A morphology-controllable Ti3C2T x MXene / Co / C composite materials, preparation methods and applications

Abstract

The invention discloses a morphology-controllable Ti3C2T x MXene / Co / C composite material, preparation method and application thereof, the present invention prepares Ti3C2T by hydrothermal carbonization method x MXene / Co / C absorbing material. Different amounts of NH3·H2O are added to the precursor mixed solution to adjust the pH of the solution, change the surface energy of different crystal faces, change the growth mode of the crystal to a certain extent, and calcine to synthesize single-substance Co magnetic nanomaterials of different dimensions. The present invention breaks the limitations of traditional preparation methods. In the prepared absorbing material, the dosage of NH3·H2O in the precursor mixed solution can adjust the reaction speed of the pH value of the reaction system, thereby changing the growth rate of different crystal faces, and finally synthesizing single-substance Co particles of different morphologies. Among them, the block structure, the cut-angle columnar structure, and the nanorod structure have a larger surface area, which increases the reflection and scattering of the incident electromagnetic wave, effectively prolongs the propagation path of the electromagnetic wave, and brings more interface charge polarization, thereby improving the loss performance of the electromagnetic wave.

Description

Technical Field

[0001] The present invention relates to a wave absorbing material, in particular to a Ti3C2T3 absorbing material with controllable morphology. x MXene / Co / C composite materials, preparation methods and applications. Background Art

[0002] In the information-based 21st century, the ever-changing electronic technology has made electromagnetic waves widely used in many fields and penetrated into every corner of human life. Whether it is electronic products such as mobile phones, microwave ovens, wireless communications in daily life, or national defense military equipment such as radars and missiles. The rapid development of electromagnetic applications has created huge material benefits, but it has also brought a series of serious problems, such as damaging human physical and mental health, causing disorders of the nervous system and immune system, and affecting the normal operation of precision electronic instruments, various wireless communications, aerospace and other equipment. Therefore, the increasingly serious electromagnetic wave pollution and interference has been called the "fourth largest public hazard in the world" in addition to air, water and noise pollution, so it is very necessary to prevent and control the interference of electromagnetic radiation for our physical health and living environment. In addition, in the military field, due to the increasingly fierce international competition in weapons and equipment, the stealth of military targets can be achieved by reducing electromagnetic radiation, thereby greatly improving the survivability and penetration capability of weapon systems. To this end, it is crucial to find suitable electromagnetic wave absorbing materials to protect against electromagnetic radiation.

[0003] Absorbing materials refer to a type of functional material that can convert the energy of electromagnetic waves projected onto its surface into heat energy or other forms of energy through dielectric loss.

[0004] MXene materials have become one of the most popular two-dimensional materials due to their rich elemental composition, unique two-dimensional structure, excellent electrical and optical properties, and thermodynamic properties. In addition, due to their large specific surface area, excellent hydrophilicity, and rich adjustable surface functional groups, two-dimensional MXene has been developed and applied in a variety of fields, such as ion batteries, supercapacitors, energy conversion and storage, sensors, and electromagnetic protection, especially in the fields of microwave absorption (MA) and electromagnetic interference (EMI). However, the microwave absorption performance of a single MXene is about -11.0dB to -14.4dB, so MXene alone is not good enough as a microwave absorption material. MXene materials are usually used in combination with other materials with different loss mechanisms to improve impedance matching.

[0005] Magnetic particles are typical electromagnetic wave magnetic loss materials due to their relatively high saturation magnetization. Magnetic particles mainly lose electromagnetic waves through hysteresis loss, domain wall resonance and magnetic aftereffect loss. Fe, Fe3O4, Ni, NiO, Co and CoO are all early and mature magnetic loss absorbing materials.

[0006] Whether it is MXene materials or magnetic particles, a single absorber has its own advantages and disadvantages. For example, MXene materials have a special layered structure and rich functional groups, but their electrical conductivity is too high, which makes electromagnetic waves easy to reflect, resulting in reduced impedance matching. Magnetic particles have the characteristics of strong electromagnetic wave absorption, but they have high density and poor stability. Using a specific method to compound layered MXene materials with magnetic particles can take into account both dielectric loss and magnetic loss, improve the impedance matching of materials, reduce reflection, and enhance electromagnetic wave absorption. The development of this excellent MXene / magnetic particle composite absorber that is "thin, light, wide, and strong" has important academic and application value.

