Catalyst for hydrogen storage material, its preparation method and application

Abstract

The application discloses a kind of catalysts for hydrogen storage material and its preparation method and application, belong to hydrogen storage material and its preparation technical field.The present application is to solve the problems such as high dehydrogenation temperature of existing magnesium-based solid hydrogen storage material and slow low-temperature kinetics.The present application is prepared by using nickel chloride hexahydrate, acetylacetone manganese, polyether P123, polyether P127, dopamine hydrochloride, 1,3,5-trimethylbenzene and ammonia as raw materials to obtain carbon as carrier wrapped with elemental Ni nanoparticle catalyst with a large number of edge dislocations, and is applied to Mg-based hydrogen storage material by ball milling method.The introduced dislocation has a dual role: not only directly accelerates the dissociation of H2 molecule, but also indirectly improves the activity of catalytic phase (Mg2NiH4 / Mg2Ni).The preparation process of the composite hydrogen storage material provided by the present application is simple and mature, and the raw materials are cheap and easy to obtain, only a small amount of MNC needs to be added to greatly improve the hydrogen storage performance of Mg, and it is convenient for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials and their preparation technology. Specifically, it relates to a catalyst for hydrogen storage materials, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, with its significant advantages of high energy density, high calorific value, and clean, pollution-free operation, has become a promising renewable energy source. However, hydrogen transportation faces numerous challenges, which is currently the main bottleneck hindering the wider application and in-depth development of hydrogen energy. Solid-state hydrogen storage technology, with its high density, high safety, and convenience, is widely recognized as a more promising option compared to compressed gaseous or liquid hydrogen storage.

[0003] Magnesium (Mg) is a promising hydrogen storage material due to its abundant natural reserves and high gravimetric hydrogen storage capacity (7.6 wt%). Direct catalytic hydrogenation of magnesium powder offers a more cost-effective alternative to the traditional method of repeatedly hydrogenating magnesium powder under high temperature and high hydrogen pressure conditions to obtain MgH2. Therefore, developing highly active and stable catalysts to improve the thermodynamic and kinetic properties of magnesium-based hydrogen storage materials is crucial for their commercial application. Defect engineering, nanostructuring, and doping modification are widely used to enhance the catalytic activity of catalysts. Among these methods, defect engineering has emerged as a highly promising modification approach in catalyst design. By modulating key properties such as the coordination environment, electronic structure, and geometry of active sites, it significantly enhances the activity and selectivity of catalytic materials. This strategy has demonstrated crucial roles in various catalytic reactions, including electrocatalytic carbon dioxide reduction (ECR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and photocatalytic reactions. Summary of the Invention

[0004] This invention aims to solve the technical problems of high hydrogen absorption and desorption temperatures and slow low-temperature kinetics in existing magnesium-based solid hydrogen storage materials, and provides a catalyst for hydrogen storage materials, its preparation method, and its application.

[0005] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0006] One objective of this invention is to provide a method for preparing a catalyst for hydrogen storage materials, the method comprising the following steps:

[0007] Step 1: Dissolve nickel chloride hexahydrate and manganese acetylacetonate (II) in a mixed solvent, ultrasonically disperse until uniform, add polyether P123, polyether P127, dopamine hydrochloride and 1,3,5-trimethylbenzene, stir evenly at room temperature, then add ammonia water, stir, centrifuge, filter, and dry to obtain precursor powder.

[0008] Step 2: Under an inert atmosphere, the precursor powder is calcined in stages to obtain a catalyst for hydrogen storage materials, named... MNC powder.

[0009] Further specifying, in step 1, the mixed solvent is prepared by water and anhydrous ethanol in a volume ratio of 1:1.

[0010] Further specifying, in step 1, the mass ratio of nickel chloride hexahydrate, manganese acetylacetonate (II), polyether P123, polyether P127 and dopamine hydrochloride is 2.37∶0.025∶0.25∶0.75∶1.5.

