A flake MoS2@snowflake VO2(M) nanostructured electromagnetic wave absorbing material and its preparation method

Abstract

A flaky MoS2@snowflake-shaped VO2(M) nanostructured electromagnetic wave absorption material and its preparation method are described. First, a natural molybdenite raw material is subjected to electrochemical exfoliation to obtain a single or at least a few layers of MoS2 nanosheets. Snowflake-shaped VO2(B) nanostructures are then grown in situ on the surface of the MoS2 nanosheets via a hydrothermal synthesis process. Finally, the resulting precursor is heat-treated to induce the VO2(B) crystal form to transform into VO2(M), thereby producing a flaky MoS2@snowflake-shaped VO2(M) nanocomposite material. This synthesis method significantly improves the material's dielectric loss characteristics by constructing a synergistic system of a unique snowflake-shaped hierarchical structure and high-specific-surface-area MoS2 nanosheets. The resulting composite material exhibits excellent microwave absorption performance, providing a new technical approach for the design of high-performance electromagnetic wave absorption materials.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave absorbing materials, and in particular to a flaky MoS2@snowflake-shaped VO2(M) nanostructured electromagnetic wave absorbing material and a preparation method thereof. Background Art

[0002] The rapid development of electronics and wireless communications has ushered in a new era of electromagnetic wave applications. However, this has also brought with it the serious problem of electromagnetic pollution, which cannot be ignored. Research has shown that absorbent materials can convert electromagnetic waves into other forms of energy, effectively reducing electromagnetic wave pollution. In recent years, absorbent materials such as carbon-based materials, magnetic materials, conductive polymers, and metal oxides / sulfides have been widely studied and applied. M-phase vanadium dioxide (VO2(M)) is a binary metal oxide with a strongly correlated electron system. Due to the strong interactions between its electrons, orbitals, lattices, and spins, small external stimuli can trigger changes in the local electronic and crystal structure, inducing a reversible metal-insulator phase transition in VO2(M). During this phase transition, VO2(M) undergoes significant changes in its physical properties, including its crystal structure, electrical resistance, infrared transmittance, and refractive index. Because VO2(M) has a phase transition temperature close to room temperature and exhibits significant changes in its physical and chemical properties before and after the phase transition, it shows great potential for application in a wide range of fields, including smart windows, photoelectric switches, batteries, and supercapacitors. However, research and application of VO2(M) in the field of electromagnetic wave absorption are relatively limited. The main reason is its weak conductivity and low dielectric loss, which leads to poor electromagnetic wave attenuation ability.

[0003] In recent years, molybdenum disulfide, an emerging two-dimensional nanomaterial, has sparked extensive research in the field of electromagnetic wave absorption due to its abundant surface defects, high specific surface area, and excellent dielectric loss properties. In electromagnetic wave absorption applications, the strong interaction between MoS2 nanosheets can induce a significant polarization effect, which in turn leads to efficient electromagnetic wave dielectric loss. This property gives it great potential for the development of high-performance electromagnetic wave absorption materials.

[0004] The prior art CN116410697A core-shell structure MoS2@VO2 composite material, preparation method and application discloses a core-shell structure MoS2@VO2 composite material. The solvent used in its preparation is toxic isopropyl alcohol, and the prepared product has a matching thickness of 3mm and a narrow effective absorption bandwidth, which shows that its absorption performance is poor. Summary of the Invention

[0005] Aiming at the shortcomings of the prior art in using non-environmentally friendly reagents in the preparation process and the low absorption performance of the product, the present invention provides a method for preparing a sheet-like MoS2@snowflake-like VO2(M) nanostructured electromagnetic wave absorbing material.