[0007] Many researchers have been trying to find simple and practical methods to prepare absorbing materials, so as to further improve the functional properties of composite materials and make them useful as new materials such as microwave absorption. Generally speaking, experimental methods such as self-assembly, in-situ growth, hydrothermal and solvothermal methods are currently the most commonly used methods for preparing absorbing materials.

[0008] In order to break the limitation of the traditional preparation method, the present invention adopts a method combining hydrothermal and carbonization to prepare the composite material. The advantages of this method are safe and simple operation, and reduced pollution to the environment during the experiment. In addition, during the carbonization process, the generation of graphite carbon increases the dielectric loss of the composite material, thereby increasing its wave absorbing performance. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a Ti3C2T x

[0010] MXene / Co / C composite material, preparation method and application. The present invention first prepares a MXene layer structure with adjustable interlayer spacing to provide a favorable interface for the subsequent doping of metal particles, and then provides a method for synthesizing and controlling the morphology of magnetic metal Co, that is, by adjusting the pH value of the solution, different Co crystal planes are obtained, and single-substance Co magnetic nanomaterials of different dimensions are synthesized, and their wave absorption performance and wave absorption mechanism are studied.

[0011] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0012] A morphology-controllable Ti3C2T x A method for preparing a MXene / Co / C composite material, the method comprising the following steps:

[0013] Step (1): Dissolve Co(NO3)2·6H2O and 4,4'-biphenyldicarboxylic acid (H2BPDC) in a mixed solvent consisting of N,N-dimethylacetamide (DMAC) and ethanol (EtOH) in turn, stir evenly to obtain a pink solution, then add 10DA-Ti3C2, stir, and then add NH3·H2O solution to adjust the pH to 10.1-10.5, and the solution changes from pink to dark purple;

[0014] Step (2): transferring the solution obtained in step (1) to a reactor for hydrothermal reaction, washing the obtained product with a mixed solvent, and vacuum drying to obtain a precursor MXene / Co-MOF;

[0015] Step (3): The precursor MXene / Co-MOF obtained in step (2) is transferred to a tube furnace and carbonized at high temperature in an Ar atmosphere to obtain Ti3C2T x MXene / Co / C composites.

[0016] Furthermore, in the step (1), the molar ratio of Co(NO3)2·6H2O to H2BPDC is 1:1.

[0017] Furthermore, in the step (1), the mass ratio of Co(NO3)2·6H2O to 10DA-Ti3C2 is 2.2:1.

[0018] Furthermore, in the step (1), the volume ratio of DMAC to EtOH solution is 5:3.

[0019] Furthermore, in the step (1), the mass concentration of the NH3·H2O solution is 25 wt%, and the NH3·H2O solution is added to adjust the solution to pH=10.2-10.4.

[0020] Furthermore, in step (2), the hydrothermal reaction temperature is 150-170° C., preferably 150° C., and the reaction time is 3-4 h, preferably 3 h.

[0021] Further, the mixed solvent in step (2) is V DMAC :V EtOH =1:1 mixed solution, the vacuum drying temperature is 70-100°C, preferably 70°C, and the drying time is 22-25h, preferably 24h.

[0022] Furthermore, in step (3), the carbonization temperature is 550-600°C, preferably 600°C, the holding time is 2h, and the heating rate is 2°C·min -1 .

[0023] The present invention also provides Ti3C2T prepared by the preparation method xApplication of MXene / Co / C composites as microwave absorbing materials.

[0024] Ti3C2T prepared by the present invention x The minimum reflection loss value of MXene / Co / C composite material reaches -21.97dB, and the thickness of the absorption layer reaches 1.5mm.

[0025] Technical mechanism of the present invention: The present invention adjusts the interlayer spacing of Ti3C2Tx MXene by amino functionalization and welding of diacid molecules with different chain lengths. Subsequently, Ti3C2Tx MXene is prepared by hydrothermal-carbonization method. x MXene / Co / C composite materials, with the adjustment of the pH value of the solution, obtained different Co crystal planes and synthesized single-element Co magnetic nanomaterials of different dimensions.

