CN114501966A - Absorbing material with zero-dimensional/one-dimensional/two-dimensional composite nanostructure and its preparation method and application - Google Patents

Abstract

The invention discloses a zero-dimensional/one-dimensional/two-dimensional composite nano-structure type wave-absorbing material which comprises two-dimensional MXene, zero-dimensional metal particles and a one-dimensional carbon nano tube, wherein the zero-dimensional metal particles are loaded on the surface of the two-dimensional MXene simultaneously, and the one-dimensional carbon nano tube grows in situ. The wave-absorbing material has superior maximum reflectivity and absorption bandwidth. The invention also provides a preparation method of the wave-absorbing material with the zero-dimensional/one-dimensional/two-dimensional composite nanostructure. The preparation method is simple and efficient, and is suitable for large-scale industrial production. The invention also provides the application of the wave-absorbing material with the zero-dimension/one-dimension/two-dimension composite nano structure in the fields of military stealth and civil electromagnetic protection.

Description

Absorber with zero-dimensional/one-dimensional/two-dimensional composite nanostructure and its preparation method and application

technical field

The invention belongs to the technical field of microwave absorbing materials, and in particular relates to a zero-dimensional/one-dimensional/two-dimensional composite nano-structure type wave-absorbing material and a preparation method and application thereof.

Background technique

With the rapid development of information technology, especially the advent of the 5G era, electronic devices are widely used in daily life. But electronic equipment can also cause serious electromagnetic pollution, which not only affects human health, but also causes malfunction and degradation of electronic equipment in civil or military applications, so the demand for absorbing materials is increasing.

Traditional absorbing materials include ferrite, barium titanate, metal powder, graphite, silicon carbide, conductive fibers, etc., which usually have the disadvantages of narrow absorption band, high density, high filling rate, easy oxidation, etc., which limit their practical application. application.

With the rapid development of science and technology, traditional absorbing materials can no longer meet the needs of the current sharp increase in frequency, and exploring new "wide, thin, light and strong" absorbing materials is the research direction in this field. Recent research results show that ingenious design of special structures with tunable electromagnetic parameters is a feasible strategy to improve microwave absorption performance.

The Chinese patent with publication number CN111629575A discloses a preparation method of MXene-based nanocomposite wave absorbing material, which is obtained by the following steps: mixing MXene prepared by etching method with metal salt and pre-processing, and then mixing the pre-treated mixed solution The MXene-based nanocomposite absorbing material is obtained after irradiation and post-processing. This patent improves the impedance matching of the composite material by introducing magnetic nanoparticles uniformly loaded on the surface of the MXene material. Therefore, the MXene-based nanocomposite absorber has a maximum reflection loss of 28dB and an effective absorption bandwidth of 2.65GHz.

The Chinese patent with publication number CN107645065A discloses a preparation method of onion carbon/MXene layered wave absorbing composite material: using titanium silicon carbon as raw material, after being corroded by different concentrations of hydrofluoric acid, washed with deionized water and dried to obtain MXene material; then, the prepared MXene material is uniformly dispersed in deionized water by ultrasonic dispersion to obtain a suspension of Mxene material; the onion carbon nanomaterial is uniformly dispersed in deionized water by ultrasonic dispersion to obtain onion carbon nanomaterials. Suspension of the material; the MXene material suspension solution and the onion carbon material suspension solution are alternately filtered to prepare the onion carbon/MXene layered wave absorbing composite material; the prepared onion carbon/MXene layered wave absorbing composite material It is lighter in weight, thinner in thickness and has better reflectivity in the microwave frequency range.

However, the relatively simple material structure design/combination of the absorbing composite materials disclosed in the above two patents has limited improvement in the absorbing performance of the material, and its absorption strength and effective bandwidth are both small. Based on this, it is urgent to design a composite nanostructured high-efficiency absorbing material with superior light-weight broadband absorbing properties.

SUMMARY OF THE INVENTION

The invention provides a zero-dimensional/one-dimensional/two-dimensional composite nano-structure type wave absorbing material, which has superior maximum reflectivity and absorption bandwidth.

A zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material, comprising two-dimensional MXene, zero-dimensional metal particles, and one-dimensional carbon nanotubes, wherein the zero-dimensional MXene is simultaneously loaded on the surface of the two-dimensional MXene. dimensional metal particles, and in situ growth of the one-dimensional carbon nanotubes.

In the material composed of zero-dimensional Co particles, one-dimensional carbon nanotubes (CNTs) and two-dimensional MXene in the present invention, the electrons at the hetero interface at the zero-dimensional/one-dimensional/two-dimensional material are due to the material The difference between the work functions can easily form the interface polarization consumption center of electromagnetic loss at the hetero interface, which greatly promotes the consumption of incident electromagnetic waves. In addition, since the presence of a large number of defects in CNTs and MXene can lead to dipolar polarization, and electronic transitions in the MXene/CNTs conductive network can cause conduction losses, the multi-scattering reflection and scattering between MXene sheets and CNTs also help to attenuate electromagnetic waves; The zero-dimensional metal particles can optimize the impedance matching of the wave absorber and provide magnetic loss, so that high frequency wave absorption characteristics can be achieved under the condition of low filling rate.

The general formula of the two-dimensional MXene is Mn ₊₁ X _n T, wherein M is 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, 3.

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

The present invention also provides a preparation method of a zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material, comprising:

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 mixed solution A is obtained by ultrasonication; an appropriate amount of organic ligands are dissolved in a certain organic solution and added to the solution. in solution A above. Finally, the mixed solution is stirred, left to stand, and dried to obtain MOF/MXene; and the MOF/MXene is carbonized at high temperature to obtain a zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material.

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

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

The organic ligands are 2-methylimidazole, 2-imidazole carboxaldehyde, 4-bromoimidazole, imidazole, benzimidazole, terephthalic acid, trimesic acid, and naphthalene tetraic anhydride.

The molar ratio of the metal salt to the organic ligand is 1:4-10. If the molar ratio is too high, the MOF particles will grow in different shapes. If the molar ratio is too low, the nucleation of MOF will be slow, which is not conducive to the electrostatic adsorption and recombination on the two-dimensional MXene.

The stirring time is 5-10min, and the standing time is 3-5h.

The solvothermal reaction parameters are as follows: the reaction temperature is 60-200° C., and the reaction time is 8-24 h.

The high-temperature carbonization process is as follows: in an Ar/H ₂ atmosphere, the heating rate is 2-10° C./min to 700-900° C., and the carbonization time is 2-8h.

Further, the volume ratio of Ar and H ₂ is 95%:5% vol/vol. , the purpose of adding H ₂ is to improve the reducibility of high temperature atmosphere, which is helpful to obtain Co particles and CNTs.

The invention also provides the application of the zero-dimensional/one-dimensional/two-dimensional composite nano-structure type wave absorbing material in the fields of military stealth and civil electromagnetic protection.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention utilizes the interface 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 dipolar polarization, The conduction loss, multi-scattering reflection and scattering between MXene sheets and CNTs that can be induced by electronic transitions in the conductive network of CNTs also contribute to the attenuation of 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, so as to further improve and optimize the high-frequency wave absorption properties of the material at a low filling rate. Through this structure, high-efficiency broadband absorption of electromagnetic waves can be achieved, and high-efficiency absorption can be achieved. The as-prepared zero-dimensional/one-dimensional/two-dimensional composite nanostructures show superior light-weight broadband absorption performance at 2-18 GHz, the maximum reflectivity can reach -50.5 dB, and the effective absorption bandwidth can reach 3.2 GHz.

(2) The preparation method provided by the present invention is simple and efficient, and is suitable for large-scale industrial production.

