A three-dimensional ordered parallel lamellar structure aerogel and its preparation method and application

Abstract

The present invention discloses a method for preparing a three-dimensional ordered parallel lamellar aerogel, comprising: carbonizing a chitosan / graphene oxide aerogel to obtain a parallel lamellar carbon / reduced graphene oxide aerogel; and loading the parallel lamellar carbon / reduced graphene oxide aerogel with a petal-shaped SnS2 structure to obtain a three-dimensional ordered parallel lamellar aerogel. The present invention also discloses the three-dimensional ordered parallel lamellar aerogel prepared using the above method and its application. The present invention prepares a three-dimensional ordered parallel lamellar aerogel by combining multiple component materials with ingenious structural design. The three-dimensional parallel lamellar structure, petal-shaped SnS2, and heterogeneous C / rGO interface of the aerogel work synergistically to impart excellent electromagnetic wave absorption performance to the aerogel. The absorbing material prepared using the aerogel has the characteristics of low density, low filling ratio, strong absorption, and ultra-wideband absorption, and has broad application prospects in the field of electromagnetic absorption.

Description

Technical Field

[0001] The present invention belongs to the technical field of wave-absorbing materials, and in particular relates to a three-dimensional ordered parallel sheet structure aerogel and a preparation method and application thereof. Background Art

[0002] With the rapid development of smart devices and communication technology, electromagnetic pollution has posed a serious threat to information security and human health. Exploring electromagnetic wave absorbing materials with thin, light, wide and strong characteristics is an urgent problem that needs to be solved.

[0003] Traditional microwave absorbing materials, such as metal powders, ceramics, and ferrites, lack the ability to effectively absorb microwaves due to their narrow bandwidth and high density. Designing absorbing materials with ordered, three-dimensional parallel lamellar structures not only prevents absorber aggregation but also, due to the abundant pores between the lamellar structures, extends the propagation path of electromagnetic waves, providing favorable conditions for enhancing electromagnetic wave absorption performance.

[0004] Bidirectional freezing, as an efficient and stable method for preparing three-dimensional ordered lamellar structure aerogels, has outstanding advantages in microstructure regulation. Its essence is the process of using planar oriented ice crystals as a reverse template to reversely replicate their ordered structure, thereby obtaining an ordered lamellar structure.

[0005] The invention patent with authorization announcement number CN 111777841 B discloses a lamellar anisotropic graphene / epoxy resin composite material and its preparation method. The method obtains graphene aerogel by bidirectionally freezing, imidizing and graphitizing a mixed solution of graphene oxide and polyamic acid salt, and then composites and solidifies the graphene aerogel with epoxy resin to obtain a graphene / epoxy resin composite material.

[0006] The invention patent with authorization announcement number CN 114181424 B discloses an aerogel skeleton and its preparation method, and a method for controlling interlayer spacing and layer thickness, comprising: dispersing fluorinated boron nitride nanosheets and graphene oxide in a polyvinyl alcohol aqueous solution or a carboxymethyl cellulose aqueous solution to obtain an aqueous slurry, then placing the aqueous slurry in a mold for bidirectional freezing, and preparing an aerogel skeleton after drying. By changing the water contact angle of the freezing interface and adjusting the solid content of the aqueous slurry, the microstructure of the aerogel skeleton is effectively controlled, thereby preparing aerogel skeletons with different interlayer spacing and layer thicknesses.

[0007] As can be seen from the above-mentioned prior art, lamellar carbon-based aerogels can be obtained using bidirectional freezing technology. However, due to the high electrical conductivity of lamellar carbon-based aerogels, their impedance matching properties are poor, which affects their application in microwave absorption. Therefore, it is crucial to find a method to improve the impedance matching properties of lamellar carbon-based aerogels and thus enhance their microwave absorption performance. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention provides a method for preparing a three-dimensional ordered parallel lamellar structure aerogel. According to the method, carbon-based lamellar aerogel and petal-shaped SnS2 are compounded to prepare the above-mentioned three-dimensional ordered parallel lamellar structure aerogel. The preparation method is simple and easy to operate. The prepared three-dimensional ordered parallel lamellar structure aerogel has excellent electromagnetic wave absorption performance.

