Preparation method of electromagnetic wave absorbing material and electromagnetic wave absorbing material
By preparing ternary heterostructure electromagnetic wave absorbing materials and utilizing the synergistic optimization of hollow carbon spheres, Ti3C2Tx, and MnO2, the problems of electromagnetic interference and contamination were solved, and a highly efficient electromagnetic wave absorption effect was achieved.
Patent Information
- Application Number
- CN202511444717.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-10
- Publication Date
- 2026-02-17
AI Technical Summary
Existing technologies have failed to effectively address the threats posed by electromagnetic interference and electromagnetic pollution to precision electronic equipment and human health, especially in the context of 5G communication and the Internet of Things, where the performance of electromagnetic wave absorbing materials is insufficient.
By preparing polydopamine-coated silica (SiO2@PDA), coating it with Ti3C2Tx, and then carbonizing and etching it to form hollow carbon spheres @Ti3C2Tx, and then growing MnO2 in situ on it, a ternary heterostructure of electromagnetic wave absorbing material hollow carbon spheres @Ti3C2Tx@MnO2 is formed, which combines the lightweight carrier of hollow carbon spheres, the dielectric polarization of MnO2 and the high conductivity loss characteristics of Ti3C2Tx to achieve synergistic optimization of multiple losses and impedance matching.
It significantly improves the absorption performance of electromagnetic wave absorbing materials, and has the characteristics of being light, thin, wide, and strong. It can effectively absorb electromagnetic waves and reduce electromagnetic interference and pollution.
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Figure CN121548026A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, and in particular to a method for preparing an electromagnetic wave absorbing material and the electromagnetic wave absorbing material itself. Background Technology
[0002] In recent years, the rapid development of 5G communication technology, the Internet of Things, stealth technology, and electronic information technology has led to electromagnetic interference and electromagnetic wave pollution problems. These issues not only seriously affect the normal operation and information security of precision electronic equipment but also pose a potential threat to human health. Therefore, the development of electromagnetic wave absorbing materials is of paramount importance. Summary of the Invention
[0003] In view of the above problems, embodiments of the present invention provide a method for preparing an electromagnetic wave absorbing material and an electromagnetic wave absorbing material, which overcomes or at least partially solves the above problems.
[0004] According to one aspect of the present invention, a method for preparing an electromagnetic wave absorbing material is provided, comprising: preparing polydopamine-coated silica to obtain SiO2@PDA; and coating Ti3C2T onto the SiO2@PDA. x SiO2@Ti3C2T was obtained x / PDA; for the SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x ; in the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x @MnO2.
[0005] In an optional embodiment, the method for preparing polydopamine-coated silica to obtain SiO2@PDA further comprises: mixing a 28 wt% ammonia solution, ethanol, and ultrapure water to obtain a first solution; mixing tetraethyl orthosilicate into the first solution to obtain a second solution; mixing a 50 g / L dopamine hydrochloride solution into the second solution to obtain a first substance; washing the first substance with ultrapure water and then drying it to obtain the SiO2@PDA; wherein the volume ratio of the ammonia solution, the ethanol, the ultrapure water in the first solution, the tetraethyl orthosilicate, and the dopamine hydrochloride solution is 1:24:80:1:8.
[0006] In one alternative approach, the drying conditions for obtaining the SiO2@PDA after washing and drying the first substance with ultrapure water are 60 °C under vacuum for 12 h.
[0007] In an alternative embodiment, the Ti3C2T coating on the SiO2@PDA x SiO2@Ti3C2T was obtained x The / PDA method further includes: using Ti3C2T x The powder and the SiO2@PDA were mixed in deionized water to obtain a first mixture, wherein the Ti3C2T x The mass ratio of powder to SiO2@PDA is 1:1, and 1 mg of Ti3C2T x The powder was treated with 2 mL of deionized water; the first mixture was subjected to sedimentation and centrifugation to obtain a separate; the separate was washed with deionized water and then dried to obtain the SiO2@Ti3C2T. x / PDA.
[0008] In one alternative approach, the first mixture is subjected to sedimentation and centrifugation to obtain the separated product under the following sedimentation conditions: sedimentation at room temperature for 24 hours.
