An accordion-like Ti3C2Tx MXene composite material, its preparation method and application

Abstract

The present invention discloses an accordion-like Ti3C2Tx MXene composite material, a preparation method and an application thereof, which relate to the technical field of electromagnetic microwave absorption. First, an accordion-like powder is prepared by acid etching, and then layered cobalt-nickel hydroxide is hydrothermally grown between the layers and at the edges of the powder. Further, with the assistance of melamine, nitrogen-doped carbon nanotubes are epitaxially grown using cobalt-nickel hydroxide as a metal catalytic source, and the Ti3C2Tx MXene composite material is prepared. The 2D-1D-2D conductive network formed between the layers in this application improves the conduction loss of the material. The heteroatom doping and the formed hetero-interfaces significantly optimize the dielectric polarization relaxation process of the material, achieving an effective balance between conduction loss and dielectric polarization; and the optimized impedance matching and strong electromagnetic wave attenuation ability endow the composite material with excellent electromagnetic microwave absorption performance at a low filler content.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic microwave absorption, and particularly relates to an accordion-shaped Ti3C2Tx MXene composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of electromagnetic detection technology, electromagnetic information technology confrontation and stealth penetration of weaponry have become the key to victory in modern warfare. Mastering the stealth technology of weaponry plays an important role in realizing modern national defense. In addition, the widespread application of high-frequency electromagnetic functional devices brings convenience to people's lives while also facing problems such as physical diseases caused by electromagnetic radiation. Exploring and developing broadband lightweight electromagnetic wave absorption materials can effectively absorb the energy of electromagnetic waves, which is an effective way to reduce the detectability of targets, achieve the defense stealth of weaponry, and prevent electromagnetic radiation pollution.

[0003] Magnetic metals and ferrites, as typical magnetic absorption materials, are commonly used to improve magnetic loss and reduce the matching thickness. Due to their inevitable high density and inherent impedance mismatch, the widespread application of magnetic materials in the field of electromagnetic wave absorption is hindered. Effectively combining carbon materials with magnetic materials to construct a dielectric-magnetic loss synergistic double-loss mechanism is an effective way to explore broadband lightweight electromagnetic wave absorption materials. In view of this, it is necessary to develop a nano-composite material with high electromagnetic microwave absorption performance. Summary of the Invention

[0004] The purpose of the present invention is to provide an accordion-shaped Ti3C2Tx MXene composite material, a preparation method thereof, and an application thereof, and solve the following technical problems:

[0005] The existing multi-layer MXene-based electromagnetic microwave absorption materials have low absorption performance.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of an accordion-shaped Ti3C2Tx MXene composite material includes the following steps:

[0008] S1. Add Ti 3 AlC 2 to an etching solution, carry out a heat preservation reaction, centrifuge, wash with water, and freeze-dry to obtain a powder;

[0009] S2. Disperse the powder obtained in step S1 in a solution, add mixed transition metal ions and hexamethylenetetramine, carry out a heat preservation reaction, wash with water, centrifuge, and freeze-dry to obtain a composite material;

[0010] S3. Place the composite material and melamine obtained in step S2 in a reactor, heat and react under a nitrogen atmosphere, and cool to room temperature to obtain an accordion-like Ti3C2Tx MXene composite material with adjustable interlayer spacing. 3 C 2 T X MXene composite material.

[0011] As a further aspect of the present invention: The water washing in S1 specifically is: Wash until the pH of the upper layer liquid reaches 6 - 7; The freeze-drying specifically is: At -60°C to -50°C, dry for 20 - 30 h.

[0012] As a further aspect of the present invention: The preparation method of the etching solution:

[0013] (1) Mix 20 - 40 mL of 9 - 12 mol / L hydrochloric acid solution and 1 - 5 mL of hydrofluoric acid to obtain a mixed solution;

[0014] (2) Mix the mixed solution obtained in step (1) with 1 - 2.4 g of lithium fluoride to obtain the etching solution.

[0015] As a further aspect of the present invention: The heat preservation reaction in step S1 specifically is: The reaction temperature is 35 - 45°C, and under the heat preservation condition, continuously stir for 24 - 48 h.

