High-entropy carbide nanofiber membrane, and preparation method and application thereof

Abstract

The application discloses a high-entropy carbide nanofiber membrane and a preparation method and application thereof, and belongs to the technical field of inorganic non-metallic fiber materials and electromagnetic shielding materials. The preparation method is as follows: PAN and anhydrous DMF are mixed to prepare a PAN solution; equal-molar-ratio multiple metal halide precursors are mixed to prepare total metal halides; citric acid and the first portion of DMF are sequentially added to the total metal halides, and then the mixture is stirred in an ice bath until uniform, forming a multi-metal precursor mother liquor; the second portion of DMF is added and the stirring is continued until no precipitate is generated, thereby preparing a multi-metal precursor solution; the PAN solution and the multi-metal precursor solution are mixed to prepare a spinning solution; the spinning solution is subjected to electrostatic spinning treatment to prepare a precursor fiber membrane; and the precursor fiber membrane is sequentially subjected to pre-oxidation stabilization treatment, carbonization treatment and carbon thermal reduction reaction to prepare the high-entropy carbide nanofiber membrane. The application solves the problems of large density, poor flexibility, insufficient shielding efficiency under thin layer conditions and the like of the existing electromagnetic shielding materials.

Description

Technical Field

[0001] This invention belongs to the technical field of inorganic non-metallic fiber materials and electromagnetic shielding materials, specifically relating to a high-entropy carbide nanofiber membrane, its preparation method, and its application. Background Technology

[0002] With the development of 5G communication, radar systems, wearable electronics, and high-density integrated electronic devices, electromagnetic radiation and electromagnetic interference problems are becoming increasingly prominent. Electromagnetic shielding materials can weaken the propagation of electromagnetic waves through mechanisms such as reflection and absorption, thereby improving the electromagnetic compatibility and safety of electronic devices. Although traditional metal shielding materials have high shielding effectiveness, they suffer from problems such as high density, susceptibility to corrosion, and limitations in processing and shaping; polymer-based conductive composite materials are lightweight and easy to process, but their temperature resistance and long-term stability are limited.

[0003] High-entropy carbides, as novel multi-principal ceramic materials, possess characteristics such as high melting point, high hardness, corrosion resistance, and certain electrical conductivity, making them potential electromagnetic shielding materials for high-temperature environments. However, existing high-entropy carbides are mostly prepared in bulk or powder form, making it difficult to obtain flexible thin-film structures. Furthermore, multi-metal systems are prone to problems such as solubility differences, local separation, and uneven phase formation in the precursor solution stage, resulting in insufficient material performance repeatability. In addition, bulk ceramics are generally difficult to form and process, which is not conducive to achieving lightweight electromagnetic shielding in complex-shaped devices, and the shielding effectiveness is insufficient under thin-layer conditions.

[0004] Therefore, there is an urgent need for a process-controllable, scalable method for preparing multi-principal-element high-entropy carbide materials with continuous film structures, so as to achieve film materials that balance high-temperature stability and electromagnetic shielding performance. Summary of the Invention

[0005] To address the common problems of high density, poor flexibility, and insufficient shielding effectiveness under thin-layer conditions in existing electromagnetic shielding materials, this invention provides a high-entropy carbide fiber cloth prepared by electrospinning, its preparation method, and its application. This material can still have high electromagnetic shielding performance with a small thickness, while also being lightweight, flexible, and stable.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing high-entropy carbide nanofiber membranes, comprising the following steps: A PAN solution was prepared by mixing PAN and anhydrous DMF. A total metal halide was prepared by mixing multiple metal halide precursors in equimolar ratio; citric acid and the first part of DMF were added to the total metal halide in sequence, and then the mixture was stirred in an ice bath until homogeneous to form a multi-metal precursor mother liquor. The second part of DMF was then added and stirred until no precipitate was found to prepare a multi-metal precursor solution. A PAN solution and a multi-metal precursor solution were mixed to prepare a spinning solution. The spinning solution was then used for electrospinning to obtain a precursor fiber membrane. The precursor fiber membrane was subjected to pre-oxidation stabilization treatment to obtain the pre-oxidized fiber membrane. The pre-oxidized fiber membrane was subjected to carbonization and carbothermal reduction reaction in sequence to obtain a high-entropy carbide nanofiber membrane.

