An MXene material, its exfoliation method and application

Abstract

The present invention provides a method for exfoliating MXene materials and an application thereof. The method for exfoliating MXene materials of the present invention comprises the following steps: etching MAX powder to obtain MXene precipitate; adding water to the MXene precipitate and performing vortex shear exfoliation to obtain an MXene suspension; centrifuging the MXene suspension and collecting the supernatant; repeating the vortex shear exfoliation and centrifugation in steps S2 to S3 on the supernatant for multiple times to obtain the MXene material; The MXene material prepared by the present invention using vortex shear exfoliation has a yield of about 90% and a conductivity of 1.01×10<supgt;6< / supgt; S m<supgt;‑1< / supgt>.

Description

Technical Field

[0001] The present invention relates to the technical field of MXene materials, and particularly to a method for exfoliating MXene materials and applications thereof. Background Art

[0002] MXene is a new type of two-dimensional material in addition to graphene, boron nitride nanosheets, and molybdenum disulfide nanosheets, referring to two-dimensional transition metal carbides, nitrides, or carbonitrides. A large number of studies have shown that MXene has more excellent electrical conductivity, film-forming properties, and hydrophilicity compared with other two-dimensional nanomaterials, and also has a large specific surface area, high mechanical strength, and good ductility. Therefore, MXene has been widely studied and applied in the fields of optics, electronics, energy storage, electromagnetic shielding, and biomedicine. At present, researchers have discovered a variety of preparation methods for MXene, mainly including hydrofluoric acid etching, hydrothermal etching, and Lewis acid salt etching. However, the exfoliation efficiency of these methods is generally lower than 70%, and the conductivity is lower than 8×10 5 S m -1 .

[0003] Based on the problems of low exfoliation efficiency and conductivity in the current preparation of MXene materials, it is necessary to improve this. Summary of the Invention

[0004] In view of this, the present invention provides a method for exfoliating MXene materials and applications thereof to solve or at least partially solve the technical problems existing in the prior art.

[0005] In a first aspect, the present invention provides a method for exfoliating MXene materials, including the following steps:

[0006] S1. Etch MAX powder to obtain multi-layer MXene precipitate;

[0007] S2. Add water to the multi-layer MXene precipitate and perform vortex shear exfoliation to obtain an MXene suspension;

[0008] S3. Centrifuge the MXene suspension and collect the supernatant;

[0009] S4. Repeat the vortex shear exfoliation and centrifugation in steps S2 to S3 for multiple times on the supernatant to obtain MXene materials;

[0010] Among them, the rotation speed in the vortex shear exfoliation is 100-1000 rpm, and the time is 5-100 min.

[0011] Preferably, in the method for exfoliating MXene materials, the MAX powder includes Ti3AlC2, Ti2Al C, at least one of Ti2AlN, Ti3AlN2, Ti4AlN3, Ti3AlCN, V2AlC, V3AlC2, V4AlC3, Nb2AlC, Nb3AlC2, Nb4AlC3, Mo2AlC, Mo3AlC2, Ta2AlC, Ta3AlC2, Ta4AlC3, Cr2AlC, TiNbAlC, TiVAlC, Ti2VAlC2, Ti2NbAlC2, Ti2TaAlC2, Ti2Ta2AlC3, VNbAlC, VCrAlC, Mo2TiAlC2, Mo2Ti2AlC3, Mo3VAlC3, Mo2Ga2AlC3, Cr2TiAlC2, TiVNbMoAlC3.

[0012] Preferably, for the method of exfoliating the MXene material, etching the MAX powder to obtain a multi-layer MXene precipitate, specifically including the following steps:

[0013] Add the MAX powder to an acidic solution containing a fluoride salt, stir at 40 - 60 °C for 30 - 40 h, and separate to obtain a multi-layer MXene precipitate.

[0014] Preferably, for the method of exfoliating the MXene material, before adding water to the multi-layer MXene precipitate and performing vortex shear exfoliation, it further includes: centrifugally washing the multi-layer MXene precipitate at 3000 - 5000 rpm until it is neutral.