[0016] As a further aspect of the present invention: The solution in S2 is obtained by mixing deionized water and absolute ethanol in any ratio.

[0017] As a further aspect of the present invention: The mixed transition metal ions in step S2 are obtained by mixing Co metal ions and Ni metal ions, and the addition amounts of the Co metal ions, Ni metal ions, hexamethylenetetramine, and powder are 2 - 8 mmol: 4 - 16 mmol: 10 - 40 mmol: 100 - 300 mg. 2+ metal ions and 2+ Ni 2+ metal ions, 2+ Ni metal ions, hexamethylenetetramine, and the powder are 2 - 8 mmol: 4 - 16 mmol: 10 - 40 mmol: 100 - 300 mg.

[0018] As a further aspect of the present invention: The heat preservation reaction in step S2 specifically is: Under the water bath condition, heat up to 80 - 90°C, and carry out the heat preservation reaction for 4 - 8 h.

[0019] As a further aspect of the present invention: The mass ratio of the composite material to melamine in step S3 is 1:1 - 10.

[0020] As a further aspect of the present invention: The heat preservation reaction in step S3 specifically is: Heat up to 650 - 750°C, carry out the heat preservation reaction for 1 - 3 h, and the heating rate and the cooling rate are both 1 - 3°C / min.

[0021] An accordion-like Ti3C2Tx MXene composite material is made by the above preparation method.

[0022] Application of accordion-like Ti3C2Tx MXene composite material, which is applied in the field of electromagnetic microwave absorption.

[0023] Advantages of the present invention:

[0024] In the present invention, powders are first prepared by acid etching. The powders are accordion-like Ti3C2Tx MXene. Subsequently, the powders are mixed and reacted with transition metal ions and hexamethylenetetramine, and layered cobalt-nickel hydroxide is in-situ grown between the powder layers and at the edges. Finally, nitrogen-doped carbon nanotube arrays are epitaxially grown with melamine providing nitrogen source and carbon source and cobalt-nickel hydroxide as the catalytic source, obtaining an accordion-like Ti3C2Tx MXene composite material with adjustable layer spacing. In this application, by adjusting the amount of the added carbon source, the length and number of nitrogen-doped carbon nanotubes are effectively controlled, and further, the layer spacing of the accordion-like Ti3C2Tx MXene nanosheets is effectively enlarged, thereby forming a Ti3C2Tx MXene composite material with adjustable layer spacing. The unique carbon nanotubes in this application are anchored between the Ti3C2Tx MXene layers to form a 2D-1D-2D conductive network, improving the conduction loss of the composite material. At the same time, heteroatom doping and the formed hetero-interfaces significantly optimize the dielectric polarization relaxation process of the composite material, achieving an effective balance between conduction loss and dielectric polarization. Finally, the optimized impedance matching and strong electromagnetic wave attenuation ability endow the composite material with excellent electromagnetic microwave absorption performance at a low filler content. Description of the drawings

[0025] The present invention will be further described below with reference to the drawings.

[0026] Figure 1 Schematic diagram of the preparation process of an accordion-like Ti3C2Tx MXene composite material of the present invention;

[0027] Figure 2 Scanning electron microscope images of the accordion-like Ti3C2Tx MXene composite materials prepared in Examples 1-3 of the present invention;

[0028] Figure 3 Transmission electron microscope images of the accordion-like Ti3C2Tx MXene composite materials prepared in Examples 1-3 of the present invention;

[0029] Figure 4 Schematic diagram of the layer spacing of the accordion-like Ti3C2Tx MXene composite materials prepared in Examples 1-3 of the present invention;

[0030] Figure 5 Scanning electron microscope images of the accordion-like Ti3C2Tx MXene composite material prepared in Comparative Example 1 of the present invention;

[0031] Figure 6 Electromagnetic wave absorption performance diagram of the accordion-like Ti3C2Tx MXene composite material prepared in Examples 1-3 of the present invention;

[0032] Figure 7 Electromagnetic wave absorption performance diagram of the composite material without annealing treatment prepared in Example 4 and the composite material with annealing treatment prepared in Example 5 of the present invention. Detailed implementation manners

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1:

[0035] Please refer to Figure 1-6 , a preparation method of an accordion-like Ti 3 C 2 T X MXene composite material, including the following steps:

[0036] S1. Add 1.6 g of lithium fluoride to a mixed solution containing 25 ml of 9 mol / L hydrochloric acid aqueous solution and 5 ml of hydrofluoric acid, then continue to add 1.2 g of Ti 3 AlC 2 , heat to 40 °C, keep warm and continuously stir for 24 h, wash repeatedly, centrifuge with deionized water for multiple times until the pH of the supernatant is 6-7, freeze-dry for 24 h to obtain a powder, and store it in vacuum;

[0037] S2. After mixing 37.5 ml of deionized water and 12.5 ml of absolute ethanol solution, add 200 mg of the powder, then continue to add 4 mmol of Co(NO 3 ) 2 ˙6H 2 O, 8 mmol of Ni(NO 3 ) 2 ˙6H 2 O, 20 mmol of hexamethylenetetramine, heat to 85 °C, keep warm and react for 6 h; wash, centrifuge, and freeze-dry to obtain a composite material;

[0038] S3. Place 0.2 g of the composite material prepared in step S2 and 1 g of melamine in a tube furnace, in N 2Under the atmosphere, heat up to 700 °C, keep the temperature for pyrolysis for 2 h, and the heating and cooling rates are both 2 °C / min. Cool to room temperature to obtain accordion-shaped Ti 3 C 2 T X MXene composite material.

[0039] Please refer to Figure 6 Figure (a) in 3 C 2 T X For the MXene composite material prepared in this example, the minimum reflection loss reaches -55.8 dB at a thickness of 2.3 mm, and the effective absorption bandwidth covers the Ku-band (12.4 - 18 GHz).

[0040] Example 2:

[0041] Please refer to Figure 1-6 , a preparation method of an accordion-shaped Ti 3 C 2 T X MXene composite material, comprising the following steps:

[0042] S1. Add 1.6 g of lithium fluoride to a mixed solution containing 25 ml of 9 mol / L hydrochloric acid aqueous solution and 5 ml of hydrofluoric acid, then continue to add 1.2 g of Ti 3 AlC 2 , heat up to 40 °C, keep the temperature and continuously stir for 24 h, wash repeatedly, centrifuge with deionized water for multiple times until the pH of the supernatant is 6 - 7, and freeze-dry for 24 h to obtain a powder, which is stored in vacuum;

[0043] S2. After mixing 37.5 ml of deionized water and 12.5 ml of absolute ethanol solution, add 200 mg of the powder, then continue to add 4 mmol of Co(NO 3 ) 2 ˙6H 2 O, 8 mmol of Ni(NO 3 ) 2 ˙6H 2 O, and 20 mmol of hexamethylenetetramine, heat up to 85 °C, and keep the temperature for reaction for 6 h; wash with water, centrifuge, and freeze-dry to obtain a composite material;

[0044] S3. Place 0.2 g of the composite material prepared in step S2 and 0.2 g of melamine in a tube furnace. Under the N 2 atmosphere, heat up to 700 °C, keep the temperature for pyrolysis for 2 h, and the heating and cooling rates are both 2 °C / min. Cool to room temperature to obtain an accordion-shaped Ti 3 C 2 T X MXene composite material.

[0045] See also Figure 6 Figure (b) shows the Ti prepared in this example. 3 C 2 T X The minimum reflection loss of MXene composite materials reaches -21.6dB, and the effective absorption bandwidth is 1.92GHz.

[0046] Embodiment 3:

[0047] See also Figure 1-6 , an accordion-shaped 3 C 2 T X The preparation method of MXene composite material comprises the following steps:

[0048] S1. Add 1.6 g lithium fluoride to a mixed solution containing 25 ml 9 mol / L hydrochloric acid and 5 mL hydrofluoric acid, and then add 1.2 g Ti 3 AlC 2 , raise the temperature to 40°C, keep warm and stir continuously for 24 hours, wash repeatedly, centrifuge with deionized water several times until the pH of the supernatant is 6-7, freeze-dry for 24 hours to obtain powder, and store in vacuum;