[0009] In an alternative approach, the separated material is washed with deionized water and then dried to obtain the SiO2@Ti3C2T x The drying conditions for the PDA were vacuum drying at 80 ℃ for 24 h.
[0010] In one alternative approach, the SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x The method further includes: taking the SiO2@Ti3C2T x The PDA was heated in an argon atmosphere at 800-900°C for 2 hours and then naturally cooled to room temperature to obtain the first product. The first product was etched with a 10 wt% HF solution for 24 hours to remove the SiO2, yielding the second product. The second product was washed with ethanol and deionized water in a 1:1 volume ratio and then dried to obtain the hollow carbon spheres @Ti3C2T. x .
[0011] In an alternative embodiment, the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x The method using @MnO2 further includes: @Ti3C2T x The first mixture was obtained by dispersing the hollow carbon spheres @Ti3C2T in a KMnO4 solution with a concentration of 20 mmol / L to 40 mmol / L. xCorresponding to 2 mL of the KMnO4 solution; the first mixture was placed in a high-pressure reactor and subjected to a hydrothermal reaction at 140 °C to 160 °C for 2 h, and the reaction product was obtained by filtration; the reaction product was washed with ultrapure water and dried to obtain the hollow carbon spheres @Ti3C2T x @MnO2.
[0012] According to another aspect of the present invention, an electromagnetic wave absorbing material is provided, which is prepared using the above-described method for preparing electromagnetic wave absorbing materials.
[0013] The beneficial effects of this invention include providing a method for preparing an electromagnetic wave absorbing material, comprising: preparing polydopamine-coated silica to obtain SiO2@PDA; and coating the SiO2@PDA with Ti3C2T. x SiO2@Ti3C2T was obtained x / PDA; for the SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x ; in the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x @MnO2. The electromagnetic wave absorbing material obtained by this method is a ternary heterostructure. It utilizes the lightweight carrier and multiple reflection effects of hollow carbon spheres, coupled with the dielectric polarization and morphology control capabilities of MnO2, and further integrates Ti3C2T. x The high conductivity loss and surface modification function enable synergistic optimization of multiple losses and impedance matching, significantly improving the absorption performance of electromagnetic waves. Attached Figure Description
[0014] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.
[0015] Figure 1 This is a schematic flowchart of a method for preparing an electromagnetic wave absorbing material according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of the method for preparing SiO2@PDA provided in an embodiment of the present invention; Figure 3 This is the preparation of SiO2@Ti3C2T provided in the embodiments of the present invention. x A flowchart illustrating the PDA method; Figure 4This invention provides a method for preparing hollow carbon spheres @Ti3C2T. x A flowchart illustrating the method; Figure 5 The hollow carbon spheres@Ti3C2T provided in this embodiment of the invention x A schematic diagram of the process for in-situ growth of MnO2. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0017] This invention provides a method for preparing an electromagnetic wave absorbing material. Please refer to [link / reference]. Figure 1 The method includes the following steps: Step S10: Prepare polydopamine-coated silica to obtain SiO2@PDA.
[0018] PDA, short for Polydopamine, is a biomimetic polymer material with strong adhesion properties. It is formed by the self-polymerization of dopamine under weakly alkaline conditions, uniformly coating the surface of silica microspheres to facilitate subsequent coating with Ti3C2T. x Nanosheets.
[0019] SiO2@PDA refers to a core-shell composite material with SiO2 as the core and PDA as the shell. SiO2@PDA is in powder form.
[0020] In some embodiments, please refer to Figure 2 Methods for preparing SiO2@PDA include: Step S11: Mix a 28 wt% ammonia solution, ethanol, and ultrapure water to obtain the first solution.
[0021] The volume ratio of the ammonia solution, the ethanol, and the ultrapure water in the first solution is 1:24:80.
[0022] A 28 wt% ammonia solution means that the mass fraction of ammonia in the ammonia solution is 28%, and the mass fraction of water is 72%.
[0023] The ethanol used in the embodiments of the present invention can be anhydrous ethanol with a purity of not less than 99.7%.
[0024] Ultrapure water refers to water with a resistivity of 18.2 MΩ·cm, which has extremely low ionization impurity content and is suitable for high-precision chemical experiments and material synthesis processes. Using ultrapure water in the preparation of the first solution effectively avoids interference from ionic impurities in subsequent reactions, ensuring the uniform deposition of the PDA layer on the SiO2 surface.