[0009] A method for preparing a three-dimensional ordered parallel lamellar structure aerogel comprises the following steps:

[0010] (1) carbonizing chitosan / graphene oxide aerogel to obtain parallel sheet structure carbon / reduced graphene oxide aerogel;

[0011] (2) Petal-shaped SnS2 was loaded on the parallel lamellar carbon / reduced graphene oxide aerogel to obtain a three-dimensional ordered parallel lamellar aerogel.

[0012] The present invention carbonizes chitosan / graphene oxide aerogel through a multi-component composite and ingenious structural design to produce a parallel-lamellar carbon / reduced graphene oxide aerogel (C / rGO). This aerogel is then loaded with petal-shaped SnS2 to create a three-dimensional, parallel-lamellar C / rGO / SnS2 aerogel. The three-dimensional, parallel-lamellar structure, the petal-shaped SnS2, and the heterogeneous C / rGO interface work synergistically, resulting in excellent electromagnetic wave absorption properties through optimized impedance matching, enhanced multiple scattering, and improved interfacial polarization and dipole polarization.

[0013] Preferably, in step (1), the preparation method of the chitosan / graphene oxide aerogel is: uniformly mixing a chitosan solution and a graphene oxide suspension to obtain a chitosan / graphene oxide precursor solution, and bidirectionally freezing and freeze-drying the chitosan / graphene oxide precursor solution to obtain the chitosan / graphene oxide aerogel.

[0014] Preferably, the concentration of the chitosan solution is 5-50 mg / mL, the concentration of the graphene oxide suspension is 2-30 mg / mL, and the mass ratio of the chitosan solution to the graphene oxide suspension is 1:0.1-2.

[0015] Preferably, the bidirectional freezing is: transferring the chitosan / graphene oxide precursor solution into a cold casting mold and freezing it at a temperature of -10 to -196° C. for 30 to 180 minutes.

[0016] Preferably, the freeze-drying step is: freeze-drying the bidirectionally frozen chitosan / graphene oxide precursor solution at -40 to 35° C. for 48 to 72 hours.

[0017] Preferably, in step (1), the carbonization conditions are: heating to 300-1000° C. at a heating rate of 1-10° C. / min under an inert atmosphere, and keeping the temperature for 1-10 h.

[0018] More preferably, the carbonization is carried out in two stages, the temperature conditions of the first stage are: heating to 300-500°C at a heating rate of 1-10°C / min, and keeping warm for 0.5-3h; the carbonization temperature of the second stage is heating to 550-1000°C at a heating rate of 1-10°C / min, and keeping warm for 1-6h.

[0019] Preferably, the inert atmosphere is argon or nitrogen.

[0020] Preferably, in step (2), the method for loading petal-shaped SnS2 on the parallel sheet structure carbon / reduced graphene oxide aerogel is: immersing the parallel sheet structure carbon / reduced graphene oxide aerogel in a tin salt solution, then adding a sulfur-containing compound, heating, standing at room temperature, collecting the precipitate, washing, and drying.

[0021] There are a large number of oxygen-containing functional groups on the surface of parallel sheet carbon / reduced graphene oxide aerogel. The van der Waals force between these functional groups and metal cations causes tin ions to adsorb on the surface of parallel sheet carbon / reduced graphene oxide aerogel. When sulfur-containing compounds are added, the tin ions on the surface of parallel sheet carbon / reduced graphene oxide aerogel combine with sulfur ions in the solution to form SnS2 nanosheets, realizing the in situ growth of SnS2 on parallel sheet carbon / reduced graphene oxide aerogel.

[0022] Since SnS2 has a low electrical conductivity, the composite of SnS2 and carbon-based lamellar aerogel can effectively adjust the electromagnetic parameters of the absorber, thereby improving the microwave absorption performance. At the same time, the petal-like structure of SnS2 provides favorable conditions for enhancing the electromagnetic wave scattering of the composite material.