[0049] S2, add 200 mg of powder to a mixed solution of 37.5 mL of deionized water and 12.5 mL of anhydrous ethanol, and then add 4 mmol of Co(NO 3 ) 2 ˙6H 2 O, 8mmol Ni(NO 3 ) 2 ˙6H 2 O, 20mmol hexamethylenetetramine, heating to 85°C, keeping the temperature for 6h; washing with water, centrifuging, and freeze-drying to obtain a composite material;

[0050] S3, placing 0.2 g of the composite material prepared in step S2 and 2 g of melamine in a tube furnace at N 2 The temperature was raised to 700 °C under atmosphere, and the temperature was kept for 2 h. The heating and cooling rates were both 2 °C / min. After cooling to room temperature, accordion-shaped Ti 3 C 2 T X MXene composites.

[0051] See also Figure 6 Figure (c) shows the Ti prepared in this example. 3 C 2 T X MXene composite materials have a minimum reflection loss of -10.9dB and an effective absorption bandwidth of 0.88GHz.

[0052] It can be seen from Figure 6 that the change of the minimum reflection loss curve shows that the Ti3C2Tx MXene composite exhibits excellent microwave absorption performance and a wide effective absorption bandwidth, and the electromagnetic microwave absorption performance related to interlayer nitrogen-doped carbon nanotubes; and it is shown that the electromagnetic wave absorption performance can be effectively regulated and optimized by the amount of melamine precursor to achieve full absorption in the Ku band.

[0053] It can be seen from Figure 2 that Figure 2 Figure (a) in 3 C 2 T X is the scanning electron microscopy image of the Ti Figure 2 C 3 C 2 T X MXene composite prepared in Example 1, Figure 2 Figure (b) in 3 C 2 T X is the scanning electron microscopy image of the Ti

[0054] It can be seen from Figure 3 that Figure 3 Figure (a) in 3 C 2 T X is the transmission electron microscopy image of the Ti Figure 3 C 3 C 2 T X MXene composite prepared in Example 1, Figure 3 Figure (b) in 3 C 2 T X is the transmission electron microscopy image of the Ti

[0055] It can be seen from Figure 4 that Figure 4 Figure (a) in 3 C 2 T X is the transmission electron microscopy image of the Ti Figure 4 C 3 C 2 T XMXene composite material Figure 4 In Figure (c), it is the schematic diagram of the interlayer spacing of the Ti 3 C 2 T X MXene composite material prepared in Example 3. It can be seen from the figure that the composite material forms nitrogen-doped carbon nanotube arrays NCNTs through melamine providing carbon and nitrogen sources and reduced layered cobalt-nickel hydroxide alloy as the catalytic source; the adjustable interlayer spacing of the Ti3C2Tx MXene composite material can be effectively controlled by controlling the amount of the melamine precursor.

[0056] Comparative Example 1:

[0057] A preparation method of a composite material includes the following steps:

[0058] S1. Add 1.6 g of lithium fluoride into a mixed solution containing 25 ml of 9 mol / L hydrochloric acid aqueous solution and 5 mL of hydrofluoric acid, then continue to add 1.2 g of Ti 3 AlC 2 , heat to 40 °C, keep warm and continuously stir for 24 h, wash repeatedly, centrifuge with deionized water for multiple times until the pH of the supernatant is 6 - 7, freeze-dry for 24 h to obtain a powder, and store it in vacuum;

[0059] Please refer to Figure 5 , which is the scanning electron microscope image of the composite material prepared in Comparative Example 1; please refer to Figure 7 , as Figure 7 shown in Figure (a) in 3 C 2 Tx MXene has a minimum reflection loss of -7.2 dB at a low filler content.

[0060] Comparative Example 2:

[0061] A preparation method of a composite material includes the following steps:

[0062] S1. Add 1.6 g of lithium fluoride into a mixed solution containing 25 ml of 9 mol / L hydrochloric acid aqueous solution and 5 mL of hydrofluoric acid, then continue to add 1.2 g of Ti 3 AlC 2 , heat to 40 °C, keep warm and continuously stir for 24 h, wash repeatedly, centrifuge with deionized water for multiple times until the pH of the supernatant is 6 - 7, freeze-dry for 24 h to obtain a powder, and store it in vacuum;

[0063] S2. Pyrolyze the powder prepared in step S1 under the protection of N 2 gas at 700 °C for 2 h, with a heating and cooling rate of 2 °C / min, and wait until the temperature cools down to room temperature to obtain the composite material.

