Preparation method of electromagnetic shielding aerogel and electromagnetic shielding aerogel

Abstract

The invention relates to a preparation method of electromagnetic shielding aerogel and the electromagnetic shielding aerogel. The preparation method comprises the following steps: preparing CoNi-coated Zn-ZIFs; carrying out pyrolysis for 2 hours to obtain CoNi-HCN; preparing a PVA-CF deionized water solution; the preparation method comprises the following steps: dissolving CoNi-HCN in a PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion liquid; the PVA-CF / CoNi-HCN dispersion liquid is placed in a mold, and a first aerogel layer is formed; the preparation method comprises the following steps: dissolving Ti < 3 > C < 2 > T < x > MXene in a PVA-CF deionized water solution to obtain a PVA-CF / Ti < 3 > C < 2 > T < x > MXene dispersion liquid; the PVA-CF / Ti < 3 > C < 2 > T < x > MXene dispersion liquid is placed in a mold, and a second aerogel layer is formed; the first aerogel layer and the second aerogel layer are stacked in a hot press for hot pressing to form electromagnetic shielding aerogel, and the high-absorption and low-reflection material is formed.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of electromagnetic shielding aerogels, and in particular to a method for preparing electromagnetic shielding aerogels and the electromagnetic shielding aerogels. Background Art

[0002] With the rapid development of modern electronic technology, the application of electromagnetic waves has become more and more extensive, from wireless communications to radar systems to household appliances. However, the widespread use of electromagnetic waves has also brought about problems of electromagnetic interference and electromagnetic compatibility. In order to reduce electromagnetic interference, protect sensitive equipment from external electromagnetic waves, and prevent the electromagnetic waves generated by the equipment itself from affecting the outside world, the development of electromagnetic shielding materials has become crucial.

[0003] Traditional electromagnetic shielding materials mainly include metal sheets, metal coatings, conductive polymers and conductive composite materials. These materials usually shield electromagnetic waves through two mechanisms: reflection and absorption. The reflection mechanism relies on the high conductivity of the material to reflect the incident electromagnetic waves back; while the absorption mechanism relies on the magnetic loss and dielectric loss inside the material to convert the electromagnetic wave energy into heat energy and consume it. However, these traditional materials often have certain limitations in terms of shielding effectiveness, weight, cost, and processability.

[0004] In recent years, aerogel, as a new type of porous nanomaterial, has attracted widespread attention due to its ultra-low density, high specific surface area, good thermal insulation and adjustable dielectric properties. The pore structure of aerogel can effectively scatter and absorb electromagnetic waves, thus having potential electromagnetic shielding capabilities. However, the electromagnetic wave shielding effectiveness of ordinary aerogel materials is often insufficient, and the reflection ability is difficult to meet the needs of practical applications. Therefore, it is particularly important to develop a method for preparing electromagnetic shielding aerogel with high electromagnetic wave shielding effectiveness and low reflection ability. Summary of the invention

[0005] In view of the above problems, the embodiments of the present invention provide a method for preparing an electromagnetic shielding aerogel and an electromagnetic shielding aerogel, which overcome the above problems or at least partially solve the above problems.

[0006] According to one aspect of an embodiment of the present invention, a method for preparing an electromagnetic shielding aerogel is provided, comprising: preparing CoNi@Zn-ZIFs; placing the prepared CoNi@Zn-ZIFs in a tubular furnace filled with nitrogen for pyrolysis for 2 hours to obtain CoNi-HCN, wherein the heating slope of the tubular furnace is 2°C min -1, the pyrolysis temperature is 800° C.; preparing a PVA-CF deionized water solution; dissolving the CoNi-HCN in the PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion, wherein the mass ratio of the CoNi-HCN to the PVA-CF deionized water solution is between 0.1:5 and 0.3:5; placing the PVA-CF / CoNi-HCN dispersion in a mold, and freeze-drying to form a first aerogel layer; 3 C 2 T x MXene is dissolved in the PVA-CF deionized water solution to obtain PVA-CF / Ti 3 C 2 T x MXene dispersion, wherein the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is between 0.2:5 and 0.5:5; 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer; the first aerogel layer and the second aerogel layer are stacked and placed in a hot press to form the electromagnetic shielding aerogel, wherein the hot pressing temperature is 80° C. and the hot pressing time is 5 minutes.

