A zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material and its preparation method

Abstract

The present invention provides a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material and a preparation method thereof, belonging to the technical field of electromagnetic wave absorbing materials. The method first adds Ti3C2T x nanosheets into deionized water and stirs evenly to obtain a Ti3C2T x nanosheet suspension; dissolves Zn(CH3COO)2·2H2O in methanol to obtain a Zn(CH3COO)2·2H2O solution; finally mixes the two solutions, transfers them to a Teflon-sealed autoclave for reaction, and performs heat treatment in a tubular furnace under an argon atmosphere to obtain a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material. The composite microwave absorbing material has a rose-shaped, sandwich-like hamburger-shaped or spiny sea urchin-shaped structure. By partially oxidizing titanium carbide and introducing a material with a moderate dielectric constant, a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material with a special morphology is prepared to improve the problem of limited microwave absorbing performance caused by the too high conductivity of titanium carbide.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of microwave absorbing materials, and particularly relates to a zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite microwave absorbing material and a preparation method thereof. Background Art

[0002] With the vigorous development of wireless communication devices and electronic devices, the problem of electromagnetic pollution has become increasingly serious. The leakage of electromagnetic waves not only affects the precise operation of devices and human health, but also endangers national security. Therefore, the development of microwave absorbing materials with both high absorption intensity and wide absorption bandwidth has attracted extensive interest. At present, great progress has been made in the research of microwave absorbing materials. Understanding the relationship between the morphology, size, composition and absorption characteristics of materials is the key to fundamentally solving the bottleneck problem, which not only helps to understand the microwave absorption mechanism, but also guides the synthesis of electromagnetic wave absorbing materials from a new perspective. Recent studies have shown that designing materials with multi-interfaces and multi-level structures can combine multiple electromagnetic loss mechanisms to obtain efficient absorption performance.

[0003] Titanium carbide (Ti3C2T x MXene, hereinafter referred to as Ti3C2T x ) as a unique family of two-dimensional transition metal carbides and / or nitrides, has broad application prospects in the field of electromagnetic wave absorption due to its high specific surface area, large specific surface area, excellent mechanical properties, hydrophilic surface and local dipoles. Its most remarkable feature is its high electrical conductivity comparable to that of metals. However, the high conductivity always makes the electron beam easily reflected to the surface rather than entering the interior, thereby reducing the electromagnetic wave absorption ability. Therefore, improving the electromagnetic wave absorption performance of Ti3C2T x is an urgent need for practical applications. There are mainly two methods to improve the electromagnetic wave absorption ability of Ti3C2T x . One is to oxidize Ti3C2T x to carbon-based TiO2, which can improve the dielectric loss and impedance matching; the other is to introduce another phase with a moderate dielectric constant into Ti3C2T x . In addition to TiO2, semiconductors such as ZnO, SiC and MoS2 are also usually introduced into Ti3C2T xAmong them, ZnO materials have become the preferred materials due to their wide bandgap, light weight, multiple functions, high cost performance, simple manufacturing, environmental protection and other advantages. However, the electromagnetic wave absorption performance of pure zinc oxide is not ideal. In order to improve the electromagnetic wave absorption performance of ZnO, researchers have prepared ZnO into special morphologies, such as three-layer porous flowers, nanorods, nanoparticles, etc. It has been proved that special morphological design can cause multiple reflections and scattering, extend the microwave propagation path, and consume more electromagnetic energy. Therefore, it is not difficult to find that in addition to the improvements brought by components, unique structural design, especially the structural design with heterogeneous interfaces, is crucial for improving the wave absorption performance. The multiple interfaces appearing in the heterostructure are similar to small microwave reflection cavities, providing a place for multiple reflections of electron flow, resulting in an extended propagation path of incident microwaves, thereby enhancing the absorption ability. Therefore, the electromagnetic wave absorption performance can be improved by designing more interfaces in a complex system structure. Integrating two-dimensional nanosheets into a structure with high porosity and large specific surface area is an effective method to adjust the wave absorption performance. Therefore, designing a TiO2 / Ti3C2T x / ZnO composite material formed by the aggregation of two-dimensional nanosheets into a three-dimensional flower-shaped heterostructure will be beneficial to improving the electromagnetic wave absorption ability. Because it is beneficial to extend the transmission path of incident electron flow, enhance the interfacial polarization effect, optimize the impedance matching and generate local defects. Although many Ti3C2T x -based heterostructures have been applied to the field of electromagnetic wave absorption in recent years, the ZnO / TiO2 / Ti3C2T x composite material with a series of unique three-dimensional structures based on regular layered rose morphology has not been reported, and there is also a lack of a clear understanding of the influence rules of ZnO and TiO2 type wave absorption materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a zinc oxide / titanium dioxide / titanium carbide composite wave absorption material and a preparation method thereof. This method prepares a zinc oxide / titanium dioxide / titanium carbide composite wave absorption material by partial oxidation of titanium carbide and introducing a material with a moderate dielectric constant, thereby improving the problem of limited wave absorption performance caused by too high conductivity of titanium carbide.

