Preparation method and application of crystalline-amorphous heterostructure composite material

Abstract

The invention provides a preparation method and application of a crystalline / amorphous heterostructure composite material, and relates to the field of electromagnetic wave absorption, conversion and protection of nano composite materials. According to the invention, the micro-aerobic non-crystallization treatment of ammonium persulfate is adopted to controllably induce the Ti < 3 > C < 2 > T < x > MXene nanosheet with good crystallinity to be partially converted into a disordered amorphous state in situ, so that the components are irreversibly transformed from an ordered crystalline state to the disordered amorphous state, and a rich and uniform crystalline state / amorphous state heterogeneous interface structure is formed in the MXene nanosheet. An interface electron transfer channel is formed between the constructed crystalline region and the amorphous region through interface chemical bonds, and strong interface interaction is promoted. The dielectric polarization response of the MXene nanosheet is obviously optimized due to the formation of abundant crystalline / amorphous heterogeneous interfaces, strong interface polarization loss is generated, and effective conversion of electromagnetic wave energy is promoted.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic microwave absorption of nanocomposite materials, specifically to a method for preparing and applying a crystalline-amorphous heterostructure composite material. Background Technology

[0002] The widespread use of wireless communication devices has significantly improved people's quality of life and work efficiency. However, with the rapid development of electromagnetic technology, electromagnetic radiation generated by electronic devices is becoming the fourth largest environmental pollution problem facing humanity. Long-term exposure to or working in high-intensity electromagnetic radiation environments not only poses potential harm to human health and the ecological environment but also affects the reliability and normal operation of precision electronic equipment. Simultaneously, advancements in military radar detection technology have increased the risk of detection for advanced defense equipment, directly impacting its battlefield survivability. This places higher demands on the stealth performance of weaponry, as traditional stealth methods are no longer sufficient to meet the needs of complex electromagnetic environments and advanced detection technologies. Therefore, there is an urgent need to develop electromagnetic functional materials that can effectively convert unwanted electromagnetic waves and radar detection microwaves within composite materials, achieving efficient control of electromagnetic pollution and the stealth capabilities of defense weaponry. Electromagnetic wave absorbing materials include magnetic materials and dielectric materials. However, magnetic absorbers suffer from high density, narrow absorption bandwidth, and low response frequency, limiting their application in electromagnetic wave absorption and protection. Dielectric materials, due to their stable physicochemical properties and tunable electronic structure, have attracted widespread attention. Therefore, the development of high-performance dielectric electromagnetic wave absorbing materials has potential applications in electromagnetic pollution and radar stealth. Based on this, this invention provides a method for preparing and applying a crystalline-amorphous heterostructure composite material. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a crystalline / amorphous heterostructure composite material, its preparation method, and its application, solving the technical problems of low absorption intensity, poor impedance matching, and narrow response band in current dielectric electromagnetic wave absorbing materials.

[0004] The crystalline / amorphous heterostructure composite material constructed in this invention has abundant heterostructure interfaces, which improves the dielectric polarization response range of the material. At a thickness of 2.5 mm, the minimum reflection loss reaches -52.9 dB.

[0005] On the one hand, such as Figures 1-2 As shown, this invention provides a crystalline / amorphous heterostructure composite material, wherein the crystalline / amorphous heterostructure composite material is A / C-MXene, comprising a highly crystalline two-dimensional transition metal carbide T3C2T induced by the strong oxidizing properties of ammonium persulfate. xMXene nanosheets undergo a controllable micro-oxygen amorphization transformation process to form nanocomposite materials with crystalline / amorphous heterostructures.

[0006] This crystalline / amorphous heterostructure is achieved by disrupting the ordered crystalline structure of MXene nanosheets with the strong oxidizing power of ammonium persulfate, forming a disordered crystalline structure. Ammonium persulfate is used as a strong oxidant to perform micro-oxygen amorphization treatment on multilayer MXene, constructing a crystalline / amorphous heterostructure interface, enhancing the dielectric polarization response of MXene nanosheets, and promoting the absorption and conversion of electromagnetic waves.

