Preparation method of MXene self-supporting electromagnetic shielding film

Abstract

The invention relates to a preparation method of an MXene self-supporting electromagnetic shielding film, and the preparation method of the MXene self-supporting electromagnetic shielding film comprises the following steps: 1, mixing LiF powder with a preset mass and HCl with a preset concentration to prepare an etching solution; step 2, adding a precursor MAX of MXene into the etching solution, and stirring while adding to obtain a mixture of MXene and MAX; 3, keeping the obtained mixture at a preset temperature, and continuously stirring to obtain an etching product MXene; step 4, cleaning and separating the etching product by adopting repeated centrifugation for two or more times, so as to obtain supernate of the MXene dispersion liquid; and 5, transferring the supernatant of the MXene dispersion liquid into a vacuum suction filtration device for suction filtration to obtain the MXene self-supporting electromagnetic shielding film. The thickness of the MXene self-supporting electromagnetic shielding film prepared through the method is controllable, and compared with traditional Cu foil and Al foil, the MXene self-supporting electromagnetic shielding film has higher shielding effectiveness per unit thickness.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding. In particular, it relates to a method for preparing a self-supporting electromagnetic shielding film of MXene. Background Art

[0002] MXene is a new type of two-dimensional carbonitride metal compound with a chemical formula of Mn+1XnTx, where M represents transition metals such as Ti, Nb, V, etc., X represents C and / or N elements, Tx represents surface functional groups such as -OH, -O, and -F, and "ene" follows the naming method of graphene. Since it was first reported in 2012, MXene has been pursued by domestic and foreign researchers and has quickly become a research hotspot and difficulty of current new two-dimensional materials. Especially in 2016, MXene was first reported to have extremely high electromagnetic shielding performance, and it can achieve a shielding effectiveness of up to 100 dB at a micron thickness, which has attracted great attention from researchers in the field of electromagnetic shielding. MXene has extremely high electrical conductivity close to that of metal materials. At the same time, MXene has excellent mechanical properties, showing high strength and good flexibility. Compared with traditional metal shielding materials, MXene has obvious advantages of "wide, light, thin, and strong". In addition, MXene has rich surface functional groups, and the electromagnetic shielding effectiveness of MXene can be further regulated by chemical, physical and other methods, showing extremely strong tunability.

[0003] MXene has broad application prospects in the field of electromagnetic shielding. Its high efficiency and flexibility endow MXene with great design potential and will become a key alternative material to solve the important problem of electromagnetic compatibility brought by the intensive use of modern electronic devices. How to prepare a self-supporting electromagnetic shielding film of MXene is an urgent problem to be solved. Summary of the Invention

[0004] The present invention provides a method for preparing a self-supporting electromagnetic shielding film of MXene to solve the problem of regulating the electromagnetic shielding effectiveness of MXene by chemical, physical and other methods during the process of preparing the self-supporting electromagnetic shielding film of MXene.

[0005] To achieve the above object, in a first aspect, the present invention relates to a method for preparing a self-supporting electromagnetic shielding film of MXene, including:

[0006] Step 1: Mix a preset mass of LiF powder and a preset concentration of HCl to prepare an etching solution;

[0007] Step 2: Add the MXene precursor MAX, which is Ti3AlC2, to the etching solution while stirring to obtain a mixture.

[0008] Step 3: Continuously stir the mixture at a preset temperature to ensure that the obtained mixture achieves sufficient etching of the precursor MAX, and obtain an etched product;

[0009] Step 4: Wash and separate the etched product by centrifuging it two or more times to obtain the supernatant of the MXene dispersion;

[0010] Step 5: Transfer the supernatant of the MXene dispersion to a vacuum filtration device for filtration to obtain a self-supporting electromagnetic shielding film of MXene.

