High-entropy alloy loaded transition metal oxide composite catalyst for hydrogen storage and preparation method thereof

Abstract

The invention relates to a high-entropy alloy loaded transition metal oxide composite catalyst for hydrogen storage and a preparation method thereof.The preparation method of the composite catalyst comprises the steps that an iron source, a cobalt source, a nickel source, a chromium source, a copper source and terephthalic acid are dissolved in an organic solvent, ultrasonic oscillation is conducted till all the materials are dissolved to form a transparent solution, and a solution A is obtained; transferring the solution A into a high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing and heating, and cooling to obtain a solution B; successively adding absolute ethyl alcohol and deionized water into the solution B, and centrifugally cleaning the solution to obtain a colloidal precursor; transferring the colloidal precursor into a vacuum oven, and drying to obtain precursor solid particles; and calcining the precursor solid particles in an argon atmosphere to obtain the composite catalyst. The high-entropy alloy loaded transition metal oxide composite catalyst has excellent hydrogen storage performance when applied to a magnesium hydride-based solid hydrogen production material.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage materials technology, and relates to a high-entropy alloy supported transition metal oxide composite catalyst for hydrogen storage and its preparation method, as well as nano-hydride magnesium-based hydrogen storage materials. Background Technology

[0002] Magnesium-based solid-state hydrogen storage faces key challenges such as high thermodynamic stability and slow kinetics. Therefore, catalysts play a crucial role in improving solid-state hydrogen storage materials, especially in magnesium-based composite hydrogen storage materials. Catalysts can effectively promote the reaction between the composite material and hydrogen molecules, achieving efficient hydrogen adsorption and desorption. Highly efficient catalysts, even in small amounts, can significantly enhance the hydrogen storage performance of the composite material. Finding a suitable catalyst to improve the hydrogen storage performance of materials has become a research hotspot in recent years.

[0003] The ways to improve the above problems include alloying, nano-sizing, doping with transition metals and their compounds, and loading with carbon-based materials. Some studies in recent years have found that transition metals and their compounds have a good effect on improving the hydrogen storage performance of magnesium-based solid hydrogen storage materials. The catalytic effect has several different mechanisms, such as generating intermetallic hydrides to break the chemical bond between magnesium and hydrogen; providing a larger specific surface area and active sites; and generating more defects at the interface to facilitate hydrogen adsorption. It can be judged that doping with transition metals and their compounds is a very effective way to improve the performance of magnesium-based solid hydrogen storage materials. Among them, the literature (Amirkhiz BS, Zahiri B, Kalisvaart P, et al. Synergy of elemental Fe and Ti promoting low temperature hydrogen sorption cycling of magnesium[J]. International Journal of Hydrogen Energy, 2011, 36(11): 6711-6722.) introduced transition metal elements Fe and Ti into magnesium hydride by high-energy ball milling and achieved submicron size of magnesium hydride particles and excellent nanoscale catalyst dispersion. Performance testing revealed that the ternary Mg-Fe-Ti composite material exhibited the best performance and significantly less degradation during cycling. This is attributed to titanium hydride acting as a size control agent to prevent particle agglomeration, while Fe is a very strong catalyst, resulting in uniform and nanoscale dispersion on the surface of MgH2 particles.

[0004] However, existing hydrogen storage materials generally suffer from the following problems: 1. High initial / peak hydrogen release temperature leads to high operating temperature; 2. Significant agglomeration occurs after multiple cycles of hydrogen absorption and desorption, resulting in a significant decline in cycle performance; 3. Existing hydrogen storage materials cannot absorb hydrogen at room temperature under a hydrogen pressure of 3 MPa and can only achieve hydrogen saturation at 250°C, while the composite system of this invention can achieve hydrogen absorption at room temperature and hydrogen saturation at 150°C. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage and its preparation method, as well as a nano-sized magnesium hydride-based hydrogen storage material. The magnesium hydride-based solid hydrogen production material obtained based on the high-entropy alloy-supported transition metal oxide composite catalyst has excellent hydrogen storage performance.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage, the composite catalyst comprising a transition metal oxide and high-entropy alloy particles supported on the transition metal oxide, wherein the high-entropy alloy particles are an iron-cobalt-nickel-chromium-copper high-entropy alloy.

