Graphene / titanium dioxide composite low-frequency microwave absorbing material and preparation method thereof
By constructing a heterogeneous interface through graphene/titanium dioxide composite materials and regulating the size of titanium dioxide particles, the problems of thickness and stability of traditional microwave absorbing materials in the low frequency band are solved, and efficient low-frequency microwave absorption effect is achieved.
Patent Information
- Application Number
- CN202511090270.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-10-17
AI Technical Summary
Traditional microwave absorbing materials have problems in the low-frequency band, such as large thickness, heavy weight, difficult impedance matching, insufficient low-frequency loss and poor environmental stability. In addition, magnetic materials are easily demagnetized in high-temperature and high-corrosion environments, which limits their application.
By using graphene/titanium dioxide composite materials and constructing a heterogeneous interface, the edge selectivity of graphene and the surfactant of polyvinyl alcohol are utilized to regulate the size of titanium dioxide particles and optimize the low-frequency microwave absorption performance.
The prepared graphene/titanium dioxide composite material exhibits excellent microwave absorption performance in the low frequency band, with a reflection loss RL value of -52.13dB to -27.49dB, an electromagnetic wave frequency of 3.76-4.24GHz, and an absorption bandwidth of 1.46-1.88GHz, which solves the shortcomings of traditional materials.
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Figure CN120795513A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of nanocomposites, in particular to a graphene / titanium dioxide composite low-frequency microwave absorption material and a preparation method thereof. BACKGROUND
[0002] With the rapid development of microwave communication technologies such as 5G networks and the popularity of new electronic devices, the problems of microwave pollution and signal interference are increasingly prominent, which makes the research and development of high-performance microwave absorption materials more urgent. However, the traditional microwave absorption materials have problems such as large thickness, heavy quality, difficult impedance matching, insufficient low-frequency loss, poor environmental stability and the like in the low-frequency (S-band: 2-4 GHz, C-band: 4-8 GHz) range, which limits the further development and application of microwave absorption materials in the low-frequency range.
[0003] To solve the above problems, various low-frequency microwave absorption materials have been developed by researchers. Such materials mostly use magnetic substances (such as magnetite, nickel oxide, etc.) as the core component of microwave absorption, but they are prone to demagnetization in high-temperature and high-corrosion environments, resulting in the loss of microwave absorption performance, which greatly limits their application in complex environments.
[0004] Therefore, the preparation of dielectric materials with excellent low-frequency microwave absorption performance has become a core hotspot of current research. Existing research has shown that the introduction of a heterojunction interface into high-specific-surface-area materials such as graphene can significantly improve the low-frequency absorption performance of dielectric materials. Based on this, the application proposes a preparation method of a graphene / titanium dioxide composite low-frequency microwave absorption material, which is characterized by the use of the spatial edge selectivity generated when graphene forms a heterojunction interface to strengthen the material's ability to absorb low-frequency microwaves. SUMMARY
[0005] To solve the above problems, the application discloses a graphene / titanium dioxide composite low-frequency microwave absorption material and a preparation method thereof. Graphene is used as the raw material, and tetrabutyl titanate is used as the titanium source. By constructing a heterojunction interface with unique spatial selectivity and adding polyvinyl alcohol as a surfactant, the particle size of titanium dioxide during hydrolysis is adjusted by adjusting the amount of polyvinyl alcohol added, so as to optimize the low-frequency microwave absorption performance of the composite low-frequency microwave absorption material.
