CN109712769B - A kind of MXene-magnetic metal composite material and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of nano-magnetic composite material preparation, and discloses an MXene-magnetic metal composite material and a preparation method thereof. It consists of sheet-like MXene and magnetic metal nanoparticles uniformly supported on MXene. Disperse MXene in a mixed solution composed of ethylene glycol and water and stir evenly, then add magnetic metal salt and stir, then add NaOH to adjust the pH of the system to 8~14, then add hydrazine hydrate, stir evenly; heat to 60~120 ℃ and heat preservation for 0.2-8 h; cooling, separating, washing and drying to obtain the MXene-magnetic metal composite material. In the invention, ethylene glycol and water are used as solvents, MXene is used as a carrier, and magnetic cations are selectively adsorbed on the surface of MXene, heated at 60-120 ° C, and under the joint reduction action of hydrazine hydrate and ethylene glycol, the magnetic cations are gradually reduced by Reduced to magnetic nanoparticles, the finally prepared MXene-magnetic metal composite combines the properties of MXene and magnetic metal.

Description

A kind of MXene-magnetic metal composite material and preparation method thereof

technical field

The invention belongs to the field of nano-magnetic composite material preparation, in particular to an MXene-magnetic metal composite material and a preparation method thereof.

Background technique

MXenes are two-dimensional materials synthesized by extracting "A" layers from layered carbides or carbonitrides called MAX phases. The MAX phase has the general formula M _{n + 1} AX _n (n = 1, 2, 3), where M represents a transition metal element, A represents a IIIA or IVA element (such as Al, Ga, Si or Ge), X represents C and / or N. During the etching of the MAX phase into MXene, functional groups such as -O, -OH and -F were attached to the surface of the MXene, and the presence of these functional groups also provided the possibility for the loading of other nanoparticles. MXene has excellent electrical conductivity and can be modified by loading different particles to improve the comprehensive performance. Patent CN108091862A discloses an MXene-metal composite material and a preparation method thereof. The MXene-metal composite material is obtained by dispersing metal salt and MAX in HF, stirring, centrifuging and drying. The preparation process of the MXene-metal composite material is simple, and the performance of the lithium battery is good and the cycle rate is high.

Transition metal Ni and Co nanoparticles and their NiCo alloy particles are typical magnetic materials, which have a wide range of applications in the fields of catalysts, electromagnetic wave absorbing materials, energy storage, functional coating materials and high-performance electronic materials. However, due to the high Snoek limit of magnetic materials Ni and Co, it is easy to cause agglomeration, resulting in poor overall performance of the material. Combined with the above analysis, it is a rational choice to support magnetic particles Ni and/or Co and/or NiCo alloy particles on MXene.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an MXene-magnetic metal composite material and a preparation method thereof.

To achieve the above object, the technical scheme adopted by the present invention is as follows:

An MXene-magnetic metal composite material consists of sheet-like MXene and magnetic metal nanoparticles uniformly supported on MXene.

Preferably, the magnetic metal nanoparticles are Ni nanoparticles, Co nanoparticles or NiCo nanoparticles.

Preferably, the MXene is a lamellar structure with a thickness within 3 nm and a layer number of <5 layers.

The preparation method includes the following steps:

(1) Disperse MXene in a mixed solution composed of ethylene glycol and water and stir evenly, then add magnetic metal salt and stir, then add NaOH to adjust the pH of the system to 8-14, then add hydrazine hydrate and stir evenly;

(2) heating the mixed solution obtained in step (1) to 60-120 °C and keeping the temperature for 0.2-8 h;

(3) Cooling, separating, washing and drying the solution obtained in step (2) to obtain the MXene-magnetic metal composite material.

Preferably, in step (1), the volume ratio of ethylene glycol and water is (1~40):(1~9).

Preferably, in step (1), the added amount of the magnetic metal salt ensures that the ratio between the mass of the magnetic metal provided by the salt and the mass of the MXene is (1~9):(1~30).

Preferably, in step (1), the magnetic metal salt is one or more of nickel chloride, cobalt chloride, nickel nitrate, cobalt nitrate, nickel sulfate, cobalt sulfate, nickel acetate, and cobalt acetate.