[0005] The present invention first provides a preparation method of a zinc oxide / titanium dioxide / titanium carbide composite wave absorption material, including:

[0006] Step 1: Add Ti3C2T x nanosheets to deionized water and stir evenly to obtain a Ti3C2T x nanosheet suspension;

[0007] Step 2: Dissolve Zn(CH3COO)2·2H2O in methanol to obtain a Zn(CH3COO)2·2H2O solution;

[0008] Step 3: Mix the Ti3C2T x nanosheet suspension in Step 1 and the Zn(CH3COO)2·2H2O solution in Step 2, transfer the mixture to a Teflon-sealed autoclave for reaction, and after centrifugation, washing, and freeze-drying, perform heat treatment in a tubular furnace under an argon atmosphere to obtain a zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material.

[0009] Preferably, the mass ratio of the Ti3C2T x nanosheets to deionized water in Step 1 is 1:150.

[0010] Preferably, the mass of Zn(CH3COO)2·2H2O in g: the volume of methanol in mL in Step 2 is 1:50.

[0011] Preferably, the reaction temperature in Step 3 is 160 - 180 °C, and the reaction time is 22 - 24 h.

[0012] Preferably, the freeze-drying time in Step 3 is 40 - 50 h, and the pressure is 0.1 - 0.2 Pa.

[0013] Preferably, the heat treatment temperature in Step 3 is 600 - 700 °C, and the time is 2 - 3 h.

[0014] Preferably, the mass ratio of Ti3C2T x to Zn(CH3COO)2·2H2O in Step 3 is (0.02 - 0.4):1.

[0015] The present invention also provides a zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material obtained by the above preparation method. The composite wave-absorbing material has a rose-shaped, sandwiched hamburger-shaped, or spiny sea urchin-shaped structure.

[0016] Advantages of the present invention

[0017] The present invention provides a zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave-absorbing material and its preparation method. The composite electromagnetic wave absorption material uses Ti3C2T x as both a precursor of a dielectric loss material and a crystal growth substrate. Without considering the interfacial stability between different components, Ti3C2T x is integrated with the dielectric loss material, reducing the effect of strong reflection and weak absorption caused by the high conductivity of Ti3C2T x itself. Through a simple and effective hydrothermal synthesis method and high-temperature ablation method, a wave-absorbing material with a special morphology and a tightly combined multi-interface structure of zinc oxide / titanium dioxide / titanium carbide is prepared. This material has the following characteristics:

[0018] First, through the design of a multi-layered flower-like structure and combination with a dielectric loss material, good impedance matching is obtained, enabling a large amount of electron beams to enter the wave-absorbing material and fully contact the internal interfaces of the wave-absorbing material, rather than being reflected on the material surface;

[0019] Second, surface defects are formed by using the heat treatment process and hydrothermal reaction, which is beneficial to dipole polarization and thus causes energy dissipation;

[0020] Third, the complex hierarchical structure and heterogeneous components of the composite material can generate a large number of interfaces and connection points, where a large amount of charges can be trapped, leading to interfacial polarization and associated relaxation. At the same time, the charge concentration is concentrated at the edges of the sheets, which can act as multipoles to promote stronger electromagnetic wave absorption.