[0007] On the other hand, such as Figure 3 As shown, the present invention also provides a method for preparing a crystalline / amorphous heterostructure composite material, the steps of which include: S1. Two-dimensional layered transition metal carbide MAX phase Ti3AlC2 raw material is added to hydrofluoric acid etching solution and reacted under water bath conditions. After etching is completed, it is centrifuged, washed with water and freeze-dried to obtain accordion-shaped multilayer MXene powder. S2. The MXene powder prepared in step S1 is added to an ammonium persulfate aqueous solution for micro-oxygen amorphization treatment. After stirring and reacting fully, the mixture is centrifuged, washed with water, and freeze-dried to obtain the crystalline / amorphous heterostructure composite material A / C-MXene.

[0008] Further, in step S1, the amount of Ti3AlC2 raw material is 1-3g; the hydrofluoric acid etching solution is prepared by adding 5-10mL of hydrofluoric acid solution to 10-40mL of 8-12mol / L hydrochloric acid solution.

[0009] Furthermore, the reaction temperature is 35~50℃, the reaction time is 24~72h, and the mixture is washed with water until the pH is 6~7.

[0010] Furthermore, in step S1, the freeze-drying temperature is -55±5℃ and the time is 24±1h.

[0011] Further, in step S2, the mass of MXene powder is 0.05-0.5g, the concentration of ammonium persulfate is 0.05-0.2mol / L, and the solution volume is 30-100mL.

[0012] Furthermore, in step S2, the reaction time is 30-72 hours, and the mixture is washed with water until the pH is approximately 6-7.

[0013] Furthermore, in step S2, the freeze-drying temperature is -55±5℃ and the time is 24±1h.

[0014] Furthermore, the micro-oxygen amorphization treatment time in step S2 is 0-48 hours.

[0015] On the other hand, the present invention also provides the crystalline / amorphous heterostructure composite material or preparation method to enhance the dielectric polarization response capability of MXene nanosheets, which can be applied to the absorption and / or conversion of electromagnetic waves.

[0016] This invention provides a method for preparing and applying crystalline / amorphous heterostructure composite materials. Compared with existing technologies, it has the following advantages: The crystalline / amorphous heterostructure composite material provided by this invention first forms an accordion-shaped multilayer Ti3C2T structure by etching a Ti3AlC2MAX phase precursor with hydrofluoric acid. x MXene structure was first constructed; then, the strong oxidizing property of ammonium persulfate was used to controllably induce micro-oxygen amorphization in MXene, irreversibly transforming some of the well-crystallized crystalline structures into amorphous structures. This resulted in abundant crystalline / amorphous heterojunctions within the MXene nanosheets. This change in the crystallinity of the localized crystalline structure led to differences in the dielectric properties of the materials on both sides of the heterostructure, causing electron migration and rearrangement at the interface, forming a space charge region. Under the influence of an alternating electromagnetic field, the charge-hole pairs at the interface underwent orientation polarization. Due to the constrained electron migration at the interface, the dielectric polarization response lags behind the frequency of the applied electric field change, resulting in polarization relaxation. This enhances the dielectric polarization response capability of the MXene material, generating strong interfacial polarization loss and promoting efficient conversion of electromagnetic wave energy. Furthermore, the amorphous structure formed by in-situ micro-oxygen reconstruction optimizes the impedance matching of the MXene surface, promoting the entry of electromagnetic waves into the absorber. In addition, the amorphous component formed by in-situ transformation in this invention avoids the problem of uneven nanomaterial distribution caused by traditional in-situ growth methods. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 Scanning electron microscope (SEM) images (a, b) of a crystalline / amorphous heterostructure composite material A / C-MXene provided in an embodiment of the present invention. Figure 2 Transmission electron microscopy (TEM) images (a, b) of a crystalline / amorphous heterostructure composite material A / C-MXene provided for an embodiment of the present invention. Figure 3This is a schematic flowchart illustrating a method for preparing a crystalline / amorphous heterostructure composite material according to an embodiment of the present invention. Figure 4 The following are performance diagrams of crystalline / amorphous heterostructures of A / C-MXene-3h-0.1 (a), A / C-MXene-6h-0.1 (b), A / C-MXene-9h-0.1 (c), and A / C-MXene-15h-0.1 (d) provided for embodiments of the present invention. Figure 5 The following are performance diagrams of crystalline / amorphous heterostructures of A / C-MXene-24h-0.1 (a) and A / C-MXene-48h-0.1 (b) provided for embodiments of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To better understand the above technical solution, a detailed description of the technical solution will be provided below in conjunction with the accompanying drawings and specific embodiments. The MAX phase Ti3AlC2 (200 mesh) used in this invention was purchased from Jilin Yiyi Technology Co., Ltd.

