Modified graphene aerogel wave-absorbing material as well as preparation method and application thereof

Abstract

The invention discloses a modified graphene aerogel wave-absorbing material and a preparation method and application thereof.The preparation method comprises the following steps that ethyl alcohol, ZnSnO3 and 3-aminopropyltriethoxysilane are added into dispersion liquid of graphene oxide, then hydro-thermal treatment is conducted, a product obtained after hydro-thermal treatment is frozen, then freeze drying is conducted, and the modified graphene aerogel wave-absorbing material is obtained. And finally, calcining the product in an inert atmosphere to obtain the modified graphene aerogel wave-absorbing material. According to the present invention, graphene is modified by using 3-aminopropyltriethoxysilane and ethanol together and ZnSnO3 is loaded, the prepared ZnSnO3-loaded reduced graphene oxide has characteristics of high absorption strength, wide absorption frequency band, thin matching thickness, light weight, strong heat insulation ability and the like, and the preparation method has characteristics of simpleness, easy performing, low cost and great industrial application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorbing materials, and in particular relates to a modified graphene aerogel absorbing material and a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In recent years, with the rapid development of electronic information technology, the penetration rate of various electronic devices (such as smartphones, computers, and wireless communication devices) has rapidly increased. These devices generate a large amount of electromagnetic waves during operation, leading to increasingly serious electromagnetic pollution. Electromagnetic waves not only interfere with the normal operation of electronic devices but also pose potential risks to human health. Therefore, the development of high-performance electromagnetic wave absorbing materials to effectively suppress electromagnetic interference has become a key research direction in materials science.

[0004] Electromagnetic wave absorbing materials are mainly divided into two categories based on their loss mechanisms: magnetic absorbing materials and dielectric absorbing materials. Reduced graphene oxide (rGO), a typical dielectric absorbing material, has attracted widespread attention in the field of absorbing materials due to its high specific surface area, excellent conductivity, and light weight. However, existing rGO-based absorbing materials still have the following technical issues: Poor impedance matching performance: rGO has a high dielectric constant, which leads to strong reflection of electromagnetic waves on the surface of the material, making it difficult to achieve efficient absorption.

[0005] Narrow effective absorption bandwidth: The single dielectric loss mechanism limits the material's absorption performance over a wide frequency range.

[0006] Graphene sheets are prone to agglomeration: rGO sheets are easily stacked due to van der Waals forces, which affects the formation of its three-dimensional porous structure and thus reduces the multiple scattering and absorption efficiency of electromagnetic waves.

[0007] To address the above problems, the following improvement measures are generally adopted in the prior art: Introducing magnetic components (such as Fe3O4, Co, etc.) to enhance magnetic loss and improve impedance matching; Constructing three-dimensional porous structures (such as aerogels and foams) to reduce graphene agglomeration and improve electromagnetic wave loss capacity; Compounding with other nanomaterials (such as carbon nanotubes, conductive polymers, etc.) to optimize dielectric properties and broaden the absorption band.

[0008] However, existing technologies still find it difficult to achieve the comprehensive performance requirements of broadband, strong absorption, and thin thickness while maintaining the lightweight characteristics of the material. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a modified graphene aerogel absorbing material, a preparation method and application thereof, wherein graphene is modified with 3-aminopropyltriethoxysilane and ethanol and loaded with ZnSnO3. The prepared ZnSnO3-loaded reduced graphene oxide has the characteristics of high absorption intensity, wide absorption bandwidth, thin matching thickness, light weight, strong thermal insulation ability, etc. At the same time, the preparation method of the present invention is simple and easy, low cost, and has great prospects for industrial application.

[0010] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a method for preparing a modified graphene aerogel absorbing material, comprising the following steps: Adding ethanol, ZnSnO3 and 3-aminopropyltriethoxysilane (APTES) to a dispersion of graphene oxide and then performing a hydrothermal treatment; freezing the hydrothermally treated product in liquid nitrogen, freeze-drying it, and finally calcining the product in an inert atmosphere to obtain a modified graphene aerogel absorbing material; Among them, the mass ratio of graphene oxide to ZnSnO3 is 1:0.5-5; The volume ratio of the graphene oxide dispersion, ethanol and APTES is 600:50-700:1-10.