[0021] Fourth, the prepared composite material has a small size and a large specific surface area, which will cause multiple reflections and scattering of the electron flow in the material, increasing the contact probability between the electron flow and the wave-absorbing material, thereby resulting in a greater degree of electron flow attenuation.

[0022] Fifth, the uniformly dispersed TiO2 nanocrystals form a large number of capacitor-like structures to further dissipate the electron beam. Finally, the moderate Ti3C2T x content and charge movement are beneficial to conductive loss and the consumption of electromagnetic energy. Description of the Drawings

[0023] Figure 1 SEM photograph of ZnO prepared in Comparative Example 1 of the present invention;

[0024] Figure 2 SEM photograph of the TiO2 / Ti3C2T x composite prepared in Comparative Example 2 of the present invention;

[0025] Figure 3 SEM photograph of the TiO2 / Ti3C2T x composite prepared in Comparative Example 3 of the present invention;

[0026] Figure 4 SEM photograph of the ZnO / TiO2 / Ti3C2T x composite prepared in Example 1 of the present invention;

[0027] Figure 5 SEM photograph of the ZnO / TiO2 / Ti3C2T x composite prepared in Example 1 of the present invention, with a partially enlarged SEM photograph;

[0028] Figure 6 SEM photograph of the ZnO / TiO2 / Ti3C2T x composite prepared in Example 2 of the present invention;

[0029] Figure 7 Scanning electron microscope photograph of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 3 of the present invention;

[0030] Figure 8 Scanning electron microscope photograph of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 4 of the present invention;

[0031] Figure 9 XRD spectrum of ZnO prepared in Comparative Example 1 of the present invention;

[0032] Figure 10 XRD spectrum of the TiO2 / Ti3C2T x composite prepared in Comparative Example 2 of the present invention;

[0033] Figure 11 XRD spectrum of the TiO2 / Ti3C2T x composite prepared in Comparative Example 3 of the present invention;

[0034] Figure 12 XRD spectrum of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 1 of the present invention;

[0035] Figure 13 XRD spectrum of the ZnO / TiO2 / Ti3C2T x locally enlarged XRD spectrum of the composite material prepared in Example 1 of the present invention;

[0036] Figure 14 XRD spectrum of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 2 of the present invention;

[0037] Figure 15 XRD spectrum of the ZnO / TiO2 / Ti3C2T x locally enlarged XRD spectrum of the composite material prepared in Example 2 of the present invention;

[0038] Figure 16 XRD spectrum of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 3 of the present invention;

[0039] Figure 17 XRD spectrum of the ZnO / TiO2 / Ti3C2T x locally enlarged XRD spectrum of the composite material prepared in Example 3 of the present invention;

[0040] Figure 18The curve of the reflection loss value of ZnO prepared in Comparative Example 1 of the present invention varying with frequency at different thicknesses;

[0041] Figure 19 TiO2 / Ti3C2T prepared in Comparative Example 3 of the present invention x The curve of the reflection loss value of the composite varying with frequency at different thicknesses;

[0042] Figure 20 ZnO / TiO2 / Ti3C2T prepared in Example 1 of the present invention x The curve of the reflection loss value of the composite material varying with frequency at different thicknesses;

[0043] Figure 21 ZnO / TiO2 / Ti3C2T prepared in Example 2 of the present invention x The curve of the reflection loss value of the composite material varying with frequency at different thicknesses;

[0044] Figure 22 ZnO / TiO2 / Ti3C2T prepared in Example 3 of the present invention x The curve of the reflection loss value of the composite material varying with frequency at different thicknesses. Detailed implementation manners

[0045] The present invention first provides a preparation method of a zinc oxide / titanium dioxide / titanium carbide composite absorbing material, including:

[0046] Step 1: Add Ti3C2T x nanosheets into deionized water and stir evenly. The mass ratio of the Ti3C2T x to deionized water is preferably 1:150 to obtain a Ti3C2T x nanosheet suspension. The Ti3C2T x nanosheets are prepared by the typical HF etching method of Ti3AlC2 without special limitations.

[0047] Step 2: Dissolve Zn(CH3COO)2·2H2O in methanol. The mass g of the Zn(CH3COO)2·2H2O: the volume mL of methanol is preferably 1:50, and stir for 2 - 4 h until completely dissolved to obtain a Zn(CH3COO)2·2H2O solution.

