, Pt, Se, Sc,
Y, La, Ce, Pr, Nd, Gd, Mi-La, Mg
-Ni, Mg-Ce, Ca-Ni, Na-Al, Ni-
Ce or Ti-Fe-C; and in the presence of the source gas and the catalyst, an arc discharge is generated between the cathode and the anode to form a core-shell type nano-particle on the anode. Creating a structure.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The above and other objects and advantages of the present invention will be apparent from the detailed description of the preferred exemplary embodiments of the present invention with reference to the accompanying drawings. , And the same reference numbers represent the same or corresponding parts throughout all of the several drawings.

E. BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention relate to a core-shell type nanostructure 1 capable of exhibiting hydrogen absorption in an economical, safe, lightweight and simple manner. In order to express hydrogen storage, a substance 6 capable of reversibly storing hydrogen is arranged inside the slit-shaped pore type carbon nanofiber 2. Furthermore, since hydrogen can be stored in the nanotube 2 itself, the total hydrogen storage capacity of the core-shell type nanostructure 1 is increased. In that case, the hydrogen storage medium can be formed from these core-shell type nanostructures 1.

As shown in FIGS. 1 to 4, the core-shell type nanostructure 1 is disposed inside the slit-shaped pore type carbon nanofiber 2 and the central hole of the slit-shaped pore type carbon nanofiber 2. Substance 6-capable of reversibly occluding hydrogen. High resolution transmission electron microscope (TEM) of core-shell type nanostructure according to the present invention
See also photographs 5A and 5B, FIG. 5B.
FIG. 5B is an enlarged view of FIG. 5A.

Returning to FIGS. 1 through 4, the slit-shaped pore type carbon nanofiber 2 is hollow and generally includes a graphite surface 4 extending obliquely with respect to the central axis of the nanotube 2. Graphite surface 4 is 0.35
Slit-shaped pore type carbon nanofibers 2 are stacked in parallel with each other at a lattice spacing 12 of nm so that their flat ends are the outer edges of the core-shell type nanostructure 1.
Are stacked in the direction along the length of the. Since the lattice spacing, that is, the distance between the graphite surfaces 4, is 0.35 nm,
The nanofibers 2 allow hydrogen (having a dimension of 0.29 nm) to pass between these graphite faces. Furthermore, since hydrogen can pass between the graphite surfaces 4, hydrogen can also be occluded between them. However, oxygen (having a dimension of 0.45 nm) cannot pass between the graphite faces 4, thus
The nanofibers 2 prevent the hydrogen storage substance 6 from oxidizing. Figure 4
As can be seen, each graphite surface is in the shape of a hollow frustum. However, the shape of the graphite surface 4 is not important. That is, as shown, the slit-shaped pore-shaped carbon nanofibers 2 may have a circular cross section or any other desired shape, such as quasi-quadrangle, ellipse, polyhedron, etc. The graphite surfaces 4 can be arranged. Furthermore, graphite surface 4
The slit-shaped pore type carbon nanofibers 2 have a crystallinity of 1 to 100% as long as the ability to prevent the oxidation of the entrapped hydrogen storage material 6 is maintained while the ability to permeate hydrogen is maintained. The graphite surfaces 4 are arranged so as to have. However, the higher the crystallinity, the more favorable the kinetics. That is, the higher the crystallinity, the easier hydrogen will pass through the slit-shaped pore type carbon nanofiber 2.

Cross-sectional area surrounded by slit-shaped pore-type carbon nanofibers 2—that is, the area based on the outermost edge of the graphite surface 4, or the cross-section outside the structure as shown in either FIG. 2 or 3. inside of the total area of the outer edge portion - is in the range of 25 nm ² to 250,000Nm ^2, preferably is to 100 nm ² is not in the range of 10,000nm ^2. The central hole of the slit-shaped pore type carbon nanofiber 2 is 1 nm ² to 100,000.
Has a cross-sectional area of 0 nm ² , 10 nm ² to 8,
It is preferably in the range of 000 nm ² . These cross-sectional areas are not important, but for maintaining the hydrogen storage capacity, the kinetics of hydrogen transfer through the hydrogen storage material 6 in the central hole, and the stability in the slit-shaped pore-shaped carbon nanofibers 2. It is not only sufficient strength, but also a balance with considerations including ease of production and efficiency. For example, regarding the hydrogen storage, when the area of the central hole is less than 10 nm ² , the maximum hydrogen storage capacity becomes small, but the kinetics are excellent. On the other hand, the area of the central hole is 8,000
Above 0 nm ² , the kinetics of hydrogen transfer through the hydrogen storage substance 6 decreases.