[0011] Further specifying, in step 1, the volume ratio of 1,3,5-trimethylbenzene, ammonia, and the mixed solvent is 1:1:25.

[0012] To further specify, in step 2, the inert gas is argon.

[0013] Further specifying, in step 2, the calcination process is as follows: hold at 350℃ for 2 hours, then raise the temperature to 800℃ and hold for 2 hours.

[0014] The second objective of this invention is to provide a hydrogen storage material catalyst MNC powder prepared by any of the above methods, wherein the hydrogen storage material catalyst MNC powder is a spherical particle with a diameter of 0.326±0.829µm.

[0015] A third objective of this invention is to provide a composite hydrogen storage material, which is prepared from MNC catalyst powder prepared by any of the above methods, or from the above-mentioned MNC catalyst powder and Mg powder as raw materials.

[0016] To be further specified, the Mg powder is spherical particles with a size of 325 mesh.

[0017] Furthermore, the proportion of MNC powder in the composite hydrogen storage material is 3 wt.% to 11 wt.%.

[0018] The fourth objective of this invention is to provide a method for preparing the above-mentioned composite hydrogen storage material, wherein the method comprises mechanically mixing MNC powder and Mg powder by intermittent ball milling under a protective atmosphere.

[0019] Further specifying, the intermittent ball milling method is as follows: 5 minutes of ball milling followed by a 10-minute rest, with a total ball milling time of 4 hours, a ball-to-material ratio of 40:1, and a ball milling speed of 400 rpm; the ball milling beads are zirconia beads with diameters of 0.3 cm and 0.5 cm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention prepares a catalyst (MNC) using nickel chloride hexahydrate, manganese acetylacetonate, polyether P123, polyether P127, dopamine hydrochloride, 1,3,5-trimethylbenzene, and ammonia as raw materials. This catalyst, supported by carbon and encapsulating elemental Ni nanoparticles with numerous edge dislocations, is applied to Mg-based hydrogen storage materials via ball milling. This process not only ensures more thorough grinding of the Mg powder but also uniformly mixes the MNC catalyst with the Mg powder.

[0022] The composite hydrogen storage material of this invention can absorb hydrogen at room temperature, with an apparent activation energy of 14.95 kJ / mol. Compared with BM-Mg (ball-milled Mg, Ea = 113.34 kJ / mol), its dehydrogenation activation energy is reduced by 40.43 kJ / mol. At 300 ºC, this material can release 6 wt.% H2 in just 7 minutes. Furthermore, it retains 95% of its capacity after 200 cycles.

[0023] Studies have shown that the introduced edge dislocations have a dual catalytic effect: on the one hand, they directly accelerate the dissociation of H2 molecules, and on the other hand, they indirectly enhance the activity of the catalytic phase (Mg2NiH4 / Mg2Ni). This invention reveals for the first time a novel mechanism of dislocation-catalyzed magnesium-based hydrogen storage, providing experimental and theoretical basis for solving the passivation problem of magnesium hydrogen storage materials, and laying the foundation for large-scale, low-cost applications.

[0024] Furthermore, the composite hydrogen storage material preparation process provided by this invention is simple and mature, and the raw materials are inexpensive and readily available. Only a small amount of MNC needs to be added to significantly improve the hydrogen storage performance of Mg, which is convenient for large-scale industrial production.

[0025] For a deeper understanding of the features and technical content of this invention, please refer to the accompanying detailed description and drawings. It should be noted that the drawings are provided for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0026] Figure 1 This is the X-ray diffraction pattern of the MNC prepared for Example 1;

[0027] Figure 2 A scanning electron microscope image of the MNC prepared in Example 1;

[0028] Figure 3 High-resolution transmission electron microscope image of the MNC prepared in Example 1;

[0029] Figure 4 X-ray photoelectron spectrum of the MNC prepared in Example 1;

[0030] Figure 5 Electron paramagnetic resonance image of the MNC prepared in Example 1;

[0031] Figure 6 The valence state diagram of Mn was tested using electron paramagnetic resonance (EPR) to obtain the MNC prepared in Example 1.