[0011] The mass ratio of graphene oxide to ZnSnO3 can be 1:0.5, 1:1, 1:2, 1:3, 1:4 or 1:5.

[0012] During the hydrothermal treatment, graphene oxide was reduced to reduced graphene oxide, and APTES underwent hydrolysis and condensation and coupled with graphene oxide.

[0013] The product after hydrothermal treatment is frozen in liquid nitrogen to shorten the freeze-drying cycle and reduce damage to the internal structure of the material.

[0014] In some embodiments, the concentration of graphene oxide in the graphene oxide dispersion is 1-10 mg / ml, such as 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, 6 mg / ml, 7 mg / ml, 8 mg / ml, 9 mg / ml, or 10 mg / ml.

[0015] In some embodiments, the hydrothermal treatment temperature is 100-200° C., and the hydrothermal treatment time is 8-16 hours. For example, the hydrothermal treatment temperature can be 100° C., 110° C., 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., or 200° C., and the hydrothermal treatment time is 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or 16 hours.

[0016] In some embodiments, the freezing is performed in liquid nitrogen.

[0017] In some embodiments, the freeze-drying temperature is -10 to -55°C, and the freeze-drying time is 12 to 48 hours.

[0018] In some embodiments, the calcination temperature is 400-700°C, and the calcination time is 1-5 hours. For example, the calcination temperature can be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, and 700°C; and the calcination time can be 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0019] In some embodiments, a ZnSnO3 preparation method comprises dispersing a soluble tin salt, sodium dodecylbenzenesulfonate, and a soluble zinc salt in water, adding sodium hydroxide, washing the resulting precipitate alternately with water and ethanol, and drying to obtain ZnSnO3 powder. Sodium dodecylbenzenesulfonate acts as a dispersant to improve the dispersibility of the ZnSnO3 nanoparticles and prevent agglomeration of the precipitated particles. During the washing process, water dissolves and removes surface-adsorbed impurity ions, while ethanol prevents agglomeration of the precipitate while removing moisture and accelerating drying.

[0020] Preferably, the soluble tin salt is SnCl4·5H2O; The soluble zinc salt is zinc acetate, zinc nitrate, zinc sulfate or zinc chloride.

[0021] In a second aspect, the present invention provides a modified graphene aerogel absorbing material prepared by the preparation method.

[0022] The modified graphene aerogel absorbing material has a three-dimensional porous layered structure, is composed of graphene and ZnSnO3 nanoparticles, and is modified with APTES and ethanol.

[0023] In a third aspect, the present invention provides an application of the modified graphene aerogel absorbing material in preparing an electromagnetic wave absorber.

[0024] In some embodiments, the electromagnetic wave absorber includes the modified graphene aerogel absorbing material and paraffin, and the mass ratio of the modified graphene aerogel absorbing material to the paraffin is 1:7-10.

[0025] The absorber has a matching thickness of 3.66 mm, reaches a maximum absorption intensity at a frequency of 11.44 GHz, and has a reflection loss of -70 dB.

[0026] When the absorber has a single matching thickness of 4.39 mm, the effective absorption bandwidth is 5.84 GHz. The effective absorption bandwidth means that the electromagnetic wave absorption RL is less than -10 dB, that is, 90% of the electromagnetic waves are absorbed.

[0027] The beneficial effects achieved by one or more embodiments of the present invention are as follows: (1) In the present invention, the addition of ZnSnO3 nanoparticles introduces dielectric loss, improving impedance matching performance. The uniform distribution of the nanoparticles increases the contact area between the particles and rGO, enhancing interfacial polarization and thus improving electromagnetic wave absorption performance. The addition of ethanol inhibits the agglomeration of graphene sheets, thereby increasing the number of suspended oxygen bonds and exposed defects, which is conducive to enhancing polarization reactions.

[0028] (2) The addition of APTES enhances the structural stability of graphene in ethanol and controls the excessive expansion of the graphene pore structure; and the addition of APTES introduces amino groups on the surface of reduced graphene oxide, which is beneficial to enhance the polarization reaction.