Description of drawings

FIG. 1 is the SEM and TEM schematic diagrams of Co@C/Ti ₂ C MXene with zero-dimensional/one-dimensional/two-dimensional structure prepared in Example 1, wherein FIG. 1(a) is the SEM image of Co@C/Ti ₂ C MXene , Figure 1(b) is the TEM image of Co@C/Ti ₂ C MXene;

Fig. 2 is the XRD characterization diagram of Co@C/Ti ₂ C MXene with zero-dimensional/one-dimensional/two-dimensional structure prepared in Example 1;

3 is a schematic diagram of the reflection loss curve of Co@C/Ti ₂ C MXene with zero-dimensional/one-dimensional/two-dimensional structure prepared in Example 1;

4 is a schematic diagram of the reflection loss curve of Ni@C/Nb ₂ C MXene with zero-dimensional/one-dimensional/two-dimensional structure prepared in Example 2;

5 is a schematic diagram of the reflection loss curve of Fe@C/V ₂ C MXene with zero-dimensional/one-dimensional/two-dimensional structure prepared in Example 3;

FIG. 6 is a schematic diagram of the reflection loss curve of Ti ₂ C MXene prepared in Comparative Example 1;

7 is a schematic diagram of the reflection loss curve of Co@C prepared in Comparative Example 2.

Detailed ways

The present invention will be further described below with reference to specific embodiments.

Example 1

A preparation method of high-efficiency microwave absorption composite material zero-dimensional/one-dimensional/two-dimensional Co@C/MXene, comprising the following steps:

(1) Preparation of Ti ₂ C MXene

At room temperature, weigh 2g of LiF powder and pour it into 40ml of HCl(AR), stir at room temperature for 40min at 350r/min, then pour _2g of MAX phase powder _Ti3AlC2 into the above solution, water bath at 35°C, and stir at 250r/min Stir for 24h. The resulting solution was washed with deionized water by repeated centrifugation until pH>6. Then, the obtained precipitate was diluted in a 500 ml beaker, and after sonicating for 3 hours, the supernatant was collected by centrifugation, and finally dried with a freeze dryer to obtain a single-layer Ti ₂ C MXene powder.

(2) Preparation of Co-MOF/Ti ₂ C MXene

Weigh 10 mg of the monolayer Ti ₂ C MXene prepared in the above (1) and dissolve it in 20 ml of methanol solution, add 1 mmol Co(NO ₃ ) ₂ ·6H ₂ O, and ultrasonically treat it for 1 h to obtain mixed solution A; at the same time, 8 mmol 2 -Methylimidazole was dissolved in 20ml methanol solution and stirred for 45min to obtain mixed solution B; under stirring conditions, A was poured into B, stirred for 2h, and then allowed to stand overnight, and then freeze-dried to obtain Co-MOF/MXene.

(3) Preparation of Co@C/Ti ₂ C MXene

The Co-MOF/Ti ₂ C MXene powder prepared in the above (2) was put into a tube furnace, and in the atmosphere of Ar/H ₂ , the temperature was raised to 800 ° C at a heating rate of 5 ° C/min and kept for 4 h. The powder was collected after cooling to obtain Co@C/Ti ₂ C MXene. SEM and TEM results show that (Figure 1a and b), the Co@C/Ti ₂ C MXene prepared in Example 1 has a remarkable 0D (metal particle)/1D (carbon nanotube)/2D (MXene material) structure nanocomposite structure; at the same time, the XRD results showed (Fig. 2) that the as-prepared Co@C/Ti ₂ C MXene had significant metal Co particles diffraction peaks, confirming the existence of metal particles.

Example 2

A preparation method of high-efficiency microwave absorption composite material 0D/1D/2D Ni@C/Nb ₂ C MXene, comprising the following steps:

(1) Preparation of Nb ₂ C MXene

It is basically the same as that in step (1) in Example 1, except that the Ti ₃ AlC ₂ MAX phase powder described in step (1) is replaced with Nb ₃ AlC ₂ MAX phase powder to prepare Nb ₂ CMXene.

(2) Preparation of Ni-MOF/Nb ₂ C MXene

Weigh 10 mg of the single-layer Nb ₂ C MXene prepared in the above (1) and dissolve it in 20 ml of methanol solution, add 1 mmol Ni(NO ₃ ) ₂ ·6H ₂ O, and ultrasonically treat it for 1 h to obtain mixed solution A; at the same time, 8 mmol 2 - Methylimidazole was dissolved in 20ml methanol solution and stirred for 45min to obtain mixed solution B; under stirring conditions, pour A into B, and after stirring for 10min, transfer the mixed solution to a 50ml reaction kettle and heat to 120 ℃ for 12h, centrifuge After washing, Ni-MOF/Nb ₂ CMXene was obtained by freeze-drying.

