Hydrogen storage and release material and method for producing same

Abstract

The present invention provides a hydrogen storage and release material comprising a two-dimensional borohydride-containing sheet having a two-dimensional network including n(HxBy) (n≥4, 0.001≤x / y≤0.999), in which the molar ratio of boron to hydrogen is 1:0.999 to 1:0.001, as calculated by thermal desorption spectroscopy and mass measurement before and after temperature rise, wherein: in X-ray photoelectron spectroscopy, peaks derived from B1s of boron appears at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV; and in an infrared spectroscopy, a peak derived from B-H expansion and contraction vibration appears at 2400cm-1 to 2600cm-1, and a peak derived from B-H-B expansion and contraction vibration appears at 1200 cm-1 to 1800 cm-1.

Description

[Technical field]

[0001] The present invention relates to a hydrogen storage and release material and a method for producing the same. [Background technology]

[0002] Conventionally, methods for generating hydrogen and oxygen from water include electrolysis of water (see, for example, Patent Document 1) and a method using a photocatalyst (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-67689 [Patent Document 2] Japanese Patent Application Publication No. 10-121266 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the methods described in Patent Documents 1 and 2, hydrogen and oxygen produced by the decomposition of water are generated at the same time, which poses the risk of hydrogen exploding. Therefore, in the methods described in Patent Documents 1 and 2, it is necessary to recover hydrogen and oxygen separately at different times.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a hydrogen storage and release material that can generate hydrogen and oxygen at separate times, i.e., store hydrogen from water and release the stored hydrogen at a different time from the release of oxygen, and a method for producing the same. [Means for solving the problem]

[0006] [1] The molar ratio of boron to hydrogen calculated by thermal desorption spectrometry and mass measurement before and after heating is 1:0.999 to 1:0.001 n(H x By ) (n≧4, 0.001≦x / y≦0.999) and shows peaks at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV due to boron B1s in X-ray photoelectron spectroscopy. Infrared spectroscopy shows peaks at 2400 cm -1 ~2600cm -1 The peak at 1200 cm is due to the BH stretching vibration. -1 ~1800cm -1 A hydrogen storage and release material with a peak due to BHB stretching vibration. [2] The two-dimensional boron-hydride-containing sheet has a mesh-like surface structure in which boron atoms are arranged in a hexagonal ring, and the hexagons formed by the boron atoms are connected together, and hydrogen atoms are randomly bonded to the boron atoms forming the hexagons without any particular periodic regularity and without aggregation. The hydrogen storage and release material described in [1]. [3] The hydrogen storage and release material according to [1] or [2], wherein the two-dimensional boron-hydride-containing sheet has a length of 100 nm or more in at least one direction. [4] MgB 2 The method for producing the hydrogen storage and release material according to any one of [1] to [3], comprising the steps of: mixing magnesium diboride having a type-type structure and an ion exchange resin in which magnesium ions constituting the magnesium diboride are coordinated with exchangeable ions in a polar organic solvent to obtain a precursor of a hydrogen storage and release material; and heat-treating the precursor of the hydrogen storage and release material at 110°C to 450°C. [5] The hydrogen storage and release material precursor has a molar ratio of boron to hydrogen of 1:1 as calculated by thermal desorption gas analysis and mass measurement before and after heating (HB). n (n≧4), and in X-ray photoelectron spectroscopy, it shows a peak at 188±1.0 eV due to the negatively charged B1s of boron, and in electron energy loss spectroscopy, it shows a peak at 188±1.0 eV due to the negatively charged sp 2 The method for producing a hydrogen storage and release material according to [4], having a spectrum showing a peak in the vicinity of 191±1.0 eV due to the structure. [6] The method for producing a hydrogen storage and release material according to [4] or [5], wherein the precursor of the hydrogen storage and release material includes a two-dimensional network in which boron atoms are arranged in a hexagonal ring, the hexagons formed by the boron atoms are connected to form a mesh, and two adjacent boron atoms have sites at which they bond to the same hydrogen atom. [7] The method for producing a hydrogen storage / release material according to any one of [4] to [6], wherein the ion exchange resin has a sulfo group. [8] The method for producing a hydrogen storage / release material according to any one of [4] to [7], wherein the polar organic solvent is acetonitrile. Effect of the Invention

