Magnesium-based hydrogen storage material with ni-based active substance supported by nb4n5 and preparation method and application thereof

Abstract

The application relates to a magnesium-based hydrogen storage material of Nb4N5 loaded Ni-based active substance and a preparation method and application thereof, and belongs to the hydrogen storage material field. The magnesium-based hydrogen storage material is prepared through the steps of dissolving, hydrothermal reaction, nitriding, stirring reaction, centrifugal washing, drying and mechanical ball milling, and takes MgH2 as a material basis, adds 3wt.%-15wt.% of a Ni(OH)2@Nb4N5 or NiO@Nb4N5 composite catalyst. Nb4N5 is used as a carrier to uniformly load Ni(OH)2 or NiO to form a composite catalyst. The magnesium-based hydrogen storage material has excellent hydrogen absorption and release performance, improves hydrogen storage capacity and kinetic performance, provides a new material selection for a solid-state hydrogen storage field, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials, and relates to magnesium-based hydrogen storage materials supported on Nb4N5 with Ni-based active materials, their preparation methods and applications. Background Technology

[0002] With the introduction of the "dual carbon" target, the development of the hydrogen energy industry has attracted much attention. Hydrogen storage and transportation technology is a key bottleneck to the large-scale and practical application of hydrogen energy. Magnesium-based solid hydrogen storage materials have broad development prospects due to their advantages such as high capacity, low price, and green environmental protection, but they still have limitations such as slow kinetics, thermodynamic instability, and poor cycle performance.

[0003] To effectively improve the hydrogen storage performance of MgH2, various methods have been proposed for modifying the MgH2 system, such as alloying, nano-sizing, doping catalysis, and composite formation. Among these, doping catalysis is a convenient and effective method. This invention aims to address the key issues of high hydrogen absorption and desorption temperatures, slow kinetics, and poor cycling performance of MgH2 by doping with a dual transition metal catalyst. Specifically, it seeks to achieve rapid hydrogen absorption and desorption kinetics at low temperatures while maintaining good cycling stability of the composite system.

[0004] Typically, the catalytic effect of single-metal elements has limitations. The synergistic catalytic effect of bimetallic elements can complement each other's advantages. However, the type of bimetallic element, its combination mode, and phase composition all have different influences on the synergistic catalytic effect. Transition metal nitrides, due to their stable chemical properties, do not cause capacity loss in the composite system and have good cycle stability, but their low-temperature hydrogen desorption performance is still relatively limited. The introduction of Ni has been shown to greatly improve the hydrogen storage performance of MgH2. Ni can form Mg2Ni / Mg2NiH4 during hydrogen adsorption and desorption, acting as a "hydrogen pump" to enable reversible hydrogen adsorption and desorption of MgH2 at lower temperatures. Furthermore, studies have shown that the synergistic catalysis of pre- and post-transition metals can give MgH2 excellent overall performance. Based on this, this invention proposes to introduce Ni-based active materials into the Nb4N5 transition metal nitride catalyst. Although Ni is a common catalyst element, there are currently no research reports on the catalytic modification of MgH2 using hydroxides. Due to the high reactivity of hydroxides, they can react simultaneously during the ball milling process to generate catalytically active substances, exhibiting excellent catalytic effects. At the same time, this simplifies the catalyst preparation process and saves costs.

[0005] CN114477082A discloses a nano-Ni-Nb-O-doped magnesium hydride hydrogen storage material. Nano-Ni-Nb-O possesses a multi-valence chemical environment and a "hydrogen pump" effect, effectively improving the hydrogen storage performance of MgH2. However, its structure is relatively simple, lacking a multi-level structure to further enhance the catalytic effect. The preparation method of nano-Ni-Nb-O involves a two-step solvothermal method and calcination, which are relatively complex and costly. The nano-Ni-Nb-O-doped magnesium hydride hydrogen storage material exhibits low cycle life and low hydrogen storage capacity retention. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a Ni(OH)₂-doped Mg / MgH₂ hydrogen storage material supported on Nb₄N₅, where Nb₄N₅ simultaneously functions as a support and catalyst. As a support, it possesses a stable structure and a large specific surface area, providing abundant nucleation sites for Ni(OH)₂ loading, resulting in fine and uniformly dispersed Ni(OH)₂. As a catalyst, it exhibits excellent catalytic activity and synergistically catalyzes the Ni-based active material on its surface. The synergistic catalytic effect of Ni(OH)₂ or NiO with Nb₄N₅ significantly improves the hydrogen absorption / desorption performance and cycle stability of the hydrogen storage material.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a magnesium-based hydrogen storage material supported on Nb4N5 with Ni-based active material, wherein the magnesium-based hydrogen storage material is composed of any compound selected from MgH2 and Ni(OH)2@Nb4N5 or NiO@Nb4N5;

