Bimetal MXene TiVCTx / Fe3O4 composite material as well as preparation method and application thereof

Abstract

The invention discloses a bimetallic MXene TiVCTx / Fe3O4 composite material as well as a preparation method and application thereof, and belongs to the field of electromagnetic wave absorbing materials. The invention aims to solve the problem that the existing MXene cannot meet the requirements of thin thickness, wide bandwidth and low reflection loss of a new electromagnetic wave absorber. The diameter of Fe3O4 is 30nm, the Fe3O4 is stably loaded on a TiVCTx nanosheet, a TiVCTx crystal structure is a hexagonal crystal system structure (space group P63 / mmc), and the sheet diameter of the TiVCTx nanosheet is 5 + / -2 [mu] m. Compared with common Ti3C2Tx, the introduction of V causes lattice distortion and forms a defect which can be used as a polarization center in MXene, changes the distribution of charges around metal atoms, forms a local electric field, generates a large number of dipoles, and greatly enhances the polarization loss of the material. The fabric has good electromagnetic wave absorption performance.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorbing materials, and in particular relates to a bimetallic MXene TiVCT x / Fe3O4 composite material and its preparation method and application. Background Art

[0002] With the advent of the intelligent era, wireless communications and detection technologies based on electromagnetic field theory are experiencing continuous breakthroughs and innovations, providing technical support for cutting-edge fields such as aerospace and satellite GPS. However, large amounts of electromagnetic pollution can have adverse effects on the human body, the environment, and equipment, and electromagnetic wave absorbing materials have become a major approach to combating this pollution.

[0003] MXene is a new type of two-dimensional transition metal carbide / nitride material with a layered structure. Due to its two-dimensional layered structure and rich functional group sites, it is believed to have broad prospects in the field of electromagnetic wave absorption and has become an important research object for solving the current electromagnetic pollution problem. For example, Chinese patent CN202311177914.0 prepared a ZnO@Fe / Ti3C2T x MXene absorbing coating has good electromagnetic wave absorption performance; Chinese patent CN202411271678.3 prepared an Archimedean screw-shaped Ti3C2T by freeze-drying method x MXene aerogel has intrinsic magnetism and enhances electromagnetic wave absorption performance. However, most current research focuses on Ti3C2T x MXene, but neglected the research on MXene in other systems.

[0004] In addition, due to the single reflection loss and the impedance mismatch caused by the excessively high complex dielectric constant and the excessively low complex magnetic permeability, MXene cannot meet the requirements of thin thickness, wide bandwidth and low reflection loss for new electromagnetic wave absorbers.

[0005] In summary, preparing new MXene and introducing multiple loss mechanisms by compounding other materials to achieve good electromagnetic wave absorption performance has become an urgent problem to be solved in the field of electromagnetic wave absorption of MXene. Summary of the Invention

[0006] The present invention aims to solve the problem that MXene cannot meet the requirements of thin thickness, wide bandwidth and low reflection loss of new electromagnetic wave absorbers due to single reflection loss and impedance mismatch caused by too high complex dielectric constant and too low complex magnetic permeability.

[0007] In order to avoid the repetitiveness of MXene material research and make MXene materials meet the requirements of new electromagnetic wave absorbers, the present invention provides a bimetallic MXene TiVCT x / Fe3O4 composite material and preparation method thereof, the present invention synthesizes a bimetallic MXene TiVCT by means of solid phase sintering method, fluoride salt acid etching method and electrostatic self-assembly strategy x This electromagnetic absorber exhibits a synergistic effect of multiple loss mechanisms, including V and Fe₃O₄. The solid solution of V and the composite of Fe₃O₄ introduce strong polarization and magnetic losses, effectively optimizing impedance matching. Thanks to the synergistic effects of conductivity, polarization, and magnetic losses, the composite material exhibits excellent electromagnetic absorption performance.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions: The purpose of the present invention is to provide a bimetallic MXene TiVCT x The preparation method of the composite material comprises the following steps: Step 1: titanium, vanadium, aluminum and carbon are mixed in a mass ratio of 1:1:1.1:0.8, anhydrous ethanol is added, and the mixture is ball-milled, dried, pressed into tablets, gradient sintered, polished until the surface color is uniform, crushed and sieved to obtain TiVAlC powder; Step 2: Mix the HCl solution and LiF, heat in an oil bath under magnetic stirring until the LiF is completely dissolved, slowly add TiVAlC powder in small amounts and multiple times until it is completely dissolved and mixed, and then stir; Step 3: First, pickle and then centrifuge with deionized water until the pH value is 5-6, and then dry to obtain TiVCT. x ; Step 4: Combine positively charged Fe3O4 nanoparticles and TiVCT x , poured into deionized water and dispersed evenly, ultrasonicated for a period of time to obtain bimetallic MXene TiVCT x / Fe3O4 composite materials.