[0007] According to the present invention, it is possible to provide a hydrogen storage / release material and a method for producing the same, which can generate hydrogen and oxygen separately from the decomposition of water, i.e., store hydrogen from water, and release the stored hydrogen at a different time from the release of oxygen. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are schematic diagrams showing the molecular structure of a two-dimensional boron-containing sheet constituting the hydrogen storage and release material of the present invention, in which (a) is a diagram showing the XY plane, (b) is a diagram showing the YZ plane, and (c) is a diagram showing the ZX plane. [Diagram 2] 1A to 1C are schematic diagrams showing the molecular structure of a hydrogen storage and release material precursor used in a method for producing a hydrogen storage and release material of the present invention, in which (a) is a diagram showing an XY plane, (b) is a diagram showing a YZ plane, and (c) is a diagram showing a ZX plane. [Diagram 3] FIG. 1 is a diagram showing the results of thermal desorption gas analysis in Experimental Examples 1 and 2. [Figure 4] FIG. 13 is a diagram showing the results of X-ray photoelectron spectroscopy in Experimental Examples 3 and 4. [Diagram 5] FIG. 13 is a diagram showing the results of infrared spectroscopy in Experimental Example 5. [Figure 6] FIG. 13 is a diagram showing the results of thermogravimetric differential thermal analysis in Experimental Example 6. [Figure 7]FIG. 13 is a diagram showing the results of gas analysis in Experimental Example 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the hydrogen storage and release material and the method for producing the same of the present invention will be described. It should be noted that the present embodiment is specifically described to allow a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0010] [Hydrogen storage and release materials] The hydrogen storage and release material of this embodiment is a boron to hydrogen molar ratio of 1:0.999 to 1:0.001, n(H x B y ) (n≧4, 0.001≦x / y≦0.999). That is, the hydrogen storage and release material of this embodiment is a sheet-like material composed of a two-dimensional boron-containing sheet having a two-dimensional network containing boron atoms (B) and hydrogen atoms (H) in a molar ratio of 1:0.999 to 1:0.001.

[0011] In the hydrogen storage and release material of this embodiment, the ratio (molar ratio) of boron atoms (B) and hydrogen atoms (H) is calculated by thermal desorption gas analysis and mass measurement before and after heating, which will be described later.

[0012] Furthermore, the two-dimensional boron hydrogen-containing sheet constituting the hydrogen storage and release material of this embodiment exhibits peaks at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV, which are attributable to B1s of boron, in X-ray photoelectron spectroscopy.

[0013] The X-ray photoelectron spectroscopy of the hydrogen storage and release material of this embodiment will be described later.

[0014] In addition, the two-dimensional boron-containing sheet constituting the hydrogen storage and release material of this embodiment has a 2400 cm -1 ~2600cm-1 The peak at 1200 cm is due to the BH stretching vibration. -1 ~1800cm -1 There is a peak due to BHB stretching vibration. That is, the two-dimensional borohydride-containing sheet constituting the hydrogen storage and release material of this embodiment has not only BH bonds but also BHB bonds.

[0015] Infrared spectroscopic analysis of the hydrogen storage and release material of this embodiment will be described later.

[0016] In the two-dimensional boron-hydride-containing sheet constituting the hydrogen storage and release material of this embodiment, as shown in Fig. 1, boron atoms (B) are arranged in a hexagonal ring like a benzene ring and exist at the vertices of the hexagon, and the hexagons formed by the boron atoms (B) are connected to form a mesh-like plane structure (two-dimensional network). Furthermore, in the two-dimensional boron-hydride-containing sheet of this embodiment, as shown in Fig. 1, hydrogen atoms (H) are randomly bonded to the boron atoms (B) forming the hexagons without any specific periodic regularity and without aggregation. For this reason, a structure is formed in which the bonds between atoms are tilted in the z direction of Fig. 1, or the sheet itself is bent. In the two-dimensional borohydride-containing sheet of this embodiment, the hexagonal network formed by the boron atoms (B) refers to, for example, a honeycomb shape.

[0017] The hydrogen storage and release material of this embodiment is a thin-film substance having a two-dimensional network containing boron atoms (B) and hydrogen atoms (H). The hydrogen storage and release material of this embodiment contains almost no magnesium derived from magnesium diboride used in the manufacturing method of the hydrogen storage and release material of this embodiment described later, or other metal atoms. In the hydrogen storage and release material of this embodiment, the total number of boron atoms (B) and hydrogen atoms (H) forming the mesh-like plane structure of the two-dimensional borohydride-containing sheet is 1000 or more.

[0018] The bond distance d between two adjacent boron atoms (B) shown in Figure 1(a) 1 is 0.155nm to 0.190nm.

[0019] The thickness of the hydrogen storage and release material of this embodiment is 0.2 nm to 10 nm. In the two-dimensional hydrogen boride-containing sheet constituting the hydrogen storage and release material of this embodiment, the length in at least one direction (for example, the length in the X direction or Y direction in FIG. 1(a)) is preferably 100 nm or more. In the hydrogen storage and release material of this embodiment, if the length in at least one direction of the two-dimensional hydrogen boride-containing sheet is 100 nm or more, the hydrogen storage and release material of this embodiment can be effectively used as a hydrogen storage and release material. The size (area) of the hydrogen storage and release material of this embodiment is not particularly limited, and can be formed to any size by the manufacturing method of the hydrogen storage and release material of this embodiment described later.

[0020] The two-dimensional borohydride-containing sheet constituting the hydrogen storage and release material of this embodiment may be terminated with an oxide, nitride, or carbide. That is, the hydrogen storage and release material of this embodiment may have an end of its molecular structure that forms an oxide, nitride, or carbide. Examples of the oxide, nitride, or carbide that forms the end of the molecular structure of the two-dimensional borohydride-containing sheet of this embodiment include boric acid (B(OH) 3 ) and boron oxide (B 2 O 3 ), hydroxyl group (OH), boron nitride (BN), and boron carbide (BC). The two-dimensional boron-hydride-containing sheet constituting the hydrogen storage and release material of this embodiment is terminated with oxide, nitride, or carbide to form a more stable molecular structure.