[0007] In one embodiment, the mass ratio of PAN to anhydrous DMF is 1:(7~10).

[0008] In one embodiment, the metal halide precursor is a variety of TiCl4, ZrCl4, HfCl4, TaCl5, NbCl5, VCl3, MoCl5, CrCl3, and WCl3; the molar ratio of the total metal halide, citric acid, and the first DMF is 1:(0.2~0.5):(2~3); the temperature of the ice bath is 0℃~5℃; and the molar ratio of the total metal halide and the second DMF is 1:(4~6).

[0009] In one embodiment, the volume ratio of the PAN solution to the multi-metal precursor solution is 1:3.

[0010] In one embodiment, the conditions for the electrospinning process are: voltage 15 kV~20 kV, distance from needle to receiver 5 cm~10 cm, feed pump flow rate 0.001 mL / min~0.002 mL / min, and roller speed 100 r / min~200 r / min.

[0011] In one embodiment, the pre-oxidation stabilization treatment process is as follows: The precursor fiber membrane was placed in an air atmosphere in a muffle furnace and heated from room temperature to 200℃ at a heating rate of 2℃ / min, and then heated from 200℃ to 240℃~280℃ at a heating rate of 1℃ / min, and held at 240℃~280℃ for 2h~3h.

[0012] In one embodiment, the carbonization process is as follows: The pre-oxidized fiber membrane was heat-treated in an inert atmosphere, with the temperature increased from room temperature to 600 ℃ at a rate of 5 ℃ / min, and then increased from 600 ℃ to 900 ℃ at a rate of 3 ℃ / min and held for 2 h to 3 h. The process of the carbothermic reduction reaction is as follows: The carbonized fiber membrane was placed in an inert atmosphere and heated from 900 ℃ to 1400 ℃~1600 ℃ at a heating rate of 3 ℃ / min and held for 2 h~3 h to obtain a high-entropy carbide nanofiber membrane.

[0013] In one embodiment, the high-entropy carbide in the high-entropy carbide nanofiber membrane is a (TiZrHfNbTa)C solid solution.

[0014] The present invention also provides a high-entropy carbide nanofiber membrane prepared by the above-described method, wherein the high-entropy carbide nanofiber membrane has a three-dimensional fiber network structure; and the average electromagnetic shielding effectiveness of the high-entropy carbide nanofiber membrane is 60dB under the condition of a stack thickness of 0.5mm.

[0015] The present invention also provides an application of a high-entropy carbide nanofiber membrane prepared by the above-described method in electromagnetic shielding.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing high-entropy carbide nanofiber membranes. The method uses polyacrylonitrile (PAN) as a spinnable carrier and carbon source, N,N-dimethylformamide (DMF) as a solvent, employs a multi-metal halide precursor and introduces a complexing agent to improve the dispersion and uniformity of the multi-metals in the spinning solution, obtains the precursor fiber membrane by electrospinning, and then obtains a flexible high-entropy carbide nanofiber membrane through pre-oxidation stabilization, carbonization under an inert atmosphere and carbothermal reduction treatment. Equimolar (or near-equimolar) multimetallic precursors are more likely to form single-phase / main-phase high-entropy solid solution carbides after carbonization, improving compositional uniformity and repeatability. Using multimetallic precursors and citric acid complexing agents, a uniform high-entropy carbide phase can be formed at high temperatures, maintaining a stable three-dimensional fiber structure after carbonization. The porous three-dimensional high-entropy fiber structure is prepared by electrospinning, overcoming the problem of excessive density in traditional shielding materials. Pre-oxidation stabilization allows PAN fibers to be formed first, maintaining a continuous film structure and improving carbon yield during subsequent high-temperature carbonization / carbothermal reduction. Carbonization provides a carbon source and framework for subsequent reactions, while carbothermal reduction can transform the multimetallic precursor into the target high-entropy carbide phase at high temperatures. At the same time, the carbon framework is used to achieve in-situ reaction, reduce sintering densification, and retain the porous fiber structure to achieve lightweight electromagnetic shielding.