[0025] The 28 wt% ammonia solution, ethanol, and ultrapure water were mixed for 30 minutes at a stirring speed of 500 rpm to ensure uniform mixing and the formation of a stable alkaline environment.
[0026] Step S12: Tetraethyl orthosilicate is mixed into the first solution to obtain a second solution.
[0027] In this process, tetraethyl orthosilicate serves as the silicon source, undergoing hydrolysis and condensation under alkaline conditions to generate silica microspheres. The volume ratio of the ammonia solution, the ethanol, the ultrapure water in the first solution, and the tetraethyl orthosilicate is 1:24:80:1.
[0028] When tetraethyl orthosilicate is mixed into the first solution, it is stirred continuously for 30 minutes at a stirring speed of 500 rpm to promote the uniform dispersion and controllable hydrolysis of tetraethyl orthosilicate, forming monodisperse silica microspheres.
[0029] Step S13: Mix a 50 g / L dopamine hydrochloride solution into the second solution to obtain the first substance.
[0030] In this process, dopamine hydrochloride undergoes a self-polymerization reaction under a weakly alkaline environment to generate polydopamine, which is then uniformly coated on the surface of silica microspheres.
[0031] The volume ratio of the ammonia solution, the ethanol, the ultrapure water in the first solution, the tetraethyl orthosilicate, and the dopamine hydrochloride solution is 1:24:80:1:8.
[0032] In this process, when a 50 g / L dopamine hydrochloride solution is mixed into the second solution, the mixture is stirred continuously for 36 h at a stirring speed of 500 rpm to ensure that the dopamine is fully polymerized and forms a uniform and dense PDA layer on the surface of the silica microspheres.
[0033] Step S14: Wash the first substance with ultrapure water and then dry it to obtain the SiO2@PDA.
[0034] The washing process can be repeated at least three times by centrifugation-dispersion to thoroughly remove unreacted dopamine hydrochloride and its oligomeric byproducts, ensuring the purity and structural integrity of the final product.
[0035] The drying conditions should be controlled in a vacuum environment at 60 °C for 12 h.
[0036] It is understandable that the methods for preparing SiO2@PDA are not limited to Figure 2 The method shown can also be used to achieve the coating of dopamine on the surface of SiO2 by other chemical polymerization methods. For example, silica microspheres are dispersed in Tris-HCl buffer solution, dopamine hydrochloride is added, and the mixture is stirred at room temperature for 12 hours. Then, the mixture is centrifuged, washed, and dried to obtain a black powder, which is SiO2@PDA.
[0037] Step S20: Coating Ti3C2T onto the SiO2@PDA x SiO2@Ti3C2T was obtained x / PDA.
[0038] Among them, SiO2@Ti3C2T x / PDA is based on SiO2 as the core and Ti3C2T x A core-shell structure with PDA as the coating layer.
[0039] In some embodiments, please refer to Figure 3 Preparation of SiO2@Ti3C2T x / PDA includes: Step S21, Ti3C2T x The powder and the SiO2@PDA were mixed in deionized water to obtain a first mixture, wherein the Ti3C2T x The mass ratio of powder to SiO2@PDA is 1:1, and 1 mg of Ti3C2T x Use 2 mL of deionized water for each powder.
[0040] Among them, Ti3C2T x It is a type of MXene, which possesses a large specific surface area and good hydrophilicity, making it promising for applications in energy storage, catalysis, sensing, and biomedicine. The general formula for MXene is Mn + 1XnTx, where "M" represents an early transition metal, "X" represents carbon and / or nitrogen, and "Tx" represents surface groups. In this embodiment of the invention, MXene is specifically Ti3C2T x .
[0041] Deionized water is pure water from which charged ions (salts) have been removed. Its resistivity ranges from 1 MΩ·cm to 18.2 MΩ·cm.
[0042] Among them, Ti3C2T xWhen the powder and the SiO2@PDA are mixed in deionized water, they need to be stirred at 60 °C for 3 h at a stirring rate of 500 rpm to obtain a homogeneous first mixture. This process realizes Ti3C2T x The effective adsorption and uniform coating of nanosheets on the SiO2@PDA surface lead to the formation of a stable core-shell structure SiO2@Ti3C2T x / PDA.