[0021] The two-dimensional boron-hydride-containing sheet constituting the hydrogen storage and release material of this embodiment has strong bonding forces between the boron atoms (B) forming the hexagonal rings and between the boron atoms (B) and the hydrogen atoms (H). Therefore, even if the two-dimensional boron-hydride-containing sheet of this embodiment forms a crystal (aggregate) consisting of multiple layers during production, it can be easily cleaved along the crystal plane like graphite and separated (recovered) as a single layer of two-dimensional sheet.

[0022] According to the hydrogen storage and release material of this embodiment, the molar ratio of boron to hydrogen calculated by thermal desorption gas analysis and mass measurement before and after heating is 1:0.999 to 1:0.001, n(H x B y ) (n≧4, 0.001≦x / y≦0.999) and shows peaks at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV due to boron B1s in X-ray photoelectron spectroscopy. Infrared spectroscopy shows peaks at 2400 cm -1 ~2600cm -1 The peak at 1200 cm is due to the BH stretching vibration. -1 ~1800cm -1 Since the hydrogen storage / release material has a peak derived from the BHB stretching vibration at 1000 nm, hydrogen and oxygen are not generated simultaneously, and hydrogen can be stored from water and the stored hydrogen can be released. In addition, according to the hydrogen storage / release material of this embodiment, hydrogen can be stored and released reversibly. When the hydrogen storage / release material of this embodiment stores hydrogen from water, almost only oxygen gas is released. In addition, when the hydrogen storage / release material of this embodiment releases the stored hydrogen, almost only hydrogen gas is released. Therefore, according to the hydrogen storage / release material of this embodiment, there is little risk of hydrogen explosion, and no work is required to separate hydrogen and oxygen. In addition, according to the hydrogen storage / release material of this embodiment, carbon dioxide is not generated when hydrogen is stored or released.

[0023] [Method of manufacturing hydrogen storage and release material] The method for producing the hydrogen storage and release material of this embodiment is to use MgB 2The method includes a step of mixing magnesium diboride having a molar structure with an ion exchange resin in which the magnesium ions constituting magnesium diboride are coordinated with exchangeable ions in a polar organic solvent to obtain a precursor of a hydrogen storage / release material (hereinafter referred to as the "first step"), and a step of heat-treating the precursor of the hydrogen storage / release material at 120°C to 450°C (hereinafter referred to as the "second step").

[0024] In the method for producing the hydrogen storage and release material of this embodiment, MgB 2 Magnesium diboride having a structure similar to that of magnesium diboride and an ion exchange resin in which the magnesium ions constituting magnesium diboride are coordinated with exchangeable ions are mixed in a polar organic solvent to obtain a precursor of a hydrogen storage and release material (first step).

[0025] The ion exchange resin in which the magnesium ions constituting magnesium diboride are coordinated with ion-exchangeable ions is not particularly limited, but examples thereof include a polymer of styrene having a functional group (hereinafter referred to as "functional group α") in which the magnesium ions constituting magnesium diboride are coordinated with ion-exchangeable ions, a polymer of divinylbenzene having the functional group α, and a copolymer of styrene having the functional group α and divinylbenzene having the functional group α. Examples of the functional group α include a sulfo group, a carboxyl group, etc. Among these, a sulfo group is preferred because it can easily undergo ion exchange with magnesium ions constituting magnesium diboride in a polar organic solvent.

[0026] The polar organic solvent is not particularly limited, and examples thereof include acetonitrile, N,N-dimethylformamide, methanol, etc. Among these, acetonitrile is preferred because it does not contain oxygen. In addition, magnesium diboride can easily undergo ion exchange with an ion exchange resin in a polar organic solvent.

[0027] In the first step, magnesium diboride and an ion exchange resin are added to a polar organic solvent, and the mixed solution containing the polar organic solvent, magnesium diboride, and ion exchange resin is stirred to fully contact the magnesium diboride with the ion exchange resin. As a result, magnesium ions constituting magnesium diboride are ion-exchanged with ions of the functional group α of the ion exchange resin, and a sheet-shaped hydrogen storage / release material precursor having a two-dimensional network formed by boron atoms and atoms derived from the functional group α of the ion exchange resin is produced.

[0028] If an ion exchange resin having a sulfo group is used as the ion exchange resin, the magnesium ion (Mg 2+ ) and hydrogen ions (H + ) is substituted to produce a sheet-like hydrogen storage and release material precursor having a two-dimensional network containing boron atoms (B) and hydrogen atoms (H) as described above.

[0029] In the first step, it is preferable to gently proceed with the ion exchange reaction between the magnesium ions constituting magnesium diboride and the ions of the functional group α of the ion exchange resin without applying ultrasonic waves or the like to the mixed solution.

