Composite wave-absorbing material prepared by MXene / hetero-metal MOFs derivation and method thereof

Abstract

The application discloses a kind of MXene / heterogeneous metal MOFs derived preparation composite wave-absorbing materials and method thereof.It is with MXene as base, MXene is mixed with heterogeneous metal salt, organic ligand and surfactant reaction, in-situ generation MXene / heterogeneous metal MOFs composite, then the composite is annealed by high temperature, make MXene in the composite be converted into amorphous carbon, and TiO2 is precipitated on the surface, while heterogeneous metal MOFs is converted into graphite carbon and heterogeneous alloy nanoparticles, obtain a new type of heterogeneous metal MOFs derived carbon-based nanocomposite wave-absorbing material.The composite wave-absorbing material prepared by the application has good impedance matching and excellent microwave absorption performance under thinner thickness and lighter mass, and has potential application value in the field of microwave absorption.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing material preparation, specifically relating to a composite microwave absorbing material and method derived from MXene / heterometallic MOFs. Background Technology

[0002] In recent years, the widespread use of new electronic devices such as household appliances, wireless base stations, and military radar has accelerated the rate of electromagnetic pollution. Electromagnetic pollution poses a serious threat to human health and national defense security, attracting global attention. For a long time, electromagnetic shielding and electromagnetic absorption have been two typical strategies to address the problems caused by electromagnetic pollution, used to mitigate or resist the adverse effects of residual electromagnetic waves. Electromagnetic absorbing materials, in particular, convert the energy of incident electromagnetic waves into heat or other forms of energy, attenuating or dissipating it.

[0003] Among numerous electromagnetic wave absorbing materials, carbon materials have attracted much attention due to their advantages such as low density, high conductivity, and stable chemical properties. Multilayer MXene, with its unique accordion-like structure, offers a natural structural advantage for multiple reflections of incident electromagnetic waves. Furthermore, the presence of functional groups and defects on the MXene surface makes it an ideal candidate for novel electromagnetic wave absorbing materials. However, MXene as a microwave absorbing material still suffers from poor absorption capacity and a narrow effective absorption bandwidth. Existing research has focused on using MXene as a substrate to construct composite materials by introducing magnetic components, thereby adjusting the electromagnetic parameters of the material, improving impedance matching, and enhancing microwave absorption capacity. For example, Liu et al. (Liu P, Yao Z, Ng VMH, et al. Facilesynthesis of ultrasmall Fe3O4nanoparticles on MXenes for high microwave absorption performance, Composites Part A: Applied Science and Manufacturing, 2018, 115: 371-382.) prepared TiO2 / Ti3C2T using a chemical hydrothermal reaction. x / Fe3O4 composite material. This composite material has an effective absorption bandwidth (EAB) of 2 GHz at a thickness of 1.9 mm and a minimum reflection loss (RL) of 10.1 GHz. min The value is -57.3 dB. It can be inferred that MXene-based composite materials are promising candidates for developing ultrathin and lightweight microwave absorbers.

[0004] Metal-organic frameworks (MOFs) are organic-inorganic hybrid porous crystalline materials composed of organic ligands and metal ions / clusters, possessing advantages such as tunable structure, large specific surface area, and tunable porosity. Due to the wide variety of metal ions / clusters and organic ligands, the resulting MOF materials exhibit diverse morphologies and are easily functionalized. Furthermore, annealed MOFs are composite materials composed of magnetic metal particles and graphitic carbon; modulation of their electromagnetic properties holds promise for improving impedance matching and achieving breakthroughs in microwave absorption performance. Summary of the Invention

[0005] The purpose of this invention is to provide a composite microwave absorbing material and method for preparation of MXene / heterometallic MOFs. The resulting composite microwave absorbing material has good impedance matching and excellent microwave absorption performance with a thin thickness and light weight, and can be applied in the field of microwave absorption.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A composite microwave absorbing material derived from MXene / heterometallic MOFs is prepared by the following steps:

[0008] (1) Preparation of MXene: Ti3AlC2 powder was added to HF solution, heated in a water bath under magnetic stirring, and then the resulting product was centrifuged, washed repeatedly, and dried under vacuum to obtain MXene;

[0009] (2) Preparation of MXene / heterometallic MOFs complex: The MXene obtained in step (1) and heterometallic salt were added to a solvent to obtain solution A; the organic ligand and surfactant were dissolved in a solvent to obtain solution B; under continuous stirring, solution A and solution B were mixed for hydrothermal reaction, and the resulting product was washed and dried to obtain MXene / heterometallic MOFs complex.