[0007] In a second aspect, the present invention provides a method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage, comprising the following steps: S1. Weigh out the iron source, cobalt source, nickel source, chromium source, copper source and terephthalic acid and add them to the organic solvent. Sonicate until completely dissolved to form a transparent solution. S2. Place the transparent solution in S1 in a high-pressure reactor, seal and heat it, then cool and wash it to obtain a colloidal precursor. Then dry and grind it to obtain a precursor solid powder. S3. The precursor solid powder obtained in S2 is calcined under an inert atmosphere to obtain a composite catalyst.

[0008] Furthermore, the iron source is ferric nitrate or its hydrate, preferably ferric nitrate nonahydrate; the cobalt source is cobalt nitrate or its hydrate, preferably cobalt nitrate hexahydrate; the nickel source is nickel nitrate or its hydrate, preferably nickel nitrate hexahydrate; the chromium source is chromium nitrate or its hydrate, preferably chromium nitrate trihydrate; and the copper source is copper nitrate or its hydrate, preferably copper nitrate trihydrate.

[0009] Furthermore, the organic solvent is a mixed solvent of dimethylformamide and isopropanol, with a volume ratio of dimethylformamide to isopropanol of 12:1 to 10:1.

[0010] Furthermore, in S1, the ultrasonic oscillation time is 1~3h.

[0011] Furthermore, in S2, the temperature of the sealed heating is 110-130℃, and the time is 10-15h.

[0012] Furthermore, in S2, the washing process is as follows: the washing is performed by alternating between anhydrous ethanol and deionized water 3-5 times, each time for 5-10 minutes, and the last washing is with deionized water. The drying process is as follows: drying time is 10-15 hours, and drying temperature is 50-80℃.

[0013] Furthermore, in S3, the calcination process is as follows: first, the temperature is raised to 300-350℃ (for example, it can be 300℃, 320℃, or 350℃), and held for 2-3 hours (for example, it can be 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, or 3.0 hours, etc.), and then the temperature is raised to 500-550℃ (for example, it can be 510℃, 530℃, or 550℃, etc.), and held for 2-3 hours.

[0014] The solvothermal reaction in the high-pressure reactor promoted the reduction reaction of transition metal ions. Subsequent calcination at 300°C effectively removed organic ligands and impurities, promoting initial reactions between metal ions to form stable metal oxides or alloy phases. The product was then further calcined at 550°C to improve its crystallinity. This process initiated the reduction reaction and phase transformation of the metal oxides, resulting in a high-entropy alloy. Simultaneously, due to the limited amount of reducing agent, a small amount of Fe₂O₃ remained unreduced. Thus, the target catalyst FeCoNiCrCu / Fe₂O₃@C was successfully prepared.

[0015] Furthermore, in S3, the inert atmosphere is provided by argon or nitrogen.

[0016] In a third aspect, the present invention provides a nano-magnesium hydride-based hydrogen storage material comprising the following components in parts by weight: 90-97 parts magnesium hydride and 3-10 parts of the composite catalyst as described in the first aspect above.

[0017] Furthermore, magnesium hydride was mixed with a composite catalyst and then ball-milled under an inert atmosphere to obtain nano-sized magnesium hydride-based hydrogen storage materials.