[0007] In an optional manner, the method for preparing CoNi@Zn-ZIFs further includes: preparing Zn-ZIFs; dissolving the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate in methanol, stirring at room temperature for 24 hours to obtain a first precipitate, wherein the mass ratio of the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate is 50:292:291, wherein 0.5 grams of the Zn-ZIFs corresponds to 100 milliliters of the methanol; using methanol to centrifuge to collect the first precipitate, and vacuum drying at 80°C for 12 hours to obtain the CoNi@Zn-ZIFs.

[0008] In an optional manner, the method for preparing Zn-ZIFs further includes: dissolving zinc nitrate hexahydrate and 2-methylimidazole in 100 ml of methanol, stirring at room temperature for 24 hours to obtain a second precipitate, wherein the mass ratio of the zinc nitrate hexahydrate to the 2-methylimidazole is 595:616, wherein 5.95 grams of the zinc nitrate hexahydrate corresponds to 100 ml of the methanol; using methanol to centrifuge to collect the second precipitate, and vacuum drying at 80°C for 12 hours to obtain the Zn-ZIFs.

[0009] In an optional manner, the method for preparing a PVA-CF deionized water solution comprises: selecting CF within 30 meshes, washing the CF with ultrapure water and drying it; dissolving PVA powder and the dried CF in deionized water, and stirring at 90° C. for 2 hours to obtain the PVA-CF deionized water solution; wherein the mass ratio of the PVA powder to the dried CF is 4:1; wherein 4 grams of the PVA powder corresponds to 100 milliliters of the deionized water.

[0010] In an optional manner, the method of selecting CF within 30 mesh, washing the CF with ultrapure water and drying the CF further includes: crushing the raw material CF with a pulverizer, and sifting out the CF within 30 mesh with a mesh sieve; washing the CF with ultrapure water for 12 hours and drying it at 45°C.

[0011] In an optional manner, the mass ratio of the CoNi-HCN and the PVA-CF deionized water solution is 0.3:5.

[0012] In an optional manner, the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is 0.5:5.

[0013] In an optional manner, the step of placing the PVA-CF / CoNi-HCN dispersion in a mold and freeze-drying to form the first aerogel layer further includes placing the PVA-CF / CoNi-HCN dispersion in a mold, standing for 30 minutes, and freeze-drying in a freeze dryer at -48°C and 10 Pa for 36 hours to form the first aerogel layer.

[0014] In an optional manner, the PVA-CF / Ti 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer, further comprising: 3 C 2 T x The MXene dispersion was placed in a mold, allowed to stand for 30 minutes, and then freeze-dried in a freeze dryer at -48°C and 10 Pa for 36 hours to form the second aerogel layer.

[0015] According to another aspect of an embodiment of the present invention, an electromagnetic shielding aerogel is provided. The electromagnetic shielding aerogel is prepared using the above-mentioned method for preparing the electromagnetic shielding aerogel.

