CN113200533B - Preparation method of high-performance graphene/bismuth telluride microwave absorption composite material - Google Patents

Preparation method of high-performance graphene/bismuth telluride microwave absorption composite material Download PDF

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CN113200533B
CN113200533B CN202110492821.1A CN202110492821A CN113200533B CN 113200533 B CN113200533 B CN 113200533B CN 202110492821 A CN202110492821 A CN 202110492821A CN 113200533 B CN113200533 B CN 113200533B
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bismuth telluride
graphene
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graphene oxide
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CN113200533A (en
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黄毅
刁江林
夏伦
蔡志灏
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Nankai University
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    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
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Abstract

The invention relates to a preparation method of a high-performance graphene/bismuth telluride microwave absorption composite material. Uniformly mixing the bismuth telluride ethanol solution and the graphene oxide ethanol solution to form a colloidal solution; forming three-dimensional graphene oxide/bismuth telluride gel through solvothermal reaction, and replacing the whole system into a water system; freezing the intermediate material filled with water at low temperature to solid state, freeze drying to remove ice, and reducing at high temperature under argon atmosphere. According to the invention, the dielectric constant and the refractive index of the material are reduced by constructing a porous structure, the surface reflection of incident electromagnetic waves is reduced, most of the electromagnetic waves can be incident into the material, and the synergistic effect between the graphene material and the loaded bismuth telluride is utilized to realize the synergistic response to the electromagnetic waves, so that the absorption attenuation to the electromagnetic waves is improved, and finally the high absorption intensity and the broadband absorption to the microwaves are realized. The invention shows high application value in civil anti-electromagnetic radiation interference and military fields.

