Preparation method of MXene aerogel and MXene aerogel

Abstract

The invention relates to a preparation method of MXene aerogel and the MXene aerogel. The preparation method of the MXene aerogel comprises the following steps: preparing a sodium alginate solution; a CaCl2 solution is added into the sodium alginate solution, standing is carried out, first gel is obtained, and the mass ratio of the CaCl2 solution to the sodium alginate solution ranges from 2: 100 to 5: 100; performing solvent replacement on the first gel by using absolute ethyl alcohol to obtain second gel; performing freeze drying on the second gel to obtain first aerogel; the first aerogel is soaked in an MXene dispersion liquid, and a first substance is formed; and drying the first substance to obtain the MXene aerogel. The MXene aerogel prepared by the method has excellent electromagnetic shielding performance and good infrared stealth performance.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of stealth material, in particular to a preparation method of MXene aerogel and the MXene aerogel. BACKGROUND

[0002] In recent years, with the wide application and continuous progress of electromagnetic wave and infrared detection technology in the fields of environmental monitoring, industrial detection, security protection, etc., the sensing sensitivity of related equipment to electromagnetic radiation and infrared thermal radiation has been significantly improved. While this technological progress brings many conveniences, it also puts forward higher requirements for the electromagnetic shielding and infrared stealth performance of equipment in specific application scenarios. Therefore, developing materials with electromagnetic shielding and infrared stealth performance is crucial for improving the adaptability and reliability of equipment in complex electromagnetic and thermal environments. SUMMARY

[0003] In view of the above problems, the embodiment of the present application provides a preparation method of MXene aerogel and the MXene aerogel, which overcomes the above problems or at least partially solves the above problems.

[0004] According to an aspect of the embodiment of the present application, a preparation method of MXene aerogel is provided, comprising: preparing a sodium alginate solution; adding a CaCl2 solution to the sodium alginate solution to obtain a first gel by standing, the mass ratio of the CaCl2 solution to the sodium alginate solution being 2:100 to 5:100; freeze-drying the second gel to obtain a first aerogel; immersing the first aerogel in a MXene dispersion liquid to form a first substance; and drying the first substance to obtain the MXene aerogel.

[0005] In an optional manner, the method for preparing the sodium alginate solution comprises: dissolving sodium alginate powder in deionized water to obtain a first solution, wherein the content of the sodium alginate powder in the first solution is 2wt% to 5wt%; and dissolving hydroxyethyl cellulose powder in the first solution to obtain the sodium alginate solution, the mass ratio of the hydroxyethyl cellulose powder to the sodium alginate powder being 1:10.

[0006] In an optional manner, the method for dissolving the sodium alginate powder in the deionized water to obtain the first solution comprises: placing the sodium alginate powder in the deionized water, heating at 60°C, and stirring at a stirring speed of 500 rpm for 30 min to obtain the first solution.

[0007] In an alternative manner, the method for dissolving the hydroxyethyl cellulose powder in the first solution to obtain the sodium alginate solution comprises: placing the hydroxyethyl cellulose powder in the first solution, heating at 60 DEG C, stirring at a stirring speed of 500 rpm for 10 min to obtain the sodium alginate solution.

[0008] In an alternative manner, the standing time of the first gel obtained by adding the CaCl2 solution in the sodium alginate solution is 3 h.

[0009] In an alternative manner, the method for freeze-drying the second gel to obtain the first aerogel comprises: freeze-drying the second gel in a freeze-drying machine at -40 DEG C to obtain the first aerogel.

[0010] In an alternative manner, the freeze-drying time is 24 h.

[0011] In an alternative manner, the method for preparing the MXene dispersion liquid comprises: dispersing MXene powder in deionized water to obtain a MXene dispersion liquid, and the content of the MXene powder in the MXene dispersion liquid is 2wt% to 5wt%.

[0012] In an alternative manner, the method for drying the first substance to obtain the MXene aerogel comprises: placing the first substance in a vacuum oven to dry to obtain the MXene aerogel.

[0013] According to another aspect of the embodiments of the present application, a MXene aerogel is provided, which is prepared by the above-mentioned method for preparing a MXene aerogel.

