Ti4O7-MgH2 composite hydrogen storage material and preparation method thereof

Abstract

The invention belongs to the field of nano material preparation, discloses a Ti4O7-MgH2 composite hydrogen storage material and a preparation method thereof, and aims to solve the technical problems that MgH2 is slow in hydrogen absorption dynamics, high in initial hydrogen absorption and desorption temperature and difficult in low-temperature hydrogen absorption. In a hydrogen atmosphere, Ti4O7 and MgH2 with multivalent Ti and oxygen vacancies are subjected to ball milling, Ti4O7-MgH2 is obtained, and the composite hydrogen storage material is obtained. The Ti4O7-MgH2 composite hydrogen storage material provided by the invention has the advantages of low initial hydrogen desorption temperature and excellent constant-temperature hydrogen absorption dynamic performance. The hydrogen absorption activation energy of the composite material is reduced to 33.92 KJ / mol; under the condition of 250 DEG C, the hydrogen absorption amount can reach saturation in only 2 minutes; and under the conditions of 50 DEG C and 2 hours, the hydrogen absorption capacity can reach 1.7 wt.%. The composite material is prepared through a ball milling method, the method is simple, energy consumption is low, and potential industrial production value is achieved.

Description

Technical Field

[0001] The invention relates to the field of nano material preparation, and in particular to a composite hydrogen storage material. Background Art

[0002] Hydrogen energy is a clean, efficient, and renewable energy source. It is known as the new energy of the 21st century and has attracted people's attention. However, the development and application of hydrogen energy involves four key areas: hydrogen preparation, storage, transportation, and application. Hydrogen itself has the disadvantages of being flammable and explosive, and has low volume energy density at room temperature and pressure. Therefore, hydrogen storage technology has become a key issue restricting the large-scale application of hydrogen energy.

[0003] At present, the main hydrogen storage methods are high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and solid-state hydrogen storage. Solid-state hydrogen storage has been widely studied by researchers because of its advantages such as large hydrogen storage density, strong safety and excellent recyclability. At present, solid-state hydrogen storage is divided into metal hydrides, coordination hydrides, physical adsorption materials and other hydrogen storage materials. Due to its large hydrogen storage density, low cost and abundant reserves, magnesium hydride is considered to be one of the most promising hydrogen storage materials, and its theoretical hydrogen storage capacity is as high as 7.6wt.%. However, due to the strong ionic bond of magnesium hydride, the kinetics of hydrogen absorption and desorption are slow and the temperature of hydrogen absorption and desorption is high, which limits the application of magnesium hydride. Therefore, researchers modify magnesium hydride by nano-ization, alloying, composite and introducing catalysts, but there is a problem of unstable hydrogen absorption and desorption cycle when magnesium hydride is nano-ized, alloyed and composited. Introducing a small amount of catalyst to modify the hydrogen storage performance of magnesium hydride is one of the hot spots that researchers are most concerned about at present, and it is also one of the simplest and most efficient methods for modifying magnesium hydride. Catalysts can weaken the ionic bond energy between Mg-H, reduce the activation energy of magnesium hydride dehydrogenation, and reduce the initial dehydrogenation temperature of magnesium hydride; catalysts can also promote the dissociation of hydrogen into hydride ions, providing channels for the nucleation of hydride ions and Mg, so the introduction of catalysts is an effective method to improve the hydrogen storage performance of magnesium hydride. The paper "Hydrogen sorption ofmagnesium hydride doped with nano-sized TiO2" reported the hydrogen storage performance of magnesium hydride modified by rutile phase TiO2. Rutile phase TiO2 and magnesium hydride were prepared by ball milling. The composite material took 3 minutes to absorb hydrogen at 300°C and took 10 minutes to absorb hydrogen to 3.54wt.%. Compared with the original magnesium hydride, the hydrogen storage performance of the composite material was improved. However, the composite material needs to absorb hydrogen at high temperature, and the hydrogen absorption is low and the hydrogen absorption rate is slow, which seriously limits its commercial application and promotion. Summary of the invention

[0004] In order to solve the technical problems of slow hydrogen absorption rate, high initial hydrogen absorption and desorption temperature and difficulty in low-temperature hydrogen absorption of magnesium hydride, the present invention proposes a Ti4O7-MgH2 composite hydrogen storage material and a preparation method thereof.

