Magnetic metal composite aerogel and preparation method and application thereof

Abstract

The application provides a magnetic metal composite aerogel as well as a preparation method and application thereof, relates to a multi-component composite material in the field of electromagnetic functional materials. The application utilizes a hydrothermal method to synthesize cobalt-based metal-organic frameworks (Co-MOFs), and through accurate control of a heat treatment process of the Co-MOFs, such as carbonization temperature, atmosphere and time, etc., finally obtains Co / C / MXene composite aerogels with different performances. The prepared aerogel composite material realizes organic combination of magnetic metals, graphene and MXene materials, plays a synergistic effect of magnetic loss, dielectric loss and electric conduction loss, has excellent electromagnetic shielding performance, and has important practical significance in fields of coping with electromagnetic radiation and electromagnetic pollution protection, etc.

Description

Technical Field

[0001] This invention relates to multi-component composite materials in the field of electromagnetic functional materials, specifically to a magnetic metal composite aerogel, its preparation method, and its application. Background Technology

[0002] The development of electromagnetic materials plays a crucial role in modern society, forming the foundation of modern electronics, communications, and energy. From mobile phones and computers to various communication devices, all rely on the performance of electromagnetic materials; the conductivity, dielectric constant, and magnetic properties of these materials directly determine the performance and functionality of the devices. With the increasing prominence of global energy issues, energy conservation and emission reduction have become important tasks for governments and enterprises worldwide. Developing low-power, high-efficiency electromagnetic materials can reduce the energy consumption of electronic devices, extend battery life, and decrease energy consumption, thereby alleviating environmental pressure and achieving sustainable development. Furthermore, the development of electromagnetic materials is also crucial for enhancing a nation's technological strength and defense capabilities. Modern military equipment has a huge demand for electromagnetic materials; from radar systems to communication equipment, high-performance and reliable electromagnetic materials are essential. The development of electromagnetic materials is not only significant for promoting the development of the electronics, communications, and energy industries, but also for energy conservation and emission reduction, ensuring national security, and promoting technological innovation. Therefore, increasing investment in electromagnetic material research and development and promoting its technological advancement is of great importance for promoting social progress and sustainable development.

[0003] Aerogel materials possess unique advantages in the field of electromagnetic materials, exhibiting extremely low density and a highly open porous structure. A porosity exceeding 90% results in aerogel materials displaying extremely low dielectric constant and permeability during electromagnetic wave propagation. This characteristic enables aerogel materials to demonstrate excellent performance in high-frequency electromagnetic wave fields such as microwaves and radio frequencies, effectively reducing electromagnetic wave reflection and absorption and improving transmission efficiency. Aerogel materials also possess excellent thermal and chemical stability. This allows them to maintain good electromagnetic properties even under harsh environments such as high temperatures and acid / alkali conditions, resisting degradation or damage. This stability makes aerogel materials highly promising for applications in high-temperature environments such as aerospace and automotive electronics. Aerogel materials also offer good tunability and customizability. By adjusting parameters such as composition, pore structure, and morphology, precise control over their electromagnetic properties can be achieved to meet the needs of different application scenarios. This tunability makes aerogel materials promising for applications in electromagnetic wave shielding, microwave absorption, and antenna design. Furthermore, aerogel materials also offer advantages such as lightweight, environmental friendliness, and ease of processing. Due to their low density and high porosity, aerogel materials have extremely low weight, which can reduce the overall weight of electronic devices and improve their portability and mobility. At the same time, aerogel materials typically use inorganic aerogels as the matrix, exhibiting good weather resistance and environmental adaptability, and are not easily affected by moisture, aging, or corrosion, thus contributing to improved device lifespan and reliability.

[0004] MXenes are a class of two-dimensional materials, typically composed of transition metal carbides. Their structural basis consists of hexagonal layers formed by transition metals and carbon or nitrogen. Due to this unique composition, MXenes possess excellent electromagnetic and mechanical properties, along with extremely large specific surface area activity and exceptional plasticity and flexibility. Therefore, they are widely used in the manufacture of conductive inks, flexible electrodes, and transparent conductive films. Summary of the Invention

[0005] This invention is based on the above background technology and aims to provide a magnetic metal composite aerogel, its preparation method and application.

