A multidimensional nanocomposite absorbing material and its preparation method and application

Abstract

The present invention belongs to the field of absorbing materials, specifically to a multidimensional nanocomposite absorbing material, its preparation method, and application. The preparation method comprises: mixing nickel salt hydrate, cobalt salt hydrate, and copper salt hydrate in a designed ratio and dissolving them in water to form liquid A; preparing alkaline liquid B; then adding a MXene dispersion to a container, adding liquid A and liquid B dropwise to maintain an alkaline environment in the mixed liquid; then adding a carbon nanotube composite conductive agent and Fe3O4 nanoparticles, reacting at room temperature, then heating, and finally centrifuging and washing the product. The present invention innovatively develops a MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbing material with excellent absorbing performance, prepared by a simple double-drop co-precipitation method and hydrothermal method, and greatly reduces raw material costs while simplifying the preparation process.

Description

Technical Field

[0001] The present invention belongs to the field of wave-absorbing materials, and in particular relates to a multi-dimensional nano-composite wave-absorbing material and a preparation method and application thereof. Background Art

[0002] With the booming electronics industry and the increasing adoption of 5G networks, electromagnetic waves (EMW) have become commonplace in our daily lives. While these ubiquitous electromagnetic waves bring convenience, they also pose a significant threat of electromagnetic pollution, affecting the operation of electronic devices and negatively impacting human health. Against this backdrop, absorbing materials have emerged. Absorbing materials have a wide range of applications in both civilian and military fields, particularly in stealth coatings and satellite radar. To achieve efficient electromagnetic wave absorbing materials with strong absorption capacity, a wide absorption bandwidth, and the thinnest possible matching thickness, designing their structure and composition is essential.

[0003] Hydrotalcite is a two-dimensional anionic material composed of positively charged layers and interlayer anions. Thanks to its tunable interlayer spacing and anionic structure, combined with its positively charged host layers and two-dimensional structure, hydrotalcite has been widely used in many fields, such as catalysis, energy storage, and adsorption. Despite its versatility and potential, reports on its use as an EMW absorber are limited. Meanwhile, traditional single metal oxides, such as Fe2O3, Fe3O4, Co3O4, TiO2, and NiO, fall short of the requirements for efficient EMW absorbers due to their inherent limitations. They are often limited by low electrical conductivity, poor impedance matching, and high density. Consequently, much research has focused on combining metal oxides with other dielectric materials (carbon materials and polymers) via hydrothermal, in situ growth, and sol-gel methods to create efficient hybrid materials. Currently, many carbon materials, such as graphene, carbon nanotubes, and MXene, have been used to tune the relative complex permittivity and permeability of composites, but their complex preparation methods and high cost hinder their further application in microwave absorption.

[0004] Traditional hydrotalcite-based absorbing materials often require the addition of large amounts of materials with good conductive properties, such as MXene, graphene, and silicon carbide nanowires, to increase the dielectric loss capacity of the absorbing materials. The complex preparation methods and high prices of these materials hinder their further large-scale application in the field of absorbing materials. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention innovatively developed a MXene-NiCoCu-Fe-CNT type nanocomposite hydrotalcite absorbing material with good absorbing performance prepared by a simple double-drop co-precipitation method and hydrothermal method, and greatly reduced the raw material cost while simplifying the preparation process.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a preparation method of a multidimensional nanocomposite absorbing material. The preparation method comprises: mixing nickel salt hydrate, cobalt salt hydrate and copper salt hydrate according to a designed ratio and dissolving them in water to form liquid A; preparing alkaline liquid B; then adding a MXene dispersion into a container, adding liquid A and liquid B dropwise to maintain an alkaline environment for the mixed liquid; then adding a carbon nanotube composite conductive agent and Fe3O4 nanoparticles, reacting at room temperature and then heating, and finally centrifuging and washing the product.

