Preparation method and application of high-entropy frame material for directionally growing nano array on porous metal substrate

Abstract

The invention discloses a preparation method and application of a high-entropy frame material for directionally growing a nano array on a porous metal substrate. The material takes a metal porous substrate as a carrier, and multiple transition metals are introduced into a metal organic framework crystal structure. The structure is helpful for improving the corresponding reaction activity and selectivity. In addition, compared with a traditional high-entropy material, the identified main high-entropy effect shows a more excellent performance enhancement effect. The preparation process of the material is simple, and meanwhile, the high-entropy material has excellent performance in the energy storage and conversion process and has industrial application prospects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material science, and relates to a preparation method of a high-entropy framework material and application thereof, in particular to a preparation method of a high-entropy framework material of a nanoarray grown on a porous metal substrate and application thereof. BACKGROUND

[0002] In recent years, the overconsumption of fossil fuels has triggered global energy and environmental crises, and energy shortages, greenhouse effects and environmental pollution problems need to be solved. Under this background, the development of efficient and sustainable new green renewable energy systems has become the core research direction in the field of energy and material science. Hydrogen energy technology is considered as one of the most promising energy solutions due to its high energy density and environmental friendly characteristics. Current research has made significant progress in the field of electrocatalytic materials, and noble metal-based materials have become the candidate materials to meet the commercial needs due to their excellent catalytic performance. However, its inherent limitations, including scarcity of crustal abundance, high cost and deactivation phenomenon in electrochemical process, seriously restrict its large-scale application. Developing high-performance non-noble metal alternative materials has become a key path to break through this technical bottleneck.

[0003] Catalyst size effect is a key factor in regulating its catalytic performance. When the size of the nanoparticle structure is reduced to the critical scale, the proportion of unsaturated coordination state of surface atoms is significantly improved, and a higher density of active sites is exposed to participate in the catalytic reaction. Using a framework material with a clear topological structure and excellent chemical stability as a carrier can effectively inhibit the migration and aggregation of metal nanoparticles, maximize the utilization rate of high active surface atoms, and thus construct an electrocatalytic system with low noble metal loading and excellent catalytic performance. In recent years, high-entropy materials (HEMs) have shown great potential in the field of energy catalysis due to their unique component adjustability, unsaturated coordination environment and structural stability advantages. The core mechanism is as follows: 1) high configurational entropy induced lattice distortion effect significantly widens the electronic structure regulation window of active sites; 2) multiple component synergistic optimization of reaction intermediate adsorption energy; 3) delayed diffusion effect enhances the stability of the material in the electrochemical environment. These characteristics collectively promote the mass transfer and activation kinetics of active species, making HEMs exhibit superior overall reaction efficiency in the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and other processes. Therefore, how to combine theoretical simulation and experimental verification to systematically design high-entropy catalysts with precise component distribution and stable structure has become a scientific challenge that needs to be broken through in this field.

[0004] Metal-Organic Frameworks (MOFs) are considered as ideal catalytic platforms for multifunctional integration due to their programmable pore structure and well-defined metal node arrangement. Their ordered crystal structure and hierarchical pore system can provide ultra-high specific surface area and efficient mass transfer channels, creating favorable conditions for the construction of multi-metal active sites. Existing studies have shown that the electronic coupling effect between different metals in dual / triple-metal MOFs can significantly improve the catalytic activity and durability, but the phase separation phenomenon caused by random distribution of metal ratio seriously restricts the precise regulation and mechanism research of synergistic effect. Notably, High-Entropy MOFs (HEMOFs) as a new research direction is still in its infancy. The key to breaking this bottleneck lies in the development of multi-core MOF structures with high coordination number organic linkers. Although there are great challenges in converting functional MOFs into electrocatalysts with high activity and durability through rational design, such as topological structure collapse and active site embedding during pyrolysis, this strategy has irreplaceable scientific value in achieving precise construction of atomically dispersed multi-metal sites, which will provide a new paradigm for the development of new generation of efficient electrocatalytic materials. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a high-entropy framework material with a nanosheet array grown directionally on a porous metal substrate and its application; the high-entropy framework material contains a framework provided by multiple metal ions and ligands, providing guidance for the design of multi-metal framework materials.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] In a first aspect, the present application provides a multi-metal high-entropy framework material synthesized directionally on a porous substrate, which is synthesized by solvothermal synthesis of a high-entropy material with an array nanosheet structure from organic ligands and multiple metal ion salts, and is uniformly loaded on a metal porous carrier.

