A high-entropy multi-metal organic framework assisted enhanced magnesium hydride solid hydrogen storage material

Abstract

This invention relates to a high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material, which is composed of magnesium hydride and a high-entropy polymetallic organic framework in a mass ratio of 30-90:10-70, and its chemical formula is MgH. 2 -(FeCoNiCrMn) 3 O 4 The high-entropy multimetal-organic framework is composed of five different metal cations coordinated in an equimolar ratio; the metal cations are selected from cobalt, nickel, iron, chromium, and manganese. The material of this invention exhibits a high-entropy effect and possesses excellent thermodynamic properties and hydrogen storage cycle performance.

Description

A high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material Technical Field

[0001] This invention relates to the field of solid-state hydrogen storage materials, and more particularly to a high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material. Background Technology

[0002] Hydrogen, as a clean energy carrier with zero carbon emissions, typically exists in gaseous form and is flammable and explosive. Therefore, the storage and transportation of hydrogen at normal temperature and pressure presents many technical challenges. Achieving efficient, safe, and low-cost hydrogen storage technology is one of the core challenges in developing a hydrogen society. Among these, metal hydrides (such as MgH2) have become ideal candidates for solid-state hydrogen storage materials due to their high theoretical mass hydrogen storage density of 7.6 wt%, good reversibility, and abundant resource base. However, the stable thermodynamics and slow hydrogen absorption and desorption kinetics of MgH2 greatly hinder its commercial application.

[0003] Current research focuses on reducing the hydrogen desorption temperature of magnesium hydride and promoting its hydrogen absorption and desorption reaction rates, with substantial progress achieved. Among these efforts, catalyst addition is considered one of the most effective methods to improve the hydrogen storage performance of magnesium hydride. High-entropy layered metal oxides, single-atom and two-dimensional transition metal carbonitrides (Mxenes), spinels, and nitrides exhibit good catalytic hydrogen storage performance and cycle stability, and have been used as solid-state hydrogen storage materials for magnesium hydride. For example, Wang et al. designed a TiN-decorated graphene catalyst and doped it into a MgH2 system. A 10 wt% TiN@rGO-doped MgH2 sample began releasing hydrogen at approximately 167 °C, and released approximately 6.0 wt% hydrogen within 18 minutes at 300 °C. Zhong et al. synthesized a heat-treated derivative of nickel-manganese base-like double hydroxide, NiMn-LMO. MgH2+ 9 wt% Ni3Mn-LMO began to release hydrogen at 190 °C, and under isothermal conditions at 295 °C, it released 6.59 wt% hydrogen gas within 5 minutes. Even at a low temperature of 250 °C, MgH2+ 9 wt% Ni3Mn-LMO still released 5.02 wt% hydrogen gas within 11 minutes, with its dehydrogenation activation energy decreasing to 86.88 ± 6.48 kJ·mol⁻¹. −1 .

[0004] In recent years, high-entropy polymetallic organic frameworks (PHOMAs) have attracted widespread research interest in fields such as energy storage and conversion. PHOMAs possess high configurational entropy, enabling them to tolerate high levels of doping with various metal ions. Furthermore, their multi-component nature provides a prerequisite for optimizing the functional properties of these materials. However, reports on the application of PHOMAs in solid-state hydrogen storage are relatively limited. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a high-performance high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0006] To address the aforementioned problems, the present invention provides a high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material, characterized in that: the material is composed of magnesium hydride and a high-entropy polymetallic organic framework in a mass ratio of 30~90:10~70, and its chemical formula is MgH2-(FeCoNiCrMn)3O4; the high-entropy polymetallic organic framework is composed of five different metal cations coordinated together, and the metal atoms are in an equimolar ratio; the metal cations are selected from cobalt, nickel, iron, chromium, and manganese.

[0007] The material's initial dehydrogenation temperature is reduced to 220℃, and its hydrogen storage capacity retention rate is over 95% under conditions of 310℃, 30 bar, and 70 cycles of absorption and dehydrogenation.