[0021] Example 1

[0022] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0023] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred at 300r / min for 3h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-3-0.1 composite material with crystalline / amorphous heterostructure interface.

[0024] like Figure 4 As shown in (a), the crystalline / amorphous heterostructure composite material A / C-MXene-3-0.1 obtained above has a minimum reflection loss of -31.97dB at a thickness of 2.0mm and an effective absorption bandwidth of 3.84GHz at a thickness of 1.5mm.

[0025] Example 2

[0026] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution and stirred for 30 min to form a strong acid etchant. 2 g of the two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etching solution and reacted at 40 °C for 30 h in a water bath. The mixture was then centrifuged and washed with water until the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0027] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred for 6h. After centrifugation and washing with water until the pH value of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-6-0.1 composite material with crystalline / amorphous heterostructure interface.

[0028] like Figure 4 As shown in (b), the crystalline / amorphous heterostructure composite material A / C-MXene-6-0.1 obtained above has a minimum reflection loss of -52.9dB at a thickness of 2.5mm and an effective absorption bandwidth of 5.28GHz at a thickness of 1.65mm.

[0029] Example 3

[0030] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0031] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred at 300r / min for 9h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-9-0.1 composite material with crystalline / amorphous heterostructure interface.

[0032] like Figure 4 As shown in (c), the crystalline / amorphous heterostructure composite material A / C-MXene-9-0.1 obtained above has a minimum reflection loss of -17.48dB at a thickness of 5.0mm and an effective absorption bandwidth of 2.64GHz at a thickness of 2.0mm.

[0033] Example 4

[0034] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0035] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred at 300r / min for 15h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-15-0.1 composite material with crystalline / amorphous heterostructure interface.

[0036] like Figure 4 As shown in (d), the crystalline / amorphous heterostructure composite material A / C-MXene-15-0.1 obtained above has a minimum reflection loss of -27.95dB at a thickness of 5.0mm and an effective absorption bandwidth of 1.68GHz at a thickness of 5.0mm.

[0037] Example 5

[0038] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0039] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred at 300r / min for 24h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-24-0.1 composite material with crystalline / amorphous heterostructure interface.

[0040] like Figure 5 As shown in (a), the crystalline / amorphous heterostructure composite material A / C-MXene-24-0.1 obtained above has a minimum reflection loss of -6.9dB at a thickness of 5.0mm.

[0041] Example 6

[0042] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0043] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.1mol / L ammonium persulfate solution and stirred at 300r / min for 48h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-48-0.1 composite material with crystalline / amorphous heterostructure interface.

[0044] like Figure 5 As shown in (b), the crystalline / amorphous heterostructure composite material A / C-MXene-48-0.1 obtained above has a minimum reflection loss of -3.7dB at a thickness of 5.0mm.

