A method for preparing Mo-based MXene heterojunction

Abstract

The present invention belongs to the field of nanomaterial preparation, and particularly relates to a method for preparing a Mo-based MXene heterojunction. The method comprises the following steps: mixing a Mo2Ga2C2 MAX material, an ammonium halide, a small molecule intercalant, and water under anaerobic conditions, followed by a heating reaction to produce a Mo-based MXene heterojunction; the concentration of the ammonium halide in the water being ≥6 mol / L; the small molecule intercalant having a relative molecular mass of 40 to 100 and a concentration of ≥3 mol / L in the water; and the heating reaction temperature being >180°C. The present invention utilizes ammonium halide and a small molecule intercalant, both of which offer improved safety and stability, to etch a MAX precursor and prepare Mo-based MXene heterojunctions in large quantities in a single step. The preparation process is simple, efficient, low-cost, and easily mass-producible. It is safe and reliable, avoids the use of the traditional hazardous reagent HF, and eliminates the need for the introduction of strong acids or bases.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterial preparation, and in particular relates to a method for preparing a Mo-based MXene heterojunction. Background Art

[0002] With rapid socioeconomic development and growing energy demand, the extensive use of fossil fuels has led to serious environmental problems, such as the greenhouse effect, acid rain, and air pollution. Simultaneously, the concept of sustainable development has prompted the search for clean, efficient, and renewable energy solutions. In this context, novel renewable energy systems, such as secondary batteries, supercapacitors, and fuel cells, have emerged as important means of energy storage and conversion. Two-dimensional transition metal carbides (MXenes) have garnered significant attention due to their unique physicochemical properties. Effective methods for modifying MXenes typically include atomic doping, composite material preparation, surface end-group modification, and heterojunction formation. MXene heterojunctions combine the advantages of heterojunctions—metallic conductivity or narrow-bandgap semiconductor properties, an open layered structure, weak interlayer interactions, and a high specific surface area—with the unique properties of the heterojunction. This allows for targeted manipulation of the overall material's performance, structure, and morphology, offering promising applications in secondary ion batteries, catalysis, optics, and other fields.

[0003] The preparation of MXene heterojunctions typically begins with chemical etching of the precursor MAX phase, followed by vapor deposition, electrochemical deposition, hydrothermal synthesis, self-assembly, heat treatment, and liquid-phase exfoliation to obtain the MXene heterojunction. Liquid-phase exfoliation is the earliest and most widely used method for preparing MXene heterojunctions. Its mechanism involves selectively etching the A layer in the MAX phase with HF to exfoliate the MXene material. After purification, the prepared MXene is mixed with other materials (such as graphene oxide and transition metal sulfides) and the MXene heterojunction is prepared through ultrasonic dispersion and hydrothermal reactions.

[0004] However, traditional MXene heterojunction preparation methods often have limitations. Some require hazardous reagents, such as etching with strong acids or bases, while others, such as chemical vapor deposition at temperatures between 700 and 1000°C, present harsh conditions, posing safety risks and potentially negatively impacting the environment. Furthermore, existing preparation methods often require complex equipment and long reaction cycles, resulting in low production efficiency and limited output. Furthermore, some preparation processes suffer from low yields, making them difficult to meet the demands of large-scale applications. These issues not only increase the production cost of MXene heterojunction materials but also hinder their commercialization. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for preparing Mo-based MXene heterojunctions, which is environmentally friendly, has high preparation efficiency and low preparation cost.

[0006] The present invention provides a method for preparing a Mo-based MXene heterojunction, comprising the following steps:

[0007] Under oxygen-free conditions, Mo2Ga2C MAX material, ammonium halide, small molecule intercalant and water are mixed and heated to react, resulting in a Mo-based MXene heterojunction.

[0008] The concentration of the ammonium halide in water is ≥6 mol / L;

[0009] The relative molecular mass of the small molecule intercalant is 40-100, and the concentration of the small molecule intercalant in water is ≥3 mol / L;

[0010] The temperature of the heating reaction is greater than 180°C.

[0011] Preferably, the concentration of the Mo2Ga2C MAX material in water is 5-150 mg / mL.

[0012] Preferably, the ammonium halide is one or more of ammonium fluoride, ammonium chloride, ammonium bromide and ammonium iodide.

[0013] Preferably, the small molecule intercalant is one or more of dimethyl sulfoxide, hydrazine hydrate, ethylenediamine, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile and tetramethylammonium hydroxide.

[0014] Preferably, the concentration of the ammonium halide in water is 6 to 12 mol / L.

