Magnesium-based hydrogen storage material of Nb4N5 loaded Ni-based active substance as well as preparation method and application of magnesium-based hydrogen storage material

Abstract

The invention relates to a magnesium-based hydrogen storage material of a Nb4N5-loaded Ni-based active substance as well as a preparation method and application of the magnesium-based hydrogen storage material, and belongs to the field of hydrogen storage materials. The preparation method comprises the following steps: by taking MgH2 as a material base, adding 3wt.%-15wt.% of Ni (OH) 2-coated Nb4N5 or NiO-coated Nb4N5 composite catalyst, dissolving, carrying out hydrothermal reaction, nitriding, carrying out stirring reaction, centrifugally washing, drying, carrying out mechanical ball milling and the like. Wherein the Nb4N5 is used as a carrier to uniformly load Ni (OH) 2 or NiO to form the composite catalyst. The magnesium-based hydrogen storage material has excellent hydrogen absorption and desorption performance, the hydrogen storage capacity and the dynamic performance are improved, a new material choice is provided for the field of solid hydrogen storage, and the magnesium-based hydrogen storage material has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen storage materials, and relates to a magnesium-based hydrogen storage material containing Nb4N5 loaded with a Ni-based active substance, and a preparation method and application thereof. Background Art

[0002] With the proposed "dual carbon" goals, the development of the hydrogen energy industry has attracted considerable attention. Hydrogen storage and transportation technology is a key bottleneck in achieving the scale and practical application of hydrogen energy. Magnesium-based solid-state hydrogen storage materials offer broad development prospects due to their high capacity, low price, and environmental friendliness. However, they are still limited by slow kinetics, excessive thermodynamic stability, and poor cycling performance.

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

[0004] Generally, the catalytic effect of a single metal element is limited, and the synergistic catalytic effect of a bimetallic element can make the two complement each other's advantages, but the type, combination mode, and physical phase results of the bimetallic element all have different influence rules on the synergistic catalytic effect. Transition metal nitrides, due to their stable chemical properties, will not cause capacity loss to the composite system and have good cyclic stability, but their low-temperature hydrogen release performance is still relatively limited. The introduction of Ni has been shown to have a great effect on the improvement of MgH2 hydrogen storage performance. It can form Mg2Ni / Mg2NiH4 during the hydrogen absorption and desorption process, play the role of a "hydrogen pump", and allow MgH2 to achieve reversible hydrogen absorption and desorption under relatively low temperature conditions. At the same time, studies have shown that the synergistic catalysis of the front and rear transition metals can enable MgH2 to obtain excellent comprehensive performance. Based on this, the present invention decides to introduce a Ni-based active material on the basis of the transition metal nitride Nb4N5 catalyst. Although Ni is a common catalyst element, there are currently no reports on the catalytic modification of MgH2 with hydroxide. Due to the high reactivity of hydroxide, it can react synchronously during the ball milling process to generate catalytically active substances, which has excellent catalytic effects and makes the catalyst preparation process simpler, saving costs.

[0005] CN114477082A discloses a hydrogen storage material doped with nano-Ni-Nb-O magnesium hydride. Nano-Ni-Nb-O has a multivalent chemical environment and a "hydrogen pump" effect, which can effectively improve the hydrogen storage performance of MgH2. However, its structure is relatively simple and lacks a multi-layer structure to further enhance the catalytic effect. The preparation method of nano-Ni-Nb-O is a relatively complex two-step solvent thermal method and calcination method, and the preparation process is relatively expensive. Nano-Ni-Nb-O doped with magnesium hydride has low cycle times and low hydrogen storage capacity retention rate. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a Nb4N5-loaded Ni(OH)2-doped catalytic Mg / MgH2 hydrogen storage material, in which Nb4N5 serves as both a carrier and a catalyst. As a carrier, it has a stable structure and a large specific surface area, providing abundant nucleation sites for the loading of Ni(OH)2, making the loaded Ni(OH)2 small and evenly dispersed. As a catalyst, it has excellent catalytic activity itself, producing a synergistic catalytic effect with the Ni-based active material on the surface. The synergistic catalytic effect of Ni(OH)2 or NiO and Nb4N5 significantly improves the hydrogen absorption and desorption performance and cyclic stability of the hydrogen storage material.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a magnesium-based hydrogen storage material in which Nb4N5 is loaded with a Ni-based active substance, wherein the magnesium-based hydrogen storage material is composed of MgH2 and any one of Ni(OH)2@Nb4N5 or NiO@Nb4N5;