[0015] Preferably, for the method of exfoliating the MXene material, centrifuging the MXene suspension and collecting the supernatant specifically includes the following steps:

[0016] Centrifuge the MXene suspension at 3000 - 5000 rpm for 10 - 30 min and collect the supernatant.

[0017] Preferably, for the method of exfoliating the MXene material, repeat the vortex shear exfoliation and centrifugation in steps S2 - S3 for the supernatant multiple times until the supernatant changes from black to green and then stop.

[0018] Preferably, for the method of exfoliating the MXene material, in the step of adding the MAX powder to an acidic solution containing a fluoride salt, the mass - volume ratio of the fluoride salt, MAX powder, and acidic solution is (15 - 20) g : (5 - 15) g : (180 - 220) mL;

[0019] The concentration of the acid is 8 - 12 mol / L.

[0020] In a second aspect, the present invention also provides an MXene material prepared by using the described preparation method.

[0021] Thirdly, the present invention also provides an application of the MXene material prepared by the described preparation method or the MXene material in the preparation of a conductive film.

[0022] The exfoliation method and application of an MXene material of the present invention have the following beneficial effects compared with the prior art:

[0023] 1. For the exfoliation method of the MXene material of the present invention, a vortex shear exfoliation device is used for vortex shear exfoliation to obtain the MXene material. Specifically, in the vortex shear exfoliation, the rotation speed is 100 - 1000 rpm and the time is 5 - 100 min. The MXene material prepared by vortex shear exfoliation can reach a yield of about 90%, and the conductivity can reach 1.01×10 6 S m -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 Is a photograph of the MXene material prepared in Example 1;

[0026] Figure 2 Is the XRD pattern of the MXene material prepared in Example 1;

[0027] Figure 3 Are the conductivity and sheet resistance of the MXene material prepared in Example 1;

[0028] Figure 4 Is the SEM image of the MXene material prepared in Example 1;

[0029] Figure 5 Is the SEM image of the MXene material prepared in Example 2;

[0030] Figure 6 Is the SEM image of the MXene material prepared in Example 3;

[0031] Figure 7 Is the SEM image of the MXene material prepared in Example 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] For a better understanding of the present invention rather than limiting the scope of the present invention, all numbers representing amounts, percentages, and other numerical values used in this application should be understood to be modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may vary according to the different desired properties to be obtained. Each numerical parameter should be regarded as being obtained at least in accordance with the reported significant figures and by means of conventional rounding methods.

[0034] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments. Additionally, in the description of this application, the term "comprising" means "including but not limited to". The various embodiments of the present invention may exist in a range format; it should be understood that the description in a range format is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the counted range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0035] The embodiments of this application provide a method for exfoliating MXene materials, including the following steps:

[0036] S1. Etch the MAX powder to obtain multi-layer MXene precipitate;

[0037] S2. Add water to the multi-layer MXene precipitate and perform vortex shear exfoliation to obtain a MXene suspension;

[0038] S3. Centrifuge the MXene suspension and collect the supernatant;

[0039] S4. Repeat the vortex shear exfoliation and centrifugation in steps S2 to S3 for the supernatant multiple times to obtain the MXene material;

[0040] Among them, the rotation speed in vortex shear exfoliation is 100 - 1000 rpm, and the time is 5 - 100 min.

[0041] It should be noted that for the exfoliation method of the MXene material in this application, vortex shear exfoliation is carried out using a vortex shear exfoliation device to obtain the MXene material. Specifically, the rotation speed in vortex shear exfoliation is 100 - 1000 rpm, and the time is 5 - 100 min. The MXene material prepared by vortex shear exfoliation has a yield of about 90%, and the conductivity (for a film with a thickness of 4 microns) can reach 1.01×10 6 S m -1 .

[0042] Specifically, in step S4, the supernatant is subjected to vortex shear exfoliation as in step S2 and centrifugation as in step S3, and this is repeated multiple times to obtain the MXene material.