[0008] The average particle size of this material is in the range of 200–900 nm.

[0009] The high-entropy multimetallic organic framework is prepared by the following method: polyether F127 is added to a solution composed of deionized water and anhydrous ethanol, and then the pH is adjusted to 7-9 with an ammonia solution; after half an hour, tannic acid and glutaraldehyde solution are added under stirring, and the mixture is stirred for 12-24 hours. Then, a precursor solution is added, which is a nitrate of five metals: cobalt, nickel, iron, chromium and manganese, with the metal atoms in an equimolar ratio; stirring is continued for 12-16 hours, and the resulting solution is then subjected to hydrothermal treatment and high-temperature calcination to obtain the final product.

[0010] The ratio of the polyether F127, the deionized water, and the anhydrous ethanol is 0.1~0.5 g: 47 mL: 8 mL.

[0011] The ratio of the polyether F127, tannic acid, glutaraldehyde solution to the precursor solution is 0.1~0.5 g: 0.1~1 g: 0.5~2 g: 1~3 mL.

[0012] The conditions for hydrothermal treatment are a hydrothermal temperature of 80~120 ℃ and a hydrothermal time of 9~15 hours.

[0013] The conditions for high-temperature calcination are a calcination temperature of 400~900 ℃, a heating rate of 3~10 ℃ / min, and a calcination time of 1~4 hours.

[0014] The preparation method of the high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material as described above is characterized by: firstly, weighing according to the ratio; then, ball milling the magnesium hydride and the high-entropy polymetallic organic framework together at a speed of 200~500 r / min, rotating forward for 15 min, rotating backward for 15 min, with a 12 min interval in between, which constitutes one ball milling cycle, and ball milling for 24~48 hours to obtain the high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The chemical formula of the high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material of this invention is MgH2-(FeCoNiCrMn)3O4. The high-entropy multimetal-organic framework introduces a variety of transition metals (such as Fe, Co, Ni, Cr, etc.) to form a high configurational entropy system. The diversity of its metal nodes can produce a synergistic catalytic effect. Secondly, the microporous / mesoporous structure of the organic framework can physically confine MgH2 nanoparticles, inhibit their aggregation and grain growth, and maintain a high specific surface area. At the same time, the multi-level pore structure (such as microporous-mesoporous composite) provides a fast transport path for hydrogen molecules, shortens the diffusion distance, and improves the kinetic performance.

[0017] 2. This invention employs an entropy-driven high-entropy stabilization strategy to synthesize a novel high-entropy organic framework material that is rich in defects and small in size. This material is characterized by a single phase, high purity, small particle size, and uniform elemental distribution.

[0018] 3. In the high-entropy spinel structure (FeCoNiCrMn)3O4 derived from the high-entropy multimetallic organic framework of this invention, five transition metals randomly occupy tetrahedral (A-site) and octahedral (B-site) sites, resulting in significant lattice distortion. This distortion forms a continuous stress field in the spinel lattice, providing a low-energy diffusion path for hydrogen atoms. At the same time, the lattice constant of the high-entropy spinel is mismatched with the lattice formed by MgH2 (a=4.52 Å), generating compressive strain at the interface and weakening the covalent nature of the Mg-H bond.

[0019] 4. In the material described in this invention, multiple transition metal elements form multiple impure d-electron intermediate energy levels, which is beneficial for reducing the band gap. Simultaneously, the size differences of the doping elements lead to a lattice distortion effect, which can improve hydrogen storage cycle performance. Furthermore, the synergistic effect between the highly dispersed metal catalytic centers and hierarchical adsorption sites enables this composite material to achieve excellent catalytic hydrogen storage performance with a relatively low catalyst loading.

