Preparation method of high-connectivity network structure porous carbon-based composite electromagnetic shielding material

Abstract

The application relates to a high-connection network structure porous carbon-based composite electromagnetic shielding material and a preparation method thereof, and belongs to the technical field of electromagnetic shielding. The composite electromagnetic shielding material is a composite electromagnetic shielding material composed of a porous carbon matrix and a composite reinforcing body of Co3O4 nanoparticles and CNTs, and the Co3O4 nanoparticles and the CNTs are uniformly dispersed on the three-dimensional network structure of the porous carbon. The hydrophilic treated porous carbon is immersed in a cobalt source solution containing CNTs and an aqueous NaOH solution, and subsequent solvothermal reaction can in-situ grow Co3O4 nanoparticles on the three-dimensional network structure of the porous carbon, and the CNTs and the generated Co3O4 nanoparticles are intertwined, so that the composite electromagnetic shielding material is prepared. By simultaneously introducing the Co3O4 nanoparticles and the CNTs into the porous carbon, the electromagnetic shielding performance of the porous carbon can be significantly improved to meet the commercial standard requirements, the preparation process is simple, easy to operate, easy to scale production, and has a good application prospect in the field of electromagnetic shielding materials.

Description

Technical Field

[0001] This invention relates to a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure and its preparation method, belonging to the field of electromagnetic shielding technology. Background Technology

[0002] With the continuous development of society and economy, information technology has also entered an era of rapid development. From the 1G era of mobile communication to the current 5G era of information revolution, various integrated and intelligent electronic and electrical devices have gradually entered fields such as communication, transportation, medical devices, and home appliances. Since its discovery, electromagnetic waves have brought great convenience to people's lives, but they have also brought a large amount of electromagnetic radiation, causing electromagnetic pollution (EMI). Electromagnetic pollution poses a great threat to the environment and human health. Moreover, with the gradual upgrading of electronic devices, the requirements for sensitivity and precision will become increasingly higher, and they will become more sensitive to electromagnetic interference signals. Shielding is one of the most effective methods to resist electromagnetic interference. Excellent conductivity and a perfect conductive network structure are prerequisites for electromagnetic shielding composite materials to achieve high shielding effectiveness. Effective multi-interface reflection absorption and the inherent characteristics of the material itself are important factors in realizing the high performance and controllable shielding performance of electromagnetic shielding composite materials. Therefore, the development of lightweight, efficient, flexible, corrosion-resistant, and low-cost new electromagnetic shielding materials has become an important development direction in the field of electromagnetic shielding materials.

[0003] High-connectivity network-structured porous carbon is a novel type of porous carbon with a three-dimensional structure. It belongs to the category of difficult-to-graphitize carbon materials and, after high-temperature treatment, maintains high flexibility while retaining a certain strength. It possesses advantages such as low density, high strength, good conductivity, corrosion resistance, and ease of processing and molding, making it considered one of the ideal candidates for next-generation electromagnetic shielding materials. However, the electromagnetic shielding performance of porous carbon itself is generally limited, falling short of the performance requirements for electromagnetic shielding materials. Selecting a suitable second-phase material to combine with porous carbon to prepare porous carbon composite materials is the main means to improve the electromagnetic shielding performance of porous carbon.

[0004] The greatest advantage of metals and alloys is their high conductivity, which exhibits excellent electromagnetic wave attenuation capabilities. They are often combined with porous carbon in the form of coatings. However, metals have high density, low corrosion resistance, complex manufacturing processes, and high costs, while metal coatings have poor wear resistance. Transition metal oxides, due to their high magnetic permeability, low cost, good biocompatibility, and high saturation magnetization, have broad application prospects in the field of electromagnetic shielding. Since the electromagnetic shielding performance of materials is determined by dielectric loss and magnetic loss, and porous carbon itself has a low dielectric constant, currently, magnetic materials such as iron oxide and cobalt oxide are mostly used alone as reinforcements. The electromagnetic shielding performance of porous carbon-based corrosion-resistant composite materials does not meet commercial standards, and further improvements are needed to meet commercial application requirements. Summary of the Invention

