Preparation of hollow cubic cofebmnncu high-entropy alloy / carbon composite nanomaterials and its electromagnetic wave absorption application

Abstract

This invention belongs to the field of magnetic electromagnetic wave absorbing materials technology, specifically relating to the preparation and electromagnetic wave absorption application of hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials. Using cubic ZIF-67 as a self-sacrificing template, this invention introduces multiple metal ions such as Fe, Ni, Mn, and Cu into its framework structure through multi-element ion exchange. Utilizing ligand competition-induced synchronous etching and metal ion co-precipitation, a surface-wrinkled high-entropy metal hydroxide hollow nanocube with good morphological inheritance is prepared. After subsequent heat treatment, the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial is finally obtained. This invention features a simple process, low equipment requirements, and outstanding environmental friendliness. The resulting composite nanomaterial achieves excellent electromagnetic wave absorption performance at a relatively thin thickness, providing a novel technical approach for the simplified development and large-scale application of lightweight and efficient microwave absorbing materials.

Description

Technical Field

[0001] This invention belongs to the field of magnetic electromagnetic wave absorbing materials technology, specifically relating to the preparation of hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials and their electromagnetic wave absorption applications. Background Technology

[0002] Currently, information technology is reshaping human society at an unprecedented pace. New-generation technological infrastructure, represented by 5G / 6G mobile communications, the Internet of Things, and artificial intelligence, has become a core engine driving social progress. However, with the accelerating pace of digitalization, the resulting electromagnetic radiation and signal interference problems are becoming increasingly prominent, forming new types of pollution. Against this backdrop, developing advanced absorbing materials that can efficiently control and absorb electromagnetic wave energy has become a key technological requirement for ensuring the sustainable development of the electronics and information industry and building a clean electromagnetic environment.

[0003] Traditional electromagnetic attenuation materials such as ferrites and magnetic metals often require significant thickness to achieve strong absorption, sacrificing the lightweight and integrated characteristics of the devices. Furthermore, their effective operating frequency bands are often limited to specific ranges, making it difficult to match the ever-expanding spectrum demands of future communication technologies. These bottlenecks severely restrict their application potential in mid-to-high frequency, broadband, and harsh environments.

[0004] Carbon materials, as a class of dielectric absorbing materials, possess advantages such as low density (beneficial for lightweight devices), tunable conductivity, and abundant defect structures, exhibiting excellent dielectric loss performance. Furthermore, by controlling the microstructures such as porous and hollow structures, or by combining them with magnetic metal particles, impedance matching and loss capability can be synergistically optimized. However, the composite effect of a single magnetic metal and carbon material is still insufficient, and the current preparation of porous and hollow structures mostly relies on hard template methods, requiring acid and alkali etching to remove the template, which involves cumbersome synthesis steps and can easily cause environmental pollution. Therefore, how to design and improve the microwave absorption performance of magnetic metal / carbon composite materials through a simplified synthesis process has become a key problem that urgently needs to be solved. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a method for preparing hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials. This method is simple, efficient and environmentally friendly. The resulting composite nanomaterials have excellent microwave absorption properties, overcoming the shortcomings of insufficient microwave absorption properties of single magnetic metal / carbon composite materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials for absorbing microwave radiation, the method comprising the following steps: S1. Dissolve Co(NO3)2·6H2O and CTAB in water to prepare solution A, and dissolve 2-methylimidazole in water to prepare solution B. Then quickly pour solution A into solution B and react for 10~40 min. After centrifugation, washing and drying, cubic ZIF-67 material is obtained. S2. Disperse the ZIF-67 powder obtained in step S1 in ethanol to prepare a suspension. Separately, dissolve four metal hydrated salts, FeCl2·4H2O, NiCl2·6H2O, CuCl2·2H2O, and MnCl2·4H2O, in water to prepare a metal salt solution. Then, quickly add the metal salt solution to the ZIF-67 suspension. It can be observed that the solution changes from purple to dark red rapidly. After stirring the reaction for 10 to 40 minutes, centrifuge, wash, and collect the precipitate. S3. Disperse the precipitate obtained in step S2 into ethanol, add water, and then reflux and stir in a water bath. After stirring, centrifuge, wash and dry to obtain a cubic high-entropy metal hydroxide precursor with a wrinkled surface and a hollow interior. S4. The precursor product obtained in step S3 is calcined to obtain hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial. Then, it is mixed with solid paraffin heated to molten, and after molding, hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material is obtained.