[0018] The present invention provides a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage. Due to its unique high-entropy effect and lattice distortion characteristics, the high-entropy alloy tends to exist in solid solution form and is uniformly loaded on the surface of the transition metal oxide. This structure exhibits excellent stability during hydrogenation / dehydrogenation, providing a stable catalytic environment for hydrogen storage reactions. During ball milling, the high-entropy alloy can be uniformly dispersed on the MgH2 surface, forming a highly uniform catalyst distribution. This uniform distribution not only increases the contact area between the catalyst and MgH2 but also enhances the accessibility of catalytic active sites, thereby significantly improving catalytic efficiency. The catalytic mechanism of the high-entropy alloy mainly stems from its "cocktail effect," namely the synergistic effect between multiple metal elements (such as Cr, Mn, Fe, Co, and Ni) in the alloy. These elements each possess unique catalytic properties, and through their interaction within the high-entropy alloy, a synergistic enhancement of catalytic activity is achieved. Specifically, the multi-elemental composition of the high-entropy alloy leads to a highly heterogeneous surface, forming abundant active sites. These active sites provide diverse pathways for hydrogen adsorption, dissociation, and diffusion, significantly accelerating hydrogen transport at the Mg / MgH2 interface and thus improving the hydrogen storage performance of MgH2.

[0019] In summary, the high-entropy effect and lattice distortion characteristics of high-entropy alloys enable them to exhibit excellent catalytic performance in hydrogen storage reactions, while their composite structure with transition metal oxides further enhances the stability and activity of the catalyst.

[0020] Compared with the prior art, the present invention has the following advantages: (1) The raw materials for the preparation method provided by the present invention are readily available and relatively inexpensive.

[0021] (2) The preparation method provided by this invention is relatively simple, easy to operate, and has a short experimental cycle. The liquid phase preparation method used in this invention is conducive to the uniform distribution of catalyst components and can further improve the synergistic catalytic performance.

[0022] (3) The composite catalyst prepared by the present invention contains a high-entropy alloy particle, namely iron-cobalt-nickel-chromium-copper alloy particle, which has good loading and dispersion on the transition metal oxide; the transition metal oxide used is not a ready-made material, but is generated simultaneously with the high-entropy alloy during the calcination process, so that the high-entropy alloy particle is well loaded onto the transition metal oxide.

[0023] (4) The high-entropy alloy supported transition metal oxide composite material (i.e., high-entropy alloy supported transition metal oxide composite catalyst for hydrogen storage) synthesized in this invention not only has the excellent properties of high-entropy alloy, but also has the excellent catalytic performance of transition metal oxide. It can be used more widely in many fields such as catalysts, water electrolysis hydrogen production materials, hydrogen storage materials, battery materials, supercapacitors and optoelectronic materials. Attached Figure Description

[0024] Figure 1 The X-ray diffraction (XRD) pattern of the magnesium hydride and high-entropy alloy-supported transition metal oxide composite material after ball milling in Example 1 of this invention is shown.

[0025] Figure 2 This is a scanning electron microscope (SEM) image of the high-entropy alloy-supported transition metal oxide composite material of Example 1 of the present invention.

[0026] Figure 3 This is the EDS energy spectrum of the high-entropy alloy-supported transition metal oxide composite material of Example 1 of the present invention.

[0027] Figure 4 The TPD curve of magnesium hydride catalyzed by high-entropy alloy-supported transition metal oxide composite material in Example 1 of the present invention is shown.

[0028] Figure 5 The DSC curves of the high-entropy alloy-supported transition metal oxide composite material of Example 1 of the present invention and Comparative Examples 1, 2, and 3 at a heating rate of 2.5 °C / min are shown. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0031] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0035] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0036] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0037] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0038] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0039] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0040] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0041] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0042] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0044] Example 1: A high-entropy alloy-supported transition metal oxide composite material (i.e., a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage), wherein the atomic ratio of metal elements in the high-entropy alloy and the transition metal oxide is 1:1:1:1:1, is prepared by the following method: First, Fe(NO3)2•9H2O (1 mmol), Co(NO3)2•3H2O (1 mmol), Ni(NO3)2•6H2O (1 mmol), Cr(NO3)2•3H2O (1 mmol), and Cu(NO3)2•3H2O (1 mmol) were dissolved in a mixed solution of DMF (dimethylformamide) and IPA (isopropanol). The solution was ultrasonically vibrated for 2 hours until completely dissolved to form a transparent solution. Then, the solution was transferred to a high-pressure reactor and heated at 120°C for 12 hours to obtain the precursor product. The precursor product was washed three times with anhydrous ethanol and deionized water at 8000 rpm for three minutes each time to obtain a colloidal precursor. The colloidal precursor was then dried in a forced-air oven at 60°C for 24 hours to obtain a solid precursor. The solid precursor powder was spread evenly in a crucible and placed in a tube furnace cavity. The furnace was heated to 300°C at a heating rate of 4°C / min under an Ar atmosphere. After holding at ℃ for 2 hours, the temperature was increased to 550℃ at a rate of 4℃ / min, held for 2 hours, and then allowed to cool naturally to obtain the FeCoNiCrCu@Fe2O3 catalyst.