[0048] Step 3: Mix the two solutions in Step 1 and Step 2 evenly and transfer them to a sealed autoclave for reaction. The reaction temperature is preferably 160-180°C, and the reaction time is preferably 22-24 h. Centrifuge to separate the precipitate, wash it several times with deionized water and ethanol, and perform freeze-drying treatment for 40-50 h. The freeze-drying pressure is preferably 0.1 Pa, and then perform heat treatment under argon protection. The heat treatment temperature is preferably 600-700°C, and the time is preferably 2-3 h to obtain the composite electromagnetic wave absorbing material. The Ti3C2T x The mass ratio of the MXene powder to Zn(CH3COO)2·2H2O is preferably (0.02-0.4):1.

[0049] The present invention also provides the zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave-absorbing material obtained by the above preparation method. The composite wave-absorbing material has a rose-like, sandwich-like hamburger-shaped or spiny sea urchin-like structure.

[0050] The following further describes the present invention in detail with specific examples. Except for Ti3C2T x in the raw materials involved in the examples, the others are all commercially available.

[0051] Example 1: A zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave-absorbing material (1) is prepared according to the following steps:

[0052] Step 1: Add 0.02 g of Ti3C2T x MXene (prepared by the typical HF etching method) to 3 ml of deionized water and disperse it evenly.

[0053] Step 2: Dissolve 1 g of Zn(CH3COO)2·2H2O in 50 ml of methanol and stir for 2 h until completely dissolved.

[0054] Step 3: Mix the solutions obtained in Step 1 and Step 2, stir evenly and transfer them to a Teflon-sealed autoclave. The reaction temperature is 160°C and the reaction time is 24 h. Centrifuge the product to remove the supernatant, and wash the obtained precipitate several times with deionized water and ethanol. After freeze-drying in a freezer at a pressure of 0.1 Pa, treat them at 600°C for 2 h under argon protection to obtain a gray-black powder, which is the ZnO / TiO2 / Ti3C2T x MXene composite material.

[0055] Figure 4 For the ZnO / TiO2 / Ti3C2T prepared in Example 1 of the present invention xSEM image of the composite material. From the figure, it can be observed that its morphology is significantly different from that of pure ZnO, TiO2 / Ti3C2T x composites. Its morphology is relatively complex, mainly including: spherical flower shape, macaron shape combined with round cakes, hexagonal rose shape, ice cream ball shape, and hamburger shape with a filling. As can be seen from the figure, there are many micropores in this morphology, which will be beneficial to the multiple reflections and absorptions of electromagnetic waves in the material; there are many surfaces and interfaces in this morphology, which will be beneficial to the interfacial polarization loss and dipole polarization loss, and have certain advantages in improving the wave absorption performance. The formation of various morphologies is mainly related to the growth of ZnO crystals under the interference of Ti3C2T x

[0056] Figure 5 SEM micrograph of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 1 of the present invention. As can be seen from the figure, the material presents a regular hexagonal rose morphology, and the layered petals grow directly on the surface of the hexagon and along the edges of the hexagon. The formation of this morphology depends on the growth direction and speed of zinc oxide under low concentration of Ti3C2T x

[0057] Figure 12 XRD pattern of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 1 of the present invention. The vast majority of its diffraction peaks are the same as those of wurtzite ZnO. Due to the high content of ZnO, the diffraction peaks of TiO2 and Ti3C2T x are not obvious.

[0058] Figure 13 Partial enlarged XRD pattern of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 1 of the present invention. In the range of 5-30°, the peaks of the (002) and (006) planes of Ti3C2T x can be observed. In addition, there is also an obvious peak at 25.3°, which belongs to the (101) plane of TiO2. Figure 12 and 13 indicate that the obtained product is ZnO / TiO2 / Ti3C2T x composite.