[0043] In some embodiments, the vortex shear exfoliation device includes a shaker, a vortex mixer, etc.

[0044] In some embodiments, the MAX powder includes at least one of Ti3AlC2, Ti2AlC, Ti2AlN, Ti3AlN2, Ti4AlN3, Ti3AlCN, V2AlC, V3AlC2, V4AlC3, Nb2AlC, Nb3AlC2, Nb4AlC3, Mo2AlC, Mo3AlC2, Ta2AlC, Ta3AlC2, Ta4AlC3, Cr2AlC, TiNbAlC, TiVAlC, Ti2VAlC2, Ti2NbAlC2, Ti2TaAlC2, Ti2Ta2AlC3, VNbAlC, VCrAlC, Mo2TiAlC2, Mo2Ti2AlC3, Mo3VAlC3, Mo2Ga2AlC3, Cr2TiAlC2, TiVNbMoAlC3.

[0045] In some embodiments, etching the MAX powder to obtain a multi - layer MXene precipitate specifically includes the following steps:

[0046] Add the MAX powder to an acidic solution containing a fluoride salt, stir at 40 - 60 °C for 30 - 40 h, and separate to obtain the MXene precipitate.

[0047] Specifically, the fluoride salt includes but is not limited to LiF, NaF, KF, etc., and the acidic solution includes but is not limited to hydrochloric acid solution, sulfuric acid solution, nitric acid solution, etc.

[0048] In some embodiments, before adding water to the multi-layer MXene precipitate and performing vortex shear exfoliation, it further includes: adding water to the multi-layer MXene precipitate and centrifuging and washing it at 3000-5000 rpm until it is neutral.

[0049] In some embodiments, centrifuging the MXene suspension and collecting the supernatant specifically includes the following steps:

[0050] Centrifuge the MXene suspension at 3000-5000 rpm for 10-30 min and collect the supernatant.

[0051] In some embodiments, repeat the vortex shear exfoliation and centrifugation in steps S2-S3 for the supernatant multiple times until the supernatant changes from black to green and then stop.

[0052] In some embodiments, in the step of adding MAX powder to the acidic solution containing fluoride salt, the mass-volume ratio of the fluoride salt, MAX powder, and acidic solution is (15-20) g : (5-15) g : (180-220) mL;

[0053] The concentration of the acid is 8-12 mol / L.

[0054] Based on the same inventive concept, the embodiments of the present application further provide an MXene material prepared by using the above preparation method.

[0055] Based on the same inventive concept, the embodiments of the present application further provide an application of the MXene material prepared by the above preparation method or the MXene material in the preparation of a conductive film.

[0056] The following further illustrates the exfoliation method of the MXene material of the present application with specific examples. This part further illustrates the content of the present invention in combination with specific examples, but should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0057] Example 1

[0058] The embodiments of the present application provide a method for exfoliating an MXene material, including the following steps:

[0059] S1. Add 16 g of LiF to 200 mL of 9 mol / L hydrochloric acid, then add 10 g of Ti3AlC2, and stir at 50 °C for 36 h for etching to separate and obtain a multi-layer Ti3C2T x precipitate;

[0060] S2. Centrifuge and wash the multi-layer Ti₃C₂ at 3000 rpm until neutral.

[0061] S3. Add water to the washed Ti₃C₂T x precipitate in step S2, place it in a shaker for vortex shear exfoliation to obtain a Ti₃C₂T x suspension; wherein, the rotation speed in vortex shear exfoliation is 200 rpm and the time is 10 min.

[0062] S4. Centrifuge the Ti₃C₂T x suspension in step S3 at 5000 rpm for 10 min, and collect the supernatant.

[0063] S5. Repeat the vortex shear exfoliation and centrifugation of the supernatant in steps S2 - S3 for multiple times until the supernatant changes from black to light green and then stop, thus obtaining the MXene material (Ti₃CT x ).

