阅读说明：本技术 一种CoFe/C复合材料及其制备方法和应用 (CoFe/C composite material and preparation method and application thereof ) 是由 杨海波 文博 王雷 邱云 胡帆帆 百晓宇 于 2019-10-22 设计创作，主要内容包括：本发明提供了一种鸟巢状Co<Sub>x</Sub>Fe<Sub>4-x</Sub>/C复合材料及其制备方法和应用,以四水合乙酸钴和六水氯化铁为金属源,2,5-二羟基对苯二甲酸为有机配体,通过掺入一定量的Fe<Sup>3+</Sup>来获得鸟巢状结构,以超纯水为反应溶剂,在油浴下回流一定时间后,将得到的黑色产物离心、洗涤和干燥,最后在氩气中热处理,得到鸟巢状CoxFe<Sub>4-x</Sub>/C复合材料。此种方法得到的CoxFe<Sub>4-x</Sub>/C复合材料为鸟巢状,因其独特结构和多组分使其作为吸波材料表现出极好的电磁吸波性能。(The invention provides a nest-shaped Co x Fe 4‑x The preparation method of/C composite material and its application are characterized by that it uses cobalt acetate tetrahydrate and iron chloride hexahydrate as metal source, uses 2, 5-dihydroxy terephthalic acid as organic ligand, and adds a certain quantity of Fe 3+ Obtaining a nest-shaped structure, taking ultrapure water as a reaction solvent, refluxing for a certain time under an oil bath, centrifuging, washing and drying the obtained black product, and finally performing heat treatment in argon to obtain nest-shaped CoxFe 4‑x a/C composite material. CoxFe obtained by the method 4‑x the/C composite material is nest-shaped, and the unique structure and the multiple components of the composite material enable the composite material to be used as a wave-absorbing material to show excellent electromagnetic wave-absorbing performance.)

1. A preparation method of a CoFe/C composite material is characterized by comprising the following steps:

step 1, mixing Co (CH)₃COO)₂·4H₂O and FeCl₃·6H₂Dissolving O in water to obtain a mixed solution A; dissolving 2, 5-dihydroxy terephthalic acid in water to obtain a mixed solution B; wherein, Co (CH)₃COO)₂·4H₂O and FeCl₃·6H₂The molar ratio of O is x: (4-x), wherein x is 3.4-2.6;

step 2, mixing the mixed solution B and the mixed solution A, reacting for 0.5-3 h at 90-110 ℃, washing and drying the obtained product to obtain a precipitate;

step 3, carrying out heat treatment on the obtained precipitate at 700-900 ℃ in a protective atmosphere to obtain Co_xFe_4-xa/C composite material.

2. The method of claim 1, wherein in step 2, after mixing mixture B and mixture A, 2, 5-dihydroxyterephthalic acid and Co (CH) are mixed together₃COO)₂·4H₂The molar ratio of O is: 2: (3.4-2.6).

3. The method for preparing the CoFe/C composite material according to claim 1, wherein in the step 2, the reaction is carried out at 90-110 ℃ for 1-3 h.

4. The method of claim 1, wherein the drying in step 2 is freeze-drying.

5. The method of claim 1, wherein in step 3, the shielding gas is argon.

6. The method for preparing the CoFe/C composite material according to claim 1, wherein in the step 3, the heat treatment temperature is 700-900 ℃ and the time is 2-5 h.

7. The method of claim 1, wherein in step 3, the temperature rise rate is 2-5 ℃/min.

8. A CoFe/C composite material obtained by the production process according to any one of claims 1 to 7.

9. Use of the CoFe/C composite material of claim 8 for electromagnetic wave absorption.

Technical Field

The invention belongs to the field of electromagnetic wave absorption, and particularly relates to a CoFe/C composite material and a preparation method and application thereof.

Background

With the development of radio, television and microwave technologies, electromagnetic pollution caused by excessive electromagnetic radiation has become another major pollution affecting people's health and information security. In general, attenuation and shielding of electromagnetic waves is certainly a good choice in order to reduce the influence of electromagnetic waves. In particular, electromagnetic waves can be more effectively attenuated by converting the electromagnetic waves into heat energy or dissipating the heat energy through interference, and therefore, designing and manufacturing high-performance wave-absorbing materials are the direction of research. In many previous researches, the multi-component wave absorbing material is found to have better wave absorbing performance than a single wave absorbing material, and the porous wave absorbing material can also improve the wave absorbing performance. Therefore, as the wave-absorbing material develops to a design concept of good impedance matching and light weight, more and more researchers focus on multi-component and micro-morphology design. The prior art has the following problems: firstly, from the aspect of the method, the conditions are harsh, and most of the solvent is organic solvent; secondly, the metal particles cannot be uniformly dispersed in the carbon layer, and the smaller volume cavity limits the entering of electromagnetic waves, so that the loss of the electromagnetic waves is reduced; finally, the absorption band of pure metal is relatively narrow, which is related to the eddy current formed by the conductive network structure.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides Co_xFe_4-x/C composite material, preparation method and application thereof, and prepared Co_xFe_4-xthe/C composite material has excellent wave-absorbing performance.