[0005] To address the shortcomings of current porous carbon-based composite electromagnetic shielding materials, this invention provides a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure and its preparation method. By simultaneously introducing Co3O4 nanoparticles and CNTs into porous carbon, the electromagnetic shielding performance can be significantly improved to meet commercial standards. During the preparation process, by hydrophilically treating the porous carbon and with the assistance of CNTs, Co3O4 nanoparticles can grow in situ on the porous carbon network structure, and the continuous growth of nanoparticles can be inhibited. Ultimately, the Co3O4 nanoparticles and CNTs are intertwined and uniformly dispersed.

[0006] The objective of this invention is achieved through the following technical solutions.

[0007] A porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure is a composite electromagnetic shielding material composed of a porous carbon matrix and a composite reinforcement of Co3O4 nanoparticles and CNTs, wherein the Co3O4 nanoparticles and CNTs are uniformly dispersed on the three-dimensional network structure of the porous carbon.

[0008] Furthermore, Co3O4 nanoparticles and CNTs are formed by in-situ growth of Co3O4 nanoparticles on the three-dimensional network structure of porous carbon using a cobalt source solution containing CNTs. The generated Co3O4 nanoparticles and CNTs are intertwined to achieve a uniform distribution of both on the three-dimensional network structure of porous carbon.

[0009] The cobalt source solution containing CNTs is prepared from Co(NO3)2·6H2O, CNTs and ethanol.

[0010] Furthermore, the concentration of Co(NO3)2·6H2O is 0.1–0.3 mol / L, and the concentration of CNTs is 0.1–0.5 mg / mL. At this time, the volume ratio of the cobalt source solution containing CNTs to the porous carbon is (6–3):1.

[0011] A method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure includes the following steps:

[0012] (1) Hydrophilic treatment of porous carbon;

[0013] (2) The hydrophilically treated porous carbon is immersed in a cobalt source solution containing CNTs, and NaOH aqueous solution is added at the same time. The mixture is stirred evenly to form a reaction solution.

[0014] (3) The reaction solution is transferred to the reaction vessel for solvothermal reaction, so that the cobalt source grows in situ on the three-dimensional network structure of porous carbon to form Co3O4 nanoparticles. At the same time, CNTs are entangled with the generated Co3O4 nanoparticles, thereby achieving a uniform distribution of Co3O4 nanoparticles and CNTs on the three-dimensional network structure of porous carbon.

[0015] (4) After the solvothermal reaction is completed, the reaction products are collected, washed and dried to obtain Co3O4 nanoparticles / CNTs / porous carbon composite material, which is the porous carbon-based composite electromagnetic shielding material with high interconnection network structure described in this invention.

[0016] The porous carbon in step (1) is preferably prepared by melamine foam carbonization;

[0017] The carbonization process conditions are as follows: under a nitrogen or inert gas protective atmosphere, the temperature is first raised to 350-450℃ and held for 1-2 hours, then raised to 700-1000℃ and held for 1-2 hours, and then cooled down. The heating rate and cooling rate are both 5-15℃ / min.

[0018] The preferred method is to use nitric acid solution to perform hydrophilic treatment on porous carbon. The specific operation is as follows: the porous carbon is placed in a nitric acid solution with a concentration of 2-3 mol / L, heated to 100-130℃ and kept at this temperature for 1-3 hours. After that, the porous carbon is taken out, washed and dried, thus completing the hydrophilic treatment of the porous carbon.