[0045] Example 7

[0046] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0047] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.05mol / L ammonium persulfate solution and stirred at 300r / min for 6h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-6-0.05 composite material with crystalline / amorphous heterostructure.

[0048] Example 8

[0049] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0050] S2. 0.15g of multilayer MXene powder was added to 60mL of 0.2mol / L ammonium persulfate solution and stirred at 300r / min for 6h. After centrifugation and washing with water until the pH of the solution reached 6.5, it was further freeze-dried at -55℃ for 24h to obtain A / C-MXene-6-0.2 composite material with crystalline / amorphous heterostructure.

[0051] Example 9

[0052] This invention provides a method for preparing a crystalline / amorphous heterostructure composite material, comprising: S1. 10 mL of hydrofluoric acid was added to 40 mL of 9 mol / L hydrochloric acid solution, and stirred at 500 rpm for 30 min to form a strong acid etchant. 2 g of a two-dimensional layered transition metal carbide MAX phase Ti3AlC2 precursor was added to the strong acid etchant solution, and reacted at 40 °C in a water bath for 30 h. After centrifugation and washing with water, the pH of the supernatant reached 6.5. Accordion-shaped multilayer MXene powder was obtained by freeze-drying at -55 °C for 24 h.

[0053] S2, 0.15g of multilayer MXene powder without ammonium persulfate solution treatment, was stirred in deionized water at 300 rpm for 6 hours, then centrifuged and washed with water. Further freeze-drying yielded a crystalline MXene composite material.

[0054] Figure 1 Scanning electron microscope (SEM) images (a, b) of the crystalline / amorphous heterostructure composite material A / C-MXene.

[0055] Figure 2 Transmission electron microscopy (TEM) images (a, b) of the crystalline / amorphous heterostructure composite material A / C-MXene.

[0056] In this embodiment of the invention, electromagnetic parameters were obtained using a vector network analyzer. Paraffin wax was uniformly mixed with a prepared crystalline / amorphous heterostructure composite material (6:4, 40wt%), and after being melted under vacuum heating, the mixture was pressed into a coaxial ring sample with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and a thickness of 2.0 mm using a mold. The electromagnetic parameters of the coaxial ring sample were tested using a vector network analyzer (AV3629D). The minimum reflection loss (RL) at different thicknesses was fitted according to the transmission line theory formula. (1) (2) in For effective input impedance, Let f be the free space impedance, εr = ε′-jε″ and μr = μ′-jμ″ represent the dielectric constant and complex permeability, respectively, f is the frequency, d is the corresponding thickness, and c is the speed of light in vacuum.

[0057] from Figure 4 The changes in the minimum reflection loss curves of the crystalline / amorphous heterostructure composite material A / C-MXene-6-0.1 (Example 2 above) at different thicknesses show that the minimum reflection loss value gradually decreases with increasing micro-oxygen amorphization. Figure 4 (a) It can be seen that after 3 hours of micro-oxygen amorphization treatment, the minimum reflection loss of MXene nanosheets with a thickness of 2.0 mm is -31.97 dB. Figure 4(b) It can be seen that further increasing the amorphization degree of MXene results in the construction of a crystalline / amorphous heterostructure composite material A / C-MXene-6-0.1 with abundant heterointerfaces, improving the dielectric polarization response range of the material. At a thickness of 2.5 mm, the minimum reflection loss reaches -52.9 dB. Figure 4 (c,d) and Figure 5 As can be seen from (a,b), the electromagnetic wave absorption performance of the prepared A / C-MXene composite material gradually decreases as the amorphization treatment time is further extended, from -52.9dB to -3.7dB.