[0006] The present invention first electrochemically exfoliates natural molybdenite to produce few-layer or single-layer MoS2 flakes. Research has shown that this electrochemical exfoliation of natural molybdenite yields high-purity 2H-MoS2 nanosheets. This process not only effectively maintains the integrity of the material's crystal structure but also significantly increases its specific surface area. The embedding of tetrabutylammonium ions (TBA⁺) increases the interlayer spacing of the molybdenite. This larger specific surface area facilitates the incorporation of VO2(M) materials. The increased interlayer spacing creates nanometer-scale gaps between the stacked two-dimensional flakes, further enhancing multiple reflections and scattering of incident waves and providing more contact points for electromagnetic waves. Together with the dipole polarization loss of MoS2 itself, this contributes to its strong dielectric loss. VO2(M) itself has low dielectric loss and poor microwave absorption properties, so it needs to be composited with a high-dielectric material to increase its dielectric loss and optimize its microwave absorption properties. Compared to the existing core-shell MoS2@VO2 composite material, preparation method, and application described in CN116410697A, our method utilizes safer and more harmless deionized water as a solvent. Using the aforementioned MoS2 nanosheets as a substrate, we in situ grow snowflake-like VO2(B) nanostructures on their surfaces via a hydrothermal synthesis process. This is due to the Ostwald ripening effect, which causes small VO2 particles in the heterogeneous reaction system to redissolve and deposit on larger MoS2 particles. Finally, the resulting precursor is heat-treated to induce the VO2(B) crystal phase to transform into VO2(M), thereby producing the flake-like MoS2@snowflake-like VO2(M) nanocomposite. This synthesis method significantly enhances the dielectric loss characteristics of the material by constructing a unique synergistic system of snowflake-like VO2(M) and high-surface-area MoS2 nanosheets. The resulting composite exhibits excellent microwave absorption performance, providing a new technical approach for the design of high-performance electromagnetic wave absorption materials.

[0007] This invention uses flake MoS2 as a substrate and, through the synergistic effects of hydrothermal synthesis and heat treatment, in situ grows VO2(M) nanostructures on its surface. The resulting heterogeneous composite material, in situ loaded with snowflake-like VO2(M) nanostructures, is constructed. This composite material, through its unique microstructural design, exhibits the synergistic advantages of a wide effective absorption band and high electromagnetic wave absorption efficiency at a low matching thickness.

[0008] The technical problem that the present invention also aims to solve is to provide a method for preparing the above-mentioned two-dimensional nanostructured MoS2@VO2(M) electromagnetic wave absorbing material. This method does not require the use of highly toxic organic solvents, has simple steps, strong controllability, low cost, and can be used for large-scale industrial production.

[0009] The specific technical solutions of the present invention are as follows:

[0010] A method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material comprises the following steps:

[0011] Step 1: Use electrochemical method to strip natural molybdenite, and then use ethanol ultrasonic cleaning to obtain 2H phase two-dimensional sheet MoS2 nanosheets;

[0012] Step 2: First, V2O5 and H2C2O4 are added to water and heated with stirring until a dark blue solution is obtained; then, two-dimensional flaky MoS2 nanosheets are added to the dark blue solution, and after ultrasonic dispersion treatment, the solution is transferred to a reactor for a hydrothermal reaction. The VO2 generated in the reaction system is redissolved and deposited by the Ostwald ripening effect, thereby achieving uniform coating of the surface of the two-dimensional flaky MoS2 nanosheets of the 2H phase by the VO2 deposits of the B phase;

[0013] After centrifugation and drying, the MoS2@VO2(B) composite material was obtained.

[0014] Step 3: calcining the MoS2@VO2(B) composite material prepared in step 2 to convert VO2 from B phase to M phase to obtain MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material; the VO2 is snowflake-shaped particles with a particle size of 300~700nm.

[0015] Preferably, in step 1, the electrochemical stripping specifically comprises: performing electrochemical stripping using a tetrabutylammonium bromide acetonitrile solution with a concentration of 8 mg / ml.

[0016] Preferably, in step 1, in the electrochemical stripping, the DC voltage used is 12V, the platinum electrode is connected to the positive electrode, the molybdenite sheet is connected to the negative electrode, and the electrochemical stripping time is 8 hours.

[0017] Preferably, the two-dimensional flaky MoS2 nanosheets of the 2H phase in step 1 include a combination of a single-layer MoS2 nanosheet and a single-layer MoS2 nanosheet with less than 5 layers overlapping each other;

[0018] For an assembly formed by overlapping less than 5 single-layer MoS2 nanosheets, in step 2, the VO2 deposit of phase B is deposited on the outer surface of the assembly, and is not deposited between adjacent single-layer MoS2 nanosheets in the assembly.

[0019] Preferably, the treatment time of the ethanol ultrasonic cleaning in step 1 is 20 minutes.

[0020] Preferably, in step 2, the mass ratio of the two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is (20-60): 545.64: 810.36: 70000;

[0021] Preferably, in step 2, the reaction temperature of the hydrothermal reaction is 200° C. and the reaction time is 12 h.

[0022] Preferably, in step 3, the calcination specifically comprises: heating to 500°C at a heating rate of 5°C / min in an argon atmosphere and keeping the temperature for 3 h.

