Zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave absorbing material and preparation method and application thereof

Abstract

The present invention discloses a wave absorbing material with a zero-dimensional / one-dimensional / two-dimensional composite nanostructure, comprising a two-dimensional MXene, a zero-dimensional metal particle, and a one-dimensional carbon nanotube, wherein zero-dimensional metal particles are simultaneously loaded on the surface of the two-dimensional MXene, and the one-dimensional carbon nanotube is grown in situ. The wave absorbing material has a relatively superior maximum reflectivity and absorption bandwidth. The present invention also provides a method for preparing a wave absorbing material with a zero-dimensional / one-dimensional / two-dimensional composite nanostructure. The preparation method is simple and efficient and is suitable for large-scale industrial production. The present invention also provides the application of the wave absorbing material with a zero-dimensional / one-dimensional / two-dimensional composite nanostructure in the fields of military stealth and civilian electromagnetic protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave absorbing materials, and in particular relates to a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material and a preparation method and application thereof. Background Art

[0002] With the rapid development of information technology, especially the advent of the 5G era, electronic devices are widely used in daily life. However, electronic devices can also cause serious electromagnetic pollution, which not only affects human health, but also causes electronic devices to malfunction and degrade in civilian or military applications. Therefore, the demand for absorbing materials is increasing.

[0003] Traditional absorbing materials include ferrite, barium titanate, metal powder, graphite, silicon carbide, conductive fiber, etc. They usually have disadvantages such as narrow absorption band, high density, large filling rate, and easy oxidation, which limit their practical application.

[0004] With the rapid development of science and technology, traditional absorbing materials can no longer meet the current demand for sharply increased frequencies. Exploring new "wide, thin, light, and strong" absorbing materials is a research direction in this field. Recent research results show that cleverly designing special structures with adjustable electromagnetic parameters is a feasible strategy to improve microwave absorption performance.

[0005] The Chinese patent with publication number CN111629575A discloses a method for preparing a MXene-based nanocomposite absorbing material, which is prepared by the following steps: mixing and pre-treating the MXene prepared by etching with a metal salt, irradiating the pre-treated mixed solution, and then post-treating the MXene-based nanocomposite absorbing material. The patent introduces magnetic nanoparticles to evenly load the surface of the MXene material, thereby improving the impedance matching of the composite material. Therefore, the MXene-based nanocomposite absorbing material has a maximum reflection loss of 28dB and an effective absorption bandwidth of 2.65GHz.

[0006] A Chinese patent with publication number CN107645065A discloses a method for preparing an onion carbon / MXene layered absorbing composite material: titanium silicon carbon is used as raw material, after being corroded by hydrofluoric acid of different concentrations, it is washed with deionized water and then dried to obtain a MXene material; then the prepared MXene material is uniformly dispersed in deionized water by an ultrasonic dispersion method to obtain a suspension of the MXene material; the onion carbon nanomaterial is uniformly dispersed in deionized water by an ultrasonic dispersion method to obtain a suspension of the onion carbon nanomaterial; the MXene material suspension solution and the onion carbon material suspension solution are filtered alternately to obtain an onion carbon / MXene layered absorbing composite material; the prepared onion carbon / MXene layered absorbing composite material has a light weight, a thin thickness, and has a better reflectivity within the microwave frequency range.

[0007] However, the relatively simple material structure design / composite of the absorbing composite materials disclosed in the above two patents has limited improvement on the absorbing performance of the materials, and their absorption intensity and effective bandwidth are both small. Based on this, it is urgent to design a composite nanostructured high-efficiency absorbing material with superior lightweight and broadband absorbing performance. Summary of the invention

[0008] The invention provides a zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave-absorbing material, which has superior maximum reflectivity and absorption bandwidth.

[0009] A zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material comprises two-dimensional MXene, zero-dimensional metal particles, and one-dimensional carbon nanotubes, wherein the zero-dimensional metal particles are simultaneously loaded on the surface of the two-dimensional MXene, and the one-dimensional carbon nanotubes are grown in situ.