[0059] Figure 20 Curves of the reflection loss values of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 1 of the present invention at different thicknesses as a function of frequency. The composite exhibits good wave absorption performance. When the matching thickness is 2.5 mm, the effective wave absorption (RL min ​​The frequency range (≤ -10 dB) can reach 1.4 GHz. When the thickness is 3 mm, the effective wave absorption frequency range is 0.59 GHz. As the sample thickness increases from 4 mm to 5 mm, the effective wave absorption frequency range increases from 1 GHz to 1.11 GHz. At 8.8 GHz, when the thickness is 2.5 mm, the minimum reflection loss can reach -31.96 dB, with the most ideal reflection loss value and effective bandwidth. The results meet the requirements of the wave absorption material for thinness and wave absorption intensity, indicating that the sample has strong electromagnetic wave absorption ability. By an experimental method, ZnO and TiO2 / Ti3C2T x are compounded to prepare a composite with a special morphology, which makes its wave absorption performance undergo a qualitative leap. The main reason is that its multiple special morphologies generate strong interfacial polarization loss and dipole polarization loss, resulting in good impedance matching and providing a complex transmission path for incident electromagnetic waves.

[0060] Example 2: A zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave absorption material (II) is prepared according to the following steps:

[0061] Step 1: Add 0.15 g of Ti3C2T x MXene (prepared by a typical HF etching method) to 22.5 ml of deionized water and disperse it evenly.

[0062] Step 2: Dissolve 1 g of Zn(CH3COO)2·2H2O in 50 ml of methanol and stir for 2 h until completely dissolved.

[0063] Step 3: Mix the solutions obtained in Step 1 and Step 2, stir evenly, and transfer them to a Teflon-sealed autoclave. The reaction temperature is 160 °C and the reaction time is 24 h. Centrifuge the product to remove the supernatant, and wash the obtained precipitate several times with deionized water and ethanol. After freeze-drying in a freezer with a pressure of 0.1 Pa, treat them at 600 °C for 2 h under argon protection to obtain a gray-black powder, which is the ZnO / TiO2 / Ti3C2T x MXene composite material.

[0064] Figure 6 This is the scanning electron microscope photo of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 2 of the present invention. It can be observed from the figure that its morphology is mainly a hamburger shape with a sandwich. The formation of this morphology depends on the growth direction and speed of zinc oxide at a higher concentration of Ti3C2T x There is a certain porous structure between the hamburgers. The morphology is relatively single compared with that in Example 1, but the porous structure is still beneficial to the multiple reflections and absorptions of electromagnetic waves in the material.

[0065] Figure 14 XRD pattern of the ZnO / TiO2 / Ti3C2T composite prepared in Example 2 of the present invention. Its pattern is the same as that of Example 1, and the vast majority of its diffraction peaks are the same as those of wurtzite ZnO. Due to the relatively high content of ZnO, the diffraction peaks of TiO2 and Ti3C2T x are not obvious. x

[0066] Figure 15 XRD partial enlarged pattern of the ZnO / TiO2 / Ti3C2T composite prepared in Example 2 of the present invention. Its pattern is the same as that of Example 1. In the range of 5 - 30°, the peaks of the (002) and (006) planes of Ti3C2T x can be observed. In addition, there is also an obvious peak at 25.3°, which belongs to the (101) plane of TiO2. The intensity of the TiO2 diffraction peak is enhanced compared with that of Example 1, indicating that the obtained product is ZnO / TiO2 / Ti3C2T x composite. x

[0067] Figure 21 Curve of the reflection loss value of the ZnO / TiO2 / Ti3C2T composite prepared in Example 2 of the present invention varying with frequency at different thicknesses. When the sample thicknesses are 2.5 mm, 3 mm, 4.5 mm, and 5 mm, their effective wave absorption frequency ranges are 1.1 GHz, 0.74 GHz, 1.5 GHz, and 2.24 GHz respectively. This may be due to the increase in the content of Ti3C2T x which increases the conductive loss. When the sample thickness is 4.5 mm, the lowest reflection loss value of -29.9 dB can be obtained at 17.2 GHz, indicating that the product has a certain electromagnetic wave loss ability. By comparing with Example 1, it is found that the electromagnetic wave loss ability of the product obtained in Example 2 reaches the peak at 4.5 mm. Its thickness is higher than that of the sample in Example 1, and its strength is lower than that of the sample in Example 1. The wave absorption performance decreases with the increase in the content of Ti3C2T x , which may be because the excessive TiO2 destroys the multi - interface morphology, resulting in a worse impedance match and enhanced reflection characteristics. However, compared with Comparative Examples 1 and 3, this performance still has great advantages, once again proving that the composite with a special morphology prepared by compounding ZnO with TiO2 / Ti3C2T x can improve the wave absorption performance. x