[0043] Step S22: The first mixture is subjected to sedimentation and centrifugation to obtain the separated product.
[0044] In some embodiments, the sedimentation and centrifugation of the first mixture to obtain the separated product are carried out under the following conditions: sedimentation at room temperature for 24 hours. Specifically, the first mixture is allowed to settle at room temperature for 24 hours, the precipitate at the bottom is removed and placed in a centrifuge tube, and then centrifuged repeatedly with deionized water three times to obtain a solid separated product.
[0045] Step S23: The separated material is washed with deionized water and then dried to obtain SiO2@Ti3C2T x / PDA.
[0046] The separated material was washed with deionized water and then dried to obtain the SiO2@Ti3C2T x The drying conditions for the PDA were vacuum drying at 80 ℃ for 24 h.
[0047] Step S30, for the SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x .
[0048] In some embodiments, please refer to Figure 4 Preparation of hollow carbon spheres@Ti3C2T x The methods include: Step S31, the SiO2@Ti3C2T x The PDA was heated in an argon atmosphere at 800 ℃ to 900 ℃ for 2 h and then naturally cooled to room temperature to obtain the first product.
[0049] In this process, the SiO2@Ti3C2T x The PDA was placed in a tube furnace and heated to 800-900 °C at a rate of 5 °C / min under argon protection, and held for 2 h. It was then allowed to cool naturally to room temperature to obtain the first product. During this pyrolysis process, the PDA was transformed into a carbon layer, while the SiO2 core remained stable, and the Ti3C2T... x The nanosheets are still uniformly distributed on the surface of the carbon layer.
[0050] Step S32: Etch the first product with a 10 wt% HF solution for 24 h to remove the SiO2 and obtain the second product.
[0051] Through selective etching with HF solution, the internal SiO2 is dissolved, forming a hollow structure.
[0052] The specific method for removing SiO2 by etching the first product with a 10 wt% HF solution for 24 h is as follows: the first product is placed in a 10 wt% HF solution and reacted at room temperature for 24 h. After the reaction is completed, centrifugation is performed to obtain a solid second product.
[0053] Step S33: Wash the second product with ethanol and deionized water in a volume ratio of 1:1 and dry it to obtain the hollow carbon spheres @Ti3C2T x .
[0054] The second product can be washed three times.
[0055] The drying process was carried out at 60 °C for 12 h to ensure that the sample was completely dehydrated and to maintain the integrity of the hollow structure.
[0056] Step S40, in the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x @MnO2.
[0057] The hollow carbon spheres @Ti3C2T x @MnO2 is an electromagnetic wave absorbing material.
[0058] In some embodiments, please refer to Figure 5 Step S40, in the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x The methods for @MnO2 include: Step S41, the hollow carbon spheres@Ti3C2T x The first mixture was obtained by dispersing the hollow carbon spheres @Ti3C2T in a KMnO4 solution with a concentration of 20 mmol / L to 40 mmol / L. x This corresponds to 2 mL of the KMnO4 solution.
[0059] The hollow carbon spheres@Ti3C2T xWhen dispersed in KMnO4 solutions with concentrations of 20 mmol / L to 40 mmol / L, the materials are subjected to ultrasonic treatment to ensure thorough dispersion. The ultrasonic treatment time is controlled at 30 min to ensure uniform dispersion of the materials, thus obtaining the first mixture.
[0060] Step S42: The first mixture is placed in a high-pressure reactor and subjected to a hydrothermal reaction at 140 °C to 160 °C for 2 h. The reaction product is then obtained by filtration. During the hydrothermal reaction, KMnO4 decomposes and is reduced to MnO2 under high temperature conditions, which is then deposited in situ on hollow carbon spheres @Ti3C2T x The surface forms a multi-layered core-shell structure of the reaction products.
[0061] The high-pressure reactor has a polytetrafluoroethylene liner, which can withstand highly corrosive environments and ensure the airtightness of the reaction, thus ensuring the smooth progress of the hydrothermal reaction.