The invention is realized by the following technical scheme:

a preparation method of a CoFe/C composite material comprises the following steps:

step 1, mixing Co (CH)₃COO)₂·4H₂O and FeCl₃·6H₂Dissolving O in water to obtain a mixed solution A; dissolving 2, 5-dihydroxy terephthalic acid in water to obtain a mixed solution B; wherein, Co (CH)₃COO)₂·4H₂O and FeCl₃·6H₂The molar ratio of O is x: (4-x), wherein x is 3.4-2.6;

step 2, mixing the mixed solution B and the mixed solution A, reacting for 0.5-3 h at 90-110 ℃, washing and drying the obtained product to obtain a precipitate;

step 3, carrying out heat treatment on the obtained precipitate at 700-900 ℃ in a protective atmosphere to obtain Co_xFe_4-xa/C composite material.

Preferably, in step 2, after mixing mixture B and mixture A, 2, 5-dihydroxyterephthalic acid and Co (CH)₃COO)₂·4H₂The molar ratio of O is: 2: (3.4-2.6).

Preferably, in the step 2, the reaction is carried out for 1-3 h at 90-110 ℃.

Preferably, in step 2, the drying is freeze-drying.

Preferably, in step 3, the protective gas is argon.

Preferably, in the step 3, the heat treatment temperature is 700-900 ℃ and the time is 2-5 h.

Preferably, in step 3, the temperature rise rate is 2-5 ℃/min.

The CoFe/C composite material is prepared by the preparation method.

The CoFe/C composite material is applied to the aspect of electromagnetic wave absorption.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention adjusts the addition amount of iron ions to ensure that Co is added²⁺And Fe³The complex is in coordination relation with the ligand, thereby influencing the micro-morphology of the synthesized product and successfully preparing the nest-like Co_x/Fe_4-xThe MOF-74 bimetal organic framework material adopts water as a solvent, and has the advantages of simple method and high yield. Then the synthesized Co is treated under the protection of argon_x/Fe_4-xMOF-74 is subjected to a heat treatment, obtaining finally a nest-like Co_xFe_4-xa/C composite material. Of course, when the cobalt-iron ratio exceeds the range, a nest-like structure cannot be formed, and other morphological products can be formed, for example, when the cobalt-iron ratio is 2: 2, the product was short rod-like. The invention has the following improvements: firstly, water is used as a reaction solvent, so that the method is non-toxic and harmless, and is simple and high in yield; secondly, getThe bird nest-shaped appearance with a cavity with a larger volume is achieved, and the electromagnetic waves can enter the bird nest-shaped appearance; finally, the alloy and carbon are compounded, because the alloy has the characteristics of two components, compared with single-component magnetic metal, the magnetic metal alloy has stronger electron transfer and spin polarization coupling characteristics, has certain advantages in the field of electromagnetic wave absorption, and the carbon material has certain dielectric loss. Moreover, the nest-like Co prepared by the invention_xFe_4-xThe material of the/C composite material has uniform appearance and good crystallinity, the electromagnetic wave absorption performance of a sample is tested by a vector network analyzer, and Co can be found to be only 10% in mass fraction_xFe_4-xthe/C composite material has good wave-absorbing performance, the maximum reflection loss reaches-61.8 dB at the frequency of 12.7GHz, the effective frequency band width is 8.68GHz, and the matching thickness is 2.8 mm.

Drawings

FIG. 1 is a drawing of (a) bimetallic Co prepared in example 6₃/Fe₁-MOF-74 framework material and (b) Co after heat treatment₃Fe₁SEM pictures of the/C composite.

Fig. 2 shows the cobalt-iron ratio 2 of comparative example 1: 2 time bimetal Co₂/Fe₂-MOF-74 framework material and Co after heat treatment₂Fe₂SEM pictures of the/C composite.

FIG. 3 shows Co after heat treatment in example 6₃Fe₁XRD pattern of the/C composite material.

FIG. 4 shows Co prepared in example 6₃Fe₁Co with a/C composite filling of 10 wt%₃Fe₁Reflection loss value of the/C composite material.

FIG. 5 shows Co prepared in comparative example 1₂Fe₂Co with a/C composite filling of 10 wt%₂Fe₂Reflection loss value of the/C composite material.

FIG. 6 shows Co prepared in example 6₃Fe₁Cole-Cole circle diagram and C0 diagram of/C composite material.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention relates to Co_xFe_4-xThe preparation method of the/C composite material comprises the following steps:

(1) weighing x mmol Co (CH)₃COO)₂·4H₂O and (4-x) mmol FeCl₃·6H₂Dissolving O (x is 3.4-2.6) in 50mL of ultrapure water sufficiently after ultrasonic dispersion for half an hour to obtain a mixed solution A;

(2) weighing 2mmol of 2, 5-dihydroxy terephthalic acid, dissolving in a single-neck flask filled with 50mL of ultrapure water, and performing ultrasonic dispersion for half an hour to fully dissolve to obtain a mixed solution B;

(3) transferring the mixed solution B into an oil bath pan, slowly adding the mixed solution A into the mixed solution B, reacting for 0.5-3 h at 90-110 ℃, washing with ultrapure water and absolute ethyl alcohol, and freeze-drying for 24h to obtain a black precipitate.

(4) And placing the obtained black precipitate in a corundum porcelain boat, and carrying out heat treatment under the argon atmosphere, wherein the heat treatment temperature is 700-900 ℃, the heating rate is 2-5 ℃/min, and the heat preservation time is 2-5 h.