阅读说明：本技术 一种纳米复合材料及其制备方法和用途 (Nano composite material and preparation method and application thereof ) 是由 陆伟 向震 熊娟 邓柏闻 刘志成 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种纳米复合材料及其制备方法和用途,其中,制备方法至少包括如下步骤：将铁盐和芳香多元羧酸通过反应介质负载到氧化石墨烯表面。本发明能获得成分可调、结构可控和高性能的吸波材料。(The invention discloses a nano composite material and a preparation method and application thereof, wherein the preparation method at least comprises the following steps: and loading iron salt and aromatic polycarboxylic acid on the surface of the graphene oxide through a reaction medium. The invention can obtain the wave-absorbing material with adjustable components, controllable structure and high performance.)

1. A method for preparing a nanocomposite, characterized by comprising at least the steps of:

providing a reaction medium;

loading iron salt and aromatic polycarboxylic acid on the surface of graphene oxide through the reaction medium, and heating to obtain an intermediate;

and carrying out heat treatment on the intermediate under the inert gas atmosphere to obtain the nano composite material.

2. The method of claim 1, wherein the reaction medium comprises N, N-dimethylformamide or methanol.

3. The process according to claim 1, characterized in that the molar ratio between said iron salt, said aromatic polycarboxylic acid and said reaction medium is 1: 1: (65-1040).

4. The method according to claim 1, characterized in that it comprises the dropwise addition of a sodium hydroxide solution to said reaction medium, the molar ratio between sodium hydroxide and said iron salt in said sodium hydroxide solution being 1: (1-3).

5. The method according to claim 1, wherein the state of the graphene oxide is a colloidal suspension.

6. The method according to claim 1, wherein the aromatic polycarboxylic acid is one or more selected from the group consisting of trimesic acid, terephthalic acid and p-toluic acid.

7. The method of claim 1, wherein the heating step comprises microwave heating.

8. The method as set forth in claim 1, wherein the heating temperature in the heat treatment step is 500-700 ℃.

9. A nanocomposite obtained by the production method as claimed in any one of claims 1 to 8.

10. Use of the nanocomposite material produced by the production method according to any one of claims 1 to 8 in the field of electromagnetic wave absorbing materials.

Technical Field

The invention belongs to the field of functional materials, and particularly relates to a nano composite material, and a preparation method and application thereof.

Background

With the rapid development of scientific technology and electronic industry, various digital and high-frequency electronic and electrical equipment radiate a large amount of electromagnetic waves with different frequencies to the space during working, thereby causing electromagnetic radiation pollution. In order to solve the problem of electromagnetic pollution and realize the invisibility of the battlefield of equipment, the wave-absorbing material is produced at the right moment. An ideal electromagnetic wave absorbing material must meet the requirements of strong absorption, wide bandwidth, light density and thin matching thickness. At present, the microwave absorption performance of conventional electromagnetic wave absorbing materials has been improved, but the conventional magnetic media have strong microwave absorption capacity, and the high density, large thickness and narrow absorption bandwidth limit their widespread use as microwave absorbers. Although the traditional electrically-lossy carbon-based wave-absorbing materials have realized wide bandwidth, light weight and high stability, impedance mismatch between carbon and air causes reflection of a large amount of incident electromagnetic waves, limiting their wide application. Therefore, it is very difficult to achieve high performance electromagnetic wave absorption for a single magnetic medium and dielectric medium. The method for preparing the wave-absorbing material with adjustable components, controllable structure and high performance by a simple and controllable preparation method still has certain difficulty.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention aims to provide a nanocomposite material, a preparation method and a use thereof, which overcome the technical defects that the wave-absorbing material in the prior art is difficult to meet the requirements of strong absorption capacity, wide absorption band, light weight, thin matching thickness, etc., and is difficult to obtain a wave-absorbing material with adjustable components, controllable structure and high performance.

In order to achieve the above objects or other objects, the present invention provides a method for preparing a nanocomposite, comprising at least the steps of:

providing a reaction medium;

loading iron salt and aromatic polycarboxylic acid on the surface of graphene oxide through the reaction medium, and heating to obtain an intermediate;

and carrying out heat treatment on the intermediate under the inert gas atmosphere to obtain the nano composite material.

In one embodiment, the reaction medium comprises one of N, N-dimethylformamide or methanol.