[0023] Preferably, the applicable electromagnetic wave frequency of the flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material is adjusted by adjusting the dosage ratio of the two-dimensional flaky MoS2 nanosheets, V2O5, H2C2O4, and water in step 2:

[0024] The electromagnetic wave frequency is 12.12 GHz, and the mass ratio of two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 20:545.64:810.36:70000;

[0025] The electromagnetic wave frequency is 14 GHz, and the mass ratio of two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 40:545.64:810.36:70000;

[0026] The frequency of the electromagnetic wave is 4.92 GHz, and the mass ratio of two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 60:545.64:810.36:70000.

[0027] The present invention also provides a flaky MoS2@snowflake-shaped VO2 (M) electromagnetic wave absorbing material prepared by the preparation method.

[0028] The present invention's flake MoS2@snowflake-shaped VO2(M) preparation principle involves first subjecting natural molybdenite to electrochemical exfoliation to obtain monolayer or at least monolayer MoS2 nanosheets. Next, using the MoS2 nanosheets as a substrate, snowflake-shaped VO2(B) nanostructures are in situ grown on their surfaces via a hydrothermal synthesis process. Finally, the resulting precursor is heat-treated to induce the transformation of the VO2(B) crystal form to VO2(M), thereby producing a flake MoS2@snowflake-shaped VO2(M) nanocomposite. The electromagnetic properties of this electromagnetic wave absorbing material can be regulated by the MoS2 doping ratio. This allows for the production of more flake MoS2@snowflake-shaped VO2(M) composite materials. The unique MoS2 structure in this nanomaterial not only creates a conductive network, significantly improving electrical conductivity, but also enhances multipolarization relaxation. Furthermore, the snowflake-shaped VO2(M) deposited on the MoS2 expands the propagation path of electromagnetic waves, enabling multiple reflections and scattering, thereby enhancing their absorption.

[0029] Advantageous Effects of the Invention

[0030] (1) The natural molybdenite stripped by electrochemical method has a large specific surface area and is embedded with tetrabutylammonium ions (TBA⁺), which has excellent electrical conductivity. The resulting electrical conductivity loss and the dipole polarization loss of MoS2 itself together constitute an important basis for strong dielectric loss.

[0031] (2) Compared with the prior art CN116410697A core-shell structure MoS2@VO2 composite material, preparation method and application, the nano-array structure of the present invention, which is a composite of flake MoS2 substrate and snowflake VO2(M), has a larger specific surface area and richer interfaces. In the nano-array structure, the snowflake VO2(M) is evenly distributed on the flake MoS2 substrate, forming a large number of heterogeneous interfaces, providing more scattering and absorption sites for electromagnetic waves. In contrast, in the core-shell heterogeneous structure MoS2@VO2(M), MoS2 is wrapped around the VO2(M) core as a shell, and its interfaces are relatively few and the specific surface area is also small, which is not conducive to the full absorption of electromagnetic waves. In addition, in the complex nano-array structure constructed by the MoS2 substrate and the snowflake VO2(M), the electromagnetic wave will undergo multiple reflections and scattering phenomena when propagating in it, which greatly extends the propagation path of the electromagnetic wave and enables the electromagnetic wave energy to be more fully dissipated in this process. Finally, there is a significant interface polarization effect between the MoS2 substrate and VO2(M). This interface polarization effect can effectively capture and consume electromagnetic wave energy, significantly enhancing the energy attenuation of electromagnetic waves.

[0032] (3) The present invention does not require the use of highly toxic chemical reagents for preparation. The method is simple, highly controllable, and low-cost, making it suitable for large-scale industrial production. This important result also provides a strong theoretical basis and experimental foundation for the research and development of ideal microwave absorbing materials.