[0030] When the mixed solution is stirred, the temperature of the mixed solution is preferably 15° C. to 35° C. The time for stirring the mixed solution is not particularly limited, but is, for example, 700 minutes to 7000 minutes.

[0031] The first step is to add nitrogen (N 2 The reaction is carried out under an inert atmosphere of an inert gas such as nitrogen (N) or argon (Ar).

[0032] Next, the mixed solution after stirring is filtered. The method of filtering the mixed solution is not particularly limited, and may be, for example, natural filtration, reduced pressure filtration, pressure filtration, centrifugal filtration, etc. As the filter material, for example, filter paper based on cellulose, membrane filter, filter plate made by compression molding cellulose or glass fiber, etc. may be used. The supernatant may be extracted without filtering.

[0033] The solution containing the product is separated from the precipitate by filtration or by extraction of the supernatant and then recovered, and is then naturally dried or dried by heating to finally obtain only the product. This product is a sheet-like hydrogen storage / release material precursor having a two-dimensional network formed by boron atoms and atoms (hydrogen: H) derived from the functional group α of the ion exchange resin.

[0034] Methods for analyzing the product obtained by the manufacturing method of the hydrogen storage and release material of this embodiment include, for example, thermal desorption gas analysis, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and the like.

[0035] In thermal desorption analysis, for example, a sample is heated in an ESCO TDS-1400TV device, and the time change in the amount of generated gas is analyzed using an attached quadrupole mass analyzer. By constructing a calibration curve based on the signal intensity of a sample whose amount of hydrogen released is known in advance, the amount of generated gas and the temperature at which it is generated can be determined.

[0036] In X-ray photoelectron spectroscopy (XPS), for example, an X-ray photoelectron spectrometer (product name: JPS9010TR) manufactured by JEOL is used to irradiate the surface of the product with X-rays and measure the energy of the photoelectrons generated at that time to analyze the constituent elements of the product and their electronic state. In this analysis, if the energy of the photoelectrons originating from magnesium constituting the raw material magnesium diboride is hardly detected, and only the energy of the photoelectrons originating from boron and the element originating from the functional group α of the ion exchange resin is detected, it can be said that the product is composed only of boron and the element originating from the functional group α of the ion exchange resin. If the element originating from the functional group α is hydrogen, it is difficult to detect it by X-ray photoelectron spectroscopy, so it is necessary to confirm the hydrogen by other analysis. If the energy of the photoelectrons originating from magnesium constituting the raw material magnesium diboride is hardly detected, and only the energy of the photoelectrons originating from boron is detected by the analysis by X-ray photoelectron spectroscopy, it can be said that the product is composed of boron.

[0037] In Fourier transform infrared spectroscopy (FT-IR), for example, an FT / IR-300 instrument manufactured by JASCO Corporation is used to analyze the absorption intensity resulting from vibrations associated with the bond between boron and hydrogen, and the presence of oxygen functional groups, etc.

[0038] The sheet-shaped hydrogen storage and release material precursor obtained in the first step of the method for producing a hydrogen storage and release material of this embodiment has a molar ratio of boron and hydrogen of 1:1 (HB). n (n≧4). That is, the sheet-shaped hydrogen storage / release material precursor is a sheet-shaped material having a two-dimensional network containing boron atoms (B) and hydrogen atoms (H) in a molar ratio of 1:1.

[0039] In the sheet-shaped hydrogen storage / release material precursor, the ratio (molar ratio) of boron atoms (B) and hydrogen atoms (H) is calculated by thermal desorption gas analysis and mass measurement before and after heating, which will be described later.

[0040] Furthermore, in X-ray photoelectron spectroscopy, the sheet-shaped hydrogen storage / release material precursor exhibits a peak at 188±1.0 eV, which is attributable to the B1s of negatively charged boron.

[0041] In addition, the sheet-shaped hydrogen storage and release material precursor showed boron sp 2 The spectrum shows a peak at 191±1.0 eV due to the structure.

[0042] The electron energy loss spectroscopy of the sheet-shaped hydrogen storage and release material precursor will be described later.

[0043] In the sheet-shaped hydrogen storage and release material precursor, as shown in FIG. 2, boron atoms (B) are arranged in a hexagonal ring like a benzene ring, and are present at the vertices of the hexagon, and the hexagons formed by the boron atoms (B) are connected to form a mesh-like plane structure (two-dimensional network). Furthermore, in the sheet-shaped hydrogen storage and release material precursor, as shown in FIG. 2, two adjacent boron atoms (B) have a site where they are bonded to the same hydrogen atom (H). In the sheet-shaped hydrogen storage and release material precursor, the hexagonal mesh formed by the boron atoms (B) refers to, for example, a honeycomb shape. Furthermore, the hydrogen atoms (H) may or may not have a specific periodic regularity to the boron atoms (B) forming the hexagons as shown in FIG. 2, and are bonded randomly without aggregation. For this reason, a structure is formed in which the bonds between atoms are tilted in the z direction of FIG. 2, or the sheet itself is bent.