[0007] This invention uses cubic ZIF-67 as a self-sacrificing template and introduces various metal ions such as Fe, Ni, Mn, and Cu into its framework structure through multi-element ion exchange. By leveraging the synchronous etching and metal ion co-precipitation effect induced by ligand competition, a hollow nanocube of high-entropy metal hydroxide with good morphology inheritance is prepared. After subsequent heat treatment, a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material is finally obtained.

[0008] Preferably, in S1, the mass ratio of 2-methylimidazole to Co(NO3)2·6H2O is 14~18:1; the amount ratio of Co(NO3)2·6H2O to CTAB is 1~2 g:10~30 mg; the concentration of CTAB in solution A is 10~30 mg / 20~60 mL; and the concentration of 2-methylimidazole in solution B is 15~20 g / 200~300 mL.

[0009] Preferably, in S2, the mass concentration of the ZIF-67 powder in ethanol is 1.0~1.5 mg / mL; the molar ratio of the FeCl2·4H2O, NiCl2·6H2O, CuCl2·2H2O, and MnCl2·4H2O metal salts is 1:1:0.2~0.6:0.2~0.6; and the concentration of the total hydrated metal salts in the metal hydrated salt solution is 1.0~1.8 mmol / 50 mL.

[0010] Preferably, in S3, the temperature of the water bath reflux stirring is 60~80 ℃, and the time is 20~40 min.

[0011] Preferably, in S4, the calcination is performed by first heating to 200-300℃ at a heating rate of 0.5-1℃ / min for 1-3 hours, and then heating to 450-600℃ at a heating rate of 2-5℃ / min for 1-3 hours, with the calcination atmosphere being a hydrogen / argon mixture.

[0012] More preferably, in the hydrogen / argon gas mixture, the volume ratio of hydrogen to argon is 1:8~10.

[0013] Preferably, in S4, the amount of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial added accounts for 40~50 wt.% of the total mass of the high-entropy alloy / carbon composite nanomaterial and paraffin.

[0014] The second aspect of the present invention also provides a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material prepared by the preparation method described in the first aspect.

[0015] This invention features a simple process, low equipment requirements, and outstanding environmental friendliness. The resulting composite nanomaterial cleverly combines the unique geometric properties of a hollow cubic structure, the synergistic effect between magnetic metals and carbon components, and the lattice distortion and interface polarization effect induced by high-entropy elements. This allows for effective control of electromagnetic parameters, enhanced polarization loss, and optimized impedance matching performance, thereby achieving excellent electromagnetic wave absorption at a relatively thin thickness. This invention provides a novel technical approach for the simplified development and large-scale application of lightweight, high-efficiency microwave absorbing materials.

[0016] The third aspect of this invention also provides the application of the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial described in the first aspect in the preparation of magnetic electromagnetic wave absorbing materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a simple method based on multi-component ion exchange and self-sacrificing templates. Using cubic ZIF-67 as a self-sacrificing template, multiple metal ions such as Fe, Ni, Mn, and Cu are introduced into its framework structure through multi-component ion exchange. By leveraging the synchronous etching and metal ion co-precipitation induced by ligand competition, hollow nanocubes of high-entropy metal hydroxide with well-inherited morphology and a wrinkled surface are prepared. After subsequent heat treatment and composite with paraffin, hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing materials are successfully synthesized.