[0009] It is further defined that the ball milling is performed in a planetary ball mill at a rotation speed of 400 r / min for 10 hours.

[0010] It is further defined that the gradient sintering steps are as follows: loading into a graphite crucible, placing in a tubular furnace, heating from room temperature to 1000°C at a heating rate of 5°C / min, then heating to 1400°C after 140 minutes, heating to 1550°C after 75 minutes, and keeping warm for 2 hours, and finally cooling to room temperature.

[0011] Further defined, through a 400 mesh sieve.

[0012] It is further defined that the tablet is pressed at 5 MPa.

[0013] It is further defined that the usage ratio of TiVAlC powder, HCl and LiF is 1 g:20 mL:1.6 g, and the concentration of HCl solution is 12 M.

[0014] It is further defined that the positively charged modified Fe3O4 nanoparticles are prepared according to the following steps: poly (diallyldimethylammonium chloride) solution (20 wt%) is diluted with deionized water, Fe3O4 nanoparticles are added, ultrasonicated, washed by centrifugation with deionized water, and dried to obtain the positively charged modified Fe3O4 nanoparticles.

[0015] It is further defined that 100 mg of positively charged Fe3O4 nanoparticles and 100 mg of TiVCT x , poured into 50mL deionized water; ultrasonic time was 30min; step 4 ultrasonication allowed the two materials to fully contact, and the positively charged Fe3O4 was loaded onto the negatively charged TiVCT by electrostatic adsorption. x On nanosheets.

[0016] Another object of the present invention is to provide a bimetallic MXene TiVCT prepared by any of the above methods. x / Fe3O4 composite materials.

[0017] Further defined, TiVCT x The crystal structure is hexagonal (space group P63 / mmc), TiVCT x The nanosheets have a diameter of 5 ± 2 μm, the Fe3O4 diameter is 30 nm and is stably loaded on TiVCT. x On nanosheets.

[0018] Another object of the present invention is to provide a bimetallic MXene TiVCT prepared by any of the above methods. x / Fe3O4 composite materials are used as electromagnetic absorbing materials.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention synthesizes a bimetallic MXene TiVCT x / Fe3O4 composite electromagnetic absorbing material, compared with ordinary Ti3C2T xIn contrast, the introduction of V causes lattice distortion, creating defects in the MXene that can serve as polarization centers. This also alters the charge distribution around the metal atoms, forming local electric fields and generating a large number of dipoles, significantly increasing the material's polarization losses. The addition of Fe₃O₄ not only introduces magnetic losses but also effectively optimizes impedance matching. The synergistic effect of these multiple loss mechanisms results in the composite material exhibiting excellent electromagnetic wave absorption properties.

[0020] The present invention synthesizes a new bimetallic MXene TiVCT x Because of the multiple functional groups on its surface, it has good hydrophilicity and dispersibility.

[0021] The preparation process of the present invention is simple to operate, has low equipment requirements, is low in cost, and has a high safety factor of production raw materials.

[0022] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 TiVAlC and TiVCT in Example 1 of the present invention x and TiVCT x X-ray diffraction (XRD) patterns of / Fe3O4 composite materials; Figure 2 TiVAlC and TiVCT in Example 1 of the present invention x and TiVCT x Scanning electron microscope image (SEM) of / Fe3O4 composite material; Figure 3 Graphs showing the electromagnetic wave absorption performance and impedance matching of the composite material in Example 1 of the present invention; Figure 4 TiVCT in Example 2 of the present invention x X-ray diffraction (XRD) patterns of / Fe3O4 composite materials; Figure 5 TiVCT in Example 2 of the present invention x Scanning electron microscope image (SEM) of / Fe3O4 composite material; Figure 6 TiVCT in Example 2 of the present invention x Electromagnetic wave absorption performance diagram and impedance matching diagram of / Fe3O4 composite material. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention and are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make several variations and improvements without departing from the concept of the present invention.