[0010] (3) Preparation of MXene / heterometallic MOFs-derived composite absorbing material: The MXene / heterometallic MOFs composite obtained in step (2) is annealed to obtain the MXene / heterometallic MOFs-derived composite absorbing material.

[0011] Furthermore, in step (1), the amount of Ti3AlC2 powder added is 0.1 g / mL.

[0012] Further, the concentration of the HF solution in step (1) is 35~49 wt%.

[0013] Furthermore, the water bath heating in step (1) is at a temperature of 60 °C for 24 h.

[0014] Furthermore, the heterogeneous metal salt mentioned in step (2) is at least two of the following: iron salt, zinc salt, nickel salt, cobalt salt, manganese salt, titanium salt, etc.

[0015] Further, the surfactant mentioned in step (2) is a poly(ethylene oxide-poly(propylene oxide-poly(ethylene oxide)) triblock copolymer (P123), polyvinylpyrrolidone (PVP), or hexadecyltrimethylammonium bromide (CTAB), etc.

[0016] Further, the organic ligand mentioned in step (2) is 2-methylimidazole, terephthalic acid, 1,3,5-benzenetricarboxylic acid, 2,5-dihydroxyterephthalic acid or 1,4-benzenetricarboxylic acid, etc.

[0017] Further, the solvent mentioned in step (2) is at least one of deionized water, methanol, ethanol, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0018] Furthermore, in step (2), the mass ratio of MXene to heterometallic salt is 1:20 to 1:5, the mass ratio of MXene to surfactant is 1:60 to 1:10, and the mass ratio of MXene to organic ligand is 1:6 to 2:3.

[0019] Furthermore, the temperature of the hydrothermal reaction in step (2) is 120~180 ℃ and the time is 6~10 h.

[0020] Further, the annealing treatment in step (3) is carried out in a nitrogen and / or argon atmosphere, with the temperature increased to 400-1000 °C at a rate of 0.5-10 °C / min and held for 1-8 h.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The present invention is subjected to high temperature annealing treatment, which transforms MXene in the composite into amorphous carbon and precipitates TiO2 on the surface, while heterogeneous metal MOFs are transformed into graphite carbon and heterogeneous alloy nanoparticles. The heterogeneous interface formed by the heterogeneous metal components and carbon materials brings multiple loss mechanisms, optimizes impedance matching, and enables the composite material to exhibit excellent microwave absorption capabilities.

[0023] (2) By adjusting the type and mass ratio of metals in heterogeneous metal MOFs, the present invention can control the microstructure and electromagnetic parameters of composite absorbing materials derived from MXene / heterogeneous metal MOFs.

[0024] (3) The preparation method of the present invention is simple, the reaction process is easy to control, and the repeatability is good. It has good application prospects and value. Attached Figure Description

[0025] Figure 1 The XRD patterns of the samples prepared in Examples 1-5 are shown (where a: Ti3AlC2 and MXene, b: MXene / CoNi-MOF series, c: MXene / CoNi / C series).

[0026] Figure 2 This is a SEM image of the MXene prepared in Example 1.

[0027] Figure 3 SEM images of the Co1Ni1-MOF and MXene / CoNi-MOF series composites prepared in Examples 1-5 (where, a: Co1Ni1-MOF, b: MXene / Co1Ni4-MOF, c: MXene / Co1Ni1-MOF, d: MXene / Co4Ni1-MOF, e: MXene / Co1Ni1-MOF-1, f: MXene / Co1Ni1-MOF-2).