[0008] In the above scheme, the double drop coprecipitation method is a kind of low saturation coprecipitation method. According to a certain ratio, the metal salt solution is made into a mixed salt solution (SolS) of a certain concentration, and NaOH and Na2CO3 are made into a mixed alkali solution (SolB) according to a certain ratio. SolS and SolB are dripped into a large beaker at a certain dripping speed at the same time, and the pH of the reaction system is maintained at a constant value and stirred vigorously. After the titration is completed, stirring and aging are continued, and finally the product is obtained by filtering, washing, and drying. The hydrothermal synthesis method is to first slowly drop SolS and SolB together and quickly mix them, and then the resulting slurry is immediately transferred to a certain temperature and aged for a long time, and finally filtered, washed, dried, and ground to obtain the product. This method is characterized by isolating the nucleation and crystallization processes of hydrotalcite and promoting the crystallization process by increasing the aging temperature and pressure. Since no other impurities are introduced into the hydrothermal synthesis method, the prepared material has excellent properties such as fine powder (nanoscale), high purity, good dispersibility, uniform particles, complete grain development, and controllable shape. In addition, the hydrothermal method can avoid shortcomings such as stress-induced defects and phase reactions. More importantly, the hydrothermal method can control the morphology, size, viscosity distribution, etc. of the product by adjusting the reaction conditions.

[0009] As a further optimized solution of the present invention, the molar ratio of the nickel salt hydrate, the cobalt salt hydrate and the copper salt hydrate is (4.5-5.5):(1.5-2.5):1.

[0010] As a further optimization solution of the present invention, the nickel salt hydrate is selected from NiCl2·6H2O, Ni(NO3)2·6H2O, or NiSO4·6H2O; the cobalt salt hydrate is selected from CoCl2·6H2O, Co(NO3)2·6H2O, or CoSO4·6H2O; and the copper salt hydrate is selected from CuCl2·2H2O, Cu(NO3)2·3H2O, or CuSO4·5H2O. Among them, chlorides have lower cost and better safety.

[0011] As a further optimization solution of the present invention, the alkaline solution B is prepared by mixing a NaOH solution and a Na2CO3 solution. The use of a mixed solution of NaOH and Na2CO3 can more conveniently adjust the pH and control the stable progress of the reaction.

[0012] As a further optimization solution of the present invention, the pH value of the mixed solution is maintained at 9.5-10.5. Maintaining the pH at around 10 can make it easier for metal salt ions to react with hydroxide to form a hydrotalcite structure.

[0013] As a further optimization of the present invention, the mass ratio of MXene, carbon nanotube composite conductive agent, and Fe3O4 nanoparticles is (3.75-10):(100-200):(231-462). The addition of carbon nanotube composite conductive agent and ferrosoferric oxide significantly reduces the amount of MXene used, reducing costs.

[0014] As a further optimized solution of the present invention, the reaction time at room temperature is 0.5-1.5 hours, and the heating treatment is carried out in a water bath at 70° C. for 3.5-4.5 hours.

[0015] The present invention also provides a multi-dimensional nano-composite wave-absorbing material, which is prepared by the preparation method.

[0016] The present invention also provides an application of the multidimensional nanocomposite absorbing material, wherein the multidimensional nanocomposite absorbing material is used for stealth coatings, satellite radars or electromagnetic shielding of electronic equipment.

[0017] As a further optimization solution of the present invention, the thickness of the multi-dimensional nano-composite absorbing material is 2-6 mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention incorporates carbon nanotubes into the system of hydrotalcite-based absorbing materials as a tool for regulating the dielectric loss and conductivity of the material. Furthermore, among various types of carbon nanotubes of different specifications, the present invention innovatively selects a carbon nanotube composite conductive agent with a lower cost, whose price-to-weight ratio is only one percent of that of ordinary carbon nanotubes, while maintaining good dielectric loss capability. A reflection loss of -47dB is achieved at 6.2GHz, and an effective absorption bandwidth of 4.72GHz is achieved at a thickness of 2.4mm. At the same time, by regulating the different thicknesses of the material (2-6mm), broad-spectrum absorption covering the Ku band (12-18GHz), X band (8-12GHz), and C band (4-8GHz) can be successfully achieved. This means that the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbing material synthesized based on this method has great development and large-scale production potential in the field of absorbing waves.