[0014] The beneficial effects of the embodiments of the present application include providing a method for preparing a MXene aerogel, which comprises: preparing a sodium alginate solution; adding a CaCl2 solution in the sodium alginate solution to obtain a first gel, and the mass ratio of the CaCl2 solution to the sodium alginate solution is 2:100 to 5:100; using anhydrous ethanol to perform solvent replacement on the first gel to obtain a second gel; freeze-drying the second gel to obtain a first aerogel; immersing the first aerogel in a MXene dispersion liquid to form a first substance; and drying the first substance to obtain the MXene aerogel. The MXene aerogel prepared by the method has excellent electromagnetic shielding performance and good infrared stealth performance. BRIEF DESCRIPTION OF DRAWINGS

[0015] One or more embodiments are illustrated by way of example in the drawings in which like reference numerals indicate like elements, and in which: the drawings are not necessarily to scale, unless specifically stated, and in which

[0016] Figure 1 is a flowchart of a method for preparing MXene aerogel provided by an embodiment of the application. Figure 2 is a flowchart of a method for preparing a sodium alginate solution provided by an embodiment of the application. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0018] An embodiment of the present application provides a method for preparing MXene aerogel, please refer to Figure 1 , which comprises the following steps: Step S10, preparing sodium alginate.

[0019] In some embodiments, please refer to Figure 2 , the method for preparing a sodium alginate solution comprises: Step S11, dissolving sodium alginate powder in deionized water to obtain a first solution, wherein the content of the sodium alginate powder in the first solution is 2wt% to 5wt%.

[0020] Wherein, the sodium alginate powder is a polysaccharide sodium salt, and the important characteristic of sodium alginate is that it can be ionically cross-linked with calcium ions to form a gel.

[0021] Wherein, the deionized water is high-purity water purified by ion exchange resin.

[0022] The content of the sodium alginate powder in the first solution is 2wt% to 5wt%, for example, 2g to 5g of sodium alginate powder is dissolved in 100g of the first solution.

[0023] In some embodiments, the method for dissolving sodium alginate powder in deionized water to obtain a first solution comprises: placing the sodium alginate powder in deionized water, keeping heating at 60°C, stirring at a stirring speed of 500 rpm for 30 min to obtain the first solution.

[0024] Step S12, dissolving hydroxyethyl cellulose powder in the first solution to obtain the sodium alginate solution, the mass ratio of the hydroxyethyl cellulose powder to the sodium alginate powder is 1:10.

[0025] The mass ratio of the hydroxyethyl cellulose powder to the sodium alginate powder is 1:10, for example, the mass of the sodium alginate powder is 5g, and the mass of the hydroxyethyl cellulose powder is 0.5g. Alternatively, for example, the mass of the sodium alginate powder is 2g, and the mass of the hydroxyethyl cellulose powder is 0.2g.

[0026] It is worth noting that in some embodiments, the method of dissolving hydroxyethyl cellulose powder in the first solution to obtain the sodium alginate solution comprises: The hydroxyethyl cellulose powder is placed in the first solution and heated at 60°C, and stirred at a stirring speed of 500 rpm for 10 min to obtain the sodium alginate solution.

[0027] The addition of hydroxyethyl cellulose powder can improve the mechanical strength of the finally formed MXene aerogel.

[0028] It is worth noting that in some embodiments, after the sodium alginate solution is prepared, cooling treatment is required, the temperature is reduced to room temperature, and the sodium alginate solution is left to stand at room temperature, for example, for 3h, to improve the stability and uniformity of the sodium alginate solution.

[0029] Step S20, adding a CaCl2 solution to the sodium alginate solution to obtain a first gel, the mass ratio of the CaCl2 solution to the sodium alginate solution is 2:100 to 5:100.

[0030] In some embodiments, the standing time of the first gel obtained by adding the CaCl2 solution to the sodium alginate solution is 3h.

[0031] The CaCl2 solution can be added to the sodium alginate solution in a dropwise manner.

[0032] During the standing process, the first gel is gradually gelled.

[0033] Step S30, using anhydrous ethanol to replace the solvent of the first gel to obtain a second gel.

[0034] Using anhydrous ethanol to replace the solvent of the first gel means that the first gel is soaked in anhydrous ethanol for 24h to obtain the second gel. During the soaking process, the anhydrous ethanol can be replaced several times to ensure complete solvent replacement and improve the purity and mechanical properties of the second gel.

[0035] The anhydrous ethanol refers to ethanol with a purity of 99.5% or above and without water.

[0036] Step S40, freeze-drying the second gel to obtain a first aerogel.

[0037] In some embodiments, the method of freeze-drying the second gel to obtain a first aerogel comprises: The second gel is placed in a freeze dryer at -40℃ for freeze-drying to obtain the first aerogel. The freeze-drying time is 24h.

[0038] Step S50, immersing the first aerogel in a MXene dispersion liquid to form a first substance.

[0039] The time for immersing the first aerogel can be set according to actual needs, for example, 30min or 20min or 40min, to ensure that the MXene dispersion liquid is fully penetrated. The first substance is a composite material immersed in the MXene dispersion liquid.

[0040] It is worth noting that in some embodiments, the preparation method of the MXene dispersion liquid is: dispersing MXene powder in deionized water to obtain a MXene dispersion liquid, and the content of the MXene powder in the MXene dispersion liquid is 2wt% to 5wt%.