[0006] To achieve the above purpose, the application provides the following technical scheme: A preparation method of a graphene / titanium dioxide composite low-frequency microwave absorption material, comprising: dissolving polyvinyl alcohol, mixing raw materials, hydrothermal treatment, and post-treatment; The polyvinyl alcohol is dissolved by mixing deionized water and anhydrous ethanol, adding polyvinyl alcohol, and stirring until completely dissolved to obtain a polyvinyl alcohol solution; The volume ratio of deionized water to anhydrous ethanol in the dissolved polyvinyl alcohol is 1:1.8-2.2; The dosage ratio of deionized water to polyvinyl alcohol is 20 mL:1.8-2.2 g; The model of the polyvinyl alcohol is polyvinyl alcohol 2488; When stirring until completely dissolved, the stirring speed is 500-600 rpm, the temperature is 60-65℃, and the time is 6-7 hours; The mixed raw materials are added with a titanium source and graphene powder after cooling the polyvinyl alcohol solution, ultrasonic dispersion, stirring, to obtain a mixed solution; The mass ratio of polyvinyl alcohol in the polyvinyl alcohol solution to the titanium source in the mixed raw materials is 1.8-2.2:0.1-0.6; The mass ratio of polyvinyl alcohol in the polyvinyl alcohol solution to the graphene powder is 1.8-2.2:0.1; Preferably, the titanium source is butyl titanate; The model of the graphene powder is AP-3, and the d50 particle size is 5 μm; The power of the ultrasonic dispersion is 250-350 W, and the time is 20-30 minutes; Preferably, the stirring is magnetic stirring; The stirring speed of the stirring is 500-600 rpm, and the time is 2-3 hours; The hydrothermal treatment is to perform a hydrothermal reaction on the mixed solution to obtain a hydrothermal reaction product; In the hydrothermal treatment, the temperature of the hydrothermal reaction is 180-190℃, and the time is 16-17 hours; Preferably, the hydrothermal reaction is performed in a polytetrafluoroethylene inner liner; The post-treatment is to centrifuge the hydrothermal reaction product, take the bottom product, wash, freeze-dry, to obtain a graphene / titanium dioxide composite low-frequency microwave absorption material; In the post-treatment, the centrifugal speed of the centrifugation is 8000-9000 rpm, and the time is 10-12 minutes; The washing is to wash with deionized water and ethanol for 3-5 times respectively; The temperature of the freeze-drying is -65℃ to -55℃, and the time is 22-30 hours.
[0007] A graphene / titanium dioxide composite low-frequency microwave absorption material prepared by the preparation method.
[0008] The beneficial technical effects of the present application are as follows: (1) The preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material of the present invention uses polyvinyl alcohol as a surfactant, combines ultrasound and magnetic stirring, effectively suppresses the growth trend of TiO2 particles during hydrolysis, prepares nano-scale titanium dioxide particles, and increases the heterogeneous interface in contact with the graphene surface; (2) The preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material of the present invention realizes the generation of TiO2 through a hydrothermal reaction, utilizes the edge reaction activity of the graphene surface, prepares a titanium dioxide heterogeneous interface with edge modification, and enhances the low-frequency microwave absorption performance of the composite material; (3) The preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material of the present invention can change the composite heterogeneous interface structure of titanium dioxide on the graphene surface by adjusting the amount of butyl titanate added, thereby adjusting the low-frequency microwave absorption frequency of the material to meet different performance requirements; (4) The preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material of the present invention utilizes the edge reaction activity of graphene to form a large number of titanium dioxide heterogeneous interfaces at the edges of graphene. These heterogeneous interfaces introduce additional polarization sites, amplifying the interface polarization effect. When microwaves penetrate the material, the free carriers at the heterogeneous interface generate space charge accumulation under the action of the applied electric field, forming an electric dipole moment, thereby dissipating microwave energy. Due to the interface impedance effect, this process exhibits an extended relaxation time, thereby improving the dissipation efficiency of low-frequency microwaves. These findings provide valuable insights into the research of heterogeneous interface engineering and microwave absorbing materials, and demonstrate the great potential for the development of new low-frequency microwave absorbing materials. (5) The preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material of the present invention, the minimum reflection loss RL value of the prepared graphene / titanium dioxide composite low-frequency microwave absorbing material is -52.13dB to -27.49dB, the electromagnetic wave frequency corresponding to the minimum reflection loss RL value is 3.76-4.24GHz, and the effective absorption bandwidth is 1.46-1.88GHz. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 HAADF image and energy spectrum element analysis (EDS) distribution diagram of the transmission electron microscope (TEM) of the graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 3; Among them, Figure (a) is the HAADF diagram of the graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 3; Figure (b) is the EDS diagram of C, O, and Ti elements; Figure (c) is the EDS diagram of C element; Figure (d) is the EDS diagram of O element; Figure (e) is the EDS diagram of Ti element; Figure (f) is the EDS diagram of C and Ti elements.
[0010] Figure 2Graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 1-4; wherein, Figure 2 (a1) and Figure 2 (b1) is the wave absorption performance schematic diagram of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 1; Figure 2 (a2) and Figure 2 (b2) is the wave absorption performance schematic diagram of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 2; Figure 2 (a3) and Figure 2 (b3) is the wave absorption performance schematic diagram of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 3; Figure 2 (a4) and Figure 2 (b4) is the wave absorption performance schematic diagram of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 4.
