A multi-element doped binary composite carbon material and its preparation method and application

Abstract

The present invention discloses a multi-element-doped binary composite carbon material, its preparation method, and application, belonging to the technical field of electromagnetic wave absorbing material preparation. The preparation method of the binary composite carbon material comprises the following steps: 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone and N-hydroxymethyl acrylamide are alkylated to prepare a sulfonic acid functional monomer; tetrabromobisphenol A, methacrylic anhydride, and p-toluenesulfonic acid are esterified to prepare a bromine functional monomer; the sulfonic acid functional monomer and the bromine functional monomer are subjected to free radical polymerization to prepare a binary polymer; and finally, the binary polymer is carbonized. The multi-element-doped binary composite carbon material prepared by the preparation method of the present invention has a minimum reflection loss of 55.25dB in the 2-18 GHz frequency band, providing a new approach to solving the bottleneck problems of existing absorbing materials, such as a single loss mechanism, weak attenuation capability, and complex preparation process.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave absorbing material preparation, and in particular relates to a multi-element doped binary composite carbon material and a preparation method and application thereof. Background Art

[0002] The use of electromagnetic waves (EMW) has opened the door to the information revolution, but electromagnetic radiation can interfere with nearby circuits or delicate electronic devices and may also cause health problems such as cancer, headaches, depression, and fatigue. Most currently developed EMW absorbing materials still have serious flaws. Therefore, developing new EMW absorbing materials that combine multiple synergistic loss mechanisms, strong reflection attenuation performance, and scalable fabrication processes has become a key approach to breaking through the bottlenecks in electromagnetic pollution prevention and control technologies.

[0003] Based on the electromagnetic loss mechanism, microwave absorbing materials can be divided into magnetic materials and dielectric materials. Traditional metal-based magnetic loss-type materials include ferrites and metal powders. Dielectric loss-type materials are mainly carbon-based materials.

[0004] All of the aforementioned electromagnetic wave absorbing materials have limitations. Ferrites or magnetic metals, among others, are difficult to apply on a large scale due to their high cost, bulk, and corrosion susceptibility. Carbon absorbers, including carbon black, conductive graphite, carbon nanotubes, carbon fibers, expanded graphite, and graphite oxide, hold the greatest potential for application due to their diverse structures, chemical stability, and tunable dielectric properties. However, they suffer from a single loss mechanism and inherently narrow absorption band, making them difficult to meet the diverse performance requirements across multiple frequency bands.

[0005] Therefore, how to achieve the coordination of multiple loss mechanisms, optimization of impedance matching and simple preparation remains a key issue that needs to be urgently addressed in the field of electromagnetic wave absorption. Summary of the Invention

[0006] To address these technical issues, the present invention proposes a multi-element-doped binary composite carbon material, its preparation method, and its application. Through molecular structure design and monomer functionalization, heterogeneous elements such as S / N / Br are introduced. A carbon-based absorber with a unique microstructure is constructed by combining free radical polymerization with high-temperature carbonization.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention:

[0009] A method for preparing a multi-element doped binary composite carbon material comprises the following steps:

[0010] Sulfonic acid functional monomer ABHMA was prepared by alkylation reaction of 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone and N-hydroxymethyl acrylamide;

[0011] The bromine functional monomer PDM is prepared by esterification of tetrabromobisphenol A, methacrylic anhydride and p-toluenesulfonic acid.

[0012] The sulfonic acid functional monomer and the bromine functional monomer are reacted by free radical polymerization to prepare a binary polymer P-ABHMA@PDM;

[0013] The binary polymer is sequentially carbonized, cooled and ground to prepare a multi-element doped binary composite carbon material CP-ABHMA@PDM.

[0014] Beneficial Effects: This invention prepares ABHMA (sulfonic acid functional monomer) containing S / N elements and PDM (bromine functional monomer) containing Br elements through Friedel-Crafts alkylation and esterification, respectively. Based on the monomer ratio, free radical polymerization is then used to synthesize binary polymers in various shapes (spherical, French fry, and popcorn), achieving multi-element doping and microstructure design. High-temperature carbonization is then performed to form a multi-element-doped carbon-based composite material. Vector network analyzer testing shows that the multi-element-doped binary composite carbon material prepared in this invention achieves a minimum reflection loss of -55.25 dB in the 2-18 GHz frequency band. This provides a new approach to addressing the bottlenecks of existing absorbers, such as the single loss mechanism, weak attenuation capability, and complex preparation processes.