[0068] Example 3: A zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave - absorbing material (III), which is carried out according to the following steps:

[0069] Step 1: Weigh 0.27 g of Ti3C2T​​​x MXene (prepared by a typical HF etching method) was added to 40.5 ml of deionized water and dispersed evenly.

[0070] Step 2: 1 g of Zn(CH3COO)2·2H2O was dissolved in 50 ml of methanol and stirred for 2 h until completely dissolved.

[0071] Step 3: The solutions obtained in Step 1 and Step 2 were mixed, stirred evenly, and then transferred to a Teflon-sealed autoclave. The reaction temperature was 160 °C and the reaction time was 24 h. The product was centrifuged to remove the supernatant, and the obtained precipitate was washed several times with deionized water and ethanol. After freeze-drying in a freezer under a pressure of 0.1 Pa, they were treated at 600 °C for 2 h under argon protection to obtain a gray-black powder, which was ZnO / TiO2 / Ti3C2T x MXene composite material.

[0072] Figure 7 is the scanning electron microscope photograph of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 3 of the present invention. It can be observed from the figure that its morphology is mainly a spiny sea urchin-like structure, and the formation of this morphology depends on the growth direction and speed of zinc oxide under a high concentration of Ti3C2T x As can be seen from the figure, the porous structure of this morphology is significantly reduced, and the number of surfaces and interfaces also decreases sharply, which may have an adverse effect on the wave absorption performance.

[0073] Figure 16 is the XRD pattern of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 3 of the present invention. Its pattern is the same as that of Examples 1 and 2, and the vast majority of diffraction peaks are the same as those of wurtzite ZnO. Due to the high content of ZnO, the diffraction peaks of TiO2 and Ti3C2T x are not obvious.

[0074] Figure 17 is the enlarged local XRD pattern of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 3 of the present invention. Its pattern is the same as that of Examples 1 and 2. In the range of 5-30°, the peaks of the (002) and (006) planes of Ti3C2T x can be observed. In addition, there is also an obvious peak at 25.3°, which belongs to the (101) plane of TiO2. The intensity of the TiO2 diffraction peak is enhanced compared with that of Examples 1 and 2, indicating that the obtained product is ZnO / TiO2 / Ti3C2T x composite.

[0075] Figure 22 is the ZnO / TiO2 / Ti3C2T prepared in Example 3 of the present inventionx The curve of the reflection loss value of the composite material at different thicknesses changing with frequency is shown. It can be seen that before the thickness reaches 4.5 mm, the sample does not produce effective electromagnetic wave absorption. At a thickness of 4.5 mm, the minimum loss value of -28.3 dB is obtained at 18.18 GHz, and the effective frequency absorption range is only 1.34 GHz. The decline in wave absorption performance may be due to the excessive presence of TiO2 and Ti3C2T x which destroys the multi-interface morphology, resulting in poor impedance matching and relatively strong reflection characteristics.

[0076] Example 4: Preparation of a zinc oxide / titanium dioxide / titanium carbide (Ti3C2T x MXene) composite wave-absorbing material (IV), which is carried out according to the following steps:

[0077] Step 1: Add 0.4 g of Ti3C2T x MXene (prepared by the typical HF etching method) to 60 ml of deionized water and disperse it evenly.

[0078] Step 2: Dissolve 1 g of Zn(CH3COO)2·2H2O in 50 ml of methanol and stir for 2 h until completely dissolved.

[0079] Step 3: Mix the solutions obtained in Step 1 and Step 2, stir evenly, and transfer them to a Teflon-sealed autoclave. The reaction temperature is 160 °C and the reaction time is 24 h. Centrifuge the product to remove the supernatant, and wash the obtained precipitate with deionized water and ethanol several times. After freeze-drying in a freezer at a pressure of 0.1 Pa, treat them at 600 °C for 2 h under argon protection to obtain a gray-black powder, which is the ZnO / TiO2 / Ti3C2T x MXene composite material.