[0020] 5. The material described in this invention exhibits a high entropy effect and excellent thermodynamic properties, enabling dehydrogenation at 220 °C. This superior performance is attributed to the ability of electronic interactions between multiple metals to modulate the electronic structure of the catalyst, optimizing its adsorption and dissociation capabilities for hydrogen molecules, thereby lowering the dehydrogenation temperature.

[0021] 6. This invention employs the traditional hydrothermal method and high-temperature calcination method, and further combines ball milling with magnesium hydride ball milling to prepare high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage materials, which are suitable for industrial-scale production. Attached Figure Description

[0022] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Figure 1 is a SEM image of MgH2-(FeCoNiCrMn)3O4 in Example 1 of the present invention.

[0024] Figure 2 is a temperature-programmed hydrogen desorption performance (TPD) test diagram of MgH2-(FeCoNiCrMn)3O4 in Example 1 of the present invention.

[0025] Figure 3 is a test diagram of the hydrogen absorption and dehydrogenation cycle of MgH2-(FeCoNiCrMn)3O4 in Example 1 of the present invention. Detailed Implementation

[0026] A high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material is disclosed. The material is composed of magnesium hydride and a high-entropy polymetallic organic framework in a mass ratio of 30~90:10~70 (g / g), and its chemical formula is MgH2-(FeCoNiCrMn)3O4. The high-entropy polymetallic organic framework is composed of five different metal cations coordinated in an equimolar ratio. The metal cations are selected from cobalt, nickel, iron, chromium, and manganese.

[0027] The material exhibits a reduced initial dehydrogenation temperature of 220℃ and maintains a hydrogen storage capacity retention of over 95% under conditions of 310℃, 30 bar, and 70 adsorption-dehydrogenation cycles. Furthermore, the average particle size of this material ranges from 200 to 900 nm.

[0028] The high-entropy multimetallic organic framework was prepared as follows: Polyether F127 was added to a solution composed of deionized water and anhydrous ethanol, with a ratio of 0.1~0.5 g: 47 mL: 8 mL. The pH was then adjusted to 7~9 with ammonia solution. After half an hour, tannic acid and glutaraldehyde solution were added with stirring, and the mixture was stirred for 12~24 hours. A precursor solution was then added, consisting of five metal nitrates: cobalt, nickel, iron, chromium, and manganese, with an equimolar ratio of metal atoms (0.04~0.06 mol / L). The ratio of polyether F127, tannic acid, glutaraldehyde solution to precursor solution was 0.1~0.5 g: 0.1~1 g: 0.5~2 g: 1~3 mL. Continue stirring for 12-16 hours. The resulting solution is first hydrothermally treated at 80-120 ℃ for 9-15 hours, and then calcined at a high temperature of 400-900 ℃, a heating rate of 3-10 ℃ / min, and a calcination time of 1-4 hours to obtain the final product.

[0029] A method for preparing a high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material: First, weigh the materials according to the specified ratio; then, ball mill the magnesium hydride and the high-entropy polymetallic organic framework together at a speed of 200~500 r / min, rotating clockwise for 15 min, counterclockwise for 15 min, with a 12 min interval in between, which constitutes one ball milling cycle. The ball milling is carried out for 24~48 hours to obtain the high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0030] Example 1: A method for preparing a high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material:

[0031] Step 1: 0.10 g of F127 was added to 55 mL of a solution (composed of 47 mL of deionized water and 8 mL of anhydrous ethanol), and the pH was adjusted to 7 with ammonia solution. After half an hour, 0.1 g of tannic acid and 0.5 g of glutaraldehyde solution were added with stirring, and the mixture was stirred for 12 hours. Then, 1 mL of an equimolar (0.04 mol / L) solution of iron, cobalt, nickel, chromium, and manganese metal nitrate precursors was added, and the mixture was stirred for 12 hours. The resulting solution was hydrothermally treated at 80 °C for 9 hours, and then calcined at 400 °C for 1 hour (heating rate of 3 °C / min) to obtain a high-entropy multimetallic organic framework.