[0011] Figure 3 Scanning electron microscope (SEM) images of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Examples 1-4 and Comparative Examples 1-2, 4, 6, 7; wherein, Figure 3 (a) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 1, Figure 3 (b) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 2, Figure 3 (c) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 3, Figure 3 (d) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Example 4, Figure 3 (e) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Comparative Example 1, Figure 3 (f) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Comparative Example 2, Figure 3 (g) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Comparative Example 4, Figure 3 (h) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Comparative Example 6, (i) is the SEM image of graphene / titanium dioxide composite low-frequency microwave absorbing material prepared in Comparative Example 7. DETAILED DESCRIPTION
[0012] The following detailed description of various exemplary embodiments of the application should not be considered to be limiting of the application, but rather a description of certain specific aspects, features, and embodiments of the application. It is understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application.
[0013] In addition, for numerical ranges of the present application, it is understood that every value and sub-range within the upper and lower limits of that range is specifically disclosed. Intervening values and sub-ranges between any stated value or stated range, and any other stated value or stated range, are also included herein. The upper and lower limits of these smaller ranges can be independently included or excluded from the ranges.
[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
[0015] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having", and the like are open-ended terms that are intended to mean including, but not limited to.
[0016] The raw materials used in the following examples and comparative examples of the present application are all commercially available products, and the specific details are shown in the following table:
[0017] The polyvinyl alcohol used in the present application is a product of the type polyvinyl alcohol 2488.
[0018] Example 1 A preparation method of a graphene / titanium dioxide composite low-frequency microwave absorbing material, specifically comprising: (1) 20 mL of deionized water and 40 mL of anhydrous ethanol are mixed to obtain a homogeneous solution, 2 g of polyvinyl alcohol is added, and the solution is heated on a 60°C constant temperature heating table at a speed of 520 rpm for 6 hours to completely dissolve, to obtain a polyvinyl alcohol solution; (2) After the polyvinyl alcohol solution is cooled to room temperature, 0.1 g of butyl titanate and 0.1 g of graphene powder are added, and ultrasonic dispersion is performed at a power of 300 W for 20 minutes, followed by magnetic stirring at a speed of 520 rpm for 2 hours to obtain a mixed solution; (3) The mixed solution is transferred to a 100 mL polytetrafluoroethylene liner and placed in a high-pressure kettle in a 180°C constant temperature heating box for reaction for 16 hours; (4) After the reaction is completed, the mixture in the reaction kettle is taken out, placed in a centrifuge at a speed of 8000 rpm for 10 minutes, and then the bottom product is collected, washed with deionized water and ethanol for 3 times respectively, and freeze-dried at-60℃ for 24 hours to obtain the graphene / titanium dioxide composite low-frequency microwave absorption material.
[0019] The embodiment also provides a graphene / titanium dioxide composite low-frequency microwave absorption material prepared by the preparation method.
[0020] Embodiment 2 A preparation method of a graphene / titanium dioxide composite low-frequency microwave absorption material, specifically comprising the following steps: (1) 20 mL of deionized water and 40 mL of anhydrous ethanol are mixed to obtain a homogeneous solution, 2 g of polyvinyl alcohol is added, and the solution is magnetically stirred on a 60℃ constant temperature heating table at a speed of 520 rpm for 6 hours until completely dissolved to obtain a polyvinyl alcohol solution; (2) After the polyvinyl alcohol solution is cooled to room temperature, 0.2 g of butyl titanate and 0.1 g of graphene powder are added, and ultrasonic dispersion is performed at a power of 300 W for 20 minutes, followed by magnetic stirring at a speed of 520 rpm for 2 hours to obtain a mixed solution; (3) The mixed solution is transferred to a 100 mL polytetrafluoroethylene liner and placed in an autoclave, and reacted in a 180℃ constant temperature heating box for 16 hours; (4) After the reaction is completed, the mixture in the reaction kettle is taken out, placed in a centrifuge at a speed of 8000 rpm for 10 minutes, and then the bottom product is collected, washed with deionized water and ethanol for 3 times respectively, and freeze-dried at-60℃ for 24 hours to obtain the graphene / titanium dioxide composite low-frequency microwave absorption material.