[0080] Figure 8 The scanning electron microscope photograph of the ZnO / TiO2 / Ti3C2T x composite material prepared in Example 4 of the present invention. It can be observed from the figure that its morphology is the same as that in Example 3, mainly a sea urchin-like structure with thorns. This result indicates that when the mass of Ti3C2T x reaches 0.12, it has reached the upper limit, and the morphology no longer changes after exceeding this mass.

[0081] Comparative Example 1: Preparation of a pure ZnO wave-absorbing material, which is carried out according to the following steps:

[0082] Step 1: Dissolve 1 g of Zn(CH3COO)2·2H2O in 50 ml of methanol and stir for 2 h until completely dissolved.

[0083] Step 2: Transfer the solution obtained in Step 1 to a Teflon-sealed autoclave. The reaction temperature is 160 °C and the reaction time is 24 h. Centrifuge the product to remove the supernatant, and wash the obtained precipitate several times with deionized water and ethanol. After freeze-drying in a freezer under a pressure of 0.1 Pa, treat them at 600 °C for 2 h under argon protection to obtain a white powder, which is the pure ZnO wave-absorbing material.

[0084] Figure 1 This is the SEM photograph of ZnO prepared in Comparative Example 1 of the present invention. It can be observed from the figure that its morphology is circular particles, adhered to each other, the overall surface is rough, and there are fewer pores.

[0085] Figure 9 This is the XRD pattern of ZnO prepared in Comparative Example 1 of the present invention. This pattern is consistent with the typical hexagonal wurtzite structure of ZnO indexed in the ICDD database (01-089-0510), indicating that the product obtained under this condition is zinc oxide with a hexagonal wurtzite structure.

[0086] Figure 18 This is the curve of the reflection loss value of ZnO prepared in Comparative Example 1 of the present invention varying with frequency at different thicknesses. It can be seen that in the range of 1.0 - 5.5 mm thickness, the RL min value of pure zinc oxide is far from the specified effective absorption (RL min ≤ -10 dB), indicating that pure zinc oxide prepared by the hydrothermal method has no effective absorption of electromagnetic waves.

[0087] Comparative Example 2: Preparation of a TiO2 / Ti3C2T x composite material is carried out according to the following steps:

[0088] Step 1: Add 0.4 g of Ti3C2T x MXene (prepared by the typical HF etching method) to 60 ml of deionized water and disperse it evenly.

[0089] Step 2: Transfer the solution obtained in Step 1 to a Teflon-sealed autoclave, control the temperature at 160 °C, and the reaction time is 24 h. Centrifuge the prepared precipitate, wash it alternately with deionized water and ethanol several times, and then dry the product in a vacuum oven at 60 °C for 12 h to obtain a black powder-like TiO2 / Ti3C2T x composite.

[0090] Figure 2 This is the SEM photograph of the TiO2 / Ti3C2T x composite prepared in Comparative Example 2 of the present invention. It can be observed from the figure that its morphology is an accordion-like multi-layer structure, which is different from that of pure Ti3C2T xThe morphology is consistent, indicating that the hydrothermal reaction stage has no effect on its morphology.

[0091] Figure 10 This is the XRD pattern of the TiO2 / Ti3C2T prepared in Comparative Example 2 of the present invention. x In the figure, the diffraction peaks at 25.3°, 37°, 48.07°, and 53.82° correspond to the diffraction peaks of anatase TiO2 (JCPDS 21-1272), and the diffraction peaks at ~8.5°, 27.51°, and 36.30° correspond to the (002), (006), and (008) crystal planes of Ti3C2T. x This indicates that the structure of the intermediate product without high-temperature treatment is the TiO2 / Ti3C2T composite, and part of Ti3C2T has been oxidized to TiO2. x complex. x Some of it has been oxidized to TiO2.

[0092] Comparative Example 3: The preparation of a TiO2 / Ti3C2T composite material is carried out according to the following steps: x Step 1: Add 0.4 g of Ti3C2T MXene (prepared by the typical HF etching method) to 60 ml of deionized water and disperse it evenly.