Preferably, in step (1), the material ratio of hydrazine hydrate and magnetic metal salt is (1~30):(1~3).

Preferably, in step (1), the MXene is obtained by etching a MAX phase material, and the general formula of the MAX phase material is: Mn _{+ 1} AX _n , where M represents a transition metal element; A represents IIIA or IVA Element, X represents C and/or N, n = 1, 2, or 3.

Preferably, the MAX phase material is a MAX phase such as Ti ₃ AlC ₂ , Ti ₂ AlC, Ti ₃ AlCN or Ti ₂ SiC.

The formation principle of MXene-magnetic metal composites: the magnetic metal salts containing magnetic metal cations are uniformly dissolved in the MXene dispersion, and driven by the positive and negative adsorption, the magnetic metal cations are selectively adsorbed on the negatively charged MXene surface; In a suitable alkaline environment and temperature, using the reducibility of hydrazine hydrate, the magnetic metal cation is gradually reduced to a magnetic metal element, and finally the MXene-magnetic metal composite material is formed. Forms a synergistic reduction with hydrazine hydrate, contributing to the complete reduction of magnetic cations.

Beneficial effects of the present invention:

1. In the present invention, ethylene glycol and water are used as solvents, MXene is used as a carrier, and the magnetic cations are selectively adsorbed on the surface of MXene, heated at 60-120 °C, and under the joint reduction of hydrazine hydrate and ethylene glycol, the magnetic cations are removed. It is gradually reduced to magnetic nanoparticles, and the finally prepared MXene-magnetic metal composites combine the properties of MXene and magnetic metals, and have both good electrical conductivity and magnetic properties, which can be widely used in sensors, supercapacitors, energy storage, catalysts, Electromagnetic wave absorption and shielding materials and other fields.

2. The present invention has the advantages of less investment equipment, simple process, low cost, etc., and will not cause secondary pollution to the environment, can control the morphology and size of magnetic nanoparticles, and is suitable for large-scale preparation.

Description of drawings

Figure 1: Scanning electron microscope image of the MXene-magnetic metal composite material obtained in Example 1.

Figure 2: XRD patterns of MXene and MXene-magnetic metal composites obtained in Example 1.

Fig. 3: The electromagnetic wave shielding performance diagram of the MXene-magnetic metal composite material obtained in Example 1.

Figure 4: Scanning electron microscope image of the MXene-magnetic metal composite material obtained in Example 2.

Figure 5: Scanning electron microscope image of the MXene-magnetic metal composite obtained in Example 4.

Figure 6: Scanning electron microscope image of the MXene-magnetic metal composite material obtained in Example 5.

Figure 7: Scanning electron microscope image of the MXene-magnetic metal composite material obtained in Example 6.

Figure 8: Scanning electron microscope image of the MXene-magnetic metal composite obtained in Comparative Example 1.

Figure 9: XRD pattern of the MXene-magnetic metal composite obtained in Comparative Example 2.

Detailed ways

The technical solutions of the present invention will be further described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited thereto.

Example 1

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) Place 2 g of MAX phase material in a mixture of 40 mL of hydrochloric acid (40% by mass) and 2 g of lithium fluoride, etch at 35 °C for 24 h, wash and dry to obtain MXene;

(2) Disperse 80 mg of MXene prepared in step (1) in a mixture of 100 mL of ethylene glycol and 9 mL of deionized water, stir well, add 1.18 g of nickel chloride hexahydrate (NiCl ₂ 6H ₂ O) and Stir, then add NaOH to adjust the pH of the system to 10, then add 5 mL of hydrazine hydrate, and stir evenly;

(3) The mixed solution obtained in step (2) was heated to 80 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain MXene-magnetic metal composite material (counted as MXene-Ni).

The scanning electron microscope image of the MXene-magnetic metal composite prepared in this example is shown in FIG. 1 . It can be seen from Figure 1 that the Ni particles are uniformly supported on the MXene, and the MXene is in the shape of a gauze, indicating that the MXene has been successfully peeled off. between 200 nm.