[0026] The beneficial effects of the present invention are:

[0027] (1) Adjusting Ti3C2T by amino functionalization and welding diacid molecules with different chain lengths x The interlayer spacing of MXene is a key factor in the construction of metal / Ti3C2T x The MXene three-dimensional cross-linked network structure provides a favorable interface.

[0028] (2) Through the hydrothermal-carbonization method, different amounts of NH3·H2O were added to the solution to adjust the pH of the solution, change the surface energy of different crystal planes, and change the growth mode of the crystal to a certain extent, and finally synthesize single-substance Co magnetic nanomaterials with different morphologies. It should be pointed out that high-temperature carbonization can increase the graphitization degree of the composite material, thereby increasing the dielectric loss of the composite material to electromagnetic microwaves.

[0029] (3) The dosage of NH3·H2O in the precursor mixed solution can adjust the reaction speed of the pH value of the reaction system, thereby changing the growth rate and surface energy of different crystal planes, changing the growth mode of the crystal to a certain extent, and calcining to synthesize single-substance Co magnetic nanomaterials of different dimensions. Compared with nanoparticles, the bulk structure, the cut-angle column structure, and the nanorod structure have a larger surface area (pH = 10.2-10.4), increase the reflection and scattering of the incident electromagnetic wave, and bring more interface charge polarization, thereby significantly enhancing the absorption intensity of electromagnetic waves. In addition, the three-dimensional anisotropic structure formed by Co single substance and MXene increases the dielectric constant and dielectric loss, and increases the loss of electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a flow chart of a method for preparing an absorbing material according to an embodiment of the present invention;

[0032] Figure 2 The SEM images of the preparation methods of the absorbing materials of Examples 1 to 5 of the present invention, wherein a-Example 1, b-Example 2, c-Example 3, d-Example 4, e-Example 5;

[0033] Figure 3 XRD diagrams of the absorbing materials of Example xDA-Ti3C2 and Examples 1-5 of the present invention;

[0034] Figure 4 These are graphs showing the wave absorbing performance of the wave absorbing materials of Examples 1 to 5 of the present invention, wherein a is Example 1, b is Example 2, c is Example 3, d is Example 4, and e is Example 5. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and those skilled in the art in this field can make some non-essential improvements and adjustments based on the content of the above invention.

[0036] The preparation method of 10DA-Ti3C2 in the present invention is as follows:

[0037] Step 1: 1.6 g lithium fluoride was slowly dissolved in 9 M hydrochloric acid and stirred for 10 minutes to fully dissolve;

[0038] Step 2: Slowly add 1.0g Ti3AlC2 and stir at 40-50℃ for 48 hours;

[0039] Step 3: Wash twice with dilute hydrochloric acid (1M) to remove excess lithium fluoride;

[0040] Step 4: Wash with deionized water and centrifuge at a speed of 3500 rpm for 5 minutes each time, 6-8 times, until the pH of the solution is greater than 6;

[0041] Step 5: Collect the precipitate, dissolve it in 100 mL of water, and ultrasonicate it for 2 hours under an argon atmosphere. Finally, centrifuge it at 3500 r / min for 30 minutes, collect the supernatant, and obtain the Ti3C2 solution for later use;

[0042] Step 6: Disperse 20 mL of Ti3C2 solution (5 mg / mL) into 60 mL of NH4F solution (111 mg / mL), stir at 60 °C for 24 h (N2 atmosphere), wash with deionized water several times and freeze-dry to obtain Ti3C2-NH2;

[0043] Step 7: Take 100 mg of Ti3C2-NH2 and 50 mL of ethanol solution of dodecanedioic acid (1 mg / mL), mix and stir for 4 hours, wash with deionized water to pH = 7, and then freeze-dry the mixture overnight to obtain 10DA-Ti3C2.