[0023] Preferably, the heating temperature is 30-80° C. and the heating time is 1-6 hours.

[0024] Preferably, the room temperature standing time is 3 to 48 hours.

[0025] Preferably, the tin salt in the tin salt solution is one of tin nitrate, tin sulfate or tin chloride, the solvent is one of deionized water, anhydrous ethanol or ethylene glycol, and the concentration of the tin salt solution is 0.1-20.0 g / L.

[0026] Preferably, the sulfur-containing compound is one of thiourea or thioacetamide.

[0027] Preferably, the mass ratio of the parallel-sheet carbon / reduced graphene oxide aerogel to the tin salt is 1:1 to 1:20, and the mass ratio of the sulfur-containing compound to the tin salt is 2:1 to 1:2. Within this mass ratio range, uniformly coated C / rGO / SnS2 can be obtained.

[0028] The present invention also provides a three-dimensional ordered parallel lamellar aerogel produced by the above-mentioned preparation method. The three-dimensional ordered parallel lamellar aerogel has a parallel lamellar C / rGO skeleton and a surface uniformly coated with petal-shaped SnS2. It exhibits an ultra-wide electromagnetic wave absorption band, excellent reflection loss, and an extremely low filling ratio.

[0029] The present invention also provides applications of the three-dimensional ordered parallel lamellar aerogel in the field of microwave absorption. The microwave absorbing material prepared using the unique structural characteristics of the aerogel exhibits low density, low filling ratio, strong absorption, and ultra-broadband absorption, and has broad application prospects in the field of microwave absorption.

[0030] An absorbing material is prepared by vacuum impregnation of the aforementioned three-dimensional ordered parallel lamellar aerogel into an organic matrix. This absorbing material exhibits superior electromagnetic wave absorption performance, with a maximum reflection loss of -59.2 dB at a thickness of 1.45 mm, an effective absorption bandwidth of 5.4 GHz, and an ultra-low filling ratio of 6.7 wt% in the organic matrix.

[0031] Preferably, the organic matrix includes at least one of paraffin, silica gel, polydimethylsiloxane, rubber or epoxy resin.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention uses a multi-component material composite and ingenious structural design to prepare C / rGO aerogel with a parallel lamellar structure using chitosan and graphene oxide as raw materials. Petal-shaped SnS2 is then loaded on the aerogel material to prepare a three-dimensional ordered parallel lamellar structure aerogel with uniform SnS2 loading. The preparation method of the present invention is simple and easy to operate. The three-dimensional parallel lamellar structure, petal-shaped SnS2, and heterogeneous C / rGO interface can work synergistically, resulting in the three-dimensional ordered parallel lamellar structure aerogel having good electromagnetic wave absorption performance by optimizing impedance matching, enhancing multiple scattering, and improving interfacial polarization and dipole polarization.

[0034] 2. The three-dimensional ordered parallel sheet structure aerogel prepared by the method of the present invention has an ultra-wide electromagnetic wave absorption band, excellent reflection loss and extremely low filling ratio, and has broad application prospects in the field of absorbing material technology.

[0035] 3. The absorbing material prepared using the three-dimensional ordered parallel lamellar aerogel of the present invention exhibits low density, low filling ratio, strong absorption, and ultra-broadband absorption. The prepared absorbing material exhibits a maximum reflection loss of -59.2 dB at a thickness of 1.45 mm, an effective absorption bandwidth of 5.4 GHz, and an ultra-low filling ratio of 6.7 wt% in the organic matrix. Compared to most currently reported absorbers, it exhibits superior electromagnetic wave absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 These are the XRD patterns of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel prepared in Example 1 and the parallel sheet structure C / rGO aerogel prepared in Comparative Example 1.

[0037] Figure 2 This is the SEM image of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel prepared in Example 1, where Figure 2 (a) is the SEM image of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel with a scale of 1 mm; 2(b) is the SEM image of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel with a scale of 5 μm.