[0028] Figure 4 SEM images of the Co1Ni1 / C and MXene / CoNi / C series complexes prepared in Examples 1-5 (where a: Co1Ni1 / C, b: MXene / Co1Ni4 / C, c: MXene / Co1Ni1 / C, d: MXene / Co4Ni1 / C, e: MXene / Co1Ni1 / C-1, f: MXene / Co1Ni1 / C-2).

[0029] Figure 5 The image shows a TEM image of the MXene / Co1Ni1 / C prepared in Example 1.

[0030] Figure 6 This is the EDS mapping diagram of MXene / Co1Ni1 / C prepared in Example 1.

[0031] Figure 7 The reflection loss diagrams and attenuation constant curves of the MXene / CoNi / C series composites prepared in Examples 1-5 are shown (where, a: a-MXene; b: Co1Ni1 / C, c: MXene / Co1Ni4 / C, d: MXene / Co1Ni1 / C, e: MXene / Co4Ni1 / C, f: MXene / Co1Ni1 / C-1, g: MXene / Co1Ni1 / C-2, h: attenuation constant curve).

[0032] Figure 8 The image shows the hysteresis loop diagram of MXene / Co1Ni1 / C prepared in Example 1.

[0033] Figure 9The images show the XRD patterns of the MXene / CoFe-MOF series complexes and MXene / CoFe / C series complexes prepared in Examples 6-8.

[0034] Figure 10 SEM images of the MXene / CoFe-MOF series complexes and MXene / CoFe / C series complexes prepared in Examples 6-8 (where, a: MXene / Co1Fe3-MOF, b: MXene / Co1Fe1-MOF, c: MXene / Co3Fe1-MOF, d: MXene / Co1Fe3 / C, e: MXene / Co1Fe1 / C, f: MXene / Co3Fe1 / C).

[0035] Figure 11 The reflection loss diagrams are for the MXene / CoFe / C series composites prepared in Examples 6-8 (where a1-a3: MXene / Co1Fe3 / C, b1-b3: MXene / Co1Fe1 / C, c1-c3: MXene / Co3Fe1 / C). Detailed Implementation

[0036] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0037] Example 1:

[0038] (1) Preparation of MXene: 1 g of Ti3AlC2 (98%) powder was added to 10 mL of 49 wt% HF solution in small amounts several times, heated to 60 °C in a water bath, and magnetically stirred for 24 h. Subsequently, the product after reaction was centrifuged, washed several times with deionized water, and the resulting black precipitate was vacuum dried at 60 °C for 24 h to obtain MXene.

[0039] A portion of the obtained MXene was heated from room temperature to 800 ℃ at a rate of 5 ℃ / min under a nitrogen atmosphere and held for 2 h. The resulting annealed sample was named α-MXene as a control.

[0040] (2) Preparation of MXene / Co1Ni1-MOF composite: 0.25 g Co(NO3)2·6H2O, 0.25 g Ni(NO3)2·6H2O and 0.05 g MXene were added to a mixed solution of N,N-dimethylformamide (DMF) and ethanol (volume ratio 1:1) and sonicated for 10 min to obtain solution A; 0.15 g terephthalic acid (PTA) and 1.0 g polyvinylpyrrolidone (PVP) were added to a mixed solution of DMF and ethanol (volume ratio 1:1) and sonicated for 10 min to obtain solution B; under continuous magnetic stirring, solution B was slowly added dropwise to solution A, and the mixture was hydrothermally reacted at 150 ℃ for 10 h to obtain a gray solution; the gray solution was then washed three times with ethanol, and the resulting sample was dried in a vacuum oven at 60 ℃ for 24 h. The dried product was named MXene / Co1Ni1-MOF.

[0041] (3) Preparation of MXene / Co1Ni1 / C composite material: The obtained MXene / Co1Ni1-MOF was heated from room temperature to 800 ℃ at a rate of 5℃ / min under nitrogen atmosphere and held for 2 h. The annealed product was named MXene / Co1Ni1 / C.

[0042] In addition, Co1Ni1-MOF and Co1Ni1 / C were prepared as controls according to steps (2) and (3) without the addition of MXene.