[0018] The unique hollow structure of this material, combined with the high-entropy effect generated by multiple metallic elements, can significantly improve the microwave absorption performance of magnetic metal / carbon composite nanomaterials, providing a simple new strategy for the development of lightweight and efficient electromagnetic microwave absorbing materials. Furthermore, the method for preparing this composite nanomaterial is simple, requires minimal equipment, and allows for adjustable electromagnetic parameters and microwave absorption performance of the prepared samples, achieving excellent absorption effects even at relatively thin thicknesses. This method uses ZIF-67 as a self-sacrificial template to synthesize a high-entropy metal hydroxide precursor via multi-element ion exchange, followed by high-temperature reduction to prepare multi-metal magnetic alloy / carbon composite nanomaterials. The lattice distortion and interfacial polarization effects induced by the high-entropy elements synergistically enhance the dielectric and magnetic losses of the material, optimizing impedance matching and opening up a completely new avenue for improving the microwave absorption performance of magnetic materials.

[0019] The hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial prepared in this invention can effectively control electromagnetic parameters by adjusting the amount added, thereby obtaining a microwave absorbing material with excellent interfacial polarization loss characteristics. The unique hollow cubic structure of this material, through the synergistic effect of geometric configuration and composition design, simultaneously optimizes impedance matching and integrates multiple loss mechanisms. Its internal hollow structure and porous structure between particles effectively reduce the overall density of the material, facilitating the entry of more electromagnetic waves into the material and their undergoing multiple reflections and absorptions. Furthermore, the unique "high-entropy effect" of the CoFeNiMnCu high-entropy nanoparticles leads to significant lattice distortion and a unique electronic structure. This atomic-scale inhomogeneity induces strong dipole polarization relaxation, contributing significantly to dielectric loss; simultaneously, the numerous heterogeneous interfaces formed between the CoFeNiMnCu high-entropy nanoparticles and the carbon matrix generate strong interfacial polarization. Studies have shown that this hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial exhibits excellent microwave absorption properties: when the addition amount of CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial is 50 wt.% and the thickness is 3.0 mm, its effective absorption bandwidth (absorption intensity >50%) can reach 10.4 GHz (4.6~15.0 GHz). Furthermore, at a thickness of 3.9 mm, the effective absorption bandwidth extends from 3.5 GHz to 13.3 GHz, covering part of the low-frequency S-band, the entire C / X mid-to-high frequency band, and part of the high-frequency Ku-band. Therefore, this material can effectively reduce common electromagnetic interference such as wireless communication, satellite signals, and radar bands, and has practical application value for improving the stability of electronic equipment, ensuring information security, and reducing electromagnetic radiation exposure. It provides a feasible material solution for electromagnetic compatibility and protection issues in modern electronic systems and human living environments. Attached Figure Description

[0020] Figure 1 The image shows the SEM image of the intermediate high-entropy metal hydroxide precursor synthesized in step (3) of Example 1; a and b are SEM images from different perspectives.

[0021] Figure 2 The image shows the XRD pattern of the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial synthesized in Example 1.

[0022] Figure 3 The images show the SEM and EDS spectra of the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial synthesized in Example 1; a is a low-magnification SEM image with a scale bar of 2 μm; b is a medium-magnification SEM image with a scale bar of 500 nm; c is a high-magnification SEM image with a scale bar of 50 nm; and d is an EDS spectrum.

[0023] Figure 4The images show TEM images of the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial synthesized in Example 1; a is a standard TEM image with a scale bar of 200 nm; b is a high-resolution TEM image magnified to 20 nm.

[0024] Figure 5 The elemental distribution diagram is shown for the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial synthesized in Example 1.

[0025] Figure 6 (a) and (b) are the three-dimensional surface plot and two-dimensional curve plot of the microwave absorption performance of the coaxial ring sample prepared in Example 1, respectively. Figure 6 (c) and (d) are the three-dimensional absorption performance surface plot and the two-dimensional absorption performance curve plot of the coaxial ring sample prepared in Example 2, respectively; Figure 6 (e) and (f) are the three-dimensional absorption performance surface diagram and the two-dimensional absorption performance curve diagram of the coaxial ring sample prepared in Example 3, respectively.