[0019] In step (2), the cobalt source solution containing CNTs is prepared from Co(NO3)2·6H2O, CNTs, and ethanol. The concentration of Co(NO3)2·6H2O is preferably 0.1–0.3 mol / L, and the concentration of CNTs is preferably 0.1–0.5 mg / mL. Correspondingly, the volume ratio of the cobalt source solution containing CNTs to the hydrophilically treated porous carbon is preferably (6–3):1, the volume ratio of the cobalt source solution containing CNTs to the NaOH aqueous solution is (12–13:1), and the concentration of the NaOH aqueous solution is 0.1–0.3 mol / L.

[0020] In step (3), the temperature of the solvothermal reaction is 160-200℃ and the time is 8-18h.

[0021] Beneficial effects:

[0022] (1) In this invention, highly conductive CNTs and transition metal oxide Co3O4 magnetic nanoparticles are selected as composite reinforcing materials, and flexible porous carbon is used as the matrix. By improving the dielectric loss and magnetic loss of the composite material, the electromagnetic shielding performance of the porous carbon-based composite material is effectively enhanced, and a flexible lightweight electromagnetic shielding composite material with excellent electromagnetic shielding performance is obtained.

[0023] (2) During the solvothermal process, porous carbon utilizes its strong adsorption force to adsorb a large amount of Co. 2+ These Co 2+ The CNTs become the nuclei for the subsequent Co3O4 formation, and the crystals continue to grow in situ to generate Co3O4 nanoparticles. The addition of CNTs can inhibit the continuous growth of Co3O4 nanoparticles and effectively inhibit the agglomeration of smaller Co3O4 nanoparticles, thereby achieving uniform attachment of Co3O4 nanoparticles to the porous carbon network structure.

[0024] (3) Porous carbon itself is lightweight, bulky, and extremely hydrophobic. To ensure that Co3O4 nanoparticles can adhere and grow well, it needs to be hydrophilicated so that it can be fully immersed in the reaction solution. If the hydrophilicity is insufficient, the porous carbon will float on the reaction solution and will not be able to form a Co3O4 nanoparticle / CNTs / porous carbon composite material. If the hydrophilicity is excessive, the three-dimensional structure of the porous carbon will be corroded, destroying its structural integrity.

[0025] (4) Since porous carbon has a very high porosity, it must be mixed with a reaction solution of a certain concentration in a suitable volume ratio. If the volume ratio is too large, the wetting will be incomplete, while if it is too small, the introduction of NaOH solution will increase the impact on the subsequent formation of Co3O4 nanoparticles and reduce the electromagnetic shielding performance of the Co3O4 nanoparticle / CNTs / porous carbon composite material.

[0026] (5) The method described in this invention is simple, easy to operate, and easy to scale up for production. Moreover, the electromagnetic shielding performance of the prepared composite material meets the commercial standard requirements and has a good application prospect in the field of electromagnetic shielding materials. Attached Figure Description

[0027] Figure 1 The image shows a comparison of the X-ray diffraction (XRD) spectra of the Co3O4 nanoparticle / CNTs / porous carbon composite material prepared in Example 1 and the Co3O4 nanoparticle / CNTs / porous carbon composite material prepared in Example 2.

[0028] Figure 2 The image shows a scanning electron microscope (SEM) image of the porous carbon prepared in Example 1.

[0029] Figure 3 yes Figure 2 A magnified view of the marked area.

[0030] Figure 4 This is a scanning electron microscope image of the Co3O4 nanoparticle / CNTs / porous carbon composite material prepared in Example 1.

[0031] Figure 5 yes Figure 4 A magnified view of the marked area.

[0032] Figure 6 The graph shows the electromagnetic shielding performance of the Co3O4 nanoparticle / CNTs / porous carbon composite material and porous carbon prepared in Example 1.

[0033] Figure 7 The images show SEM images of different regions of the Co3O4 nanoparticle / porous carbon composite material prepared in Comparative Example 1 at different magnifications; the left image is a low-magnification SEM image, and the right image is a high-magnification SEM image.