[0006] This invention provides a method for preparing magnetic metal composite aerogel, characterized by the following steps: S10, dissolving cobalt salt and 2,5-dihydroxyterephthalic acid in a solvent and carrying out a hydrothermal reaction to obtain a cobalt metal-organic framework; S20, carbonizing the cobalt metal-organic framework to obtain a Co / C aerogel; S30, immersing the Co / C aerogel in an MXene solution to obtain a magnetic metal composite aerogel.

[0007] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: in step S10, the cobalt salt includes cobalt acetate tetrahydrate and / or cobalt chloride tetrahydrate, and the solvent includes any one or more of anhydrous ethanol, methanol or deionized water.

[0008] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: wherein step S10 includes the following sub-steps: S11, mixing cobalt salt solution with 2,5-dihydroxyterephthalic acid solution and stirring to obtain a reaction solution; S12, adding water to the reaction solution and carrying out a hydrothermal reaction to prepare a solution of cobalt metal organic framework.

[0009] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: In step S11, the concentration of cobalt salt in the cobalt salt solution is 20-40 mg / mL, the concentration of 2,5-dihydroxyterephthalic acid in the 2,5-dihydroxyterephthalic acid solution is 2-10 mg / mL, the volume ratio of cobalt salt solution to 2,5-dihydroxyterephthalic acid solution is (1-8):(1-4), and the stirring time is 2 h; In step S12, the volume ratio of water added to reaction solution is (1-3):(1-9), and the hydrothermal reaction conditions are: heating to 50-180°C at a heating rate of 1°C / min-10°C / min and then holding at that temperature for 12-24 h.

[0010] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: step S20 includes the following sub-steps: S21, preparing a Co / C composite solution by mixing a cobalt metal-organic framework and graphene in a solvent; S22, freezing-drying the Co / C composite solution and heating it under an inert atmosphere to obtain a Co / C aerogel.

[0011] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: wherein, the mass of the cobalt metal-organic framework in step S21 is denoted as m1, the mass of graphene is denoted as m2, m1:m2=1:(4~10), and in step S22, the inert atmosphere is argon gas, and the heating method is: heating to 500℃~900℃ at a heating rate of 2℃ / min~10℃ / min and then holding at that temperature for 60min~180min.

[0012] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following feature: in step S21, chitosan solution and ethanol are added.

[0013] The method for preparing magnetic metal composite aerogel provided by the present invention may also have the following features: the immersion method in step S30 is as follows: MXene solution is uniformly added dropwise to the surface of Co / C aerogel until MXene solution precipitates from the bottom of Co / C aerogel, and Co / C aerogel is transformed into Co / C / MXene composite aerogel, that is, magnetic metal composite aerogel. The mass of MXene in the MXene solution in step S30 is recorded as m3, and m1:m3 = 1:(0.01~0.2).

[0014] The present invention also provides a magnetic metal composite aerogel, which is characterized by being prepared by any of the aforementioned methods for preparing magnetic metal composite aerogels.

[0015] The present invention also provides an application of magnetic metal composite aerogel in electromagnetic shielding, characterized in that the electromagnetic shielding performance of the magnetic metal composite aerogel is 20-50 dB.

[0016] The role and effect of invention

[0017] This invention utilizes a hydrothermal method to synthesize cobalt-based metal-organic frameworks (Co-MOFs). Through precise control of the heat treatment process of Co-MOFs, such as carbonization temperature, atmosphere, and time, Co / C / MXene composite aerogels with different properties are finally obtained. The prepared aerogel composites achieve an organic combination of magnetic metal, graphene, and MXene materials, exerting a synergistic effect of magnetic loss, dielectric loss, and conductivity loss, and exhibiting excellent electromagnetic shielding performance. This has important practical significance in the fields of electromagnetic radiation and electromagnetic pollution protection.

[0018] This invention utilizes the porous and lightweight characteristics of aerogel materials, combined with MXene materials possessing excellent electromagnetic properties, to prepare a composite aerogel with certain mechanical properties, lightweight yet high strength, and stable characteristics. Given the current market demand, this material has broad development prospects.