In one embodiment, the molar ratio between the iron salt, the aromatic polycarboxylic acid and the reaction medium is 1: 1: (65-1040).

In one embodiment, the preparation method comprises adding dropwise a sodium hydroxide solution to the reaction medium, wherein the molar ratio between sodium hydroxide in the sodium hydroxide solution and the iron salt is 1: (1-3).

In an embodiment, the state of the graphene oxide is a colloidal suspension.

In one embodiment, the graphene oxide has a microscopic morphology of a flake shape and a size of a micron number scale.

In one embodiment, the aromatic polycarboxylic acid is one or more of trimesic acid, terephthalic acid and p-toluic acid in combination.

In one embodiment, the heating step comprises microwave heating. The temperature in the microwave heating step is 100-150 ℃. The microwave power in the microwave heating step is 3-5 kw. The heating time in the microwave heating step is 2 minutes to 60 minutes.

In one embodiment, the heating temperature in the heat treatment step is 500-700 ℃.

In one embodiment, the heating time in the heat treatment step is 60 to 120 minutes.

In one embodiment, the temperature increase rate in the heat treatment step is 5 to 20 ℃/min.

The invention also aims to provide a nano composite material prepared by the preparation method.

The invention also aims to provide the application of the nano composite material prepared by the preparation method in the field of electromagnetic wave absorption materials.

The invention decomposes the precursor containing iron into Fe by a microwave-assisted in-situ synthesis method₃O₄A composite of nanoparticles (30nm) and carbon or α -Fe nanoparticles (60nm) and a crystallized carbon layer (4nm) on the surface, and uniformly dispersed on the surface of graphene oxide. The controllable broadband and strong-absorption nano electromagnetic composite material can be prepared by simple in-situ chemical synthesis and thermal decomposition processes, and the process parameters can effectively regulate and control phase components and microstructures of the nano electromagnetic composite material and finally regulate and control the wave-absorbing performance of the nano electromagnetic composite material. The preparation process of the invention is controllable, stable, simple and feasible, thereby greatly promoting the industrial production and the preparation of the inventionHas important significance in the wide application and development of nano electromagnetic composite materials.

Drawings

FIG. 1: the flow diagram of the preparation method of the nano composite material in one embodiment of the invention;

FIG. 2: XRD patterns of nanocomposite a, nanocomposite B and nanocomposite C of the invention;

FIG. 3: SEM image of the nanocomposite material A in one embodiment of the present invention;

FIG. 4: SEM image of the nanocomposite material B in one embodiment of the present invention;

FIG. 5: SEM image of the nanocomposite C according to an embodiment of the present invention;

FIG. 6: magnetic property diagrams of nanocomposite A, nanocomposite B and nanocomposite C of the invention;

FIG. 7: specific surface area maps of nanocomposite a, nanocomposite B and nanocomposite C of the invention;

FIG. 8: the change curve of the reflection loss of the nano composite material A along with the frequency;

FIG. 9: the change curve of the reflection loss of the nanocomposite material B along with the frequency;

FIG. 10: the change curve of the reflection loss with frequency of the nanocomposite C of the invention.

Detailed Description

The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. It is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs and the description of the present invention, and any methods, apparatuses, and materials similar or equivalent to those described in the examples of the present invention may be used to practice the present invention.

Referring to fig. 1, the present invention provides a method for preparing a nanocomposite, which at least comprises the following steps:

s1, providing a reaction medium;

s2, loading iron salt and aromatic polycarboxylic acid on the surface of graphene oxide through the reaction medium, and heating to obtain an intermediate;

s3, carrying out heat treatment on the intermediate under the inert gas atmosphere to obtain the nanocomposite.

Specifically, in the step S1, the reaction medium includes one of N, N-dimethylformamide or methanol.

Specifically, in the step S2, the iron salt includes ferric chloride, ferric sulfate, and the like. The graphene oxide is a colloidal suspension prepared by using graphite powder through a Hummers oxidation method, and the microscopic form of the graphene oxide is flaky, and the size of the graphene oxide is in the micron quantity level. The aromatic polycarboxylic acid is one or a combination of more of trimesic acid, terephthalic acid and p-toluic acid. Before microwave heating treatment, dropwise adding a sodium hydroxide solution into the reaction medium at a constant speed, wherein the molar ratio of sodium hydroxide in the sodium hydroxide solution to the iron salt is 1: (1-3), dropwise adding the sodium hydroxide solution, uniformly stirring, exhausting to eliminate the influence of air on the reaction, and performing heating treatment such as microwave heating after exhausting is finished, wherein the conditions of the microwave heating comprise: the microwave power is 3-5 kw, the temperature is 100-150 ℃, and the heating time is 2-60 minutes. The molar ratio between the iron salt, the aromatic polycarboxylic acid and the reaction medium is 1: 1: (65-1040). The graphene oxide is firstly dissolved in a reaction medium such as N, N-dimethylformamide, and the concentration is 1 mg/ml-10 mg/ml.