[0010] In the composite material of zero-dimensional Co particles, one-dimensional carbon nanotubes (CNTs) and two-dimensional MXene in the present invention, the electrons at the heterogeneous interface of the zero-dimensional / one-dimensional / two-dimensional materials are very likely to form an interface polarization consumption center of electromagnetic loss at the heterogeneous interface due to the difference between the work functions of the materials in which they are located, which greatly promotes the consumption of the incident electromagnetic wave. In addition, due to the large number of defects in CNTs and MXene that will lead to dipole polarization, and the electronic transition in the MXene / CNTs conductive network can cause conduction loss, the multi-scattering reflection and scattering between the MXene sheet and CNTs also help to attenuate electromagnetic waves; the zero-dimensional metal particles can optimize the impedance matching of the absorber and provide magnetic loss, so that higher high-frequency wave absorption characteristics can be achieved at low filling rates.

[0011] The general formula of the two-dimensional MXene is M n+1 X n T, wherein M is a transition metal Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta or W; X is carbon and / or nitrogen; T is an O, F or OH functional group; wherein n is 1, 2, or 3.

[0012] The zero-dimensional metal is Fe, Co or Ni.

[0013] The present invention also provides a method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave absorbing material, comprising:

[0014] The two-dimensional MXene is dispersed in an organic solution to obtain a two-dimensional MXene organic solution, a metal salt is added to the two-dimensional MXene organic solution, and a mixed solution A is obtained by ultrasonic treatment; an appropriate amount of organic ligand is dissolved in a certain organic solution and then added to the above solution A. Finally, the mixed solution is stirred, allowed to stand, and dried to obtain MOF / MXene; the MOF / MXene is carbonized at high temperature to obtain a zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave absorbing material.

[0015] The organic solution is monohydric alcohol, dihydric alcohol or polyhydric alcohol and a mixed solvent thereof.

[0016] The metal salt is nitrate, sulfate, carbonate, acetate or chloride.

[0017] The organic ligand is 2-methylimidazole, 2-imidazole carboxaldehyde, 4-bromoimidazole, imidazole, benzimidazole, terephthalic acid, trimesic acid, and naphthalene tetracarboxylic anhydride.

[0018] The molar ratio of the metal salt to the organic ligand is 1:4-10. A molar ratio that is too high will cause the MOF particles to grow in an irregular shape, and a molar ratio that is too low will cause the MOF nucleation to be slow, which is not conducive to electrostatic adsorption and composite on the two-dimensional MXene.

[0019] The stirring time is 5-10 minutes, and the standing time is 3-5 hours.

[0020] The solvent thermal reaction parameters are: reaction temperature is 60-200°C, and reaction time is 8-24h.

[0021] The high temperature carbonization process is as follows: in an Ar / H2 atmosphere, the temperature is increased to 700-900°C at a rate of 2-10°C / min, and the carbonization time is 2-8h.

[0022] Furthermore, the volume ratio of Ar to H2 is 95%:5% vol / vol. The purpose of adding H2 is to improve the reducing property of the high temperature atmosphere, which is helpful to obtain Co particles and CNTs.

[0023] The present invention also provides the application of the zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave-absorbing material in the fields of military stealth and civilian electromagnetic protection.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention utilizes the interfacial polarization between zero-dimensional metal particles, one-dimensional carbon nanotubes, and two-dimensional MXene. At the same time, a large number of defects in CNTs and MXene will lead to dipole polarization, conduction loss caused by electronic transitions in the MXene / CNTs conductive network, and multi-scattering reflection and scattering between MXene sheets and CNTs also help to attenuate electromagnetic waves. In addition, the presence of zero-dimensional metal magnetic particles in the composite material can optimize the impedance matching of the absorber and provide magnetic loss, thereby further improving and optimizing the high-frequency wave absorption characteristics of the material at a low filling rate. This structure can achieve efficient broadband absorption of electromagnetic waves and achieve efficient absorption. The prepared zero-dimensional / one-dimensional / two-dimensional composite nanostructure shows excellent lightweight broadband absorption performance at 2-18GHz, with a maximum reflectivity of -50.5dB and an effective absorption bandwidth of 3.2GHz.