[0019] The preparation method of the magnetic metal composite aerogel of the present invention is simple, green, environmentally friendly and the parameters are controllable. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for preparing a magnetic metal composite aerogel according to an embodiment of the present invention.

[0021] Figure 2 These are the XRD patterns of sample 1, sample 2, sample 3, and the control sample in the test examples of this invention;

[0022] Figure 3These are the SEM images of sample 1, sample 2, sample 3, and the control sample in the test examples of this invention;

[0023] Figure 4 These are the EMI performance curves of samples 1, 2, 3 and the control sample in the test examples of this invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate a magnetic metal composite aerogel of this invention, its preparation method and application.

[0025] <Example>

[0026] Figure 1 This is a flowchart illustrating a method for preparing a magnetic metal composite aerogel according to an embodiment of the present invention.

[0027] like Figure 1 As shown, this embodiment provides a method for preparing magnetic metal composite aerogel, including the following steps:

[0028] S10, Preparation of cobalt metal-organic frameworks, including the following sub-steps:

[0029] S11, prepare a 100 mL methanol solution of 1 g cobalt salt and a 50 mL methanol solution of 2 g 2,5-dihydroxyterephthalic acid, mix and stir continuously for 2 h to allow the reaction to proceed fully, and obtain the reaction solution;

[0030] S12, after adding 50 mL of water to the reaction solution, a hydrothermal reaction was carried out at 180 °C for 12 h to prepare a solution of cobalt metal-organic framework.

[0031] S20, the cobalt metal-organic framework is carbonized to obtain Co / C aerogel, including the following sub-steps:

[0032] S21, after concentrating and adjusting the volume of the cobalt metal-organic framework solution from step S12, mix it with the graphene solution, add 6.25 mL of chitosan solution with a concentration of 40 mg / mL to help with subsequent aerogel formation, add 1 mL of ethanol to enhance surface tension, and prepare 20 mL of Co / C composite material solution.

[0033] S22, the Co / C composite solution was stirred for 3 hours to ensure uniformity, frozen for 12 hours, freeze-dried for 24 hours, and then kept at T℃ for 2 hours under Ar atmosphere to obtain Co / C aerogel.

[0034] S30, Preparation of magnetic metal composite aerogel, including the following sub-steps:

[0035] S31, MXene solution was prepared by etching Ti3AlC2 with HCl / LiF mixed solution and its concentration was controlled to be x3 mg / mL;

[0036] S32, 5 mL of MXene solution was uniformly added dropwise to the surface of Co / C aerogel until the MXene solution precipitated from the bottom of Co / C aerogel. The product was then vacuum dried for 12 h, and the Co / C aerogel was transformed into Co / C / MXene composite aerogel, thus obtaining magnetic metal composite aerogel.

[0037] This embodiment also provides a magnetic metal composite aerogel, which is prepared by the method for preparing magnetic metal composite aerogel provided in this embodiment.

[0038] In this embodiment, by controlling the specific parameters in the preparation process, three magnetic metal composite aerogels were obtained, which were denoted as Sample 1, Sample 2 and Sample 3, respectively. The different specific parameters in the preparation process are shown in Table 1.

[0039] Table 1 (Specific parameters during the preparation of Sample 1, Sample 2, and Sample 3)

[0040]

[0041] <Comparative Example>

[0042] This comparative example uses composite aerogels prepared as samples 1, 2, and 3 of the embodiment for comparison. The composite aerogel used as comparison is referred to as the control sample. The preparation method of the control sample includes the following steps:

[0043] S01, prepare a 2.11 wt% graphene solution and a 40 mg / mL chitosan solution.

[0044] S02, using 12.75 mL of graphene solution as a substrate, prepared CS / GO aerogel with a volume of 20 mL. 6.25 mL of chitosan solution was added to help with subsequent aerogel formation, and 1 mL of ethanol was added to enhance surface tension.

[0045] S03, stir for 3 hours to ensure the solution is homogeneous, freeze for 12 hours, and freeze dry for 24 hours.