The length of the slit-shaped pore type carbon nanofiber 2 varies, but is generally 100 nm to 100 nm.
between μm. It is difficult to prepare nanofibers 2 having a length of less than 100 nm, and the oxidized hydrogen storage material 6 is used.
Due to the higher ratio of (ie, the oxide layer 8) to the hydrogen storage substance 6 available for hydrogen storage, the core-shell type nanostructure becomes a useless hydrogen storage medium. That is, since the carbon nanofibers 2 are hollow and open-ended, the oxide layer 8 is formed on the hydrogen storage material 6 exposed at each open end. In the oxide layer 8, hydrogen is a hydrogen storage material 6
Avoid being occluded on that part of the. Therefore, as the ratio of the amount of the oxide layer 8 to the amount of the hydrogen storage substance 6 increases, the hydrogen storage efficiency decreases, that is, the storage amount of the constituent made of the core-shell type nanostructure 1 increases. The volume% of hydrogen taken up may be low.

The hydrogen storage substance 6 may be any substance as long as it can store hydrogen reversibly. Preferably, a metal or alloy capable of forming a hydride is used. Examples of suitable metals include Li, Na, Mg, Al, Ti, V, Nb,
Ga, In, Fe, Co, Ni, Cu, Zn, Ge, P
b, Mo, Sn, B, C, Ir, Hr, Ru, Pt, S
Examples thereof include e, Sc, Y, La, Ce, Pr, Nd, and Gd. Preferred metals are Li, Mg, Al, Ca,
Zr and Ni. Examples of suitable alloys include: Ni and La; Mg and Ni; Mg and Ce; C.
a and Ni; Na and Al; Ni and Ce; and Ti and Fe
And C. It is preferable to use a substance having an excellent hydrogen storage capacity when measured at room temperature and 1 atm. It is more preferable to use a substance having a capacity superior to the hydrogen storage capacity of the slit-shaped pore type carbon nanofiber 2. That is, it is preferable to use the hydrogen storage substance 6 rather than the carbon nanofibers 2 as the important hydrogen storage medium.

As shown in FIGS. 1 and 3, the hydrogen storage material 6
Are arranged in the central hole of the slit-shaped pore type carbon nanofiber 2. In addition, the hydrogen storage material 6 may be continuously arranged in the central hole of the slit-shaped carbon nanofibers 2 up to both ends, or as shown in FIG. May be arranged. However, since this material expands as the hydrogen storage material absorbs hydrogen, it is preferable that the core-shell type nanostructure 1 contains at least some voids 10. Therefore, if there are no voids, this substance 6 becomes more likely to damage the slit-shaped pore type carbon nanofiber 2 as the hydrogen storage substance 6 absorbs hydrogen. Furthermore, these voids can store hydrogen.

Further, the hydrogen storage material 6 can have a structure ranging from amorphous to crystalline, but when it is contained inside the nanofibers 2, the crystal structure is the most stable in nanometer size, so that it is crystalline. The structure is preferred. Furthermore, the crystalline structure contributes to a better kinematics with regard to the movement of hydrogen through it.

Further, the amount of the hydrogen storage material 6 in the core-shell type nanostructure is 10 to 90% by volume. The amount of hydrogen storage substance 6 in the core-shell type nanostructure is
It is preferably 30 to 70% by volume. The amount of the hydrogen storage material 6 depends on the hydrogen storage capacity, the kinetics of movement of hydrogen through the hydrogen storage material 6 inside the central hole, and the stability in the slit-shaped pore-shaped carbon nanofibers 2. Not only sufficient strength but also easiness and efficiency in production-as in the case of the area of the central hole of the carbon nanofiber 2-depends on the balance with various considerations.