(3) Preparation of Ni@C/Nb ₂ C MXene

The Ni-MOF/MXene powder prepared in the above (2) was put into a tube furnace, and in the atmosphere of Ar/H ₂ , the temperature was raised to 800 °C at a heating rate of 5 °C/min for 4 h, and collected after natural cooling. powder to obtain Ni@C/MXene.

Example 3

A preparation method of high-efficiency microwave absorption composite material 0D/1D/2D Fe@C/V ₂ C MXene, comprising the following steps:

(1) Preparation of V ₂ C MXene

It is basically the same as that in step (1) in Example 1, except that the Ti ₃ AlC ₂ MAX phase powder described in step (1) is replaced with V ₃ AlC ₂ MAX phase powder to prepare V ₂ C MXene.

(2) Preparation of Fe-MOF/V ₂ C MXene

Weigh 10 mg of the monolayer V ₂ C MXene prepared in the above (1) and dissolve it in 20 ml of methanol solution, add 1 mmol Fe(NO ₃ ) ₂ ·6H ₂ O, and ultrasonically treat it for 1 h to obtain mixed solution A; at the same time, 8 mmol 2 - Methylimidazole was dissolved in 20ml methanol solution and stirred for 45min to obtain mixed solution B; under stirring conditions, pour A into B, after stirring for 10min, transfer the mixed solution to a 50ml reaction kettle, heat to 80°C for 12h, centrifuge After washing, Fe-MOF/V ₂ CMXene was obtained by freeze-drying.

(3) Preparation of Fe@C/V ₂ C MXene

The Fe-MOF/V ₂ C MXene powder prepared in the above (2) was put into a tube furnace, and in the atmosphere of Ar/H ₂ , the temperature was raised to 800 ° C at a heating rate of 5 ° C/min and kept for 4 h. The powder was collected after cooling to obtain Fe@C/V ₂ C MXene.

Comparative Example 1

The preparation steps are the same as step (1) in Example 1, the difference is that only Ti ₂ CMXene is prepared, excluding the subsequent MOF growth and catalytic cracking steps.

Comparative Example 2

The preparation steps are basically the same as those in Example 1, the only difference is that Ti ₂ C MXene is not added, and the preparation process is included and named Co@C. The specific preparation steps are as follows:

(1) Preparation of Co-MOF

Add 1 mmol Co(NO ₃ ) ₂ ·6H ₂ O to 20 ml of methanol solution, and ultrasonically treat for 1 h to obtain 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 mixed solution B; Condition, pour A into B, stir for 10min, transfer the mixed solution to a 50ml reaction kettle and heat to 120℃ for 12h, after centrifugal washing, obtain Ni-MOF by freeze-drying.

(2) Preparation of Co@C

The Co-MOF powder prepared in the _second step was put into a tube furnace, and in the atmosphere of Ar/H, the temperature was raised to 800 °C at a heating rate of 5 °C/min for 4 h, and the powder was collected after natural cooling to obtain Co. @C.

Application example

The above zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material is mixed into silica gel according to a certain mass ratio, and after uniform stirring, the film is formed by casting and scraping. The film is prepared into an electromagnetic wave absorbing patch with a certain thickness. Finally, the obtained wave absorbing patch is cut into a customized size and shape, and attached to the target electromagnetic source, so as to achieve the purpose of electromagnetic protection. In terms of civil use, taking the sub-6G communication mobile phone 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 wave absorbing patch prepared above is attached to the electromagnetic path in the mobile phone. position, which can effectively reduce the crosstalk of internal high-frequency signals, achieve the purpose of electromagnetic compatibility of the working frequency band and improve the quality of communication. In terms of military use, the working frequency of the current military fire control and target tracking radar is mostly in the X-band (the frequency range is 8-12GHz, and its wavelength is below 3 cm). Effectively carry out radar stealth and improve radar battlefield survivability.