[0015] Optionally, the molar ratio of the 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone to N-hydroxymethyl acrylamide is 1:1.0-1.5.

[0016] Optionally, the alkylation reaction is carried out at a temperature of 35-40° C. for 3 days.

[0017] Optionally, the molar ratio of the p-toluenesulfonic acid, tetrabromobisphenol A and methacrylic anhydride is (0.005-0.01):1:(2.0-2.5).

[0018] Optionally, the esterification reaction is carried out at a temperature of 45-50° C. for 1 day.

[0019] Optionally, the molar ratio of the sulfonic acid functional monomer to the bromine functional monomer is: (1:3)-(3:1).

[0020] Furthermore, the molar ratio of the sulfonic acid functional monomer to the bromine functional monomer is 1:3, 3:1 or 1:1.

[0021] Furthermore, the molar ratio of the sulfonic acid functional monomer to the bromine functional monomer is 1:1.

[0022] Optionally, the free radical polymerization reaction is carried out at a temperature of 70 to 75° C. and a stirring speed of 300 rpm for 3.0 to 3.5 hours.

[0023] Optionally, the carbonization is performed in stages, specifically:

[0024] First, the temperature is raised to 200 °C at a rate of 1-2 °C / min and maintained at this temperature for 0.8-1.2 h for pre-oxidation;

[0025] Then, the temperature is raised to 700 °C at a rate of 1 to 2 °C / min and maintained at this temperature in an inert atmosphere for 1.5 to 2.5 h to complete carbonization.

[0026] Furthermore, the inert atmosphere is high-purity nitrogen or argon, and the flow rate is 200-300 mL / min.

[0027] The second technical solution of the present invention:

[0028] A multi-element doped binary composite carbon material is prepared by the above preparation method.

[0029] The third technical solution of the present invention:

[0030] Application of the above-mentioned multi-element doped binary composite carbon material in the field of electromagnetic wave absorption.

[0031] Compared with the prior art, the present invention has the following advantages and technical effects:

[0032] 1. Realize multi-element synergistic doping to enhance dielectric loss capability

[0033] By synthesizing ABHMA monomers containing S and N and PDM monomers containing bromine (Br), this method achieves co-doping of multiple heterogeneous elements, such as S, N, and Br, during the polymerization process, effectively regulating the electronic structure and conductive properties of the material. The introduction of these heterogeneous atoms not only enriches the functional groups on the material's surface but also improves its dielectric loss capability over a wide frequency range.

[0034] 2. Constructing a special microstructure to promote the synergistic effect of multiple loss mechanisms

[0035] By adjusting the molar ratio of ABHMA to PDM (3:1, 1:1, 1:3), spherical, French fry, and popcorn-shaped binary copolymer precursors were successfully prepared. After carbonization, carbon materials with unique microstructures were formed. This structural feature brings the following advantages:

[0036] The unique structural design significantly increases its specific surface area, which not only effectively improves the scattering and reflection of electromagnetic waves inside the material; at the same time, it contributes to the occurrence of interface polarization, forming a large number of electric dipole moments under the action of an external electromagnetic field, thereby further improving the electromagnetic wave absorption performance of the material.

[0037] 3. Optimize impedance matching characteristics and broaden the effective absorption band

[0038] Traditional carbon-based absorbing materials often have excessive conductivity, resulting in significant surface reflection of electromagnetic waves, making it difficult for them to penetrate the material for effective absorption. However, the present invention, through a combination of elemental doping and structural manipulation, can promote multiple reflections and scattering of electromagnetic waves, helping to optimize impedance matching. Furthermore, testing has shown that the composite carbon material prepared by the present invention exhibits broadband absorption characteristics within the 2-18 GHz frequency band, with a minimum reflection loss of -55.25 dB. Its effective absorption bandwidth covers multiple GHz, meeting the requirements for multi-band, broadband absorption in modern communication systems.