[0093] Step 2: Transfer the solution obtained in Step 1 to a Teflon-sealed autoclave, control the temperature at 160 °C, and the reaction time is 24 h. Centrifuge the prepared precipitate, wash it alternately with deionized water and ethanol several times, then place the product in a vacuum oven at 60 °C and dry it for 12 h. Then put the product into a tube furnace with argon protection and calcine it at 600 °C for 2 h to obtain a black powder-like TiO2 / Ti3C2T x complex.

[0094] This is the SEM photograph of the TiO2 / Ti3C2T composite prepared in Comparative Example 3 of the present invention. It can be observed from the figure that its morphology is no longer the accordion-like multi-layer structure but changes to a block structure where fragments are interconnected. x complex.

[0095] Figure 3 This is the XRD pattern of the TiO2 / Ti3C2T composite prepared in Comparative Example 3 of the present invention. Its pattern is similar to the XRD pattern of the intermediate product TiO2 / Ti3C2T x complex, indicating that after hydrothermal reaction and high-temperature treatment, the product structure is still the TiO2 / Ti3C2T

[0096] Figure 11 This is the XRD pattern of the TiO2 / Ti3C2T composite prepared in Comparative Example 3 of the present invention. Its pattern is similar to the XRD pattern of the intermediate product TiO2 / Ti3C2T x complex, indicating that after hydrothermal reaction and high-temperature treatment, the product structure is still the TiO2 / Ti3C2T x complex. x After hydrothermal reaction and high-temperature treatment, the product structure is still the TiO2 / Ti3C2T x complex.

[0097] Figure 19 The TiO2 / Ti3C2T prepared in Comparative Example 3 of the present invention x Variation curve of the reflection loss value of the composite at different thicknesses with frequency. When the thickness is 2.0 mm, the effective wave absorption (RL min ≤ -10 dB) frequency range is as narrow as 0.3 GHz. As the thickness of the sample increases, the effective wave absorption frequency range reaches the widest 0.85 GHz at 5.0 mm. When the thickness is 5.0 mm, the composite material reaches the lowest RL value of -28.4 dB at 15.3 GHz.

Claims

1. A preparation method of a zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material, characterized in that, Including: Step 1: Add Ti3C2T x nanosheets into deionized water and stir evenly to obtain a Ti3C2T x nanosheet suspension; Step 2: Dissolve Zn(CH3COO)2·2H2O in methanol to obtain a Zn(CH3COO)2·2H2O solution; Step 3: Mix the Ti3C2T x nano-sheet suspension with the Zn(CH3COO)2·2H2O solution in Step 2, transfer the mixture to a Teflon-sealed autoclave for reaction, and after centrifugation, washing, and freeze-drying, perform heat treatment in a tube furnace under an argon atmosphere to obtain a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material; the composite microwave absorbing material has a rose-shaped, sandwiched hamburger-shaped, or spiny sea urchin-shaped structure; In the said Step 3, the reaction temperature is 160 - 180 °C and the reaction time is 22 - 24 h; In the third step described above, the mass ratio of Ti3C2T x to Zn(CH3COO)2·2H2O is (0.02 - 0.4):

1.

2. The preparation method of a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material according to claim 1, characterized in that, In the first step described above, the mass ratio of Ti3C2T x nanosheets to deionized water is 1:

150.

3. The preparation method of a zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material according to claim 1, characterized in that, In the said Step 2, the mass of Zn(CH3COO)2·2H2O in g: the volume of methanol in mL is 1:

50.

4. The preparation method of a zinc oxide / titanium dioxide / titanium carbide composite microwave absorbing material according to claim 1, characterized in that, In the said Step 3, the freeze-drying time is 40 - 50 h and the pressure is 0.1 - 0.2 Pa.

5. The preparation method of a zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material according to claim 1, characterized in that, In the said Step 3, the heat treatment temperature is 600 - 700 °C and the time is 2 - 3 h.

6. The zinc oxide / titanium dioxide / titanium carbide composite wave-absorbing material obtained by the preparation method according to Claim 1, wherein the composite wave-absorbing material has a rose shape, a sandwiched hamburger shape or a spiny sea urchin shape.

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