CN108620003A - The telescopic preparation method with the high MXene/ graphene composite aerogels for being electromagnetically shielded effect - Google Patents

Abstract

The invention discloses a preparation method of a scalable MXene/graphene composite airgel with high electromagnetic shielding effect. The method combines MXene and reduced graphene oxide, and uses a modifier to induce the reduction of graphene oxide With MXene and cold-drying treatment, a three-dimensional network-like composite airgel with rich pore structure is formed. In the present invention, by uniformly mixing reduced graphene oxide and MXene dispersion liquid, introducing a modifier, and finally performing cold-drying treatment, a scalable MXene/graphene composite airgel with high electromagnetic shielding effect can be obtained, reducing the The bulk density of MXene constructs a new macroscopic morphology, and its mechanical properties are extremely excellent, and it is scalable, which promotes the feasibility of MXene application in the aerospace field.

Description

Scalable MXene/graphene composite airgel with high electromagnetic shielding effect Preparation

technical field

The invention belongs to the technical field of nanocomposite material preparation, and relates to a preparation method of MXene/graphene composite airgel.

Background technique

MXene is a two-dimensional transition metal carbide or carbonitride with a graphene-like structure, which is generally prepared by etching or stripping off the A-layer elements in the MXA phase. For the MAX phase, M refers to transition metal elements, A usually refers to group IIIA and IVA elements, and X refers to carbon or nitrogen.

MXene has the same excellent electrical conductivity as graphene. It is a new type of two-dimensional material with metal conductive properties and has extremely excellent electromagnetic shielding properties. However, the general MXene material exists macroscopically in the form of powder or film, and its structure is extremely dense, resulting in high density, and the structure is easily damaged and has no scalability, which seriously affects the application of MXene in the field of electromagnetic shielding. Because in practical applications, it is generally hoped that the electromagnetic shielding material should be as light as possible, and have excellent mechanical properties, especially for the aerospace field. In addition, because the flexibility of the MXene sheet is not as good as that of graphene, it is difficult to form a three-dimensional graphene aerogel like graphene. However, people are eager to find a way to build a graphene-like aerogel. Three-dimensional structure MXene. From a large number of literatures that have been reported, it is known that graphene aerogels with three-dimensional morphology can be easily formed by using reduced graphene oxide. Moreover, the surface of reduced graphene oxide is rich in oxygen-containing functional groups, and there is a strong electrostatic repulsion between layers, so the water dispersion of reduced graphene oxide is a negatively charged colloid, which can exist stably for several months without precipitation. . The surface of MXene obtained by hydrofluoric acid etching also contains hydrophilic groups such as hydroxyl groups and epoxy groups, and its aqueous dispersion is also negatively charged. Therefore, reduced graphene oxide and MXene can be dispersed together very uniformly, and can easily form a stable colloid, which provides a favorable theoretical support for the construction of lightweight MXene/graphene composite airgel.

Contents of the invention

In order to solve the problem that the ordinary MXene material has a high density, a fragile structure and no scalability, which limits its further application in the field of electromagnetic shielding, the present invention provides a scalable MXene/graphene composite with high electromagnetic shielding effect Airgel preparation method. In the present invention, by uniformly mixing reduced graphene oxide and MXene dispersion liquid, introducing a modifier, and finally performing cold-drying treatment, a scalable MXene/graphene composite airgel with high electromagnetic shielding effect can be obtained, reducing the The packing density of MXene builds a new macroscopic morphology, and its mechanical properties are extremely excellent, and it is scalable, which promotes the feasibility of MXene in aerospace applications.

The purpose of the present invention is achieved through the following technical solutions:

A preparation method of scalable MXene/graphene composite airgel with high electromagnetic shielding effect, by compounding MXene and reduced graphene oxide, using modifiers to induce reduction of graphene oxide and MXene and cold-drying treatment A three-dimensional network-like composite airgel with rich pore structure is formed. The specific implementation steps are as follows:

Step 1. Disperse the reduced graphene oxide in deionized water to obtain a solution A having a reduced graphene oxide solution concentration of 4-10 mg mL ⁻¹ .

In this step, the reduced graphene oxide is a large single-layer reduced graphene oxide with a size of 2-5 μm.

Step 2: Mix the MXene dispersion with a concentration of 1 to 3 mg mL ^-1 and solution A at a mass ratio of 1 to 10:1 to obtain a mixed solution B.

In this step, the MXene dispersion is prepared by etching Ti ₃ AlC ₂ with hydrofluoric acid.

Step 3: The mixed solution B is magnetically stirred and then ultrasonically treated to obtain a uniformly mixed solution C.

In this step, the rotational speed of the magnetic stirring is 200-600 r/min, and the duration is 10-30 min.