[0043] Example 2:

[0044] The amounts of Co(NO3)2·6H2O and Ni(NO3)2·6H2O in step (2) were adjusted to 0.1 g and 0.4 g, respectively. Other operations were the same as in Example 1. The resulting complex was named MXene / Co1Ni4-MOF, and the annealed product was named MXene / Co1Ni4 / C.

[0045] Example 3:

[0046] The amounts of Co(NO3)2·6H2O and Ni(NO3)2·6H2O in step (2) were adjusted to 0.4 g and 0.1 g, respectively. Other operations were the same as in Example 1. The resulting complex was named MXene / Co4Ni1-MOF, and the annealed product was named MXene / Co4Ni1 / C.

[0047] Example 4:

[0048] The amount of MXene in step (2) was adjusted to 0.1 g, and other operations were the same as in Example 1. The resulting complex was named MXene / Co1Ni1-MOF-1, and the annealed product was named MXene / Co1Ni1 / C-1.

[0049] Example 5:

[0050] The amount of MXene in step (2) was adjusted to 0.025 g, and other operations were the same as in Example 1. The resulting complex was named MXene / Co1Ni1-MOF-2, and the annealed product was named MXene / Co1Ni1 / C-2.

[0051] Example 6:

[0052] (1) Prepare MXene according to step (1) of Example 1.

[0053] (2) Preparation of MXene / Co1Fe1-MOF composite: 0.4 g Co(NO3)2·6H2O, 0.4 g FeCl3·6H2O and 0.05 g MXene were added to a mixed solution of N,N-dimethylformamide (DMF) and ethanol (volume ratio 1:1) and sonicated for 10 min to obtain solution A; 0.24 g terephthalic acid (PTA) and 3.0 g polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) were added to a mixed solution of DMF and ethanol (volume ratio 1:1) and sonicated for 10 min to obtain solution B; under continuous magnetic stirring, solution B was slowly added dropwise to solution A, and the mixture was hydrothermally reacted at 150 ℃ for 10 h to obtain a gray solution; then the gray solution was washed three times with ethanol, and the obtained sample was dried in a vacuum oven at 60 ℃ for 24 hours. h, the dried product was named MXene / Co1Fe1-MOF.

[0054] (3) Preparation of MXene / Co1Fe1 / C composite material: The obtained MXene / Co1Fe1-MOF was heated from room temperature to 800 ℃ at a rate of 5℃ / min under nitrogen atmosphere and held for 2 h. The annealed product was named MXene / Co1Fe1 / C.

[0055] Example 7:

[0056] The amounts of Co(NO3)2·6H2O and FeCl3·6H2O in step (2) were adjusted to 0.2 g and 0.6 g, respectively. Other operations were the same as in Example 6. The resulting complex was named MXene / Co1Fe3-MOF, and the annealed product was named MXene / Co1Fe3 / C.

[0057] Example 8:

[0058] The amounts of Co(NO3)2·6H2O and FeCl3·6H2O in step (2) were adjusted to 0.6 g and 0.2 g, respectively. Other operations were the same as in Example 6. The resulting complex was named MXene / Co3Fe1-MOF, and the annealed product was named MXene / Co3Fe1 / C.

[0059] The samples obtained in Examples 1-8 above were characterized using field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and vector network analyzer (VNA). Specific test results are as follows: Figures 1-10 As shown.

[0060] Figure 1 The XRD patterns of the samples prepared in Examples 1-5 are shown. As can be seen from the figures, compared to Ti3AlC2, all diffraction peaks of MXene are wider and weaker, and the diffraction peak at 39° almost disappears, proving that the Al layer was successfully etched. The characteristic peaks of a-MXene obtained by direct annealing at 25.36° and 27.44° correspond to the (101) crystal plane of anatase TiO2 (JCPDS No. 84-1285) and rutile TiO2 (JCPDS No. 99-0090), respectively. Meanwhile, CoNi-MOF shows characteristic peaks of the (200), (001), and (201) crystal planes at 8.85°, 15.9°, and 17.9°. Furthermore, the characteristic peaks of both MXene and CoNi-MOF appear in the MXene / CoNi-MOF series composites, indicating the successful preparation of the composite material. After annealing, characteristic peaks of CoNi alloy at 44.5 °, 51.8 °, and 76.2 °, as well as characteristic peaks of rutile TiO2 or anatase TiO2, appeared in the MXene / CoNi / C series composites. These analyses demonstrate the successful preparation of MXene, α-MXene, CoNi-MOF, MXene / CoNi-MOF series composites, and MXene / CoNi / C series composites.

