A MOF-derived wood-based porous carbon wave-absorbing material and a preparation method thereof

Abstract

The application discloses a MOF-derived wood-based porous carbon-based wave-absorbing material and a preparation method thereof, and comprises the following steps: placing Balsha wood in a flask, adding distilled water, heating, adding acetic acid and sodium chlorite, adding an equal amount of acetic acid and sodium chlorite after reaction, repeating the adding for three times, and washing and drying; dissolving cobalt nitrate hexahydrate and nickel nitrate hexahydrate in ethanol, placing the wood after removing lignin in the ethanol solution, and adding dropwise an ethanol solution containing 2-methyl imidazole; after the dropwise adding is completed, drying; and calcining and carbonizing the dried wood under the protection of inert gas. The wood is used as a matrix, the wood has a regular, fine and hollow and straight pore structure, a certain amount of cobalt nitrate hexahydrate and nickel nitrate hexahydrate are loaded, and 2-methyl imidazole is coordinated to synthesize nickel and cobalt MOF, and the MOF-derived wood-based porous carbon-based wave-absorbing material with good electromagnetic wave absorption capacity can be prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave absorbing materials, and in particular to a MOF-derived wood-based porous carbon absorbing material and a preparation method thereof. Background Art

[0002] Carbon-based materials (carbon nanotubes, graphene, carbon spheres, porous carbon, carbon fibers, and carbon quantum dots) have become promising absorbers due to their low density, high dielectric loss, excellent chemical stability, high conductivity, and ease of modification. However, single-component carbon-based absorbers suffer from a single loss mechanism and poor impedance matching, resulting in weak absorption strength and a narrow absorption bandwidth. Magnetic particles (such as Fe, Co, Ni, and their oxides) are often introduced to improve impedance matching and enhance absorption performance. In the past decade, researchers have developed three-dimensional porous carbon-based materials based on zero-dimensional, one-dimensional, and two-dimensional carbon-based absorbers, demonstrating even superior overall performance. The unique micro- and nanopore structures of three-dimensional porous materials result in a high specific surface area. Electromagnetic waves undergo multiple reflections and scattering within these materials, inducing greater interfacial polarization losses and further enhancing the material's absorption performance. Among them, Metal-Organic Framework (MOFs) is a porous material formed by metal ions or ion clusters and organic ligands through molecular self-assembly. It has the characteristics of ultra-large specific surface area, regular pores and adjustable structure. The metal and organic components and adjustable microstructures in MOFs can be used to in situ construct metal / metal oxide three-dimensional porous carbon-based materials. The graphite layer formed by carbonization can produce conductivity loss. The coordination between metal / metal oxide nanoparticles and carbon matrix can regulate dielectric loss and magnetic loss, constructing suitable impedance matching. The core-shell structure within the particles can also produce interface polarization loss and multiple reflection loss. These factors contribute to the performance and effective absorption bandwidth of porous carbon-based absorbers. However, MOF-derived carbon-based absorbers currently have the following problems: (1) low preparation efficiency; (2) organic ligands are synthesized by chemical methods; (3) the crystal structure is difficult to control. These factors limit the application of MOF-derived carbon-based absorbers. Therefore, exploring new microstructures and developing simple, low-cost, efficient and mass-produced processes for preparing MOFs carbon-based absorbing materials are issues that need to be addressed in order to achieve their industrial application.

[0003] In view of this, this application is hereby filed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the current preparation efficiency of MOFs-derived carbon-based absorbing materials is low, the organic ligands are synthesized by chemical means, and the crystal structure is difficult to control. The purpose is to provide a MOF-derived wood-based porous carbon-based absorbing material and a preparation method thereof. Wood, which is low-cost, widely available, and easily available, is used as a matrix. Nickel and cobalt MOFs are synthesized by loading a certain amount of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and coordinating with 2-methylimidazole. A MOF-derived wood-based porous carbon-based absorbing material with good electromagnetic wave absorption ability can be obtained. The preparation process is simple, environmentally friendly, low-cost, and can be widely used.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material comprises the following steps:

[0007] The steps include:

[0008] (1) Lignin removal: Place a certain amount of balsa wood in a round-bottom flask, add distilled water, heat to a certain temperature, add acetic acid and sodium chlorite, add equal amounts of acetic acid and sodium chlorite after the reaction, repeat the addition three times, and then wash and dry;

[0009] (2) Adsorption of MOF: A certain amount of cobalt nitrate hexahydrate and nickel nitrate hexahydrate were dissolved in ethanol. The wood after the lignin removal in step (1) was placed in the ethanol solution, and then the ethanol solution containing 2-methylimidazole was added dropwise. After the addition was completed, the mixture was left for 24 hours, and then the wood was dried.

[0010] (3) The dried wood is placed in a tubular furnace and calcined and carbonized under the protection of inert gas. After cooling, MOF-derived wood porous carbon-based absorbing materials are obtained.

[0011] In one or more embodiments, in step (1), the temperature for heating to remove delignification is 65-80°C.

[0012] In one or more embodiments, in step (2), the mass ratio of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) to nickel nitrate hexahydrate (Ni(NO3)2·6H2O) is 3:10 to 7:10.

[0013] In one or more embodiments, in step (2), the mass ratio of 2-methylimidazole to delignified wood is 5:1 to 1:1.

[0014] In one or more embodiments, in step (3), the carbonization temperature is 600-900°C.

[0015] In one or more embodiments, in step (3), the carbonization time is 1 to 1.2 h.

[0016] In one or more embodiments, in step (3), the heating rate is 5°C / min.

[0017] In one or more embodiments, in step (3), nitrogen is used as the inert gas.

[0018] The present invention also provides a MOF-derived wood-based porous carbon-based absorbing material, which is prepared using the above-mentioned preparation method.

[0019] The present invention also provides the application of the MOF-derived wood-based porous carbon-based absorbing material prepared by the above preparation method in the field of electromagnetic wave absorption.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. The present invention provides a MOF-derived wood-based porous carbon absorbing material and a preparation method thereof. Wood, which has a regular, fine, hollow, straight pore structure, is used as a matrix. A certain amount of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and nickel nitrate hexahydrate (Ni(NO3)2·6H2O) are loaded and coordinated with 2-methylimidazole to synthesize nickel and cobalt MOFs. This MOF-derived wood-based porous carbon absorbing material with good electromagnetic wave absorption capacity can be produced. This material has good development prospects in the field of constructing electromagnetic wave absorbing materials. Furthermore, the preparation process is simple, environmentally friendly, and low-cost, making it widely applicable.

[0022] 2. An embodiment of the present invention provides a MOF-derived wood-based porous carbon absorbing material and a preparation method thereof. The carbonized wood can form porous carbon, which allows electromagnetic waves to enter the material for multiple scattering and reflection, and also reduces the density of the electromagnetic absorbing material. At the same time, the carbonization temperature is used to regulate the degree of graphitization of the porous carbon and thus the dielectric loss. Nickel and cobalt magnetic particles are loaded in the porous carbon. This porous structure and magnetic particles give the carbon-based material a dual loss mechanism of dielectric and magnetic loss, which can effectively improve the absorbing performance of the MOF-derived wood carbon-based porous material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without making any creative efforts.

[0024] Figure 1This is a reflection loss diagram of the electromagnetic wave absorbing material in Example 1 of the present invention in the 2-18 GHz frequency band;

[0025] Figure 2 This is an SEM image of the MOF-derived wood porous carbon-based absorbing material in Example 1 of the present invention;

[0026] Figure 3 This is a TEM image of the MOF-derived wood porous carbon-based absorbing material in Example 1 of the present invention;

[0027] Figure 4 This is a reflection loss diagram of the electromagnetic wave absorbing material in Example 2 of the present invention in the 2-18 GHz frequency band;

[0028] Figure 5 This is a reflection loss diagram of the electromagnetic wave absorbing material in Example 3 of the present invention in the 2-18 GHz frequency band;

[0029] Figure 6 Graph showing reflection loss of the electromagnetic wave absorbing material in Comparative Example 1 of the present invention within the 2-18 GHz frequency band;

[0030] Figure 7 This is a reflection loss diagram of the electromagnetic wave absorbing material in Comparative Example 2 of the present invention in the 2-18 GHz frequency band;

[0031] Figure 8 This is a reflection loss diagram of the electromagnetic wave absorbing material in Comparative Example 3 of the present invention in the 2-18 GHz frequency band. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0033] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details are not necessarily required to practice the present invention. In other embodiments, well-known structures are not specifically described to avoid obscuring the present invention.