[0062] Step S43: The reaction product is washed with ultrapure water and then dried to obtain the hollow carbon spheres @Ti3C2T x @MnO2.
[0063] The washing process can be repeated three times to thoroughly remove residual ionic impurities, ensuring the purity and stability of the final product. The drying process is carried out in a vacuum drying oven at 60 °C for 12 h.
[0064] This invention provides a method for preparing an electromagnetic wave absorbing material, comprising preparing polydopamine-coated silica to obtain SiO2@PDA; and coating the SiO2@PDA with Ti3C2T. x SiO2@Ti3C2T was obtained x / PDA; for the SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x ; in the hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x @MnO2. The electromagnetic wave absorbing material obtained by this method is a ternary heterostructure. It utilizes the lightweight carrier and multiple reflection effects of hollow carbon spheres, coupled with the dielectric polarization and morphology control capabilities of MnO2, and further integrates Ti3C2T. x The high conductivity loss and surface modification function enable synergistic optimization of multiple losses and impedance matching, significantly improving the absorption performance of electromagnetic waves.
[0065] This invention also provides an electromagnetic wave absorbing material, which is prepared using the method described in the above embodiments.
[0066] To facilitate readers' understanding of the inventive concept of the embodiments of the present invention, the technical effects of using the embodiments of the present invention are demonstrated below.
[0067] Example 1 <Preparation of SiO2@PDA> 1 mL of ammonia solution (28 wt%), 24 mL of ethanol, and 80 mL of ultrapure water were mixed and stirred for 30 min at 500 rpm to obtain the first solution. Then, 1 mL of tetraethyl orthosilicate was added to the first solution, and the mixture was stirred continuously for 30 min at 500 rpm to obtain the second solution. Next, 8 mL of a 50 g / L dopamine hydrochloride solution was added dropwise to the second solution, and the mixture was stirred continuously for 36 h at 500 rpm to obtain the first substance. The first substance was washed with ultrapure water and dried under vacuum at 60 °C for 12 h to obtain powdered PDA@SiO2.
[0068] Preparation of SiO2@Ti3C2T x / PDA> Take 5 mg of Ti3C2T x The powder and 5 mg of SiO2@PDA were placed in 10 mL of deionized water and stirred thoroughly at 60 °C for 3 h to obtain a homogeneous first mixture. The mixture was stirred at 500 rpm and allowed to settle at room temperature for 24 h. The precipitate at the bottom was collected and placed in a centrifuge tube. After centrifugation three times with deionized water, the mixture was dried in a vacuum oven at 80 °C for 24 h to obtain SiO2@Ti3C2T. x / PDA.
[0069] Preparation of hollow carbon spheres@Ti3C2T x > SiO2@Ti3C2T x The PDA was placed in a tube furnace and heated to 800 °C at a heating rate of 5 °C / min under an argon atmosphere. After heating for 2 h, it was naturally cooled to room temperature to obtain the first product. The first product was etched with 10 wt% HF solution for 24 h to remove the SiO2 core, yielding the second product. The second product was then washed three times with ethanol and water in a 1:1 volume ratio and vacuum dried at 60 °C for 12 h to obtain hollow carbon spheres. .
[0070] Preparation of hollow carbon spheres@Ti3C2T x @MnO2> 20 mg hollow carbon spheres The mixture was ultrasonically dispersed in 40 mL of potassium permanganate (KMnO4) solution (concentration 20 mmol / L) for 30 min to obtain a first mixture. This first mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 140 °C for 2 h to obtain the reaction product. The reaction product was collected by filtration, washed three times with ultrapure water, and then vacuum dried at 60 °C for 12 h to obtain hollow carbon spheres@Ti3C2T. x @MnO2.
[0071] Example 2 <Preparation of SiO2@PDA> Same as Example 1.
[0072] Preparation of SiO2@Ti3C2T x / PDA> Same as Example 1.
[0073] Preparation of hollow carbon spheres@Ti3C2T x > SiO2@Ti3C2T x The PDA was placed in a tube furnace and heated to 900 °C at a heating rate of 5 °C / min under an argon atmosphere. After heating for 2 h, it was naturally cooled to room temperature to obtain the first product. The first product was etched with 10 wt% HF solution for 24 h to remove the SiO2 core, yielding the second product. The second product was then washed three times with ethanol and water in a 1:1 volume ratio and vacuum dried at 60 °C for 12 h to obtain hollow carbon spheres. .
