A boron-doped magnetic porous carbon wave-absorbing material and a preparation method thereof

Abstract

The application relates to a boron-doped magnetic porous carbon wave-absorbing material and a preparation method thereof, and belongs to the technical field of electromagnetic wave absorbing materials. The method comprises the following steps: synthesizing an iron-containing super-crosslinked porous polymer through a Friedel-Crafts reaction; mixing a boron dopant with the iron-containing super-crosslinked porous polymer uniformly; and placing the mixture in a tube furnace to perform high-temperature carbonization, so as to obtain the boron-doped magnetic porous carbon wave-absorbing material. The preparation method is simple, the cost is low, the porous structure increases the reflection path of electromagnetic waves, the magnetic component provides magnetic loss and forms a heterojunction with the carbon component to provide interface polarization, the doped boron atoms improve the dipole polarization capacity of the material, through the joint action of the loss mechanisms, the excellent performance of strong absorption and wide frequency band is achieved, meanwhile, the porous structure significantly reduces the density of the material, and a new idea is provided for the preparation of light, wide-frequency and high-efficiency wave-absorbing materials.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorbing materials technology, and relates to lightweight porous carbon wave absorbing materials and their preparation methods, specifically to a boron-doped magnetic porous carbon wave absorbing material and its preparation method. Background Technology

[0002] Electromagnetic energy propagates outward in the form of waves without returning to its source; this is called electromagnetic radiation. Natural phenomena such as atmospheric lightning, cosmic rays, and solar and terrestrial thermal radiation generate natural electromagnetic radiation. Man-made electromagnetic radiation is produced by industrial electronic and electrical equipment and various consumer electronic products. The disordered and intense radiation of these electromagnetic waves causes electromagnetic pollution. Electromagnetic radiation has become a new and highly harmful source of pollution, following water pollution, air pollution, and noise pollution. It not only affects normal communication but also directly threatens human health, becoming a hot topic of concern for society and the scientific community. Electromagnetic wave absorbing materials are functional materials that can convert the energy of incident electromagnetic waves into heat or other forms of energy through electromagnetic loss, and are a key material for solving electromagnetic radiation pollution.

[0003] Traditional microwave absorbing materials are mainly classified into two types according to their loss mechanism: electrical loss and magnetic loss. (1) Electrical loss type microwave absorbing materials can be further subdivided into dielectric type microwave absorbing materials and resistive type microwave absorbing materials. Dielectric type microwave absorbing materials, represented by barium titanate and silicon carbide, absorb through repeated polarization of the medium, which converts electromagnetic energy into heat energy and dissipates it. Resistive type microwave absorbing materials, represented by carbon fiber and carbon nanotubes, absorb through the mechanism that the conductive charge carriers inside the material move in a directional manner under the action of an electric field to form a conduction current, which causes electromagnetic energy to be lost in the form of heat energy. (2) Magnetic loss type microwave absorbing materials, represented by ferrite and carbonyl iron, achieve the purpose of microwave absorption by converting electromagnetic energy into heat energy during the magnetization and demagnetization process.

[0004] Electrically depleted microwave absorbing materials are widely used in the preparation of lightweight microwave absorbing materials due to their low density, but they suffer from poor impedance matching and weak absorption intensity. While magnetically depleted microwave absorbing materials offer advantages such as low cost, ease of preparation, and strong absorption, their high density and narrow absorption bandwidth limit their further development in the field of microwave absorbing materials. Given these issues, traditional microwave absorbing materials cannot meet the current development requirements for "thin, light, wide, and strong" microwave absorbing materials. Therefore, the development of novel microwave absorbing agents increasingly leans towards obtaining composite microwave absorbing agents through the construction of multi-component complex structures. Summary of the Invention

[0005] The purpose of this invention is to address the problem that traditional microwave absorbing materials cannot meet the current development requirements for "thin, light, wide, and strong" microwave absorbing materials, and to provide a boron-doped magnetic porous carbon microwave absorbing material and its preparation method. The prepared microwave absorbing material exhibits multiple loss mechanisms and also has the advantages of low density, wide absorption bandwidth, simple preparation method, and low raw material cost.