Specifically, in the step S3, the heat treatment temperature is 500-700 ℃, and the heat preservation time is 60-120 minutes. The heating rate during the heat treatment is 5-20 ℃/min.

In one embodiment, 10mg to 40mg of graphene oxide is dissolved in 10ml to 40ml of N, N-dimethylformamide, and the solution is magnetically stirred for 12 to 24 hours at 25 ℃ to prepare a graphene oxide N, N-dimethylformamide solution; respectively adding 2.1624g-2.5 g of ferric chloride hexahydrate and 1.3290g-1.5g of terephthalic acid into the prepared graphene oxide N, N-dimethylformamide solution, and magnetically stirring for 2-4 hours at 25 ℃; dropwise adding sodium hydroxide solution with the volume of 4ml-5ml and the concentration of 1mol/L-2mol/L at a constant speed, and magnetically stirring for 2-4 hours at 25 ℃ to obtain uniform solution; placing the obtained uniform solution in a container such as a three-neck flask, exhausting gas for 1-2 hours, heating such as microwave heating, centrifuging the prepared sample, respectively washing the obtained precipitate with N, N-dimethylformamide and deionized water for three times, then placing the precipitate in a 50-60 ℃ oven, and drying for 12-24 hours to obtain the metal organic framework-graphene oxide material, namely the Fe-MOFs/GO composite material, wherein the microwave reaction parameters comprise: the microwave power is 3-5 kw, the temperature is 100-150 ℃, and the heating time is 2-60 minutes; carrying out heat treatment on the prepared Fe-MOFs/GO composite material in an argon atmosphere, ventilating for 30-40 minutes, wherein the heating rate is as follows: heating to 500 ℃ at the temperature of 5 ℃/min, preserving the heat for 30-60 min, and then cooling to room temperature along with the furnace to obtain the nano composite material A.

FIG. 2 shows the X-ray diffraction pattern of the nanocomposite material A obtained in this example (Cu-Ka as an irradiation source)X-ray diffraction) of (b), as seen from the curve S500 in fig. 2, the composite materialThe material is mainly ferroferric oxide Fe₃O₄Phase, obtained by crystal size calculation (calculated by WPF refinement module using Jade software), the crystal size produced in this example was 24 nm. Referring to fig. 3, it is seen from fig. 3 that the phase components of the product in this embodiment are ferroferric oxide, carbon and reduced graphene oxide, which is denoted as Fe₃O₄@ C @ rGO, the metal organic framework Fe-MOFs precursor is decomposed into Fe₃O₄The composite material comprises nano particles (the particle size is 30nm) and carbon, and the composite material is uniformly dispersed on the surface of the reduced graphene oxide.

In another embodiment, 100mg to 200mg of graphene oxide is dissolved in 10ml to 40ml of N, N-dimethylformamide, and magnetically stirred at 25 ℃ for 12 to 24 hours to prepare a graphene oxide N, N-dimethylformamide solution; 0.5406g to 1.0g of ferric chloride hexahydrate and 0.3323g to 0.5g of terephthalic acid are respectively added into the prepared graphene oxide N, N-dimethylformamide solution, and magnetic stirring is carried out for 2 to 4 hours at the temperature of 25 ℃; dropwise adding 1-2 ml of 1-2 mol/L sodium hydroxide solution at constant speed, and magnetically stirring at 25 deg.C for 2-4 hr to obtain uniform solution; placing the uniform solution in a three-neck flask, exhausting gas for 1-2 hours, heating, such as microwave heating, centrifuging the prepared sample, respectively washing the obtained precipitate with N, N-dimethylformamide and deionized water for three times, then placing the precipitate in an oven at 50-60 ℃, and drying for 12-24 hours to obtain the Fe-MOFs/GO nano composite material, wherein the microwave reaction parameters are as follows: the microwave power is 3-5 kw, the temperature is 100-150 ℃, and the heating time is 2-60 minutes; carrying out heat treatment on the prepared Fe-MOFs/GO nano composite material in an argon atmosphere, ventilating for 30 minutes, and heating at a temperature rise rate: heating to 600 ℃ at the temperature of 10 ℃/min, preserving the heat for 30-60 min, and then cooling to room temperature along with the furnace to obtain the nano composite material B.