[0044] The sheet-shaped hydrogen storage and release material precursor is a thin film-like substance having a two-dimensional network containing boron atoms (B) and hydrogen atoms (H). In addition, the sheet-shaped hydrogen storage and release material precursor contains almost no magnesium atoms derived from magnesium diboride used in the manufacturing method of the hydrogen storage and release material or other metal atoms. In the sheet-like precursor of the hydrogen storage and release material, the total number of boron atoms (B) and hydrogen atoms (H) forming the above-mentioned mesh-like plane structure is 1000 or more.

[0045] The bond distance D between two adjacent boron atoms (B) shown in Figure 2(a) 1 is 0.155 nm to 0.190 nm. In addition, the bond distance D between two adjacent boron atoms (B) via one hydrogen atom (H) shown in FIG. 2(b) is 2 is 0.155 nm to 0.190 nm. In addition, the bond distance D between adjacent boron atoms (B) and hydrogen atoms (H) shown in FIG. 2(b) is 3 is 0.12nm to 0.15nm.

[0046] The thickness of the sheet-shaped hydrogen storage and release material precursor is 0.20 nm to 10.00 nm. In the sheet-shaped hydrogen storage and release material precursor, it is preferable that the length in at least one direction (for example, the length in the X direction or the Y direction in FIG. 2(a)) is 100 nm or more. The size (area) of the sheet-shaped hydrogen storage and release material precursor is not particularly limited, and can be formed to any size by the first step of the manufacturing method of the hydrogen storage and release material of the present embodiment.

[0047] The sheet-shaped hydrogen storage and release material precursor may be terminated with an oxide, nitride, or carbide. In other words, the molecular structure of the sheet-shaped hydrogen storage and release material precursor may have an end that forms an oxide, nitride, or carbide. Examples of the oxide, nitride, or carbide that forms the end of the molecular structure of the sheet-shaped hydrogen storage and release material precursor include boric acid (B(OH) 3 ) and boron oxide (B 2 O 3 ), hydroxyl groups (OH), boron nitride (BN), and boron carbide (BC). The sheet-shaped hydrogen storage and release material precursor is terminated with oxides, nitrides, or carbides to form a more stable molecular structure.

[0048] The sheet-shaped precursor of the hydrogen storage and release material has strong bonding forces between the boron atoms (B) that form the hexagonal rings, and between the boron atoms (B) and the hydrogen atoms (H). Therefore, even if the sheet-shaped precursor of the hydrogen storage and release material forms an aggregate consisting of multiple layers during production, it can be easily cleaved along the sheet surface, just like graphite, and separated (recovered) as a single two-dimensional sheet.

[0049] Next, the sheet-shaped hydrogen storage / release material precursor is heat-treated at 120° C. to 450° C. to obtain the hydrogen storage / release material of this embodiment (second step).

[0050] In the second step, the time for which the sheet-shaped hydrogen storage / release material precursor is heat-treated is not particularly limited, but is set to, for example, 5 minutes to 1200 minutes.

[0051] The second step is carried out under vacuum or nitrogen (N 2 The reaction is carried out under an inert atmosphere of an inert gas such as nitrogen (N) or argon (Ar).

[0052] According to the manufacturing method of the hydrogen storage and release material of this embodiment, it is possible to easily produce a hydrogen storage and release material composed of a two-dimensional boron compound-containing sheet having a two-dimensional network containing boron atoms and atoms (hydrogen: H) derived from the functional group α of the ion exchange resin. The raw material MgB 2 By using large crystals of magnesium diboride having the above-mentioned structure, it is possible to obtain a sheet-shaped hydrogen storage and release material precursor having a larger area, which results in a sheet-shaped hydrogen storage and release material having a larger area.

[0053] Furthermore, according to the manufacturing method of the hydrogen storage and release material of this embodiment, in the first step of forming a sheet-shaped hydrogen storage and release material precursor, a polar organic solvent is used instead of an acidic solution to perform ion exchange between the magnesium ions that constitute magnesium diboride and the ions of the functional group α of the ion exchange resin, so there is no need to adjust the pH of the mixed solution containing the polar organic solvent, magnesium diboride, and ion exchange resin. EXAMPLES

[0054] The present invention will be described in more detail below with reference to experimental examples, but the present invention is not limited to the following experimental examples.

[0055] [Experimental Example 1] 500 mg of magnesium diboride (purity: 99%, manufactured by Rare Metallic Co., Ltd.) was added to acetonitrile, and 30 mL of an ion exchange resin having a sulfo group (Amberlite (registered trademark) IR120B, manufactured by Organo Corporation) was added by volume, and the mixture was stirred with a glass rod to prepare a mixed solution of magnesium diboride and the ion exchange resin. After stirring this mixed solution at 25°C for 72 hours, this mixed solution was filtered through a membrane filter with a pore size of 1.0 μm, and the filtrate was collected. The filtrate was then dried at 90°C using a hot plate under a nitrogen atmosphere to obtain a product (precursor of hydrogen storage and release material). The obtained product was subjected to thermal desorption gas analysis and mass measurement before and after heating, and the molar ratio of boron to hydrogen was calculated. For the thermal desorption gas analysis, a TDS-1400TV device manufactured by ESCO was used. For the mass measurement before and after heating, an analytical balance ITX220 device manufactured by AS ONE was used. The mass was measured in a vacuum type glove box (vacuum type glove box UN-800L-BG manufactured by UNICO). The results of the thermal desorption gas analysis are shown in Figure 3.