[0038] Figure 3 This is the reflection loss curve of the absorbing material made from the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel in Example 1.

[0039] Figure 4 This is the reflection loss curve of the absorbing material made from the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel in Example 2.

[0040] Figure 5 This is the reflection loss curve of the absorbing material made from the parallel layer structure C / rGO aerogel in Comparative Example 1.

[0041] Figure 6 This is the reflection loss curve of the absorbing material made from SnS2 in Comparative Example 2. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the following examples and accompanying drawings. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0043] Example 1

[0044] The preparation method of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel and the absorbing material in this embodiment is as follows:

[0045] (1) Preparation of parallel layer structure C / rGO aerogel

[0046] 2.4 g of chitosan was dissolved in acetic acid solution (2.4 mL of acetic acid was dissolved in 80 mL of deionized water) and stirred thoroughly to obtain a chitosan solution; 0.36 g of graphene oxide was dispersed in 40 mL of deionized water and ultrasonically treated at 500 W for 30 min to prepare a 9 mg / mL graphene oxide suspension; the chitosan solution and the graphene oxide suspension were mixed and stirred at a speed of 400 r / min for 120 min to obtain a uniform chitosan / graphene oxide precursor solution, which was then poured into a circular mold, placed on a copper platform in a container filled with liquid nitrogen, and bidirectionally frozen. After freezing, the mixture was freeze-dried in a freeze dryer for 60 h to obtain a chitosan / graphene oxide aerogel with a parallel lamellar structure;

[0047] The obtained chitosan / graphene oxide aerogel was placed in a tubular furnace and, under an argon atmosphere, first heated to 500°C at a heating rate of 2°C / min and kept warm for 1 h, then heated to 800°C at a heating rate of 5°C / min and kept warm for 2 h to obtain C / rGO aerogel.

[0048] (2) Loading petal-shaped SnS2 on parallel layer structure C / rGO aerogel

[0049] 0.3261 g of tin tetrachloride was dispersed in 50 mL of ethanol and stirred for 60 min to obtain solution A. 50 mg of parallel lamellar structure C / rGO aerogel was immersed in solution A, and 0.2025 g of thioacetamide was added and stirred evenly. The solution was heated to 48 ° C and maintained for 3 h. Then, it was placed at room temperature for 24 h. The precipitate was collected and washed with ethanol three times. The precipitate was dried in an oven at 40 ° C overnight to obtain C / rGO aerogel loaded with petal-shaped SnS2, that is, three-dimensional ordered parallel lamellar structure C / rGO / SnS2 aerogel.

[0050] The XRD patterns of the parallel sheet structure C / rGO and the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogels prepared in this example are shown in Figure 2. Figure 1 As shown, compared with C / rGO, the diffraction peaks corresponding to the (001), (100), (101) and (110) crystal planes of SnS2 in the XRD of C / rGO / SnS2 aerogel are clearly observed, indicating that C / rGO / SnS2 aerogel is successfully prepared. Figure 2 The SEM image of C / rGO / SnS2 aerogel is shown in Figure 2. Figure 2 (a) It can be seen that the aerogel exhibits a parallel layer structure. Figure 2 (b) It can be seen that these flakes are loaded with petal-shaped SnS2.

[0051] (3) Preparation of absorbing materials

[0052] Silica gel and curing agent with a mass ratio of 100:1 were uniformly stirred in a beaker, and then the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel obtained in step (2) was immersed in the above mixture under vacuum assistance. The fully filled sample was then cured in an oven at 70°C for 3 hours to obtain an absorbing material.

[0053] The absorbing material was cut along the parallel lamellar direction for absorbing performance testing. The results showed that the organic matrix filling amount in the petal-shaped SnS2 parallel lamellar structure aerogel was 6.7wt%. The reflection loss curve of the absorbing material prepared in this example is shown in FIG. Figure 3 As shown, when the thickness is 1.45 mm, the effective absorption bandwidth of the absorbing material of this embodiment is 5.4 GHz, and the strongest absorption is -59.2 dB.