Description

Preparation method of high-performance graphene/bismuth telluride microwave absorption composite material
Technical Field
The invention belongs to the technical field of electromagnetic wave stealth, and particularly relates to a preparation method of a high-performance graphene/bismuth telluride microwave absorbing composite material, in particular to a graphene/bismuth telluride microwave absorbing composite material with high absorbing performance and ultra-wide-frequency absorbing capacity and a preparation method thereof.
Background
With the vigorous development of information transmission and detection technology, electromagnetic waves are widely applied to the fields of communication, remote control, radar and the like, and in the near future, the use of broadband and high-power electromagnetic waves causes serious electromagnetic wave pollution, threatens information security and endangers homeland security. Therefore, there is an urgent need to develop high-performance electromagnetic wave absorbing materials for civil and military stealth devices. In recent years, researchers have endeavored to develop highly efficient microwave absorbing materials with high absorptivity and wide acceptable absorption bandwidth (reflection loss ≦ -10 dB). Electromagnetic losses and interface impedance matching are the two most important factors affecting electromagnetic wave absorption. Most fillers are added randomly to the matrix, the desired properties are not well achieved with a random distribution of fillers, and the properties of the absorbent material are limited. The integration of a low reflective surface structure and a high loss frame structure has proven to be a very efficient way of achieving high performance microwave absorption. Studies have demonstrated that the broadband absorption of graphene foams with three-dimensional interconnected networks is different from the narrow absorption bandwidth using graphene as a filler material. Although the three-dimensional graphene can effectively broaden the absorption bandwidth, strong absorption cannot be achieved. Later, a series of three-dimensional graphene composites were developedMaterials, e.g. Fe3O4A/graphene material, a MWCNT/graphene material and an MXene/graphene composite. The three-dimensional graphene composite material is proved to be a very effective microwave absorption material, so that the absorption range is expanded, and the absorption strength is increased. However, the microwave absorption intensity of the three-dimensional graphene composite material is still insufficient, mostly less than 50dB (absolute reflection loss value)<50 dB). It is well known that an absorbing material can exhibit excellent electromagnetic wave absorbing properties when electromagnetic waves are transmitted into the material as much as possible and can be converted into other forms of energy as quickly and efficiently as possible.
Bismuth telluride (Bi)2Te3) Widely used as a thermoelectric material operating at room temperature, which is an excellent room temperature thermoelectric material, has excellent electrical conductivity, and can reach about 150S/cm. In addition, the synthesized bismuth telluride is a two-dimensional material, can provide a plurality of sites beneficial to the attenuation of electromagnetic waves, can effectively convert heat into electric energy, thereby promoting the attenuation of the electromagnetic waves, and has important significance for exploring a novel thermoelectric composite wave-absorbing material with high performance in absorbing waves and hiding.
Chinese patent CN106637489A discloses a polymer skin-core composite fiber with thermoelectric effect, a preparation method and application thereof, which is composed of a polymer skin layer and a thermoelectric master batch material core layer; the thermoelectric master batch material core layer is composed of three components of graphene, bismuth telluride and resin. The preparation method of the thermoelectric master batch material comprises the steps of mixing graphene and bismuth telluride, carrying out electromagnetic crushing under the protection of inert gas, and then carrying out ball milling. The fiber material can be made into thermoelectric cooling devices to be arranged in fabrics and clothes, and the temperature is adjustable, so that the temperature is comfortable and adjustable.
CN110473935A discloses a preparation method of a bismuth telluride-graphene heterojunction, which is to transfer graphene and bismuth telluride nanosheets grown by a chemical vapor deposition method to a silicon dioxide insulating layer in sequence to obtain a terahertz wave detector based on the bismuth telluride-graphene heterojunction.
CN111171787A discloses a BFO/RGO composite material with centimeter wave absorption and millimeter wave attenuation performances and a preparation method thereof. The preparation method comprises the steps of adding bismuth ferrite and hexadecyl trimethyl ammonium bromide into a graphene oxide aqueous solution together, and carrying out hydrothermal reaction on the obtained suspension, wherein the maximum reflection loss value of the composite material is-32.3 dB, and the effective bandwidth is 4.1 GHz. The composite material can be used in military stealth.
In view of the fact that the microwave absorption strength of the materials is still insufficient, a novel three-dimensional thermoelectric absorption material is constructed, wherein an electromagnetic wave-heat energy-electric energy rapid consumption electromagnetic wave mode is adopted to realize high-performance wave absorption, and the bismuth telluride thermoelectric material serving as the wave absorption material is not reported yet and belongs to a novel wave absorption material.
Disclosure of Invention
The invention aims to provide a preparation method of a high-performance graphene/bismuth telluride microwave absorption composite material, which can realize high wave-absorbing strength and broadband absorption. The composite material obtained by the invention has a highly porous structure, so that the dielectric constant and the refractive index of the material are reduced, the surface reflection of incident electromagnetic waves is reduced, and most of the electromagnetic waves can be incident into the material. In addition, the synergistic effect between the graphene material and the loaded bismuth telluride is utilized to realize the synergistic response to the electromagnetic waves, so that the absorption attenuation of the whole material system to the electromagnetic waves is improved, and the high absorption strength and the broadband absorption are both considered finally. The wave-absorbing material with high absorption strength and wide frequency band of the invention can show extremely high application value in the civil and military fields.
The invention provides a preparation method of a high-performance graphene/bismuth telluride microwave absorption composite material, which comprises the following steps: uniformly mixing the bismuth telluride ethanol solution and the graphene oxide ethanol solution to form a colloidal solution; then forming three-dimensional graphene oxide/bismuth telluride gel through solvothermal reaction, and replacing the whole ethanol system with a water system; freezing the intermediate material filled with water to be solid at low temperature, removing ice through freeze drying, and finally reducing at high temperature in an argon atmosphere to obtain the graphene/bismuth telluride wave-absorbing material; the method comprises the following specific steps:
1) respectively adding bismuth telluride powder and graphene oxide powder into ethanol, violently stirring to obtain a bismuth telluride ethanol solution, mixing with a graphene oxide ethanol solution, and performing ultrasonic treatment and stirring uniformly to form a stable colloidal solution.
2) Transferring the obtained colloidal solution into a polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and reacting for 6-36h at the temperature of 100-240 ℃. And naturally cooling to room temperature, taking out the graphene oxide/bismuth telluride composite material filled with ethanol, and completely replacing the graphene oxide/bismuth telluride composite material into a water system.
3) The above system was gradually frozen in liquid nitrogen to a solid state. The freezing temperature is-196 ℃ to-10 ℃;
4) and (3) freeze-drying the obtained completely frozen graphene oxide/bismuth telluride and ice solid compound at the temperature of-20-15 ℃ for 48-180h to obtain a dried graphene oxide/bismuth telluride composite material.
5) In argon gas, gradually heating, and carrying out heat treatment reduction on the obtained graphene oxide/bismuth telluride composite material at the temperature of 200-600 ℃ for 0.5-6h to finally obtain the graphene/bismuth telluride wave-absorbing material.
6) And carrying out microwave frequency band 2-18GHz reflectivity test on the obtained graphene/bismuth telluride wave-absorbing material.
The mass ratio of the graphene to the bismuth telluride is 2.5-10: 0.5-8.
Preferably, the reaction temperature in the step 2) is 240 ℃ and the reaction time is 6 h.