[0039] 4. The process is green and efficient, with potential for large-scale production

[0040] The preparation method employed in this invention involves Friedel-Crafts alkylation, esterification, free radical polymerization, and carbonization, all of which are mature, controllable organic synthesis and material processing technologies. These methods offer the following advantages: readily available and low-cost raw materials; highly controllable and reproducible polymerization processes; mild carbonization conditions, eliminating the need for complex equipment; and a powdered product that is easily processed and molded. Compared to the complex preparation processes and high costs of traditional metal or ferrite absorbers, this invention provides a novel, environmentally friendly, simple, and scalable carbon-based absorber preparation method, promising promising industrialization prospects.

[0041] 5. Excellent comprehensive performance, solving existing technical bottlenecks

[0042] At present, absorbing materials generally have problems such as a single loss mechanism, narrow absorption band, and complex preparation process. The present invention solves these problems from the source by combining molecular design with structural regulation. Specifically: the multi-element doping and microstructure design of the present invention bring about the synergistic effect of multiple loss mechanisms; impedance matching optimization allows electromagnetic waves to penetrate deeply into the interior of the material and be fully absorbed; the broadband response capability adapts to the electromagnetic interference protection needs of different frequency bands; and the simple and efficient preparation process supports large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0044] Figure 1 This is the infrared spectrum of ABHMA prepared in an embodiment of the present invention;

[0045] Figure 2 ABHMA prepared in the embodiment of the present invention 1 HNMR spectrum;

[0046] Figure 3 This is the infrared spectrum of the PDM prepared in the embodiment of the present invention;

[0047] Figure 4 The PDM prepared in the embodiment of the present invention 1 HNMR spectrum;

[0048] Figure 5 This is a scanning electron microscope image of the multi-element doped binary composite carbon material prepared in Examples 1-3 of the present invention;

[0049] Figure 6 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 1 of the present invention in the 2-18 GHz frequency band;

[0050] Figure 7 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 2 of the present invention in the 2-18 GHz frequency band;

[0051] Figure 8 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 3 of the present invention in the 2-18 GHz frequency band. DETAILED DESCRIPTION

[0052] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0053] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0054] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0055] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0056] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0057] The present invention discloses a method for preparing a multi-element doped binary composite carbon material, comprising the following steps:

[0058] (1) Preparation of ABHMA (sulfonic acid functional monomer)

[0059] 2-Hydroxy-4-methoxy-5-sulfonic acid benzophenone and N-hydroxymethyl acrylamide are added to a reaction vessel at a molar ratio of 1:1.0-1.5. Anhydrous ethanol is then added as the reaction solvent at a ratio of 30-40:100 of 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone per gram to ethanol per milliliter. The mixture is stirred and mixed thoroughly using an electric stirrer. Concentrated sulfuric acid is then slowly added at a ratio of 1:8-12 per milliliter to anhydrous ethanol per milliliter. The mixture is stirred and mixed thoroughly. An oil bath is then heated to a temperature of 35-40°C, where the reaction mixture is allowed to react for 3 days. After the reaction is complete, the mixture is cooled to room temperature and filtered. The filter cake is washed with deionized water until the filtrate is neutral. The resulting crude white powder is recrystallized from anhydrous ethanol to obtain ABHMA as white crystals.

[0060] (2) Preparation of PDM (bromine functional monomer)

[0061] Tetrabromobisphenol A and methacrylic anhydride are added in a molar ratio of 1:2.0-2.5. Acetone is then added at a ratio of 0.05-0.1:20-40 (milliliters) of tetrabromobisphenol A to acetone. Mix thoroughly using an electric stirrer. Then, p-toluenesulfonic acid (1.0-1.5:1 g of p-toluenesulfonic acid to 1.0-1.5 molar ratio of tetrabromobisphenol A) is added in three portions. Mix thoroughly. Heat the reaction mixture in an oil bath to 45-50°C and allow it to react at this temperature for one day. After the reaction is complete, cool the mixture to room temperature and filter. The filter cake is washed with deionized water until the filtrate is neutral. The resulting crude white powder is recrystallized from anhydrous ethanol to obtain PDM as white crystals.