[0020] In summary, based on the traditional MXene-type hydrotalcite absorbing material, the present invention introduces a low-cost carbon nanotube composite conductive agent to replace the expensive MXene to regulate the dielectric loss capacity of the material, greatly reducing the amount of MXene used. At the same time, Fe3O4 nanoparticles are added to regulate the magnetic loss capacity of the material, maintaining good absorbing performance while greatly reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a transmission electron microscope (TEM) image of the MXene-NiCoCu-Fe-CNT type nanocomposite hydrotalcite absorbing material prepared in Example 1 of the present invention.

[0022] Figure 2 Transmission electron microscopy (TEM) image of the Fe3O4 nanoparticles selected for the present invention.

[0023] Figure 3 3D graph of the reflection loss (RL) of MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbers with different thicknesses in the range of 1-18 GHz.

[0024] Figure 4 This is a two-dimensional graph showing the reflection loss (RL) of MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber with a thickness of 2.4 mm as a function of frequency.

[0025] Figure 5 This is a two-dimensional graph showing the reflection loss (RL) of MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbers at different thicknesses as a function of frequency.

[0026] Figure 6 This is a two-dimensional graph of the composite dielectric constant of MXene-NiCoCu-Fe-CNT type nanocomposite hydrotalcite absorbing material changing with frequency in the range of 1-18 GHz.

[0027] Figure 7 This is a two-dimensional graph showing the variation of the composite magnetic permeability of MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbing material with frequency in the range of 1-18 GHz.

[0028] Figure 8 This is a two-dimensional graph showing the variation of the tangent angle of dielectric loss and magnetic loss of MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber with frequency in the range of 1-18 GHz. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, these examples are not to be construed as limiting the present invention and are merely examples.

[0030] The carbon nanotube composite conductive agent used in the embodiment of the present invention was purchased directly from Aladdin Company for lithium-ion battery. The price is lower than that of MXene and ordinary carbon nanotubes, which is 164 yuan / 25g. x )MXene few-layer dispersion.

[0031] Example 1:

[0032] A mixture of 713.07 mg, 285.52 mg, and 102.3 mg of the components n(NiCl2·6H2O):n(CoCl2·6H2O):n(CuCl2·2H2O) (5:2:1) was dissolved in 15 ml of water to form Solution A. The molar concentration of each component, V(NaOH):V(Na2CO3), was 0.5 mol / L at 3.2:1. These components were mixed and used as Solution B. To a 100 ml round-bottom flask, 1 ml of MXene dispersion (5 mg / ml) was added dropwise. Solution A and Solution B were then maintained at a pH of 10 until the addition of Solution A was complete. Then, 100 mg of a carbon nanotube composite conductive agent and 1 mmol of Fe3O4 nanoparticles were added. After reacting at room temperature for 1 hour, the mixture was transferred to a water bath at 70°C and continued to react for 4 hours. The product was centrifuged at 10,000 rpm for 10 minutes and washed three times with anhydrous ethanol and three times with ultrapure water.

[0033] Example 2

[0034] A mixture of 713.07 mg of NiCl₂·6H₂O, 285.52 mg of CoCl₂·6H₂O, and 102.3 mg of CuCl₂·2H₂O (n(NiCl₂·6H₂O)):n(CoCl₂·6H₂O) in a ratio of 5:2:1 was dissolved in 15 ml of water to form Solution A. The mixture was then mixed to form Solution B, with a molar concentration of 0.5 mol / L for each solution (V(NaOH):V(Na₂CO₃)) of 3.2:1. 2 ml of 5 mg / ml MXene dispersion was added to a 100 ml round-bottom flask. Solution A and Solution B were then added dropwise, maintaining the pH of the mixture at 10 until the addition of Solution A was complete. 150 mg of a carbon nanotube composite conductive agent and 1 mmol of Fe₃O₄ nanoparticles were then added. After reacting at room temperature for 1 hour, the mixture was transferred to a water bath at 70°C and continued to react for 4 hours. The product was then centrifuged at 9000 rpm for 10 minutes and washed once with anhydrous ethanol and twice with ultrapure water.