[0025] Example 1 First, titanium: vanadium: aluminum: carbon (mass ratio = 1:1:1.1:0.8) was mixed. Anhydrous ethanol was added as a dispersant (the volume ratio of the total mass of titanium, vanadium, aluminum, and carbon to the dispersant was 1:4). The mixture was ball-milled in a planetary ball mill at 400 rpm for 10 hours. After ball-milling, the mixture was dried in an 80°C oven for 8 hours to obtain a uniformly mixed powder.

[0026] 2. Weigh 2 g of the ball-milled mixed powder, pour it into a tableting mold, and press it into a 13 mm diameter tablet at a pressure of 5 MPa.

[0027] 3. The above-mentioned disc was placed in a graphite crucible, placed in a tube furnace, and heated from room temperature to 1000°C at a heating rate of 5°C / min, then heated to 1400°C after 140 minutes, and then heated to 1550°C after 75 minutes, and kept at this temperature for 2 hours. Finally, the temperature was cooled to room temperature at the same rate (5°C / min) to obtain the precursor TiVAlC MAX phase.

[0028] Fourth, the obtained TiVAlC MAX phase was polished with sandpaper to remove surface impurities until the surface color was uniform, and then crushed in an agate mortar and sieved using a 400-mesh screen to obtain a MAX phase with a sufficiently small particle size.

[0029] 5. Separately weigh 1 g of TiVAlC powder, 20 mL of 12 M HCl, and 1.6 g of LiF. Pour the HCl and LiF into a 100 mL Teflon beaker and stir using a magnetic stirrer at 340 r / min for 20 minutes until the LiF is completely dissolved. Slowly add the TiVAlC in five portions until completely dissolved and mixed. Then, heat in a 50°C oil bath and stir at 340 r / min for 48 hours.

[0030] 6. After etching, use 2M HCl to etch the TiVCT x The MXene phase was acid-washed to remove excess LiF, and then centrifuged and washed with deionized water until the pH value was about 6. TiVCT was obtained by drying in a vacuum oven at 45 °C. x .

[0031] Seven, 20 mL of poly diallyl dimethyl ammonium chloride solution (20 wt%) was weighed, diluted to 50 mL with deionized water, and 500 mg of Fe3O4 nanoparticles were added to the diluted solution. The Fe3O4 nanoparticles were positively charged by ultrasonic treatment at a power of 400 W for 1 h. After completing the positive charge modification, the excess poly diallyl dimethyl ammonium chloride solution was removed by centrifugal washing 3-5 times with deionized water, and the positively charged Fe3O4 nanoparticles were obtained by drying.

[0032] Eight, 100 mg of positively charged Fe3O4 nanoparticles and 100 mg of TiVCT x were weighed respectively, poured into 50 mL of deionized water, and dispersed uniformly. The two materials were allowed to fully contact by ultrasonic treatment for 30 min, and the positively charged Fe3O4 was loaded onto the negatively charged TiVCT x nanosheets by electrostatic adsorption.

[0033] The X-ray diffraction (XRD) patterns of TiVAlC, TiVCT x and TiVCT x / Fe3O4 composites in this example are shown in Figure 1 , and it can be seen from Figure 1 that the XRD pattern of TiVAlC is in good agreement with the standard PDF card of 211 type MAX phase. In addition, the diffraction peak of aluminum at 40° disappears and the diffraction peak of the initial (002) plane moves from 12.9° to 9.1°. Finally, the XRD pattern of TiVCT x / Fe3O4 (mass ratio 1:1) shows Fe3O4 characteristic peaks compared with pure TiVCT x MXene. This indicates that TiVAlC, TiVCT x and TiVCT x / Fe3O4 are all successfully prepared. The scanning electron microscope images (SEM) of TiVAlC, TiVCT x and TiVCT x / Fe3O4 composites in this example are shown in Figure 2 , and it can be seen from Figure 2 (a) that TiVAlC shows a stable nanolayer structure, while Figure 2 (b) shows that TiVCT x has obvious delamination. As shown in Figure 2 (c), Fe3O4 nanoparticles are uniformly distributed on the TiVCT x nanosheets.