The core-shell type nanostructure 1 of the present invention is
It can be synthesized by using an arc discharge method or by, for example, a high temperature arc chemical vapor deposition (CVD) method. With either method, H.264. Huang
The name of the invention such as "Arc Electrodes for
Synthesis of Carbon Nanost
disclosed in Japanese Patent No. 2000-375044 (hereinafter referred to as Japanese Patent Application No. '044), the entire disclosure of which is incorporated herein by reference. In the discussion below, only one carbon-containing electrode is used with a bowl-shaped graphite electrode for simplicity of understanding. It is possible and preferred to use more than one such carbon-containing electrode as described in '044. In addition, the core-shell nanostructures of the present invention are made. The parameters for performing the arc discharge and arc CVD method for the same SW as described in Japanese patent application '044.
It is similar to the parameters used in the NT fabrication method. However, the collection position of the desired carbon structure is different. That is, the core-shell nanostructure of the present invention is on a bowl-shaped graphite electrode, while the SWNTs of Japanese patent application '044 are in soot.

First, the Rodriguez method will be described, which uses a cathode, an anode and a catalyst such as a metal or alloy.

Generally, as disclosed in Japanese Patent Application No. '044 and briefly disclosed in FIG. 6, the apparatus of the arc discharge method comprises a bowl-shaped graphite cathode 2
6, and carbon-containing anode 20 can be used. In addition to the method described in Japanese patent application '044, a heating coil 28 may surround the cathode 26. See FIG. 7. As a non-limiting example of a laboratory scale device, the bowl cathode 26 may have a diameter of 5 cm to 30 cm, while the anode 20 has a cross-sectional area of 0.1 to 100 cm ² , preferably 0.3 to. 3 cm ² is possible. The device can be scaled up to produce large numbers of desired core-shell nanostructures, as long as sufficient current density is obtained. If the cross section of the anode 20 is too large, then the current density may not be sufficient to carry out an arc discharge, and / or the consumption of the anode 20 is slow, which is disadvantageous.

Both the anode and the catalyst are present in an amount of 10 to 90% by weight of the carbon containing material. Preferably, the catalyst is in the range of 30 to 70% by weight of the carbon containing material, both anode and catalyst. Furthermore, this catalyst has the same composition as the hydrogen storage material 6 that is preferably contained in the core-shell type nanostructure 1. If the catalyst is included in the anode 20 and the catalyst content is too high, the catalyst melts and flows out from the anode 20. Therefore, as an alternative, a pure carbon anode 20 can be used with the catalyst in holes 24 located in a bowl-shaped graphite cathode 26. Further, the catalyst content affects the amount of the hydrogen storage substance 6 contained in the produced slit-shaped pore type carbon nanofiber 2. That is, the higher the catalyst content in the starting material, the higher the concentration of the hydrogen storage material 6 in the slit-shaped pore type carbon nanofiber 2 and the smaller the number of voids.

When arc discharge is performed using the above-mentioned device, the core-shell type nanostructure 1 is formed on the cathode.