[0016] The beneficial effects of the embodiments of the present invention include providing a method for preparing an electromagnetic shielding aerogel, comprising: preparing CoNi@Zn-ZIFs; placing the prepared CoNi@Zn-ZIFs in a tubular furnace filled with nitrogen for pyrolysis for 2 hours to obtain CoNi-HCN, wherein the heating slope of the tubular furnace is 2°C min -1 , the pyrolysis temperature is 800° C.; preparing a PVA-CF deionized water solution; dissolving the CoNi-HCN in the PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion, wherein the mass ratio of the CoNi-HCN to the PVA-CF deionized water solution is between 0.1:5 and 0.3:5; placing the PVA-CF / CoNi-HCN dispersion in a mold, and freeze-drying to form a first aerogel layer; 3 C 2 T x MXene is dissolved in the PVA-CF deionized water solution to obtain PVA-CF / Ti 3 C 2 T x MXene dispersion, wherein the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is between 0.2:5 and 0.5:5; 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer; the first aerogel layer and the second aerogel layer are stacked and placed in a hot press to form the electromagnetic shielding aerogel, wherein the hot pressing temperature is 80°C and the hot pressing time is 5 minutes. The electromagnetic shielding aerogel prepared by the preparation method of the electromagnetic shielding aerogel forms a unique two-layer structure, which is conducive to the process of electromagnetic waves along the absorption-reflection-reabsorption. The porous structure of the aerogel will reduce the impedance mismatch phenomenon, absorb more electromagnetic waves, and Ti 3 C 2 T x MXene can conduct electrical losses, and CoNi particles can conduct magnetic losses to electromagnetic waves, forming a high-absorption, low-reflection material with an electromagnetic shielding effectiveness of up to 43.5dB. At the same time, the reflection coefficient can reach 0.17. In addition, outdoor electronic devices can also work normally in extremely cold weather conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0018] Figure 1 It is a schematic flow chart of a method for preparing an electromagnetic shielding aerogel provided by an embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the process of preparing CoNi@Zn-ZIFs provided in an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the process of preparing Zn-ZIFs provided in an embodiment of the present invention;

[0021] Figure 4 1 is a schematic diagram of a process for preparing a PVA-CF deionized water solution provided in an embodiment of the present invention;

[0022] Figure 5 It is a schematic diagram of the process for preparing CF provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The present invention provides a method for preparing an electromagnetic shielding aerogel. Figure 1 , the method comprises the following steps:

[0025] Step S10, preparing CoNi@Zn-ZIFs.

[0026] It is worth noting that, in some embodiments, see Figure 2 , the method for preparing CoNi@Zn-ZIFs comprises the following steps:

[0027] Step S101, preparing Zn-ZIFs.

[0028] The Zn-ZIFs are zinc-based zeolite imidazolate frameworks, which are metal-organic frameworks. Zn-ZIFs are formed by self-assembly of zinc ions and imidazole organic ligands, and have porosity, high specific surface area and abundant metal active sites.

[0029] It is worth noting that, in some embodiments, see Figure 3 , the method for preparing Zn-ZIFs further comprises the following steps:

[0030] Step S1011, dissolving zinc nitrate hexahydrate and 2-methylimidazole in 100 ml of methanol, stirring at room temperature for 24 hours to obtain a second precipitate.

[0031] The mass ratio of the zinc nitrate hexahydrate to the 2-methylimidazole is 595:616, wherein 5.95 grams of the zinc nitrate hexahydrate corresponds to 100 milliliters of the methanol.

[0032] Step S1012, using methanol to collect the second precipitate by centrifugation, and vacuum drying at 80° C. for 12 hours to obtain the Zn-ZIFs.

[0033] Step S102, dissolving the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate in methanol, stirring at room temperature for 24 hours to obtain a first precipitate.

[0034] The mass ratio of the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate is 50:292:291, wherein 0.5 g of the Zn-ZIFs corresponds to 100 ml of the methanol.

[0035] Step S103, using methanol to collect the first precipitate by centrifugation, and vacuum drying at 80° C. for 12 hours to obtain the CoNi@Zn-ZIFs.

[0036] Step S20, placing the prepared CoNi@Zn-ZIFs in a tubular furnace filled with nitrogen for pyrolysis for 2 hours to obtain CoNi-HCN, wherein the heating ramp of the tubular furnace is 2°C min -1 , the pyrolysis temperature is 800°C.

[0037] Step S30, preparing a PVA-CF deionized water solution.

[0038] Among them, PVA refers to polyvinyl alcohol (Polyvinyl Alcohol), which is a common water-soluble high molecular polymer.

[0039] Among them, CF is carbon fiber, which is a high-strength, high-modulus fiber material mainly composed of carbon elements and has excellent mechanical properties and chemical stability.