[0034] The electromagnetic wave absorption performance and impedance matching diagrams of the composites in this example are shown in Figure 3 , and it can be seen from Figure 3(a) It can be seen that TiVCT x When the mass ratio of Fe3O4 is 1:1, the minimum reflection loss is -43.594 dB, the effective absorption bandwidth reaches 4.56 GHz, and the electromagnetic wave absorption performance is excellent. Figure 3 (b) It can be seen that TiVCT x When the mass ratio of Fe3O4 to Fe3O4 is 1:1, the impedance matching characteristic is good, which explains why the present invention has good electromagnetic wave absorption performance.

[0035] Example 2 First, titanium: vanadium: aluminum: carbon (mass ratio = 1:1:1.1:0.8) was mixed. Anhydrous ethanol was added as a dispersant (the volume ratio of the total mass of titanium, vanadium, aluminum, and carbon to the dispersant was 1:4). The mixture was ball-milled in a planetary ball mill at 400 rpm for 10 hours. After ball-milling, the mixture was dried in an 80°C oven for 8 hours to obtain a uniformly mixed powder.

[0036] 2. Weigh 2 g of the ball-milled mixed powder, pour it into a tableting mold, and press it into a 13 mm diameter tablet at a pressure of 5 MPa.

[0037] 3. The above-mentioned disc was placed in a graphite crucible, placed in a tube furnace, and heated from room temperature to 1000°C at a heating rate of 5°C / min, then heated to 1400°C after 140 minutes, and then heated to 1550°C after 75 minutes, and kept at this temperature for 2 hours. Finally, the temperature was cooled to room temperature at the same rate (5°C / min) to obtain the precursor TiVAlC MAX phase.

[0038] Fourth, the obtained TiVAlC MAX phase was polished with sandpaper to remove surface impurities until the surface color was uniform, and then crushed in an agate mortar and sieved using a 400-mesh screen to obtain a MAX phase with a sufficiently small particle size.

[0039] 5. Separately weigh 1 g of TiVAlC powder, 20 mL of 12 M HCl, and 1.6 g of LiF. Pour the HCl and LiF into a 100 mL Teflon beaker and stir using a magnetic stirrer at 340 r / min for 20 minutes until the LiF is completely dissolved. Slowly add the TiVAlC in six portions until completely dissolved. Then, heat in a 50°C oil bath and stir at 340 r / min for 48 hours.

[0040] 6. After etching, use 2M HCl to etch the TiVCT x The MXene phase was acid-washed to remove excess LiF, and then centrifuged and washed with deionized water until the pH value was about 6. TiVCT was obtained by drying in a vacuum oven at 45 °C. x .

[0041] 7. Weigh 20 mL of a 20 wt% polydimethylammonium chloride solution and dilute it to 50 mL with deionized water. Add 500 mg of Fe₃O₄ nanoparticles to the diluted solution and sonicate at 400 W for 1 h to positively charge the Fe₃O₄ nanoparticles. After positive modification, wash the particles 3–5 times with deionized water to remove excess polydimethylammonium chloride solution and dry them to obtain the positively charged Fe₃O₄ nanoparticles.

[0042] 8. Weigh 200 mg of positively charged Fe3O4 nanoparticles and 100 mg of TiVCT x , poured into 50 mL of deionized water and dispersed evenly, ultrasonicated for 30 min to allow the two materials to fully contact, and the positively charged Fe3O4 was loaded onto the negatively charged TiVCT by electrostatic adsorption. x On nanosheets.