[0044] Example 1

[0045] like Figure 1 As shown, the morphology of the Ti3C2T x The preparation method of MXene / Co / C composite material comprises the following steps:

[0046] Step (1): 0.3 mmol of Co(NO3)2·6H2O (0.0873 g) and 0.3 mmol of H2BPDC were dissolved in a mixed solvent containing 10 mL of DMAC and 6 mL of EtOH, and the mixture was stirred at 400 r·min. -1 The mixture was stirred for 40 min to obtain a uniform pink solution, and then 0.04 g of 10DA-Ti3C2 was added and the mixture was stirred at 400 r·min. -1 Stir for 30 min, add 25 wt% NH3·H2O solution, adjust the solution to pH = 10.1, and the solution changes from pink to dark purple;

[0047] Step (2): The solution obtained in step (1) was transferred to a 100 mL reactor and reacted in an oven at 150° C. for 3 h. The obtained product was precipitated with a mixed solvent (V DMAC :V EtOH =1:1) washed three times, and dried in a 70°C oven under vacuum for 24 h to obtain the precursor MXene / Co-MOF;

[0048] Step (3): The precursor MXene / Co-MOF obtained in step (2) was transferred to a tube furnace and heated at 2 °C min in an Ar atmosphere. -1 The temperature was raised to 600 °C and kept for 2 h to obtain the product Ti3C2T x MXene / Co / C, named MX / Co / C-1.

[0049] Example 2

[0050] The difference from Example 1 is that in step (1), 25 wt % NH 3 · H 2 O solution is added to adjust the pH to 10.2. The other steps are the same as Example 1, and the product is named MX / Co / C-2.

[0051] Example 3

[0052] The difference from Example 1 is that in step (1), 25 wt % NH 3 · H 2 O solution is added to adjust the pH to 10.3. The other steps are the same as Example 1, and the product is named MX / Co / C-3.

[0053] Example 4

[0054] The difference from Example 1 is that in step (1), 25 wt % NH 3 · H 2 O solution is added to adjust the pH to 10.4. The other steps are the same as Example 1, and the product is named MX / Co / C-4.

[0055] Example 5

[0056] The difference from Example 1 is that in step (1), 25 wt % NH 3 · H 2 O solution is added to adjust the pH to 10.5. The other steps are the same as Example 1, and the product is named MX / Co / C-5.

[0057] Example 6

[0058] The morphology of the Ti3C2T x The preparation method of MXene / Co / C composite material comprises the following steps:

[0059] Step (1): 0.3 mmol of Co(NO3)2·6H2O and 0.3 mmol of H2BPDC were dissolved in a mixed solvent containing 10 mL of DMAC and 6 mL of EtOH, and the mixture was stirred at 400 r·min. -1 The mixture was stirred for 40 min to obtain a uniform pink solution, and then 0.04 g of 10DA-Ti3C2 was added and the mixture was stirred at 400 r·min. -1 Stir for 30 min, add 25 wt% NH3·H2O solution, adjust the solution to pH = 10.2, and the solution changes from pink to dark purple;

[0060] Step (2): The solution obtained in step (1) was transferred to a 100 mL reactor and reacted in an oven at 160° C. for 3 h. The obtained product was precipitated with a mixed solvent (V DMAC :V EtOH =1:1) washed three times, and dried in an oven at 80°C under vacuum for 22 h to obtain the precursor MXene / Co-MOF;

[0061] Step (3): The precursor MXene / Co-MOF obtained in step (2) was transferred to a tube furnace and heated at 2 °C min in an Ar atmosphere. -1 The temperature was raised to 550°C and kept at this temperature for 2 h to obtain the product.

[0062] Example 7

[0063] The morphology of the Ti3C2T x The preparation method of MXene / Co / C composite material comprises the following steps:

[0064] Step (1): 0.3 mmol of Co(NO3)2·6H2O and 0.3 mmol of H2BPDC were dissolved in a mixed solvent containing 10 mL of DMAC and 6 mL of EtOH, and the mixture was stirred at 400 r·min. -1 The mixture was stirred for 40 min to obtain a uniform pink solution, and then 0.04 g of 10DA-Ti3C2 was added and the mixture was stirred at 400 r·min. -1 Stir for 30 min, add 25 wt% NH3·H2O solution, adjust the solution to pH = 10.3, and the solution changes from pink to dark purple;

[0065] Step (2): The solution obtained in step (1) was transferred to a 100 mL reactor and reacted in an oven at 170° C. for 4 h. The obtained product was precipitated with a mixed solvent (V DMAC :V EtOH =1:1) washed three times, and dried in a 90°C oven under vacuum for 20 h to obtain the precursor MXene / Co-MOF;

[0066] Step (3): The precursor MXene / Co-MOF obtained in step (2) was transferred to a tube furnace and heated at 2 °C min in an Ar atmosphere. -1 The temperature was raised to 620°C and kept at this temperature for 2 h to obtain the product.