[0005] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0006] A Ti4O7-MgH2 composite hydrogen storage material, wherein Ti4O7 is loaded on the surface of MgH2. Ti4O7 has oxygen vacancies, and Ti has +3 and +4 valences. The present invention uses Ti4O7 as a catalyst to improve the hydrogen storage performance of magnesium hydride by weakening the bond energy of magnesium hydride and providing a channel for the migration of hydrogen anions. Specifically, Ti in Ti4O7 has Ti 3+ and Ti 4+ , and has oxygen vacancies. Ti 3+ and Ti 4+ There is an empty orbital in the 3d orbital of MgH2. During the dehydrogenation process, the empty orbital can accept H - electrons, reducing it to H2; during the process of MgH2 absorbing hydrogen, Ti 3+ The lone electron in the 3d orbital of H2 is returned to the σ orbital of H2, dissociating into H - , Ov is H - It provides a channel for the migration of hydrogen and improves the kinetic properties of hydrogen storage materials.

[0007] The mass percentage of Ti4O7 in the above composite hydrogen storage material is 1-10wt%. Too high a mass percentage of Ti4O7 will affect the hydrogen storage content of the composite material, and too much catalyst will also hinder the active sites of MgH2 for hydrogen absorption and desorption. Therefore, the content of Ti4O7 needs to be controlled within an appropriate range.

[0008] The hydrogen absorption activation energy of the above Ti4O7-MgH2 composite hydrogen storage material is reduced to 33.92 KJ / mol.

[0009] The Ti4O7-MgH2 composite hydrogen storage material absorbs 6.7 wt.% of hydrogen in 30 seconds at 250°C, reaches saturation of hydrogen absorption in 2 minutes, and has a maximum hydrogen absorption of 6.8 wt.%.

[0010] The above Ti4O7-MgH2 composite hydrogen storage material can absorb hydrogen up to 1.7wt.% under the conditions of 50°C and 2h.

[0011] The preparation method of the above-mentioned Ti4O7-MgH2 composite hydrogen storage material comprises the following steps: ball milling Ti4O7 and MgH2 in a hydrogen atmosphere to obtain the obtained material.

[0012] Furthermore, the mass of the above-mentioned Ti4O7 accounts for 1-10% of the total mass of Ti4O7 and MgH2.

[0013] Furthermore, in the above-mentioned ball-to-material ratio, the ball-to-material ratio is 150-180:1, the ball-milling speed is 300-700rpm / min, and the ball-milling time is 3-6h. Too low a ball-to-material ratio, low speed, and short ball-milling time will cause the composite material to be uneven during the ball-milling process; too high a ball-to-material ratio, too fast a ball-milling speed, and long a ball-milling time will cause more composite materials to adhere to the metal balls, resulting in greater losses. By regulating the ball-to-material ratio, the ball-milling speed, and the ball-milling time, the composite material can be evenly distributed while reducing energy consumption.

[0014] The beneficial effects produced by the present invention are:

[0015] (1) The present invention proposes a Ti4O7-MgH2 composite hydrogen storage material, the hydrogen absorption activation energy of which is as low as 33.92 KJ / mol, and has a relatively low hydrogen absorption temperature (i.e., it can absorb hydrogen at 50°C). 3+ and Ti 4+ , and has oxygen vacancies. Ti 3+ and Ti 4+ There is an empty orbital in the 3d orbital of MgH2. During the dehydrogenation process, the empty orbital can accept H - electrons, reducing it to H2; during the process of MgH2 absorbing hydrogen, Ti 3+ The lone electron in the 3d orbital of H2 is returned to the σ orbital of H2, dissociating into H - , Ov is H - It provides a channel for the migration of hydrogen and improves the kinetic properties of hydrogen storage materials.

[0016] (2) The Ti4O7-MgH2 composite hydrogen storage material proposed in the present invention has a low initial dehydrogenation temperature and excellent isothermal hydrogen absorption kinetics. Specifically, when the mass fraction of Ti4O7 in the composite material is 7wt.%, the initial dehydrogenation temperature is 241°C. In addition, when the mass fraction of Ti4O7 is 7wt.%, the composite material absorbs hydrogen at 250°C, and the hydrogen absorption amount can reach about 95% of the theoretical value (the theoretical value is 7.068wt.%) in just 30s, and the hydrogen absorption amount reaches the maximum hydrogen absorption capacity in just 2min; at 50°C, 2h, the hydrogen absorption amount can reach 1.7wt.%, which has the advantage of low-temperature hydrogen absorption.