[0008] The present application prepares a multi-metal framework with ultrathin nanosheet structure by solvothermal synthesis. The nanosheet thickness distribution of the ultrathin nanosheet multi-metal framework is, for example, 0.5-50 nm, such as 1-3 nm, for example 1.3-3.5 nm; illustratively, its thickness can be 2.2 nm, 4.5 nm, 5.8 nm, 8.7 nm, 23.3 nm. Preferably, the average thickness of the nanosheet is 1-10 nm. In some embodiments, the synthesized high-entropy material with an array nanosheet structure is uniformly loaded on a metal foam carrier.

[0009] As an embodiment of the present application, the multi-metal high-entropy framework material of the present application contains five or more types of metal elements.

[0010] In a second aspect, the present application provides a method for preparing a multi-metallic high-entropy framework material synthesized on a porous substrate, the method comprising: placing a metal foam carrier in a precursor mixed solution containing an organic ligand and a plurality of metal ion salts for a solvothermal reaction; removing the metal foam carrier after the reaction, and washing and drying to obtain the multi-metallic high-entropy framework material.

[0011] As an embodiment of the present application, the organic ligand is selected from at least one of a carboxylic acid ligand and / or a fluorine-containing ligand.

[0012] As an embodiment of the present application, the carboxylic acid ligand is selected from 1,4-naphthalene dicarboxylic acid, 1,4-terephthalic acid, 2-amino terephthalic acid, 2,5-dihydroxy terephthalic acid, 1,3,5-tricarboxylic acid, 2,6-pyridine dicarboxylic acid, imidazole-4,5-dicarboxylic acid, and 3,4-pyridine dicarboxylic acid.

[0013] As an embodiment of the present application, the fluorine-containing ligand is selected from monofluoromethyl imidazole, difluoromethyl imidazole, trifluoromethyl imidazole, and 2-methyl-4-fluoro imidazole.

[0014] As an embodiment of the present application, the plurality of metal ion salts are selected from nitrate salts, chloride salts, sulfate salts, organic acid salts, organic salts, and hydrates thereof of nickel, silver, bismuth, iron, copper, zinc, vanadium, manganese, cobalt, aluminum, and chromium. Preferably, the plurality of metal ion salts are nitrate salts or chloride salts of the above transition metals. For example, nickel nitrate hexahydrate.

[0015] As an embodiment of the present application, the plurality of metal salts are in a near-equimolar ratio or an equimolar ratio.

[0016] As an embodiment of the present application, the precursor mixed solution containing the organic ligand and the plurality of metal ion salts is obtained by dissolving the organic ligand and the plurality of metal ion salts in an organic solvent, and growing the MOF precursor in a liquid phase reaction.

[0017] As an embodiment of the present application, the organic solvent comprises one or more of water, ethanol, methanol, and N,N-dimethylacetamide; the reaction temperature of the liquid phase reaction is 90-200°C, and the reaction time is 5-100 hours. In some embodiments, the plurality of metal salts are dissolved in water, ethanol, and DMF to form a mixed solution, and then the ligand is added to the mixed solution and magnetically stirred at a speed of 500-2000 rpm for 5-60 min. After the treatment, the mixed solution is transferred to an autoclave for material synthesis, and cooled to room temperature after the reaction. The material is obtained by uniformly transferring the solution into a centrifuge container, separating, and drying in an oven.

[0018] As an embodiment of the present application, the metal foam carrier is a metal foam carrier pre-treated by ultrasonic acid solution, removing surface oxide layer and organic matter; in some embodiments, the base material is treated by ultrasonic acid solution of 1M hydrochloric acid, and washed by deionized water and anhydrous ethanol for several times to remove surface oxide layer and organic matter.