[0011] Preferably, in Step 1, specifically: Pour a preset mass of black LiF powder into a 9 M / L HCl solution, add it while stirring, and continuously stir for 5 - 10 min to obtain the etching solution;

[0012] Preferably, in Step 2, specifically: Add the MXene precursor MAX to the etching solution in batches, add it while stirring until the MXene precursor MAX is completely added to the etching solution to obtain the mixture;

[0013] Preferably, in Step 3, specifically: Place the mixture obtained in Step 2 in a heat preservation device, keep the temperature at 40 °C, and continuously stir the mixture for 24 h to achieve sufficient etching of the MXene precursor MAX and obtain the etched product;

[0014] Preferably, Step 4 specifically includes:

[0015] Dispense the etched product into a centrifuge tube for centrifugation to wash the etching residues;

[0016] Repeat dispensing the etched product into a centrifuge tube for centrifugation until the mixture in the centrifuge tube is uniformly viscous. Transfer the mixture in the centrifuge tube to a beaker, add deionized water for dilution, and place the MXene dispersion in an ultrasonic cleaner for ultrasonic treatment to peel the etched product and obtain the MXene dispersion;

[0017] Take the MXene dispersion and place it in a centrifuge tube for centrifugation, and take the supernatant of the MXene dispersion.

[0018] Preferably, during the process of dispensing the etched product into a centrifuge tube for centrifugation, the centrifugation speed is set to 3500 r / min, and the single centrifugation time is set to 5 min.

[0019] Preferably, in Step 5, specifically:

[0020] The supernatant of the obtained MXene dispersion is placed in a vacuum filtration device for filtration, and the usage amount of the supernatant of the MXene dispersion is adjusted to control the thickness of the filtration membrane, so as to obtain a MXene self-supporting electromagnetic shielding membrane with a preset thickness.

[0021] Preferably, step 5 is specifically: taking 5-15 mL of the supernatant of the obtained MXene dispersion separated, placing it in a vacuum filtration device for filtration, and obtaining a MXene self-supporting electromagnetic shielding membrane.

[0022] A preparation method of a MXene self-supporting electromagnetic shielding membrane involved in the present invention has the following beneficial effects compared with the prior art:

[0023] The present invention prepares a MXene self-supporting membrane by a thermal reduction method. The mixture after stirring and etching is sub-packed into a plurality of centrifuge tubes for centrifugation to wash the etching residues. The obtained viscous mixture is transferred to a beaker and diluted with an appropriate amount of deionized water. The diluted mixture is placed in an ultrasonic cleaner for ultrasonic treatment. An appropriate amount of the separated supernatant is taken and placed in a vacuum filtration device for filtration to obtain a MXene self-supporting electromagnetic shielding membrane with a certain thickness, providing a preparation scheme for the multi-scale structure regulation of MXene and the size of novel MXene materials. The MXene self-supporting electromagnetic shielding membrane material prepared by this method has a higher shielding effectiveness compared with traditional Cu foil and Al foil. Description of the Drawings

[0024] Figure 1 is the method flow of a preparation method of a MXene self-supporting electromagnetic shielding membrane in Embodiment 1 of the present invention. Figure 1 ;

[0025] Figure 2 is the schematic diagram of the method flow of a preparation method of a MXene self-supporting electromagnetic shielding membrane in Embodiment 1 of the present invention;

[0026] Figure 3 is the macroscopic morphology diagram of the MXene material membrane of a preparation method of a MXene self-supporting electromagnetic shielding membrane in Embodiment 1 of the present invention;

[0027] Figure 4 is the microscopic morphology diagram of the MXene material of a preparation method of a MXene self-supporting electromagnetic shielding membrane in Embodiment 1 of the present invention;

[0028] Figure 5 is the atomic-scale structure characterization diagram (XRD pattern and XAFS spectrum) of the MXene material of a preparation method of a MXene self-supporting electromagnetic shielding membrane in Embodiment 1 of the present invention;

[0029] Figure 6Comparison of the electromagnetic shielding effectiveness of the MXene self - supporting electromagnetic shielding film with a thickness of 15 μm prepared by the preparation method in Example 1 with that of traditional Cu foil (about 40 μm thick) and Al foil (about 50 μm thick). Detailed implementation manners

[0030] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the convenience of description, only parts related to the present invention rather than all structures are shown in the drawings.