[0009] Preferably, the magnesium-based hydrogen storage material comprises MgH2 and Ni(OH)2@Nb4N5 or NiO@Nb4N5 with a mass percentage of 3 wt.% to 15 wt.%, wherein the Nb4N5 surface is uniformly loaded with Ni(OH)2 or NiO to form a composite catalyst;

[0010] Furthermore, this invention provides a method for preparing a magnesium-based hydrogen storage material supported on Nb4N5 with Ni-based active material, the steps of which are as follows:

[0011] S1: Dissolve NbCl5 in anhydrous ethanol and stir until the solution is clear. Then add ammonia and stir the reaction. After centrifugation, the precipitate is obtained. The precipitate is dissolved in deionized water and placed in a forced-air drying oven for hydrothermal reaction. After centrifugation, the precipitate is obtained. The precipitate is washed with deionized water and freeze-dried to obtain Nb4N5 precursor.

[0012] S2: The Nb4N5 precursor prepared in step S1 is nitrided by temperature program, placed in a ceramic crucible, and calcined by ammonia gas in a tube furnace to obtain the Nb4N5 catalyst.

[0013] S3: Dissolve NiCl2·6H2O in deionized water to obtain solution 1. Stir and sonicate the Nb4N5 catalyst from step S2 with deionized water to obtain solution 2. Add solution 1 to solution 2 and stir the reaction in a water bath. Add ammonia to adjust the pH to 8-12. Wash the precipitate with deionized water and anhydrous ethanol by centrifugation and dry to obtain Ni(OH)2@Nb4N5 catalyst. Calcine the Ni(OH)2@Nb4N5 catalyst under an argon atmosphere to obtain NiO@Nb4N5 catalyst.

[0014] S4: The Ni(OH)2@Nb4N5 catalyst or NiO@Nb4N5 catalyst obtained in step S3 is mixed with MgH2 powder and mechanically ball-milled under an argon atmosphere to obtain the Ni(OH)2@Nb4N5-MgH2 magnesium-based hydrogen storage material;

[0015] Preferably, in step S1, the mass-to-volume ratio of NbCl5, anhydrous ethanol, and ammonia is 0.5–1:5–20:8–60 (g:mL:mL); the concentration of ammonia is 4–25%; the stirring reaction conditions are: stirring at a rate of 200–800 rpm for 1–10 h; and the hydrothermal reaction conditions are: reacting at 180–250 °C in the reactor for 12–36 h.

[0016] Preferably, the temperature-programmed nitriding parameters in step S2 are as follows: heating to 600℃~900℃ at a heating rate of 2~10℃ / min, and calcining for 2~8h;

[0017] Preferably, in step S3, the molar volume ratio of Nb4N5, NiCl2·6H2O, and deionized water is 1:1~5:50~150 (mol:mol:L); the stirring reaction conditions are: stirring at a rate of 200~800 rpm for 10~60 min; the water bath stirring reaction conditions are: stirring at a rate of 200~800 rpm in a water bath at 40℃~80℃ for 1~10 h; the centrifugation washing conditions are: centrifugation washing with deionized water / anhydrous ethanol at a speed of 3000~8000 rpm 3~5 times; and the drying conditions are: vacuum drying at 60~100℃ for 8~16 h.

[0018] Preferably, the mechanical ball mill uses stainless steel balls, argon as the grinding atmosphere, a ball-to-material ratio of 10-40:1, a grinding time of 5-12 hours, a grinding speed of 350-500 rpm, and intermittent ball milling in both forward and reverse directions: after each 5-30 minute grinding, the mill pauses for 5-30 minutes and then reverses the direction.

[0019] The application of the magnesium-based hydrogen storage material in solid-state hydrogen storage.

[0020] The beneficial effects of this invention are as follows:

[0021] On the one hand, using Nb4N5 as a catalyst, after ball milling with MgH2, it can be uniformly dispersed on the surface of the MgH2 matrix, becoming a stable catalytically active material that provides a large number of active sites for hydrogen dissociation and diffusion. On the other hand, loading Ni(OH)2 / NiO onto the surface of Nb4N5 to synergistically modify MgH2, the "hydrogen pump" effect combined with the "electron transfer" effect further improves the low-temperature hydrogen desorption performance of MgH2. At the same time, the addition of Ni effectively inhibits particle agglomeration during the cycle and improves the cycle stability of MgH2. Taking MgH2-Ni(OH)2@Nb4N5 as an example, the synergistic modification of MgH2 with Ni(OH)2 supported by Nb4N5 has the following advantages: (1) It has stable hydrogen storage cycle performance, and the hydrogen absorption capacity retention rate is as high as 95.35% after 90 cycles; (2) It improves the hydrogen release rate (at 300℃, the magnesium-based hydrogen storage material formed by synergistic modification of MgH2 with Ni(OH)2 supported by Nb4N5 releases 5.92wt.% of hydrogen in only 3 minutes, while pure MgH2 hardly releases any hydrogen); (3) The hydrogen absorption capacity was increased (by adding 6 wt.% Ni(OH)2@Nb4N5, MgH2 could rapidly absorb 4.70 wt.% hydrogen within 10 min at 150℃, and the hydrogen adsorption capacity could reach 5.25 wt.% after the time was extended to 30 min. As the temperature decreased, the composite material could still maintain a relatively fast hydrogen absorption rate. At 100℃, it could absorb 4.40 wt.% hydrogen within 30 min, while pure MgH2 required 60 min at 150℃ to adsorb only 0.59 wt.% hydrogen).

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0024] Figure 1 The image shows a SEM image of the Nb4N5 catalyst prepared in Example 1.

[0025] Figure 2 The TEM image of the Ni(OH)2@Nb4N5 catalyst prepared in Example 1 is shown below.

[0026] Figure 3The XRD pattern of the Ni(OH)2@Nb4N5 catalyst prepared in Example 1 is shown below.

[0027] Figure 4 Isothermal hydrogen release / absorption curves of magnesium-based hydrogen storage materials (MgH2-Ni(OH)2@Nb4N5 mixed powder) with different catalyst doping amounts prepared in Examples 1 and 2;

[0028] Figure 5 Figure 1 shows the isothermal hydrogen desorption curves of ball-milled MgH2 powder and magnesium-based hydrogen storage materials (MgH2-Ni(OH)2@Nb4N5 mixed powder, MgH2-Nb4N5 mixed powder, and MgH2-Ni(OH)2 mixed powder) prepared in Examples 1, 5, and 6. Figure 2b shows the hydrogen desorption curve at 200℃.

[0029] Figure 6 Isothermal hydrogen absorption curves of ball-milled MgH2 powder and magnesium-based hydrogen storage materials (MgH2-Ni(OH)2@Nb4N5 mixed powder, MgH2-Nb4N5 mixed powder, and MgH2-Ni(OH)2 mixed powder) prepared in Examples 1, 5, and 6;

[0030] Figure 7 The JMAK plots (a, c) and Arrhenius curves (b, d) of the ball-milled pure MgH2 sample and the MgH2-Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material prepared in Example 1 are shown.

[0031] Figure 8 The graph shows the cyclic hydrogen absorption and desorption performance of the magnesium-based hydrogen storage material (MgH2-Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0035] Example 1

[0036] A magnesium-based hydrogen storage material supported on Nb4N5 and synergistically modified with Ni(OH)2, and its preparation method are as follows:

[0037] Preparation of Ni(OH)₂@Nb₄N₅ catalyst: First, 1g of NbCl₅ was dissolved in 10ml of anhydrous ethanol and stirred for 10min. Then, 50ml of 4wt.% ammonia solution was slowly added to the above solution. After stirring for 2h, the mixture was centrifuged to obtain a precipitate, which was dissolved in 60ml of deionized water and transferred to a 100ml high-pressure reactor. The mixture was reacted at 200℃ for 24h. After the reaction was completed and cooled, the product was washed four times by centrifugation at 6000rpm with deionized water. The obtained product was freeze-dried to obtain the precursor. Then, temperature-programmed nitriding was performed. The above precursor sample was placed in a ceramic crucible and placed in a tube furnace. An ammonia atmosphere was turned on, and the temperature was raised to 750℃ at a rate of 10℃ / min and held for 4h to obtain Nb₄N₅ catalyst powder. Next, Ni(OH)2 loading was carried out. 1.19 g NiCl2·6H2O was dissolved in 50 ml of deionized water and stirred for 10 min to obtain a light green clear solution 1. 0.44 g of flower-shaped Nb4N5 was stirred and sonicated with 150 ml of deionized water for 30 min to obtain a uniform black solution 2. Solution 1 was added to solution 2 while stirring, and then ammonia was slowly added dropwise to adjust the pH to 9. The resulting solution was transferred to a water bath at 60 °C and stirred at 500 rpm for 5 h. After the reaction, the precipitate was centrifuged and washed 3 times with deionized water at 6000 rpm and washed once with anhydrous ethanol. Finally, the precipitate was placed in a vacuum drying oven and dried at 80 °C for 12 h to obtain the Ni(OH)2@Nb4N5 catalyst.