[0017] Furthermore, this invention provides for the first time a method for preparing electrospun fiber membranes of high-entropy carbides. The process is controllable and easily scaled up, applicable to high-entropy carbide systems with different metal compositions. The material system can be expanded simply by changing the type and ratio of the metal salt. This invention's method is process-controllable and scalable to ternary / quaternary and higher-level multi-principal-element carbide systems with different metal combinations, making it suitable for fields such as electronic devices, electromagnetic compatibility, and electromagnetic protection.

[0018] This invention also provides a method for preparing a three-dimensional fiber network high-entropy carbide nanofiber membrane. The resulting membrane has a porous fiber network structure, can be continuously self-supported or stacked, and has characteristics of both conductive and ceramic phases. The fiber diameter is uniform and the membrane is flexible. It not only has good electromagnetic shielding performance, but also, in X-band (8.2-12.4 GHz) testing, the average electromagnetic shielding effectiveness of samples with a stack thickness of about 0.5 mm is about 60 dB. Furthermore, it can reduce secondary electromagnetic pollution while ensuring high shielding effectiveness. Attached Figure Description

[0019] Figure 1 The XRD pattern of the (TiZrHfNbTa)C nanofiber membrane after heat treatment in the example is shown. Figure 2 The image shown is a SEM image of the (TiZrHfNbTa)C nanofiber membrane after heat treatment in the example. Figure 3 This is a schematic diagram of the bending state of the (TiZrHfNbTa)C nanofiber membrane in the example; Figure 4 This is a schematic diagram of the electromagnetic shielding performance test results of the (TiZrHfNbTa)C nanofiber membrane in the example (SE). T SE A with SE R ). Detailed Implementation

[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0022] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0023] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0024] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0025] In recent years, electromagnetic radiation and electromagnetic interference have become increasingly prominent issues. Electromagnetic shielding materials can attenuate incident electromagnetic waves through mechanisms such as reflection and absorption, thereby reducing electromagnetic interference to electronic devices and systems and improving electromagnetic compatibility. To meet the demands for lightweight, high-temperature resistant, and complex-shaped device integration, shielding materials with film-forming properties and structural designability have attracted attention.

[0026] High-entropy carbides, as novel multi-principal-element ceramic materials, possess characteristics such as high melting point, corrosion resistance, wear resistance, and certain electrical conductivity, making them potential materials for electromagnetic protection in high-temperature environments. However, existing high-entropy carbides are mostly prepared in bulk or powder form, making it difficult to obtain continuous, stackable film structures.

[0027] Based on this, this application proposes a technical route for constructing nanofiber membranes from multi-principal high-entropy carbide materials. Continuous fiber membrane formation is achieved through electrospinning, combined with pre-oxidation stabilization and staged heat treatment under an inert atmosphere. This process carbonizes the polymer and induces a carbothermal reduction reaction, generating multi-principal carbide phases in situ at the fiber scale while maintaining the porous fiber network structure. The resulting membrane can be used directly as an electromagnetic shielding layer or laminated to meet different thickness and shielding effectiveness requirements, making it suitable for electromagnetic compatibility and electromagnetic protection applications in electronic devices.

[0028] This invention provides a multi-principal-component high-entropy carbide nanofiber membrane, its preparation method, and its application.