[0026] (2) The preparation method provided by the present invention is simple, efficient and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of SEM and TEM of Co@C / Ti2C MXene with zero-dimensional / one-dimensional / two-dimensional structure prepared in Example 1, where Figure 1 (a) is the SEM image of Co@C / Ti2C MXene. Figure 1 (b) TEM image of Co@C / Ti2C MXene;

[0028] Figure 2 XRD characterization diagram of Co@C / Ti2C MXene with zero-dimensional / one-dimensional / two-dimensional structure prepared in Example 1;

[0029] Figure 3 Schematic diagram of reflection loss curve of Co@C / Ti2C MXene with zero-dimensional / one-dimensional / two-dimensional structure prepared in Example 1;

[0030] Figure 4 Schematic diagram of reflection loss curve of Ni@C / Nb2C MXene with zero-dimensional / one-dimensional / two-dimensional structure prepared in Example 2;

[0031] Figure 5 Schematic diagram of reflection loss curve of Fe@C / V2C MXene with zero-dimensional / one-dimensional / two-dimensional structure prepared in Example 3;

[0032] Figure 6 Schematic diagram of the reflection loss curve of Ti2C MXene prepared in Comparative Example 1;

[0033] Figure 7Schematic diagram of the reflection loss curve of Co@C prepared in comparative example 2. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments.

[0035] Example 1

[0036] A method for preparing a zero-dimensional / one-dimensional / two-dimensional Co@C / MXene composite material with high efficiency microwave absorption comprises the following steps:

[0037] (I) Preparation of Ti2C MXene

[0038] At room temperature, weigh 2g LiF powder and pour it into 40ml HCl (AR), stir at 350r / min for 40min at room temperature, then pour 2g MAX phase powder Ti3AlC2 into the above solution, water bath at 35℃, and stir at 250r / min for 24h. The obtained solution was repeatedly centrifuged and washed with deionized water until pH>6. Then the obtained precipitate was diluted in a 500ml beaker, ultrasonicated for 3h, centrifuged to take the supernatant, and finally dried with a freeze dryer to obtain a single-layer Ti2C MXene powder.

[0039] (II) Preparation of Co-MOF / Ti2C MXene

[0040] 10 mg of the single-layer Ti2C MXene prepared in the above (a) was weighed and dissolved in 20 ml of methanol solution, and 1 mmol of Co(NO3)2·6H2O was added, and ultrasonic treatment was performed for 1 h to obtain a mixed solution A; at the same time, 8 mmol of 2-methylimidazole was dissolved in 20 ml of methanol solution and stirred for 45 min to obtain a mixed solution B; under stirring, A was poured into B, stirred for 2 h, and then allowed to stand overnight, and Co-MOF / MXene was obtained by freeze drying.

[0041] (III) Preparation of Co@C / Ti2C MXene

[0042] The Co-MOF / Ti2C MXene powder prepared in (ii) above was placed in a tube furnace, heated to 800°C at a rate of 5°C / min in an Ar / H2 atmosphere and kept at that temperature for 4 h. After natural cooling, the powder was collected to obtain Co@C / Ti2C MXene. SEM and TEM results showed that ( Figure 1 a and b), the Co@C / Ti2C MXene prepared in Example 1 has a significant 0D (metal particles) / 1D (carbon nanotubes) / 2D (MXene material) structure nanocomposite structure; at the same time, the XRD results show that ( Figure 2), the prepared Co@C / Ti2C MXene has a significant diffraction peak of metal Co particles, confirming the existence of metal particles.

[0043] Example 2

[0044] A method for preparing a high-efficiency microwave absorbing composite material 0D / 1D / 2D Ni@C / Nb2C MXene comprises the following steps:

[0045] (I) Preparation of Nb2C MXene

[0046] The process is basically the same as step (I) in Example 1, except that the Ti3AlC2 MAX phase powder in step (I) is replaced by Nb3AlC2 MAX phase powder to prepare Nb2CMXene.

[0047] (II) Preparation of Ni-MOF / Nb2C MXene

[0048] 10 mg of the single-layer Nb2C MXene prepared in the above (a) was weighed and dissolved in 20 ml of methanol solution, and 1 mmol of Ni(NO3)2·6H2O was added, and the mixture was treated by ultrasound for 1 h to obtain a mixed solution A. At the same time, 8 mmol of 2-methylimidazole was dissolved in 20 ml of methanol solution and stirred for 45 min to obtain a mixed solution B. Under stirring conditions, A was poured into B, and after stirring for 10 min, the mixed solution was transferred to a 50 ml reactor and heated to 120°C for 12 h. After centrifugal washing, Ni-MOF / Nb2CMXene was obtained by freeze drying.