[0031] Example 1

[0032] A preparation method of an MXene self - supporting electromagnetic shielding film, please refer to Figures 1-6 , including the following steps:

[0033] Step 1: Prepare an etching solution by mixing a preset mass of LiF powder and a preset concentration of HCl.

[0034] Specifically: Pour a preset mass of black LiF powder into a 9 M / L HCl solution, add it while stirring, and continuously stir for 5 - 10 min to obtain the etching solution. The above - mentioned preset mass of black LiF powder can be 1 - 3 g (including 1 g or 3 g).

[0035] Step 2: Add the MXene precursor MAX to the etching solution, add it while stirring to obtain a mixture, where the MXene precursor MAX is Ti3AlC2.

[0036] Specifically: Add the MXene precursor MAX to the etching solution in batches, add it while stirring until the MXene precursor MAX is completely added to the etching solution to obtain a mixture.

[0037] Step 3: Keep the obtained mixture at a preset temperature and continuously stir to achieve sufficient etching of the precursor MAX to obtain an etching product.

[0038] Specifically, place the mixture obtained in Step 2 in a heat - preservation device, keep the temperature at 40 °C, and continuously stir the mixture for 24 h to achieve sufficient etching of the MXene precursor MAX to obtain an etching product.

[0039] Step 4: Wash and separate the etching product by centrifuging twice or more to obtain the supernatant of the MXene dispersion.

[0040] Specifically, it includes Steps 41 - 43:

[0041] Step 41: The etched products are dispensed into centrifuge tubes and centrifuged to clean the etched residues.

[0042] Specifically, the centrifugation and cleaning process is repeated until the mixture in the centrifuge tube is uniformly viscous. At this time, the pH value of the mixture should be neutral. In this step, the centrifugation speed is set at 3500 r / min, and the single centrifugation time is set at 5 min.

[0043] Step 42: The etched products are repeatedly dispensed into centrifuge tubes and centrifuged until the mixture in the centrifuge tube is uniformly viscous. The mixture in the centrifuge tube is transferred to a beaker and diluted with deionized water. The MXene dispersion is placed in an ultrasonic cleaner for ultrasonic treatment to exfoliate the etched products and obtain the MXene dispersion. In this embodiment, the mixture sufficiently stirred in Step 3 is taken out and equally poured into 4 centrifuge tubes, and deionized water is added to 100 mL.

[0044] Step 43: The MXene dispersion is placed in a centrifuge tube for centrifugation, and the supernatant of the MXene dispersion is taken to separate the etched products with insufficient etching and the exfoliated products with insufficient exfoliation.

[0045] In the above Steps 41 to 43, during the process of dispensing the etched products into centrifuge tubes and centrifuging, the centrifugation speed is set at 3500 r / min, and the single centrifugation time is set at 5 min. This centrifugation operation is repeated multiple times until the mixture in the centrifuge tube no longer layers and is turbid and opaque.

[0046] Step 5: The supernatant of the MXene dispersion is transferred to a vacuum filtration device for filtration to obtain the MXene self-supporting electromagnetic shielding film.

[0047] In this step, the thickness of the filtration membrane can be controlled by adjusting the usage amount of the supernatant.

[0048] Specifically, the supernatant of the separated MXene dispersion is placed in a vacuum filtration device for filtration, and the usage amount of the supernatant of the MXene dispersion is adjusted to control the thickness of the filtration membrane to obtain the MXene self-supporting electromagnetic shielding film with a preset thickness.