FIG. 2 shows the X-ray diffraction pattern of the nanocomposite material B obtained in this example (Cu-Ka as an irradiation source)X-ray diffraction of (a),as seen from the S600 curve in FIG. 2, the composite material is mainly Fe₃O₄The phase, which also contains a carbon crystal phase, produced in this example had a crystal size of 42nm, calculated from the crystal size. The scanning electron micrograph of the product obtained in this example is shown in fig. 4, and it is seen from fig. 4 that the phase component of the product in this example is Fe₃O₄@ C @ rGO, Fe-MOFs precursors are decomposed to Fe₃O₄The composite material comprises nanoparticles (40nm) and carbon, and the composite material is uniformly dispersed on the surface of the reduced graphene oxide.

In another embodiment, 300mg to 400mg of graphene oxide is dissolved in 10ml to 40ml of N, N-dimethylformamide, and magnetically stirred at 25 ℃ for 12 to 24 hours to prepare a graphene oxide N, N-dimethylformamide solution; respectively adding 0.1352g to 0.5g of ferric chloride hexahydrate and 0.0831g to 0.1g of terephthalic acid into the prepared graphene oxide N, N-dimethylformamide solution, and magnetically stirring for 2 to 4 hours at the temperature of 25 ℃; dropwise adding NaOH solution with the volume of 0.25-0.5 ml and the concentration of 1-2 mol/L at constant speed, and magnetically stirring for 2-4 hours at 25 ℃ to obtain uniform solution; placing the obtained uniform solution in a three-neck flask, exhausting gas for 1 hour, heating for example by microwave heating, centrifuging the prepared sample, respectively washing the obtained precipitate with N, N-dimethylformamide and deionized water for three times, then placing the precipitate in a 60 ℃ oven, and drying for 24 hours to obtain the Fe-MOFs/GO nano composite material, wherein the microwave reaction parameters are as follows: the microwave power is 3-5 kw, the temperature is 100-150 ℃, and the heating time is 2-60 minutes; carrying out heat treatment on the Fe-MOFs/GO nano composite material in an argon atmosphere, ventilating for 30 minutes, and heating at a temperature rise rate: heating to 700 ℃ at the temperature of 20 ℃/min, preserving the heat for 30-60 min, and then cooling to room temperature along with the furnace to obtain the nanocomposite C.

FIG. 2 shows the X-ray diffraction pattern of the nanocomposite material C obtained in this example (Cu-Ka as an irradiation source)X-ray diffraction of (b), as can be seen from the S700 curve in fig. 2, the composite material is mainly an alpha-Fe phase and a carbon crystal phase,the crystal sizes of the products obtained in this example were 64nm, respectively, by calculation of the crystal sizes. The scanning electron microscope image of the product obtained in this example is shown in fig. 5, and as seen from fig. 5, in this example, the Fe-MOFs phase changes into α -Fe nanoparticles (60nm) and a crystallized carbon layer (4nm) on the surface, the Fe @ C complex is uniformly dispersed on the surface of the reduced graphene oxide, and the phase component is Fe @ C @ rGO.

Performance testing

1. The magnetic properties of the product were obtained by a physical property measurement system, and the results of the test were hysteresis loops in fig. 6.

2. The nitrogen adsorption-release curves of the samples were recorded by using a Quad-rasorb-SI apparatus, and the specific surface areas of the samples were measured by the BET method, respectively, and the results are shown in FIG. 7, in which S500 represents nanocomposite A, S600 represents nanocomposite B, S700 represents nanocomposite C, and the specific surface areas of nanocomposite A, nanocomposite B and nanocomposite C were 275m in this order²/g、252m²/g、135m²(ii)/g; the specific surface area of the composite material gradually decreases with the increase of the thermal decomposition temperature. The method is mainly caused by continuous collapse of Fe-MOFs nano particles in the thermal decomposition process and continuous growth of magnetic nano particles, but the prepared nano electromagnetic composite material has porosity and higher specific surface area, and the microwave absorption performance of the composite material is favorably improved.