[0015] Preferably, the concentration of the small molecule intercalant in water is 3-12 mol / L.

[0016] Preferably, the temperature of the heating reaction is 190-240°C.

[0017] Preferably, the heating reaction time is 24 to 48 hours.

[0018] Preferably, the method further comprises the following steps: after the heating reaction is completed, cooling, washing and drying the obtained reaction product.

[0019] Preferably, the drying method is freeze-drying.

[0020] Compared to the prior art, the present invention provides a method for preparing a Mo-based MXene heterojunction, comprising the following steps: in the absence of oxygen, mixing a Mo2Ga2C2 MAX material, an ammonium halide, a small molecule intercalant, and water, followed by a heating reaction to produce a Mo-based MXene heterojunction; the concentration of the ammonium halide in the water being ≥6 mol / L; the small molecule intercalant having a relative molecular mass of 40 to 100 and a concentration of ≥3 mol / L in the water; and the heating reaction temperature being >180°C. The present invention inventively discovers that a Mo-based MXene heterojunction can be prepared at temperatures >180°C through a hydrothermal reaction of the Mo2Ga2C2 MAX material, ammonium halide, and small molecule intercalant, without following the traditional liquid-phase exfoliation mechanism. The present invention utilizes ammonium halides and small molecule intercalants with improved safety and stability to etch MAX precursors in large quantities in a one-step process and prepare Mo-based MXene heterojunctions. The preparation process is simple, efficient, and low-cost, making it easy to mass-produce. It is safe and reliable, avoiding the use of traditional hazardous reagents such as HF and eliminating the need for the introduction of strong acids or bases. The resulting Mo-based MXene heterojunction has a smooth surface morphology, few defects, and high crystallinity similar to that of Mo2Ga2C. It has application prospects in multiple fields such as energy storage and catalysis, and particularly promotes the practical application of MXene heterojunctions in the field of new energy. The preparation method of Mo-based MXene heterojunctions provided by the present invention is green, efficient, and economical, breaking through the bottleneck of existing technologies and enabling large-scale production and commercial application of MXene heterojunctions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 X-ray diffraction spectra of Mo-based MXene heterojunctions prepared using different small molecule intercalants in Example 1 provided by the present invention;

[0023] Figure 2 This is a scanning electron micrograph of a Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalant in Example 1 provided by the present invention;

[0024] Figure 3 This is a scanning electron micrograph of a Mo-based MXene heterojunction prepared using hydrazine hydrate as a small molecule intercalant in Example 1 provided by the present invention;

[0025] Figure 4This is a scanning electron micrograph of a Mo-based MXene heterojunction prepared using ethylenediamine as a small molecule intercalant in Example 1 provided by the present invention;

[0026] Figure 5 A scanning electron micrograph of a Mo-based MXene heterojunction prepared using N,N-dimethylformamide as a small molecule intercalation agent in Example 1 provided by the present invention;

[0027] Figure 6 A scanning electron micrograph of a Mo-based MXene heterojunction prepared using N-methylpyrrolidone as a small molecule intercalant in Example 1 of the present invention;

[0028] Figure 7 This is a scanning electron micrograph of a Mo-based MXene heterojunction prepared using acetonitrile as a small molecule intercalant in Example 1 provided by the present invention;

[0029] Figure 8 This is a scanning electron micrograph of a Mo-based MXene heterojunction prepared using tetramethylammonium hydroxide as a small molecule intercalant in Example 1 provided by the present invention;

[0030] Figure 9 Scanning electron microscopy-element distribution diagram of the Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalation agent in Example 1 provided by the present invention;

[0031] Figure 10 Energy dispersive X-ray spectrometer image of a Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalation agent in Example 1 provided by the present invention;

[0032] Figure 11 A focused ion beam-high-resolution transmission electron microscopy image of a Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalant in Example 1 of the present invention;

[0033] Figure 12 A high-resolution transmission electron micrograph of a Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalant in Example 1 of the present invention; wherein sub-image A is a bulk Mo2CT x Selected area electron diffraction pattern of , sub-image B is the high-resolution Fourier transform image of amorphous MoS2 grown on the surface;

[0034] Figure 13 The X-ray diffraction spectrum of the Mo-based MXene heterojunction prepared in Example 2 provided by the present invention;

[0035] Figure 14This is a scanning electron microscope image of the Mo-based MXene heterojunction prepared in Example 2 provided by the present invention;

[0036] Figure 15 The X-ray diffraction spectrum of the reaction product prepared in Comparative Example 1 provided by the present invention;

[0037] Figure 16 The X-ray diffraction spectrum of the reaction product prepared in Comparative Example 2 provided by the present invention;

[0038] Figure 17 This is the X-ray diffraction spectrum of the reaction product prepared in Comparative Example 3 provided by the present invention. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The present invention provides a method for preparing a Mo-based MXene heterojunction, comprising the following steps:

[0041] Under oxygen-free conditions, Mo2Ga2C MAX material, ammonium halide, small molecule intercalant and water are mixed and heated to react to obtain Mo-based MXene heterojunction.