[0064] The yield of the MXene material prepared in Example 1 is 92.2% (wherein, the calculation method of the yield is: the mass of the obtained MXene material / the mass of the multi-layer MXene, and the multi-layer MXene is the multi-layer Ti₃C₂T x precipitate in step S1).

[0065] Example 2

[0066] The embodiment of the present application provides a method for exfoliating MXene material, including the following steps:

[0067] S1. Add 16 g of LiF to 200 mL of 9 mol / L hydrochloric acid, then add 10 g of Ti₂AlC, and stir and etch at 50 °C for 36 h to separate and obtain a multi-layer Ti₂C₂T x precipitate.

[0068] S2. Centrifuge and wash the multi-layer Ti₂C₂T x precipitate at 3000 rpm until neutral.

[0069] S3. Add water to the washed Ti₂CT x precipitate in step S2, place it in a shaker for vortex shear exfoliation to obtain a Ti₂CT x suspension; wherein, the rotation speed in vortex shear exfoliation is 500 rpm and the time is 15 min.

[0070] S4. Centrifuge the Ti₂CT x suspension in step S3 at 5000 rpm for 10 min, and collect the supernatant.

[0071] S5. Repeat the vortex shear peeling and centrifugation in steps S2 - S3 for the supernatant multiple times until the supernatant changes from black to light green and then stop, thus obtaining the MXene material (Ti2CT x ).

[0072] The yield of the MXene material prepared in Example 2 is 85.8%.

[0073] Example 3

[0074] The embodiment of the present application provides a method for exfoliating MXene material, including the following steps:

[0075] S1. Add 16 g of LiF to 200 mL of 9 mol / L hydrochloric acid, then add 10 g of Ti3AlCN, and stir at 50 °C for 48 h for etching, and separate to obtain multi-layered Ti3CNT x precipitate;

[0076] S2. Centrifuge and wash the multi-layered Ti3CNT x precipitate at 3000 rpm until neutral;

[0077] S3. Add water to the Ti3CNT x precipitate washed in step S2, and place it in a shaker for vortex shear peeling to obtain a Ti3CNT x suspension; wherein, the rotation speed in the vortex shear peeling is 600 rpm and the time is 5 min;

[0078] S4. Centrifuge the Ti3CNT x suspension in step S3 at 5000 rpm for 10 min, and collect the supernatant;

[0079] S5. Repeat the vortex shear peeling and centrifugation in steps S2 - S3 for the supernatant multiple times until the supernatant changes from black to light green and then stop, thus obtaining the MXene material (Ti3CNT x ).

[0080] The yield of the MXene material prepared in Example 3 is 87.1%.

[0081] Example 4

[0082] The embodiment of the present application provides a method for exfoliating MXene material, including the following steps:

[0083] S1. Add 16 g of NaF to 200 mL of 12 mol / L hydrochloric acid, then add 10 g of Nb2AlC, and stir at 90 °C for 72 h for etching, and separate to obtain multi-layered Nb2CT x precipitate;

[0084] S2. The multi-layered Nb2CTx The precipitate was centrifuged and washed at 3000 rpm until neutral.

[0085] S3. Add water to the Nb2CT precipitate after washing in step S2, and place it in a shaker for vortex shear exfoliation to obtain an Nb2CT suspension; x wherein, the rotation speed in the vortex shear exfoliation is 300 rpm and the time is 20 min. x

[0086] S4. Centrifuge the Nb2CT suspension in step S3 at 5000 rpm for 10 min, and collect the supernatant; x

[0087]

[0088] S5. Repeat the vortex shear exfoliation and centrifugation in steps S2 - S3 for the supernatant multiple times until the supernatant changes from black to light green and then stop, thus obtaining the MXene material (Nb2CT x ).

[0089] The yield of the MXene material prepared in Example 4 is 90.4%.