[0046] S04 was heated at 800℃ for 2 hours in an Ar atmosphere to obtain a control sample.

[0047] <Test Example>

[0048] This test case uses X-ray diffraction (XRD). The crystal structures of Sample 1, Sample 2, Sample 3 and the control sample were determined.

[0049] Figure 2 These are the XRD patterns of sample 1, sample 2, sample 3, and control sample in the test examples of this invention.

[0050] like Figure 2 As shown, samples 1, 2, and 3 have similar crystal structures. The diffraction peak at 44.5° was identified as the (111) crystal plane of metallic Co (JCPDS: 15-0806), confirming the presence of magnetic Co metal. Furthermore, a broad peak was observed near 2θ = 26°, which is correlated with the (002) crystal plane of graphitized carbon (JCPDS No. 75-1621). Moreover, the intensity of the graphite peak increases from sample 1 to sample 2 and decreases from sample 2 to sample 3, indicating that the crystallinity of graphitized carbon peaks with increasing Co content. The results demonstrate that, in an inert atmosphere, magnetic metallic Co particles grow through reduction and nucleation by metal ions. Cobalt metal has a certain catalytic effect on the carbonization of organic ligands; the organic ligands are pyrolyzed and carbonized, and each carbon atom produced interacts with the sp atoms in the carbon structure. 2 The three adjacent carbon atoms in the hybrid orbitals are bonded. XRD patterns show that the control sample does not contain the MXene phase component, while the magnetic metal composite aerogel of Co / C / MXene was successfully prepared in the examples.

[0051] This test case also used scanning electron microscopy to observe the morphology of sample 1, sample 2, sample 3 and the control sample and performed energy dispersive spectroscopy.

[0052] Figure 3 These are the SEM images of sample 1, sample 2, sample 3, and control sample in the test examples of this invention.

[0053] like Figure 3 As shown, the SEM images of samples 1, 2, and 3 are magnified to 200×, and all three samples exhibit a layered porous structure. Despite using the same composition and different component mass ratios, the samples show relatively similar morphological characteristics. After 12 hours of freezing, ice crystals with a certain orientation regularity formed in the graphene system solution, such as... Figure 3 After 24 hours of freeze-drying, the ice crystals sublimated to form pores. The addition of MXene solution resulted in wrinkles on the surface of the layered structure of the sample. After adding the Co-NT complex, all three samples and the control sample maintained their layered porous geometry, with no significant change in microstructure. However, the pore size varied with different Co-NT complex contents; Figure b shows a slight reduction in pore size. SEM images indicate that porous aerogels were successfully prepared in the examples. The microstructure of the control sample was similar to that of the example samples, exhibiting a layered porous structure with wrinkles, but its pore size was relatively larger.

[0054] Depend on Figure 2 XRD patterns and Figure 3 The SEM images show that the example successfully prepared a porous aerogel of Co / C / MXene composite material, namely a magnetic metal composite aerogel.

[0055] In this test example, Sample 1, Sample 2, Sample 3, and the control sample were cut into square specimens with a length of 2.2 cm, a width of 1.1 cm, and a thickness of 0.4 cm, respectively. Then, the electromagnetic parameters were measured using a vector network analyzer in the frequency range of 8.2 GHz to 12.4 GHz, thereby providing an application of magnetic metal composite aerogel in electromagnetic shielding.

[0056] Figure 4 These are the EMI performance curves of samples 1, 2, 3 and the control sample in the test examples of this invention.

[0057] The layered porous characteristics of the material originate from its graphene composite framework. This structure promotes multiple reflections and scatterings of electromagnetic waves within the material, converting energy into heat and dissipating it, thus reducing the amount of electromagnetic waves that penetrate the material and improving shielding effectiveness. Furthermore, immersion in an MXene solution allows a uniform layer of MXene two-dimensional nanomaterials to adhere to the internal cavity of the material. The transition metal carbides within the MXene structure form conductive channels, facilitating electron migration and improving conductivity. In addition, cobalt metal possesses high electrical and magnetic conductivity; adding appropriate amounts of Co magnetic particle composites can enhance the material's electrical and magnetic properties, strengthening its conductivity against electromagnetic waves and thereby improving the shielding effect. Figure 4 As shown, optimal shielding performance can be obtained by optimizing each component. Specifically, the shielding performance of samples 1, 2, and 3 are 31.7 dB, 42.2 dB, and 36.5 dB, respectively. Therefore, compared with the shielding performance of the control sample of 22.0 dB, the samples prepared in the examples all achieved excellent shielding performance.