[0034] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. Furthermore, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes only. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] Example 1

[0036] The present invention provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0037] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours;

[0038] (2) Adsorption of MOF: 1.164 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 1.164 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) were dissolved in ethanol, and 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution. 10 mL of an ethanol solution containing 0.382 g of 2-methylimidazole was then added dropwise to the above solution. After the addition was complete, the mixture was allowed to stand for 24 hours and then dried in an oven at 40 °C.

[0039] (3) The dried wood was carbonized in a tubular furnace at 600 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-1) was obtained.

[0040] Electromagnetic parameter test:

[0041] The dielectric constant and magnetic permeability of the material were tested by a coaxial method using a vector network. The test sample was a wood-based porous carbon material powder sample derived from MOF WNC-1 mixed with paraffin in a mass ratio of 2:8 to form a ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm. The test frequency range was 2-18 GHz. According to the transmission line theory, the electromagnetic wave absorption performance of the wave-absorbing material can be calculated by μ r and ε r The reflection loss value of the material was calculated as RL , and the specific expression is as follows:

[0042]

[0043]

[0044] wherein, ε r is the complex dielectric constant, μ r is the complex magnetic permeability, f is the frequency of the electromagnetic wave, d is the thickness of the wave-absorbing material, c is the speed of the electromagnetic wave in free space. In practical applications, it is generally required that RL <-10 dB, indicating that the attenuation loss of the wave-absorbing material to the electromagnetic wave reaches 90%.

[0045] The reflection loss of the MOF-derived wood-based porous carbon wave-absorbing material in this embodiment was calculated according to the electromagnetic parameters, as shown in Figure 1 . The minimum reflection loss value of the porous carbon-based material WNC-1 in this embodiment was RL min =-25.96 dB at a matching thickness of 1.8 mm.

[0046] wherein, the SEM and TEM images of the MOF-derived wood-based porous carbon wave-absorbing material structure are shown in Figure 2 and Figure 3 respectively. It can be clearly observed from the microstructure characterization that the carbonized sample has a porous structure, and a small amount of Co and Ni magnetic particles are loaded on the surface of the porous carbon. Due to the existence of metal ions and carbon-based, gas-solid interfaces in the wood-based porous carbon, the interface polarization effect is stronger, and the multiple reflection / scattering is more obvious, thereby enhancing the attenuation of the material to the electromagnetic wave, and thus the dielectric loss and magnetic loss synergistically improve the wave-absorbing performance of the wood-based porous carbon.

[0047] Example 2

[0048] The present invention provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0049] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours.

[0050] (2) Adsorption of MOF: 1.164 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 1.164 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) were dissolved in ethanol. 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution. 10 mL of an ethanol solution containing 0.382 g of 2-methylimidazole was then added dropwise to the above solution. After the addition was complete, the mixture was allowed to stand for 24 hours and then dried in an oven at 40°C.

[0051] (3) The dried wood was carbonized in a tubular furnace at 900 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-2) was obtained.

[0052] Electromagnetic parameter test:

[0053] The dielectric constant and magnetic permeability of the material were tested by the coaxial method using a vector network. The test sample was a ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm, prepared by mixing the MOF-derived wood-based porous carbon material powder sample labeled WNC-2 with paraffin wax in a ratio of 2:8 (mass ratio). The test frequency band was 2-18 GHz.

[0054] In this embodiment, the reflection loss of the porous carbon-based material is calculated based on the electromagnetic parameters. Figure 4 As shown. The porous carbon-based material WNC-2 in this embodiment reaches the minimum at 16.13 GHz RL min The value is -10.40 dB and the thickness is 1.15 mm.