[0034] Figure 8 The images show SEM images of different regions of the Co3O4 nanoparticle / porous carbon composite material prepared in Comparative Example 2 at different magnifications; the left image is a low-magnification SEM image, and the right image is a high-magnification SEM image. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are obtainable from publicly available commercial sources.

[0036] Example 1

[0037] (1) First, the melamine foam was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min each. Then, it was placed in a 60℃ oven to dry for 12 h. Then, it was transferred to a tube furnace filled with N2 for carbonization. First, it was heated to 400℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was heated to 1000℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was cooled at a cooling rate of 5℃ / min to obtain porous carbon.

[0038] (2) Add 72 mL of deionized water to 9 mL of 68% nitric acid and mix well to form a nitric acid solution with a concentration of 2.5 mol / L. Immerse the porous carbon prepared in step (1) into the nitric acid solution prepared in step (2), transfer it into a polytetrafluoroethylene liner, place it in a reaction vessel, heat it to 120°C in an oven, keep it warm for 1 hour, take out the porous carbon and wash it repeatedly with deionized water until it is neutral, and then place it in a 60°C oven to dry for 12 hours to complete the hydrophilic treatment of the porous carbon.

[0039] (3) Mix 1.1646g Co(NO3)2·6H2O, 37mL anhydrous ethanol and 8mg CNTs, and sonicate for 1h to obtain a cobalt source solution containing CNTs; immerse the hydrophilically treated porous carbon in the cobalt source solution containing CNTs with a volume ratio of 1:4, and add 3mL of 0.2mol / L NaOH aqueous solution, and then sonicate for 30min to obtain a reaction solution;

[0040] (4) Transfer the reaction solution prepared in step (3) into the polytetrafluoroethylene liner, place it in the reaction vessel and carry out a solvothermal reaction in a vacuum drying oven at a reaction temperature of 180°C for 12 hours.

[0041] (5) After the solvothermal reaction is completed, the reaction product is collected and repeatedly washed with ethanol. Then it is placed in a 60℃ oven and dried for 12h to obtain a porous carbon-based composite electromagnetic shielding material with a high interconnection network structure, which is abbreviated as Co3O4 nanoparticles / CNTs / porous carbon composite material.

[0042] Phase analysis was performed on the composite material prepared in step (5). Figure 1 The XRD pattern shows that the composite material contains Co3O4.

[0043] The morphology of the porous carbon prepared in step (1) was characterized, combined with... Figure 2 and Figure 3 It can be seen that porous carbon has a complete pore structure, a clear ligament structure connecting the pores, and a high porosity.

[0044] The morphology of the composite material prepared in step (5) was characterized. Figure 4 and Figure 5 As can be seen, Co3O4 nanoparticles showed no obvious aggregation and successfully grew on the surface of porous carbon ligaments. At the same time, CNTs and Co3O4 nanoparticles were intertwined and evenly dispersed.

[0045] Electromagnetic shielding performance tests were performed on the composite material prepared in step (5) and the porous carbon prepared in step (1). Figure 6 Test results show that the total shielding effectiveness of the composite material can reach up to 27dB in the 8.2-12.4GHz band, which meets the commercial standard requirements (the total shielding effectiveness should not be less than 20dB) and is significantly better than the shielding performance of porous carbon.

[0046] Example 2

[0047] (1) First, the melamine foam was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min each. Then, it was placed in a 60℃ oven to dry for 12 h. Then, it was transferred to a tube furnace filled with N2 for carbonization. First, it was heated to 400℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was heated to 1000℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was cooled at a cooling rate of 5℃ / min to obtain porous carbon.

[0048] (2) Add 144 mL of deionized water to 18 mL of 68% nitric acid and mix well to form a nitric acid solution with a concentration of 2.5 mol / L. Immerse the porous carbon prepared in step (1) into the nitric acid solution prepared in step (2), transfer it into a polytetrafluoroethylene liner, place it in a reaction vessel, heat it to 100°C in an oven, keep it warm for 1 hour, take out the porous carbon and wash it repeatedly with deionized water until it is neutral, and then place it in a 60°C oven to dry for 12 hours to complete the hydrophilic treatment of the porous carbon.