[0041] In some embodiments, the MXene powder is dispersed in deionized water for 10min under ultrasonic dispersion.

[0042] The MXene powder has high electrical conductivity, large specific surface area and good hydrophilicity, making it have wide application prospects in the fields of energy storage, catalysis, sensing and biomedical engineering. 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. The MXene can be Ti3C2T x nanomaterial.

[0043] It is worth noting that the MXene is in a sheet shape. The sheet structure of MXene helps it to reflect electromagnetic waves multiple times in the MXene aerogel and then convert the electromagnetic waves into heat energy to be absorbed, so as to improve the electromagnetic shielding performance of the finally formed MXene aerogel.

[0044] Step S60, drying the first substance to obtain the MXene aerogel.

[0045] It is worth noting that in some embodiments, the method for drying the first substance to obtain the MXene aerogel comprises: drying the first substance in a vacuum oven to obtain the MXene aerogel. The specific drying temperature and drying time can be selected according to actual needs. For example, the drying temperature is 60°C, and the drying time is 12h; or, for example, the drying temperature is 80°C, and the drying time is 5h.

[0046] The embodiment of the present application provides a preparation method of a MXene aerogel, which comprises the following steps: preparing a sodium alginate solution; adding a CaCl2 solution into the sodium alginate solution to obtain a first gel by standing, wherein the mass ratio of the CaCl2 solution to the sodium alginate solution is 2:100 to 5:100; performing solvent replacement on the first gel by using anhydrous ethanol to obtain a second gel; freeze-drying the second gel to obtain a first aerogel; immersing the first aerogel in a MXene dispersion liquid to form a first substance; and drying the first substance to obtain the MXene aerogel. The MXene aerogel prepared by the method has excellent electromagnetic shielding performance and good infrared stealth performance.

[0047] The embodiment of the present application further provides a MXene aerogel, which is prepared by using the preparation method of the MXene aerogel in the above embodiment.

[0048] In order to facilitate the reader to understand the inventive concept of the embodiments of the present application, the technical effects of using the embodiments of the present application are demonstrated as follows.

[0049] Embodiment one <Preparation of a sodium alginate solution> 5g of sodium alginate powder is dissolved in 95g of deionized water, the heating temperature is kept at 60°C, and mechanical stirring is performed at a stirring speed of 500rpm for 30min to obtain a first solution. 0.5g of hydroxyethyl cellulose powder is added into the first solution to improve the mechanical strength, and stirring is performed at a stirring speed of 500rpm for 10min while keeping the temperature at 60°C.

[0050] <Preparation of a first gel> 5g of CaCl2 solution is added dropwise into 100g of the sodium alginate solution. solution, Crosslinking is gradually induced by diffusion, and the first gel is formed after standing for 3h for gradual gelation after the dropwise addition is completed.

[0051] <Preparation of a second gel> The first gel is soaked in anhydrous ethanol for 24h to perform solvent replacement, and a second gel is obtained.

[0052] <Preparation of a first aerogel> The second gel is placed in a freeze dryer at -40°C and freeze dried for 24h to form a first aerogel with a porous structure.

[0053] <Preparation of the first substance> 2g of MXene powder is dispersed in 98g of deionized water and ultrasonic dispersed for 10min to obtain a MXene dispersion. The first aerogel is immersed in the MXene dispersion and taken out after 30min to form the first substance.

[0054] <Preparation of the MXene aerogel> The first substance is placed in a vacuum oven to dry to obtain the MXene aerogel, the drying temperature is 80°C, and the drying time is 5h.

[0055] <Performance test> The electromagnetic shielding material is tested for shielding performance in the X-band (8.2~12.4GHz) using an Agilent vector network analyzer, and the infrared emissivity is tested using an IR-2 dual-band infrared emissivity instrument. The test results are shown in Table 1.

[0056] Example Two <Preparation of a sodium alginate solution> 2g of sodium alginate powder is dissolved in 98g of deionized water, heated to a temperature of 60°C, and mechanically stirred at a stirring speed of 500rpm for 30min to obtain a first solution. 0.2g of hydroxyethyl cellulose powder is added to the first solution to improve the mechanical strength, and stirred at a stirring speed of 500rpm for 10min while maintaining a temperature of 60°C.

[0057] <Preparation of a first gel> 2g of calcium chloride solution is added dropwise to 100g of the sodium alginate solution. solution, The crosslinking is gradually initiated by diffusion, and the first gel is formed after standing for 3h after the dropwise addition is completed.

[0058] <Preparation of a second gel> The same as Example One.

[0059] <Preparation of a first aerogel> The same as Example One.