[0055] Example 3

[0056] The present invention provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0057] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours;

[0058] (2) Adsorption of MOF: 1.746 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 1.746 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) were dissolved in ethanol, 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution, and 10 mL of an ethanol solution containing 0.382 g of 2-methylimidazole was added dropwise to the above solution. After the addition was complete, the mixture was allowed to stand for 24 hours and then dried in an oven at 40 °C.

[0059] (3) The dried wood was carbonized in a tubular furnace at 600 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-3) was obtained.

[0060] Electromagnetic parameter test:

[0061] The dielectric constant and magnetic permeability of the material were tested by the coaxial method using a vector network. The test sample was a circular ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm, prepared by mixing the MOF-derived wood-based porous carbon material powder sample labeled WNC-3 with paraffin wax in a ratio of 2:8 (mass ratio). The test frequency band was 2-18 GHz.

[0062] In this embodiment, the reflection loss of the porous carbon-based material is calculated based on the electromagnetic parameters. Figure 5 As shown. The porous carbon-based material WNC-3 in this embodiment reaches the minimum at 17.29 GHz RL min The value is -13.92 dB and the thickness is 1.4 mm.

[0063] Comparative Example 1

[0064] This comparative example provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0065] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours;

[0066] (2) Adsorption of MOF: 0.582 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and 0.582 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) were dissolved in ethanol, 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution, and 10 mL of ethanol solution containing 0.382 g of 2-methylimidazole was added dropwise to the above solution. After the addition was complete, the solution was allowed to stand for 24 hours and then dried in an oven at 40 °C.

[0067] (3) The dried wood was carbonized in a tubular furnace at 600 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-4) was obtained.

[0068] Electromagnetic parameter test:

[0069] The dielectric constant and magnetic permeability of the material were tested by the coaxial method using a vector network. The test sample was a ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm, prepared by mixing the MOF-derived wood-based porous carbon material powder sample labeled WNC-4 with paraffin wax in a ratio of 2:8 (mass ratio). The test frequency band was 2-18 GHz.

[0070] In this comparative example, the reflection loss of the porous carbon-based material is calculated based on the electromagnetic parameters. Figure 6 The comparative porous carbon-based material WNC-4 reaches its minimum at 8.89 GHz. RL min The value is -3.46 dB, and the thickness is 4.0 mm. It can be seen that compared with Example 1, the wave absorbing performance of the WNC-4 composite material in Comparative Example 1 is significantly reduced.

[0071] Comparative Example 2

[0072] This comparative example provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0073] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours;

[0074] (2) Adsorption of MOF: 2.328 g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was dissolved in ethanol, 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution, and 10 mL of an ethanol solution containing 0.382 g of 2-methylimidazole was added dropwise to the above solution. After the addition was complete, the solution was allowed to stand for 24 hours and then dried in an oven at 40 °C.

[0075] (3) The dried wood was carbonized in a tubular furnace at 600 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-5) was obtained.

[0076] Electromagnetic parameter test:

[0077] The dielectric constant and magnetic permeability of the material were tested by the coaxial method using a vector network. The test sample was a ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm, prepared by mixing the MOF-derived wood-based porous carbon material powder sample labeled WNC-5 with paraffin wax in a ratio of 2:8 (mass ratio). The test frequency band was 2-18 GHz.

[0078] In this comparative example, the reflection loss of the porous carbon-based material is calculated based on the electromagnetic parameters. Figure 7 The comparative porous carbon-based material WNC-5 reaches its minimum at 15.88 GHz. RL min The value is -8.47 dB, and the thickness is 1.1 mm. It can be seen that compared with Example 1, the microwave absorption performance of the WNC-5 composite material in Comparative Example 1 is significantly reduced.