[0043] In this embodiment, TiVCT x The X-ray diffraction (XRD) patterns of the / Fe3O4 composite materials are shown in Figure 2. Figure 4 As shown by Figure 4 It can be seen that TiVCT x / Fe3O4 (mass ratio 1:2) compared with pure TiVCT x MXene has a characteristic peak of Fe3O4, and compared with the case of a mass ratio of 1:1 in Example 1, the characteristic peak of Fe3O4 is higher, which is consistent with the implementation situation.

[0044] In this embodiment, TiVCT x Scanning electron microscope (SEM) images of the / Fe3O4 composite material are shown in Figure 2. Figure 5 As shown by Figure 5 It can be seen that Fe3O4 nanoparticles are evenly distributed in TiVCT x On the nanosheets, there are obviously more Fe3O4 nanoparticles than in Example 1.

[0045] In this embodiment, TiVCT x The electromagnetic wave absorption performance and impedance matching diagram of the / Fe3O4 composite material are shown in Figure 6 As shown by Figure 6 (a) It can be seen that TiVCT x When the mass ratio of Fe3O4 is 1:2, the minimum reflection loss is -42.175 dB, the effective absorption bandwidth reaches 3.68 GHz, and the electromagnetic wave absorption performance is excellent. Figure 3 (b) It can be seen that TiVCT x When the mass ratio of Fe3O4 to Fe3O4 is 1:2, the impedance matching characteristic is good, which explains why the present invention has good electromagnetic wave absorption performance.

[0046] The specific embodiments of the present application are described above. It should be noted that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which do not affect the essence of the present application.

Claims

1. A bimetallic MXene TiVCT x The preparation method of / Fe3O4 composite material is characterized in that: The following steps are involved: Step 1: titanium, vanadium, aluminum and carbon are mixed in a mass ratio of 1:1:1.1:0.8, anhydrous ethanol is added, and the mixture is ball-milled, dried, pressed into tablets, gradient sintered, polished until the surface color is uniform, crushed and sieved to obtain TiVAlC powder; Step 2: Mix the HCl solution and LiF, heat in an oil bath under magnetic stirring until the LiF is completely dissolved, slowly add TiVAlC powder in small amounts and multiple times until it is completely dissolved and mixed, and then stir; Step 3: First, pickle and then centrifuge with deionized water until the pH value is 5-6, and then dry to obtain TiVCT. x ; Step 4: Combine positively charged Fe3O4 nanoparticles and TiVCT x , poured into deionized water and dispersed evenly, ultrasonicated for a period of time to obtain bimetallic MXene TiVCT x / Fe3O4 composite materials.

2. The method according to claim 1, characterized in that Ball milling was carried out in a planetary ball mill at a speed of 400 r / min for 10 h.

3. The method according to claim 1, characterized in that The gradient sintering steps are as follows: put into a graphite crucible, put into a tube furnace, heat from room temperature to 1000°C at a heating rate of 5°C / min, then heat to 1400°C after 140 minutes, heat to 1550°C after 75 minutes, keep warm for 2 hours, and finally cool to room temperature.

4. The method according to claim 1, characterized in that Pass through 400 mesh sieve.

5. The method according to claim 1, characterized in that: Press the tablet at 5MPa.

6. The method according to claim 1, characterized in that The dosage ratio of TiVAlC powder, HCl and LiF is 1 g:20 mL:1.6 g, and the concentration of HCl solution is 12 M.

7. The method according to claim 1, characterized in that Positively charged Fe3O4 nanoparticles were prepared according to the following steps: polydiallyldimethylammonium chloride solution (20 wt%) was diluted with deionized water, Fe3O4 nanoparticles were added, ultrasonicated, washed by centrifugation with deionized water, and dried to obtain positively charged Fe3O4 nanoparticles.

8. A bimetallic MXene TiVCT prepared by the method according to any one of claims 1 to 7 x / Fe3O4 composite materials.

9. The composite material according to claim 8, characterized in that: TiVCT x The crystal structure is hexagonal (space group P63 / mmc), TiVCT x The nanosheets have a diameter of 5 ± 2 μm, the Fe3O4 diameter is 30 nm and is stably loaded on TiVCT. x On nanosheets.

10. Bimetallic MXene TiVCT prepared by the method according to any one of claims 1 to 8 x / Fe3O4 composite materials are used as electromagnetic absorbing materials.

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