[0058] The excellent electromagnetic microwave absorption performance of the A / C-MXene crystalline / amorphous heterostructure composite material provided in this invention is mainly attributed to the following aspects: First, an accordion-shaped multilayer Ti3C2T precursor was formed by etching the Ti3AlC2 MAX phase precursor with hydrofluoric acid. x MXene structure was then subjected to controlled micro-oxygen amorphization using the strong oxidizing properties of ammonium persulfate, irreversibly transforming some well-crystallized crystalline structures into amorphous ones. This resulted in abundant crystalline / amorphous heterojunctions within the MXene nanosheets. The difference in crystallinity of these localized crystalline structures led to variations in the dielectric properties of the materials on either side of the heterostructure, causing electron migration and rearrangement at the interface, forming a space charge region. Under an alternating electromagnetic field, charge-hole polarization occurred at the interface. Due to the constrained electron migration at the interface, the dielectric polarization response lags behind the frequency of the applied electric field, resulting in polarization relaxation. This enhances the dielectric polarization response of the MXene material, generating strong interfacial polarization loss and promoting efficient electromagnetic wave energy conversion. Furthermore, the amorphous structure formed by in-situ micro-oxygen reconstruction optimized the impedance matching of the MXene surface, facilitating the penetration of electromagnetic waves into the absorber.

[0059] Secondly, the embodiments of the present invention employ a micro-oxygen amorphization-induced surface reconstruction strategy to prepare crystalline / amorphous heterostructure composite materials, which exhibit excellent minimum reflection loss and effective absorption bandwidth.

[0060] Finally, this invention focuses on multilayer MXene as the research object, and prepares composite materials with crystalline / amorphous heterostructures through a micro-oxygen amorphization-induced MXene nanosheet surface reconstruction strategy. This research utilizes low-cost raw materials, simple equipment and preparation processes, and is safe, clean, and environmentally friendly, facilitating large-scale industrial production.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A crystalline / amorphous heterostructure composite material, characterized in that, The crystalline / amorphous heterostructure composite material is A / C-MXene, comprising a highly crystalline two-dimensional transition metal carbide T3C2T induced by the strong oxidizing properties of ammonium persulfate. x MXene nanosheets undergo a controllable micro-oxygen amorphization transformation process to form nanocomposite materials with crystalline / amorphous heterostructures.

2. The method for preparing a crystalline / amorphous heterostructure composite material as described in claim 1, characterized in that the step... include: S1. Add the two-dimensional layered transition metal carbide MAX phase Ti3AlC2 raw material to the hydrofluoric acid etching solution and react at 400-600 r / min under water bath conditions. After etching, centrifuge, wash with water and freeze dry to obtain accordion-shaped multilayer MXene powder. S2. The MXene powder prepared in step S1 is added to an ammonium persulfate aqueous solution for micro-oxygen amorphization treatment and stirred at 300-500 r / min. After the reaction is complete, the mixture is centrifuged, washed with water and freeze-dried to obtain the crystalline / amorphous heterostructure composite material A / C-MXene.

3. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, In step S1, the Ti3AlC2 raw material is 1-3g; the hydrofluoric acid etching solution is prepared by adding 5-10mL of hydrofluoric acid solution to 10-40mL of 8-12mol / L hydrochloric acid solution.

4. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, The reaction temperature is 35~50℃, the reaction time is 24~72h, and the solution is washed with water until the pH is 6~7.

5. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, In step S1, the freeze-drying temperature is -55±5℃ and the time is 24±1h.

6. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, In step S2, the mass of MXene powder is 0.05-0.5g, the concentration of ammonium persulfate is 0.05-0.2mol / L, and the solution volume is 30-100mL.

7. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, The reaction time in step S2 is 30-72 hours, and the water is washed until the pH is about 6-7.

8. The method for preparing a crystalline / amorphous heterostructure composite material according to claim 2, characterized in that, In step S2, the freeze-drying temperature is -55±5℃ and the time is 24±1h.

9. The crystalline / amorphous heterostructure composite material of claim 1 or the preparation method of any one of claims 2-8 enhances the dielectric polarization response of MXene nanosheets and is applied to the absorption and / or conversion of electromagnetic waves.

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