[0045] Then, 0.36 g of magnesium hydride powder and 0.04 g of high-entropy alloy-supported transition metal oxide composite material were placed in a ball mill jar. The ball milling process was carried out under argon atmosphere protection for 5 hours. The ball-to-material ratio (i.e., the ratio of the mass of steel balls to the total mass of the two raw materials, magnesium hydride powder and high-entropy alloy-supported transition metal oxide powder) was 30:1, and the rotation speed was 400 r / min. Nano-sized magnesium hydride / high-entropy alloy-supported transition metal oxide powder was obtained, which yielded the nano-sized magnesium hydride-based hydrogen storage material.

[0046] The hydrogen storage performance of the prepared nano-hydride magnesium-based hydrogen storage material was tested: the DSC curve of MgH2+10% FeCoNiCrCu@Fe2O3 was tested at a heating rate of 2.5℃ / min, and its dehydrogenation peak temperature was 268℃; the TPD curve of MgH2+10% FeCoNiCrCu@Fe2O3 was tested at a heating rate of 2℃ / min, and its initial dehydrogenation temperature was 180℃ and dehydrogenation was complete before 300℃, with a dehydrogenation amount of 6.3wt%.

[0047] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the magnesium hydride and high-entropy alloy-loaded transition metal oxide composite material after ball milling in Example 1. It can be seen from the figure that the phase composition of the composite material is iron-cobalt-nickel-chromium-copper high-entropy alloy and magnesium hydride. Due to the amorphization of iron oxide caused by ball milling, it cannot be detected in the XRD pattern.

[0048] Figure 2 This is a scanning electron microscope (SEM) image of the high-entropy alloy-supported transition metal oxide composite material prepared in Example 1. The image shows the iron oxide carrier and the high-entropy alloy particles encapsulated within it, with the alloy particles being evenly distributed.

[0049] Figure 3 The image shows the EDS spectrum of the high-entropy alloy-supported transition metal oxide composite material prepared in Example 1. It can be seen from the image that the six elements, iron, cobalt, nickel, chromium, copper and oxygen, are very uniformly dispersed and are consistent with the morphology of the scanning electron microscope.

[0050] Figure 4 This is the XPS spectrum of the high-entropy alloy-supported transition metal oxide composite catalyst from Example 1, from which Fe can be observed. 3+ and O L The peaks (and lattice oxygen) can confirm the presence of iron oxide.

[0051] Figure 5The figures show the DSC curves of the high-entropy alloy-supported transition metal oxide composite material of Example 1 and Comparative Examples 1, 2, and 3 at a heating rate of 2.5 °C / min. The peak dehydrogenation temperatures of Example 1 (i.e., Comparative Examples 1, 2, and 3) are 268 °C, 325 °C, 290 °C, and 329 °C, respectively. The comparison shows that the dehydrogenation temperature of Example 1 is significantly lower.

[0052] Therefore, the catalyst in this embodiment exhibits good performance, partly because the high-entropy alloy-supported transition metal oxide composite material, after appropriate ball milling, is relatively uniformly dispersed and well-integrated with magnesium hydride. During the catalytic process, the presence of Fe2O3 provides a support for the high-entropy alloy, and the "cocktail effect" of the high-entropy alloy—the synergistic effect among multiple metal elements (such as Cr, Mn, Fe, Co, and Ni)—achieves a synergistic enhancement of catalytic activity. This results in a MgH2+10% FeCoNiCrCu@Fe2O3 composite material with excellent hydrogen desorption performance.