[0032] Figure 7 Comparison of isothermal hydrogen absorption curves of the composite hydrogen storage materials prepared in Example 1 and Comparative Examples 1-3;

[0033] Figure 8 Comparison of temperature-programmed hydrogen absorption curves of the composite hydrogen storage materials prepared in Example 2, Comparative Examples 1 and 4;

[0034] Figure 9 Comparison of isothermal hydrogen absorption curves of the composite hydrogen storage materials prepared in Example 2 and Comparative Examples 5-8;

[0035] Figure 10 Isothermal hydrogen absorption curves of the composite hydrogen storage material prepared in Example 2 at different temperatures;

[0036] Figure 11 Isothermal dehydrogenation curves of the composite hydrogen storage material prepared in Example 2 at different temperatures;

[0037] Figure 12 The cycling curve of the composite hydrogen storage material prepared in Example 2 after 200 cycles at 330 ºC;

[0038] Figure 13 This is a comparison diagram of the apparent activation energies of hydrogen absorption of the composite hydrogen storage materials prepared in Example 2 and Comparative Example 1;

[0039] Figure 14 This is a comparison diagram of the apparent activation energies of dehydrogenation of the composite hydrogen storage materials prepared in Example 2 and Comparative Example 1;

[0040] Figure 15 This is a high-resolution transmission electron microscope image of the composite hydrogen storage material prepared in Example 2 after hydrogen absorption. Detailed Implementation

[0041] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but should not be considered as limiting the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, all materials, reagents, methods, and instruments used are conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art. Furthermore, all solid and liquid reagents used are of analytical grade.

[0044] Example 1

[0045] The method for preparing MNC catalyst powder for hydrogen storage materials in this embodiment is as follows:

[0046] First, dissolve 0.01 mol of nickel chloride hexahydrate and 0.001 mol of manganese acetylacetonate (II) in a mixed solution of water and anhydrous ethanol (volume ratio 1:1) and sonicate for 10 min.

[0047] Next, 0.25g of polyether P123, 0.75g of polyether P127, 1.5g of dopamine hydrochloride and 4mL of 1,3,5-trimethylbenzene were added to the above mixed solution and stirred vigorously at room temperature.

[0048] Then, under magnetic stirring, 4 mL of ammonia water was added, and stirring was continued for 2 hours to obtain the MNC precursor solution.

[0049] Subsequently, the solid product was collected by centrifugation (8000 rpm, 1 min), washed three times each with anhydrous ethanol and deionized water, and then dried overnight in a 60°C oven to obtain MNC precursor powder.

[0050] Finally, in an argon atmosphere, the MNC precursor powder was calcined at 350°C for 2 hours at a rate of 3°C / min in a tube furnace, and then heated to 800°C for 2 hours at the same rate. The powder was then cooled to room temperature in the furnace to obtain MNC powder.

[0051] The microstructure of the MNC powder prepared in this embodiment was characterized. Figure 1 It can be seen that in addition to the diffraction peaks of Ni and C, the MNC catalyst also contains (NiO). 0.75 (MnO) 0.25 Phase. Scanning electron micrograph of MNC powder as shown. Figure 2 As shown, the MNC catalyst exhibits a rough, spherical surface. A high-resolution transmission electron microscope image of the powder is shown below. Figure 3 As shown, by Figure 3 It can be seen that Ni nanoparticles are encapsulated inside carbon, and at the same time, there are obvious dislocations inside the Ni lattice.