[0049] (III) Preparation of Ni@C / Nb2C MXene

[0050] The Ni-MOF / MXene powder prepared in the above (ii) was placed in a tubular furnace, and the temperature was raised to 800°C at a heating rate of 5°C / min under an Ar / H2 atmosphere and kept for 4 hours. After natural cooling, the powder was collected to obtain Ni@C / MXene.

[0051] Example 3

[0052] A method for preparing a high-efficiency microwave absorbing composite material 0D / 1D / 2D Fe@C / V2C MXene comprises the following steps:

[0053] (I) Preparation of V2C MXene

[0054] The process is basically the same as step (i) in Example 1, except that the Ti3AlC2 MAX phase powder in step (i) is replaced with V3AlC2 MAX phase powder to prepare V2C MXene.

[0055] (II) Preparation of Fe-MOF / V2C MXene

[0056] 10 mg of the single-layer V2C MXene prepared in the above (a) was weighed and dissolved in 20 ml of methanol solution, and 1 mmol of Fe(NO3)2·6H2O was added, and the mixture was treated by ultrasound for 1 h to obtain a mixed solution A. At the same time, 8 mmol of 2-methylimidazole was dissolved in 20 ml of methanol solution and stirred for 45 min to obtain a mixed solution B. Under stirring conditions, A was poured into B, and after stirring for 10 min, the mixed solution was transferred to a 50 ml reactor and heated to 80°C for 12 h. After centrifugal washing, Fe-MOF / V2CMXene was obtained by freeze drying.

[0057] (III) Preparation of Fe@C / V2C MXene

[0058] The Fe-MOF / V2C MXene powder prepared in the above (ii) was placed in a tubular furnace, and heated to 800°C at a heating rate of 5°C / min under an Ar / H2 atmosphere and kept for 4 hours. After natural cooling, the powder was collected to obtain Fe@C / V2C MXene.

[0059] Comparative Example 1

[0060] The preparation steps are the same as step (i) in Example 1, except that only Ti2CMXene is prepared, and the subsequent MOF growth and catalytic cracking steps are not included.

[0061] Comparative Example 2

[0062] The preparation steps are basically the same as those in Example 1, except that Ti2C MXene is not added. The preparation process is named Co@C. The specific preparation steps are as follows:

[0063] (I) Preparation of Co-MOF

[0064] 1 mmol Co(NO3)2·6H2O was added to 20 ml methanol solution and treated with ultrasound for 1 h to obtain mixed solution A; at the same time, 8 mmol 2-methylimidazole was dissolved in 20 ml methanol solution and stirred for 45 min to obtain mixed solution B; under stirring, A was poured into B, and after stirring for 10 min, the mixed solution was transferred to a 50 ml reactor and heated to 120°C for 12 h. After centrifugal washing, Ni-MOF was obtained by freeze drying.

[0065] (II) Preparation of Co@C

[0066] The Co-MOF powder prepared in the second step was placed in a tubular furnace, and in an Ar / H2 atmosphere, the temperature was raised to 800°C at a heating rate of 5°C / min and kept for 4 h. After natural cooling, the powder was collected to obtain Co@C.

[0067] Application Examples

[0068] The above-mentioned zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material is mixed into silica gel according to a certain mass ratio, and after uniform stirring, it is coated by casting to form a film. After drying, it is cast multiple times on the basis of this film to prepare an electromagnetic absorbing patch of a certain thickness. Finally, the obtained absorbing patch is cut into a customized size and shape, and affixed to the target electromagnetic source to achieve the purpose of electromagnetic protection. In terms of civilian use, taking sub-6G communication mobile phones as an example (the current frequency band is 4.5-5GHz, and the loss capacity is <-10dB), in order to ensure the normal communication of the mobile phone, the above-prepared absorbing patch is affixed to the relevant position of the electromagnetic path in the mobile phone, which can effectively reduce the crosstalk of the internal high-frequency signal, achieve the electromagnetic compatibility of the working frequency band, and improve the purpose of communication quality. In terms of military use, the current operating frequency of military fire control and target tracking radars is mostly in the X-band (the frequency range is 8-12GHz, and its wavelength is below 3 cm). The absorbing material is affixed to the corresponding electromagnetic overflow of the radar, so that the radar can be effectively invisible and the radar battlefield survivability can be improved.