The XRD patterns of the MXene and MXene-magnetic metal composites prepared in this example are shown in FIG. 2 . Figure 2a shows the XRD pattern of MXene. It can be seen that the XRD peaks of pure MXene of the present invention are consistent with the reported few-layer or single-layer MXene, which reflects that the step (1) carried out in the present invention is very successful, which is helpful for MXene. - Synthesis of magnetic metal composites. Figure 2b shows the XRD pattern of the MXene-magnetic metal composite material. It can be found from the figure that the peaks of MXene do not change much. At the same time, the main diffraction peaks of metal Ni can also be found in Figure 2b, including (111 ), (200) and (220) crystal planes, etc.; in addition, there are no other impurity peaks, indicating the compound requirements of the purity of the product. XRD results show that: MXene-magnetic metal composites can be easily prepared by the method of the present invention.

The MXene-magnetic metal composite material prepared in this example and paraffin were blended in a mass ratio of 3:2, and pressed into a ring with an inner diameter of 3.01 mm, an outer diameter of 7 mm, and a thickness of 1.4 mm. , Agilent N5234A) to test its electromagnetic wave shielding performance, the results are shown in Figure 3. In the frequency range of 2-18 GHz, its shielding performance is maintained at 30 dB, indicating that the MXene-magnetic metal composite prepared in this example has excellent electromagnetic wave shielding performance.

Example 2

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) 1 g of MAX phase material was placed in a mixture of 20 mL of hydrochloric acid (40% by mass) and 1 g of lithium fluoride, etched at 35 °C for 25 h, washed and dried to obtain MXene;

(2) Disperse 50 mg of MXene prepared in step (1) in a mixture of 48 mL of ethylene glycol and 6 mL of deionized water, stir well, add 0.59 g of nickel chloride hexahydrate (NiCl ₂ 6H ₂ O), and Stir, then add NaOH to adjust the pH of the system to 11, then add 2.5 mL of hydrazine hydrate, and stir evenly;

(3) The mixed solution obtained in step (2) was heated to 78 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain MXene-magnetic metal composite material (counted as MXene-Ni).

The scanning electron microscope image of the MXene-magnetic metal composite prepared in this example is shown in Figure 4. The results show that the magnetic metal Ni nanoparticles (100-300 nm in diameter) are evenly floating on the surface of MXene, and the SEM results confirm that the MXene-magnetic metal Successful preparation of composite materials.

Example 3

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) 1 g of MAX phase material was placed in a mixture of 20 mL of hydrochloric acid (40% by mass) and 1 g of lithium fluoride, etched at 35 °C for 25 h, washed and dried to obtain MXene;

(2) Disperse 100 mg of MXene prepared in step (1) in a mixture of 51 mL of ethylene glycol and 5 mL of water and stir evenly, and add 0.5 g of nickel nitrate hexahydrate (Ni(NO ₃ ) ₂ ·6H ₂ O) And stir, then add NaOH to adjust the pH value of the system to 10, then add 2 mL of hydrazine hydrate, stir evenly;

(3) The mixed solution obtained in step (2) was heated to 78 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain MXene-magnetic metal composite material (counted as MXene-Ni).

Example 4

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) Place 2 g of MAX phase material in a mixture of 40 mL of hydrochloric acid (40% by mass) and 2 g of lithium fluoride, etch at 35 °C for 24 h, wash and dry to obtain MXene;

(2) Disperse 80 mg of MXene prepared in step (1) in a mixture of 100 mL of ethylene glycol and 9 mL of deionized water, stir well, add 1.18 g of cobalt chloride hexahydrate (CoCl ₂ 6H ₂ O), and Stir, then add NaOH to adjust the pH of the system to 10, then add 5 mL of hydrazine hydrate, and stir evenly;

(3) The mixed solution obtained in step (2) was heated to 80 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain MXene-magnetic metal composite material (counted as MXene-Co).

The SEM image of the MXene-magnetic metal composite material prepared in this example is shown in Figure 5, which reveals that Co nanoparticles are uniformly distributed on the surface of MXene, indicating that the MXene-Co composite material can be successfully prepared by the method of the present invention.