[0035] Example 3

[0036] Dissolve 641.76 mg, 214.14 mg, and 102.3 mg of a mixture of n(NiCl2·6H2O):n(CoCl2·6H2O):n(CuCl2·2H2O) (4.5:1.5:1) in 15 ml of water to form Solution A. Mix 1 ml of MXene dispersion (5 mg / ml) in a solution of V(NaOH):V(Na2CO3) at 3.2:1, with a molar concentration of 0.5 mol / L. Add Solution A and Solution B dropwise to a 100 ml round-bottom flask, maintaining the pH of the mixture at 10.5 until all Solution A additions are complete. Then, add 200 mg of a carbon nanotube composite conductive agent and 1.5 mmol of Fe3O4 nanoparticles. After reacting at room temperature for 0.5 h, the mixture was transferred to a water bath at 70°C and continued to react for 3.5 h. The product was centrifuged at 8000 rpm for 10 min and washed twice with anhydrous ethanol and once with ultrapure water.

[0037] Example 4

[0038] Dissolve 784.38 mg, 356.9 mg, and 102.3 mg of a mixture of n(NiCl2·6H2O):n(CoCl2·6H2O):n(CuCl2·2H2O) (5.5:2.5:1) in 15 ml of water to form Solution A. Mix 0.75 ml of MXene dispersion (5 mg / ml) in a solution of V(NaOH):V(Na2CO3) at 3.2:1, with a molar concentration of 0.6 mol / L. Add Solution A and Solution B dropwise to a 100 ml round-bottom flask, maintaining the pH of the mixture at 9.5 until all Solution A additions are complete. Then, add 100 mg of a carbon nanotube composite conductive agent and 2 mmol of Fe3O4 nanoparticles. After reacting at room temperature for 1.5 h, the mixture was transferred to a water bath at 70° C. and continued to react for 4.5 h. The product was centrifuged at 9000 rpm for 10 min, and washed twice with anhydrous ethanol and three times with ultrapure water.

[0039] The present invention takes the product prepared in Example 1 as an example to illustrate its synthesis results and performance characterization:

[0040] Figure 1A transmission electron microscopy (TEM) image of the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber prepared in Example 1 is shown. The image shows the NiCoCu hydrotalcite in the upper left corner exhibiting a characteristic two-dimensional layered structure with numerous wrinkles, the middle portion containing interconnected and irregularly shaped Fe₃O₄ nanoparticles, and the lower right corner containing extended, branched carbon nanotubes. These structures combine to create a large surface area and additional void space, while maintaining good magnetic and dielectric loss, which facilitates the overall electromagnetic wave absorption of the material.

[0041] Figure 2 The transmission electron microscope (TEM) image of Fe3O4 nanoparticles used in the material preparation is shown. Figure 1 The structural composition of the middle portion of the sample has the same morphology and size, indicating that the sample is composed of Fe₃O₄ nanoparticles. The irregularly shaped Fe₃O₄ nanoparticles combined with each other provide the material with an irregular surface and good magnetic properties, enhancing the material's magnetic loss capacity and microwave absorption performance. The overall microwave absorption efficiency of the material can be easily controlled by controlling the dosage.

[0042] Figure 3 A three-dimensional graph showing the reflection loss (RL) of MXene-NiCoCu-Fe-CNT type nanocomposite hydrotalcite absorbers with different thicknesses in the range of 1-18 GHz. Figure 4 The maximum effective absorption bandwidth reached at 2.4mm is 4.72GHz, ranging from 12.97GHz to 17.69GHz. As can be seen from the figure, the minimum reflection loss of NiCoCu absorber is -47.22dB, corresponding to a frequency of 6.29GHz and a thickness of 5.2mm. The maximum effective absorption bandwidth (EAB) is 4.72GHz with a thickness of 2.4mm, which almost covers the entire Ku band. At the same time, Figure 5 The effective absorption frequency range of the material at different thicknesses is shown. As can be seen from the figure, by adjusting the material thickness (2-6 mm), broad-spectrum absorption can be successfully achieved, covering the Ku-band (12-18 GHz), X-band (8-12 GHz), and C-band (4-8 GHz). This demonstrates that the synthesized MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber exhibits excellent absorption performance across the entire frequency range.