[0067] Example 8

[0068] The morphology of the Ti3C2T x The preparation method of MXene / Co / C composite material comprises the following steps:

[0069] Step (1): 0.3 mmol of Co(NO3)2·6H2O and 0.3 mmol of H2BPDC were dissolved in a mixed solvent containing 10 mL of DMAC and 6 mL of EtOH, and the mixture was stirred at 400 r·min. -1 The mixture was stirred for 40 min to obtain a uniform pink solution, and then 0.04 g of 10DA-Ti3C2 was added and the mixture was stirred at 400 r·min. -1Stir for 30 min, add 25 wt% NH3·H2O solution, adjust the solution to pH = 10.4, and the solution changes from pink to dark purple;

[0070] Step (2): The solution obtained in step (1) was transferred to a 100 mL reactor and reacted in an oven at 150° C. for 3 h. The obtained product was precipitated with a mixed solvent (V DMAC :V EtOH =1:1) washed three times, and dried in an oven at 80°C under vacuum for 22 h to obtain the precursor MXene / Co-MOF;

[0071] Step (3): The precursor MXene / Co-MOF obtained in step (2) was transferred to a tube furnace and heated at 2 °C min in an Ar atmosphere. -1 The temperature was raised to 650°C and kept at this temperature for 2 h to obtain the product.

[0072] 1. Scanning electron microscopy analysis

[0073] The Ti3C2T prepared in Examples 1-5 x The MXene / Co / C absorbing material was tested by scanning electron microscopy. The results are as follows Figure 2 As shown in (ae), when pH = 10.1, Co nanoparticles are distributed in Ti3C2T x MXene surface and layers; carbonized Ti3C2T x MXene still retains a relatively complete accordion structure. When pH = 10.2, the morphology of single-element Co is irregular block particles. When pH = 10.3, the morphology of single-element Co is a regular corner-cut column structure embedded in Ti3C2T x When pH = 10.4, the single Co nanorods have uniform length and grow on Ti3C2T x When pH = 10.5, the number of Co nanoparticles increases, mostly distributed on the Ti3C2T x MXene surface.

[0074] Ti3C2T x XRD patterns of MXene / Co / C absorbers are shown in the attached figure. Figure 3 shown.

[0075] from Figure 3It can be seen that for MX / Co / C-1 and MX / Co / C-3, the characteristic peaks at 44.2°, 51.5° and 75.8° correspond to the (111), (200) and (220) crystal planes of face-centered cubic Co, respectively (PDF#15-0806). For MX / Co / C-2 and MX / Co / C-4, the characteristic peaks at 44.2°, 51.5° and 75.8° correspond to the (111), (200) and (220) crystal planes of face-centered cubic Co, respectively (PDF#89-7093). For MX / Co / C-5, the characteristic peaks at 44.2°, 51.5° and 75.8° correspond to the (111), (200) and (220) crystal planes of face-centered cubic Co, respectively (PDF#01-1255). Combined with SEM images, at pH = 10.1, the strength of the three crystal planes of MX / Co / C-1 is relatively weak, and the Co element is granular. At pH = 10.2, the strength of the three crystal planes of MX / Co / C-2 increases significantly, and the Co element is irregular blocks. This shows that with the increase in the amount of NH3·H2O added, the pH value of the mixed solution increases, thereby accelerating the nucleation and growth of crystals. At pH = 10.3, the strength of the three crystal planes of MX / Co / C-3 is significantly weakened, and the Co element is a regular cut-angle columnar structure. At pH = 10.4, the three crystal planes of MX / Co / C-4 have the highest strength, and the Co element is a nanorod with uniform length. At pH = 10.5, the strength of the three crystal planes of MX / Co / C-5 decreases, and the number of Co nanoparticles on the surface of the composite material increases.