[0049] In one example, step 2 is specifically as follows: Take 1 g of MAX (Ti3AlC2) and slowly add it to the mixture obtained in step 1. The feeding time should not exceed 10 min, and stir while adding; step 3 is specifically as follows: Place the mixture obtained in step 2 and the magnetic stirring bar in a ceramic crucible, seal the ceramic crucible, place it in a constant temperature device, select a constant temperature of 40 °C, and continuously stir the mixture placed in the ceramic crucible for 24 h; step 42 is specifically as follows: Place the mixture in step 41 in a larger glass beaker and add 100 mL of deionized water for dilution; place the mixture in step 41 in an ultrasonic cleaner and perform ultrasonic treatment on the mixture for 3 h; in step 5, take 5 - 15 mL of the supernatant of the separated MXene dispersion liquid and place it in a vacuum filtration device for filtration to obtain a self-supporting electromagnetic shielding film of MXene. The amount of the supernatant is basically linearly related to the thickness. The larger the amount, the thicker the film. Generally, a film about 10 μm thick is prepared with 10 mL of the supernatant.

[0050] The comparison of the electromagnetic shielding effectiveness of the 15-μm-thick MXene film prepared in this example with that of traditional Cu (about 40-μm thick) foil and Al foil (about 50-μm thick) shielding effectiveness is as Figure 6 shown.

[0051] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0052] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing a MXene self-supporting electromagnetic shielding film, characterized in that: include: Step 1: Mixing a preset mass of LiF powder and a preset concentration of HCl to prepare an etching solution; Step 2: adding a precursor of MXene MAX to the etching solution, stirring while adding to obtain a mixture, wherein the precursor of MXene MAX is Ti3AlC2; Step 3: maintaining the obtained mixture at a preset temperature and continuously stirring it to achieve sufficient etching of the precursor MAX to obtain an etching product; Step 4: Wash and separate the etched product by repeated centrifugation two or more times to obtain a supernatant of the MXene dispersion; Step 5: Transfer the supernatant of the MXene dispersion to a vacuum filtration device for filtration to obtain a MXene self-supporting electromagnetic shielding film.

2. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 1, characterized in that: The step 1 is specifically as follows: pouring a preset mass of LiF black powder into a 9M / L HCl solution, stirring while adding, and continuously stirring for 5-10 minutes to obtain the etching solution.

3. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 2, characterized in that: The step 2 specifically comprises: adding the MXene precursor MAX to the etching solution in batches, stirring while adding until the MXene precursor MAX is completely added to the etching solution to obtain the mixture.

4. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 1, characterized in that: The step 3 is specifically to place the mixture obtained in step 2 in a heat preservation device, maintain the temperature at 40° C., and continuously stir the mixture for 24 hours to fully etch the MXene precursor MAX to obtain the etching product.

5. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 1, characterized in that: The step 4 specifically includes: The etching products are divided into centrifuge tubes for centrifugation to clean the etching residues; Repeatedly packing the etching product into centrifuge tubes for centrifugation until the mixture in the centrifuge tube is uniform and viscous, transferring the mixture in the centrifuge tube to a beaker and adding deionized water for dilution, placing the MXene dispersion in an ultrasonic cleaning machine for ultrasonic treatment to achieve stripping of the etching product, and obtaining a MXene dispersion; The MXene dispersion is placed in a centrifuge tube for centrifugation, and the supernatant of the MXene dispersion is taken.

6. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 5, characterized in that: During the process of packing the etching products into centrifuge tubes for centrifugation, the centrifugal speed is set to 3500 r / min and the single centrifugation time is set to 5 min.

7. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 1, characterized in that: The step 5 is specifically as follows: The supernatant of the separated MXene dispersion is placed in a vacuum filtration device for filtration, and the amount of the supernatant of the MXene dispersion used is adjusted to control the thickness of the filtration membrane to obtain a MXene self-supporting electromagnetic shielding film of a preset thickness.

8. The method for preparing a MXene self-supporting electromagnetic shielding film according to claim 1, characterized in that: The step 5 is specifically as follows: taking 5-15 mL of the supernatant of the separated MXene dispersion, placing it in a vacuum filtration device for filtration, and obtaining a MXene self-supporting electromagnetic shielding film.

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