[0032] Step 2: High-entropy polymetallic organic framework and magnesium hydride are ball-milled at a mass ratio (g / g) of 30:70. The rotation speed is 200 r / min, with 15 min of forward rotation, 15 min of reverse rotation, and a 12 min interval in between. This constitutes one ball-milling cycle. The ball-milling is carried out for 24 hours to obtain MgH2-(FeCoNiCrMn)3O4 high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0033] Figure 1 is a SEM image of the MgH2-(FeCoNiCrMn)3O4 high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material described in Example 1. The image reveals numerous granular structures of varying sizes, mostly spherical or nearly spherical, with a few irregular shapes. The surface distribution is relatively uniform, with slight agglomeration in localized areas.

[0034] The hydrogen storage performance and cycle stability of the obtained MgH2-(FeCoNiCrMn)3O4 high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material were evaluated.

[0035] Test methods: The temperature-programmed hydrogen desorption / desorption performance (TPD) and cyclic hydrogen adsorption / desorption performance were tested using a domestically produced H-Sorb 2600 high-temperature and high-pressure gas adsorption instrument. The TPD test was conducted at a heating rate of 2 °C / min from room temperature to 500 °C; the cyclic hydrogen adsorption / desorption performance test was conducted at 310 °C, with hydrogen absorption and desorption pressures of 30 bar and 0.001 bar, respectively.

[0036] A 0.2 g sample of high-entropy polymetallic organic framework-enhanced magnesium hydride solid-state hydrogen storage material was placed in a sample tube and subjected to 70 cycles of stability testing at 310 °C and 30 bar. The results are shown in Figures 2 and 3. As can be seen from the figures, the high-entropy polymetallic organic framework-enhanced magnesium hydride solid-state hydrogen storage material begins to dehydrogenate at 220 °C, with a hydrogen storage capacity of 6.8 wt% in the first cycle; after 70 cycles of stability testing, its hydrogen storage capacity was measured to be 6.7 wt%.

[0037] Example 2: A method for preparing a high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material:

[0038] Step 1: 0.20 g of F127 was added to 55 mL of solution (composed of 47 mL of deionized water and 8 mL of ethanol), and the pH was adjusted to 8 with ammonia solution. After half an hour, 0.5 g of tannic acid and 1 g of glutaraldehyde solution were added with stirring, and the mixture was stirred for 15 hours. Then, 2 mL of iron, cobalt, nickel, chromium, and manganese metal nitrate precursor solution was added in equimolar amounts (0.05 mol / L), and the mixture was stirred for 16 hours. The resulting solution was hydrothermally treated at 120 °C for 15 hours, and then calcined at 900 °C for 4 hours (heating rate of 10 °C / min) to obtain a high-entropy multimetallic organic framework.

[0039] Step 2: The obtained high-entropy polymetallic organic framework and magnesium hydride were ball-milled at a mass ratio (g / g) of 40:60. The rotation speed was 500 r / min, with 15 min of forward rotation, 15 min of reverse rotation, and a 12 min interval in between. This constituted one ball-milling cycle. The ball-milling was carried out for 48 hours to obtain MgH2-(FeCoNiCrMn)3O4 high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0040] The hydrogen storage performance and cycle stability of the obtained MgH2-(FeCoNiCrMn)3O4 high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material were evaluated:

[0041] The testing methods and sample amounts were the same as in Example 1. The results showed that the hydrogen storage capacity of this high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material was 6.8 wt%. After a cycle stability test, its hydrogen storage capacity after 70 cycles was measured to be 6.68 wt%.

[0042] Example 3: A method for preparing a high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material:

[0043] Step 1: 0.50 g of F127 was added to 55 mL of solution (composed of 47 mL of deionized water and 8 mL of ethanol), and the pH was adjusted to 9 with ammonia solution. After half an hour, 1 g of tannic acid and 2 g of glutaraldehyde solution were added with stirring, and the mixture was stirred for 24 hours. Then, 3 mL of iron, cobalt, nickel, chromium, and manganese metal nitrate precursor solution was added in equimolar amounts (0.06 mol / L), and the mixture was stirred for 14 hours. The resulting solution was hydrothermally treated at 90 °C for 12 hours, and then calcined at 700 °C for 2 hours (heating rate of 5 °C / min) to obtain a high-entropy multimetallic organic framework.