[0006] This invention combines porous carbon materials with iron and its oxides to enhance impedance matching, allowing as many electromagnetic waves as possible to penetrate the material. Simultaneously, boron atoms are incorporated into the carbon lattice to adjust the electronic structure of adjacent carbon atoms, enhancing polarization loss. The synergistic effect of multiple loss mechanisms within the composite material significantly improves the attenuation capability of incident electromagnetic waves.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a boron-doped magnetic porous carbon microwave absorbing material, wherein the method uses an iron-containing hypercrosslinked porous polymer as a porous carbon framework precursor, and incorporates boron into the carbon lattice during carbonization.

[0009] Furthermore, the method includes the following steps:

[0010] Step 1: Friedel-Crafts reaction synthesis of iron-containing hypercrosslinked porous polymer: Under nitrogen atmosphere, monomers, crosslinking agents, and catalyst anhydrous ferric chloride are mixed in a solvent and subjected to a Friedel-Crafts reaction to prepare iron-containing hypercrosslinked porous polymer;

[0011] Step 2: High-temperature carbonization preparation of boron-doped magnetic porous carbon absorbing material: Under nitrogen atmosphere, the boron dopant is mixed evenly with an iron-containing hypercrosslinked porous polymer and then placed in a tube furnace for high-temperature carbonization to obtain boron-doped magnetic porous carbon absorbing material.

[0012] Further, step one specifically involves: under nitrogen atmosphere, dissolving 1-3 molar amounts of monomer, 1-4 molar amounts of crosslinking agent, and 2-10 molar amounts of catalyst anhydrous ferric chloride in a reaction solvent; dividing the reaction temperature into three stages: the first temperature stage is 30-50℃, the second temperature stage is 50-70℃, and the third temperature stage is 70-90℃, with each temperature stage reacting for 20-28 hours; after the reaction is completed, the mixture is filtered, and the filter cake is dried in a vacuum oven at 60℃ for 6-8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0013] Further, in step one, the monomer is one or more of naphthalene, anthracene, phenanthrene, pyrene, biphenyl, terphenyl, o-diphenylbenzene, triphenylbenzene, and tetraphenylmethane; the crosslinking agent is one or more of dimethoxymethane, 1,3,5-tris(chloromethyl)benzene, 1,3,5-tris(chloromethyl)-2,4,6-trimethylbenzene, p-dichlorobenzyl, and biphenyl dichlorobenzyl; and the solvent is one of 1,2-dichloroethane and carbon tetrachloride.

[0014] Further, step two specifically involves: dispersing 1-4 parts by weight of an iron-containing hypercrosslinked porous polymer and 0.5-4 parts by weight of a boron dopant in a liquid medium, stirring at room temperature for 30-40 minutes to ensure uniform mixing, collecting by centrifugation, and drying in a vacuum oven at 60°C for 6-8 hours; transferring the dried powder to a ceramic boat and placing it in a tube furnace, under nitrogen conditions, setting the heating rate to 3-8°C / min, the carbonization temperature to 650-850°C, and the carbonization time to 1-3 hours, to obtain a boron-doped magnetic porous carbon microwave absorbing material.

[0015] Furthermore, the boron dopant is one or more of elemental boron, boric acid, and boron trioxide.

[0016] Furthermore, the liquid medium is one or more of deionized water, anhydrous ethanol, and anhydrous methanol.

[0017] A boron-doped magnetic porous carbon microwave absorbing material prepared by the above preparation method.