[0029] (3) ZnSnO3-rGO electromagnetic wave absorber modified by APTES and ethanol has excellent electromagnetic wave absorption performance, RL min It is -70 dB at 11.44 GHz, and the effective absorption bandwidth is 5.84 GHz when the thickness is 4.39 mm.

[0030] The ZnSnO3-rGO absorbing material modified with APTES and ethanol of the present invention has a lower filling amount and higher reflection loss than the ZnSnO3-rGO sample modified with only ethanol. The filling rate of the electromagnetic wave absorber is only 10-20%, which is much lower than the filling rate of electromagnetic wave absorbers filled with other carbon materials, meeting the requirement of light weight of electromagnetic wave absorbing materials.

[0031] (4) The ZnSnO3-rGO aerogel material of the present invention also has good thermal insulation, photothermal conversion and other properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1This is the XRD pattern of the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel prepared in Example 1 of the present invention.

[0034] Figure 2 This is an SEM image of the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel prepared in Example 1 of the present invention.

[0035] Figure 3 This is an SEM image of ZnSnO3 nanoparticles in the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel prepared in Example 1 of the present invention. The ZnSnO3 micron particles are self-assembled from nanoparticles with a diameter of less than 50 nm.

[0036] Figure 4 In the figure, (a) is the dielectric constant of the APTES / ethanol co-modified ZnSnO3 loaded reduced graphene oxide aerogel prepared in Example 1, and (b) is the magnetic permeability.

[0037] Figure 5 This is a reflection loss diagram of the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel absorber prepared in Example 1 of the present invention.

[0038] Figure 6 This is a reflection loss diagram of the aerogel prepared in Comparative Example 1 of the present invention.

[0039] Figure 7 This is a reflection loss diagram of the aerogel prepared in Comparative Example 2 of the present invention.

[0040] Figure 8 This is a reflection loss diagram of the aerogel prepared in Comparative Example 3 of the present invention.

[0041] Figure 9 This is the infrared thermal image of the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel absorber of the present invention. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0043] The present invention will be further described below with reference to the embodiments.

[0044] Example 1 A method for preparing a modified graphene aerogel absorbing material comprises the following steps: 30 mg of ZnSnO3 was added to 30 ml of GO solution with a concentration of 2 mg / mL, followed by 30 mL of anhydrous ethanol and 50 μL of APTES. After stirring for 30 min, the mixture was ultrasonicated for 30 min. The mixture was then placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 180 °C. After 12 h of hydrothermal reaction, the product was frozen in liquid nitrogen and then freeze-dried.

[0045] The freeze-dried product was placed in a tube furnace and annealed at 550°C for 2 h at a heating rate of 5°C / min in a nitrogen atmosphere to obtain APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel.

[0046] Figure 1 This is the XRD pattern of the APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel prepared in Example 1, confirming that the prepared phase is ZnSnO3-rGO.

[0047] Figure 2 Figures a and b are SEM images of the APTES / ethanol co-modified ZnSnO3 loaded reduced graphene oxide aerogel finally obtained in Example 1, in which ZnSnO3 is dispersed in the three-dimensional pore walls and pores composed of graphene sheets.

[0048] Example 2 A method for preparing a modified graphene aerogel absorbing material comprises the following steps: To 30 mL of a 2 mg / mL GO solution, 30 mg of ZnSnO₃ was added, followed by 30 mL of anhydrous ethanol and 100 μL of APTES. After stirring for 30 minutes and ultrasonication for 30 minutes, the mixture was placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 180°C for 12 hours. The hydrothermal reaction system was frozen in liquid nitrogen and freeze-dried. The freeze-dried product was then annealed at 550°C for 2 hours in an argon atmosphere at a heating rate of 5°C / min to obtain an APTES / ethanol-modified ZnSnO₃-loaded reduced graphene oxide aerogel.