[0049] (3) Mix 3.4938g Co(NO3)2·6H2O, 111mL anhydrous ethanol and 12mg CNTs, and sonicate for 1h to obtain a cobalt source solution containing CNTs; immerse the hydrophilically treated porous carbon in the cobalt source solution containing CNTs with a volume ratio of 1:6, add 9mL of 0.3mol / L NaOH aqueous solution, and then sonicate for 30min to obtain a reaction solution;

[0050] (4) Transfer the reaction solution prepared in step (3) into the polytetrafluoroethylene liner, place it in the reaction vessel and carry out a solvothermal reaction in a vacuum drying oven at a reaction temperature of 180°C for 12 hours.

[0051] (5) After the solvothermal reaction is completed, the reaction product is collected and repeatedly washed with ethanol. Then it is placed in a 60℃ oven and dried for 12h to obtain a porous carbon-based composite electromagnetic shielding material with a high interconnection network structure, which is abbreviated as Co3O4 nanoparticles / CNTs / porous carbon composite material.

[0052] Phase analysis was performed on the composite material prepared in step (5). Figure 1 The XRD pattern shows that the composite material contains Co3O4.

[0053] The morphology of the composite material prepared in step (5) was characterized. According to the characterization results, the Co3O4 nanoparticles showed no obvious agglomeration and were successfully grown on the surface of the porous carbon ligament. At the same time, the CNTs and Co3O4 nanoparticles were intertwined and evenly dispersed.

[0054] The electromagnetic shielding performance of the composite material prepared in step (5) was tested. In the 8.2-12.4 GHz band, the total shielding effectiveness was measured to be up to 23 dB, which meets the commercial standard requirements.

[0055] Comparative Example 1

[0056] (1) First, the melamine foam was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min each. Then, it was placed in a 60℃ oven to dry for 12 h. Then, it was transferred to a tube furnace filled with N2 for carbonization. First, it was heated to 400℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was heated to 1000℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was cooled at a cooling rate of 5℃ / min to obtain porous carbon.

[0057] (2) Add 72 mL of deionized water to 9 mL of 68% nitric acid and mix well to form a nitric acid solution with a concentration of 2.5 mol / L. Immerse the porous carbon prepared in step (1) into the nitric acid solution prepared in step (2), transfer it into a polytetrafluoroethylene liner, place it in a reaction vessel, heat it to 120°C in an oven, keep it warm for 1 hour, take out the porous carbon and wash it repeatedly with deionized water until it is neutral, and then place it in a 60°C oven to dry for 12 hours to complete the hydrophilic treatment of the porous carbon.

[0058] (3) Mix 1.1646g Co(NO3)2·6H2O and 37mL anhydrous ethanol, and sonicate for 1h to obtain a uniform cobalt source solution; immerse the hydrophilic treated porous carbon in the cobalt source solution with a volume ratio of 1:4, and add 3mL of 0.2mol / L NaOH aqueous solution, and then sonicate for 30min to obtain a reaction solution;

[0059] (4) Transfer the reaction solution prepared in step (3) into the polytetrafluoroethylene inner liner, place it in the reaction vessel and carry out a solvothermal reaction in a vacuum drying oven at a reaction temperature of 180°C for 12 hours.

[0060] (5) After the solvothermal reaction is completed, the reaction product is collected and repeatedly washed with ethanol. Then it is placed in a 60℃ oven and dried for 12h to obtain a porous carbon-based composite electromagnetic shielding material with a high interconnection network structure, which is abbreviated as Co3O4 nanoparticle / porous carbon composite material.

[0061] The morphology of the composite material prepared in step (5) was characterized. Figure 7 As can be seen, without the addition of CNTs, the Co3O4 nanoparticles grown in situ on the porous carbon are interconnected to form a continuous coating layer that uniformly wraps the porous carbon network structure, rather than being uniformly dispersed as independent Co3O4 nanoparticles on the porous carbon network structure.