[0052] Furthermore, the X-ray photoelectron spectra of MNC powder with respect to Ni 2p and Mn 2p are as follows: Figure 4 As shown, Figure 4 This fully illustrates the bonding situation of the MNC catalyst. Besides existing in elemental form, Ni also exhibits Ni-O bonds, while Mn primarily bonds with O. This result fully verifies the presence of (NiO) in the MNC catalyst. 0.75 (MnO) 0.25 The existence of phases. Figure 5 and Figure 6 The image shows the electron paramagnetic resonance (EPR) spectrum of the MNC catalyst. Figure 5 This indicates that there are a large number of oxygen vacancies in the MNC catalyst, and Figure 6 This further proves that Mn exists in the MNC catalyst in the form of +2 oxidation state.

[0053] The method for preparing the composite hydrogen storage material Mg-9MNC in this embodiment is as follows:

[0054] Under argon atmosphere, 1g of Mg and 0.09g of MNC were weighed, and a certain amount of zirconium oxide beads were weighed according to the ball-to-material ratio of 40:1. The beads were placed in a ball mill jar and ball milled at 400rpm. The intermittent ball milling method was adopted, with each ball milling session lasting 5 minutes and a rest period of 10 minutes. The total ball milling time was 4 hours, and the composite hydrogen storage material was obtained, named Mg-9MNC.

[0055] Example 2

[0056] The difference between this comparative example and Example 1 is that the amount of MNC catalyst added is different. The specific steps are as follows:

[0057] Under an argon atmosphere, MNC powder and Mg powder were mixed at a mass ratio of 9:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-9MNC. Other steps and parameters were the same as in Example 1.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that no MNC catalyst was added; instead, only the Mg powder was ball-milled. The specific steps are as follows:

[0060] Under an argon atmosphere, 1g of Mg powder was added to a ball mill jar. A fixed amount of zirconia beads was weighed and placed in the ball mill jar at a ball-to-powder ratio of 40:1. The mixture was ball-milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest. The total milling time was 4 hours, yielding a composite hydrogen storage material named BM-Mg. Other steps and parameters were the same as in Example 1.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that no MNC catalyst was added; instead, an MC catalyst was added for ball milling. The specific synthesis steps of the MC catalyst are as follows:

[0063] First, add 0.001 mol manganese acetylacetone, 0.25 g polyether P123, 0.75 g polyether P127, 1.5 g dopamine hydrochloride and 4 mL of 1,3,5-trimethylbenzene to a mixed solution of water and anhydrous ethanol (volume ratio 1:1), and stir vigorously at room temperature until the solution is homogeneous.

[0064] Next, under magnetic stirring, 4 mL of ammonia water was added to the mixture, and stirring was continued for 2 hours to obtain the MC precursor solution.

[0065] Subsequently, the solid product was collected by centrifugation (8000 rpm, 1 min), washed three times each with anhydrous ethanol and deionized water, and then dried overnight in a 60°C oven to obtain MC precursor powder.

[0066] Finally, under an argon atmosphere, the MC precursor powder was first calcined at 350℃ for 2 hours, and then heated to 800℃ for 2 hours to finally obtain MC powder.

[0067] The steps of this comparative method for preparing the composite hydrogen storage material Mg-5MC are as follows:

[0068] Under an argon atmosphere, MC powder and Mg powder were mixed at a mass ratio of 5:100. A certain amount of zirconium oxide beads were weighed and placed in a ball mill jar at a ball milling speed of 400 rpm. The ball milling was carried out in an intermittent manner, with a 5-minute interval between milling and a 10-minute rest. The total milling time was 4 hours, and the composite hydrogen storage material was obtained and named Mg-5MC.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that no MNC catalyst was added; instead, an NC catalyst was added for ball milling. The specific synthesis steps of the NC catalyst are as follows:

[0071] First, add 0.01 mol nickel chloride hexahydrate, 0.25 g polyether P123, 0.75 g polyether P127, 1.5 g dopamine hydrochloride and 4 mL of 1,3,5-trimethylbenzene to a mixed solution of water and anhydrous ethanol (volume ratio 1:1), and stir vigorously at room temperature until the solution is homogeneous.