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

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

[0011] S1: Dissolve NbCl5 in anhydrous ethanol and stir until the solution is clear. Then add ammonia water, stir and react, and centrifuge to obtain a precipitate. Dissolve the precipitate in deionized water and place it in a blast drying oven for hydrothermal reaction. Centrifuge to obtain a precipitate, wash it with deionized water, and freeze-dry it to obtain a Nb4N5 precursor.

[0012] S2: The Nb4N5 precursor prepared in step S1 is subjected to temperature-programmed nitridation, placed in a ceramic crucible, and calcined in a tube furnace by introducing ammonia gas to obtain a Nb4N5 catalyst;

[0013] S3: dissolving NiCl2·6H2O in deionized water to obtain solution 1, stirring the Nb4N5 catalyst prepared in step S2 with deionized water and ultrasonically obtaining solution 2, adding solution 1 to solution 2, stirring and reacting in a water bath, adding ammonia water to adjust the pH to 8-12, washing the precipitate with deionized water and anhydrous ethanol by centrifugation, and drying to obtain a Ni(OH)2@Nb4N5 catalyst, and calcining the Ni(OH)2@Nb4N5 catalyst under an argon atmosphere to obtain a 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 volume ratio of NbCl5, anhydrous ethanol, and aqueous ammonia is: 0.5-1:5-20:8-60, g:mL:mL; the concentration of aqueous ammonia is 4-25%, the stirring reaction conditions are: stirring the reaction at a rate of 200-800 rpm for 1-10 hours, and the hydrothermal reaction conditions are: reacting at 180-250°C in a reactor for 12-36 hours;

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

[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 minutes; the stirring reaction conditions in a water bath are: stirring at a rate of 200-800 rpm in a water bath at 40°C-80°C for 1-10 hours; the centrifugal washing conditions are: centrifugal washing with deionized water / anhydrous ethanol at a speed of 3000-8000 rpm for 3-5 times; the drying conditions are: vacuum drying at 60-100°C for 8-16 hours;

[0018] Preferably, the mechanical ball mill uses stainless steel balls, uses argon as the ball milling atmosphere, has a ball-to-material ratio of 10 to 40:1, a ball milling time of 5 to 12 hours, a ball milling speed of 350 rpm to 500 rpm, and intermittent ball milling in forward and reverse rotations: after each 5 to 30 minutes of ball milling, pause for 5 to 30 minutes and reverse the direction once;

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

[0020] The beneficial effects of the present invention are:

[0021] On the one hand, Nb4N5 is used as a catalyst. After composite ball milling with MgH2, it can be uniformly dispersed on the surface of the MgH2 matrix to become a stable catalytically active substance, providing a large number of active sites for the dissociation and diffusion of hydrogen; on the other hand, Ni(OH)2 / NiO is loaded on the surface of Nb4N5 to synergistically modify MgH2. The "hydrogen pump" effect and the "electron transfer" effect further enhance the low-temperature hydrogen desorption performance of MgH2. At the same time, the addition of Ni effectively inhibits the agglomeration of particles during the cycle and improves the cyclic stability of MgH2. Taking MgH2-Ni(OH)2@Nb4N5 as an example, the synergistic modification of MgH2 with Ni(OH)2 loaded on Nb4N5 has the following advantages: (1) stable hydrogen storage cycle performance, with a hydrogen absorption capacity retention rate of up to 95.35% after 90 cycles; (2) improved hydrogen release rate (at 300°C, the magnesium-based hydrogen storage material formed by the synergistic modification of MgH2 with Ni(OH)2 loaded on Nb4N5 only takes 3 minutes to release 5.92 wt.% of hydrogen, while pure MgH2 almost does not release hydrogen); (3) The hydrogen absorption capacity is increased (by adding 6wt.% Ni(OH)2@Nb4N5, MgH2 can quickly absorb 4.70wt.% of hydrogen within 10 minutes at 150°C, and the hydrogen adsorption capacity can reach 5.25wt.% when the time is extended to 30 minutes. As the temperature decreases, the composite material can still maintain a relatively fast hydrogen absorption rate. At 100°C, it can absorb 4.40wt.% of hydrogen within 30 minutes, while pure MgH2 only needs 60 minutes at 150°C to adsorb 0.59wt.% of hydrogen).

[0022] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0024] Figure 1 This is a SEM image of the Nb4N5 catalyst prepared in Example 1;

[0025] Figure 2 TEM spectrum of the Ni(OH)2@Nb4N5 catalyst prepared in Example 1;

[0026] Figure 3This is the XRD pattern of the Ni(OH)2@Nb4N5 catalyst prepared in Example 1;

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

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

[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, MgH2-Ni(OH)2 mixed powder) prepared in Example 1, Example 5, and Example 6;

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

[0031] Figure 8 This is a diagram of 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 DESCRIPTION

[0032] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0034] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships 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 direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] Example 1

[0036] A magnesium-based hydrogen storage material synergistically modified by Nb4N5 loading Ni(OH)2 and a preparation method thereof, the specific preparation method is as follows:

[0037] Preparation of Ni(OH)2@Nb4N5 catalyst: First, dissolve 1g NbCl5 in 10ml of anhydrous ethanol and stir for 10 minutes. Then, slowly add 50ml of 4wt.% ammonia water to the above solution, stir and react for 2h, then centrifuge to obtain a precipitate, add 60ml of deionized water to dissolve it, transfer it to a 100ml high-pressure reactor and react at 200℃ for 24h. After the reaction is completed and cooled, centrifuge and wash it four times with deionized water at a speed of 6000rpm. The resulting product is freeze-dried to obtain a precursor. Then, a temperature-programmed nitridation is performed. The above precursor sample is placed in a ceramic crucible, placed in a tube furnace, connected to an ammonia atmosphere, and heated to 750℃ at a rate of 10℃ / min and kept warm for 4h to obtain Nb4N5 catalyst powder. Next, Ni(OH)2 was loaded. 1.19g NiCl2·6H2O was dissolved in 50ml deionized water and stirred for 10min to obtain a light green clear solution 1. 0.44g flower-shaped Nb4N5 was stirred and ultrasonically mixed with 150ml deionized water for 30min to obtain a uniform black solution 2. Solution 1 was added to solution 2 with stirring, and then ammonia was slowly added dropwise to adjust the pH value to 9. The resulting solution was transferred to a 60°C water bath and stirred at 500rpm for 5h. After the reaction, the resulting precipitate was centrifuged and washed three times with deionized water at 6000rpm and once with anhydrous ethanol. Finally, the precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain the Ni(OH)2@Nb4N5 catalyst.

[0038] (2) Preparation of Ni(OH)2@Nb4N5-MgH2 composite material: 0.06 g of the prepared Ni(OH)2@Nb4N5 powder was used as a catalyst and mixed with 0.94 g 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 10 h 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 400 rpm, the ball milling jar was a 100 mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8 mm and 6 mm).