[0040] It is worth noting that, in some embodiments, see Figure 4 The method for preparing a deionized PVA-CF aqueous solution further comprises the following steps:

[0041] Step S301, select CF within 30 mesh, wash the CF with ultrapure water and dry it.

[0042] Among them, ultrapure water refers to water in which impurities and ions have been removed to an extremely high degree. Its resistivity is usually greater than 18 megohm-cm and it is widely used in laboratories, semiconductor production and other fields.

[0043] It is worth noting that, in some embodiments, see Figure 5 The method of selecting CF within 30 meshes, washing the CF with ultrapure water and drying it further comprises the following steps:

[0044] Step S3011, crush the raw material CF with a crusher, and use a mesh sieve to screen out the CF within 30 meshes.

[0045] Step S3012, washing the CF with ultrapure water for 12 hours and drying at 45°C.

[0046] Step S302, dissolving the PVA powder and the dried CF in deionized water, and stirring at 90° C. for 2 hours to obtain the PVA-CF deionized water solution.

[0047] Wherein, the mass ratio of the PVA powder to the dried CF is 4:1.

[0048] Wherein, 4 grams of the PVA powder corresponds to 100 milliliters of the deionized water.

[0049] Step S40, dissolving the CoNi-HCN in the PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion.

[0050] Wherein, the mass ratio of the CoNi-HCN and the PVA-CF deionized water solution is between 0.1:5 and 0.3:5.

[0051] It is worth noting that, in some embodiments, the mass ratio of the CoNi-HCN and the PVA-CF deionized water solution is 0.3:5.

[0052] It is worth noting that after the CoNi-HCN is dissolved in the PVA-CF deionized water solution, it is ultrasonicated for 12 minutes using an ultrasonic wave with a power of 400 W to obtain the PVA-CF / CoNi-HCN dispersion.

[0053] Step S50, placing the PVA-CF / CoNi-HCN dispersion in a mold and freeze-drying it to form a first aerogel layer.

[0054] The mold can be a polytetrafluoroethylene mold.

[0055] The mold is used to distribute the PVA-CF / CoNi-HCN dispersion into a film. The mold is used to control the thickness and morphology of the first aerogel layer formed, thereby giving the final product specific physical and chemical properties.

[0056] It is worth noting that, in some embodiments, the step of placing the PVA-CF / CoNi-HCN dispersion in a mold and freeze-drying to form a first aerogel layer further includes placing the PVA-CF / CoNi-HCN dispersion in a mold, standing for 30 minutes, and then freeze-drying in a freeze dryer at -48°C and 10 Pa for 36 hours to form the first aerogel layer.

[0057] Step S60: Ti 3 C 2 T x MXene is dissolved in the PVA-CF deionized water solution to obtain PVA-CF / Ti 3 C 2 T x MXene dispersion.

[0058] Among them, the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is between 0.2:5 and 0.5:5.

[0059] It is worth noting that, in some embodiments, the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is 0.5:5.

[0060] It is worth noting that the Ti 3 C 2 T x After MXene was dissolved in the PVA-CF deionized water solution, it was ultrasonicated for 12 minutes using an ultrasonic wave with a power of 400 W to obtain the PVA-CF / Ti 3 C 2 T x MXene dispersion.

[0061] Among them, MXene has high conductivity, large specific surface area and good hydrophilicity, which makes it have broad application prospects in energy storage, catalysis, sensing and biomedicine. The general formula of MXene is Mn+1XnTx, where "M" represents early transition metals, "X" represents carbon and / or nitrogen, and "Tx" represents surface groups. In the embodiment of the present application, MXene can be Ti3 C 2 T x Nano aerogel.

[0062] Step S70, the PVA-CF / Ti 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form the second aerogel layer.

[0063] The mold can be a polytetrafluoroethylene mold.

[0064] Among them, the use of the mold is to make PVA-CF / Ti 3 C 2 T x The MXene dispersion is distributed into a film. Through the mold, it is easy to control the thickness and morphology of the second aerogel layer formed, thus giving the final product specific physical and chemical properties.