[0033] (4) Compared with the prior art CN116410697A core-shell structure MoS2@VO2 composite material, preparation method and application, when the matching thickness is 3mm, its minimum reflection loss is -56.78dB and the optimal effective absorption bandwidth is 4GHz. When the matching thickness is 1.55mm and the frequency is 14GHz, the minimum reflection loss of the present invention can reach -55.19dB; when the matching thickness is 1.41mm, the optimal effective bandwidth is 5.28GHz. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific embodiments or the description of the prior art. Hereinafter, some specific embodiments of the present invention will be described in detail in an illustrative and non-limiting manner with reference to the drawings. The same reference numerals in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0035] Figure 1 X-ray diffraction patterns of VO2(M), MoS2 and MoS2@VO2(M) prepared in the present invention;

[0036] Figure 2 This is a SEM image of MoS2-20@VO2(M) prepared in Example 1 of the present invention;

[0037] Figure 3 This is a SEM image of MoS2-40@VO2(M) prepared in Example 2 of the present invention;

[0038] Figure 4 This is a SEM image of MoS2-60@VO2(M) prepared in Example 3 of the present invention;

[0039] Figure 5 This is a reflection loss diagram of MoS2-20@VO2(M) prepared in Example 1 of the present invention;

[0040] Figure 6 This is a reflection loss diagram of MoS2-40@VO2(M) prepared in Example 2 of the present invention;

[0041] Figure 7 This is a reflection loss diagram of MoS2-60@VO2(M) prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0043] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0044] The preparation method of the MoS2@VO2(M) absorbing material of the present invention specifically comprises the following steps:

[0045] Example 1

[0046] In step 1, a natural molybdenite flake and platinum foil were used as the cathode and anode, respectively, in a two-electrode system. First, 160 mg of tetrabutylammonium bromide (TBAB) was dissolved in acetonitrile to prepare an acetonitrile solution with a concentration of 8 mg / mL. Next, an electric field was applied to the system using a 12 V DC power supply for 8 hours. Subsequently, the treated molybdenite was placed in anhydrous ethanol and ultrasonically treated for 20 minutes to achieve complete exfoliation. Finally, the exfoliated product was placed in a freeze dryer and dried for 12 hours to obtain 2H-MoS2 with a metallic luster.

[0047] Step 2: First, weigh 3 mmol of V2O5 and 9 mmol of H2C2O4, place them in 70 mL of deionized water, and stir continuously until completely dissolved. Next, transfer the mixed solution to an oil bath, set the temperature to 80°C, and stir continuously for 1 hour until the solution becomes a uniform dark blue. Subsequently, add 20 mg of MoS2 that has been exfoliated to the above solution and ultrasonicate for 30 minutes to ensure that MoS2 is evenly dispersed. After that, transfer the mixed solution to a 100 mL hydrothermal reactor and react at 200°C for 12 hours. After the reaction is completed, the MoS2-20@VO2(B) composite material is finally obtained after washing and drying.

[0048] Step 3: Place the obtained MoS2-20@VO2(B) in an argon atmosphere, heat it to 500°C at a heating rate of 5°C / min, and heat treat it at this temperature for 3 hours to finally obtain MoS2-20@VO2(M).

[0049] Example 2

[0050] In step 1, a natural molybdenite flake and platinum foil were used as the cathode and anode, respectively, in a two-electrode system. First, 160 mg of tetrabutylammonium bromide (TBAB) was dissolved in acetonitrile to prepare an acetonitrile solution with a concentration of 8 mg / mL. Next, an electric field was applied to the system using a 12 V DC power supply for 8 hours. Subsequently, the treated molybdenite was placed in anhydrous ethanol and ultrasonically treated for 20 minutes to achieve complete exfoliation. Finally, the exfoliated product was placed in a freeze dryer and dried for 12 hours to obtain 2H-MoS2 with a metallic luster.

[0051] Step 2. First, weigh 3mmol V2O5 and 9mmol H2C2O4, place them in 70mL deionized water, and stir continuously until completely dissolved. Then, transfer the mixed solution to an oil bath, set the temperature to 80°C, and stir continuously for 1 hour until the solution is uniformly dark blue. Subsequently, add 40mg of MoS2 that has been exfoliated to the above solution and ultrasonicate for 30 minutes to ensure that MoS2 is evenly dispersed. After that, transfer the mixed solution to a 100mL hydrothermal reactor and react at 200°C for 12 hours. After the reaction is completed, the MoS2-40@VO2(B) composite material is finally obtained after washing and drying.

[0052] Step 3: Place the obtained MoS2-40@VO2(B) in an argon atmosphere, heat it to 500°C at a heating rate of 5°C / min, and heat treat it at this temperature for 3 hours to finally obtain MoS2-40@VO2(M).