[0018] The advantages of this invention compared to existing technologies are as follows: This invention utilizes the Friedel-Crafts reaction to synthesize a hypercrosslinked polymer with a stable porous structure. Ferric chloride not only serves as a highly active Lewis acid catalyst to promote monomer polymerization but also as an iron source during the carbonization process. The iron-containing hypercrosslinked porous polymer is uniformly mixed with a boron dopant and then subjected to high-temperature carbonization. The hypercrosslinked porous framework is sintered into a porous carbon structure. The graphitic carbon in the porous carbon structure increases the material's conductivity and improves conductive loss. Simultaneously, the porous structure not only facilitates multiple reflections and interfacial polarization but also significantly reduces the material's density. Boron atoms, with atomic radii similar to carbon, readily enter the carbon lattice. Boron doping adjusts the electronic structure of adjacent carbon atoms, enhancing dipole polarization. Trivalent iron is converted into elemental iron and its oxides, providing magnetic loss, and the charge redistribution at the carbon interface induces interfacial polarization. In summary, this invention offers a simple preparation method with low cost. By improving the coordination among multiple loss mechanisms, it achieves excellent performance with strong absorption and a wide bandwidth, while significantly reducing the material's density, demonstrating promising application prospects. Attached Figure Description

[0019] Figure 1This is a nitrogen adsorption-desorption curve of the boron-doped magnetic porous carbon microwave absorbing material of Embodiment 1 of the present invention.

[0020] Figure 2 This is a pore size distribution curve of the boron-doped magnetic porous carbon microwave absorbing material of Embodiment 1 of the present invention;

[0021] Figure 3 This is a scanning electron microscope image of the boron-doped magnetic porous carbon microwave absorbing material of Embodiment 1 of the present invention;

[0022] Figure 4 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material of Embodiment 1 of the present invention;

[0023] Figure 5 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material of Embodiment 2 of the present invention;

[0024] Figure 6 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material in Embodiment 3 of the present invention;

[0025] Figure 7 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material in Embodiment 4 of the present invention;

[0026] Figure 8 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material in Embodiment 5 of the present invention;

[0027] Figure 9 This is a reflection loss curve of the boron-doped magnetic porous carbon absorbing material of Embodiment 6 of the present invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings.

[0029] The present invention and its embodiments are described below. This description is not restrictive, and actual embodiments are not limited thereto. In short, if those skilled in the art are inspired by this description and, without departing from the spirit of the invention, design similar structures and embodiments to this technical solution, such designs should fall within the protection scope of the present invention.

[0030] The preparation method of this invention is simple and low-cost. The porous structure increases the reflection path of electromagnetic waves, the magnetic component provides magnetic loss and forms a heterogeneous interface with the carbon component to provide interfacial polarization, and the doped boron atoms improve the dipole polarization capability of the material. Through the combined effect of these loss mechanisms, excellent performance of strong absorption and wide bandwidth is achieved. At the same time, the porous structure significantly reduces the density of the material, providing a new approach for the preparation of lightweight, broadband and high-efficiency microwave absorbing materials.

[0031] Example 1:

[0032] Step 1: Under nitrogen atmosphere, dissolve 1 part phenanthrene, 3 parts p-dichlorobenzyl, and 2 parts anhydrous ferric chloride in 80 ml of 1,2-dichloroethane. Heat the reaction system to the first temperature range of 45°C and react for 20 hours. Then heat the reaction system to the second temperature range of 65°C and react for 20 hours. Continue heating the reaction system to the third temperature range of 80°C and react for 20 hours. After the reaction is completed, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6-8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0033] Step 2: Disperse 1 part by weight of iron-containing hypercrosslinked porous polymer and 2 parts by weight of boric acid in anhydrous ethanol, stir at room temperature for 30-40 minutes to make it uniformly mixed, collect by centrifugation, and dry in a vacuum oven at 60℃ for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 4℃ / min, the carbonization temperature to 720℃, and the carbonization time to 3 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0034] Figure 1 This is a nitrogen adsorption-desorption curve of the boron-doped magnetic porous carbon microwave absorbing material in Example 1, according to the IUPAC classification. Figure 1 It exhibits a typical Type IV isotherm and a distinct hysteresis loop in the medium-pressure region, indicating mesoporous properties. Furthermore, the specific surface area reaches 597.88 m². 2 / g, BJH pore volume is 0.59cm³. 3 / g. Figure 2 The graph shows the pore size distribution of the boron-doped magnetic porous carbon microwave absorbing material in Example 1. The pore size is mainly distributed at 3.93 nm, which proves that the sample in Example 1 has a porous structure. Figure 3 The image shown is a scanning electron microscope (SEM) image of the boron-doped magnetic porous carbon microwave absorbing material from Example 1. The carbonized sample exhibits a flower-like morphology, and abundant pores are clearly visible. The porous structure not only provides the composite material with a large specific surface area and total pore volume, but also generates multiple reflections and scattering to dissipate energy, converting microwave energy into heat or other forms of energy during long-term propagation. Furthermore, the porous structure also helps reduce the density of the absorbing material. Figure 4 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 1. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 2.40 mm, the minimum reflection loss is -50.54 dB, the effective absorption frequency range is 10.64 to 18.00 GHz, and the effective absorption bandwidth is 7.36 GHz.

[0035] Example 2:

[0036] Step 1: Under nitrogen atmosphere, dissolve 2 parts anthracene, 1 part biphenyl dichlorobenzyl, and 3 parts anhydrous ferric chloride in 80 ml of 1,2-dichloroethane. Heat the reaction system to the first temperature range of 48°C and react for 22 hours. Then heat the system to the second temperature range of 68°C and react for 22 hours. Continue heating the system to the third temperature range of 75°C and react for 26 hours. After the reaction is complete, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6-8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0037] Step 2: Disperse 1 part by weight of iron-containing hypercrosslinked porous polymer and 1 part by weight of boric acid in deionized water, stir at room temperature for 30-40 minutes to make it uniformly mixed, collect by centrifugation, and dry in a vacuum oven at 60℃ for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 4℃ / min, the carbonization temperature to 720℃, and the carbonization time to 3 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0038] Figure 5 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 2. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 3.50 mm, the minimum reflection loss is -47.51 dB, the effective absorption frequency range is 11.52 to 18.00 GHz, and the effective absorption bandwidth is 6.48 GHz.

[0039] Example 3:

[0040] Step 1: Under nitrogen atmosphere, dissolve 1 part triphenylbenzene, 2 parts biphenyl dichlorobenzyl, and 4 parts anhydrous ferric chloride in 80 ml of 1,2-dichloroethane. Heat the reaction system to the first temperature range of 45°C and react for 20 hours. Then heat the reaction system to the second temperature range of 65°C and react for 20 hours. Continue heating the reaction system to the third temperature range of 80°C and react for 20 hours. After the reaction is completed, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6-8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0041] Step 2: Disperse 1 part by weight of iron-containing supercrosslinked porous polymer and 3 parts by weight of boron trioxide in deionized water, stir at room temperature for 30-40 minutes to make it uniformly mixed, collect by centrifugation, and dry in a vacuum oven at 60℃ for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 6℃ / min, the carbonization temperature to 750℃, and the carbonization time to 2 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0042] Figure 6 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 3. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 2.20 mm, the minimum reflection loss is -38.68 dB, the effective absorption frequency range is 12.00 to 18.00 GHz, and the effective absorption bandwidth is 6.60 GHz.