Example 5

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) Place 2 g of MAX phase material in a mixture of 40 mL of hydrochloric acid (40% by mass) and 2 g of lithium fluoride, etch at 35 °C for 24 h, wash and dry to obtain MXene;

(2) Disperse 80 mg of MXene prepared in step (1) in a mixture of 100 mL of ethylene glycol and 9 mL of deionized water and stir well, add 0.6 g of cobalt chloride hexahydrate (CoCl ₂ 6H ₂ O) and 0.6g of nickel chloride hexahydrate (NiCl ₂ ·6H ₂ O) was stirred, then NaOH was added to adjust the pH of the system to 10, then 5 mL of hydrazine hydrate was added, and the mixture was uniformly stirred;

(3) The mixed solution obtained in step (2) was heated to 80 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain the MXene-magnetic metal composite material (counted as MXene-NiCo).

The scanning electron microscope image of the MXene-magnetic metal composite material prepared in this example is shown in Figure 6, which reveals that the NiCo nanoparticles are uniformly distributed on the surface of MXene, indicating that the MXene-Co composite material can be successfully prepared by the method of the present invention.

Example 6

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) Place 2 g of MAX phase material in a mixture of 40 mL of hydrochloric acid (40% by mass) and 2 g of lithium fluoride, etch at 35 °C for 24 h, wash and dry to obtain MXene;

(2) Disperse 80 mg of MXene prepared in step (1) in a mixture of 100 mL of ethylene glycol and 9 mL of deionized water, stir well, add 1 g of nickel chloride hexahydrate (NiCl ₂ 6H ₂ O) and Stir, then add NaOH to adjust the pH of the system to 10, then add 5 mL of hydrazine hydrate, and stir evenly;

(3) The mixed solution obtained in step (2) was heated to 80 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain MXene-magnetic metal composite material (counted as MXene-Ni).

The scanning electron microscope image of the MXene-magnetic metal composite prepared in this example is shown in Figure 7, and the MXene-magnetic metal composite was also successfully prepared.

Example 7

A preparation method of MXene-magnetic metal composite material, the steps are as follows:

(1) 1 g of MAX phase material was placed in a mixture of 20 mL of hydrochloric acid (40% by mass) and 1 g of lithium fluoride, etched at 35 °C for 24 h, washed and dried to obtain MXene;

(2) Disperse 50 mg of MXene prepared in step (1) in a mixture of 48 mL of ethylene glycol and 6 mL of deionized water and stir well, add 0.3 g of cobalt chloride hexahydrate (CoCl ₂ 6H ₂ O) and 0.3 g of nickel chloride hexahydrate (NiCl ₂ ·6H ₂ O) was stirred, then NaOH was added to adjust the pH of the system to 12, then 2.5 mL of hydrazine hydrate was added, and the mixture was stirred evenly;

(3) The mixed solution obtained in step (2) was heated to 78 °C and kept for 1 h;

(4) The solution obtained in step (3) is cooled, separated, washed with deionized water and ethanol for several times, and dried to obtain the MXene-magnetic metal composite material (counted as MXene-NiCo).

The invention uses magnetic metal nanoparticles to modify MXene, so as to improve the comprehensive performance of the MXene-magnetic metal composite material and expand the application range of the composite material. The key to the technology is that the particle size of the magnetic metal nanoparticles is uniform, and the magnetic metal nanoparticles can be uniformly loaded on MXene. In addition, MXene can not be oxidized even at high temperature due to the protective effect of hydrazine hydrate in the solution. However, it is very difficult for the magnetic metal nanoparticles to load MXene, and the inventor finally came up with the key technology of the present invention through unremitting efforts. Of course, the examples of such preparations are too numerous to enumerate according to the scope of application of the present invention.