[0074] Preparation of hollow carbon spheres@Ti3C2T x @MnO2> 20 mg hollow carbon spheres The mixture was ultrasonically dispersed in 40 mL of potassium permanganate (KMnO4) solution (40 mmol / L) for 30 min to obtain a first mixture. This first mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 160 °C for 2 h to obtain the reaction product. The reaction product was collected by filtration, washed three times with ultrapure water, and then vacuum dried at 60 °C for 12 h to obtain hollow carbon spheres@Ti3C2T. x @MnO2.
[0075] Comparative Example 1 <Preparation of SiO2@PDA> Same as Example 1.
[0076] <Preparation of Hollow Carbon Spheres> SiO2@PDA was placed in a tube furnace and heated to 800 ℃ at a heating rate of 5 ℃ / min under an argon atmosphere. After heating for 2 h, it was naturally cooled to room temperature. Then, it was etched with 10 wt% HF solution for 24 h to remove the SiO2 core. It was then washed three times with ethanol and water in a volume ratio of 1:1 and vacuum dried at 60 ℃ for 12 h to obtain hollow carbon spheres.
[0077] <Preparation of hollow carbon spheres@MnO2> 20 mg of hollow carbon spheres were ultrasonically dispersed in 40 mL of potassium permanganate (KMnO4) solution (concentration 20 mmol / L) for 30 min to obtain a mixture. The mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and subjected to a hydrothermal reaction at 140 °C for 2 h to obtain the reaction product. The reaction product was collected by filtration, washed three times with ultrapure water, and then vacuum dried at 60 °C for 12 h to obtain the electromagnetic wave absorbing material, hollow carbon spheres@MnO2.
[0078] The absorption performance of the products prepared in Examples 1, 2, and Comparative Example 1 was tested using an Agilent vector network analyzer, and the testing methods were the same. The test results are shown in Table 1.
[0079] Table 1
[0080] From Table 1, RL min Minimum reflection loss is the core parameter for measuring the ability of electromagnetic wave absorbing materials to absorb electromagnetic waves. The more negative the value (the larger the absolute value), the stronger the material's ability to absorb electromagnetic waves.
[0081] The electromagnetic wave absorbing material (1.50 mm thick) in Example 1 has an RL... min The value is -55.25dB, which is relatively large in absolute terms. Its effective absorption bandwidth is 3.65GHz, which is also relatively wide. This indicates that it has strong electromagnetic wave absorption capability and a wide effective absorption range even with a thinner thickness.
[0082] The electromagnetic wave absorbing material (1.75 mm thick) in Example 2 has an RL... min Its absolute value is -52.56dB, which is relatively large. Its effective absorption bandwidth is 3.22GHz, which is also relatively wide. Its thickness is relatively thin, indicating that it also has strong electromagnetic wave absorption capability and a wide effective absorption range.
[0083] The electromagnetic wave absorbing material (thickness 2.20 mm) in Comparative Example 1 has an RL... minThe value is -27.33dB, which is relatively small in absolute terms. Its effective absorption bandwidth is 1.65GHz, which is narrow and relatively thick, indicating that its ability to absorb electromagnetic waves is weak and its effective absorption range is narrow.
[0084] In summary, the electromagnetic wave absorbing material prepared by the method provided in this application exhibits excellent electromagnetic wave absorption capability even at a relatively small thickness. This may be because the electromagnetic wave absorbing material prepared in this application is a ternary (hollow carbon spheres, Ti3C2T) material. x The heterostructure (MnO2) utilizes the lightweight support and multiple reflection effects of hollow carbon spheres to couple the dielectric polarization and morphology control capabilities of MnO2, and then integrates Ti3C2T x The high conductivity loss and surface modification function. The three factors work together to optimize the impedance matching and attenuation characteristics of the material, breaking through the performance limits of single or binary composite materials (such as Comparative Example 1), and obtaining a new generation of high-performance electromagnetic wave absorbing materials with the characteristics of being lightweight, thin, wide, and strong.