Preferably, the freezing temperature of step 3) is-50 ℃.
Preferably, the freeze-drying time in the step 4) is 136h, and the freeze-drying temperature is-8 ℃.
Preferably, the reduction temperature of the heat treatment in the step 5) is 210 ℃; the thermal reduction time is 1.5h, and the mass ratio of the graphene to the bismuth telluride is 9: 1.
preferably, the thermal reduction temperature in the step 5) is 310 ℃, the thermal reduction time is 1.5h, and the mass ratio of graphene to bismuth telluride is 3: 7.
the invention provides a wave-absorbing material with high absorption strength and broadband, which is prepared by the preparation method of the graphene/bismuth telluride composite material.
The wave-absorbing material with high absorption strength and wide frequency band provided by the invention can show wide application prospect in military stealth aspect, especially in equipment such as military fighters, missiles, surface naval vessels and the like.
The invention provides a preparation method of a high-performance graphene/bismuth telluride microwave absorption composite material, which can realize high wave-absorbing strength and broadband absorption. The composite material has a highly porous structure, so that the dielectric constant and the refractive index of the material are reduced, the surface reflection of incident electromagnetic waves is reduced, and most of the electromagnetic waves can be incident into the material. In addition, the synergistic effect between the graphene material and the loaded bismuth telluride is utilized to realize the synergistic response to the electromagnetic waves, so that the absorption attenuation of the whole material system to the electromagnetic waves is improved, and the high absorption strength and the broadband absorption are both considered finally. The wave-absorbing material with high absorption strength and wide frequency band of the invention can show high application value in the fields of civil electromagnetic radiation interference resistance and military.
Compared with the prior art, the invention has the outstanding advantages that:
1) the composite material has a three-dimensional porous foam structure, and is favorable for reducing the surface reflection of the material to electromagnetic waves;
2) the preparation process is simple and universal;
3) the composite material has ultrahigh absorption strength which can reach-73 dB;
4) the effective absorption bandwidth is wider and can reach 8.9 GHz.
In a word, the broadband graphene/bismuth telluride wave-absorbing material with high absorption strength, which is prepared by the invention, has excellent properties, has a good application prospect in the wave-absorbing field, and particularly shows a great application value in the manufacture of military fighters, missiles, surface naval vessels and other equipment.
Drawings
Fig. 1 is a scanning electron microscope image of the graphene/bismuth telluride wave-absorbing material in example 1.
Fig. 2 is a reflectivity curve of the graphene/bismuth telluride wave-absorbing material under heat treatment at 210 ℃ for 1.5h in example 1.
FIG. 3 is a reflectivity curve of the graphene/bismuth telluride wave-absorbing material under heat treatment at 310 ℃ for 1.5h in example 2.
Detailed Description
The present invention is described in detail below with reference to specific embodiments and the attached drawings, the embodiments of the present invention are only used for facilitating the better understanding of the present invention for the personnel in the field, and the embodiments are not to be construed as limiting the scope of the present invention, and the personnel skilled in the art can make some insubstantial modifications and adjustments according to the content of the present invention described above, and all the modifications and adjustments belong to the scope of the present invention.
Experimental methods and tests in which specific conditions are not specified in the examples, generally according to conventional conditions and conditions described in manuals, or according to conditions recommended by the manufacturer; general equipment, materials, reagents and the like used are commercially available unless otherwise specified.
The method for testing the microwave frequency band reflectivity of the graphene/bismuth telluride wave-absorbing material comprises the following steps: based on a coaxial method testing device, the reflectivity of the material is tested in a 2-18GHz frequency band.
Example 1
A graphene/bismuth telluride high-strength absorption and broadband wave-absorbing material is prepared by the following specific steps:
1) bismuth telluride (162 mg) and graphene oxide powder (18 mg) are respectively weighed in two containers filled with 30 ml of 95% ethanol, stirred vigorously to obtain a bismuth telluride ethanol solution and a graphene oxide ethanol solution, and then the bismuth telluride ethanol solution and the graphene oxide ethanol solution are mixed, ultrasonically treated and uniformly stirred to form a stable colloidal solution.
2) And transferring the obtained colloidal solution into a polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, preserving the heat for 6 hours at 240 ℃, naturally cooling the reaction kettle to room temperature, taking out the graphene oxide/bismuth telluride composite material filled with ethanol, and completely replacing the graphene oxide/bismuth telluride composite material into a water system.
3) The above system was gradually frozen to a solid state at-50 ℃.
4) And (3) freezing and drying the obtained completely frozen graphene oxide/bismuth telluride and ice solid compound at-8 ℃ for 136 h. And then obtaining the dried graphene oxide/bismuth telluride composite material (figure 1). The size of the bismuth telluride is 100nm-3 mu m, and the aperture of the three-dimensional graphene oxide compound is 20 mu m-100 mu m.
5) In argon gas, carrying out heat treatment on the obtained dried graphene oxide/bismuth telluride composite material at 210 ℃ for 1.5h to finally obtain the graphene/bismuth telluride composite material with the mass ratio of 9: 1 (figure 2).
6) And (3) carrying out microwave frequency band 2-18GHz reflectivity test (Agilent vector network analyzer, N5230 type) on the obtained graphene/bismuth telluride wave-absorbing material. The graphene/bismuth telluride material has excellent wave-absorbing performance in a frequency band of 2-18 GHz. The mass ratio of graphene to bismuth telluride is 9: the sample of 1 was treated at 210 ℃ for 1.5h, and the sample reflectance was as low as-73 dB (sample thickness 5mm, FIG. 2).
Example 2
A graphene/bismuth telluride high-strength absorption and broadband wave-absorbing material is prepared by the following specific steps:
1) weighing bismuth telluride (18 mg) and graphene oxide powder (42 mg) in two containers filled with 70 ml of 95% ethanol, stirring vigorously to obtain a bismuth telluride ethanol solution and a graphene oxide ethanol solution, mixing the bismuth telluride ethanol solution and the graphene oxide ethanol solution, and performing ultrasonic treatment and stirring uniformly to form a stable colloidal solution.
2) And transferring the obtained colloidal solution into a polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, preserving the heat for 6 hours at 240 ℃, naturally cooling the reaction kettle to room temperature, taking out the graphene oxide/bismuth telluride composite material filled with ethanol, and completely replacing the graphene oxide/bismuth telluride composite material into a water system.
3) The above system was gradually frozen to a solid state at-50 ℃.
4) And (3) freezing and drying the obtained completely frozen graphene oxide/bismuth telluride and ice solid compound at-8 ℃ for 136 h. And then obtaining the dried graphene oxide/bismuth telluride composite material (figure 1). The size of the bismuth telluride is 100nm-3 mu m, and the aperture of the three-dimensional graphene oxide compound is 20 mu m-100 mu m.
5) In argon gas, carrying out heat treatment on the obtained dried graphene oxide/bismuth telluride composite material at 310 ℃ for 1.5h to finally obtain a graphene/bismuth telluride composite material with the mass ratio of 3: 7 (fig. 3).
6) And (3) carrying out microwave frequency band 2-18GHz reflectivity test (Agilent vector network analyzer, N5230 type) on the obtained graphene/bismuth telluride wave-absorbing material. The graphene/bismuth telluride material has excellent wave-absorbing performance in a frequency band of 2-18 GHz. The mass ratio of graphene to bismuth telluride is 3: the sample of 7 was processed at 310 ℃ for 1.5h to achieve an effective bandwidth of 8.9GHz (sample thickness 10 mm, FIG. 3).
In conclusion, the graphene/bismuth telluride wave-absorbing material is a wave-absorbing material with high absorption strength and wide frequency. The invention has excellent properties, has good application prospect in the field of wave absorption, and particularly has wide application value in the manufacture of equipment such as military fighters, missiles, surface naval vessels and the like.