[0062] Electromagnetic shielding performance of the composite material prepared in step (5) was tested. In the 8.2-12.4 GHz band, the total shielding effectiveness was measured to be up to 19 dB, which did not meet the commercial standard requirements.

[0063] Comparative Example 2

[0064] (1) First, the melamine foam was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min each. Then, it was placed in a 60℃ oven to dry for 12 h. Then, it was transferred to a tube furnace filled with N2 for carbonization. First, it was heated to 400℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was heated to 1000℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was cooled at a cooling rate of 5℃ / min to obtain porous carbon.

[0065] (2) Mix 1.1646g Co(NO3)2·6H2O and 37mL anhydrous ethanol, and sonicate for 1h to obtain a uniform cobalt source solution; immerse the porous carbon prepared in step (1) into the cobalt source solution with a volume ratio of 1:4, and add 3mL of 0.2mol / L NaOH aqueous solution, and then sonicate for 30min to obtain a reaction solution;

[0066] (3) Transfer the reaction solution prepared in step (2) into the polytetrafluoroethylene inner liner, place it in the reaction vessel and carry out a solvothermal reaction in a vacuum drying oven at a reaction temperature of 180°C for 12 hours.

[0067] (4) After the solvothermal reaction is completed, the reaction product is collected and repeatedly washed with ethanol. Then it is placed in a 60℃ oven and dried for 12h to obtain a porous carbon-based composite electromagnetic shielding material with a high interconnection network structure, which is abbreviated as Co3O4 nanoparticle / porous carbon composite material.

[0068] The morphology of the composite material prepared in step (4) was characterized, from Figure 8 As can be seen, when porous carbon is not hydrophilically treated, the Co3O4 nanoparticles generated by the subsequent solvothermal reaction cannot be effectively attached to the network structure of porous carbon. At this time, the amount of Co3O4 nanoparticles loaded on the porous carbon network structure is extremely small, and the generated Co3O4 is an irregularly shaped nanoparticle (such as sheet-like, needle-like, and irregular spherical shapes).

[0069] Comparative Example 3

[0070] (1) First, the melamine foam was ultrasonically cleaned with deionized water and anhydrous ethanol for 30 min each. Then, it was placed in a 60℃ oven to dry for 12 h. Then, it was transferred to a tube furnace filled with N2 for carbonization. First, it was heated to 400℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was heated to 1000℃ at a heating rate of 5℃ / min and held for 1 h. Then, it was cooled at a cooling rate of 5℃ / min to obtain porous carbon.

[0071] (2) Add 72 mL of deionized water to 9 mL of 68% nitric acid and mix well to form a nitric acid solution with a concentration of 2.5 mol / L. Immerse the porous carbon prepared in step (1) into the nitric acid solution prepared in step (2), transfer it into a polytetrafluoroethylene liner, place it in a reaction vessel, heat it to 120°C in an oven, keep it warm for 1 hour, take out the porous carbon and wash it repeatedly with deionized water until it is neutral, and then place it in a 60°C oven to dry for 12 hours to complete the hydrophilic treatment of the porous carbon.

[0072] (3) Mix 1.1646g Co(NO3)2·6H2O and 37mL anhydrous ethanol, and sonicate for 1h to obtain a uniform cobalt source solution; immerse the hydrophilic treated porous carbon in the cobalt source solution with a volume ratio of 1:1, and add 3mL of 0.2mol / L NaOH aqueous solution, and then sonicate for 30min to obtain a reaction solution;

[0073] (4) Transfer the reaction solution prepared in step (3) into the polytetrafluoroethylene liner, place it in the reaction vessel and carry out a solvothermal reaction in a vacuum drying oven at a reaction temperature of 180°C for 12 hours.