[0038] (2) Preparation of Ni(OH)2@Nb4N5-MgH2 composite material: 0.06g of the above-prepared Ni(OH)2@Nb4N5 powder was used as a catalyst and mixed with 0.94g of MgH2 powder in a high-purity argon atmosphere (the mass ratio of Ni(OH)2@Nb4N5 powder to MgH2 powder was 6:94). The mixture was mechanically ball-milled for 10h in an argon atmosphere to obtain Ni(OH)2@Nb4N5-MgH2 mixed powder (the ball-to-material ratio was 20:1, the ball milling speed was 400rpm, the ball milling jar was a 100mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm).

[0039] Figure 1 This is a SEM image of the flower-like Nb4N5 catalyst prepared in Example 1. From... Figure 1 It can be seen that the Nb4N5 catalyst prepared in Example 1 is a flower-like cluster of 2μm to 5μm.

[0040] Figure 2 The image shows the TEM spectrum of the Ni(OH)₂@Nb₄N₅ catalyst prepared in Example 1. Figure 2It can be seen that two-dimensional regular sheet-like Ni(OH)2 of 50-100 nm is uniformly loaded on the three-dimensional Nb4N5 catalyst framework.

[0041] Figure 3 The XRD pattern of the Ni(OH)₂@Nb₄N₅ catalyst prepared in Example 1 is shown below. Figure 2 It can be seen that the prepared Ni(OH)2@Nb4N5 catalyst is composed of Nb4N5 (74-0606) and Ni(OH)2 (73-1520).

[0042] The hydrogen storage performance of the MgH2-Ni(OH)2@Nb4N5 composite material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1 is studied as follows:

[0043] 50 mg of the Nb4N5-MgH2 composite material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1 was weighed in a glove box. The hydrogen desorption curves of the samples with temperature were tested using a PCTpro high-pressure gas adsorption instrument: isothermal hydrogen desorption curves at 300℃ and 250℃ with an initial hydrogen pressure of 0.01 MPa; isothermal hydrogen adsorption curves at 50℃, 100℃ and 150℃ with an initial hydrogen pressure of 3 MPa; and hydrogen adsorption and desorption curves after 90 cycles at 300℃.

[0044] To compare the performance of the magnesium-based hydrogen storage material (MgH2-6wt.%Nb4N5 mixed powder) prepared in Example 1, ball-milled MgH2 powder (prepared by ball milling 1g of commercial MgH2 for 10h under a high-purity argon atmosphere, wherein the ball-to-powder ratio was 20:1, the rotation speed was 400rpm, the ball milling jar was a 100mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm) was used as the control group. Figure 5 Isothermal hydrogen desorption curves for ball-milled MgH2 powder and the magnesium-based hydrogen storage material (MgH2-6wt.% Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1. Figure 5 (a) It can be seen that the magnesium-based hydrogen storage material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1 can completely release hydrogen within 15 minutes at 250°C, with a hydrogen release amount of 5.57wt.%; at 300°C, complete hydrogen release only takes 3 minutes, releasing 5.92wt.% of hydrogen gas, while pure MgH2 releases almost no hydrogen gas. It is worth mentioning that even at a low temperature of 200°C, the composite material can achieve complete hydrogen release within 155 minutes. Figure 5(b)). Compared with existing technologies, existing literature 1 (Sun, Weiqi, Zhang, Haohua, He, Qingjie et al. Monolithic nickel-doped molybdenum nitride improves hydrogenstorage properties of MgH2[J]. JOURNAL OF ALLOYS AND COMPOUNDS, 2025, 1010, DOI:10.1016 / j.jallcom.2024.177000.) indicates that MgH2-6Ni / Mo2N requires 5 minutes to completely release hydrogen even at 325℃, and when the temperature is reduced to 265℃, the hydrogen release time is as long as 30 minutes or more. Existing patent 1 (Jiangsu Jicui Antai Chuangming Advanced Energy Materials Research Institute Co., Ltd. A magnesium-based hydrogen storage material catalyzed by hexagonal boron nitride supported nano-nickel particles and its preparation method: CN202210837615.4 [P]. 2022-10-25.) shows that the MgH-5wt.%Ni@BN composite material did not achieve complete hydrogen release even after 16 minutes at 300℃, but when the temperature was reduced to 250℃, the hydrogen release time far exceeded 50 minutes. Therefore, it can be concluded that the MgH2-Ni(OH)2@Nb4N5 composite material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) has excellent low-temperature hydrogen release kinetics.