[0026] Figure 7 (a) and (b) are respectively the contour plot of the absorption performance of the coaxial ring sample prepared in Example 1 and the curve of the absorption intensity as a function of frequency at a specific thickness; Figure 7 (c) and (d) are respectively the contour plot of the microwave absorption performance of the coaxial ring sample prepared in Example 2 and the curve of the absorption intensity as a function of frequency at a specific thickness; Figure 7 (e) and (f) are respectively the contour plot of the absorption performance of the coaxial ring sample prepared in Example 3 and the curve of the absorption intensity as a function of frequency at a specific thickness. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0029] Example 1: Preparation of hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial for absorbing microwave waves The composite nano-absorbing material is prepared through the following steps: (1) Preparation of cubic ZIF-67 intermediate 1 by liquid phase method: First, 1.16 g of Co(NO3)2·6H2O and 20 mg of CTAB were dissolved in 40 mL of deionized water and stirred until completely dissolved; this solution is denoted as solution A. Separately, 18.16 g of 2-methylimidazole was dissolved in 280 mL of deionized water and magnetically stirred until fully dissolved; this solution is denoted as solution B. Finally, solution A was quickly poured into solution B and stirred continuously until homogeneous. After reacting for 20 min, the mixture was centrifuged, washed (alternating between anhydrous ethanol and deionized water), dried, and the resulting cubic ZIF-67 intermediate 1 of a specific size was collected.

[0030] (2) Preparation of hollow cubic high-entropy metal hydroxide intermediate 2 by multi-component ion exchange and self-sacrificing template: 400 mg of cubic ZIF-67 intermediate 1 prepared by the above reaction was ultrasonically dispersed in 300 mL of anhydrous ethanol and magnetically stirred to form a suspension. Then, 0.6 mmol FeCl2·4H2O, 0.6 mmol NiCl2·6H2O, 0.2 mmol CuCl2·2H2O, and 0.2 mmol MnCl2·4H2O were dissolved in 50 mL of deionized water. The resulting metal salt solution was then rapidly added to the ZIF-67 suspension. The solution rapidly changed from purple to deep red. The reaction was continued with stirring for 20 min. During the reaction, cubic ZIF-67 acted as a self-sacrificing template, initiating simultaneous etching and co-precipitation of metal ions through ligand competition, resulting in high-entropy metal hydroxide hollow nanocubes with good morphological inheritance. After the reaction, the precipitate was collected by centrifugation and washing, and then dispersed in 300 mL of anhydrous ethanol solution. 50 mL of deionized water was added, and the mixture was refluxed and stirred for 25 min at 68 ℃. Reflux provided the necessary energy for the reaction, driving the rearrangement of atoms / ions in the precursor and promoting its transformation from a disordered state to a short-range ordered state, effectively improving the structural stability of the high-entropy metal hydroxide hollow nanocubes. After reflux, centrifugation, washing, and drying yielded a structurally stable hollow cubic high-entropy metal hydroxide intermediate 2 with a wrinkled surface.

[0031] Figure 1 SEM image of the hollow cubic high-entropy metal hydroxide intermediate 2 prepared in this step. Figure 1 As can be seen, a cubic high-entropy metal hydroxide precursor with a wrinkled surface and a hollow interior was successfully prepared by multi-component ion exchange and self-sacrificing template method. The broken cubic structure in the SEM image proves that it has a hollow interior. This result confirms that the multi-component ion exchange and self-sacrificing template process proposed in this invention can effectively synthesize cubic high-entropy metal hydroxides with a wrinkled surface and a hollow interior.

[0032] (3) Intermediate 2 was placed in a tube furnace and heated to 250 °C at a heating rate of 1 °C / min and held for 2 h in a mixed atmosphere of H2 and Ar with a volume ratio of 1:9. Then, it was heated to 500 °C at a heating rate of 2 °C / min and held for 2 h. Subsequently, it was cooled to room temperature in the furnace. The H2 / Ar mixed atmosphere was kept in a flowing state throughout the process, with a flow rate of 20 sccm. Finally, a CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial with a hollow cubic structure was obtained.