In this step, the ultrasonic power is 100-300 W, and the ultrasonic time is 10-30 min.

Step 4: Add the modifying agent into the solution C, perform magnetic stirring and then perform ultrasonic treatment to obtain the solution D.

In this step, the modifying agent is one or a combination of dopamine, chitosan, cellulose nanofibers, sodium alginate and polyvinyl alcohol.

In this step, the amount of the modifying agent is 3-5 wt% of the solution D.

In this step, the rotational speed of the magnetic stirring is 200-600 r/min, and the duration is 10-30 min.

In this step, the ultrasonic power is 100-300 W, and the ultrasonic time is 10-30 min.

Step five, the solution D is freeze-dried to obtain MXene/graphene composite airgel.

In this step, the freeze-drying temperature is -50~-80°C, and the time is 48 h.

The stretchable MXene/graphene composite airgel prepared by the above method can be applied in the field of electromagnetic shielding in aerospace.

Compared with the prior art, the present invention has the following advantages:

1. The present invention utilizes the characteristic that reduced graphene oxide is easy to form a three-dimensional structure, combines reduced graphene oxide and MXene, and adds a modifier to induce MXene to form a three-dimensional network structure, which greatly reduces the macroscopic accumulation density of MXene materials , the large sheet structure of MXene and reduced graphene oxide will wrap the modifier so as to maintain the inherent high conductivity, and the modifier will enhance the mechanical strength of the overall composite airgel and endow it with excellent scalability, Finally, a three-dimensional network and good scalability of MXene/graphene composite airgel was constructed, and a new MXene macroscopic stacking morphology was created, which broadened its application field.

2. The present invention can further enhance the practical application potential of MXene in the field of electromagnetic shielding by introducing graphene with excellent mechanical properties into MXene.

3. The method of the present invention is extremely simple, and the cost of the raw materials used is low, which is very easy for industrialized mass production.

4. Compared with conventional graphene aerogels, the composite airgel prepared by the present invention has extremely excellent electrical conductivity and scalability.

Description of drawings

Fig. 1 is the stretchable MXene/graphene composite airgel sample with high electromagnetic shielding effect prepared by embodiment 1;

Fig. 2 is the scanning electron micrograph of the stretchable MXene/graphene composite aerogel with high electromagnetic shielding effect prepared in embodiment 2;

FIG. 3 is a diagram of the electromagnetic shielding effectiveness of the stretchable MXene/graphene composite material with high electromagnetic shielding effect prepared in Examples 1-3.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the examples, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered by the present invention within the scope of protection.

Example 1:

The scalable MXene/graphene composite airgel preparation method with high electromagnetic shielding effect provided by the present embodiment is realized through the following steps:

Step 1, prepare the reduced graphene oxide into a reduced graphene oxide solution with a concentration of 4 mg mL ^-1 , namely solution A.

Step 2: Etching Ti ₃ AlC ₂ with hydrofluoric acid to prepare MXene dispersion, and controlling its concentration to 1.5 mg mL ^-1 with deionized water. Mix the MXene dispersion with solution A at a mass ratio of 1:1 to obtain solution B.

Step 3. The solution B was magnetically stirred at a speed of 600 r/min for 30 minutes and then subjected to ultrasonic treatment for 40 minutes to obtain a solution C with an ultrasonic power of 200 W.

Step 4. Dissolve polyvinyl alcohol in deionized water, add it to solution C at a ratio of 5 wt%, and then magnetically stir it at 400 r/min for 20 min, and then perform 10 min of ultrasonic power at 100 W. Ultrasonic treatment, to obtain the composite solution D.

Step 5. Freeze-dry the homogeneously mixed composite solution D at -60° C. for 48 hours to obtain MXene/graphene composite airgel.

Fig. 1 is the stretchable MXene/graphene composite airgel sample with high electromagnetic shielding effect prepared in this embodiment. It can be seen from Figure 1 that the MXene/graphene composite airgel prepared in this example has excellent compressibility and stretchability.

Example 2:

The preparation method of the scalable MXene/graphene composite airgel with high electromagnetic shielding effect provided by the present embodiment is realized through the following steps:

Step 1, prepare the reduced graphene oxide into a reduced graphene oxide solution with a concentration of 10 mg mL ^-1 , namely solution A.

Step 2: Etching Ti ₃ AlC ₂ with hydrofluoric acid to prepare an MXene dispersion, and preparing a concentration of 3 mg mL ^-1 with deionized water. Mix the MXene dispersion with solution A at a mass ratio of 1:2 to obtain solution B.

Step 3. The solution B was magnetically stirred at a speed of 300 r/min for 20 minutes, and then ultrasonically treated for 30 minutes to obtain a solution C. The ultrasonic power was 100 W.