[0049] Example 3 A method for preparing a modified graphene aerogel absorbing material comprises the following steps: 30 mg ZnSnO3 was added to 30 ml of GO solution with a concentration of 2 mg / mL, and then 30 mL of anhydrous ethanol and 150 μL APTES were added. After stirring for 30 min, ultrasonic treatment was performed for 30 min, and then the mixed system was placed in a hydrothermal reactor for hydrothermal reaction at 180 °C. After the reaction for 12 h, the hydrothermal product was frozen in liquid nitrogen and then freeze-dried.

[0050] The freeze-dried product was placed in a tube furnace and annealed at 550 °C for 2 h at a heating rate of 5 °C / min in a nitrogen atmosphere to obtain APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel.

[0051] Example 4 A method for preparing a modified graphene aerogel absorbing material comprises the following steps: To a 30 mL 2 mg / mL GO solution, 30 mg ZnSnO₃ was added. Then, 30 mL of anhydrous ethanol and 200 μL APTES were added. The mixture was stirred for 30 minutes, ultrasonicated for 30 minutes, and then placed in a hydrothermal reactor for a hydrothermal reaction at 180°C for 12 hours. The hydrothermal reaction product was frozen in liquid nitrogen and freeze-dried. The freeze-dried product was annealed at 550°C for 2 hours in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min to obtain an APTES / ethanol co-modified ZnSnO₃-loaded reduced graphene oxide aerogel.

[0052] Comparative Example 1 A method for preparing an ethanol-modified ZnSnO3-loaded reduced graphene oxide aerogel electromagnetic wave absorbing material comprises the following steps: To a 30 mL (2 mg / mL) GO solution, 30 mg of ZnSnO₃ was added, followed by 30 mL of anhydrous ethanol. After stirring for 30 minutes and ultrasonication for 30 minutes, the mixture was placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 180°C for 12 hours. The product was then frozen in liquid nitrogen and freeze-dried. The freeze-dried product was then annealed at 550°C for 2 hours in a tube furnace under a nitrogen atmosphere at a heating rate of 5°C / min.

[0053] Comparative Example 2 A method for preparing an ethanol-modified ZnSnO3-loaded reduced graphene oxide aerogel electromagnetic wave absorbing material comprises the following steps: 30 mg of ZnSnO3 was added to 30 ml (2 mg / mL) of GO solution, followed by 30 mL of deionized water. After stirring for 30 min, ultrasonic treatment was performed for 30 min, and then the solution was placed in a hydrothermal reactor for a hydrothermal reaction at 180 °C. After the hydrothermal reaction lasted for 12 h, the product after the hydrothermal reaction was frozen in liquid nitrogen and freeze-dried. The product prepared by freeze-drying was then placed in a tube furnace and annealed at 550 °C for 2 h in a nitrogen atmosphere at a heating rate of 5 °C / min. The reflection loss diagram of the prepared electromagnetic wave absorbing material is shown in FIG. Figure 7 shown.

[0054] Comparative Example 3 30 mL of anhydrous ethanol was added to 30 mL (2 mg / mL) of GO solution; after stirring for 30 minutes, ultrasonic treatment was performed for 30 minutes, and then the solution was placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 180 °C. After the hydrothermal reaction for 12 hours, the product after the hydrothermal reaction was frozen in liquid nitrogen and freeze-dried. The product prepared by freeze-drying was then placed in a tube furnace and annealed at 550 °C for 2 hours at a heating rate of 5 °C / min in a nitrogen atmosphere. The reflection loss diagram of the prepared electromagnetic wave absorbing material is shown in FIG. Figure 8 shown.

[0055] Performance testing: (1) The APTE / ethanol co-modified ZnSnO3 loaded reduced graphene oxide aerogel electromagnetic wave absorbing material prepared in Example 1 was subjected to XRD test. The results are as follows: Figure 1 As shown in Figure 2, there is a weak broad peak at around 25°, corresponding to (002), which proves that rGO has been successfully reduced. The main diffraction peaks correspond to the (112) and (200) crystal planes of ZnSnO3 (JCPDS No. 28-1486). This indicates that ZnSnO3 still exists.