[0076] 2. Wave absorbing performance test analysis

[0077] The present invention firstly mixes paraffin (43%) and sample (57%) uniformly and then presses them into concentric ring samples with an inner diameter of 3.04 mm and an outer diameter of 7.00 mm. Then the electromagnetic parameters of the samples are tested in the frequency range of 2.0-18.0 GHz by using the N5244A vector network analyzer (VNA) of Agilent Technologies, USA.

[0078] The reflection loss of the material within the measurement frequency range is calculated by combining the electromagnetic parameters with the thickness of the material, thereby evaluating the material's absorbing performance.

[0079] Generally speaking, we define effective absorption as an absorption rate greater than 90%, or an equivalent reflection loss of -10dB.

[0080] The prepared Ti3C2T x The MXene / Co / C absorbing material was tested for its absorbing performance. The results are as follows: Figure 4As shown. It can be seen from the figure that for MX / Co / C-1, the minimum reflection loss value is -17.46dB, and the thickness of the absorption layer is 5.0mm. For MX / Co / C-2, the minimum reflection loss value is -21.97dB, and the thickness of the absorption layer is 5.0mm, which has the best magnetic wave loss capacity among all samples. For MX / Co / C-3, the minimum reflection loss value is -17.19dB, and the thickness of the absorption layer is 2.5mm. For MX / Co / C-4, the minimum reflection loss value is -17.70dB, and the thickness of the absorption layer is 1.5mm, which has the smallest matching thickness among all samples. For MX / Co / C-5, the minimum reflection loss values ​​are all above -10dB, indicating that its electromagnetic wave loss capacity is very poor. The high conductivity caused by the generation of more metal Co will lead to the skin effect, increase the reflection of the incident electromagnetic wave on the surface of the material, and thus reduce the wave absorption performance of the composite material. This may be the reason why the wave absorption performance of MX / Co / C-5 is not ideal.

[0081] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A morphology-controlled Ti3C2T x The method for preparing a MXene / Co / C composite material is characterized in that: The following steps are involved: Step (1): Dissolve Co(NO3)2·6H2O and 4,4'-biphenyldicarboxylic acid (H2BPDC) in a mixed solvent consisting of N,N-dimethylacetamide (DMAC) and ethanol (EtOH) in turn, stir evenly to obtain a pink solution, then add 10DA-Ti3C2, stir, and then add NH3·H2O solution to adjust the pH to 10.1-10.5, and the solution changes from pink to dark purple; Step (2): transferring the solution obtained in step (1) to a reactor for hydrothermal reaction, washing the obtained product with a mixed solvent, and vacuum drying to obtain a precursor MXene / Co-MOF; Step (3): The precursor MXene / Co-MOF obtained in step (2) is transferred to a tube furnace and carbonized at high temperature in an Ar atmosphere to obtain Ti3C2T x MXene / Co / C composites.

2. Ti3C2T according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: In the step (1), the molar ratio of Co(NO3)2·6H2O to H2BPDC is 1:

1.

3. Ti3C2T according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: In the step (1), the mass ratio of Co(NO3)2·6H2O to 10DA-Ti3C2 is 2.2:

1.

4. Ti3C2T according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: The volume ratio of DMAC and EtOH in the step (1) is 5:

3.

5. The Ti3C2T3 according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: The mass concentration of the NH3·H2O solution in step (1) is 25wt%, and the NH3·H2O solution is added to adjust the solution to pH=10.2-10.

4.

6. Ti3C2T according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: The hydrothermal reaction temperature in step (2) is 150-170° C., and the reaction time is 3-4 hours.

7. The Ti3C2T3 according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: The mixed solvent in step (2) is V DMAC :V EtOH =1:1 mixed solution, vacuum drying temperature is 70-100℃, drying time is 22-25h.

8. The Ti3C2T3 according to claim 1 x The preparation method of MXene / Co / C composite material is characterized by: In step (3), the carbonization temperature is 550-600°C, the holding time is 2h, and the heating rate is 2°C·min -1 .

9. Ti3C2T prepared by the preparation method according to any one of claims 1 to 8 x Application of MXene / Co / C composites as microwave absorbing materials.

10. The use according to claim 9, characterized in that: Ti3C2T x The minimum reflection loss value of MXene / Co / C composite material reaches -21.97dB, and the thickness of the absorption layer reaches 1.5mm.

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