[0029] On the one hand, a method for preparing a multi-principal-element high-entropy carbide nanofiber membrane is provided. A continuous nanofiber membrane is prepared by electrospinning, and carbonization and carbothermic reduction are achieved during pre-oxidation stabilization and staged heat treatment in an inert atmosphere, thereby obtaining a multi-principal-element high-entropy carbide nanofiber membrane. The membrane can be used for electromagnetic shielding, and specifically includes the following steps: Step 1: Preparation of PAN solution. Mix PAN (average molecular weight about 150,000) with anhydrous DMF at a mass ratio of 1:(7~10) and stir magnetically at 50℃ for 2~4 h to obtain a uniform and transparent PAN solution.

[0030] Step 2: Preparation of the multi-metal precursor solution. Weigh equimolar amounts of metal halide precursors (such as TiCl4, ZrCl4, HfCl4, TaCl5, NbCl5, VCl3, MoCl5, CrCl3, WCl3, etc.) in a glove box or an anhydrous inert environment to obtain total metal halides. Add citric acid and DMF sequentially to the total metal halide in a molar ratio of total metal halide:citric acid:DMF of 1:0.2~0.5:2~3. Then mix and stir in an ice bath at 0℃~5℃ until homogeneous to form a multi-metal precursor mother liquor. Add additional DMF (the molar ratio of total metal halide to the second part of DMF is 1:(4~6)) and continue stirring until no precipitate is formed to obtain the multi-metal precursor solution.

[0031] Step 3: Preparation of spinning solution. The PAN solution obtained in Step 1 is poured into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stirred at room temperature for 12-24 h to obtain a homogeneous spinning solution.

[0032] Step 4: Electrospinning process. The spinning solution is electrospinned under the following conditions: voltage 15~20 kV, needle-to-receiver distance 5~10 cm, feed pump flow rate 0.001~0.002 mL / min, and roller speed 100~200 r / min, to obtain precursor fiber membrane.

[0033] Step 5: Pre-oxidation stabilization. Place the precursor fiber membrane in an air atmosphere in a muffle furnace, raise the temperature from room temperature to 200 ℃ (heating rate of 2 ℃ / min); raise the temperature from 200 ℃ to 240~280 ℃ (heating rate of 1 ℃ / min); and hold at 240~280 ℃ for 2~3 h.

[0034] Step 6: Carbonization and carbothermic reduction reaction. The pre-oxidized fiber membrane was heat-treated in an inert atmosphere: the temperature was raised from room temperature to 600 ℃ (heating rate of 5 ℃ / min); the temperature was raised from 600 ℃ to 900 ℃ (heating rate of 3 ℃ / min) and held for 2~3 h; then the temperature was raised to 1400~1600 ℃ (heating rate of 3 ℃ / min) and held for 2~3 h to obtain a high-entropy carbide nanofiber membrane.

[0035] The high-entropy carbide is preferably a (TiZrHfNbTa)C solid solution.

[0036] On the other hand, a high-entropy carbide nanofiber membrane prepared by the above-described method is also provided, wherein the high-entropy carbide nanofiber membrane has a three-dimensional fiber network structure.

[0037] Furthermore, this paper also provides an application of high-entropy carbide nanofiber membranes prepared using the aforementioned method in electromagnetic shielding. For example... Figure 4 As shown, the high-entropy carbide film (0.5 mm) represented by (TiZrHfNbTa)C prepared in this invention has an average shielding effectiveness of about 60 dB in the X-band (8.2-12.4 GHz), indicating that it has excellent electromagnetic shielding performance.

[0038] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0040] Example 1: Step 1: Mix 10 g of PAN (average molecular weight approximately 150,000) with 80 g of anhydrous DMF and stir magnetically at 50°C for 2 h to obtain a uniform and transparent PAN solution.

[0041] Step 2: Weigh equimolar amounts of 1.89 g TiCl4, 2.33 g ZrCl4, 3.20 g HfCl4, 3.58 g TaCl5, and 2.70 g NbCl5 metal halide precursors in a glove box. Add 4 g citric acid and 10 g DMF sequentially, then mix and stir in an ice bath until homogeneous to form a multi-metal precursor mother liquor. Add 20 g DMF and continue stirring until no precipitate forms.