[0053] Comparative Example 1 A composite hydrogen storage material of magnesium hydride and iron oxide, wherein the mass ratio of the two is 9:1.

[0054] 0.9 g of magnesium hydride and 0.1 g of iron oxide were weighed using an electronic balance. The additive (iron oxide) and magnesium hydride were ground together using a planetary ball mill for 5 hours at a speed of 400 r / min, with a ball-to-material mass ratio of 30:1. The resulting magnesium hydride-based composite hydrogen storage material (named MgH2+10%Fe2O3) was then tested. The hydrogen storage performance of the prepared MgH2+10%Fe2O3 material was tested: the DSC curve of MgH2+10%Fe2O3 was measured at a heating rate of 2.5℃ / min, and its dehydrogenation peak temperature was 325℃. Compared with Example 1, it can be seen that the hydrogen desorption performance of the composite material is significantly lower when only iron oxide is added.

[0055] Comparative Example 2 A composite hydrogen storage material of magnesium hydride and high-entropy alloy, wherein the mass ratio of the two is 9:1.

[0056] 0.9 g of magnesium hydride and 0.1 g of high-entropy alloy were weighed using an electronic balance. The additive (high-entropy alloy) and magnesium hydride were ground together using a planetary ball mill for 5 hours at a speed of 400 r / min, with a ball-to-material mass ratio of 30:1. The resulting magnesium hydride-based composite hydrogen storage material (named MgH2+10%FeCoNiCeCu) was then tested. The hydrogen storage performance of the prepared MgH2+10%FeCoNiCeCu material (prepared by replacing the argon atmosphere with a 5% hydrogen-argon mixture, referring to Example 1) was tested: the DSC curve of MgH2+10%FeCoNiCeCu was measured at a heating rate of 2.5 °C / min, and its dehydrogenation peak temperature was 290 °C. This indicates that when the high-entropy alloy acts alone, its catalytic efficiency is significantly lower than that of Example 1.

[0057] Comparative Example 3 A composite hydrogen storage material consisting of magnesium hydride, high-entropy alloy, and iron oxide, with a mass ratio of 9:0.5:0.5.

[0058] 0.9 g of magnesium hydride powder, 0.05 g of high-entropy alloy, and 0.05 g of iron oxide were placed in a ball mill jar. The ball milling process was carried out under an argon atmosphere for 5 h, with a ball-to-material ratio (i.e., the ratio of the mass of steel balls to the mass of magnesium hydride powder) of 30:1 and a rotation speed of 400 r / min, to obtain a composite hydrogen storage material (named MgH2+5%FeCoNiCeCu+5%Fe2O3). The DSC curve of MgH2+5%FeCoNiCeCu+5%Fe2O3 was tested at a heating rate of 2.5℃ / min, and its dehydrogenation peak temperature was 329℃. It can be seen that when MgH2 is simply physically mixed with FeCoNiCeCu and Fe2O3, the catalytic effect is significantly reduced compared to Example 1.

[0059] The difference between Example 1 and Comparative Examples 1-3 is that Example 1 uses a high-entropy alloy supported transition metal oxide composite material as a catalyst to test catalytic performance, Comparative Example 1 uses iron oxide as a catalyst to test catalytic performance, Comparative Example 2 uses a high-entropy alloy as a catalyst to test catalytic performance, and Comparative Example 3 uses a physical mixture of iron oxide and high-entropy alloy as a catalyst to test performance.