[0054] Example 2

[0055] The preparation method of the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel and the absorbing material in this embodiment is as follows:

[0056] (1) Preparation of parallel layer structure C / rGO aerogel

[0057] 2.4 g of chitosan was dissolved in acetic acid solution (2.4 mL of acetic acid was dissolved in 80 mL of deionized water) and stirred thoroughly to obtain a chitosan solution; 0.36 g of graphene oxide was dispersed in 40 mL of deionized water and ultrasonically treated at 500 W for 30 min to prepare a 9 mg / mL graphene oxide suspension; the chitosan solution and the graphene oxide suspension were mixed and stirred at a speed of 400 r / min for 120 min to obtain a uniform chitosan / graphene oxide precursor solution, which was then poured into a circular mold, placed on a copper platform in a container filled with liquid nitrogen, and bidirectionally frozen. After freezing, the mixture was freeze-dried in a freeze dryer for 60 h to obtain a chitosan / graphene oxide aerogel with a parallel lamellar structure;

[0058] The obtained chitosan / graphene oxide aerogel was placed in a tubular furnace and heated to 500°C at a heating rate of 2°C / min under an argon atmosphere, kept warm for 1 hour, and then heated to 800°C at a heating rate of 5°C / min and kept warm for 2 hours to obtain C / rGO aerogel.

[0059] (2) Petal-shaped SnS2 loaded on parallel lamellar C / rGO aerogel

[0060] 0.4348 g of tin tetrachloride was dispersed in 50 mL of ethanol and stirred for 60 min to obtain solution A. 50 mg of parallel lamellar structure C / rGO aerogel was immersed in solution A, and 0.27 g of thioacetamide was added and stirred evenly. The solution was heated to 48 ° C and maintained for 3 h. Then, it was placed at room temperature for 24 h. The precipitate was collected and washed with ethanol three times. The precipitate was dried in an oven at 40 ° C overnight to obtain C / rGO aerogel loaded with petal-shaped SnS2, that is, three-dimensional ordered parallel lamellar structure C / rGO / SnS2 aerogel.

[0061] (3) Preparation of absorbing materials

[0062] Silica gel and curing agent with a mass ratio of 100:1 were uniformly stirred in a beaker, and then the three-dimensional ordered parallel sheet structure C / rGO / SnS2 aerogel obtained in step (2) was immersed in the above mixture under vacuum assistance. The fully filled sample was then cured in an oven at 70°C for 3 hours to obtain an absorbing material.

[0063] The absorbing material was cut along the parallel lamellar direction for absorbing performance testing. The results showed that the organic matrix filling amount in the petal-shaped SnS2 parallel lamellar structure aerogel was 6.7wt%. The reflection loss curve of the absorbing material prepared in this example is shown in FIG. Figure 4 As shown, when the thickness is 1.75 mm, the effective absorption bandwidth of the absorbing material of this embodiment is 3.3 GHz, and the strongest absorption is -15.8 dB.

[0064] Comparative Example 1

[0065] Silica gel and curing agent in a mass ratio of 100:1 were uniformly stirred in a beaker, and then the C / rGO aerogel obtained in step (1) of Example 1 was immersed in the above mixture under vacuum assistance. The fully filled sample was then cured in an oven at 70°C for 3 hours to obtain a porous absorbing material.

[0066] The absorbing material is cut along the direction parallel to the sheet layer for absorbing performance test. Its reflection loss curve is as follows Figure 5 As shown in FIG. 1 , at a thickness of 1.45 mm, the effective absorption bandwidth of the absorbing material prepared in this embodiment is 0 GHz, and the maximum absorption is -8.6 dB. Comparing the performance of the absorbing material prepared in Example 1 with that of the absorbing material prepared in Example 1, it is shown that the absorbing material in Example 1 has better performance.