[0053] Example 3

[0054] In step 1, a natural molybdenite flake and platinum foil were used as the cathode and anode, respectively, in a two-electrode system. First, 160 mg of tetrabutylammonium bromide (TBAB) was dissolved in acetonitrile to prepare an acetonitrile solution with a concentration of 8 mg / mL. Next, an electric field was applied to the system using a 12 V DC power supply for 8 hours. Subsequently, the treated molybdenite was placed in anhydrous ethanol and ultrasonically treated for 20 minutes to achieve complete exfoliation. Finally, the exfoliated product was placed in a freeze dryer and dried for 12 hours to obtain 2H-MoS2 with a metallic luster.

[0055] Step 2: First, weigh 3 mmol of V2O5 and 9 mmol of H2C2O4, place them in 70 mL of deionized water, and stir continuously until completely dissolved. Next, transfer the mixed solution to an oil bath, set the temperature to 80°C, and stir continuously for 1 hour until the solution is uniformly dark blue. Subsequently, add 60 mg of MoS2 that has been exfoliated to the above solution and ultrasonicate for 30 minutes to ensure that MoS2 is evenly dispersed. After that, transfer the mixed solution to a 100 mL hydrothermal reactor and react at 200°C for 12 hours. After the reaction is completed, the MoS2-60@VO2(B) composite material is finally obtained after washing and drying.

[0056] Step 3: Place the obtained MoS2-60@VO2(B) in an argon atmosphere, heat it to 500°C at a heating rate of 5°C / min, and heat treat it at this temperature for 3 hours to finally obtain MoS2-60@VO2(M).

[0057] Figure 1The X-ray diffraction patterns of VO2(M), MoS2, and MoS2@VO2(M) are shown. Based on standard card PDF#37-1492, the characteristic diffraction peaks of MoS2 appear at 14.37°, 39.53°, 44.15°, and 60.14°, corresponding to its (002), (103), (006), and (008) crystal planes. After VO2(M) is grown on the MoS2 surface, the composite material exhibits characteristic diffraction peaks at 26.86°, 27.79°, and 37.08°, which fully match the (-111), (011), and (200) crystal planes of VO2(M) standard card PDF#43-1051. Overall analysis of the spectrum shows that the intensity of the characteristic diffraction peaks of MoS2 increases regularly with increasing MoS2 content, fully demonstrating that the MoS2@VO2(M) composite material has been successfully prepared.

[0058] Figure 2 , 3, and 4 are SEM images of MoS2-20@VO2(M), MoS2-40@VO2(M), and MoS2-60@VO2(M), respectively. It can be seen from the figures that as the amount of MoS2 substrate increases, more and more snowflake-shaped VO2(M) are obtained.

[0059] Figure 5 The reflection loss diagram of MoS2-20@VO2(M) is shown in Figure 2. Figure 5 It can be seen that MoS2-20@VO2(M) exhibits general microwave absorption performance. When the matching thickness is 1.78 mm and the frequency is 12.12 GHz, the maximum reflection loss can reach -27.75 dB; when the thickness is 1.71 mm, the optimal effective bandwidth is 3.32 GHz.

[0060] Figure 6 The reflection loss diagram of MoS2-40@VO2(M) is shown in Figure 2. Figure 6 It can be seen that MoS2-40@VO2(M) exhibits excellent microwave absorption performance. When the matching thickness is 1.55 mm and the frequency is 14 GHz, the maximum reflection loss can reach -55.19 dB; when the thickness is 1.41 mm, the optimal effective bandwidth is 5.28 GHz.

[0061] Figure 7 The reflection loss diagram of MoS2-60@VO2(M) is shown in Figure 2. Figure 7 It can be seen that MoS2-60@VO2(M) exhibits excellent microwave absorption performance. When the matching thickness is 3.34 mm and the frequency is 4.92 GHz, the maximum reflection loss can reach -55.88 dB; when the thickness is 1.33 mm, the optimal effective bandwidth is 5.64 GHz.

[0062] The microwave absorption performance of the present invention's flake MoS2@snowflake-shaped VO2(M) composite material primarily stems from the significant increase in both the real and imaginary parts of the complex permittivity of the MoS2@VO2(M) composite material after the introduction of flake MoS2. Simultaneously, its dielectric loss tangent also increases accordingly. This phenomenon fully demonstrates that the addition of MoS2 effectively improves the material's dielectric loss capability. This enhanced dielectric loss capability is primarily due to the following: firstly, both VO2(M) and MoS2 are dielectric loss materials; their combination gives the MoS2@VO2(M) composite material high intrinsic conductivity, resulting in higher conduction losses. Secondly, the interfacial polarization effect between the MoS2 substrate and VO2(M) further increases dielectric loss. Finally, the snowflake-shaped VO2(M) structure. This unique structure expands the propagation path of electromagnetic waves, enabling multiple reflection and scattering events, thereby improving electromagnetic wave absorption efficiency. The presence of multiple loss mechanisms ensures strong absorption of incident electromagnetic waves, allowing the present invention to achieve high reflection losses and a wide effective absorption bandwidth even at relatively low thicknesses.