[0062] (3) Preparation of P-ABHMA@PDM

[0063] ABHMA and PDM (2-4 g total mass) were weighed, with the molar ratios of sulfonic acid functional monomer to bromine functional monomer at 3:1, 1:1, and 1:3, and dissolved in a 9:1 volume ratio of acetonitrile to water (40-60 g solvent). Azobisisobutyronitrile (initiator) was then added at a ratio of 0.1-0.15:2 (grams of azobisisobutyronitrile to grams of monomers combined). The reaction was carried out at 70-75°C and stirred at 300 rpm for 3.0-3.5 hours. After the reaction, the solid product was separated by centrifugation and dried to obtain a multi-element doped binary composite copolymer (i.e., binary polymer).

[0064] (4) Preparation of CP-ABHMA@PDM

[0065] The binary composite copolymer powder was evenly spread on a crucible and placed in a vacuum tube furnace. High-purity nitrogen or argon was introduced at a rate of 200-300 mL / min to displace the air. A stepwise temperature control program was employed: pre-oxidation was performed by increasing the temperature at 1-2°C / min to 200°C and holding the temperature for 0.8-1.2 hours. Carbonization was then completed by increasing the temperature at 1-2°C / min to 700°C and holding the temperature for 1.5-2.5 hours. After the furnace temperature naturally dropped below 50°C, the product was removed, ground, and sieved to obtain the multi-element-doped binary composite carbon material.

[0066] Specifically, the present invention achieves a synergistic effect of multiple loss mechanisms through material composition adjustment and microstructure design, significantly improving the material's absorption performance. Regarding material design, ABHMA monomers and PDM monomers rich in heteroelements were prepared. The introduction of heteroatoms such as S / N / halogens provides more electron transfer pathways, enhancing the conductivity of the carbon material. Microstructure design is also crucial for optimizing microwave absorption performance. This invention leverages the differences in monomer functionality and adjusts the polymerization ratio between monomers to achieve structural design. The unique microstructure and rough surface of the carbon material promote multiple reflections and scattering of electromagnetic waves, helping to optimize impedance matching. This design overcomes the limitations of a single loss mechanism, simplifies the preparation process, and significantly improves absorption performance (minimum reflection loss = -55.25dB), providing new insights into the development of high-performance absorbing materials.

[0067] The raw materials used in the present invention are all purchased from the market.

[0068] The technical solution of the present invention is further illustrated by the following examples.

[0069] Example 1

[0070] A method for preparing a multi-element doped binary composite carbon material comprises the following steps:

[0071] (1) Preparation of ABHMA (sulfonic acid functional monomer)

[0072] Weigh 30.8 g (0.1 mol) of 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone and 12.2 g (0.12 mol) of N-hydroxymethyl acrylamide into a reaction vessel. Use 100 mL of anhydrous ethanol as the reaction solvent and stir thoroughly with an electric stirrer. Slowly add 10 mL of concentrated sulfuric acid dropwise in three portions. Heat the reaction mixture in an oil bath until the temperature reaches 38°C and react at this temperature for 3 days. After the reaction is complete, cool the solution to room temperature and filter it. Wash the filter cake with deionized water until neutral. The resulting crude white powder is recrystallized from anhydrous ethanol to obtain ABHMA as white crystals.

[0073]

[0074] (ABHMA)

[0075] (2) Preparation of PDM (bromine functional monomer)

[0076] Weigh 27.2 g (50 mmol) of tetrabromobisphenol A and 18.5 g (120 mmol) of methacrylic anhydride into a reaction vessel. Use 40 mL of acetone as the reaction solvent and stir thoroughly with an electric stirrer. Add 0.05 g (0.29 mmol) of p-toluenesulfonic acid. Heat the reaction mixture in an oil bath to 50°C and allow it to react at this temperature for 1 day. After the reaction is complete, cool the mixture to room temperature and filter it. Wash the filter cake with deionized water until neutral. The resulting crude white powder is recrystallized from anhydrous ethanol to obtain PDM as white crystals.

[0077]

[0078] (PDM)

[0079] (3) Preparation of P-ABHMA@PDM

[0080] 2 g of ABHMA and PDM were weighed, with a molar ratio of sulfonic acid functional monomer to bromine functional monomer of 3:1, and dissolved in 50 g of a 9:1 organic solvent mixture consisting of acetonitrile and water. 0.1 g of azobisisobutyronitrile (AIBN) was then added. The mixture was reacted at 75°C and stirred at 300 rpm for 3 h. After the reaction, the solid product was separated by centrifugation and dried to obtain a multi-element doped binary composite copolymer (denoted as P-ABHMA@PDM1).