[0074] (5) After the solvothermal reaction is completed, the reaction product is collected and repeatedly washed with ethanol. Then it is placed in a 60℃ oven and dried for 12h to obtain a porous carbon-based composite electromagnetic shielding material with a high interconnection network structure, which is abbreviated as Co3O4 nanoparticle / porous carbon composite material.

[0075] The morphology of the composite material prepared in step (5) was characterized. According to the characterization results, the wettability was incomplete due to the large volume ratio of the hydrophilic porous carbon to the cobalt source solution. As a result, the Co3O4 nanoparticles generated by the subsequent solvothermal reaction could only be locally loaded on the network structure of the porous carbon, and could not achieve uniform loading on the network structure of the porous carbon.

[0076] In summary, the above are merely preferred embodiments of the present invention and are 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 within the scope of protection of the present invention.

Claims

1. A method for preparing a porous carbon-based composite electromagnetic shielding material with a highly interconnected network structure, characterized in that: The composite electromagnetic shielding material is a composite electromagnetic shielding material composed of a porous carbon matrix and a composite reinforcement of Co3O4 nanoparticles and CNTs, and the Co3O4 nanoparticles and CNTs are uniformly dispersed on the three-dimensional network structure of the porous carbon. The preparation method includes the following steps: (1) Hydrophilic treatment of porous carbon; (2) The hydrophilically treated porous carbon is immersed in a cobalt source solution containing CNTs, and NaOH aqueous solution is added at the same time. The mixture is stirred evenly to form a reaction solution. (3) The reaction solution is transferred to the reaction vessel for solvothermal reaction, so that the cobalt source grows in situ on the three-dimensional network structure of porous carbon to form Co3O4 nanoparticles. At the same time, CNTs are entangled with the generated Co3O4 nanoparticles, thereby achieving a uniform distribution of Co3O4 nanoparticles and CNTs on the three-dimensional network structure of porous carbon. (4) After the solvothermal reaction is completed, the reaction products are collected, washed and dried to obtain Co3O4 nanoparticles / CNTs / porous carbon composite material, which is a porous carbon-based electromagnetic shielding material with a high interconnection network structure. In step (2), the cobalt source solution containing CNTs is prepared from Co(NO3)2·6H2O, CNTs and ethanol.

2. The method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure according to claim 1, characterized in that: The porous carbon in step (1) is prepared by melamine foam carbonization; The carbonization process conditions are as follows: Under a nitrogen or inert gas protective atmosphere, the temperature is first raised to 350~450 ℃ and held for 1~2 h, then the temperature is raised to 700~1000 ℃ and held for 1~2 h, and then cooled down. The heating rate and cooling rate are both 5~15 ℃ / min.

3. The method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure according to claim 1, characterized in that: In step (1), the porous carbon is hydrophilically treated with nitric acid solution. The specific operation is as follows: the porous carbon is placed in a nitric acid solution with a concentration of 2~3 mol / L, heated to 100~130 ℃ and kept at the temperature for 1~3 h. After that, the porous carbon is taken out, washed and dried, thus completing the hydrophilic treatment of the porous carbon.

4. The method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure according to claim 1, characterized in that: In step (2), the concentration of Co(NO3)2·6H2O in the cobalt source solution containing CNTs is 0.1~0.3 mol / L, and the concentration of CNTs is 0.1~0.5 mg / mL.

5. The method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure according to claim 4, characterized in that: In step (2), the volume ratio of the cobalt source solution containing CNTs to the hydrophilically treated porous carbon is (6~3):1, the volume ratio of the cobalt source solution containing CNTs to the NaOH aqueous solution is (12~13:1), and the concentration of the NaOH aqueous solution is 0.1~0.3 mol / L.

6. The method for preparing a porous carbon-based composite electromagnetic shielding material with a high interconnectivity network structure according to claim 1, characterized in that: In step (3), the temperature of the solvothermal reaction is 160~200 ℃ and the time is 8~18 h.

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