Claims (7)

1. A preparation method of a high-performance graphene/bismuth telluride microwave absorption composite material is characterized by comprising the following steps:
1) respectively adding bismuth telluride powder and graphene oxide powder into an ethanol solution, violently stirring to obtain a bismuth telluride ethanol solution and a graphene oxide ethanol solution, and mixing, ultrasonically treating and uniformly stirring to form a stable colloidal solution;
2) transferring the obtained colloidal solution into a polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and reacting for 6 hours at 240 ℃; naturally cooling to room temperature, taking out the graphene oxide/bismuth telluride composite material filled with ethanol, and completely replacing the graphene oxide/bismuth telluride composite material into a water system;
3) gradually freezing the water system in liquid nitrogen to a solid state; the freezing temperature is-50 ℃;
4) freeze-drying the obtained completely frozen graphene oxide/bismuth telluride and ice solid compound at the temperature of-20-15 ℃ for 48-180h to obtain a dried graphene oxide/bismuth telluride composite material;
5) gradually heating in argon, and carrying out heat treatment reduction on the obtained dried graphene oxide/bismuth telluride composite material at the temperature of 200-600 ℃ for 0.5-6h to finally obtain the graphene/bismuth telluride wave-absorbing material;
6) carrying out a microwave frequency band 2-18GHz reflectivity test on the obtained graphene/bismuth telluride wave-absorbing material;
the mass ratio of the graphene to the bismuth telluride is 2.5-10: 0.5-8.
2. The preparation method according to claim 1, wherein the mass ratio of graphene to bismuth telluride is 9: 1 or 3: 7.
3. the method according to claim 1, wherein the freeze-drying time in step 4) is 136 hours and the freeze-drying temperature is-8 ℃.
4. The method according to claim 1, wherein the reduction temperature of the heat treatment in step 5) is 210 ℃; the thermal reduction time was 1.5 h.
5. The method according to claim 1, wherein the heat treatment of step 5) is carried out at a reduction temperature of 310 ℃ for a reduction time of 1.5 hours.
6. The graphene/bismuth telluride microwave absorption composite material obtained by the preparation method of any one of claims 1 to 5.
7. The graphene/bismuth telluride microwave absorbing composite material as set forth in claim 6 is applied to military stealth, including military fighters, missiles and surface naval vessel equipment.
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