[0043] Example 4:

[0044] Step 1: Under nitrogen atmosphere, dissolve 2 parts biphenyl, 1 part dimethoxymethane, and 5 parts anhydrous ferric chloride in 80 ml of carbon tetrachloride. Heat the reaction system to the first temperature range of 40°C and react for 20 hours. Then heat the system to the second temperature range of 65°C and react for 25 hours. Finally, heat the system to the third temperature range of 75°C and react for 20 hours. After the reaction is complete, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6–8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0045] Step 2: Disperse 1 part by weight of iron-containing hypercrosslinked porous polymer and 1 part by weight of elemental boron in anhydrous methanol, stir at room temperature for 30-40 minutes to mix evenly, collect by centrifugation, and dry in a vacuum oven at 60°C for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 6°C / min, the carbonization temperature to 750°C, and the carbonization time to 2 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0046] Figure 7 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 4. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 3.50 mm, the minimum reflection loss is -38.70 dB, the effective absorption frequency range is 11.52 to 18.00 GHz, and the effective absorption bandwidth is 6.48 GHz.

[0047] Example 5:

[0048] Step 1: Under nitrogen atmosphere, dissolve 2 parts tetraphenylmethane, 1 part 1,3,5-tris(chloromethyl)-2,4,6-trimethylbenzene, and 6 parts anhydrous ferric chloride in 100 ml of 1,2-dichloroethane. Heat the reaction system to the first temperature range of 40°C and react for 20 hours. Then heat the system to the second temperature range of 65°C and react for 24 hours. Continue heating the system to the third temperature range of 75°C and react for 22 hours. After the reaction is complete, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6–8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0049] Step 2: Disperse 1 part by weight of iron-containing hypercrosslinked porous polymer and 1.5 parts by weight of elemental boron in anhydrous methanol, stir at room temperature for 30-40 minutes to mix evenly, collect by centrifugation, and dry in a vacuum oven at 60°C for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 6°C / min, the carbonization temperature to 720°C, and the carbonization time to 2 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0050] Figure 8 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 5. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 2.20 mm, the minimum reflection loss is -38.67 dB, the effective absorption frequency range is 12.00 to 18.00 GHz, and the effective absorption bandwidth is 6.00 GHz.

[0051] Example 6:

[0052] Step 1: Under nitrogen atmosphere, dissolve 2 parts o-diphenylbenzene, 1 part dimethoxymethane, and 10 parts anhydrous ferric chloride in 90 ml of carbon tetrachloride. Heat the reaction system to the first temperature range of 40°C and react for 20 hours. Then heat the reaction system to the second temperature range of 65°C and react for 20 hours. Continue heating the reaction system to the third temperature range of 75°C and react for 24 hours. After the reaction is completed, filter the mixture and dry the filter cake in a vacuum oven at 60°C for 6-8 hours to obtain an iron-containing hypercrosslinked porous polymer.

[0053] Step 2: Disperse 1 part by weight of iron-containing hypercrosslinked porous polymer and 2.5 parts by weight of elemental boron in anhydrous methanol, stir at room temperature for 30-40 minutes to mix evenly, collect by centrifugation, and dry in a vacuum oven at 60°C for 6-8 hours; transfer the dried powder to a ceramic boat and place it in a tube furnace, under nitrogen conditions, set the heating rate to 5°C / min, the carbonization temperature to 700°C, and the carbonization time to 2 hours to obtain boron-doped magnetic porous carbon microwave absorbing material.

[0054] Figure 9 The diagram shows the reflection loss of boron-doped magnetic porous carbon in Example 6. When the filling ratio is 30%, it has the best electromagnetic wave absorption effect with a matching thickness of 2.20 mm, the minimum reflection loss is -29.61 dB, the effective absorption frequency range is 12.24 to 18.00 GHz, and the effective absorption bandwidth is 5.76 GHz.

[0055] Table 1 summarizes the electromagnetic absorption performance of Examples 1-6. The test results show that the magnetic porous carbon lightweight absorbing material formed by incorporating boron into the carbon lattice during carbonization, using an iron-containing hypercrosslinked porous polymer as the porous carbon framework precursor, exhibits excellent microwave absorption performance. Among them, Example 1 demonstrates the best overall microwave absorption performance, exhibiting a minimum reflection loss of -50.54 dB and an effective absorption bandwidth of 7.36 GHz when the filler ratio is 30%. This sample possesses high absorption intensity, wide absorption bandwidth, low density, and thin matching thickness, meeting the current development requirements for "thin, light, wide, and strong" absorbing materials.