[0090] Comparative Example 1

[0091] This comparative example provides a method for exfoliating MXene material, including the following steps:

[0091] S1. Add 1.85 g of LiF to 40 mL of 9 mol / L hydrochloric acid, then add 1.85 g of Ti3AlC2, and stir at 35 °C for 24 h for etching, and separate to obtain a multi-layer Ti3C2T precipitate; x

[0092] S2. Centrifuge the multi-layer Ti3C2T precipitate at 3000 rpm until neutral; x

[0093] S3. Add water to the Ti3C2T precipitate after washing in step S2, and completely freeze it at -20 °C, then thaw it at room temperature. Centrifuge the thawed multi-layer Ti3C2T dispersion at 3500 rpm for 1 h, and collect the supernatant. x x

[0094] The yield of the MXene material prepared in Comparative Example 1 is 39%, and the conductivity is 9.7×10 5 S m -1 .

[0095] Comparative Example 2

[0096] This comparative example provides a method for exfoliating MXene material, including the following steps:

[0097] ​​​​S1. Add 3.2 g of LiF to 40 mL of 9 mol / L hydrochloric acid, then add 2 g of Ti3AlC2, and etch at 25 °C with stirring for 48 h to obtain multilayer Ti3C2T x precipitate;

[0098] S2. Centrifuge and wash the multilayer Ti3C2T x precipitate at 5000 rpm until neutral;

[0099] S3. Add 100 mL of water to the washed Ti3C2T x precipitate in step S2, and ultrasonicate in an ice bath (0 °C) for 2 h to obtain a mixed solution;

[0100] S4. Centrifuge the mixed solution at 8000 rpm for 30 min and collect the supernatant.

[0101] The yield of the MXene material prepared in Comparative Example 2 was 79.3%, and the conductivity was 3.3×10 5 S m -1 .

[0102] The photo (solution) of the MXene material prepared in Example 1 is shown as Figure 1 shown.

[0103] The XRD pattern of the MXene material prepared in Example 1 is shown as Figure 2 shown.

[0104] The conductivity and sheet resistance of the MXene material prepared in Example 1 are shown as Figure 3 shown. Among them, the conductivity was measured after filtering the MXene liquid into an MXene film. Specifically, 5 mL of the MXene solution was filtered and vacuum dried at 50 °C to obtain the MXene film.

[0105] The SEM image of the MXene material prepared in Example 1 is shown as Figure 4 shown.

[0106] The SEM image of the MXene material prepared in Example 2 is shown as Figure 5 shown.

[0107] The SEM image of the MXene material prepared in Example 3 is shown as Figure 6 shown.

[0108] The SEM image of the MXene material prepared in Example 4 is shown as Figure 7 shown.

[0109] As can be seen from the above Examples 1 to 4, the MXene material obtained by the vortex shear exfoliation method of the present invention has a yield of about 90%, and the conductivity (film, thickness 4 microns) can reach 1.01×10 6 S m -1 . In the current methods, except for ultrasonic exfoliation, the exfoliation efficiency of other methods is generally lower than 70%, and the conductivity is lower than 8×10 5 S m -1 .

[0110] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for exfoliating MXene material, characterized in that, It includes the following steps: S1. Add 16 g of LiF to 200 mL of 9 mol / L hydrochloric acid, then add 10 g of Ti3AlC2, and stir at 50 °C for 36 h for etching. Separate to obtain multi-layer Ti3C2T x precipitate; S2. Precipitate the multi-layer Ti3C2T x and centrifuge and wash it at 3000 rpm until neutral; S3. Add water to the precipitate of Ti3C2T washed in step S2, and place it in a shaker for vortex shear exfoliation to obtain a Ti3C2T x suspension; wherein, the rotation speed in the vortex shear exfoliation is 200 rpm and the time is 10 min; x ​ S4. Centrifuge the Ti3C2T x suspension at 5000 rpm for 10 min and collect the supernatant; S5. Repeat the vortex shearing and peeling and centrifugation in steps S2 - S3 for the supernatant until the supernatant changes from black to light green and then stop, thus obtaining the MXene material.

2. A MXene material, characterized in that, It is prepared by using the peeling method as described in claim 1.

3. Application of the MXene material prepared by the peeling method as described in claim 1 or the MXene material as described in claim 2 in the preparation of a conductive film.

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