[0056] [Experimental Example 2] The product of Experimental Example 1 (precursor of the hydrogen storage / release material) was heated in a vacuum at 350° C. for 1 hour to obtain a product, and another product was heated in a vacuum at 450° C. to obtain a product. For the obtained product, the molar ratio of boron to hydrogen was calculated in the same manner as in Experimental Example 1.

[0057] It was found that the product (hydrogen storage and release material precursor) obtained in Experimental Example 1 had a molar ratio of boron (B) and hydrogen (H) of 1:1. The specific calculation method is as follows. A calibration curve is constructed based on the signal intensity of a sample whose amount of hydrogen released is known in advance, the number of moles of hydrogen released is calculated using the signal intensity obtained in Figure 3, and the molar ratio of boron and hydrogen is calculated from the sample mass measured in advance. Using a similar method, it was found that the product obtained in Experimental Example 2 had a molar ratio of boron (B) and hydrogen (H) of 1:0.73 when heated at 350°C and 1:0.57 when heated at 450°C.

[0058] [Experimental Example 3] The product (hydrogen storage and release material precursor) obtained in Experimental Example 1 was subjected to X-ray photoelectron spectroscopy analysis using an X-ray photoelectron spectroscopy analyzer (product name: JPS9010TR) manufactured by JEOL Co., Ltd. The results of the X-ray photoelectron spectroscopy analysis are shown as the figure marked "20°C" in FIG.

[0059] [Experimental Example 4] The product (hydrogen storage / release material precursor) obtained in Experimental Example 1 was heated in vacuum at 350° C. for 1 hour to obtain a sample, which was subjected to X-ray photoelectron spectroscopy analysis in the same manner as in Experimental Example 3. The results of the X-ray photoelectron spectroscopy analysis are shown in the figure marked "350° C." in FIG. 4.

[0060] As shown in FIG. 4, the product of Experimental Example 3 was confirmed to have a spectrum showing a peak at 187 eV due to B1s of boron and no peak due to magnesium in X-ray photoelectron spectroscopy. This result shows that magnesium diboride (MgB 2 ) Mg 2+ This suggests that ions were exchanged with hydrogen ions of the sulfo groups of the ion exchange resin. Experimental Example 4 shows that some hydrogen has been removed from this sample.

[0061] [Experimental Example 5] The product (hydrogen storage / release material precursor) obtained in the same manner as in Experimental Example 1 was heated in a vacuum to 30°C, 50°C, 100°C, 120°C, 200°C, 250°C, 300°C, 350°C or 400°C, and the sample was subjected to infrared spectroscopic analysis in a vacuum while still in that state. For the infrared spectroscopic analysis, a Fourier transform infrared spectrometer (FT-IR, product name: Alpha, manufactured by Bruker) was used. The results of the infrared spectroscopic analysis are shown in FIG. As shown in FIG. 5, in all cases, the product had an infrared absorption spectrum of 2500 cm -1 It has a peak due to BH stretching vibration around 1700 cm -1 Near and 1200 cm -1 It was confirmed that there was a peak due to BHB stretching vibration around 1200cm. -1 It can be seen that the peak derived from the BHB stretching vibration near 200°C can be confirmed up to 250°C, and has extremely low intensity above 300°C. From the results of Experimental Examples 1 to 5, the product of Experimental Example 2 obtained by heating the hydrogen storage and release material precursor to 350°C has a molar ratio of boron to hydrogen of 1:0.73 calculated by thermal desorption gas analysis and mass measurement before and after heating, and has a spectrum showing peaks at 187 eV and 191 eV derived from B1s of boron and no peak derived from magnesium in X-ray photoelectron spectroscopy, and has a peak at 2400 cm -1 ~2600cm -1 The peak at 1200 cm is due to the BH stretching vibration. -1 ~1800cm -1 It was found that the product of Experimental Example 2 had a peak due to the BHB stretching vibration. x B y ) (n≧4, 0.001≦x / y≦0.999).