Next, the arc CVD method will be described. Again, as disclosed in Japanese patent application '044, FIG.
As schematically shown in FIG. 1, the apparatus of the arc CVD method includes a bowl-shaped graphite anode 30 and a carbon-containing cathode 36. The anode 30 has a central hole 32 extending through the anode and a plurality of holes 34 on the surface of the anode.
including. A catalyst having the same composition as the desired hydrogen storage substance 6 to be placed inside the core-shell type nanostructure 1 is arranged in the plurality of holes 34 on the surface of the anode. Alternatively or additionally, the catalyst may be introduced into the arc plasma region with organic gas and / or the carbon-containing cathode 36.
May be included in. Further, the heating mechanism 28 may be used for the bowl type graphite anode 30. Cathode 36
May be a pure carbon rod. Alternatively, a catalyst may be included in the rod. The decomposed organic gas passes through the central hole 32 and is introduced into the arc plasma region generated by the arc discharge between the anode 30 and the cathode 36, whereby the core-shell type nanostructure 1 is generated. The temperature of the bowl type graphite anode 30 is
It is in the range 200 to 2000 ° C., and preferably in the range 600 to 1600 ° C. If the temperature of the anode is too low, the core-shell nanostructure 1 will have an unsatisfactory yield. Alternatively, if this temperature is too high, it is difficult to reach or maintain such temperature. The organic gas introduced into the arc plasma region is a gas containing 1 to 6 carbon atoms in the molecule. Preferably, the gas to be decomposed is CO, CH ₄ , CH ₂ CH
_{2 and the} like. If there are 7 or more carbon atoms per molecule, it is difficult to introduce the gas at a sufficient rate. This gas is preferably introduced into the arc plasma region at a rate in the range of 1 to 100 mm / sec. If this rate is too low, there will be insufficient carbon and catalyst source to grow the core-shell nanofibers. On the other hand,
If the gas flow rate is too high, the temperature in the arc plasma region will drop, resulting in a low product yield.

[0034]

EFFECT OF THE INVENTION f. Advantages of the Invention The present invention provides a core-shell type nanostructure 1 that is economical, safe, lightweight, and capable of expressing hydrogen absorption in a simple method.
I will provide a. In addition, hydrogen is occluded not only in the slit-shaped carbon nanofibers 2 themselves, but also in the hydrogen occluding substance 6 contained inside the carbon nanofibers 2. Body 1
Hydrogen storage capacity is increased. Furthermore, the hydrogen storage material 6 is present as nanometer-sized particles and is prevented from being oxidized by the carbon nanofibers 2, so that the kinetics of hydrogen adsorption / desorption are improved.

It is believed that many modifications can be made to the core-shell nanostructures and methods of making the same according to the present invention without departing from the spirit and scope of the invention as defined in the claims. To be

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a core-shell type nanostructure according to the present invention-a slit-shaped pore type nanofiber and a hydrogen storage substance therein.

FIG. 2 shows the core-shell type nanostructure shown in FIG.
-II is a schematic cross-sectional view taken along line II.

FIG. 3 shows the core-shell type nanostructure shown in FIG.
3 is a schematic cross-sectional view taken along line I-III.

4 is an enlarged perspective schematic view of one graphite surface of the slit-shaped pore type nanofiber shown in FIG. 1. FIG.

5A and 5B are high-resolution transmission electron microscope (TEM) photographs of core / shell nanostructures according to the present invention,
FIG. 5B is an enlarged view of FIG. 5A.

FIG. 6 is a schematic diagram of an arc discharge device for producing the core-shell type nanostructure of the present invention.

FIG. 7 is a schematic view of another arc discharge device for producing the core-shell type nanostructure of the present invention.

FIG. 8 is a schematic diagram of an arc CVD apparatus for producing the core-shell type nanostructure of the present invention.

[Explanation of symbols]

1 core-shell type nanostructure 2 slit-shaped pore type carbon nanofiber 4 graphite surface 6 hydrogen storage material 8 oxide layer 10 voids 12 slit-shaped pore type carbon nanofiber lattice spacing or graphite surface distance 20 carbon-containing anode 24 Hole 26 on Surface of Cathode 26 Bowl-type Graphite Cathode 28 Heating Mechanism 30 Bowl-type Graphite Anode 32 Through Hole in Central Part 34 Hole on Surface of Anode 30 36 Carbon-Containing Cathode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) D01F 9/127 D01F 9/127 (72) Inventor Eikotsu Tsutsui 6-735 Kitashinagawa, Shinagawa-ku, Tokyo F term in Sony Corporation (reference) 4G040 AA31 AA34 AA36 4G046 CA01 CC03 CC06 CC08 4G066 AA02B AA04B AB01A BA20 BA31 BA38 CA38 FA21 FA34 FA37 FA40 4L037 CS04 CS05 FA04 FA05 PA06 UA04