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

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

[0041] Figure 3 The XRD pattern of the Ni(OH)2@Nb4N5 catalyst prepared in Example 1 is shown in FIG. 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 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, and the temperature-dependent hydrogen desorption curve of the sample was tested using a PCTpro high-pressure gas adsorption instrument: isothermal hydrogen desorption curve at an initial hydrogen pressure of 0.01 MPa at 300°C and 250°C; isothermal hydrogen absorption curve at an initial hydrogen pressure of 3 MPa at 50°C, 100°C and 150°C; and 90-cycle hydrogen absorption and desorption curve at 300°C.

[0044] In order to compare the performance of the magnesium-based hydrogen storage material (MgH2-6wt.% Nb4N5 mixed powder) prepared in Example 1, ball-milled MgH2 powder (1g of commercial MgH2 was ball-milled for 10h in a high-purity argon atmosphere to prepare ball-milled MgH2 powder, wherein the ball-to-material ratio was 20:1, the rotation speed was 400rpm, the ball mill used was a stainless steel mill with a volume of 100mL, and the grinding balls were stainless steel grinding balls with diameters of 8mm and 6mm) was used as a control group. Figure 5 The isothermal hydrogen release curves of the 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 achieve complete hydrogen release within 15 minutes at 250℃, with a hydrogen release rate of 5.57wt.%; at 300℃, complete hydrogen release takes only 3 minutes, releasing 5.92wt.% of hydrogen, while pure MgH2 hardly releases hydrogen. It is worth mentioning that even at a low temperature of 200℃, the composite material can achieve complete hydrogen release within 155 minutes ( Figure 5Compared with the prior art, in the existing literature 1 (Sun, Weiqi, Zhang, Haohua, He, Qingjie, et al. Monolithic nickel-doped molybdenum nitride improves hydrogen storage properties of MgH2[J]. JOURNAL OF ALLOYS AND COMPOUNDS, 2025, 1010, DOI: 10.1016 / j.jallcom.2024.177000.), MgH2-6Ni / Mo2N requires 5 minutes to fully dehydrogenate even at 325°C. When the temperature is reduced to 265°C, the dehydrogenation time is as long as more than 30 minutes. 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-loaded nano-nickel particles and its preparation method: CN202210837615.4 [P]. 2022-10-25.) shows that the MgH2-5wt.%Ni@BN composite material does not completely release hydrogen even after 16 minutes at 300°C. When the temperature is reduced to 250°C, the hydrogen release time far exceeds 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 desorption kinetics.

[0045] Figure 6 The isothermal hydrogen absorption curves of ball-milled MgH2 powder and three magnesium-based composite hydrogen storage materials (MgH2-6wt.%Ni(OH)2@Nb4N5, MgH2-6wt.%Nb4N5, 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.% of hydrogen within 10 minutes at 150°C. After 30 minutes, the hydrogen adsorption amount reaches 5.25wt.%. As the temperature decreases, the composite material maintains a relatively fast hydrogen absorption rate, absorbing 4.40wt.% of hydrogen within 30 minutes at 100°C. This is a significant improvement over pure MgH2, which only absorbs 0.59wt.% of hydrogen in 60 minutes at 150°C. Compared with single transition metal catalysts (Nb4N5, Ni(OH)2), Ni(OH)2@Nb4N5 catalyst has a better effect on improving the hydrogen absorption performance of MgH2. The hydrogen storage capacities of MgH2-6wt.% Ni(OH)2 composite material and MgH2-6wt.% Nb4N5 composite material after hydrogen absorption at 150°C for 10 minutes are 4.65wt.% and 4.03wt.%, respectively. As time goes by, the hydrogen absorption capacity of MgH2-6wt.% Ni(OH)2@Nb4N5 composite material continues to increase, and the gap gradually widens.