[0060] Comparative Example 4: Compared to Example 1, most aspects were the same, except that the calcination process was directly changed to calcination at 550℃ for 4 hours. The target product was obtained and ball-milled with magnesium hydride at the same mass ratio as in Example 1. A planetary ball mill was used to grind the additive and magnesium hydride for 5 hours at a speed of 400 r / min, with a ball-to-material mass ratio of 30:1. The final product was a magnesium hydride-based composite hydrogen storage material (MgH2+10%FeCoNiCeCu@Fe2O3-550). The hydrogen storage performance of the prepared material was tested: its DSC curve was tested at a heating rate of 2.5℃ / min, and its dehydrogenation peak temperature was 278℃. Compared with Example 1, it can be seen that the organic solvent impurities were not completely removed due to the lack of calcination at 300℃, resulting in a slight decrease in catalyst performance.

[0061] Comparative Example 5: Compared to Example 1, most aspects were the same, except that the calcination process was directly changed to calcination at 300℃ for 4 hours. The target product was obtained and ball-milled with magnesium hydride at the same mass ratio as in Example 1. A planetary ball mill was used to grind the additive and magnesium hydride for 5 hours at a speed of 400 r / min, with a ball-to-material mass ratio of 30:1. The final product was a magnesium hydride-based composite hydrogen storage material (MgH2+10%FeCoNiCeCu@Fe2O3-300). The hydrogen storage performance of the prepared material was tested: its DSC curve was tested at a heating rate of 2.5℃ / min, and its dehydrogenation peak temperature was 305℃. Compared with Example 1, it can be seen that because there was no calcination treatment at 550℃, the transition metal elements did not undergo sufficient redox reaction, resulting in incomplete alloying and thus only a target product with lower crystallinity was obtained.

[0062] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage, characterized in that, The composite catalyst consists of transition metal oxide Fe2O3 and high-entropy alloy particles supported on the transition metal oxide, wherein the high-entropy alloy particles are an iron-cobalt-nickel-chromium-copper high-entropy alloy.

2. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage as described in claim 1, characterized in that, Includes the following steps: S1. Weigh out the iron source, cobalt source, nickel source, chromium source, copper source and terephthalic acid and add them to the organic solvent. Sonicate until completely dissolved to form a transparent solution. S2. Place the transparent solution in S1 in a high-pressure reactor, seal and heat it, then cool and wash it to obtain a colloidal precursor. Then dry and grind it to obtain a precursor solid powder. S3. The precursor solid powder obtained in S2 is calcined under an inert atmosphere to obtain a composite catalyst.

3. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, The iron source is ferric nitrate or its hydrate, the cobalt source is cobalt nitrate or its hydrate, the nickel source is nickel nitrate or its hydrate, the chromium source is chromium nitrate or its hydrate, and the copper source is copper nitrate or its hydrate.

4. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, The organic solvent is a mixture of dimethylformamide and isopropanol, with a volume ratio of dimethylformamide to isopropanol of 12:1 to 10:

1.

5. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, In S2, the temperature for sealing and heating is 110-130℃, and the time is 10-15h.

6. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, In S2, the washing process is as follows: the washing is performed by alternating between anhydrous ethanol and deionized water 3-5 times, each time for 5-10 minutes, and the last washing is done with deionized water. The drying process is as follows: drying time is 10-15 hours, and drying temperature is 50-80℃.

7. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, In S3, the calcination process is as follows: first, the temperature is raised to 300-350℃ and held for 2-3 hours, then the temperature is raised to 500-550℃ and held for 2-3 hours.

8. The method for preparing a high-entropy alloy-supported transition metal oxide composite catalyst for hydrogen storage according to claim 2, characterized in that, In S3, the inert atmosphere is provided by argon or nitrogen.

9. A nano-magnesium hydride-based hydrogen storage material, characterized in that, It comprises the following components in parts by weight: 90-97 parts magnesium hydride, and 3-10 parts of the composite catalyst as described in claim 1.

10. The method for preparing the nano-sized magnesium hydride-based hydrogen storage material as described in claim 9, characterized in that, Magnesium hydride was mixed with a composite catalyst and then ball-milled under an inert atmosphere to obtain nano-sized magnesium hydride-based hydrogen storage materials.

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