Claims (38)

[Claims] 1. A hydrogen-storing composition: slit-like carbon nanofibers in which graphite surfaces are arranged in parallel to each other around a central hole and hydrogen is occluded between the graphite surfaces. And a hydrogen storage material disposed in the central hole,
The hydrogen storage material is 10 to 90% by volume of the constituent.
The above-mentioned composition comprising: 2. The hydrogen storage material is 30 of the constituent.
A composition according to claim 1, characterized in that it is between 70 and 70% by volume. 3. The slit-shaped pore type carbon nanofiber has a cylindrical shape.
The composition described in. 4. Composition according to claim 3, characterized in that each of the graphite faces is shaped as a frustum. 5. The composition according to claim 1, wherein the slit-shaped pore type carbon nanofiber has a crystallinity of 1 to 100%. Wherein said slit-like pore type carbon nanofiber, to 25 nm ² not in the range of the cross-sectional area of 250,000Nm ^2, to the central hole portion is 1 nm ² no 1
Composition according to claim 1, characterized in that it has a cross-sectional area of 0,000 nm ² . 7. to the slit-shaped pore type carbon nanofibers 100 nm ² not in the range of the cross-sectional area of 10,000nm ^2, characterized in that said central bore portion having a cross-sectional area of 8,000 nm ² to 10 nm ² free And
The composition according to claim 1. 8. The composition according to claim 1, wherein the slit-shaped pore type carbon nanofiber has a length of 100 nm to 100 μm. 9. The composition according to claim 1, wherein the hydrogen storage material is arranged in a plurality of parts separated by a void in the central hole. 10. The composition according to claim 1, wherein the hydrogen storage material is continuously arranged in the central hole portion. 11. The hydrogen storage material includes Li, Ni,
Mg, Al, Ti, V, Nb, Ga, In, Fe, C
o, Ni, Cu, Zn, Ge, Pb, Mo, Sn, B,
C, Ir, Rh, Ru, Pt, Se, Sc, Y, La,
2. Composition according to claim 1, characterized in that Ce, Pr, Nd or Gd is mentioned. 12. The hydrogen storage material includes Mi-La,
Mg-Ni, Mg-Ce, Ca-Ni, Na-Al, N
Composition according to claim 1, characterized in that i-Ce or Ti-Fe-C is mentioned. 13. The composition of claim 1, wherein adjacent graphite faces of the graphite face are arranged at a distance of about 0.35 nm. 14. The composition of claim 1, wherein the hydrogen storage material has a hydrogen storage capacity, measured in% by volume, that is superior to the hydrogen storage capacity of the graphite surface. 15. In the hydrogen-absorbing composition: slit-shaped pore type carbon nanofibers in which graphite surfaces are arranged in parallel with each other around a central hole portion and hydrogen is absorbed between the graphite surfaces; and the central hole. A hydrogen storage material disposed in the part, wherein the hydrogen storage material is
Having a hydrogen storage capacity, measured in% by volume, superior to that of the graphite surface. 16. The hydrogen storage material is one of the constituents.
2. The content of 0 to 90% by volume.
The composition according to item 5. 17. The composition according to claim 15, wherein the slit-shaped pore type carbon nanofiber has a cylindrical shape. 18. The composition of claim 17, wherein each of the graphite surfaces is shaped as a frustum. 19. The composition according to claim 15, wherein the slit-shaped pore type carbon nanofiber has a crystallinity of 1 to 100%. 20. The slit-shaped pore type carbon nanofoil
Fiber is 25nm ^TwoTo 250,000 nm^Twoof
Within the range of cross-sectional area, the central hole is 1 nm ^TwoNo
100,000 nm^TwoCharacterized by having a cross-sectional area of