[0081] (4) Preparation (carbonization) of CP-ABHMA@PDM

[0082] The binary composite copolymer powder was evenly spread onto a crucible and placed in a vacuum tube furnace. High-purity nitrogen or argon was introduced at 250 mL / min to displace the air. Pre-oxidation was performed by heating the crucible at a rate of 2°C / min to 200°C and holding the temperature for 1 hour. Carbonization was then completed by heating the crucible at the same rate to 700°C and holding the temperature for 2 hours. After the furnace temperature naturally dropped below 50°C, the product was removed, ground, and sieved to obtain a multi-element-doped binary composite carbon material (denoted as CP-ABHMA@PDM1).

[0083] Example 2

[0084] The difference from Example 1 is that

[0085] In step (3), the molar ratio of ABHMA to PDM is 1:1, and the binary composite copolymer prepared is P-ABHMA2@PDM;

[0086] The binary composite carbon material finally prepared in step (4) is CP-ABHMA@PDM2.

[0087] Other preparation processes and process parameters are the same as in Example 1.

[0088] Example 3

[0089] The difference from Example 1 is that

[0090] In step (3), the molar ratio of ABHMA to PDM is 1:3, and the binary composite copolymer prepared is P-ABHMA3@PDM;

[0091] The binary composite carbon material finally prepared in step (4) is CP-ABHMA@PDM3.

[0092] Other preparation processes and process parameters are the same as in Example 1.

[0093] Figure 1 This is the infrared spectrum of ABHMA prepared in an embodiment of the present invention, and its infrared absorption peak characterization data are as follows: IR (KBr) v: CH (benzene ring bending vibration): 833.32, CN: 1028.48, SO (sulfonic acid group stretching vibration): 1169.50, CO (methoxyl stretching vibration): 1222.20, S=O (sulfonic acid group asymmetric stretching) 1270.64, C=C (benzene ring skeleton vibration): 1447.27, 1539.87, 1602.54, C=O (secondary amide I band): 1668.07, C=O (carbonyl stretching vibration): 1749.26, NH: 3061.21, OH: 3294.83, SO3-H: 3475.74 cm -1 .

[0094] Figure 2 ABHMA prepared in the embodiment of the present invention 1 HNMR diagram, its nuclear magnetic resonance peak characterization data are as follows: 1 HNMR (DMSO-d6, 600MHz) δ: 3.85 (s, 3H, -OCH3), 4.31 (t, 2H, -CH2), 5.77 (m, 1H, =CH), 6.25 (m, 1H, =CH2), 6.31 (m, 1H, =CH2), 7.57 (m, 2H, Ph-H), 7.63 (m, 3H,Ph-H), 7.93 (s, 1H, Ph-H), 9.08 (t, 1H, -NH), 12.24 (s, 1H, -OH). Depend on Figure 1 and Figure 2 It can be seen that ABHMA was successfully prepared.

[0095] Figure 3This is an infrared spectrum of the PDM prepared in an embodiment of the present invention. The infrared absorption peak characterization data are as follows: IR (KBr) v: C-Br: 613.95, 730.76, CH (benzene ring bending vibration): 867.51, C=C (benzene ring skeleton vibration): 1471.49, 1554.11, C=O (carbonyl stretching vibration): 1736.44, CH (methyl stretching vibration): 3001.84 cm -1 .

[0096] Figure 4 The PDM prepared in the embodiment of the present invention 1 HNMR diagram, its nuclear magnetic resonance peak characterization data are as follows: 1 HNMR(DMSO-d6, 600MHz)δ: 1.85 (s, 6H, -CH3), 2.05 (s, 6H, -CH3), 5.61 (m, 2H, =CH2), 5.99 (m, 2H, =CH2), 7.34 (d, 2H, Ph-H), 7.63 (d, 2H, Ph-H). Depend on Figure 3 and Figure 4 It can be seen that PDM was successfully prepared.

[0097] Figure 5 Scanning electron micrographs of the multi-element-doped binary composite carbon materials prepared in Examples 1-3 of the present invention show that the microscopic morphologies of CP-ABHMA@PDM1 (Example 1), CP-ABHMA@PDM2 (Example 2), and CP-ABHMA@PDM3 (Example 3) are spherical, French fry, and popcorn-shaped, respectively.