[0072] Next, under magnetic stirring, 4 mL of ammonia water was added to the mixture, and stirring was continued for 2 hours to obtain the NC precursor solution.

[0073] Subsequently, the solid product was collected by centrifugation (8000 rpm, 1 min), washed three times each with anhydrous ethanol and deionized water, and then dried overnight in a 60°C oven to obtain NC precursor powder.

[0074] Finally, under an argon atmosphere, the NC precursor powder was first calcined at 350°C for 2 hours, and then heated to 800°C for 2 hours to finally obtain NC powder.

[0075] The steps of this comparative method for preparing the composite hydrogen storage material Mg-5NC are as follows:

[0076] Under an argon atmosphere, NC powder and Mg powder were mixed at a mass ratio of 5:100. A certain amount of zirconium oxide beads were weighed and placed in a ball mill jar at a ball mill ratio of 40:1. The mixture was ball milled at a speed of 400 rpm using an intermittent ball milling method, with a 5-minute interval between milling and a 10-minute rest. The total ball milling time was 4 hours, resulting in a composite hydrogen storage material named Mg-5NC.

[0077] Comparative Example 4

[0078] The difference between this comparative example and Example 1 is that no MNC catalyst was added. Instead, MnO and NC catalysts with the same Mn and Ni content as the MNC catalyst were added. The specific steps are as follows:

[0079] Weigh out MnO and NC catalysts with the same Mn and Ni content as the MNC catalyst, grind them in a mortar and pestle to make them evenly mixed, and name them M / NC catalyst.

[0080] Under an argon atmosphere, M / NC powder and Mg powder were mixed at a mass ratio of 9:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-9M / NC. Other steps and parameters were the same as in Example 1.

[0081] Comparative Example 5

[0082] The difference between this comparative example and Example 1 is that the amount of MNC catalyst added is different. The specific steps are as follows:

[0083] Under an argon atmosphere, MNC powder and Mg powder were mixed at a mass ratio of 3:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-3MNC. Other steps and parameters were the same as in Example 1.

[0084] Comparative Example 6

[0085] The difference between this comparative example and Example 1 is that the amount of MNC catalyst added is different. The specific steps are as follows:

[0086] Under an argon atmosphere, MNC powder and Mg powder were mixed at a mass ratio of 5:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-5MNC. Other steps and parameters were the same as in Example 1.

[0087] Comparative Example 7

[0088] The difference between this comparative example and Example 1 is that the amount of MNC catalyst added is different. The specific steps are as follows:

[0089] Under an argon atmosphere, MNC powder and Mg powder were mixed at a mass ratio of 7:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was then ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-7MNC. Other steps and parameters were the same as in Example 1.

[0090] Comparative Example 8

[0091] The difference between this comparative example and Example 1 is that the amount of MNC catalyst added is different. The specific steps are as follows:

[0092] Under an argon atmosphere, MNC powder and Mg powder were mixed at a mass ratio of 11:100. A measured amount of zirconia beads were weighed and placed in a ball mill jar at a ball milling ratio of 40:1. The mixture was ball milled at 400 rpm using an intermittent milling method, with a 5-minute milling interval followed by a 10-minute rest, for a total milling time of 4 hours. The resulting composite hydrogen storage material was named Mg-11MNC. Other steps and parameters were the same as in Example 1.

[0093] The hydrogen storage performance of the composite hydrogen storage material Mg-5MNC prepared in Example 1, the composite hydrogen storage material BM-Mg prepared in Comparative Example 1, the composite hydrogen storage material Mg-5MC prepared in Comparative Example 2, and the composite hydrogen storage material Mg-5NC prepared in Comparative Example 3 was evaluated, and the evaluation results are shown below.