[0043] Figure 6The composite dielectric constant, including both real and imaginary parts, of the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber in the 1-18 GHz range is shown. As can be seen, both the real (e') and imaginary (e") parts of the composite dielectric constant decrease with increasing frequency. Within the 1-8 GHz range, the real part decreases from 8.9 to approximately 6.1, and the imaginary part decreases from 3.5 to approximately 2.1. Within the 5-18 GHz range, the real part remains between 5 and 6, and the imaginary part remains between 1 and 2. This demonstrates that the synthesized MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber exhibits excellent dielectric storage and loss capabilities across the entire frequency range.

[0044] Figure 7 The composite magnetic permeability, including both real and imaginary parts, of the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber in the 1-18 GHz range is shown. As the frequency increases, the real part (u') of the composite magnetic permeability remains between 0.8 and 1.0; the imaginary part (u") decreases from 0.78 to approximately 0.2 in the 1-5 GHz range and remains between -0.1 and 0.2 in the 5-18 GHz range. This demonstrates that the synthesized MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber exhibits a certain degree of magnetic storage and loss capacity across the entire frequency range.

[0045] Figure 8 The tangent angles of the dielectric and magnetic losses of the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber are shown in the 1-18 GHz range, representing the material's ability to dissipate electromagnetic waves. As can be seen from the figure, within the 1-3 GHz range, the material's magnetic loss capacity is greater than its dielectric loss capacity, with the magnetic loss peak at 0.78 at 1.2 GHz, then decreasing to 0.4. Within the 3-18 GHz range, the magnetic loss capacity is less than the dielectric loss capacity and decreases with increasing frequency, ultimately fluctuating around 0.1. The dielectric loss capacity, on the other hand, is more stable, primarily remaining around 0.3. This demonstrates that the synthesized MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber exhibits a certain degree of magnetic storage and loss capacity across the entire frequency range, with dielectric loss predominating and the loss capacity being more stable.

[0046] Comparative Example

[0047] The performance of the MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorbing material prepared in Example 1 of the present invention was compared with various absorbing materials reported in relevant literature, including loading capacity, minimum reflection loss, maximum effective absorption bandwidth, and thickness. The specific comparison results are shown in Table 1 below.

[0048] Table 1

[0049]

[0050]

[0051] Among them, MXene-SiCnw is from the literature: Wang, Y.; Dou, Q.; Jiang, W.; Su, K.; You, J.; Yin, S.; Wang, T.; Yang, J.; Li, Q. Ti3C2TX MXene Beaded SiC Nanowires for Efficient Microwave Absorption. ACS Appl. Nano Mater. 2022, 5, 9209 - 9222; MXene / ZnIn2S4 is from the literature: Li, X.; Wang, G.; Li, Q.; Wang, Y.; Lu, X. Dual optimized Ti3C2Tx MXene@ZnIn2S4 Heterostructure Based on Interface and Vacancy Engineering for Improving Electromagnetic Absorption. Chem. Eng. J. J. 2023, 453, No. 139488; NiCo2O4 NSs-MXene is from the literature: Zeng, X.; Zhao, C.; Yin, Y.; Nie, T.; Xie, N.; Yu, R.; Stucky, G. D. Construction of NiCo2O4 Nanosheets-Covered Ti3C2Tx MXene Heterostructure for Remarkable Electromagnetic Microwave Absorption. Carbon 2022, 193, 26 - 34; MXene@GO is from the literature: Li, Y.; Meng, F.; Mei, Y.; Wang, H.; Guo, Y.; Wang, Y.; Peng, F.; Huang, F.; Zhou, Z. Electrospun Generation of Ti3C2Tx MXene@graphene Oxide Hybrid Aerogel Microspheres for Tunable High-Performance Microwave Absorption. Chem. Eng. J. 2020, 391, No.123512; MXene / CoNi / N-CNT from the literature: Designed 3D heterostructure with 0D / 1D / 2D hierarchy for low-frequency microwave absorption in the S-band; CNT-MXene-F-rGO from the literature: Fabrication of multi-dimensional heterostructure towards highly efficient microwave absorbing performance and flame retardancy.; CoFeAl-LDH / G from the literature: hybrids Laminated graphene oxide-supported high-efficiency microwave absorber fabricated by an in situ growth approach; NiCo-LDH / MXene from the literature: Synthesis of NiCo-LDH / MXene hybrids with abundant heterojunction surfaces as a lightweight electromagnetic wave absorber; CoNiM@C (M = Cu, Fe, Mn) from the literature: MOFs-Derived Strategy and Ternary Alloys Regulation in Flower-Like Magnetic-Carbon Microspheres with Broadband Electromagnetic Wave Absorption.