Performance characterization:

The wave-absorbing materials prepared in the above-mentioned Examples 1-3 and Comparative Examples 1-2 were uniformly mixed with molten paraffin in a mass ratio of 1:1 (that is, the absorbent content was 50%), and were pressed in a special mold to have an inner diameter of 3.0mm, 7.0mm outer diameter, 2.0mm thick standard coaxial ring specimen. Using a vector network analyzer (VNA; model: Agilent N5234A), the coaxial method was used to test the magnetoelectric properties of the electromagnetic waves of each sample in the range of 2-18 GHz.

The electromagnetic wave absorption performance of the sample prepared by using the Co@C/Ti ₂ C MXene wave absorbing material described in Example 1 is shown in FIG. 3 . When the matching thickness is 2.0mm, its effective bandwidth is 3.2GHz in the 2-18GHz frequency band, and the maximum reflectivity is -50dB;

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

The electromagnetic wave absorption performance of the sample prepared by using the Fe@C/V ₂ C MXene wave absorbing material described in Example 3 is shown in FIG. 5 . When the matching thickness is 2.0mm, the effective bandwidth is 3.2GHz in the 2-18GHz frequency band, and the maximum reflectivity is -43dB.

The electromagnetic wave absorption performance of the sample prepared by using the Ti ₂ C MXene wave absorbing material described in Comparative Example 1 is shown in FIG. 6 . When the matching thickness is 2.0mm, its effective bandwidth is 0GHz in the 2-18GHz frequency band, and the maximum reflectivity is -7.3dB.

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

The above-mentioned embodiments only represent the embodiments of the present invention, and should not be construed as limiting the scope of the present invention. It should be pointed out that all equivalent changes or modifications made according to the present invention should be included within the protection scope of the present invention.

Claims (10)

1. A composite nanostructured wave absorbing material with zero-dimensional/one-dimensional/two-dimensional structure, characterized in that it comprises two-dimensional MXene, zero-dimensional metal particles, and one-dimensional carbon nanotubes, wherein, in the two-dimensional MXene The zero-dimensional metal particles are supported on the surface, and the one-dimensional carbon nanotubes are grown in situ. 2. The absorbing material with zero-dimensional/one-dimensional/two-dimensional composite nanostructures according to claim 1, wherein the general formula of the two-dimensional MXene is _{Mn +} 1XnT, wherein, M is transition metal Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta or W; X is carbon and/or nitrogen; T is O, F or OH functional group; wherein, n is 1, 2 , 3. 3 . The absorbing material with a zero-dimensional/one-dimensional/two-dimensional composite nanostructure according to claim 1 , wherein the zero-dimensional metal is Fe, Co or Ni. 4 . 4. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructure type wave absorbing material according to any one of claims 1-3, characterized in that, comprising: 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 sonicating, and after adding an organic ligand to the mixed solution, stirring, static Set and dry to obtain MOF/MXene; carbonize the MOF/MXene at high temperature to obtain a zero-dimensional/one-dimensional/two-dimensional composite nano-structured wave absorbing material. 5. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to claim 4, wherein the organic solution is a monohydric alcohol, a dihydric alcohol or a polyhydric alcohol and the same. mixed solvent. 6. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to claim 4, wherein the metal salt is nitrate, sulfate, carbonate, vinegar salts or chlorides. 7. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to claim 4, wherein the organic ligand is 2-methylimidazole, 2-imidazole carboxaldehyde , 4-bromoimidazole, imidazole, benzimidazole, terephthalic acid, trimesic acid or naphthalene tetracarboxylic anhydride. 8. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to claim 4, wherein the molar ratio of the metal salt to the organic ligand is 1:4- 10. 9. The preparation method of zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to claim 4, wherein the high _- temperature carbonization process is: in an Ar/H atmosphere, the temperature rises The heating rate is (2-10)/min to 700-900°C, and the carbonization time is 2-8h. 10. The application of the zero-dimensional/one-dimensional/two-dimensional composite nanostructured wave absorbing material according to any one of claims 1-3 in the fields of military stealth and civil electromagnetic protection.

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