[0098] Effect verification

[0099] Wave absorption performance test

[0100] 0.025 g of carbonized CP-ABHMA@PDM was weighed and mixed with 0.125 g of paraffin wax in a 2 mL centrifuge tube. The tube was secured to a foam holder and placed in an ultrasonic cleaner preheated to 80°C. Ultrasonic vibration was activated to melt the paraffin and thoroughly mix it with the sample. The mixture was then injected into a mold and dispersed using a sealed capillary tube during a secondary ultrasonic treatment. After cooling to a semi-solid state at room temperature, the mold was pressed into shape. During the electromagnetic testing phase, the waveguide system components of the vector network analyzer were thoroughly cleaned with an alcohol pad. After installing the concentric ring sample, the instrument was calibrated. After securely connecting the test system, the 2-18 GHz test frequency band was set. At least two repeated measurements were performed on both the front and back sides of the sample to ensure data reliability, ultimately completing the quantitative analysis of electromagnetic reflection loss. Figure 6-8It is the reflection loss of multi-element doped binary composite carbon materials in the frequency range of 2 to 18 GHz.

[0101] Figure 6 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 1 of the present invention in the 2-18 GHz frequency band.

[0102] Figure 7 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 2 of the present invention in the 2-18 GHz frequency band.

[0103] Figure 8 2D reflection loss graph (a) and 3D reflection loss graph (b) of the multi-element doped binary composite carbon material prepared in Example 3 of the present invention in the 2-18 GHz frequency band.

[0104] Depend on Figure 6-8 It can be seen that over a wide frequency range of 2 to 18 GHz, the CP-ABHMA@PDM composite material co-doped with three heteroatoms, N, S, and Br, exhibits excellent electromagnetic wave absorption performance, with a minimum reflection loss (RL min) exceeding -34 dB throughout. This breakthrough performance is attributed to the synergistic effect of heteroatom doping and the optimized impedance matching. Notably, the French-chip-shaped CP-ABHMA@PDM2 achieves an RL min of -55.25 dB at 7.4 GHz. This is a 37.4% and 22.5% improvement over the spherical (RL min = -34.58 dB) and popcorn-shaped (RL min = -42.90 dB) materials of the same series, respectively. Microstructural analysis reveals that electromagnetic waves may undergo multiple reflection paths during penetration, ultimately achieving efficient dissipation of electromagnetic wave energy.

[0105] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a multi-element doped binary composite carbon material, characterized in that: The following steps are involved: The sulfonic acid functional monomer is prepared by alkylation reaction of 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone and N-hydroxymethyl acrylamide; A bromine functional monomer is prepared by esterification of tetrabromobisphenol A, methacrylic anhydride and p-toluenesulfonic acid; The sulfonic acid functional monomer and the bromine functional monomer are subjected to a free radical polymerization reaction to prepare a binary polymer; Carbonizing the binary polymer to prepare the multi-element doped binary composite carbon material; The molar ratio of the 2-hydroxy-4-methoxy-5-sulfonic acid benzophenone to N-hydroxymethyl acrylamide is 1: (1.0-1.5).

2. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The alkylation reaction was carried out at 35-40° C. for 3 days.

3. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The molar ratio of the p-toluenesulfonic acid, tetrabromobisphenol A and methacrylic anhydride is (0.005-0.01):1:(2.0-2.5).

4. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The esterification reaction was carried out at 45-50° C. for 1 day.

5. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The molar ratio of the sulfonic acid functional monomer to the bromine functional monomer is (1:3)-(3:1).

6. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The free radical polymerization reaction conditions are: reaction at 70-75° C. and stirring speed of 300 rpm for 3.0-3.5 hours.

7. The method for preparing a multi-element doped binary composite carbon material according to claim 1, characterized in that: The carbonization is a staged carbonization, specifically: First, heat the sample to 200 °C at a heating rate of 1-2 °C / min and maintain the temperature for 0.8-1.2 h. Then, the temperature was raised to 700 °C at a heating rate of 1 to 2 °C / min and maintained at this temperature for 1.5 to 2.5 h.

8. A multi-element doped binary composite carbon material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the multi-element doped binary composite carbon material according to claim 8 in the field of electromagnetic wave absorption.

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