3. Respectively taking the nano composite material A, the nano composite material B and the nano composite material C, uniformly dispersing the nano composite material A, the nano composite material B and the nano composite material C into paraffin so that the composite material accounts for 30 percent of the total mass of the composite material and the paraffin, pressing into ring pieces (0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm and 5mm) with the outer diameter of 7.0mm, the inner diameter of 3.04mm and different thicknesses, measuring the complex dielectric constant and the electromagnetic parameter of the complex permeability of the electromagnetic parameter by using a coaxial line method by using an Agilent N52 5224A vector network analyzer, wherein the test frequency range is 2-18GHz, and the change curve of the obtained reflection loss along with the frequency is shown in fig. 8-10.

As can be seen from FIG. 8, the thickness range of the nanocomposite A obtained in one embodiment is 2-5 mm, and the wave-absorbing bandwidth (RL) of the nanocomposite A is wide<-10dB) of 4.0 to 18.0GHz, the minimum wave-absorbing bandwidth RL when the frequency is 7.5GHz and the thickness of the sample is 2.5mm_minIs-38.5 dB; as can be seen from FIG. 9, the thickness range of the nanocomposite B obtained in one embodiment is 1.5-5 mm, and the wave-absorbing bandwidth (RL) of the nanocomposite B is wide<-10dB) of 3.8 to 18.0GHz, and the minimum wave-absorbing bandwidth RL when the frequency is 13.2GHz and the thickness of the sample is 2.0mm_minIs-72.6 dB. As can be seen from FIG. 10, the thickness range of the nanocomposite C obtained in one embodiment is 1.5-5 mm, and the wave-absorbing bandwidth (RL) of the nanocomposite C is wide<-10dB) of 3.0 to 17.0GHz, and the minimum wave-absorbing bandwidth RL when the frequency is 14.5GHz and the thickness of the sample is 1.5mm_minIs-50.8 dB. Therefore, with the improvement of the thermal decomposition temperature, the reflection intensity of the composite material is firstly reduced and then increased (-38.3 dB-72.6 dB-50.8 dB), the effective absorption frequency gradually moves to high frequency (7.5 GHz-13.2 GHz-14.5 GHz), and the matching thickness is gradually reduced (2.5 mm-2.0 mm-1.5 mm), namely, the reflection intensity, the effective frequency width and the matching thickness of the electromagnetic composite material can be regulated and controlled by controlling the thermal decomposition process parameters. Therefore, the electromagnetic composite material prepared by the invention has excellent wave-absorbing performance of wide-frequency strong absorption. Nano magnetic particles (Fe)₃O₄The synergistic effect among the alpha-Fe), the nano porous carbon and the reduced graphene oxide promotes the excellent wave-absorbing performance of the electromagnetic composite material through the combined action of electric loss and magnetic loss.

The results of some examples of the present invention are shown in Table 1, and are illustrated as examples:

TABLE 1 Performance test data sheet

In conclusion, the controllable broadband and strong-absorption nano electromagnetic composite material can be prepared by simple in-situ chemical synthesis and thermal decomposition processes. The technological parameters of the invention can effectively regulate and control the phase composition and microstructure of the nano electromagnetic composite material, and finally regulate and control the wave absorbing performance of the nano electromagnetic composite material. The preparation process of the invention is controllable, stable, simple and feasible, thereby greatly promoting the industrial production and being used for the nano electromagnetic recoveryThe wide application and development of composite materials have important significance. In the present invention are nano-magnetic particles (Fe)₃O₄alpha-Fe), the nano porous carbon and the reduced graphene oxide achieve excellent wave-absorbing performance under the synergistic effect of the alpha-Fe), the nano porous carbon and the reduced graphene oxide.

The invention also aims to provide the application of the nano composite material prepared by the preparation method in the field of electromagnetic wave absorption materials. The wave absorbing mechanism of the nano composite material is as follows: the electromagnetic wave is converted into heat energy or other forms of energy to be dissipated, or the electromagnetic wave disappears due to interference, so that the incident electromagnetic wave is absorbed and attenuated. The nano composite material provided by the invention is applied to the field of electromagnetic wave absorption materials and can meet the wave absorption performance requirements of strong absorption, wide bandwidth, light density and thin matching thickness.

Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.