[0094] The isothermal hydrogen absorption curves of the composite hydrogen storage materials prepared in Example 1 and Comparative Examples 1-23 at 400 ºC and 3 MPa hydrogen pressure are compared as follows: Figure 7 As shown, by Figure 7 It can be seen that adding MNC catalyst can significantly improve the kinetic performance of Mg powder for hydrogen storage. At the same time, compared with Mg-5MNC material, the hydrogen storage capacity of Mg-5MNC is significantly improved. This result indicates that a small amount of Mn doping leads to the improvement of MNC catalytic activity, which can catalyze more passivated magnesium powder to participate in hydrogen storage.

[0095] The hydrogen storage performance of the composite hydrogen storage material Mg-9MNC prepared in Example 2, the composite hydrogen storage material BM-Mg prepared in Comparative Example 1, and the composite hydrogen storage material Mg-9M / NC prepared in Comparative Example 4 was evaluated, and the evaluation results are shown below.

[0096] The hydrogen absorption curves of the composite hydrogen storage materials prepared in Examples 2 and Comparative Examples 1 and 4, under programmed heating at a heating rate of 3 °C / min from room temperature (25 °C) to 400 °C at a hydrogen pressure of 3 MPa, are shown below. Figure 8 As shown, by Figure 8 It can be seen that the introduction of the catalyst significantly reduced the initial hydrogen absorption temperature of Mg powder. In particular, after adding the MNC catalyst, the Mg-9MNC composite material can begin to absorb hydrogen at room temperature. Compared with the Mg-9M / NC composite material, the initial hydrogen absorption temperature was reduced by approximately 45°C. This indicates that the improvement in hydrogen absorption performance is not directly due to the introduction of Mn, but rather due to the large number of lattice dislocations in Ni caused by the addition of Mn, which leads to the improvement in hydrogen absorption performance.

[0097] The hydrogen storage performance of the composite hydrogen storage materials Mg-9MNC prepared in Example 2, Mg-3MNC prepared in Comparative Example 5, Mg-5MNC prepared in Comparative Example 6, Mg-7MNC prepared in Comparative Example 7, and Mg-11MNC prepared in Comparative Example 8 was evaluated, and the evaluation results are shown below.

[0098] The isothermal hydrogen absorption curves of the composite hydrogen storage materials prepared in Example 2 and Comparative Examples 5-8 at 360 ºC and 5 MPa hydrogen pressure are compared as follows: Figure 9 As shown, by Figure 9 It can be seen that when the MNC catalyst addition amount is 9 wt.%, the hydrogen absorption rate is the fastest and the hydrogen storage capacity is the highest. Therefore, Mg-9MNC is the optimal hydrogen storage composite material. The isothermal hydrogen absorption curves of Mg-9MNC at medium and low temperatures are shown in the figure. Figure 10 As shown, Mg-9MNC can store 2.7 wt.% hydrogen gas within 2 hours at 50 ºC. The isothermal dehydrogenation curves of Mg-9MNC at different temperatures are shown in the figure. Figure 11 As shown, by Figure 11It can be seen that Mg-9MNC releases 6 wt.% hydrogen gas in just 7 minutes at 300 ºC. The cycling performance curve of the Mg-9MNC composite material at 330 ºC is shown in the figure below. Figure 12 As shown. By Figure 12 It can be seen that the capacity retention rate of Mg-9MNC after 200 cycles is 95%.

[0099] The hydrogen storage performance of the composite hydrogen storage material Mg-9MNC prepared in Example 2 and the composite hydrogen storage material BM-Mg prepared in Comparative Example 1 was further evaluated, and the evaluation results are shown below.