[0033] Figure 2 The XRD patterns of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials prepared in this step are shown. The patterns indicate that Co and Ni have similar FCC structures and tend to combine to form a new FCC phase structure. Besides some Fe dissolving in the FCC phase, excess Fe forms a BCC phase structure with Co. No intermetallic compound phases of Mn and Cu were detected in the XRD patterns, indicating that Mn and Cu elements are well dissolved in both the FCC and BCC main phase structures.

[0034] Figure 3 SEM image of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial prepared in this step. Figure 3 As can be seen from a and b, after calcination at 500 ℃, some of the metallic elements on the surface of the hollow cube diffused and connected at high temperature, forming a porous and loose structure. This structure is beneficial for the multiple attenuation and absorption of electromagnetic waves. Furthermore, Figure 3 The magnified SEM image shows that some hollow cubes retain their original cubic morphology well at high temperatures. Due to the high-temperature holding period, protruding metallic nanoparticles diffuse and form on the cube surface. These protruding particles form numerous heterogeneous interfaces with the surrounding carbon matrix. Under the influence of an alternating electromagnetic field, the large amount of space charge accumulated at these interfaces can generate strong interfacial polarization. EDS (Energy Dispersive X-ray Diffusion) spectroscopy... Figure 3 d) It was confirmed that the synthesized high-entropy alloy / carbon composite nanosample contained five metallic elements: Co, Fe, Ni, Cu, and Mn, as well as element C.

[0035] Figure 4 and Figure 5 The images show TEM images and elemental distribution maps of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial prepared in Example 1. The high-resolution TEM image reveals an amorphous carbon layer covering the surface of the metal nanoparticles. The magnetoelectric synergistic matching between the carbon layer and the metal particles is beneficial for improving the electromagnetic absorption performance of the material. The elemental distribution map clearly shows the uniform distribution of the five metal elements, confirming the successful preparation of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial.

[0036] (4) Weigh 72 mg of solid paraffin into a beaker and melt it by heating in a water bath. Then add 48 mg of CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial (the amount added accounts for 40 wt.% of the total mass). After stirring evenly, stop heating in the water bath and wait for it to solidify. Then pour it into a ring mold and press it into a coaxial ring sample with an outer diameter of 7 mm and an inner diameter of 3.04 mm. Finally, test it with a vector network analyzer and obtain the absorption performance value.

[0037] Example 2: The difference from Example 1 is that the mass of paraffin weighed in step (4) of this example is 66 mg, and the mass of CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial added is 54 mg (the amount added accounts for 45 wt.% of the total mass).

[0038] Example 3: The difference from Example 1 is that the mass of paraffin weighed in step (4) of this example is 60 mg, and the mass of CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial added is 60 mg (the amount added accounts for 50 wt.% of the total mass).

[0039] The results of the microwave absorption performance test are as follows: Figure 6 (a) and (b) are respectively the three-dimensional microwave absorption performance surface diagram and the two-dimensional microwave absorption performance curve diagram of the coaxial ring sample provided in Example 1; Figure 6 (c) and (d) are the three-dimensional absorption performance surface diagram and the two-dimensional absorption performance curve diagram of the coaxial ring sample provided in Example 2, respectively; Figure 6 (e) and (f) are the three-dimensional absorption performance surface plot and two-dimensional absorption performance curve plot of the coaxial ring sample provided in Example 3, respectively. The above results show that the prepared hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material has excellent absorption performance. Among them, Example 1 has a strong reflection loss value of -58.6 dB at a thickness of 2.8 mm, Example 2 has a strong reflection loss value of -46.2 dB at a thickness of 2.6 mm, and Example 3 has a strong reflection loss value of -30.2 dB at a thickness of 4.0 mm.