[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing an electromagnetic wave absorbing material, characterized in that, include: Polydopamine-coated silica was prepared to obtain SiO2@PDA; coating Ti3C2T on the SiO2@PDA x , to obtain SiO2@Ti3C2T x / PDA; carboxylated Ti3C2T x carbonization and etching of the SiO2@Ti3C2T x hollow carbon sphere@Ti3C2T The hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x @MnO2.
2. The method for preparing an electromagnetic wave absorbing material according to claim 1, characterized in that, The method for preparing polydopamine-coated silica to obtain SiO2@PDA further includes: A 28 wt% ammonia solution, ethanol, and ultrapure water were mixed to obtain the first solution; Tetraethyl orthosilicate is mixed into the first solution to obtain a second solution; A 50 g / L dopamine hydrochloride solution was mixed into the second solution to obtain the first substance. The first substance was washed with ultrapure water and then dried to obtain the SiO2@PDA; The volume ratio of the ammonia solution, the ethanol, the ultrapure water in the first solution, the tetraethyl orthosilicate, and the dopamine hydrochloride solution is 1:24:80:1:
8.
3. The method for preparing an electromagnetic wave absorbing material according to claim 2, characterized in that, The first substance was washed with ultrapure water and then dried to obtain the SiO2@PDA. The drying conditions were vacuum drying at 60 °C for 12 h.
4. The method for preparing an electromagnetic wave absorbing material according to claim 1, characterized in that, The Ti3C2T coating on the SiO2@PDA x SiO2@Ti3C2T was obtained x The method for / PDA further includes: Ti3C2T x The powder and the SiO2@PDA were mixed in deionized water to obtain a first mixture, wherein the Ti3C2T x The mass ratio of powder to SiO2@PDA is 1:1, and 1 mg of Ti3C2T x Use 2 mL of deionized water for each powder. The first mixture was subjected to sedimentation and centrifugation to obtain the separated product; The separated material was washed with deionized water and then dried to obtain the SiO2@Ti3C2T x / PDA.
5. The method for preparing an electromagnetic wave absorbing material according to claim 4, characterized in that, The first mixture was subjected to sedimentation and centrifugation to obtain the separated product. The sedimentation conditions were settling at room temperature for 24 hours.
6. The method for preparing an electromagnetic wave absorbing material according to claim 4, characterized in that, The separated material was washed with deionized water and then dried to obtain the SiO2@Ti3C2T x The drying conditions for the PDA were vacuum drying at 80 ℃ for 24 h.
7. The method for preparing an electromagnetic wave absorbing material according to claim 1, characterized in that, The SiO2@Ti3C2T x The PDA is carbonized and etched to remove the SiO2, resulting in hollow carbon spheres @Ti3C2T. x The method further includes: The SiO2@Ti3C2T x / PDA was heated in an argon atmosphere at 800 ℃ to 900 ℃ for 2 h and then naturally cooled to room temperature to obtain the first product; The first product was etched with a 10 wt% HF solution for 24 h to remove the SiO2 and obtain the second product. The second product was washed with ethanol and deionized water in a volume ratio of 1:1 and then dried to obtain the hollow carbon spheres @Ti3C2T x .
8. A method for preparing an electromagnetic wave absorbing material according to any one of claims 1-7, characterized in that, The hollow carbon spheres@Ti3C2T x In-situ growth of MnO2 yields hollow carbon spheres in Ti3C2T for electromagnetic wave absorption. x The @MnO2 method further includes: The hollow carbon spheres@Ti3C2T x The first mixture was obtained by dispersing the hollow carbon spheres @Ti3C2T in a KMnO4 solution with a concentration of 20 mmol / L to 40 mmol / L. x Corresponding to 2 mL of the KMnO4 solution; The first mixture was placed in a high-pressure reactor and subjected to a hydrothermal reaction at 140 ℃ to 160 ℃ for 2 h. The reaction product was obtained by filtration. The reaction product was washed with ultrapure water and then dried to obtain the hollow carbon spheres @Ti3C2T x @MnO2.
9. An electromagnetic wave absorbing material, characterized in that, The electromagnetic wave absorbing material is prepared using the method for preparing electromagnetic wave absorbing materials as described in any one of claims 1-8.