[0056] (2) The APTE / ethanol co-modified ZnSnO3 loaded reduced graphene oxide aerogel electromagnetic wave absorbing material prepared in Example 1 was observed under SEM and TEM. The results were as follows: Figure 2 and 3 As shown, it can be seen that ZnSnO3 is uniformly loaded in the graphene aerogel, and the cube-shaped nanoparticles shown by TEM are evenly distributed in the graphene flakes, confirming the existence of ZnSnO3.

[0057] (3) The APTE / ethanol co-modified ZnSnO3 loaded reduced graphene oxide aerogel electromagnetic wave absorbing material prepared in Example 1 was mixed with paraffin wax at a mass ratio of 1:9 and pressed into a ring-shaped absorber sample. The electromagnetic parameters were measured using an Agilent Technologies E8363A electromagnetic wave vector network analyzer. The electromagnetic wave absorption curve of the absorber was as follows: Figure 4 As shown, the absorption performance is determined by Figure 5 As shown, RL min It is -70 dB at 11.44 GHz, and the effective absorption bandwidth is 5.84 GHz when the thickness is 4.39 mm.

[0058] (4) The ethanol-modified ZnSnO3-loaded reduced graphene oxide aerogel electromagnetic wave absorbing material prepared in Example 1 was mixed with paraffin wax at a ratio of 1:9 and pressed into a ring-shaped absorber sample. The electromagnetic parameters were measured using an Agilent Technologies E8363A electromagnetic wave vector network analyzer. The absorption performance was obtained by Figure 6 It can be seen that the performance of Example 1 is much higher than that of the absorber of the experimental example, which proves that adding an appropriate amount of APTES can improve the electromagnetic wave absorption performance of ZnSnO3-rGO.

[0059] (5) The APTES / ethanol co-modified ZnSnO3-loaded reduced graphene oxide aerogel electromagnetic wave absorbing material (1 cm thick) prepared in Example 1 was placed on a heated substrate and heated at a constant temperature of 110°C. The specific temperature changes at different measurement points along the vertical direction were recorded by a computer over time. After 10 minutes, the temperature at the top of the aerogel remained at a level close to 36°C, showing excellent thermal insulation effect even at high temperatures. Figure 9 shown.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a modified graphene aerogel absorbing material, characterized in that: The steps include: Adding ethanol, ZnSnO3 and 3-aminopropyltriethoxysilane to a dispersion of graphene oxide, followed by hydrothermal treatment, freezing the hydrothermally treated product, freeze-drying it, and finally calcining the product in an inert atmosphere to obtain a modified graphene aerogel absorbing material; Among them, the mass ratio of graphene oxide to ZnSnO3 is 1:0.5-5; The volume ratio of the graphene oxide dispersion, ethanol and APTES is 600:50-700:1-10.

2. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: In the graphene oxide dispersion, the concentration of graphene oxide is 1-10 mg / ml.

3. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: The temperature of the hydrothermal treatment is 100-200° C., and the time of the hydrothermal treatment is 8-16 hours.

4. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: The freezing is performed in liquid nitrogen; Alternatively, the freeze-drying temperature is -10 ~ -55°C, and the freeze-drying time is 12-48h.

5. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: The calcination temperature is 400-700° C., and the calcination time is 1-5 hours.

6. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: The preparation method of ZnSnO3 is as follows: dispersing soluble tin salt, sodium dodecylbenzenesulfonate and soluble zinc salt in water, adding sodium hydroxide, washing the precipitate generated by the reaction alternately with water and ethanol, and drying to obtain ZnSnO3 powder.

7. The method for preparing the modified graphene aerogel absorbing material according to claim 1, wherein: The soluble tin salt is SnCl4·5H2O; The soluble zinc salt is zinc acetate, zinc nitrate, zinc sulfate or zinc chloride.

8. A modified graphene aerogel absorbing material, characterized by: Prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the modified graphene aerogel absorbing material according to claim 8 in the preparation of an electromagnetic wave absorber.

10. The use according to claim 9, characterized in that: The electromagnetic wave absorber comprises the modified graphene aerogel absorbing material and paraffin, and the mass ratio of the modified graphene aerogel absorbing material to the paraffin is 1:7-10.

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