[0056] Table 16 Electromagnetic wave absorption performance of the samples from the examples

[0057]

Claims

1. A method for preparing a boron-doped magnetic porous carbon microwave absorbing material, characterized in that: The method uses an iron-containing hypercrosslinked porous polymer as a porous carbon framework precursor, and incorporates boron into the carbon lattice during carbonization. The method includes the following steps: Step 1: Friedel-Crafts reaction synthesis of iron-containing hypercrosslinked porous polymer: Under nitrogen atmosphere, monomers, crosslinking agents, and anhydrous ferric chloride catalyst are mixed in a solvent and subjected to a Friedel-Crafts reaction to prepare an iron-containing hypercrosslinked porous polymer. Specifically, under nitrogen atmosphere, 1-3 molar parts of monomer, 1-4 molar parts of crosslinking agent, and 2-10 molar parts of anhydrous ferric chloride catalyst are dissolved in the reaction solvent. The reaction temperature is divided into three stages: the first temperature stage is 30-50 ℃, the second temperature stage is 50-70 ℃, and the third temperature stage is 70-90 ℃, with each temperature stage reacting for 20-28 hours. After the reaction, the mixture is filtered, and the filter cake is dried in a vacuum oven at 60 ℃ for 6-8 hours to obtain the iron-containing hypercrosslinked porous polymer. Step 2: High-temperature carbonization preparation of boron-doped magnetic porous carbon absorbing material: Under nitrogen atmosphere, the boron dopant is mixed evenly with an iron-containing hypercrosslinked porous polymer and then placed in a tube furnace for high-temperature carbonization to obtain boron-doped magnetic porous carbon absorbing material.

2. The method for preparing a boron-doped magnetic porous carbon microwave absorbing material according to claim 1, characterized in that: In step one, the monomer is one or more of naphthalene, anthracene, phenanthrene, pyrene, biphenyl, terphenyl, o-diphenylbenzene, triphenylbenzene, and tetraphenylmethane; the crosslinking agent is one or more of dimethoxymethane, 1,3,5-tris(chloromethyl)benzene, 1,3,5-tris(chloromethyl)-2,4,6-trimethylbenzene, p-dichlorobenzyl, and biphenyl dichlorobenzyl; and the solvent is one of 1,2-dichloroethane and carbon tetrachloride.

3. The method for preparing a boron-doped magnetic porous carbon microwave absorbing material according to claim 1, characterized in that: Step two specifically involves dispersing 1-4 parts by weight of an iron-containing hypercrosslinked porous polymer and 0.5-4 parts by weight of a boron dopant in a liquid medium, stirring at room temperature for 30-40 minutes to ensure uniform mixing, collecting by centrifugation, and drying in a vacuum oven at 60 ℃ for 6-8 hours; transferring the dried powder to a ceramic boat and placing it in a tube furnace, under nitrogen conditions, setting the heating rate to 3-8 ℃ / min, the carbonization temperature to 650-850 ℃, and the carbonization time to 1-3 hours to obtain a boron-doped magnetic porous carbon microwave absorbing material.

4. A method for preparing a boron-doped magnetic porous carbon microwave absorbing material according to claim 1 or 3, characterized in that: The boron dopant is one or more of elemental boron, boric acid, and boron trioxide.

5. The method for preparing a boron-doped magnetic porous carbon microwave absorbing material according to claim 3, characterized in that: The liquid medium is one or more of deionized water, anhydrous ethanol, and anhydrous methanol.

6. A boron-doped magnetic porous carbon microwave absorbing material prepared by the preparation method according to any one of claims 1 to 5.

Images