[0044] Step 2: The obtained high-entropy polymetallic organic framework and magnesium hydride were ball-milled at a mass ratio (g / g) of 50:50. The rotation speed was 300 r / min, with 15 min of forward rotation, 15 min of reverse rotation, and a 12 min interval in between. This constituted one ball-milling cycle. The ball-milling was carried out for 30 hours to obtain MgH2-(FeCoNiCrMn)3O4 high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

[0045] The hydrogen storage performance and cycle stability of the obtained MgH2-(FeCoNiCrMn)3O4 high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material were evaluated:

[0046] The test methods and sample amounts were the same as in Example 1. The results showed that the hydrogen storage capacity of this high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material was 6.83 wt% in the first cycle. After cycle stability testing, its hydrogen storage capacity after 70 cycles was measured to be 6.70 wt%.

[0047] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. A high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material, characterized in that: This material is composed of magnesium hydride and a high-entropy polymetallic organic framework in a mass ratio of 30~90:10~70, with the chemical formula MgH2-(FeCoNiCrMn)3O4. The high-entropy polymetallic organic framework is composed of five different metal cations coordinated in an equimolar ratio. The metal cations are selected from cobalt, nickel, iron, chromium, and manganese. The material has an initial dehydrogenation temperature reduced to 220℃, and retains more than 95% of its hydrogen storage capacity under conditions of 310℃, 30 bar, and 70 cycles of adsorption and dehydrogenation.

2. The high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 1, characterized in that: The average particle size of this material is in the range of 200–900 nm.

3. The high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 1, characterized in that: The high-entropy multimetallic organic framework is prepared by the following method: polyether F127 is added to a solution composed of deionized water and anhydrous ethanol, and then the pH is adjusted to 7-9 with an ammonia solution; after half an hour, tannic acid and glutaraldehyde solution are added under stirring, and the mixture is stirred for 12-24 hours. Then, a precursor solution is added, which is a nitrate of five metals: cobalt, nickel, iron, chromium and manganese, with the metal atoms in an equimolar ratio; stirring is continued for 12-16 hours, and the resulting solution is then subjected to hydrothermal treatment and high-temperature calcination to obtain the final product.

4. The high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 3, characterized in that: The ratio of the polyether F127, the deionized water, and the anhydrous ethanol is 0.1~0.5 g: 47 mL: 8 mL.

5. The high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 3, characterized in that: The ratio of the polyether F127, tannic acid, glutaraldehyde solution to the precursor solution is 0.1~0.5 g: 0.1~1 g: 0.5~2 g: 1~3 mL.

6. The high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 3, characterized in that: The conditions for hydrothermal treatment are a hydrothermal temperature of 80~120 ℃ and a hydrothermal time of 9~15 hours.

7. A high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid-state hydrogen storage material as described in claim 3, characterized in that: The conditions for high-temperature calcination are a calcination temperature of 400~900 ℃, a heating rate of 3~10 ℃ / min, and a calcination time of 1~4 hours.

8. A method for preparing a high-entropy multimetal-organic framework-assisted reinforced magnesium hydride solid hydrogen storage material as described in any one of claims 1 to 7, characterized in that: First, weigh the materials according to the specified proportions. Then, ball mill the magnesium hydride and high-entropy polymetallic organic framework together at a speed of 200-500 r / min, rotating forward for 15 min, rotating backward for 15 min, with a 12 min interval in between. This constitutes one ball milling cycle. The ball milling process lasts for 24-48 hours, yielding a high-entropy polymetallic organic framework-assisted reinforced magnesium hydride solid hydrogen storage material.

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