[0058] In summary, metallic magnetic Co / graphene / MXene composite aerogels with different properties can be prepared through simple chemical reactions and heat treatment processes, and the proportions of components with excellent electromagnetic shielding performance can be screened out. The process parameters can effectively control the phase composition of the Co / graphene / MXene composite material and regulate its shielding performance, thus facilitating industrial production and holding significant importance for the development and widespread application of electromagnetic shielding materials.

[0059] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a magnetic metal composite aerogel, characterized by, The method comprises the following steps: S10, dissolving cobalt salt and 2,5-dihydroxyterephthalic acid in a solvent to carry out a hydrothermal reaction to obtain a cobalt metal organic framework; S20, carbonizing the cobalt metal organic framework to obtain a Co / C aerogel, comprising the following sub-steps: S21, mixing the cobalt metal organic framework, graphene, chitosan and ethanol in a solvent to prepare a Co / C composite solution; S22, freeze-drying the Co / C composite solution and then heating under an inert atmosphere to obtain the Co / C aerogel; S30, immersing the Co / C aerogel in a MXene solution to obtain the magnetic metal composite aerogel.

2. The method according to claim 1, wherein: in step S10, the cobalt salt comprises cobalt acetate tetrahydrate and / or cobalt chloride tetrahydrate, and the solvent comprises any one or more of anhydrous ethanol, methanol or deionized water. wherein 3. The method according to claim 1 or 2, wherein: step S10 comprises the following sub-steps: S11, mixing a cobalt salt solution and a 2,5-dihydroxyterephthalic acid solution and then stirring to obtain a reaction solution; wherein S12, adding water to the reaction solution and then carrying out a hydrothermal reaction to prepare a solution of the cobalt metal organic framework.

4. The method according to claim 3, wherein: in step S11, the concentration of the cobalt salt in the cobalt salt solution is 20-40 mg / mL, the concentration of 2,5-dihydroxyterephthalic acid in the 2,5-dihydroxyterephthalic acid solution is 2-10 mg / mL, and the volume ratio of the cobalt salt solution to the 2,5-dihydroxyterephthalic acid solution is (1-8):(1-4), and the stirring time is 2 h, in step S12, the volume ratio of the amount of water to the reaction solution is (1-3):(1-9), and the hydrothermal reaction conditions are as follows: increasing the temperature to 50-180℃ at a rate of 1℃ / min-10℃ / min and then maintaining the temperature for 12-24 h.

5. The method according to claim 1, wherein: in step S21, the mass of the cobalt metal organic framework is denoted as m1, and the mass of the graphene is denoted as m2, and m1:m2=1:(4-10), wherein, in step S22, the inert atmosphere is argon, and the heating method is as follows: increasing the temperature to 500-900℃ at a rate of 2℃ / min-10℃ / min and then maintaining the temperature for 60-180 min.

6. The method according to claim 5, wherein: in step S30, the immersion method is as follows: uniformly adding the MXene solution to the surface of the Co / C aerogel until the MXene solution precipitates from the bottom of the Co / C aerogel, and the Co / C aerogel is converted into a Co / C / MXene composite aerogel, i.e. the magnetic metal composite aerogel, in step S30, the mass of the MXene in the MXene solution is denoted as m3, and m1:m3=1:(0.01-0.2). wherein ​ ​ ​ wherein ​ ​ 7. A magnetic metal composite aerogel, characterized by, The magnetic metal composite aerogel is prepared by the method according to any one of claims 1-6.

8. The use of the magnetic metal composite aerogel according to claim 7 in electromagnetic shielding, wherein, The electromagnetic shielding performance of the magnetic metal composite aerogel is 20-50 dB.

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