[0062] [Experimental Example 6] The hydrogen storage and release performance of the product obtained in Experimental Example 1 was confirmed using an infrared heating furnace and water vapor differential thermobalance TG-DTA (product name: TG-DTA / HUM-1, manufactured by Rigaku Corporation) in the following manner. First, about 10 mg of a sample (the product obtained in Experimental Example 1) was weighed. Since this sample is hygroscopic, it was quickly collected and the mass collected in the platinum container was used instead of weighing exactly 10 mg (the target value). Next, the platinum container containing the sample was placed in an infrared heating furnace and a water vapor differential thermobalance TG-DTA. The atmosphere inside the device in which the platinum container was placed was argon with a purity of 99.99% or higher, and 20% by volume of water vapor was introduced only when hydrogen was being stored. The atmosphere in the apparatus was heated and held at 120°C for 30 minutes, and the moisture adsorbed on the sample was desorbed to obtain the initial mass of the sample. The temperature was then raised and held at 300°C for 30 minutes, hydrogen was desorbed, and the mass loss was measured. The temperature was then lowered to 80°C and held for 10 minutes, after which 20% by volume of water vapor was introduced and held for 60 minutes, and the introduction of water vapor was stopped and the sample was held at 80°C for another 10 minutes. The sample was then heated to 120°C and held for 10 minutes to measure the dry mass of the sample excluding the adsorbed water. The sample was again heated to 300°C and held for 30 minutes to measure the amount of hydrogen desorption as the loss from the dry mass. One cycle was 300°C → 80°C → steam introduction / stop → 120°C, and this cycle was repeated 10 times. The results of thermogravimetric differential thermal analysis are shown in FIG. From the results shown in Figure 6, it was confirmed that the mass of the sample decreased when it was heated to 300°C. It is believed that the decrease in the mass of the sample is due to the release of hydrogen stored in the sample when it is heated to 300°C. On the other hand, it was confirmed that the mass of the sample increased when water vapor was introduced at 80°C. It is believed that the increase in the mass of the sample is due to the contact with water vapor in the atmosphere, the adsorption of moisture, and the storage of hydrogen. Oxygen is generated when the sample stores hydrogen from the water vapor in the atmosphere. Furthermore, as shown in Figure 6, the sample can repeatedly store and release hydrogen.

[0063] Here, the difference between the mass of the sample after drying and the mass of the sample after being held at 300°C is defined as the hydrogen storage amount, and the initial hydrogen storage amount A of the sample is calculated based on the following formulas (1) and (2). (0) (mass%), hydrogen storage amount A of the sample after the nth regeneration (n) (% by mass) was calculated. A (0) =(W dry -W 1(0) ) / W dry ×100 (1) A (n) =(W 2(n) -W 3(n) ) / W dry ×100 (2) However, in the above formulas (1) and (2), W dry is the mass of the sample after drying, W 1(0) is the mass of the sample after 30 minutes of hydrogen release (held at 300°C), W 2(n) is the mass after drying at 120°C for 10 minutes after introducing water vapor at 80°C, W 3(n) is the mass of the sample after hydrogen release (held at 300°C). The results are shown in Table 1.

[0064] [Table 1]

[0065] From the results shown in Table 1, it was found that the amount of hydrogen storage increased from the initial stage to the second regeneration. In addition, from the second to the ninth regenerations, the amount of hydrogen storage was almost constant, although there was some variation. The average amount of hydrogen storage from the second to the ninth regenerations was 14.2 mass%. In addition, the regenerated sample was orange in color, which suggests that there is a high possibility that the regenerated sample stored hydrogen.

[0066] [Experimental Example 7] The hydrogen storage performance of the product obtained in Experimental Example 1 was confirmed by carrying out gas analysis using a gas chromatograph (product name: TCD Gas Chromatograph GC-8A, manufactured by Shimadzu Corporation) according to the following procedure. The columns used were (product name: Molecular Sieve 5A, manufactured by GL Sciences, Inc., and product name: Porapak Q, manufactured by Waters Corporation). In the gas analysis using this gas chromatograph, the column temperature was 120°C, and the injection port and detector temperatures were 140°C. The current value in the thermal conductivity detector (GC / TCD) was 60 mA. The flow rate of the argon carrier gas was 30 mL / min.

[0067] First, about 100 mg of a sample (the product obtained in Experimental Example 1) was weighed and placed in a cylindrical stainless steel reaction vessel equipped with sealing valves on both ends. The reaction vessel containing the sample was placed in a catalytic reaction apparatus, and with both sealing valves open, the reaction vessel was heat-treated at 250°C for 2 hours under argon flow (argon flow rate 25 mL / min), and then the temperature was lowered and held at 90°C for 30 minutes with both sealing valves closed. The gas (hydrogen) in the reaction vessel was then quantitatively analyzed by the gas chromatograph (step 1). Next, with both sealing valves open, the reaction vessel was maintained at 90°C for 30 minutes under argon flow (argon flow rate 25 mL / min). After that, with both sealing valves closed, 0.10 mL of water was introduced into the reaction vessel from the injection port and maintained at 90°C for 1 hour. Then, the gas (oxygen) in the reaction vessel was quantitatively analyzed by the above gas chromatograph (step 2). "Step 1 → Step 2" was defined as the 0th cycle, i.e., pretreatment. Next, with both sealing valves open, the reaction vessel was held at 90° C. for 30 minutes under argon flow (argon flow rate 25 mL / min). After that, with both sealing valves closed, the reaction vessel was heated to 250° C., and after the heating, the reaction vessel was held at 250° C. for 30 minutes. Then, the gas (hydrogen) in the reaction vessel was quantitatively analyzed by the gas chromatograph (step 3). The above "step 3 → step 2" was counted as one cycle, and was repeated 10 times, which were designated as the 1st to 10th cycles. The amounts of hydrogen gas measured in step 3 and the amounts of oxygen gas measured in step 2 in the 1st to 10th cycles are shown in FIG. 7.