[0042] Step 3: Pour the PAN solution obtained in Step 1 into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stir at room temperature for 24 h to obtain a uniform spinning solution.

[0043] Step 4: Electrospin the spinning solution under the conditions of 18 kV voltage, 6 cm distance from needle to receiver, 0.001 mL / min feed pump flow rate, and 100 r / min drum speed to obtain precursor fiber membrane.

[0044] Step 5: Place the precursor fiber membrane in an air atmosphere in a muffle furnace and raise the temperature to 200 ℃ (heating rate of 2 ℃ / min); raise the temperature from 200 ℃ to 280 ℃ (heating rate of 1 ℃ / min); and hold at 280 ℃ for 2~3 h.

[0045] Step 6: Heat-treat the pre-oxidized fiber membrane in an inert atmosphere: raise the temperature from room temperature to 600 ℃ (heating rate of 5 ℃ / min); raise the temperature from 600 ℃ to 900 ℃ (heating rate of 3 ℃ / min) and hold for 2 h; then raise the temperature to 1500 ℃ (heating rate of 3 ℃ / min) and hold for 3 h to obtain (TiZrHfNbTa)C nanofiber membrane.

[0046] The XRD pattern of the (TiZrHfNbTa)C nanofiber membrane obtained in this embodiment is as follows: Figure 1 As shown, no other impurities are present. The fiber diameter is uniform, approximately 300 nm (e.g., Figure 2 As shown), and has flexibility (such as...). Figure 3 As shown), it is an excellent electromagnetic shielding material (such as...) Figure 4 (As shown).

[0047] Example 2: Step 1: Mix 10 g of PAN (average molecular weight approximately 150,000) with 70 g of anhydrous DMF and stir magnetically at 50°C for 2 h to obtain a uniform and transparent PAN solution.

[0048] Step 2: Weigh equimolar amounts of 1.89 g TiCl4, 2.33 g ZrCl4, 3.20 g HfCl4, 3.58 g TaCl5, and 2.70 g NbCl5 metal halide precursors in a glove box. Add 1.96 g citric acid and 7.31 g DMF sequentially, then mix and stir in an ice bath until homogeneous to form a multi-metal precursor mother liquor. Add 20 g DMF and continue stirring until no precipitate forms.

[0049] Step 3: Pour the PAN solution obtained in Step 1 into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stir at room temperature for 12 h to obtain a uniform spinning solution.

[0050] Step 4: Electrospin the spinning solution under the conditions of 15 kV voltage, 5 cm distance from needle to receiver, 0.001 mL / min feed pump flow rate, and 100 r / min drum speed to obtain precursor fiber membrane.

[0051] Step 5: Place the precursor fiber membrane in an air atmosphere in a muffle furnace and raise the temperature to 200 ℃ (heating rate of 2 ℃ / min); raise the temperature from 200 ℃ to 240 ℃ (heating rate of 1 ℃ / min); and keep it at 240 ℃ for 2~3 h.

[0052] Step 6: Heat-treat the pre-oxidized fiber membrane in an inert atmosphere: raise the temperature from room temperature to 600 ℃ (heating rate of 5 ℃ / min); raise the temperature from 600 ℃ to 900 ℃ (heating rate of 3 ℃ / min) and hold for 2 h; then raise the temperature to 1400 ℃ (heating rate of 3 ℃ / min) and hold for 3 h to obtain (TiZrHfNbTa)C nanofiber membrane.

[0053] Example 3: Step 1: Mix 10 g of PAN (average molecular weight approximately 150,000) with 100 g of anhydrous DMF and stir magnetically at 50°C for 4 h to obtain a uniform and transparent PAN solution.