[0046] 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 is 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. 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 , which is significantly lower than the corresponding value calculated by ball-milling MgH2 (Ea(des)=140.5±18.3kJ·mol -1 Therefore, the addition of Ni(OH)2@Nb4N5 catalyst reduced the Ea(des) of ball-milled MgH2 by about 44.0%, significantly improving the kinetic properties 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 This is a graph showing 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 5.74wt.%, and the capacity retention rate is 95.35%, showing excellent cycle stability, which has great advantages compared with the existing technology.

[0049] Composite materials Cycle times and temperature Capacity retention rate 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％ The present 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, the steps not otherwise specified are the same as those in Example 1, except that: 0.03g / 0.09g Ni(OH)2@Nb4N5 catalyst is added when ball milling the material, and the mixture is mixed with 0.97g / 0.93g MgH2 powder and ball milled in a high-purity argon atmosphere.

[0053] In order to explore the optimal doping quality of Ni(OH)2@Nb4N5 catalyst, three groups of MgH2-xwt%Ni(OH)2@Nb4N5 (x=3, 6, 9) composite materials obtained in Example 1 and Example 2 were subjected to isothermal dehydrogenation (275°C) / hydrogen absorption (150°C) tests. The test method was the same as that in Example 1. The dehydrogenation test results are shown in Figure 2. Figure 4 As shown, at 275°C, the MgH2 + 3wt.% Ni(OH)2@Nb4N5 sample exhibited the slowest hydrogen desorption rate, releasing 2.54wt.% hydrogen after 7 minutes. The MgH2 + 6wt.% Ni(OH)2@Nb4N5 and MgH2 + 9wt.% Ni(OH)2@Nb4N5 samples exhibited comparable initial hydrogen desorption rates, but after 7 minutes, a significant difference in hydrogen desorption occurred, with 5.71wt.% and 5.24wt.% hydrogen desorbed, respectively. Furthermore, regarding hydrogen absorption kinetics, after 5 minutes at 150°C, the MgH2 + xwt.% Ni(OH)2@Nb4N5 samples with x=3, 6, and 9 exhibited hydrogen absorption capacities of 3.94wt.%, 4.44wt.%, and 4.35wt.%, respectively. Overall, the optimal Ni(OH)2@Nb4N5 catalyst addition level is 6wt.%. Therefore, the sample doped with 6 wt.% Ni(OH)2@Nb4N5 catalyst was selected as a representative to further study 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 synergistically modified by Nb4N5 loading Ni(OH)2 and a preparation method thereof, the specific preparation method is as follows:

[0056] Preparation of Ni(OH)2@Nb4N5 catalyst: First, dissolve 1g NbCl5 in 10ml of anhydrous ethanol and stir for 10 minutes. Then, slowly add 50ml of 4wt.% ammonia water to the above solution, stir and react for 2h, then centrifuge to obtain a precipitate, add 60ml of deionized water to dissolve it, transfer it to a 100ml high-pressure reactor and react at 200℃ for 24h. After the reaction is completed and cooled, centrifuge and wash it four times with deionized water at a speed of 6000rpm. The resulting product is freeze-dried to obtain a precursor. Then, a temperature-programmed nitridation is performed. The above precursor sample is placed in a ceramic crucible, placed in a tube furnace, connected to an ammonia atmosphere, and heated to 750℃ at a rate of 10℃ / min and kept warm for 4h to obtain Nb4N5 catalyst powder. Next, Ni(OH)2 was loaded. 1.19g NiCl2·6H2O was dissolved in 50ml deionized water and stirred for 10min to obtain a light green clear solution 1. 0.44g flower-shaped Nb4N5 was stirred and ultrasonically mixed with 150ml deionized water for 30min to obtain a uniform black solution 2. Solution 1 was added to solution 2 with stirring, and then ammonia was slowly added dropwise to adjust the pH value to 9-10. The resulting solution was transferred to a 60°C water bath and stirred at 500rpm for 5h. After the reaction, the resulting precipitate was centrifuged and washed three times with deionized water at 6000rpm and once with anhydrous ethanol. Finally, the precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain the Ni(OH)2@Nb4N5 catalyst.