[0052] As shown in Table 1, the synthesized MXene-NiCoCu-Fe-CNT nanocomposite hydrotalcite absorber exhibits some advantages over other absorbers in terms of loading capacity, minimum reflection loss, maximum effective absorption bandwidth, and thickness. Furthermore, conventional hydrotalcite absorbers often require the addition of large quantities of highly conductive materials such as MXene, graphene, and silicon carbide nanowires to increase the absorber's dielectric loss capacity. The complex preparation methods and high cost of these materials hinder their widespread application in the absorber field. The present invention utilizes a more cost-effective carbon nanotube composite conductive agent, with a weight-to-weight ratio of only one percent that of conventional carbon nanotubes, to replace MXene in regulating the material's dielectric loss. This reduces the MXene content from 75%wt in NiCo-LDH / MXene literature to 0.5%wt, significantly reducing the MXene dosage while maintaining the material's excellent dielectric loss capacity.

[0053] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a multidimensional nanocomposite absorbing material, characterized in that: The preparation method includes: mixing nickel salt hydrate, cobalt salt hydrate and copper salt hydrate according to a designed ratio and dissolving them in water to form liquid A; preparing alkaline liquid B; then adding MXene dispersion into a container, adding liquid A and liquid B dropwise to maintain an alkaline environment in the mixed liquid; then adding carbon nanotube composite conductive agent and Fe3O4 nanoparticles, reacting at room temperature and then heating, and finally centrifuging and washing the product.

2. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1, wherein: The molar ratio of the nickel salt hydrate, the cobalt salt hydrate and the copper salt hydrate is (4.5-5.5):(1.5-2.5):

1.

3. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1 or 2, characterized in that: The nickel salt hydrate is selected from NiCl2·6H2O, Ni(NO3)2·6H2O or NiSO4·6H2O, the cobalt salt hydrate is selected from CoCl2·6H2O, Co(NO3)2·6H2O or CoSO4·6H2O, and the copper salt hydrate is selected from CuCl2·2H2O, Cu(NO3)2·3H2O or CuSO4·5H2O.

4. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1, wherein: The alkaline solution B is prepared by mixing NaOH solution and Na2CO3 solution.

5. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1 or 4, characterized in that: The pH value of the mixed solution is maintained at 9.5-10.

5.

6. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1, wherein: The mass ratio of the MXene, carbon nanotube composite conductive agent and Fe3O4 nanoparticles is (3.75-10):(100-200):(231-462).

7. The method for preparing a multidimensional nanocomposite absorbing material according to claim 1, wherein: The reaction time at room temperature is 0.5-1.5 hours, and the heating treatment is carried out in a water bath at 70° C. for 3.5-4.5 hours.

8. A multidimensional nanocomposite absorbing material, characterized in that: The multidimensional nanocomposite absorbing material is prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the multidimensional nanocomposite absorbing material according to claim 8, characterized in that: The multi-dimensional nano composite wave absorbing material is used for stealth coatings, satellite radars or electromagnetic shielding of electronic equipment.

10. The use according to claim 9, characterized in that The thickness of the multi-dimensional nano-composite wave absorbing material is 2-6 mm.

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