[0054] Step 2: Weigh 1.89 g TiCl4, 2.33 g ZrCl4, 3.20 g HfCl4, 3.58 g TaCl5, and 2.70 g NbCl5 metal halide precursors in an equimolar ratio in a glove box. Add 4.75 g citric acid and 10.95 g DMF sequentially, then mix and stir in an ice bath until homogeneous to form a multi-metal precursor mother liquor. Add 20 g DMF and continue stirring until no precipitate forms.

[0055] Step 3: Pour the PAN solution obtained in Step 1 into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stir at room temperature for 24 h to obtain a uniform spinning solution.

[0056] Step 4: Electrospin the spinning solution under the conditions of 20 kV voltage, 10 cm distance from needle to receiver, 0.002 mL / min feed pump flow rate, and 200 r / min drum speed to obtain precursor fiber membrane.

[0057] Step 5: Place the precursor fiber membrane in an air atmosphere in a muffle furnace and raise the temperature to 200 ℃ (heating rate of 2 ℃ / min); raise the temperature from 200 ℃ to 280 ℃ (heating rate of 1 ℃ / min); and hold at 280 ℃ for 2~3 h.

[0058] Step 6: Heat-treat the pre-oxidized fiber membrane in an inert atmosphere: raise the temperature from room temperature to 600 ℃ (heating rate of 5 ℃ / min); raise the temperature from 600 ℃ to 900 ℃ (heating rate of 3 ℃ / min) and hold for 2 h; then raise the temperature to 1600 ℃ (heating rate of 3 ℃ / min) and hold for 3 h to obtain (TiZrHfNbTa)C nanofiber membrane.

[0059] Comparative Example 1: Citric acid without the complexing agent Step 1: Mix 10 g of PAN (average molecular weight approximately 150,000) with 80 g of anhydrous DMF and stir magnetically at 50°C for 2 h to obtain a uniform and transparent PAN solution.

[0060] Step 2: Weigh equimolar amounts of 1.89 g TiCl4, 2.33 g ZrCl4, 3.20 g HfCl4, 3.58 g TaCl5, and 2.70 g NbCl5 metal halide precursors in a glove box. Add 10 g DMF and mix in an ice bath until homogeneous to form a multi-metal precursor mother liquor. Then add 20 g DMF and continue stirring. Precipitation was observed.

[0061] Step 3: Pour the PAN solution obtained in Step 1 into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stir at room temperature for 24 h to obtain the spinning solution.

[0062] Step 4: Electrospinning was performed on the spinning solution under the conditions of 18 kV voltage, 6 cm distance from needle to receiver, 0.001 mL / min feed pump flow rate, and 100 r / min drum speed. It was found that the Taylor cone formed during the spinning process was unstable and dripped, and the spinning failed.

[0063] Comparative Example 2: No pre-oxidation treatment performed Step 1: Mix 10 g of PAN (average molecular weight approximately 150,000) with 80 g of anhydrous DMF and stir magnetically at 50°C for 2 h to obtain a uniform and transparent PAN solution.

[0064] Step 2: Weigh equimolar amounts of 1.89 g TiCl4, 2.33 g ZrCl4, 3.20 g HfCl4, 3.58 g TaCl5, and 2.70 g NbCl5 metal halide precursors in a glove box. Add 4 g citric acid and 10 g DMF sequentially, then mix and stir in an ice bath until homogeneous to form a multi-metal precursor mother liquor. Add 20 g DMF and continue stirring until no precipitate forms.

[0065] Step 3: Pour the PAN solution obtained in Step 1 into the multi-metal precursor solution obtained in Step 2 at a volume ratio of 1:3, and stir at room temperature for 24 h to obtain a uniform spinning solution.

[0066] Step 4: Electrospin the spinning solution under the conditions of 18 kV voltage, 6 cm distance from needle to receiver, 0.001 mL / min feed pump flow rate, and 100 r / min drum speed to obtain precursor fiber membrane.