Comparative Example 1

The difference from Example 1 is: in step (2), the amount of deionized water is 0 mL, that is, no deionized water is added;

The scanning electron microscope image of the MXene-magnetic metal composite prepared in this control example is shown in Figure 8. The results show that: Ni fibers and MXene coexist, and the magnetic Ni nanoparticles are not successfully and uniformly supported on MXene. Ni fibers are in the majority, and MXene also has agglomeration phenomenon, which is not conducive to the uniform loading of magnetic Ni nanoparticles on MXene. By comparing Example 1 and Comparative Example 1, it can be concluded that the preparation scheme of the present invention provides a good technology for uniformly loading MXene on magnetic Ni nanoparticles, is simple in operation and low in cost, and is a very promising application. invention.

Comparative Example 2

The difference with Example 1 is: in step (2), the consumption of ethylene glycol is 0 mL, that is, no ethylene glycol is added;

The XRD pattern of the MXene-magnetic metal composite (calculated as MXene-Ni@Ni(OH) ₂ ) prepared in this control example is shown in Figure 9. The results show that the existence of Ni(OH) 2 in the product is not conducive to Ni(OH) ₂ The reduction of ions, but the formation of Ni(OH) ₂ precipitation loaded on MXene, can not form uniform magnetic Ni nanoparticles uniformly loaded on MXene. By comparing Example 1 and Comparative Example 2, it can be concluded that under certain alkaline conditions, it is necessary to provide the presence of ethylene glycol and be miscible with deionized water to completely convert Ni ions into magnetic Ni nanoparticles. particles.

Claims (9)

1. a preparation method of MXene-magnetic metal composite material, it is characterized in that, MXene-magnetic metal composite material is made up of sheet-like MXene and magnetic metal nanoparticles uniformly loaded on MXene, and described magnetic metal nanoparticles are Ni nanometer particles. Particles, Co nanoparticles or NiCo nanoparticles; the preparation method of the MXene-magnetic metal composite material comprises the following steps: (1) Disperse MXene in a mixed solution composed of ethylene glycol and water and stir evenly, then add magnetic metal salt and stir, then add NaOH to adjust the pH of the system to 8-14, then add hydrazine hydrate and stir evenly; (2) heating the mixed solution obtained in step (1) to 60-120 °C and keeping the temperature for 0.2-8 h; (3) Cooling, separating, washing and drying the solution obtained in step (2) to obtain the MXene-magnetic metal composite material. 2. The preparation method of MXene-magnetic metal composite material according to claim 1, wherein in step (1), the volume ratio of ethylene glycol and water is (1~40):(1~9). 3. The preparation method of MXene-magnetic metal composite material according to claim 1, characterized in that: in step (1), the addition amount of the magnetic metal salt ensures that the quality of the magnetic metal provided by it is between the quality of the magnetic metal and the quality of the MXene. The ratio is (1~9):(1~30). 4. The preparation method of MXene-magnetic metal composite material according to claim 1, wherein in step (1), the magnetic metal salt is nickel chloride, cobalt chloride, nickel nitrate, cobalt nitrate, sulfuric acid One or more of nickel, cobalt sulfate, nickel acetate, and cobalt acetate. 5. The preparation method of MXene-magnetic metal composite material according to claim 1, wherein in step (1), the ratio of the amount of hydrazine hydrate and the amount of magnetic metal salt is (1~30): (1 ~3). 6 . The preparation method of MXene-magnetic metal composite material according to claim 1 , wherein in step (1), the MXene is obtained by etching a MAX phase material, and the general formula of the MAX phase material is: M 6 . _{n + 1} AX _n , where M represents a transition metal element; A represents a IIIA or IVA element, X represents C and/or N, and n=1, 2, or 3. 7 . The preparation method of MXene-magnetic metal composite material according to claim 6 , wherein the MAX phase material is Ti ₃ AlC ₂ , Ti ₂ AlC, Ti ₃ AlCN or Ti ₂ SiC. 8 . 8. A MXene-magnetic metal composite material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: the MXene-magnetic metal composite material is composed of sheet MXene and MXene uniformly loaded on MXene. The magnetic metal nanoparticles are composed of Ni nanoparticles, Co nanoparticles or NiCo nanoparticles. 9 . The MXene-magnetic metal composite material according to claim 8 , wherein the MXene is a lamellar structure with a thickness of less than 3 nm and a number of layers <5 layers. 10 .

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