[0017] (3) The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of the present invention is simple and has low energy consumption. It can be obtained by ball milling Ti4O7 and MgH2 in a hydrogen environment for 3-6 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is the SEM of the composite hydrogen storage material prepared in Example 1 of the present invention.

[0020] Figure 2 This is the XRD of the composite hydrogen storage material prepared in Example 3 of the present invention.

[0021] Figure 3 The temperature-dependent hydrogen release curves of the composite hydrogen storage materials prepared in Examples 1-4 of the present invention are shown.

[0022] Figure 4 This is a temperature-dependent hydrogen release curve of the unmodified magnesium hydride in Comparative Example 1 of the present invention.

[0023] Figure 5 This is a graph of the hydrogen absorption activation energy of the composite hydrogen storage material prepared in Example 3 of the present invention; wherein (a) is the hydrogen absorption JMAK equation; and (b) is the hydrogen absorption Arrhenius equation.

[0024] Figure 6 The isothermal hydrogen absorption curves of the composite hydrogen storage material prepared in Example 3 of the present invention at different temperatures; wherein (a) is the isothermal hydrogen absorption curve from 0 to 120 min; and (b) is an enlarged view of the isothermal hydrogen absorption curve from 0 to 20 min in (a).

[0025] Figure 7 This is the isothermal hydrogen absorption curve of the unmodified magnesium hydride at 250°C in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0029] 0.03g of Ti4O7 and 0.97g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400r / min, and a ball milling time of 4h to obtain Ti4O7-3wt.%-MgH2, i.e., a composite hydrogen storage material. Figure 1 This is a SEM of the composite hydrogen storage material prepared in Example 1 of the present invention. It can be seen from the figure that Ti4O7 is attached to the surface of MgH2, and Ti4O7 provides a large number of active sites for MgH2 to absorb and release hydrogen.

[0030] Example 2

[0031] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0032] 0.05g of Ti4O7 and 0.95g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400r / min, and a ball milling time of 4h to obtain Ti4O7-5wt.%-MgH2, i.e., a composite hydrogen storage material.

[0033] Example 3

[0034] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0035] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400r / min, and a ball milling time of 4h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0036] Figure 2 This is the XRD of the composite hydrogen storage material prepared in this example. It can be observed from the XRD spectrum that the sample after ball milling contains only MgH2 and Ti4O7, which proves that the sample is not contaminated and oxidized during the ball milling process.

[0037] Example 4

[0038] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0039] 0.1g of Ti4O7 and 0.9g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400r / min, and a ball milling time of 4h to obtain Ti4O7-10wt.%-MgH2, i.e., a composite hydrogen storage material.

[0040] Example 5

[0041] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0042] 0.01g of Ti4O7 and 0.99g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400r / min, and a ball milling time of 4h to obtain Ti4O7-1wt.%-MgH2, i.e., a composite hydrogen storage material.

[0043] Example 6

[0044] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0045] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 0.5MPa of hydrogen was filled into the ball mill and ball milling was performed in a hydrogen atmosphere with a ball-to-material ratio of 150:1, a rotation speed of 380r / min, and a ball milling time of 4h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0046] Example 7

[0047] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0048] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 0.5MPa of hydrogen was filled into the ball mill and ball milling was performed in a hydrogen atmosphere with a ball-to-material ratio of 155:1, a rotation speed of 350r / min, and a ball milling time of 4h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0049] Example 8

[0050] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0051] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 0.5MPa of hydrogen was filled into the ball mill and ball milling was performed in a hydrogen atmosphere with a ball-to-material ratio of 165:1, a rotation speed of 450r / min, and a ball milling time of 5h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0052] Example 9

[0053] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0054] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 0.5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 150:1, a rotation speed of 700r / min, and a ball milling time of 3h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0055] Example 10

[0056] The preparation method of the Ti4O7-MgH2 composite hydrogen storage material of this embodiment comprises the following steps:

[0057] 0.07g of Ti4O7 and 0.93g of commercial magnesium hydride were placed in a ball mill in an argon environment glove box. 0.5MPa of hydrogen was filled into the ball mill and ball milling was performed under hydrogen atmosphere with a ball-to-material ratio of 180:1, a rotation speed of 300r / min, and a ball milling time of 6h to obtain Ti4O7-7wt.%-MgH2, i.e., a composite hydrogen storage material.