[0045] Figure 6 Isothermal hydrogen absorption curves are shown for ball-milled MgH2 powder and three magnesium-based composite hydrogen storage materials (MgH2-6wt.%Ni(OH)2@Nb4N5, MgH2-6wt.%Nb4N5, and MgH2-6wt.%Ni(OH)2 mixed powder). Figure 6As can be seen, the magnesium-based hydrogen storage material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1 can rapidly absorb 4.70wt.% hydrogen within 10 min at 150℃, and the hydrogen adsorption capacity can reach 5.25wt.% after the time is extended to 30 min. As the temperature decreases, the composite material still maintains a relatively fast hydrogen absorption rate, absorbing 4.40wt.% hydrogen within 30 min at 100℃. This represents a significant improvement compared to pure MgH2, which only adsorbs 0.59wt.% hydrogen in 60 min at 150℃. Compared with single transition metal catalysts (Nb4N5, Ni(OH)2), the Ni(OH)2@Nb4N5 catalyst has a better effect on improving the hydrogen absorption performance of MgH2. The hydrogen storage capacity of MgH2-6wt.%Ni(OH)2 composite material and MgH2-6wt.%Nb4N5 composite material after hydrogen absorption at 150℃ for 10 min is 4.65wt.% and 4.03wt.%, respectively. With the extension of time, the hydrogen absorption capacity of MgH2-6wt.%Ni(OH)2@Nb4N5 composite material continues to increase, and the gap gradually widens.

[0046] Therefore, it can be concluded that the hydrogen absorption kinetics of the magnesium-based hydrogen storage material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1 are significantly improved.

[0047] Figure 7 The JMAK plots (a, c) and Arrhenius curves (b, d) of the ball-milled pure MgH2 sample and the MgH2-Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material prepared in Example 1 are shown. By fitting the isothermal hydrogen desorption data points, the Ea(des) value of the MgH2-6wt%Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material was calculated to be 78.7 ± 3.2 kJ·mol⁻¹. -1 The value was significantly lower than the corresponding value calculated from ball-milled MgH2 (Ea(des) = 140.5 ± 18.3 kJ·mol⁻¹). -1 Therefore, the addition of Ni(OH)2@Nb4N5 catalyst reduced the Ea(des) of ball-milled MgH2 by approximately 44.0%, significantly improving the kinetic performance of MgH2 and enabling the MgH2-6wt%Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material to desorb H2 at low temperatures.

[0048] Figure 8 The graph shows the cyclic hydrogen absorption and desorption performance of the magnesium-based hydrogen storage material (MgH2-6wt.%Ni(OH)2@Nb4N5 mixed powder) prepared in Example 1. Figure 8It can be seen that after 90 cycles of hydrogen absorption and desorption, the hydrogen absorption capacity of the composite hydrogen storage material is still 5.74 wt.%, and the capacity retention rate is 95.35%, which shows excellent cycle stability and has a significant advantage compared with existing technologies.

[0049] Composite materials Number of cycles and temperature Capacity retention References <![CDATA[Mg-5wt.%NiF2@Ti3C2]]> 10 times, 350℃ 95.8％ 2 <![CDATA[MgH2+10wt%Ni-Nb / rGO]]> 20 times, 300℃ 93％ 3 <![CDATA[MgH2-8wt.%P-Ti(Nb)O2]]> 60 times, 248℃ 86.2％ 4 <![CDATA[MgH2-6wt.%Ni(OH)2@Nb4N5]]> 90 times, 300℃ 95.35％ This invention

[0050] Note: Existing literature 2 (Zhu, Xueqin, Yang, Minjian, Zheng, Chunnian, et al. Ti3C2 MXenesupported NiF2 nanoparticles synergistically catalyze efficient hydrogenstorage in Mg[J].INTERNATIONAL JOURNAL OF HYDROGEN ENERGY,2024,93,1343-1352.DOI:10.1016 / j.ijhydene.2024.09.133.) Existing literature 3 (Samuel Guemou, LiutingZhang, Shuai Li, et al.Exceptional catalytic effect of novel rGO-supported Ni-Nb nanocomposite on the hydrogen storage properties of MgH2[J].Journal ofMaterials Science & Technology, 2024, 172, (5): 83-93. DOI: 10.1016 / j.jmst.2023.07.016.) Existing literature 4 (Dan, Liang, Wang, Hui, Yang, Xiaobao, et al. Low-temperature solid-state hydrogen storage via efficiently catalyzed MgH2[J]. RENEWABLE ENERGY,2024,231,DOI:10.1016 / j.renene.2024.121009.)

[0051] Example 2

[0052] Two composite materials with different Ni(OH)2@Nb4N5-MgH2 doping amounts and their preparation methods are described. Unless otherwise specified, the steps are the same as in Example 1, except that 0.03g / 0.09g of Ni(OH)2@Nb4N5 catalyst is added during ball milling, and the mixture is mixed and ball-milled with 0.97g / 0.93g of MgH2 powder under a high-purity argon atmosphere.