[0019] As an embodiment of the present application, the cleaning is ultrasonic treatment of the metal foam carrier taken out after the reaction in ethanol (to remove unstable adhesives adhered to the surface layer), and then rinsing by deionized water and anhydrous ethanol.

[0020] As an embodiment of the present application, the temperature of the drying is 50-100℃, and the drying time is 10-200 hours.

[0021] As an embodiment of the present application, the reaction temperature of the solvothermal reaction is 80-180℃, and the reaction time is 3-50 hours. Preferably, the temperature of the solvothermal reaction is 100-180℃.

[0022] As a specific embodiment, a metal salt and an organic ligand are dissolved in an organic solvent, a MOF precursor is grown by liquid phase reaction, and then the mixture is poured into a 50ml autoclave. Subsequently, the autoclave is sealed and heated at high temperature for several hours. After cooling to room temperature, the obtained nickel foam is taken out and ultrasonically treated in ethanol. Finally, the synthesized material is washed by deionized water and ethanol for several times, and dried at 60℃ overnight.

[0023] In a third aspect, the multi-metallic high-entropy framework material, and the use of the multi-metallic high-entropy framework material prepared by the method of the present application also belong to the protection scope of the present application.

[0024] As an embodiment of the present application, the multi-metallic high-entropy framework material is used to construct an energy molecule and its related reaction and coupled energy storage and conversion system.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1) The present application prepares an energy material with a high-entropy framework structure by a solvothermal method, which not only realizes high-efficiency electrocatalysis, but also ensures the stability of the catalyst material;

[0027] 2) The electrocatalytic material provided by the present application has a multi-metallic framework structure, which not only greatly reduces the aggregation of metals, but also exposes more catalytically active sites, promotes electron conduction, and thus accelerates the reaction kinetics of catalysis;

[0028] 3) The electrocatalytic material provided by the application first loads multiple metals into a crystal structure, has low cost, simple operation, superior performance, and can achieve a large current density in a catalytic process, so that the material has a broad application prospect in the fields of energy conversion and energy storage. BRIEF DESCRIPTION OF DRAWINGS

[0029] Other features, objects, and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments, when read in conjunction with the accompanying drawings:

[0030] Figure 1 is the infrared spectrum of the ligand in Examples 1 and 2;

[0031] Figure 2 is the contact angle test chart of the material prepared in Example 1;

[0032] Figure 3 is the nickel positive ion distribution chart of the TOF-SIMS test of the material prepared in Example 1;

[0033] Figure 4 is the SEM chart of the material in Example 1;

[0034] Figure 5 is the AFM chart of the material in Example 2;

[0035] Figure 6 is the TEM chart of the material in Example 2. DETAILED DESCRIPTION

[0036] The application will be described in detail below with reference to the examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the application. These are within the scope of protection of the application.

[0037] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0038] The following gives five best embodiments of the application.

[0039] Example 1

[0040] The preparation of the nano-array high-entropy framework material on the porous metal substrate includes:

[0041] (1) Substrate pretreatment: Take a 20*30mm foam nickel and ultrasonically treat it with 1M hydrochloric acid solution for 10 minutes, and wash it with deionized water and anhydrous ethanol several times to remove the surface oxide layer and organic matter, then dry it in a 60°C oven for standby use.

[0042] (2) Synthesis of high-entropy framework: The self-supported high-entropy electrode was prepared by solvothermal method. Typically, 2.5 mmol of terephthalic acid and 0.5 mmol of MnCl2·4H2O, 0.5 mmol of FeCl3·6H2O, 0.5 mmol of CoCl2·6H2O, 0.5 mmol of NiCl2·6H2O and 0.5 mmol of ZnCl2·6H2O were dissolved in mixed solvents containing DMF, anhydrous ethanol and H2O. Then it was completely dissolved by magnetic stirring.

[0043] (3) Hydrothermal reaction: A piece of pretreated foam nickel was placed in a 25 ml polytetrafluoro liner, and the above mixed solution was hydrothermally reacted at 120°C for 24 h.