[0021] The embodiment also provides a graphene / titanium dioxide composite low-frequency microwave absorption material prepared by the preparation method.
[0022] Embodiment 3 A preparation method of a graphene / titanium dioxide composite low-frequency microwave absorption material, specifically comprising the following steps: (1) 20 mL of deionized water and 40 mL of anhydrous ethanol are mixed to obtain a homogeneous solution, 2 g of polyvinyl alcohol is added, and the solution is magnetically stirred on a 60℃ constant temperature heating table at a speed of 520 rpm for 6 hours until completely dissolved to obtain a polyvinyl alcohol solution; (2) After the polyvinyl alcohol solution is cooled to room temperature, 0.2 g of butyl titanate and 0.1 g of graphene powder are added, and ultrasonic dispersion is performed at a power of 300 W for 20 minutes, followed by magnetic stirring at a speed of 520 rpm for 2 hours to obtain a mixed solution; (3) The mixed solution is transferred to a 100 mL polytetrafluoroethylene liner and placed in an autoclave, and reacted in a 180℃ constant temperature heating box for 16 hours; (4) After the reaction is completed, the mixture in the reaction kettle is taken out, put into a centrifuge at a speed of 8000 rpm for 10 minutes, and then the bottom product is collected, washed with deionized water and ethanol for 3 times respectively, and freeze-dried at -60℃ for 24 hours to obtain the graphene / titanium dioxide composite low-frequency microwave absorption material.
[0023] The embodiment also provides a graphene / titanium dioxide composite low-frequency microwave absorption material prepared by the preparation method.
[0024] Example 4 A preparation method of a graphene / titanium dioxide composite low-frequency microwave absorption material, specifically comprising the following steps: (1) 20 mL of deionized water and 40 mL of anhydrous ethanol are mixed to obtain a homogeneous solution, 2 g of polyvinyl alcohol is added, and the solution is magnetically stirred on a 60℃ constant temperature heating table at a speed of 520 rpm for 6 hours until completely dissolved to obtain a polyvinyl alcohol solution; (2) After the polyvinyl alcohol solution is cooled to room temperature, 0.6 g of butyl titanate and 0.1 g of graphene powder are added, and ultrasonic dispersion is performed at a power of 300 W for 20 minutes, followed by magnetic stirring at a speed of 520 rpm for 2 hours to obtain a mixed solution; (3) The mixed solution is transferred into a 100 mL polytetrafluoroethylene liner and put into an autoclave, and reacted in a 180℃ constant temperature heating box for 16 hours; (4) After the reaction is completed, the mixture in the reaction kettle is taken out, put into a centrifuge at a speed of 8000 rpm for 10 minutes, and then the bottom product is collected, washed with deionized water and ethanol for 3 times respectively, and freeze-dried at -60℃ for 24 hours to obtain the graphene / titanium dioxide composite low-frequency microwave absorption material.
[0025] The embodiment also provides a graphene / titanium dioxide composite low-frequency microwave absorption material prepared by the preparation method.
[0026] Comparative Example 1 Compared with Example 3, the only difference is that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorption material, 20 mL of deionized water and 40 mL of anhydrous ethanol are changed to 40 mL of deionized water and 20 mL of anhydrous ethanol in step (1).
[0027] Comparative Example 2 Compared with Example 3, the only difference is that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorption material, 40 mL of deionized water is used instead of 40 mL of anhydrous ethanol in step (1).
[0028] Comparative Example 3 The difference compared with Example 3 is only that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material, 20 mL of anhydrous ethanol is used instead of 20 mL of deionized water in step (1).
[0029] Comparative Example 4 The difference compared with Example 3 is only that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material, no polyvinyl alcohol is added in step (1).
[0030] Comparative Example 5 The difference compared with Example 3 is only that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material, 4 g of polyvinyl alcohol is added in step (1).
[0031] Comparative Example 6 The difference compared with Example 3 is only that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material, 1 g of polyvinyl alcohol is added in step (1).
[0032] Comparative Example 7 The difference compared with Example 3 is only that in the preparation method of the graphene / titanium dioxide composite low-frequency microwave absorbing material, 1 g of butyl titanate is added in step (2).