[0040] Figure 7 (a) and (b) are respectively the contour plot of the microwave absorption performance of the coaxial ring sample provided in Example 1 and the curve of the absorption intensity as a function of frequency at a specific thickness; Figure 7 (c) and (d) are respectively the contour plot of the microwave absorption performance of the coaxial ring sample provided in Example 2 and the curve of the absorption intensity as a function of frequency at a specific thickness; Figure 7(e) and (f) are, respectively, the contour plot of the absorption performance of the coaxial ring sample provided in Example 3 and the curve of absorption intensity versus frequency at a specific thickness. The above results confirm that the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial synthesized in this invention has a wide effective absorption bandwidth (absorption intensity >50%). Example 1 has an effective absorption bandwidth of 7.6 GHz at a thickness of 3.8 mm. Example 2 has an effective absorption bandwidth of 9.5 GHz at a thickness of 2.5 mm. Example 3 has an effective absorption bandwidth of 10.4 GHz (4.6~15.0 GHz) at a thickness of 3.0 mm. Furthermore, Example 3 extends the effective absorption bandwidth from 3.5 GHz to 13.3 GHz at a thickness of 3.9 mm. This absorption band completely covers the C-band and X-band, and extends to parts of the S-band and Ku-band, making it widely applicable to typical electromagnetic interference bands such as wireless communication, satellite signals, electronic equipment, and radar systems.

[0041] In summary, the process proposed in this invention can effectively synthesize hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterials with excellent microwave absorption properties, demonstrating promising application prospects.

[0042] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial for absorbing microwave radiation, characterized in that, Includes the following steps: S1. Dissolve Co(NO3)2·6H2O and CTAB in water to prepare solution A, and dissolve 2-methylimidazole in water to prepare solution B. Then quickly pour solution A into solution B and react for 10~40 min. After centrifugation, washing and drying, cubic ZIF-67 material is obtained. S2. Disperse the ZIF-67 powder obtained in step S1 in ethanol to prepare a suspension. Separately, dissolve four metal hydrated salts, FeCl2·4H2O, NiCl2·6H2O, CuCl2·2H2O, and MnCl2·4H2O, in water to prepare a metal salt solution. Then, quickly add the metal salt solution to the ZIF-67 suspension. The solution will be observed to change from purple to dark red rapidly. After stirring the reaction continuously for 10-40 min, centrifuge, wash, and collect the precipitate. S3. Disperse the precipitate obtained in step S2 into ethanol, add water, and then reflux and stir in a water bath. After stirring, centrifuge, wash and dry to obtain a cubic high-entropy metal hydroxide precursor with a wrinkled surface and a hollow interior. S4. The precursor product obtained in step S3 is calcined to obtain hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial. Then, it is mixed with solid paraffin heated to molten, and after molding, hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material is obtained.

2. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S1, the mass ratio of 2-methylimidazole to Co(NO3)2·6H2O is 14~18:

1.

3. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S2, the mass concentration of ZIF-67 powder in ethanol is 1.0~1.5 mg / mL; the molar ratio of the metal salts FeCl2·4H2O, NiCl2·6H2O, CuCl2·2H2O, and MnCl2·4H2O is 1:1:0.2~0.6:0.2~0.

6.

4. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S3, the temperature of the water bath reflux stirring is 60~80 ℃, and the time is 20~40 min.

5. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S4, the calcination is first heated to 200-300℃ at a heating rate of 0.5-1℃ / min and calcined for 1-3 hours, and then heated to 450-600℃ at a heating rate of 2-5℃ / min and calcined for 1-3 hours. The calcination atmosphere is a hydrogen / argon mixture.

6. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 5, characterized in that, In a hydrogen / argon gas mixture, the volume ratio of hydrogen to argon is 1:8~10.

7. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S4, the amount of the CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial added accounts for 40~50 wt.% of the total mass of the high-entropy alloy / carbon composite nanomaterial and paraffin.

8. The preparation method of a hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material according to claim 1, characterized in that, In S1, the ratio of Co(NO3)2·6H2O to CTAB is 1~2 g:10~30 mg.

9. Hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nano-absorbing material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the hollow cubic CoFeNiMnCu high-entropy alloy / carbon composite nanomaterial as described in claim 9 in the preparation of magnetic electromagnetic wave absorbing materials.

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