[0044] (4) Sample post-processing: After the reaction was completed, the synthesized material was washed with deionized water and anhydrous ethanol and ultrasonicated for 5 minutes to remove the unstable adhesives adhered to the surface layer, and then dried at 60°C for 12 h.

[0045] Characterization of the high-entropy framework material grown directionally on the porous metal substrate: Figure 1 is the infrared spectrum of the ligand in step 2, Figure 2 and Figure 3 is the contact angle test of the sample prepared in Example 1 and the TOF-SIMS test of the sample, respectively, and the nickel positive ion distribution map. Figure 4 is the SEM image of the sample prepared in Example 1, further verifying the prepared directional array framework material.

[0046] Example 2

[0047] Preparation of powder nanometer high-entropy framework material, the preparation process includes:

[0048] (1) Synthesis of high-entropy framework: The powder high-entropy framework material was prepared by solvothermal method. Typically, 2.5 mmol of terephthalic acid and 0.5 mmol of MnCl2·4H2O, 0.5 mmol of FeCl3·6H2O, 0.5 mmol of CoCl2·6H2O, 0.5 mmol of NiCl2·6H2O and 0.5 mmol of ZnCl2·6H2O were dissolved in mixed solvents containing DMF, anhydrous ethanol and H2O. Then it was completely dissolved by magnetic stirring.

[0049] (2) Hydrothermal reaction: The above mixed solution was hydrothermally reacted at 120°C for 24 h in a 25 ml polytetrafluoro liner.

[0050] (3) Sample post-processing: After the reaction was completed, the synthesized material was washed with deionized water and anhydrous ethanol and ultrasonicated for 5 minutes to remove the unstable adhesives adhered to the surface layer, and then dried at 60°C for 12 h.

[0051] Characterization of powder nanohigh-entropy framework materials: Figure 5 and Figure 6 are AFM and TEM images of the prepared high-entropy framework, respectively. As can be seen from the images, the framework is of nanosheet structure.

[0052] Example 3

[0053] A fluorinated modified nanohigh-entropy framework material was prepared, the preparation of which included:

[0054] (1) Synthesis of fluorinated modified high-entropy framework: A powder fluorinated high-entropy framework material was prepared by a solvothermal method. Typically, 1.5 mmol of imidazole-4,5-dicarboxylic acid, 1.0 mmol of 2-methyl-4-fluoroimidazole, and 0.5 mmol of MnCl2·4H2O, 0.5 mmol of FeCl3·6H2O, 0.5 mmol of CoCl2·6H2O, 0.5 mmol of NiCl2·6H2O, and 0.5 mmol of ZnCl2·6H2O were dissolved in a mixed solvent containing DMF, anhydrous ethanol, and H2O. Then it was completely dissolved by magnetic stirring.

[0055] (2) Hydrothermal reaction: The above mixture was added to a 25 ml Teflon-lined autoclave and hydrothermally reacted at 100°C for 12 h.

[0056] (3) Sample post-treatment: After the reaction was completed, the synthesized material was washed with deionized water and anhydrous ethanol and ultrasonicated for 5 minutes to remove incompletely reacted substances, and then dried at 60°C for 12 h.

[0057] Example 4

[0058] (1) Substrate pretreatment, the same as step (1) in Example 1.

[0059] (2) Synthesis of high-entropy framework: A powder high-entropy framework material was prepared by a solvothermal method. Typically, 5 mmol of trimesic acid and 1.0 mmol of MnCl2·4H2O, 1.0 mmol of FeCl3·6H2O, 1.0 mmol of CoCl2·6H2O, 1.0 mmol of NiCl2·6H2O, and 1.0 mmol of ZnCl2·6H2O were dissolved in a mixed solvent containing DMF and anhydrous ethanol. Then it was completely dissolved by magnetic stirring.