[0067] Comparative Example 2

[0068] Disperse 0.3261 g of tin tetrachloride and 0.2025 g of thioacetamide in 50 mL of ethanol, stir for 60 min to obtain solution A, heat to 48 ° C, maintain for 3 h, then place at room temperature for 24 h, centrifuge, wash with ethanol three times, and dry in a 40 ° C oven overnight to obtain pure SnS2.

[0069] The silica gel and curing agent with a mass ratio of 100:1 were uniformly stirred in a beaker, filled with 6.7wt% SnS2, and cured in a 70℃ oven for 3h. The samples were cut into rings for testing and calculation of the absorbing performance. The reflection loss curve of the absorbing material prepared in this embodiment is shown in FIG. Figure 6 As shown, at a thickness of 1.45 mm, the effective absorption bandwidth of the absorbing material of this comparative example is 0 GHz, and the maximum absorption is -2.0 dB. Comparison with the performance of the absorbing material prepared in Example 1 shows that the absorbing material of Example 1 has better performance.

[0070] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional ordered parallel sheet structure aerogel, characterized in that: The following steps are involved: (1) Carbonizing chitosan / graphene oxide aerogel to obtain parallel lamellar carbon / reduced graphene oxide aerogel, wherein the preparation method of the chitosan / graphene oxide aerogel is as follows: uniformly mixing a chitosan solution and a graphene oxide suspension to obtain a chitosan / graphene oxide precursor solution, and performing bidirectional freezing and freeze-drying on the chitosan / graphene oxide precursor solution to obtain the chitosan / graphene oxide aerogel; the bidirectional freezing is as follows: transferring the chitosan / graphene oxide precursor solution to a cold casting mold and freezing it at a temperature of -10 to -196°C for 30 to 180 minutes; (2) Petal-shaped SnS2 is loaded onto a parallel lamellar carbon / reduced graphene oxide aerogel to obtain a three-dimensional ordered parallel lamellar aerogel; wherein the method for loading petal-shaped SnS2 onto a parallel lamellar carbon / reduced graphene oxide aerogel is as follows: immersing the parallel lamellar carbon / reduced graphene oxide aerogel into a tin salt solution, adding a sulfur-containing compound, heating, and standing at room temperature, collecting the precipitate for washing and drying.

2. The preparation method according to claim 1, characterized in that The concentration of the chitosan solution is 5-50 mg / mL, the concentration of the graphene oxide suspension is 2-30 mg / mL, and the mass ratio of the chitosan solution to the graphene oxide suspension is 1:0.1-2.

3. The preparation method according to claim 1, characterized in that The bidirectional freezing comprises: transferring the chitosan / graphene oxide precursor solution into a cold casting mold and freezing it at a temperature of -10 to -196°C for 30 to 180 minutes; and the freeze drying comprises: freeze drying the bidirectionally frozen chitosan / graphene oxide precursor solution at a temperature of -40 to 35°C for 48 to 72 hours.

4. The preparation method according to claim 1, characterized in that In step (1), the carbonization conditions are: heating to 300-1000°C at a heating rate of 1-10°C / min under an inert atmosphere, and keeping the temperature for 1-10 h.

5. The preparation method according to claim 1, characterized in that The tin salt in the tin salt solution is one of tin nitrate, tin sulfate or tin chloride, the solvent is one of deionized water, anhydrous ethanol or ethylene glycol, and the concentration of the tin salt solution is 0.1-20.0 g / L; the sulfur-containing compound is one of thiourea or thioacetamide; the mass ratio of the parallel sheet structure carbon / reduced graphene oxide aerogel to the tin salt is 1:1-1:20, and the mass ratio of the sulfur-containing compound to the tin salt is 2:1-1:

2.

6. A three-dimensional ordered parallel sheet structure aerogel prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the three-dimensional ordered parallel sheet structure aerogel according to claim 6 in the field of wave absorption.

8. A wave absorbing material prepared by filling an organic matrix with the three-dimensional ordered parallel lamellar structure aerogel according to claim 6 using a vacuum impregnation method.

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