[0067] Step 5: Heat-treat the precursor fiber membrane in an inert atmosphere: raise the temperature from room temperature to 600 ℃ (heating rate of 5 ℃ / min); raise the temperature from 600 ℃ to 900 ℃ (heating rate of 3 ℃ / min) and hold for 2 h; then raise the temperature to 1500 ℃ (heating rate of 3 ℃ / min) and hold for 3 h, resulting in a (TiZrHfNbTa)C nanofiber membrane with cracks and pores.

[0068] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for preparing a high-entropy carbide nanofiber membrane, characterized in that, Includes the following steps: A PAN solution was prepared by mixing PAN and anhydrous DMF. A total metal halide was prepared by mixing multiple metal halide precursors in equimolar ratio; citric acid and the first part of DMF were added to the total metal halide in sequence, and then the mixture was stirred in an ice bath until homogeneous to form a multi-metal precursor mother liquor. The second part of DMF was then added and stirred until no precipitate was found to prepare a multi-metal precursor solution. A PAN solution and a multi-metal precursor solution were mixed to prepare a spinning solution. The spinning solution was then used for electrospinning to obtain a precursor fiber membrane. The precursor fiber membrane was subjected to pre-oxidation stabilization treatment to obtain the pre-oxidized fiber membrane. The pre-oxidized fiber membrane was subjected to carbonization and carbothermal reduction reaction in sequence to obtain a high-entropy carbide nanofiber membrane.

2. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The mass ratio of PAN to anhydrous DMF is 1:(7~10).

3. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The metal halide precursor is a variety of TiCl4, ZrCl4, HfCl4, TaCl5, NbCl5, VCl3, MoCl5, CrCl3, and WCl3; the molar ratio of the total metal halide, citric acid, and the first DMF is 1:(0.2~0.5):(2~3); the temperature of the ice bath is 0℃~5℃; and the molar ratio of the total metal halide and the second DMF is 1:(4~6).

4. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The volume ratio of the PAN solution to the multi-metal precursor solution is 1:

3.

5. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The conditions for the electrospinning process are: voltage 15 kV~20 kV, distance from needle to receiver 5 cm~10 cm, feed pump flow rate 0.001 mL / min~0.002 mL / min, and roller speed 100 r / min~200 r / min.

6. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The pre-oxidation stabilization treatment process is as follows: The precursor fiber membrane was placed in an air atmosphere in a muffle furnace and heated from room temperature to 200 ℃ at a heating rate of 2 ℃ / min, and then heated from 200 ℃ to 240 ℃~280 ℃ at a heating rate of 1 ℃ / min, and held at 240 ℃~280 ℃ for 2 h~3 h.

7. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The carbonization process is as follows: The pre-oxidized fiber membrane was heat-treated in an inert atmosphere, with the temperature increased from room temperature to 600℃ at a rate of 5℃ / min, and then increased from 600℃ to 900℃ at a rate of 3℃ / min and held for 2 h to 3 h. The process of the carbothermic reduction reaction is as follows: The carbonized fiber membrane was placed in an inert atmosphere and heated from 900 ℃ to 1400 ℃~1600 ℃ at a heating rate of 3 ℃ / min and held for 2 h~3 h to obtain a high-entropy carbide nanofiber membrane.

8. The method for preparing a high-entropy carbide nanofiber membrane according to claim 1, characterized in that, The high-entropy carbide in the high-entropy carbide nanofiber membrane is a (TiZrHfNbTa)C solid solution.

9. A high-entropy carbide nanofiber membrane, characterized in that, The high-entropy carbide nanofiber membrane was prepared by the preparation method according to any one of claims 1 to 8. The high-entropy carbide nanofiber membrane has a three-dimensional fiber network structure. Under the condition of a stack thickness of 0.5 mm, the average electromagnetic shielding effectiveness of the high-entropy carbide nanofiber membrane is 60 dB.

10. The application of a high-entropy carbide nanofiber membrane in electromagnetic shielding, characterized in that, The high-entropy carbide nanofiber membrane was prepared using the method described in any one of claims 1 to 8.

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