[0063] Both the experimental and theoretical results of the present invention show that by means of ion intercalation, natural molybdenite is stripped into single-layer and few-layer nanosheets, and then compounded with VO2(M), the obtained two-dimensional nanostructured materials can exhibit more superior electromagnetic wave absorption performance.

[0064] The above description is only part of the specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the art within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material, characterized in that: The steps include: Step 1: Use electrochemical method to strip natural molybdenite, and then use ethanol ultrasonic cleaning to obtain 2H phase two-dimensional sheet MoS2 nanosheets; Step 2: First, V2O5 and H2C2O4 are added to water and heated with stirring until a dark blue solution is obtained; then, two-dimensional flaky MoS2 nanosheets are added to the dark blue solution, and after ultrasonic dispersion treatment, the solution is transferred to a reactor for a hydrothermal reaction. The VO2 generated in the reaction system is redissolved and deposited by the Ostwald ripening effect, thereby achieving uniform coating of the surface of the two-dimensional flaky MoS2 nanosheets of the 2H phase by the VO2 deposits of the B phase; After centrifugation and drying, the MoS2@VO2(B) composite material was obtained; Step 3: calcining the MoS2@VO2(B) composite material prepared in step 2 to convert VO2 from B phase to M phase to obtain MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material; the VO2 is snowflake-shaped particles with a particle size of 300~700nm.

2. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 1, characterized in that: In step 1, the electrochemical stripping specifically includes: performing electrochemical stripping using a tetrabutylammonium bromide acetonitrile solution with a concentration of 8 mg / ml.

3. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 2, characterized in that: In step 1, in the electrochemical stripping, the DC voltage used is 12V, the platinum electrode is connected to the positive electrode, the molybdenite sheet is connected to the negative electrode, and the electrochemical stripping time is 8 hours.

4. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 1, characterized in that: The two-dimensional flaky MoS2 nanosheets of the 2H phase in step 1 include a combination of a single-layer MoS2 nanosheet and a single-layer MoS2 nanosheet with less than 5 layers overlapping each other; For an assembly formed by overlapping less than 5 single-layer MoS2 nanosheets, in step 2, the VO2 deposit of phase B is deposited on the outer surface of the assembly, and is not deposited between adjacent single-layer MoS2 nanosheets in the assembly.

5. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 1, characterized in that: The processing time of the ethanol ultrasonic cleaning in step 1 is 20 minutes.

6. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 1, characterized in that: In step 2, the mass ratio of two-dimensional MoS2 nanosheets, V2O5, H2C2O4 and water is (20~60): 545.64: 810.36: 70000.

7. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 6, characterized in that: In step 2, the reaction temperature of the hydrothermal reaction is 200°C and the reaction time is 12h.

8. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 1, characterized in that: In step 3, the calcination specifically includes: heating to 500°C at a heating rate of 5°C / min in an argon atmosphere and keeping the temperature for 3 h.

9. The method for preparing a flaky MoS2@snowflake-shaped VO2(M) electromagnetic wave absorbing material according to claim 6, characterized in that: By adjusting the dosage ratio of the two-dimensional MoS2 nanosheets, V2O5, H2C2O4 and water in step 2, the applicable electromagnetic wave frequency of the MoS2@snowflake-shaped VO2(M) electromagnetic wave absorption material can be adjusted: The electromagnetic wave frequency is 12.12 GHz, the matching thickness is 1.78 mm, and the mass ratio of the two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 20:545.64:810.36:70000; The electromagnetic wave frequency is 14 GHz, the matching thickness is 1.55 mm, and the mass ratio of the two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 40:545.64:810.36:70000; The frequency of the electromagnetic wave is 4.92 GHz, the matching thickness is 3.34 mm, and the mass ratio of the two-dimensional MoS2 nanosheets, V2O5, H2C2O4, and water is 60:545.64:810.36:70000.

10. The flaky MoS2@snowflake-shaped VO2 (M) electromagnetic wave absorbing material prepared by the preparation method according to any one of claims 1 to 9.

Images