[0065] It is worth noting that, in some embodiments, the PVA-CF / Ti 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer, further comprising: 3 C 2 T x The MXene dispersion was placed in a mold, allowed to stand for 30 minutes, and then freeze-dried in a freeze dryer at -48°C and 10 Pa for 36 hours to form the second aerogel layer.

[0066] Step S80, stacking the first aerogel layer and the second aerogel layer in a hot press and hot pressing them to form the electromagnetic shielding aerogel, wherein the hot pressing temperature is 80° C. and the hot pressing time is 5 minutes.

[0067] In an embodiment of the present application, a method for preparing an electromagnetic shielding aerogel is provided, comprising: preparing CoNi@Zn-ZIFs; placing the prepared CoNi@Zn-ZIFs in a tubular furnace filled with nitrogen for pyrolysis for 2 hours to obtain CoNi-HCN, wherein the heating slope of the tubular furnace is 2°C min -1 , the pyrolysis temperature is 800° C.; preparing a PVA-CF deionized water solution; dissolving the CoNi-HCN in the PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion, wherein the mass ratio of the CoNi-HCN to the PVA-CF deionized water solution is between 0.1:5 and 0.3:5; placing the PVA-CF / CoNi-HCN dispersion in a mold, and freeze-drying to form a first aerogel layer;3 C 2 T x MXene is dissolved in the PVA-CF deionized water solution to obtain PVA-CF / Ti 3 C 2 T x MXene dispersion, wherein the Ti 3 C 2 T x The mass ratio of MXene to the PVA-CF deionized water solution is between 0.2:5 and 0.5:5; 3 C 2 T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer; the first aerogel layer and the second aerogel layer are stacked and placed in a hot press to form the electromagnetic shielding aerogel, wherein the hot pressing temperature is 80°C and the hot pressing time is 5 minutes. The electromagnetic shielding aerogel prepared by the preparation method of the electromagnetic shielding aerogel forms a unique two-layer structure, which is conducive to the process of electromagnetic waves along the absorption-reflection-reabsorption. The porous structure of the aerogel will reduce the impedance mismatch phenomenon, absorb more electromagnetic waves, and Ti 3 C 2 T x MXene can achieve excellent conductive loss, and CoNi particles can achieve magnetic loss of electromagnetic waves, forming a high-absorption and low-reflection material with an electromagnetic shielding effectiveness between 35.1 and 43.5 dB, while the reflection coefficient is between 0.28 and 0.17. In addition, outdoor electronic devices can also work normally in extremely cold weather conditions.

[0068] The embodiment of the present application also provides an electromagnetic shielding aerogel, and the electromagnetic shielding aerogel is prepared using the preparation method of the electromagnetic shielding aerogel in the above embodiment.

[0069] In order to help readers understand the inventive concept of the embodiments of the present invention, the technical effects of using the embodiments of the present invention are demonstrated as follows.

[0070] Embodiment 1

[0071] <Preparation of CoNi-HCN>

[0072] Zinc nitrate hexahydrate (5.95 g) and 2-methylimidazole (6.16 g) were dissolved in 100 ml of methanol. The mixture was stirred at room temperature for 24 h. The precipitate was collected by centrifugation with methanol and then dried under vacuum at 80 °C for 12 h to obtain Zn-ZIFs.

[0073] Zn-ZIFs (0.50 g), nickel nitrate hexahydrate (2.91 g) and cobalt nitrate hexahydrate (2.91 g) were dissolved in 100 ml of methanol. The mixture was stirred at room temperature for 24 h. The precipitate was collected by centrifugation with methanol and then dried under vacuum at 80 °C for 12 h to obtain CoNi@Zn-ZIFs.

[0074] The synthesized CoNi@Zn-ZIFs were placed in a tubular furnace filled with nitrogen, heated to 800 °C with a heating ramp of 2 °C min-1, and maintained at 800 °C for 2 h for pyrolysis to obtain CoNi-HCN.