[0069] Performance characterization:

[0070] The absorbing materials prepared in the above-mentioned Examples 1 to 3 and Comparative Examples 1-2 were uniformly mixed with molten paraffin at a mass ratio of 1:1 (i.e., the absorbent content was 50%), and pressed into standard coaxial ring samples with an inner diameter of 3.0 mm, an outer diameter of 7.0 mm, and a thickness of 2.0 mm in a special mold. The magnetic and electric properties of the samples were tested for electromagnetic waves within 2-18 GHz using a vector network analyzer (VNA; model: Agilent N5234A) using a coaxial method.

[0071] The electromagnetic wave absorption performance of the sample prepared by using the Co@C / Ti2C MXene absorbing material described in Example 1 is as follows: Figure 3 When the matching thickness is 2.0mm, its effective bandwidth in the 2-18GHz frequency band is 3.2GHz, and the maximum reflectivity is -50dB;

[0072] The electromagnetic wave absorption performance of the sample prepared by using the Ni@C / Nb2C MXene absorbing material described in Example 2 is as follows: Figure 4 When the matching thickness is 2.0 mm, its effective bandwidth is 4.0 GHz in the 2-18 GHz frequency band, and the maximum reflectivity is -42 dB.

[0073] The electromagnetic wave absorption performance of the sample prepared by using the Fe@C / V2C MXene absorbing material described in Example 3 is as follows: Figure 5 When the matching thickness is 2.0 mm, its effective bandwidth in the 2-18 GHz frequency band is 3.2 GHz, and the maximum reflectivity is -43 dB.

[0074] The electromagnetic wave absorption performance of the sample prepared by using the Ti2C MXene absorbing material described in Comparative Example 1 is as follows: Figure 6 When the matching thickness is 2.0 mm, its effective bandwidth is 0 GHz in the 2-18 GHz frequency band, and the maximum reflectivity is -7.3 dB.

[0075] The electromagnetic wave absorption performance of the sample prepared by using the Co@C absorbing material described in Comparative Example 1 is as follows: Figure 7 When the matching thickness is 2.0 mm, its effective bandwidth is 0 GHz in the 2-18 GHz frequency band, and the maximum reflectivity is -8.8 dB.

[0076] The above-described embodiments merely express the implementation methods of the present invention and are not to be construed as limiting the scope of the present invention. It should be noted that all equivalent changes or modifications made according to the present invention should be included in the protection scope of the present invention.

Claims

1. A zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave absorbing material, characterized in that: It includes two-dimensional MXene, zero-dimensional metal particles, and one-dimensional carbon nanotubes, wherein the zero-dimensional metal particles are loaded on the surface of the two-dimensional MXene, and the one-dimensional carbon nanotubes are grown in situ; The method for preparing the zero-dimensional / one-dimensional / two-dimensional composite nanostructured wave absorbing material comprises: The two-dimensional MXene is dispersed in an organic solution to obtain a two-dimensional MXene organic solution, a metal salt is added to the two-dimensional MXene organic solution, and a mixed solution is obtained by ultrasound. An organic ligand is added to the mixed solution, and the mixture is stirred, allowed to stand, and freeze-dried to obtain MOF / MXene; and the MOF / MXene is carbonized at a high temperature to obtain a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material.

2. The zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The general formula of the two-dimensional MXene is M n+1 X n T, wherein M is a transition metal Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta or W; X is carbon and / or nitrogen; T is an O, F or OH functional group; wherein n is 1, 2, or 3.

3. The zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The zero-dimensional metal is Fe, Co or Ni.

4. The method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The organic solution is monohydric alcohol, dihydric alcohol or polyhydric alcohol and a mixed solvent thereof.

5. The method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The metal salt is nitrate, sulfate, carbonate, acetate or chloride.

6. The method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The organic ligand is 2-methylimidazole, 2-imidazole carboxaldehyde, 4-bromoimidazole, imidazole, benzimidazole, terephthalic acid, trimesic acid or naphthalene tetracarboxylic anhydride.

7. The method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The molar ratio of the metal salt to the organic ligand is 1:4-10.

8. The method for preparing a zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to claim 1, characterized in that: The high temperature carbonization process is as follows: in an Ar / H2 atmosphere, the temperature is increased to 700-900°C at a rate of (2-10) / min, and the carbonization time is 2-8h.

9. Application of the zero-dimensional / one-dimensional / two-dimensional composite nanostructured absorbing material according to any one of claims 1 to 3 in the fields of military stealth and civilian electromagnetic protection.

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