[0057] (2) Preparation of Ni(OH)2@Nb4N5-MgH2 composite material: 0.06 g of the prepared Ni(OH)2@Nb4N5 powder was used as a catalyst and mixed with 0.91 g 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 10 h 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 400 rpm, the ball milling jar was a 100 mL stainless steel jar, and the grinding balls were stainless steel grinding balls with diameters of 8 mm and 6 mm).

[0058] Example 4

[0059] A Nb4N5 loaded NiO synergistically modified magnesium-based hydrogen storage material and a preparation method thereof, the specific preparation method is as follows:

[0060] Preparation of NiO@Nb4N5 catalyst: First, 1g NbCl5 was dissolved in 10ml of anhydrous ethanol and stirred for 10 minutes. Then, 50ml of 4wt.% ammonia water was slowly added to the above solution. After stirring for 2 hours, the solution was centrifuged to obtain a precipitate. 60ml of deionized water was added to dissolve the precipitate, which was transferred to a 100ml autoclave and reacted at 200°C for 24 hours. After cooling, the product was washed four times with deionized water by centrifugation at 6000rpm. The resulting product was freeze-dried to obtain the precursor. The precursor was then subjected to temperature-programmed nitridation. The above precursor sample was placed in a ceramic crucible, placed in a tube furnace, connected to an ammonia atmosphere, and heated at a rate of 10°C / min to 750°C and maintained for 4 hours to obtain Nb4N5 catalyst powder. Next, Ni(OH)2 was loaded. 1.19 g NiCl2·6H2O was dissolved in 50 ml deionized water and stirred for 10 min to obtain a light green clear solution 1. 0.44 g flower-shaped Nb4N5 was stirred with 150 ml deionized water and ultrasonically stirred for 30 min to obtain a uniform black solution 2. Solution 1 was added to solution 2 with stirring, and then ammonia was slowly added dropwise to adjust the pH value to 9. The resulting solution was transferred to a 60°C water bath and stirred at 500 rpm for 5 h. After the reaction, the resulting 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, the Ni(OH)2@Nb4N5 was placed in a ceramic crucible, placed in a tube furnace, connected to an argon atmosphere, and heated to 300°C at a rate of 10°C / min and maintained for 2 h to obtain NiO@Nb4N5 catalyst powder.

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

[0062] Example 5

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

[0064] The obtained MgH2-6wt% Nb4N5 hydrogen storage material was subjected to isothermal dehydrogenation test. The test method was the same as that in Example 1. The dehydrogenation test results are shown in FIG. 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 amount of hydrogen released within 30 minutes is 5.4 wt.%, and the hydrogen release is still very slow when the time is extended. The hydrogen absorption test results are as follows Figure 5 As shown, 4.03 wt.% of hydrogen can be absorbed within 10 min at 150°C, and the amount of hydrogen absorbed is only 4.96 wt.% when the time is extended to 60 min.

[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 improvement effect on the performance of magnesium hydride than Example 5.

[0066] Example 6

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

[0068] The obtained MgH2-6wt% Ni(OH)2 hydrogen storage material was subjected to isothermal dehydrogenation test. The test method was the same as that in Example 1. The dehydrogenation test results were as follows: Figure 4 As shown in (a), at 300 ° C, it takes more than 4 minutes to achieve complete hydrogen release, and the amount of hydrogen released is 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 min at 150°C, and then hydrogen is absorbed slowly with time, and the hydrogen absorption amount is 5.03 wt.% after 60 min.