[0061] Figure 2 The image shows a SEM image of the MXene prepared in Example 1. As can be seen from the image, the MXene exhibits a distinct accordion shape with a certain spacing between the layers.

[0062] Figure 3 SEM images of the Co1Ni1-MOF and MXene / CoNi-MOF series composites prepared in Examples 1-5 are shown. As shown in the figure, Co1Ni1-MOF exhibits a hydrangea-like appearance (a); while after being combined with MXene, the Co1Ni1-MOF... 2+With increasing proportion, the CoNi-MOF in the composite changes from spherical to multilayered nanosheets, and the size becomes larger and larger (bd); when the amount of MXene increases, the morphology of MOF in the composite also changes from small-sized nano-pollen shape (f) to large-sized nano-cube shape (e).

[0063] Figure 4 The images show SEM images of the Co1Ni1 / C and MXene / CoNi / C series composites prepared in Examples 1-5. As can be seen from the images, after carbonization, MXene in MXene / CoNi-MOF still maintains an accordion-like lamellar structure, while the CoNi alloy derived from CoNi-MOF and amorphous C form embroidered ball-like or nanoflower-like structures formed by the self-assembly of multiple nanosheets (Figures b-f).

[0064] Figure 5 The image shows a TEM image of the MXene / Co1Ni1 / C prepared in Example 1. The image clearly shows the lattice fringes of TiO2, CoNi alloy, and graphite carbon in the composite.

[0065] Figure 6 The image shows the EDS mapping of the MXene / Co1Ni1 / C prepared in Example 1. As can be seen from the image, the composite contains Ti, C, Co, Ni, and O elements.

[0066] Figure 7 The figures show the reflection loss and attenuation constant curves of the MXene / CoNi / C series composites prepared in Examples 1-5. It can be seen from the figures that a-MXene has poor absorption performance, with a minimum reflection loss (RL) of [missing value]. min The absorption performance is only -14.6 dB(a); Co1Ni1 / C has slightly higher absorption performance than a-MXene, RL min The value was -17.5 dB, which was not ideal (b). When CoNi-MOF was combined with MXene, the MXene / Co1Ni1 / C composite exhibited the best absorption performance with a minimum reflection loss of -61.34 dB and a maximum effective absorption bandwidth of 5.2 GHz when the Co / Ni molar ratio was 1:1, increasing or decreasing the proportion of MXene in the composite significantly worsened its absorption performance (fg). The attenuation constant curves of the samples show that each sample exhibited a certain attenuation performance (h).

[0067] Figure 8 The image shows the hysteresis loop of MXene / Co1Ni1 / C prepared in Example 1. As can be seen from the image, MXene / Co1Ni1 / C... MThe s value is 17.45 emu / g, indicating weak magnetism.

[0068] Figure 9 The XRD patterns of the MXene / CoFe-MOF series composites and MXene / CoFe / C series composites prepared in Examples 6-8 are shown. As can be seen from the figures, the characteristic diffraction peaks of MXene and CoFe-MOF appear in MXene / CoFe-MOF, indicating the successful synthesis of the composite material. The characteristic diffraction peaks of the MXene / CoFe / C series composites after carbonization at 44.82° and 65.26° correspond to the (110) and (200) crystal planes of the CoFe alloy, respectively. Furthermore, the typical peaks at 27.4°, 36.1°, 41.2°, and 54.3° correspond to the (110), (101), (111), and (211) crystal planes of rutile titanium dioxide. All the above analyses prove that the MXene / CoFe-MOF series composites and MXene / CoFe / C series composites were successfully prepared.