[0075] <Preparation of PVA-CF deionized water solution>

[0076] The CF was crushed with a pulverizer and sieved with a mesh screen to obtain CF within 30 mesh, washed with ultrapure water for 12 hours, and dried at 45° C. PVA powder (0.4 g) and dried CF (0.1 g) were dissolved in 10 ml of deionized water and stirred at 90° C. for 2 hours to obtain a light yellow PVA-CF deionized water solution.

[0077] The CF was crushed with a pulverizer and sieved with a mesh screen to obtain CF within 30 mesh, washed with ultrapure water for 12 hours, and dried at 45° C. PVA powder (0.4 g) and dried CF (0.1 g) were dissolved in 10 ml of deionized water and stirred at 90° C. for 2 hours to obtain a light yellow PVA-CF deionized water solution.

[0078] <Preparation of First Aerogel Layer and Second Aerogel Layer>

[0079] CoNi-HCN was added to the above-mentioned PVA-CF deionized water solution (the mass ratio of CoNi-HCN and PVA-CF deionized water solution was 0.1:5), and ultrasonic treatment was performed at a power of 400 W for 12 minutes to obtain a PVA-CF / CoNi-HCN dispersion. The PVA-CF / CoNi-HCN dispersion was transferred to a customized polytetrafluoroethylene mold, allowed to stand for 30 minutes, and then freeze-dried in a freeze dryer (-48°C, 10 Pa) for 36 hours to form the first aerogel layer.

[0080] Ti 3 C 2 T x MXene was added to the above PVA-CF deionized water solution (Ti 3 C 2 T x The mass ratio of MXene and PVA-CF deionized water solution was 0.2:5), and ultrasonic treatment was performed at a power of 400W for 12 minutes to obtain PVA-CF / Ti 3 C 2 Tx MXene dispersion, PVA-CF / Ti 3 C 2 T x The MXene dispersion was transferred into a custom polytetrafluoroethylene mold and, after standing for 30 min, freeze-dried in a freeze dryer (−48 °C, 10 Pa) for 36 h to form the second aerogel layer.

[0081] <Preparation of electromagnetic shielding aerogel>

[0082] The first aerogel layer and the second aerogel layer are stacked in a hot press, wherein the hot pressing temperature is 80° C. and the hot pressing time is 5 min to obtain a high-absorption and low-reflection electromagnetic shielding aerogel.

[0083] Embodiment 2

[0084] <Preparation of CoNi-HCN>

[0085] Same as Example 1.

[0086] <Preparation of PVA-CF deionized water solution>

[0087] Same as Example 1.

[0088] <Preparation of First Aerogel Layer and Second Aerogel Layer>

[0089] CoNi-HCN was added to the above-mentioned PVA-CF deionized water solution (the mass ratio of CoNi-HCN and PVA-CF deionized water solution was 0.3:5), and ultrasonic treatment was performed at a power of 400 W for 12 minutes to obtain a PVA-CF / CoNi-HCN dispersion. The PVA-CF / CoNi-HCN dispersion was transferred to a customized polytetrafluoroethylene mold, allowed to stand for 30 minutes, and then freeze-dried in a freeze dryer (-48°C, 10 Pa) for 36 hours to form the first aerogel layer.

[0090] Ti 3 C 2 T x MXene was added to the above PVA-CF deionized water solution (Ti 3 C 2 T x The mass ratio of MXene and PVA-CF deionized water solution was 0.5:5), and ultrasonic treatment was performed at a power of 400W for 12 minutes to obtain PVA-CF / Ti 3 C 2 T x MXene dispersion, PVA-CF / Ti 3 C 2 T xThe MXene dispersion was transferred into a custom polytetrafluoroethylene mold and, after standing for 30 min, freeze-dried in a freeze dryer (−48 °C, 10 Pa) for 36 h to form the second aerogel layer.

[0091] <Preparation of electromagnetic shielding aerogel>

[0092] Same as Example 1.

[0093] Comparative Example 1

[0094] <Preparation of CoNi-HCN>

[0095] Same as Example 1.