[0033] Performance Test (1) The graphene / titanium dioxide composite low-frequency microwave absorbing materials prepared in Examples 1-4 and Comparative Examples 1-7 were subjected to electromagnetic wave absorption performance tests. The test results are as follows:
[0034] According to the above test results, a comparison of Examples 1-4 and Comparative Examples 1-2 shows that anhydrous ethanol is crucial for inhibiting the hydrolysis of butyl titanate; a comparison of Examples 1-4 and Comparative Example 3 shows that deionized water is a necessary condition for the conversion of butyl titanate into titanium dioxide particles and cannot be replaced by anhydrous ethanol; a comparison of Examples 1-4 and Comparative Examples 4-6 shows that polyvinyl alcohol can effectively inhibit the growth of titanium dioxide particles, so the size of titanium dioxide particles can be regulated by controlling the amount of polyvinyl alcohol added, but excessive polyvinyl alcohol will cause the solution to be viscous and ultimately unable to be shaped; a comparison of Examples 1-4 and Comparative Example 7 shows that by changing the amount of butyl titanate added, the edge heterojunction structure of the graphene / titanium dioxide composite material can be effectively regulated. The graphene edge is active, and titanium dioxide particles will preferentially react with the graphene edge; when the amount of titanium dioxide particles is excessive, they will grow towards the inner surface of the graphene. Therefore, the graphene edge heterojunction structure can be regulated by changing the amount of butyl titanate added, so as to achieve the best wave absorption performance.
[0035] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application.
Claims
1. A method for preparing a graphene / titanium dioxide composite low-frequency microwave absorbing material, characterized in that: include: Dissolving polyvinyl alcohol, mixing raw materials, hydrothermal treatment, post-processing; The mixed raw materials are cooled polyvinyl alcohol solution, and then titanium source and graphene powder are added, ultrasonically dispersed, and stirred to obtain a mixed solution; The hydrothermal treatment is to subject the mixed solution to a hydrothermal reaction to obtain a hydrothermal reaction product.
2. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 1, wherein: The polyvinyl alcohol is dissolved by mixing deionized water and anhydrous ethanol, adding the polyvinyl alcohol, and stirring until the polyvinyl alcohol is completely dissolved to obtain a polyvinyl alcohol solution.
3. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 2, wherein: In the dissolved polyvinyl alcohol, the volume ratio of deionized water to anhydrous ethanol is 1:1.8-2.2; The ratio of deionized water to polyvinyl alcohol is 20 mL: 1.8-2.2 g; The model of the polyvinyl alcohol is polyvinyl alcohol 2488.
4. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 2, wherein: The polyvinyl alcohol is dissolved and stirred until it is completely dissolved at a stirring speed of 500-600 rpm, a temperature of 60-65° C., and a time of 6-7 hours.
5. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 1, wherein: In the mixed raw material, the mass ratio of polyvinyl alcohol to titanium source in the polyvinyl alcohol solution is 1.8-2.2:0.1-0.6; The mass ratio of polyvinyl alcohol to graphene powder in the polyvinyl alcohol solution is 1.8-2.2:0.1; The graphene powder has a model of AP-3 and a d50 particle size of 5 μm; The titanium source is butyl titanate.
6. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 1, wherein: In the mixed raw materials, the power of the ultrasonic dispersion is 250-350W, and the time is 20-30 minutes; The stirring is magnetic stirring; The stirring speed is 500-600 rpm and the time is 2-3 hours.
7. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 1, characterized in that: In the hydrothermal treatment, the temperature of the hydrothermal reaction is 180-190° C. and the time is 16-17 hours; The hydrothermal reaction was carried out in a polytetrafluoroethylene-lined container.
8. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 1, wherein: The post-treatment comprises centrifuging the hydrothermal reaction product, taking the bottom product, washing it, and freeze-drying it to obtain the graphene / titanium dioxide composite low-frequency microwave absorbing material.
9. The method for preparing the graphene / titanium dioxide composite low-frequency microwave absorbing material according to claim 8, characterized in that: In the post-treatment, the centrifugal speed is 8000-9000 rpm and the time is 10-12 minutes; The washing is performed by washing with deionized water and ethanol 3-5 times each; The freeze-drying temperature is -65°C to -55°C, and the time is 22-30 hours.
10. A graphene / titanium dioxide composite low-frequency microwave absorbing material prepared by the preparation method according to any one of claims 1 to 9.