[0053] To investigate the optimal doping quality of the Ni(OH)2@Nb4N5 catalyst, three composite materials of MgH2-xwt%Ni(OH)2@Nb4N5 (x = 3, 6, 9) obtained in Examples 1 and 2 were subjected to isothermal dehydrogenation (275℃) / hydrogen absorption (150℃) tests. The test methods were the same as in Example 1. The hydrogen release test results are as follows: Figure 4 As shown, at 275℃, the MgH2+3wt.%Ni(OH)2@Nb4N5 sample exhibited the slowest hydrogen desorption rate, with a hydrogen desorption amount of 2.54wt.% after 7 minutes. The MgH2+6wt.%Ni(OH)2@Nb4N5 and MgH2+9wt.%Ni(OH)2@Nb4N5 samples showed superior initial hydrogen desorption rates, comparable to each other, but after 7 minutes, a significant difference emerged in hydrogen desorption amounts, desorbing 5.71wt.% and 5.24wt.% of hydrogen, respectively. Furthermore, regarding hydrogen absorption kinetics, at 150℃ for 5 minutes, the hydrogen absorption amounts of the MgH2+x wt.%Ni(OH)2@Nb4N5 samples with x = 3, 6, and 9 were 3.94wt.%, 4.44wt.%, and 4.35wt.%, respectively. Overall, the optimal addition amount of Ni(OH)2@Nb4N5 catalyst is 6wt.%. Therefore, a sample doped with 6 wt.% Ni(OH)2@Nb4N5 catalyst was selected as a representative to further investigate the effect of Ni(OH)2@Nb4N5 catalyst on the hydrogen storage performance of MgH2.

[0054] Example 3

[0055] A magnesium-based hydrogen storage material supported on Nb4N5 and synergistically modified with Ni(OH)2, and its preparation method are as follows:

[0056] Preparation of Ni(OH)₂@Nb₄N₅ catalyst: First, 1g of NbCl₅ was dissolved in 10ml of anhydrous ethanol and stirred for 10min. Then, 50ml of 4wt.% ammonia solution was slowly added to the above solution. After stirring for 2h, the mixture was centrifuged to obtain a precipitate, which was dissolved in 60ml of deionized water and transferred to a 100ml high-pressure reactor. The mixture was reacted at 200℃ for 24h. After the reaction was completed and cooled, the product was washed four times by centrifugation at 6000rpm with deionized water. The obtained product was freeze-dried to obtain the precursor. Then, temperature-programmed nitriding was performed. The above precursor sample was placed in a ceramic crucible and placed in a tube furnace. An ammonia atmosphere was turned on, and the temperature was raised to 750℃ at a rate of 10℃ / min and held for 4h to obtain Nb₄N₅ catalyst powder. Next, Ni(OH)2 loading was carried out. 1.19 g NiCl2·6H2O was dissolved in 50 ml of deionized water and stirred for 10 min to obtain a light green clear solution 1. 0.44 g of flower-shaped Nb4N5 was stirred and sonicated with 150 ml of deionized water for 30 min to obtain a uniform black solution 2. Solution 1 was added to solution 2 while stirring, and then ammonia was slowly added dropwise to adjust the pH value to 9-10. The resulting solution was transferred to a water bath at 60 °C and stirred at 500 rpm for 5 h. After the reaction, the precipitate was centrifuged and washed 3 times with deionized water at 6000 rpm and washed once with anhydrous ethanol. Finally, the precipitate was placed in a vacuum drying oven and dried at 80 °C for 12 h to obtain the Ni(OH)2@Nb4N5 catalyst.

[0057] (2) Preparation of Ni(OH)2@Nb4N5-MgH2 composite material: 0.06g of the above-prepared Ni(OH)2@Nb4N5 powder was used as a catalyst and mixed with 0.91g of MgH2 powder in a high-purity argon atmosphere (the mass ratio of Ni(OH)2@Nb4N5 powder to MgH2 powder was 6:94). The mixture was mechanically ball-milled for 10h in an argon atmosphere to obtain Ni(OH)2@Nb4N5-MgH2 mixed powder (the ball-to-material ratio was 20:1, the ball milling speed was 400rpm, the ball milling jar was a 100mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm).