[0069] Figure 10 SEM images of the MXene / CoFe-MOF series composites and MXene / CoFe / C series composites prepared in Examples 6-8 are shown. As can be seen from the images, the CoFe-MOF in MXene / Co1Fe3-MOF and MXene / Co3Fe1-MOF are small particles, coated on the surface of MXene (a, c); while in MXene / Co1Fe1-MOF, the Co1Fe1-MOF exhibits a rod-like structure with pyramidal ends, loaded on the surface of MXene (b). After annealing, the MXene in MXene / CoFe-MOF transforms into graphite carbon sheets and TiO2, with the graphite carbon sheets retaining an accordion shape; the CoFe-MOF particles transform into CoFe alloy particles and amorphous C. Due to the small size of Co1Fe3-MOF and Co3Fe1-MOF, some particles are embedded between the layers of MXene (df).

[0070] Figure 11 The figures show the reflection loss diagrams of the MXene / CoFe / C series composites prepared in Examples 6-8. As can be seen from the figures, the reflection loss ratio (RL) of MXene / Co1Fe3 / C at a thickness of 3.2 mm is... min The value is -14.2 dB, RL for MXene / Co1Fe3 / C at a thickness of 1.6 mm. min The value was -18.1 dB, indicating poor microwave absorption performance for both. However, the RL of MXene / Co1Fe1 / C at a thickness of 1.5 mm was significantly lower. minThe value can reach -40 dB, with an effective absorption bandwidth of 3.12 GHz, exhibiting excellent microwave absorption performance.

[0071] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing composite microwave absorbing materials derived from MXene / heterometallic MOFs, characterized in that, Includes the following steps: (1) Preparation of MXene: Ti3AlC2 powder was added to HF solution, heated in a water bath under magnetic stirring, and then the resulting product was centrifuged, washed repeatedly, and dried under vacuum to obtain MXene; (2) Preparation of MXene / heterometallic MOFs complex: The MXene obtained in step (1) and heterometallic salt were added to a solvent to obtain solution A; the organic ligand and surfactant were dissolved in a solvent to obtain solution B; under continuous stirring, solution A and solution B were mixed for hydrothermal reaction, and the resulting product was washed and dried to obtain MXene / heterometallic MOFs complex. (3) Preparation of MXene / heterometallic MOFs-derived composite absorbing material: The MXene / heterometallic MOFs composite obtained in step (2) is annealed to obtain the MXene / heterometallic MOFs-derived composite absorbing material. The heterometallic salts mentioned in step (2) are nickel salts and cobalt salts; the organic ligand is terephthalic acid; the surfactant is polyvinylpyrrolidone; and the mass ratio of MXene to heterometallic salt is 1:10, the mass ratio of MXene to surfactant is 1:20, and the mass ratio of MXene to organic ligand is 1:

3.

2. The method for preparing composite absorbing materials derived from MXene / heterometallic MOFs according to claim 1, characterized in that, In step (1), the amount of Ti3AlC2 powder added is 0.1 g / mL; the concentration of the HF solution is 35~49 wt%.

3. The method for preparing composite microwave absorbing materials derived from MXene / heterometallic MOFs according to claim 1, characterized in that, The water bath heating in step (1) is at a temperature of 60 °C for 24 h.

4. The method for preparing composite absorbing materials derived from MXene / heterometallic MOFs according to claim 1, characterized in that, The solvent mentioned in step (2) is at least one of deionized water, methanol, ethanol, N,N-dimethylformamide, and N,N-dimethylacetamide.

5. The composite microwave absorbing material and method prepared by MXene / heterometallic MOFs derivation according to claim 1, characterized in that: The hydrothermal reaction in step (2) is carried out at a temperature of 120~180 ℃ for 6~10 h.

6. The method for preparing composite absorbing materials derived from MXene / heterometallic MOFs according to claim 1, characterized in that, The annealing process described in step (3) involves heating the gas to 400-1000 °C at a rate of 0.5-10 °C / min in a nitrogen and / or argon atmosphere and holding it for 1-8 h.

7. An MXene / heterometallic MOFs-derived composite microwave absorbing material prepared by the method described in any one of claims 1 to 6.

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