[0069] By comparing Example 6 with Example 1, it can be seen that the hydrogen desorption kinetics of the prepared MgH2-6wt.%Ni(OH)2 magnesium-based hydrogen storage material are not as good as those of the MgH2-6wt.%Ni(OH)2@Nb4N5 magnesium-based hydrogen storage material. The hydrogen absorption kinetics in the first 10 minutes are similar to those of the MgH2-6wt.%Ni(OH)2 magnesium-based hydrogen storage material, but the capacity after complete hydrogen desorption / absorption is lower. Overall, the comprehensive hydrogen storage performance of the composite material of Example 1 is better 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 limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. Magnesium-based hydrogen storage material with Nb4N5 loaded with Ni-based active material, characterized by: The magnesium-based hydrogen storage material consists of MgH2 and any one of Ni(OH)2@Nb4N5 and NiO@Nb4N5.

2. A magnesium-based hydrogen storage material according to claim 1, characterized in that: The magnesium-based hydrogen storage material includes MgH2 and 3wt.% to 15wt.% of Ni(OH)2@Nb4N5 or NiO@Nb4N5, and the surface of the Nb4N5 is uniformly loaded with a composite catalyst formed by Ni(OH)2 or NiO.

3. A method for preparing a magnesium-based hydrogen storage material containing Nb4N5 loaded with Ni-based active material, characterized in that: The steps are as follows: S1: Dissolve NbCl5 in anhydrous ethanol and stir until the solution is clear. Then add ammonia water, stir and react, and centrifuge to obtain a precipitate. Dissolve the precipitate in deionized water and place it in a blast drying oven for hydrothermal reaction. Centrifuge to obtain a precipitate, wash it with deionized water, and freeze-dry it to obtain a Nb4N5 precursor. S2: The Nb4N5 precursor prepared in step S1 is subjected to temperature-programmed nitridation, placed in a ceramic crucible, and calcined in a tube furnace by introducing ammonia gas to obtain a Nb4N5 catalyst; S3: dissolving NiCl2·6H2O in deionized water to obtain solution 1, stirring the Nb4N5 catalyst prepared in step S2 with deionized water and ultrasonically obtaining solution 2, adding solution 1 to solution 2, stirring and reacting in a water bath, adding ammonia water to adjust the pH to 8-12, washing the precipitate with deionized water and anhydrous ethanol by centrifugation, and drying to obtain a Ni(OH)2@Nb4N5 catalyst, and calcining the Ni(OH)2@Nb4N5 catalyst under an argon atmosphere to obtain a 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.

4. The preparation method according to claim 3, characterized in that In step S1, the mass volume ratio of NbCl5, anhydrous ethanol and ammonia water is: 0.5-1:5-20:8-60, g:mL:mL; the concentration of the ammonia water is 4-25%, the stirring reaction conditions are: stirring the reaction at a rate of 200-800 rpm for 1-10 hours, and the hydrothermal reaction conditions are: reacting at 180-250°C in the reactor for 12-36 hours.

5. The preparation method according to claim 3, characterized in that The specific parameters of the programmed temperature nitriding in step S2 are: heating to 600° C. to 900° C. at a heating rate of 2 to 10° C. / min, and calcining for 2 to 8 hours.

6. The preparation method according to claim 3, 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 the reaction at a rate of 200-800 rpm for 10-60 minutes; the stirring reaction conditions in the water bath are: stirring the reaction at a rate of 200-800 rpm in a water bath at 40°C-80°C for 1-10 hours; the centrifugal washing conditions are: centrifugal washing 3-5 times with deionized water / anhydrous ethanol at a speed of 3000-8000 rpm; and the drying conditions are: vacuum drying at 60-100°C for 8-16 hours.

7. The preparation method according to claim 3 or 4, characterized in that The mechanical ball mill uses stainless steel balls, argon as the ball milling atmosphere, a ball-to-material ratio of 10 to 40:1, a ball milling time of 5 to 12 hours, a ball milling speed of 350 rpm to 500 rpm, and intermittent ball milling in forward and reverse directions: after each ball milling for 5 to 30 minutes, pause for 5 to 30 minutes and reverse the direction.

8. Use of the magnesium-based hydrogen storage material according to claim 1 or 2 in solid-state hydrogen storage.

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