[0060] <Preparation of a first substance> 5g of MXene powder is dispersed in 95g of deionized water and ultrasonic dispersed for 10min to obtain a MXene dispersion. The first aerogel is immersed in the MXene dispersion and taken out after 30min to form the first substance.

[0061] <Preparation of a MXene aerogel> The same as Example One.

[0062] <Performance test> The same as example one.

[0063] Table 1

[0064] From Table 1, the electromagnetic shielding effectiveness refers to the attenuation ability of the material to electromagnetic waves, and the higher the value, the better the shielding effect. The infrared emissivity reflects the thermal radiation characteristics of the material, and low infrared emissivity indicates good infrared stealth performance. The electromagnetic shielding effectiveness of the MXene aerogel of example one is 58.3 dB, indicating that it has excellent electromagnetic shielding performance. The electromagnetic shielding effectiveness of the MXene aerogel of example two is 62.5 dB, also indicating that it has excellent electromagnetic shielding performance. In addition, the infrared emissivity of example one is 0.275 Hz, showing good infrared stealth effect; and that of example two is 0.218 Hz, also showing excellent infrared stealth characteristics.

[0065] It should be noted that the preparation method of the MXene aerogel proposed in the present application uses sodium alginate as raw material to obtain a good aerogel structure through crosslinking, gelation, displacement, freeze-drying and other means. Finally, the first aerogel formed is immersed in a MXene dispersion liquid to obtain a MXene aerogel. The porous structure of the composite MXene aerogel can effectively reduce impedance mismatch, and the sheet-shaped MXene with high conductivity can reflect electromagnetic waves multiple times inside the aerogel and then convert the electromagnetic waves into heat energy to absorb. It is worth noting that the low infrared reflectivity of MXene provides excellent infrared stealth performance for the MXene aerogel, and provides a new idea for the research and development of stealth materials.

[0066] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; under the idea of the present application, the technical features in the above examples or different examples can also be combined, and the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be simple, they are not provided in details; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing MXene aerogel, characterized in that, include: Preparation of sodium alginate solution; Add CaCl2 solution to the sodium alginate solution and let it stand to obtain a first gel. The mass ratio of CaCl2 solution to sodium alginate solution is 2:100 to 5:

100. The first gel was solvent-displaced using anhydrous ethanol to obtain a second gel. The second gel was freeze-dried to obtain the first aerogel; The first aerogel is impregnated with MXene dispersion to form the first substance; The first substance was dried to obtain the MXene aerogel.

2. The method for preparing MXene aerogel according to claim 1, characterized in that, The method for preparing sodium alginate solution includes: Sodium alginate powder is dissolved in deionized water to obtain a first solution, wherein the content of sodium alginate powder in the first solution is 2 wt% to 5 wt%. Hydroxyethyl cellulose powder is dissolved in the first solution to obtain the sodium alginate solution, wherein the mass ratio of hydroxyethyl cellulose powder to sodium alginate powder is 1:

10.

3. The method for preparing MXene aerogel according to claim 2, characterized in that, The method for dissolving sodium alginate powder in deionized water to obtain a first solution includes: The sodium alginate powder was placed in deionized water and heated at 60°C. The mixture was stirred at 500 rpm for 30 minutes to obtain the first solution.

4. The method for preparing MXene aerogel according to claim 2, characterized in that, The method of dissolving hydroxyethyl cellulose powder in the first solution to obtain the sodium alginate solution includes: The hydroxyethyl cellulose powder was placed in the first solution, heated to 60°C, and stirred at 500 rpm for 10 minutes to obtain the sodium alginate solution.

5. The method for preparing MXene aerogel according to claim 1, characterized in that, The first gel is obtained by adding CaCl2 solution to the sodium alginate solution and allowing it to stand for 3 hours.

6. The method for preparing MXene aerogel according to claim 1, characterized in that, The method for freeze-drying the second gel to obtain the first aerogel includes: The second gel was freeze-dried in a freeze dryer at -40°C to obtain the first aerogel.

7. The method for preparing MXene aerogel according to claim 6, characterized in that, The freeze-drying time is 24 hours.

8. The method for preparing MXene aerogel according to claim 1, characterized in that, The MXene dispersion is prepared by dispersing MXene powder in deionized water to obtain an MXene dispersion, wherein the content of MXene powder in the MXene dispersion is 2wt% to 5wt%.

9. A method for preparing an MXene aerogel according to any one of claims 1-8, characterized in that, The method for drying the first substance to obtain the MXene aerogel includes: placing the first substance in a vacuum oven to dry it to obtain the MXene aerogel.

10. An MXene aerogel, characterized in that, The MXene aerogel is prepared using the method for preparing MXene aerogel as described in any one of claims 1-9.

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