[0096] <Preparation of PVA-CF deionized water solution>

[0097] Same as Example 1.

[0098] <Preparation of electromagnetic shielding aerogel>

[0099] CoNi-HCN and Ti 3 C 2 T x MXene was added to the deionized water solution of PVA-CF, CoNi-HCN, Ti 3 C 2 T x The mass ratio of the deionized water solution of PVA-CF was 0.1:0.2:5, and the ultrasonic treatment was carried out at a power of 400W for 12 minutes to obtain PVA-CF / Ti 3 C 2 T x MXene / CoNi-HCN dispersion, PVA-CF / Ti 3 C 2 T x The MXene / CoNi-HCN dispersion was transferred into a custom polytetrafluoroethylene mold and, after standing for 30 min, freeze-dried in a freeze dryer (-48 °C, 10 Pa) for 36 h to form an electromagnetic shielding aerogel.

[0100] The electromagnetic shielding performance of the electromagnetic shielding aerogels prepared in Example 1, Example 2 and Comparative Example 1 was tested respectively, and the test results are shown in Table 1 below:

[0101] Table 1. Electromagnetic shielding performance of electromagnetic shielding aerogels

[0102] Electromagnetic shielding aerogel Electromagnetic shielding effectiveness (dB) Reflection coefficient Embodiment 1 35.1 0.28 Embodiment 2 43.5 0.17 Comparative Example 1 32.2 0.62

[0103] From Table 1, the electromagnetic shielding aerogel prepared in the present application has electromagnetic shielding performance with high absorption and low reflection. The electromagnetic shielding aerogel prepared in the present application introduces a variety of electromagnetic wave loss mechanisms to achieve the purpose of absorbing electromagnetic waves. Among them, the electromagnetic shielding effectiveness of the electromagnetic shielding aerogel in Example 1 can reach 35.1dB, and the reflection coefficient is 0.28. Among them, the electromagnetic shielding effectiveness of the electromagnetic shielding aerogel in Example 2 can reach 43.5dB, and the reflection coefficient is only 0.17. Among them, the shielding effectiveness of the aerogel in Comparative Example 1 can reach 32.2dB, but the reflection coefficient is 0.62, and the electromagnetic waves have the possibility of secondary pollution. In addition, under two sunlight intensities, the temperature of the electromagnetic shielding aerogel in Example 1 and Example 2 can reach 102.3°C. This electromagnetic shielding aerogel integrates photothermal conversion capabilities, which can further improve the stability and reliability of the equipment.

[0104] It is worth noting that the high absorption and low reflectivity of the electromagnetic shielding aerogel provided in the embodiment of the present application comes from the unique double-layer structure, which is conducive to the absorption-reflection-reabsorption process of electromagnetic waves. The porous structure of the aerogel can reduce the impedance mismatch phenomenon and absorb more electromagnetic waves. 3 C 2 T x MXene can perform excellent conductive loss, and CoNi particles can perform magnetic loss on electromagnetic waves, forming a material with high absorption and low reflection.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an electromagnetic shielding aerogel, characterized in that: include: Preparation of CoNi@Zn-ZIFs; The prepared CoNi@Zn-ZIFs were placed in a tubular furnace filled with nitrogen and pyrolyzed for 2 hours to obtain CoNi-HCN, wherein the heating ramp of the tubular furnace was 2 °C min -1 , the pyrolysis temperature is 800°C; Prepare a PVA-CF deionized water solution; Dissolving the CoNi-HCN in the PVA-CF deionized water solution to obtain a PVA-CF / CoNi-HCN dispersion, wherein the mass ratio of the CoNi-HCN to the PVA-CF deionized water solution is between 0.1:5 and 0.3:5; Placing the PVA-CF / CoNi-HCN dispersion in a mold and freeze-drying to form a first aerogel layer; Ti3C2T x MXene was dissolved in the PVA-CF deionized water solution to obtain PVA-CF / Ti3C2T x MXene dispersion, wherein the Ti3C2T x The mass ratio of MXene to the PVA-CF deionized water solution is between 0.2:5 and 0.5:5; The PVA-CF / Ti3C2T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer; The first aerogel layer and the second aerogel layer are stacked and placed in a hot press to form the electromagnetic shielding aerogel, wherein the hot pressing temperature is 80° C. and the hot pressing time is 5 minutes.