[0068] As shown in Figure 7, H 2 and O 2 It was confirmed that the molar ratio of was close to 2:1, and it was found that the water molecules were converted into hydrogen and oxygen. In other words, it was confirmed that the product obtained in Experimental Example 1 repeatedly stored and released hydrogen from the water introduced into the reaction vessel. [Industrial Applicability]

[0069] The hydrogen storage and release material of the present invention can be used to generate hydrogen and oxygen as a new method for producing hydrogen and oxygen from water, and has the potential to become a core material for a hydrogen society.

Claims

1. A material for reversible hydrogen storage and release, comprising: The molar ratio of boron to hydrogen calculated by thermal desorption gas analysis and mass measurement before and after heating is 1:0.999 to 1:0.001, n(H ｘ B ｙ ) (n≧4, 0.001≦x / y≦0.999), In X-ray photoelectron spectroscopy, peaks at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV due to boron B1s are shown. Infrared spectroscopy revealed a peak at 2400 cm －１ ~2600cm －１ It has a peak due to B-H stretching vibration at 1200 cm －１ ~1800cm －１ has a peak due to B-H-B stretching vibration, The reversible hydrogen storage and release material reversibly stores and releases hydrogen, The reversible hydrogen storage / release material releases hydrogen when heated to 120° C. to 450° C.; The reversible hydrogen storage / release material, which has released hydrogen, stores hydrogen when in contact with water.

2. The two-dimensional boron-hydride-containing sheet has a mesh-like surface structure in which boron atoms are arranged in a hexagonal ring, and the hexagons formed by the boron atoms are connected together, and hydrogen atoms are randomly bonded to the boron atoms forming the hexagons without any particular periodic regularity and without aggregation. The reversible hydrogen storage and release material according to claim 1, characterized in that the two-dimensional boron-hydride-containing sheet has a mesh-like surface structure in which the hexagons formed by the boron atoms are connected together, and hydrogen atoms are randomly bonded to the boron atoms forming the hexagons without any particular periodic regularity and without aggregation.

3. 3. The reversible hydrogen storage and release material according to claim 1, wherein the two-dimensional borohydride-containing sheet has a length of 100 nm or more in at least one direction.

4. MgB ２ A step of mixing magnesium diboride having a structure of a hydrogen storage and release material with an ion exchange resin in which magnesium ions constituting the magnesium diboride and ion exchangeable ions are coordinated in a polar organic solvent to obtain a hydrogen storage and release material precursor; The method for producing the reversible hydrogen storage and release material according to any one of claims 1 to 3, further comprising the step of heat-treating the hydrogen storage and release material precursor at 120°C to 450°C.

5. The hydrogen storage and release material precursor has a molar ratio of boron to hydrogen of 1:1 (HB) as calculated by thermal desorption gas analysis and mass measurement before and after heating. ｎ (n≧4), and in X-ray photoelectron spectroscopy, it shows a peak at 188 eV±1.0 eV due to the B1s of negatively charged boron, and in electron energy loss spectroscopy, it shows a peak at 188 eV±1.0 eV due to the sp ２ The method for producing a reversible hydrogen storage and release material according to claim 4, characterized in that the material has a spectrum showing a peak at 191 eV±1.0 eV due to its structure.

6. The method for producing a reversible hydrogen storage and release material according to claim 4 or 5, characterized in that the hydrogen storage and release material precursor includes a two-dimensional network in which boron atoms are arranged in a hexagonal ring, the hexagons formed by the boron atoms are connected to form a mesh, and two adjacent boron atoms have sites at which they bond to the same hydrogen atom.

7. 7. The method for producing a reversible hydrogen storage / release material according to claim 4, wherein the ion exchange resin has a sulfo group.

8. The method for producing a reversible hydrogen storage and release material according to any one of claims 4 to 7, characterized in that the polar organic solvent is acetonitrile.

9. A reversible hydrogen storage and release method comprising heating a hydrogen storage and release material to 120°C to 450°C to release hydrogen, and contacting the hydrogen storage and release material from which hydrogen has been released with water to store hydrogen, The hydrogen storage and release material has a molar ratio of boron to hydrogen of 1:0.999 to 1:0.001, calculated by thermal desorption gas analysis and mass measurement before and after heating, n(H ｘ B ｙ ) (n≧4, 0.001≦x / y≦0.999), In X-ray photoelectron spectroscopy, peaks at 187.5±1.0 eV and 191.2±1.0 eV to 193±1.0 eV due to boron B1s are shown. Infrared spectroscopy revealed a peak at 2400 cm －１ ~2600cm －１ It has a peak due to B-H stretching vibration at 1200 cm －１ ~1800cm －１ The reversible hydrogen storage and release method is characterized in that a peak derived from BHB stretching vibration is present at

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