[0058] Example 4

[0059] A magnesium-based hydrogen storage material supported on Nb4N5 and synergistically modified with NiO, and its preparation method are as follows:

[0060] Preparation of NiO@Nb4N5 catalyst: First, 1g of NbCl5 was dissolved in 10ml of anhydrous ethanol and stirred for 10min. Then, 50ml of 4wt.% ammonia solution was slowly added to the above solution. After stirring for 2h, the precipitate was obtained by centrifugation. 60ml of deionized water was added to dissolve the precipitate, which was then transferred to a 100ml high-pressure reactor and reacted at 200℃ for 24h. After the reaction was completed and cooled, the precipitate was washed four times by centrifugation at 6000rpm with deionized water. The obtained product was freeze-dried to obtain the precursor. Then, temperature-programmed nitriding was performed. The above precursor sample was placed in a ceramic crucible and placed in a tube furnace. Ammonia atmosphere was turned on, and the temperature was raised to 750℃ at a rate of 10℃ / min and held for 4h to obtain Nb4N5 catalyst powder. Next, Ni(OH)2 loading was performed. 1.19 g of NiCl2·6H2O was dissolved in 50 ml of deionized water and stirred for 10 min to obtain a light green clear solution 1. 0.44 g of flower-shaped Nb4N5 was stirred and sonicated with 150 ml of deionized water for 30 min to obtain a uniform black solution 2. Solution 1 was added to solution 2 while stirring, and then ammonia was slowly added dropwise to adjust the pH to 9. The resulting solution was transferred to a water bath at 60 °C and stirred at 500 rpm for 5 h. After the reaction, the precipitate was centrifuged and washed three times with deionized water at 6000 rpm and once with anhydrous ethanol. Finally, the precipitate was placed in a vacuum drying oven and dried at 80 °C for 12 h to obtain Ni(OH)2@Nb4N5. Finally, Ni(OH)2@Nb4N5 was placed in a ceramic crucible and placed in a tube furnace. Argon atmosphere was turned on, and the temperature was raised to 300 °C at a rate of 10 °C / min and held for 2 h to obtain NiO@Nb4N5 catalyst powder.

[0061] (2) Preparation of NiO@Nb4N5-MgH2 composite material: 0.06g of the above-prepared NiO@Nb4N5 powder was used as a catalyst and mixed with 0.94g of MgH2 powder in a high-purity argon atmosphere (the mass ratio of NiO@Nb4N5 powder to MgH2 powder was 6:94). The mixture was mechanically ball-milled for 10h in an argon atmosphere to obtain NiO@Nb4N5-MgH2 mixed powder (the ball-to-material ratio was 20:1, the ball milling speed was 400rpm, the ball milling jar was a 100mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm).

[0062] Example 5

[0063] A Nb4N5-MgH2 composite material and its preparation method are disclosed. The steps not specifically described are the same as in Example 1, and Nb4N5 catalyst powder is prepared. The difference is that 0.06g of Nb4N5 catalyst is added during ball milling, and it is mixed and ball-milled with 0.94g of MgH2 powder under a high-purity argon atmosphere.

[0064] The obtained MgH2-6wt%Nb4N5 hydrogen storage material was subjected to isothermal dehydrogenation testing, using the same method as in Example 1. The hydrogen release test results are as follows: Figure 4 As shown in (a), at 300°C, it takes more than 7 minutes to release 6.00 wt.% of hydrogen. At 250°C, the hydrogen release is 5.4 wt.% within 30 minutes, and the release of hydrogen is still extremely slow even with extended time. The hydrogen absorption test results are as follows... Figure 5 As shown, 4.03 wt.% of hydrogen can be absorbed within 10 minutes at 150°C, but when the time is extended to 60 minutes, the amount of hydrogen absorbed is only 4.96 wt.%.

[0065] By comparing Example 5 and Example 1, it can be seen that the hydrogen release / absorption kinetics of the prepared MgH2-6wt.%Nb4N5 magnesium-based hydrogen storage material are not as good as those of the MgH2-6wt.%Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material, indicating that Example 1 has a better effect on improving the performance of magnesium hydride than Example 5.

[0066] Example 6

[0067] A Ni(OH)2-MgH2 composite material and its preparation method are disclosed. The steps not specifically described are the same as in Example 1, and Ni(OH)2 catalyst powder is prepared. The difference is that 0.06g of Ni(OH)2 catalyst is added during ball milling, and it is mixed and ball-milled with 0.94g of MgH2 powder under a high-purity argon atmosphere.

[0068] The obtained MgH2-6wt%Ni(OH)2 hydrogen storage material was subjected to isothermal dehydrogenation testing, using the same method as in Example 1. The hydrogen release test results are as follows: Figure 4 As shown in (a), at 300°C, complete hydrogen release requires more than 4 minutes, with a hydrogen release amount of 5.69 wt.%. The hydrogen absorption test results are as follows... Figure 5 As shown, 4.65 wt.% of hydrogen can be absorbed within 10 minutes at 150℃, and hydrogen absorption is slow over time thereafter, with the amount of hydrogen absorbed reaching 5.03 wt.% at 60 minutes.