[0058] Comparative Example 1

[0059] 1.00 g of commercial magnesium hydride was placed in a ball mill in a glove box with an argon environment. The ball mill was filled with 0.5 MPa of hydrogen and ball milled in a hydrogen atmosphere with a ball-to-material ratio of 160:1, a rotation speed of 400 r / min, and a ball milling time of 4 h to obtain unmodified magnesium hydride.

[0060] Implementation effect example

[0061] (1) Temperature-dependent hydrogen release performance test

[0062] Place the sample in the reactor in the glove box, then close the reactor valve, take the reactor out of the glove box and place it in the heating device, connect the reactor to the test equipment and evacuate the reactor to a vacuum state through the test hydrogen release device, heat the heating device from room temperature to 500°C at a heating rate of 5°C / min, and the test equipment starts recording the sample hydrogen release data when the heating device starts heating until the heating ends. Figure 3As shown, when the mass fraction of Ti4O7 in the composite material is 7wt.%, the initial dehydrogenation temperature is 241℃, which is relatively lower than 281℃ and 291℃ of 5wt.% and 3wt.% respectively; when the mass fraction of Ti4O7 is 10wt.%, the initial dehydrogenation temperature of the composite material is 274℃. When the catalyst content is too much, the active sites of MgH2 releasing hydrogen are hindered, making the diffusion of H2 slow. Under certain conditions, when the mass fraction of Ti4O7 is higher, it can better catalyze magnesium hydride. Figure 4 The temperature-dependent hydrogenation curve of the modified magnesium hydride prepared in Comparative Example 1 shows that the initial hydrogenation temperature of the unmodified magnesium hydride is 315° C. The initial hydrogenation temperatures of different Ti4O7 contents and the initial hydrogenation temperatures of Ti4O7-7wt.%-MgH2 at different rotation speeds and different ball-to-material ratios are shown in Tables 1 and 2, respectively, as follows.

[0063] Table 1 is the statistical table of initial hydrogen desorption temperature at different Ti4O7 contents

[0064] <![CDATA[Ti4O7 / g]]> <![CDATA[MgH2 / g]]> Speed ​​(r / min) Ball to Material Ratio Initial hydrogen release temperature (℃) Example 1 0.03 0.97 400 160:1 291 Example 2 0.05 0.95 400 160:1 281 Example 3 0.07 0.93 400 160:1 241 Example 4 0.1 0.90 400 160:1 274 Example 5 0.01 0.99 400 160:1 310 Comparative Example 1 0 1 400 160:1 315

[0065] Table 2 Statistics of initial dehydrogenation temperature of Ti4O7-7wt.%-MgH2 at different rotation speeds and different ball-to-material ratios

[0066] <![CDATA[Ti4O7 / g]]> <![CDATA[MgH2 / g]]> Speed ​​(r / min) Ball to Material Ratio Initial hydrogen release temperature (℃) Example 3 0.07 0.93 400 160:1 241 Example 6 0.07 0.93 380 150:1 245 Example 7 0.07 0.93 350 155:1 248 Example 8 0.07 0.93 450 165:1 242 Example 9 0.07 0.93 700 150:1 244 Example 10 0.07 0.93 300 180:1 255

[0067] It can be seen from Table 1 and Table 2 that when the Ti4O7 content is too low, the initial dehydrogenation temperature of the composite material is higher because less catalyst cannot provide sufficient reactive sites for MgH2; when the Ti4O7 content is too high, the initial dehydrogenation temperature of the composite material will be higher because more catalysts hinder the reactive sites of MgH2. The final result shows that when the content of H is 7wt.%, the initial dehydrogenation temperature is the lowest, which is 241℃. The change of speed and ball-to-material ratio within a certain range has little effect on the initial dehydrogenation temperature of the composite material. When the speed is 400r / min and the ball-to-material ratio is 160:1, the initial dehydrogenation temperature of the composite material is the lowest, which is 241℃.

[0068] (2) Activation energy test

[0069] The isothermal hydrogen absorption of MgH2-7wt.%-Ti4O7 composite material was tested at three constant stable temperatures of 100°C, 150°C and 200°C, and the isothermal hydrogen absorption data of MgH2-7wt.%-Ti4O7 composite material were fitted using equation (1). α represents the reaction progress, and its value range is (0.2<α<0.8), t represents the reaction time, n represents the Avramiindex, and k represents the reaction rate constant; equation (2) is used to fit the activation energy, R represents the gas constant, T represents the reaction temperature, and K0 represents the Arrhenius constant.