Step 4: Prepare a tris buffer solution with a pH of 8.5, then add solution C, and stir evenly, then add 4 wt% dopamine and stir magnetically at 400 r/min for 20 minutes, and then use 100W ultrasonic Ultrasonic treatment was carried out for 10 min at high power to obtain composite solution D.

Step 5. Freeze-dry the uniformly mixed composite solution D at -80° C. for 48 hours to obtain MXene/graphene composite airgel.

The scanning electron micrograph of the stretchable MXene/graphene composite airgel with high electromagnetic shielding effect prepared in this example is shown in Figure 2. It can be seen from Figure 2 that the MXene/graphene composite airgel prepared in this example has a three-dimensional network structure, and the pore size is large, reaching hundreds of microns, thus endowing it with a stretchable performance similar to that of a sponge.

Example 3:

The scalable MXene/graphene composite airgel preparation method with high electromagnetic shielding effect provided by the present embodiment is realized through the following steps:

Step 1, prepare the reduced graphene oxide into a reduced graphene oxide solution with a concentration of 6 mg mL ⁻¹ , namely solution A.

Step 2, preparing MXene dispersion by etching Ti ₃ AlC ₂ with hydrofluoric acid, and controlling its concentration to 2 mg mL ^-1 with deionized water. Mix the MXene dispersion with solution A at a mass ratio of 1:3 to obtain solution B.

Step 3. The solution B was magnetically stirred at a rotation speed of 500 r/min for 10 minutes, and then ultrasonically treated for 30 minutes to obtain a solution C. The ultrasonic power was 150 W.

Step 4: Add 3 wt% of cellulose nanofibers to solution C, then magnetically stir it at 200 r/min for 150 min, and then perform ultrasonic treatment at 150 W ultrasonic power for 200 min to obtain composite solution D.

Step 5. Freeze-dry the uniformly mixed composite solution D at -70° C. for 48 hours to obtain MXene/graphene composite airgel.

The electromagnetic shielding effectiveness diagram of the stretchable MXene/graphene composite material with high electromagnetic shielding effect prepared in Examples 1-3 is shown in FIG. 3 . It can be seen from Figure 3 that with the increase of the amount of MXene added, the electromagnetic shielding performance of the obtained composite airgel is enhanced. The electromagnetic shielding effectiveness of the composite airgel obtained in Example 1 can reach 20-25 dB, which is much higher than the minimum requirement for electromagnetic shielding effectiveness in practical applications. The electromagnetic shielding effectiveness of the composite airgel obtained in Example 3 is as high as 30-50 dB, so it has great potential in the field of electromagnetic shielding applications in aerospace.

Claims (9)

1. a kind of telescopic preparation method with the high MXene/ graphene composite aerogels for being electromagnetically shielded effect, feature Being the method, steps are as follows：

Step 1: redox graphene is scattered in deionized water, it is 4 ~ 10 to obtain redox graphene solution concentration mg mL^-1Solution A；

Step 2: by a concentration of 1 ~ 3 mg mL^-1MXene dispersion liquids and solution A according to mass ratio be 1 ~ 10:1 ratio is mixed It closes, obtains mixed solution B；

It is ultrasonically treated again Step 3: mixed solution B first to be carried out to magnetic agitation, obtains uniformly mixed solution C；

Step 4: modifying agent is added in solution C, first carries out magnetic agitation and be ultrasonically treated again, obtain solution D；

Step 5: solution D is freeze-dried, MXene/ graphene composite aerogels are obtained.

2. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the redox graphene is the redox graphene of large stretch of single layer, and size is 2 ~ 5 μm.

3. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the MXene dispersion liquids are by hf etching Ti₃AlC₂And be prepared into.

4. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the rotating speed of the magnetic agitation is 200 ~ 600 r/min, and the duration is 10 ~ 30 min.

5. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the ultrasonic power is 100 ~ 300 W, and ultrasonic time is 10 ~ 30 min.

6. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the modifying agent is dopamine, chitosan, cellulose nano-fibrous, sodium alginate and poly- second It is a kind of or a combination thereof in enol.

7. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the dosage of the modifying agent is 3 ~ 5 wt% of solution D.

8. the telescopic MXene/ graphene composite aerogels that there is height to be electromagnetically shielded effect according to claim 1 Preparation method, it is characterised in that the temperature of the freeze-drying is -50 ~ -80 DEG C, and the time is 48 h.

9. the telescopic MXene/ with high electromagnetic shielding effect prepared by claim 1-8 any claim the methods Graphene composite aerogel is applied in the electromagnetic shielding field in terms of aerospace.