[0069] Comparing Examples 6 and 1, it is evident that the hydrogen desorption kinetics of the prepared MgH2-6wt.%Ni(OH)2 magnesium-based hydrogen storage material are inferior to those of the MgH2-6wt.%Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material. While the hydrogen absorption kinetics are similar to those of the MgH2-6wt.%Ni(OH)2 magnesium-based hydrogen storage material in the first 10 minutes, the capacities after complete hydrogen desorption / absorption are both lower. Overall, the composite material of Example 1 exhibits better comprehensive hydrogen storage performance than that of Example 6.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A magnesium-based hydrogen storage material supported on Nb4N5 with Ni-based active material, characterized in that: The magnesium-based hydrogen storage material is composed of any compound selected from MgH2 and Ni(OH)2@Nb4N5 or NiO@Nb4N5; The magnesium-based hydrogen storage material includes MgH2 and Ni(OH)2@Nb4N5 or NiO@Nb4N5 with a mass percentage of 3wt.% to 15wt.%, wherein the Nb4N5 surface is uniformly loaded with Ni(OH)2 or NiO to form a composite catalyst. The preparation method of the magnesium-based hydrogen storage material supported on Nb4N5 with Ni-based active material comprises the following steps: S1: Dissolve NbCl5 in anhydrous ethanol and stir until the solution is clear. Then add ammonia and stir the reaction. After centrifugation, the precipitate is obtained. The precipitate is dissolved in deionized water and placed in a forced-air drying oven for hydrothermal reaction. After centrifugation, the precipitate is obtained. The precipitate is washed with deionized water and freeze-dried to obtain Nb4N5 precursor. The hydrothermal reaction conditions are: reaction at 180-250℃ in the reactor for 12-36 hours. S2: The Nb4N5 precursor prepared in step S1 is nitrided by temperature program, placed in a ceramic crucible, and calcined in a tube furnace by introducing ammonia gas to obtain the Nb4N5 catalyst. The specific temperature nitriding parameters are: heating to 600℃~900℃ at a heating rate of 2~10 ℃ / min, and calcining for 2~8 h. S3: Dissolve NiCl2•6H2O in deionized water to obtain solution 1. Stir and sonicate the Nb4N5 catalyst from step S2 with deionized water to obtain solution 2. Add solution 1 to solution 2 and stir the reaction in a water bath. Add ammonia to adjust the pH to 8-12. Wash the precipitate with deionized water and anhydrous ethanol by centrifugation and dry to obtain Ni(OH)2@Nb4N5 catalyst. Calcine the Ni(OH)2@Nb4N5 catalyst under an argon atmosphere to obtain NiO@Nb4N5 catalyst. S4: The Ni(OH)2@Nb4N5 catalyst or NiO@Nb4N5 catalyst obtained in step S3 is mixed with MgH2 powder and mechanically ball-milled under an argon atmosphere to obtain the Ni(OH)2@Nb4N5-MgH2 magnesium-based hydrogen storage material.

2. The magnesium-based hydrogen storage material with Nb4N5 supported on Ni-based active material according to claim 1, characterized in that, In step S1, the mass-to-volume ratio of NbCl5, anhydrous ethanol, and ammonia is 0.5–1:5–20:8–60 (g:mL:mL); the concentration of ammonia is 4–25%; and the stirring reaction conditions are: stirring at a rate of 200–800 rpm for 1–10 h.

3. The magnesium-based hydrogen storage material with Nb4N5 supported on Ni-based active material according to claim 1, characterized in that, In step S3, the molar volume ratio of Nb4N5, NiCl2•6H2O, and deionized water is 1:1~5:50~150 (mol:mol:L). The stirring reaction conditions are: stirring at 200~800 rpm for 10~60 min; the water bath stirring reaction conditions are: stirring at 200~800 rpm in a water bath at 40℃~80℃ for 1~10 h; the centrifugation washing conditions are: centrifuging and washing with deionized water / anhydrous ethanol at 3000~8000 rpm 3~5 times; and the drying conditions are: vacuum drying at 60~100℃ for 8~16 h.

4. The magnesium-based hydrogen storage material with Nb4N5 supported on Ni-based active material according to claim 1, characterized in that, The mechanical ball mill uses stainless steel balls, argon gas as the grinding atmosphere, a ball-to-material ratio of 10-40:1, a grinding time of 5-12 hours, a grinding speed of 350-500 rpm, and intermittent forward and reverse grinding: after each grinding session of 5-30 minutes, the grinding is paused for 5-30 minutes and the direction is reversed.

5. The application of the magnesium-based hydrogen storage material according to claim 1 in solid-state hydrogen storage.

Images