[0070] Ln[-Ln(1-α)]=n Ln t+n Ln k (1)

[0071] Ea=-RT Ln(k / k0) (2)

[0072] from Figure 5 It can be seen that the activation energy of hydrogen absorption is 33.92±5.70 kJ / mol.

[0073] (3) Constant temperature hydrogen absorption performance test

[0074] During the constant temperature hydrogen absorption test, the sample is placed in a reactor in an argon environment glove box, the reactor is evacuated, and then the valve is closed. The hydrogen pressure of the hydrogen cylinder is set to a constant pressure of 50 bar, and the reactor is heated to a preset temperature. When the temperature is constant at the preset temperature, the reactor valve is opened, and the hydrogen absorption data is tested. Figure 6 The isothermal hydrogen absorption curve of the composite hydrogen storage material prepared in Example 3 of the present invention at different temperatures shows that at 250°C, the hydrogen absorption can reach 95% of the theoretical value (hydrogen absorption is 6.7wt.%) in just 30s, and the hydrogen absorption in 2min is 6.8wt.%, reaching 96% of the theoretical value, reaching the maximum hydrogen absorption; at 200°C, the hydrogen absorption in 15min is 6.55wt.%, reaching 93% of the theoretical value; at 150°C, the hydrogen absorption in 25min is 6.36wt.%, reaching 90% of the theoretical value; at 100°C, the final hydrogen absorption is 5.2wt.%, reaching 71.62% of the theoretical value. In addition, at 50°C, the hydrogen absorption time is 2h, and the hydrogen absorption is 1.7wt.%, reaching 24.05% of the theoretical value. The composite material has the advantage of low-temperature hydrogen absorption.

[0075] Figure 7This is a graph of the isothermal hydrogen absorption curve of the unmodified magnesium hydride at 250°C in Comparative Example 1 of the present invention. It can be seen from the figure that at 250°C, it takes about 25 minutes for the unmodified magnesium hydride to reach a stable hydrogen absorption state. Compared with the MgH2-7wt.%Ti4O7 composite material, it takes a longer time to reach a stable hydrogen absorption state. It can be seen that adding a catalyst can accelerate the hydrogen absorption rate, shorten the equipment insulation time, and reduce energy consumption.

[0076] The present invention loads Ti4O7 on the surface of MgH2, weakens the Mg-H ion bond energy, reduces the initial dehydrogenation temperature, provides a large number of active sites for Mg to absorb hydrogen, reduces the activation energy of hydrogen absorption, and accelerates the hydrogen absorption rate at high temperature.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A Ti4O7-MgH2 composite hydrogen storage material, characterized in that: The Ti4O7-MgH2 composite hydrogen storage material is prepared by loading Ti4O7 on the surface of MgH2, wherein the mass percentage of Ti4O7 is 1-10 wt%.

2. The Ti4O7-MgH2 composite hydrogen storage material according to claim 1, characterized in that: The Ti4O7 has oxygen vacancies, and the valence of Ti is +3 and +4.

3. The Ti4O7-MgH2 composite hydrogen storage material according to claim 1, characterized in that: The hydrogen absorption activation energy of the Ti4O7 / MgH2 composite hydrogen storage material is reduced to 33.92 KJ / mol.

4. The Ti4O7-MgH2 composite hydrogen storage material according to claim 1, characterized in that: The Ti4O7 / MgH2 composite hydrogen storage material absorbs 6.7 wt.% of hydrogen in 30 seconds at 250°C; the hydrogen absorption is saturated in 2 minutes, and the maximum hydrogen absorption is 6.8 wt.%.

5. The Ti4O7-MgH2 composite hydrogen storage material according to claim 1, characterized in that: The Ti4O7 / MgH2 composite hydrogen storage material can absorb hydrogen up to 1.7 wt.% at 50°C for 2 h.

6. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material according to claim 1, characterized in that: The steps are as follows: ball mill Ti4O7 and MgH2 in a hydrogen atmosphere to obtain.

7. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material according to claim 6, characterized in that: The mass of the Ti4O7 accounts for 1-10% of the total mass of Ti4O7 and MgH2.

8. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material according to claim 7, characterized in that: The ball-to-material ratio during the ball milling process is 150-180:

1.

9. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material according to claim 8, characterized in that: The rotation speed of the ball mill is 300-700 rpm / min.

10. The method for preparing the Ti4O7-MgH2 composite hydrogen storage material according to claim 9, characterized in that: The ball milling time is 3-6 h.

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