[0100] The comparison diagram of the hydrogen absorption activation energy of the composite hydrogen storage materials prepared in Example 2 and Comparative Example 1 is shown in the figure below. Figure 13 As shown, by Figure 13 It can be seen that the hydrogen absorption activation energy of the Mg-9MNC composite hydrogen storage material is 14.95 kJ / mol, while that of BM-Mg is 59.70 kJ / mol. A comparison of the dehydrogenation activation energies of the composite hydrogen storage materials prepared in Example 2 and Comparative Example 1 is shown in the figure below. Figure 14 As shown, by Figure 14 It can be seen that the dehydrogenation activation energy of the Mg-9MNC composite hydrogen storage material is 72.91 kJ / mol, while the dehydrogenation activation energy of BM-Mg is 113.34 kJ / mol.

[0101] To more intuitively elucidate the catalytic mechanism, high-resolution transmission electron microscopy analysis of the Mg-9MNC composite material samples after hydrogen absorption was performed, such as... Figure 15 As shown, a large number of dislocations still exist in the lattice of the Mg2NiH4 phase formed after hydrogen absorption. This indicates that after hydrogen absorption and desorption, the Mg2Ni / Mg2NiH4 phase of the Mg-9MNC composite material inherits the lattice dislocations from the Ni lattice, resulting in a stretching of the lattice spacing of Mg2Ni / Mg2NiH4. This facilitates the dissociation of hydrogen molecules into hydrogen atoms, thereby significantly improving the hydrogen storage performance of the Mg-9MNC material. Simultaneously, due to the "pinning" effect of oxygen vacancies, the dislocations can exist stably, enabling the Mg-9MNC material to maintain excellent capacity retention during cycling.

[0102] The specific embodiments of the present invention have been described in detail above. It should be noted that the present invention is not limited to the specific embodiments described above. Various modifications or alterations can be made by those skilled in the art without departing from the scope of protection defined by the claims, and all such modifications or alterations fall within the scope of the present invention.

Claims

1. A method for preparing a catalyst for hydrogen storage materials, characterized in that, Includes the following steps: Step 1: Dissolve nickel chloride hexahydrate and manganese acetylacetonate II in a mixed solvent, ultrasonically disperse until uniform, add polyether P123, polyether P127, dopamine hydrochloride and 1,3,5-trimethylbenzene, stir evenly at room temperature, then add ammonia water, stir, centrifuge, filter, and dry to obtain precursor powder; Step 2: Under an inert atmosphere, the precursor powder is calcined in stages to obtain a catalyst for hydrogen storage materials; wherein the mass ratio of nickel chloride hexahydrate, manganese acetylacetonate II, polyether P123, polyether P127 and dopamine hydrochloride is 2.37∶0.025∶0.25∶0.75∶1.

5. The catalyst is a carbon-supported, elemental Ni nanoparticle with a large number of edge dislocations.

2. The method according to claim 1, characterized in that, The mixed solvent is prepared by mixing water and anhydrous ethanol in a 1:1 volume ratio.

3. The method according to claim 1, characterized in that, The volume ratio of 1,3,5-trimethylbenzene, ammonia, and the mixed solvent is 1:1:

25.

4. The method according to claim 1, characterized in that, The inert gas is argon.

5. The method according to claim 1, characterized in that, The segmented calcination process involves first holding the temperature at 350℃ for 2 hours, then raising the temperature to 800℃ and holding it for another 2 hours.

6. A catalyst for hydrogen storage materials prepared by the method of any one of claims 1 to 5, wherein the catalyst is in the form of spherical particles with a diameter of 0.326 ± 0.829 µm.

7. A composite hydrogen storage material, characterized in that, It is prepared using the hydrogen storage material catalyst prepared by any one of claims 1-5 or the hydrogen storage material catalyst described in claim 6 and Mg powder as raw materials.

8. The composite hydrogen storage material according to claim 7, characterized in that, The catalyst used in the hydrogen storage material accounts for 3% to 11% of the composite hydrogen storage material, and the Mg powder is spherical particles with a size of 325 mesh.

9. A method for preparing the composite hydrogen storage material according to claim 7 or 8, characterized in that, Hydrogen storage material was obtained by mechanically mixing catalyst and Mg powder using intermittent ball milling under a protective atmosphere.

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