[0064] Please refer to Figure 7 , as shown in Figure (b) of Figure 7 , the minimum reflection loss of the composite material prepared in Comparative Example 2 reaches -9.05 dB.

[0065] Performance detection

[0066] Paraffin was uniformly mixed with the composite materials (15 wt%) prepared in Examples 1-3 and Comparative Examples 1-2. After vacuum heating and melting, the mixed material 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 2.5 mm using a mold. The electromagnetic parameters of the coaxial ring sample were tested using a vector network analyzer (Ceyear 3656D). The electromagnetic microwave absorption performance was fitted with the minimum reflection loss (RL) at different thicknesses according to the transmission line theory formula:

[0067]

[0068]

[0069] In the formula, Z in is the effective input impedance, Z 0 is the free space impedance, ε r = ε'-jε″ and μ r = μ′-jμ″ represent the complex permittivity and complex permeability respectively, f is the frequency, d is the corresponding thickness, and c is the speed of light in vacuum. The detection results are shown in Table 1;

[0070] Table 1: Minimum reflection loss data of Examples 1-3 and Comparative Examples 1-2

[0071] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Minimum reflection loss -55.8dB -21.6dB -10.9dB -7.2dB -9.05dB

[0072] As can be seen from Table 1, the accordion-like Ti3C2Tx MXene composite material prepared in this application has excellent electromagnetic microwave absorption performance.

[0073] The above has described a specific embodiment of the present invention in detail, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. Preparation method of accordion-like Ti3C2Tx MXene composite material, characterized in that, it comprises the following steps: S1. Add Ti3AlC2 into the etching solution, carry out heat preservation reaction, centrifuge, wash with water, and freeze-dry to obtain powder; S2. Disperse the powder obtained in step S1 in a solution, add mixed transition metal ions and hexamethylenetetramine, carry out heat preservation reaction, wash with water, centrifuge, and freeze-dry to obtain the composite material; S3. Place the composite material and melamine obtained in step S2 in a reactor, under a nitrogen atmosphere, raise the temperature for reaction, and cool to room temperature to obtain an accordion-like Ti3C2TX MXene composite material with adjustable interlayer spacing; In step S2, the mixed transition metal ions are Co 2+ metal ions and Ni 2+ metal ions are mixed to obtain the Co 2+ metal ions, Ni 2+ The addition amounts of metal ions, hexamethylenetetramine, and the powder are 2 - 8 mmol: 4 - 16 mmol: 10 - 40 mmol: 100 - 300 mg.

2. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the water washing in S1 is specifically: wash with water until the pH of the upper layer liquid is 6-7; the freeze-drying is specifically: at -60 to -50 °C, dry for 20-30 h.

3. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the preparation method of the etching solution: (1) Mix 20-40 mL of 9-12 mol / L hydrochloric acid solution and 1-5 mL of hydrofluoric acid to obtain a mixed solution; (2) Mix the mixed solution obtained in step (1) with 1-2.4 g of lithium fluoride to obtain the etching solution.

4. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the heat preservation reaction in step S1 is specifically: the reaction temperature is 35-45 °C, and under heat preservation conditions, continuously stir for 24-48 h.

5. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the heat preservation reaction in step S2 is specifically: under water bath conditions, raise the temperature to 80-90 °C, and carry out heat preservation reaction for 4-8 h.

6. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the mass ratio of the composite material to melamine in step S3 is 1:1-10.

7. The preparation method of an accordion-like Ti3C2Tx MXene composite material according to claim 1, characterized in that, the heat preservation reaction in step S3 is specifically: raise the temperature to 650-750 °C, carry out heat preservation reaction for 1-3 h, and the heating rate and cooling rate are both 1-3 °C / min.

8. An accordion-like Ti3C2Tx MXene composite material, characterized in that, it is prepared by the preparation method described in any one of claims 1-7.

9. The application of an accordion-like Ti3C2Tx MXene composite material according to claim 8, characterized in that, it is applied in the field of electromagnetic microwave absorption.

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