[0079] Comparative Example 3

[0080] This comparative example provides a method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, comprising the following steps:

[0081] (1) Lignin removal: 4.0 g of balsa wood was placed in a round-bottom flask, 260 mL of distilled water was added, the round-bottom flask was placed in a constant temperature water bath, heated to 75 °C, 0.5 mL of acetic acid and 0.6 g of sodium chlorite were added, and after reacting for 1 hour, the same amount of acetic acid and sodium chlorite as in the above step was added. The above steps were repeated three times, and then the filtrate was repeatedly washed with distilled water until the filtrate was neutral, and then dried in an oven at 40 °C for 48 hours;

[0082] (2) Adsorption of MOF: 2.328 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) was dissolved in ethanol, 1.0 g of the wood removed from the lignin in step (1) was placed in the above solution, and 10 mL of an ethanol solution containing 0.382 g of 2-methylimidazole was added dropwise to the above solution. After the addition was complete, the solution was allowed to stand for 24 hours and then dried in an oven at 40 °C.

[0083] (3) The dried wood was carbonized in a tubular furnace at 600 °C under nitrogen protection at a heating rate of 5 °C / min. After cooling, a MOF-derived wood-based porous carbon-based absorbing material (labeled as WNC-6) was obtained.

[0084] Electromagnetic parameter test:

[0085] The dielectric constant and magnetic permeability of the material were tested using a vector network coaxial method. The test sample was a circular ring material with an outer diameter of 7.00 mm and an inner diameter of 3.04 mm, prepared by mixing the MOF-derived wood-based porous carbon material powder sample labeled WNC-6 with paraffin wax in a ratio of 2:8 (mass ratio). The test frequency band was 2-18 GHz.

[0086] In this comparison, the reflection loss of porous carbon-based materials is calculated based on electromagnetic parameters. Figure 8 The comparative example porous carbon-based material WNC-6 reaches its minimum at 16.40 GHz. RL min The value is -6.33 dB, and the thickness is 1.0 mm. It can be seen that compared with Example 1, the microwave absorption performance of the WNC-6 composite material in Comparative Example 1 is significantly reduced.

[0087] Through Examples 1-3 and Comparative Examples 1-3, it can be concluded that the method for preparing the MOF-derived wood porous carbon-based absorbing material in the present invention effectively improves the absorbing effect of the porous material. The present invention can effectively control the microstructure and absorbing performance of the porous material by rationally controlling the ratio between the raw materials and optimizing the preparation process, thereby obtaining a porous carbon-based absorbing material with practical applications.

[0088] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material, characterized in that: The steps include: (1) Lignin removal: Place a certain amount of balsa wood in a round-bottom flask, add distilled water, heat to 65-80°C, add acetic acid and sodium chlorite, add equal amounts of acetic acid and sodium chlorite after the reaction, repeat the addition three times, and then wash and dry; (2) MOF adsorption: A certain amount of cobalt nitrate hexahydrate and nickel nitrate hexahydrate were dissolved in ethanol, and the wood after the lignin removal in step (1) was placed in the ethanol solution, and then the ethanol solution containing 2-methylimidazole was added dropwise. After the addition was completed, the wood was left for 24 hours, and then the wood was dried; the mass ratio of 2-methylimidazole to the lignin removal wood was 5:1 to 1:1; (3) The dried wood is placed in a tubular furnace and calcined and carbonized at a temperature of 600-900 °C under inert gas protection. After cooling, a MOF-derived wood porous carbon-based absorbing material is obtained.

2. The method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material according to claim 1, characterized in that: In the step (2), the mass ratio of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) to nickel nitrate hexahydrate (Ni(NO3)2·6H2O) is 3:10 to 7:

10.

3. The method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material according to claim 1, characterized in that: In the step (3), the carbonization time is 1 to 1.2 h.

4. The method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material according to claim 1, characterized in that: In step (3), the heating rate is 5°C / min.

5. The method for preparing a MOF-derived wood-based porous carbon-based microwave absorbing material according to claim 1, characterized in that: In step (3), nitrogen is used as the inert gas.

6. A MOF-derived wood-based porous carbon-based microwave absorbing material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. Application of the MOF-derived wood-based porous carbon-based absorbing material prepared by the preparation method according to any one of claims 1 to 5 in the field of electromagnetic wave absorption.

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