[0060] The mixture was then poured into a 50 ml Teflon-lined autoclave, and a pretreated NF was immersed therein. Subsequently, the autoclave was sealed and heated at 120°C for 24 h. After cooling to room temperature, the resulting nickel foam was taken out and ultrasonicated in ethanol for 5 min. Finally, the synthesized material was washed several times with deionized water and ethanol, and dried at 60°C overnight.

[0061] Example 5

[0062] Applications in energy storage and conversion

[0063] (1) Electrochemical performance test of high-entropy framework structure electrode. The prepared material is used for characterization test of electrochemical performance.

[0064] (2) The high-entropy framework structure material can significantly improve the cycle life of the electrode and the ion transport kinetics due to its multi-element active site and structural buffering capacity in the field of electrochemical energy storage.

[0065] The specific embodiments of the application are described above. It should be understood that the application is not limited to the specific implementation described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the application.

Claims

1. A multi-metal high-entropy framework material directionally synthesized on a porous substrate, characterized in that, The material is a high-entropy material with an array of nanosheets synthesized by solvothermal synthesis of organic ligands and various metal ion salts, and uniformly loaded onto a porous metal support.

2. The multi-metal high-entropy framework material according to claim 1, characterized in that, The thickness of the nanosheet is 0.5 to 50 nanometers.

3. The multi-metal high-entropy framework material according to claim 1 or 2, characterized in that, It contains five or more kinds of metallic elements.

4. A method for preparing a multi-metal high-entropy framework material directionally synthesized on a porous substrate as described in claim 1, characterized in that, The method includes: placing a metal foam carrier in a precursor mixture containing organic ligands and multiple metal ion salts for a solvothermal reaction; after the reaction is completed, removing the metal foam carrier, cleaning and drying it to obtain the multi-metal high-entropy framework material.

5. The preparation method according to claim 4, characterized in that, The organic ligand is selected from at least one of carboxylic acid ligands and / or fluorine-containing ligands; The carboxylic acid ligand is selected from 1,4-naphthalenedicarboxylic acid, 1,4-terephthalic acid, 2-aminoterephthalic acid, 2,5-dihydroxyterephthalic acid, 1,3,5-pyromellitic acid, 2,6-pyridinedicarboxylic acid, imidazole-4,5-dicarboxylic acid, and 3,4-pyridinedicarboxylic acid. The fluorinated ligand is selected from monofluoromethylimidazole, difluoromethylimidazole, trifluoromethylimidazole, and 2-methyl-4-fluoroimidazole.

6. The preparation method according to claim 4, characterized in that, The various metal ion salts are selected from nitrates, chlorides, sulfates, organic acid salts, organic salts and their hydrates of nickel, silver, bismuth, iron, copper, zinc, vanadium, manganese, cobalt, aluminum and chromium; the various metal salts are in near equimolar ratio or equimolar ratio.

7. The preparation method according to claim 4, characterized in that, The precursor mixture containing organic ligands and multiple metal ion salts is obtained by dissolving the organic ligands and multiple metal ion salts in an organic solvent and growing MOF precursors by liquid-phase reaction; the organic solvent includes one or more of water, ethanol, methanol, and N,N-dimethylacetamide; the reaction temperature of the liquid-phase reaction is 90-200℃ and the reaction time is 5-100 hours.

8. The preparation method according to claim 4, characterized in that, It also includes at least one of the following technical features; A1. The metal foam carrier is a metal foam carrier that has undergone ultrasonic pretreatment with acid solution to remove the surface oxide layer and organic matter; A2. The cleaning process involves ultrasonically treating the metal foam carrier removed after the reaction in ethanol, followed by rinsing with deionized water and anhydrous ethanol. A3. The drying temperature is 50-100℃, and the drying time is 10-200 hours.

9. The preparation method according to claim 4, characterized in that, The solvothermal reaction is carried out at a temperature of 80-180℃ for 3-50 hours.

10. The use of a multimetallic high-entropy framework material as described in any one of claims 1-3, or a multimetallic high-entropy framework material prepared by the method described in any one of claims 4-9, characterized in that, The multimetallic high-entropy framework material is used to construct an energy storage and conversion system for energy molecules and their related reactions and couplings.

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