16. The composition of claim 15, which is: 21. The slit-shaped pore type carbon nanofiber, to 100 nm ² not in the range of the cross-sectional area of 10,000nm ^2, said central bore portion having a cross-sectional area of 8,000 nm ² to 10 nm ² free Composition according to claim 15, characterized. 22. The composition according to claim 15, wherein the slit-shaped pore type carbon nanofiber has a length of 100 nm to 100 μm. 23. The composition of claim 15, wherein the hydrogen storage material is disposed in the central hole in a plurality of portions separated by voids. 24. The hydrogen storage material is continuously arranged in the central hole.
The composition described in. 25. The hydrogen storage material includes Li, Ni,
Mg, Al, Ti, V, Nb, Ga, In, Fe, C
o, Ni, Cu, Zn, Ge, Pb, Mo, Sn, B,
C, Ir, Rh, Ru, Pt, Se, Sc, Y, La,
16. Composition according to claim 15, characterized in that Ce, Pr, Nd or Gd is mentioned. 26. The hydrogen storage material includes Mi-La,
Mg-Ni, Mg-Ce, Ca-Ni, Na-Al, N
Composition according to claim 15, characterized in that i-Ce or Ti-Fe-C is mentioned. 27. The composition of claim 15, wherein the graphite faces adjacent to the graphite face are arranged at a distance of about 0.35 nm. 28. Bowl-shaped
A graphite cathode, a carbon-containing electrode, and a catalyst, wherein the catalyst comprises Li, Ni, M
g, Al, Ti, V, Nb, Ga, In, Fe, Co,
Ni, Cu, Zn, Ge, Pb, Mo, Sn, B, C,
Ir, Rh, Ru, Pt, Se, Sc, Y, La, C
e, Pr, Nd, Gd, Mi-La, Mg-Ni, Mg
-Ce, Ca-Ni, Na-Al, Ni-Ce, or T
i-Fe-C; the catalyst is present in an amount of 10 to 90% by weight of the amount of carbon-containing material in the anode and in the catalyst; and in the presence of the catalyst, A core is formed on the cathode by generating an arc discharge between the cathode and the anode.
A method for producing a core-shell type nanostructure, comprising: producing a shell-type nanostructure. 29. The providing step comprises providing a bowl-shaped graphite cathode having a plurality of holes on a surface, and further wherein the catalyst is disposed within the plurality of holes. 29. The method of claim 28. 30. The method of claim 28, wherein the providing step comprises providing a carbon anode filled with the catalyst. 31. The method of claim 31, wherein the providing step comprises providing the catalyst in an amount of 30 to 70% by weight of the amount of the carbon-containing substance in the anode and in the catalyst. 28. The method according to any one of 28-30. 32. The method of claim 28, further comprising heating the cathode with a heating mechanism. 33. A bowl-shaped graphite cathode, a carbon-containing electrode, a source gas, and a catalyst, wherein the catalyst is Li,
Ni, Mg, Al, Ti, V, Nb, Ga, In, F
e, Co, Ni, Cu, Zn, Ge, Pb, Mo, S
n, B, C, Ir, Rh, Ru, Pt, Se, Sc,
Y, La, Ce, Pr, Nd, Gd, Mi-La, Mg
-Ni, Mg-Ce, Ca-Ni, Na-Al, Ni-
Ce, or Ti-Fe-C; and core-shell nanostructures on the cathode by generating an arc discharge between the cathode and the anode in the presence of the source gas and the catalyst. A method for producing a core-shell type nanostructure, which comprises producing a body. 34. The providing step provides one through hole in the anode, and further introduces the source gas from the through hole into an arc plasma range generated by the arc discharge. 34. The method of claim 33, comprising the step of: 35. The method according to claim 33, wherein the step of generating an arc discharge is carried out such that the temperature of the anode is in the range of 200 to 2000 ° C. 36. The method of claim 33, wherein the step of generating an arc discharge is carried out such that the temperature of the anode is in the range of 600 to 1600 ° C. 37. The method of claim 33, wherein said providing step comprises providing a source gas having 1 to 6 carbon atoms in the molecule. 38. The method of claim 37, wherein the providing step comprises providing CO, CH ₄ , or CH ₂ CH ₂ as the source gas.