2. The method for preparing the electromagnetic shielding aerogel according to claim 1, characterized in that: The method for preparing CoNi@Zn-ZIFs further comprises: Preparation of Zn-ZIFs; Dissolving the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate in methanol, stirring at room temperature for 24 hours to obtain a first precipitate, wherein the mass ratio of the Zn-ZIFs, nickel nitrate hexahydrate and cobalt nitrate hexahydrate is 50:292:291, wherein 0.5 g of the Zn-ZIFs corresponds to 100 ml of the methanol; The first precipitate was collected by centrifugation using methanol and dried under vacuum at 80° C. for 12 hours to obtain the CoNi@Zn-ZIFs.

3. The method for preparing the electromagnetic shielding aerogel according to claim 2, characterized in that: The method for preparing Zn-ZIFs further comprises: Dissolving zinc nitrate hexahydrate and 2-methylimidazole in 100 ml of methanol, stirring at room temperature for 24 hours to obtain a second precipitate, wherein the mass ratio of the zinc nitrate hexahydrate to the 2-methylimidazole is 595:616, wherein 5.95 g of the zinc nitrate hexahydrate corresponds to 100 ml of the methanol; The second precipitate was collected by centrifugation using methanol and dried under vacuum at 80° C. for 12 hours to obtain the Zn-ZIFs.

4. The method for preparing the electromagnetic shielding aerogel according to claim 3, characterized in that: The method for preparing a deionized water solution of PVA-CF comprises: Select CF within 30 mesh, wash the CF with ultrapure water and dry it; Dissolving the PVA powder and the dried CF in deionized water, and stirring at 90° C. for 2 hours to obtain the PVA-CF deionized water solution; Wherein, the mass ratio of the PVA powder to the dried CF is 4:1; Wherein, 4 grams of the PVA powder corresponds to 100 milliliters of the deionized water.

5. The method for preparing the electromagnetic shielding aerogel according to claim 4, characterized in that: The method of selecting CF within 30 meshes, washing the CF with ultrapure water and drying it further comprises: The raw material CF is crushed by a crusher, and the CF with a mesh size of less than 30 mesh is sieved by a mesh sieve; The CF was washed with ultrapure water for 12 hours and dried at 45°C.

6. The method for preparing the electromagnetic shielding aerogel according to any one of claims 1 to 5, characterized in that: The mass ratio of the CoNi-HCN and the PVA-CF deionized water solution is 0.3:

5.

7. The method for preparing the electromagnetic shielding aerogel according to claim 6, characterized in that: The Ti3C2T x The mass ratio of MXene to the PVA-CF deionized water solution is 0.5:

5.

8. The method for preparing the electromagnetic shielding aerogel according to claim 7, characterized in that: The step of placing the PVA-CF / CoNi-HCN dispersion in a mold and freeze-drying to form the first aerogel layer further includes placing the PVA-CF / CoNi-HCN dispersion in a mold, standing for 30 minutes, and freeze-drying in a freeze dryer at -48°C and 10 Pa for 36 hours to form the first aerogel layer.

9. The method for preparing the electromagnetic shielding aerogel according to claim 8, characterized in that: The PVA-CF / Ti3C2T x The MXene dispersion is placed in a mold and freeze-dried to form a second aerogel layer, further comprising: x The MXene dispersion was placed in a mold, allowed to stand for 30 minutes, and then freeze-dried in a freeze dryer at -48°C and 10 Pa for 36 hours to form the second aerogel layer.

10. An electromagnetic shielding aerogel, characterized in that: The electromagnetic shielding aerogel is prepared using the method for preparing the electromagnetic shielding aerogel according to any one of claims 1 to 9.

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