[0042] In the preparation method provided by the present invention, the anaerobic condition is preferably achieved by passing argon into the reaction system.

[0043] In the preparation method provided by the present invention, the source of the Mo2Ga2C MAX material is not particularly limited and can be a commercially available product or can be prepared according to the following method:

[0044] Molybdenum carbide nanopowder and metallic gallium are mixed, heated, and ground to obtain a mixture; the mixture is then sintered to obtain the Mo2Ga2C MAX material. The molar ratio of the molybdenum carbide nanopowder to the metallic gallium is preferably 1:(6-12); the sintering pressure is preferably 10-1000 Pa; the sintering temperature is preferably 800-1000°C; and the sintering time is preferably 24-108 hours.

[0045] In the preparation method provided by the present invention, the concentration of the Mo2Ga2C2MAX material in water is preferably 5-150 mg / mL, specifically 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, 90 mg / mL, 100 mg / mL, 110 mg / mL, 120 mg / mL, 130 mg / mL, 140 mg / mL or 150 mg / mL.

[0046] In the preparation method provided by the present invention, the ammonium halide is preferably one or more of ammonium fluoride, ammonium chloride, ammonium bromide and ammonium iodide, more preferably ammonium bromide.

[0047] In the preparation method provided by the present invention, the concentration of the ammonium halide in water is ≥6 mol / L, preferably 6 to 12 mol / L, specifically 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L or 12 mol / L.

[0048] In the preparation method provided by the present invention, the relative molecular mass of the small molecule intercalant is 40-100; the small molecule intercalant is preferably one or more of dimethyl sulfoxide, hydrazine hydrate, ethylenediamine, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile and tetramethylammonium hydroxide.

[0049] In the preparation method provided by the present invention, the concentration of the small molecule intercalant in water is ≥3 mol / L, preferably 3-12 mol / L, specifically 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L or 12 mol / L.

[0050] In the preparation method provided by the present invention, the temperature of the heating reaction is >180°C, preferably 190-240°C, specifically 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C or 240°C.

[0051] In the preparation method provided by the present invention, the heating reaction time is preferably 24 to 48 hours, specifically 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 42 hours, 44 hours, 46 hours or 48 hours.

[0052] The preparation method provided by the present invention preferably further comprises the following steps: after the heating reaction is completed, the obtained reaction product is cooled, washed, and dried. The cooling method is naturally cooling to room temperature; the washing agent is preferably water and / or ethanol; the drying method is preferably freeze-drying; the freeze-drying temperature is preferably -90 to -60°C, specifically -82°C; and the freeze-drying time is preferably 20 to 30 hours, specifically 24 hours.

[0053] The preparation method provided by the present invention utilizes ammonium halides and small molecule intercalants with improved safety and stability to etch MAX precursors in large quantities in a one-step process and prepare Mo-based MXene heterojunctions. The preparation process is simple, efficient, and low-cost, making it easy to mass-produce. It is safe and reliable, avoiding the use of traditional hazardous reagents such as HF and eliminating the need for the introduction of strong acids or bases. The resulting Mo-based MXene heterojunction has a smooth surface morphology, few defects, and high crystallinity similar to that of Mo2Ga2C. It has application prospects in multiple fields such as energy storage and catalysis, and particularly promotes the practical application of MXene heterojunctions in the field of new energy. The preparation method of Mo-based MXene heterojunctions provided by the present invention is green, efficient, and economical, breaking through the bottleneck of existing technologies and enabling large-scale production and commercial application of MXene heterojunctions.

[0054] For the purpose of greater clarity, the present invention is described in detail with reference to the following examples and comparative examples.

[0055] Example 1

[0056] Weigh 200 mg of Mo2Ga2C MAX powder sample, measure 20 mL of deionized water and use an air gun to pass argon to remove dissolved oxygen, add Mo2Ga2C powder to deionized water and pour into 50 mL of para-polyphenylene lining; then, according to the concentration of ammonium bromide in deionized water of 9 mol / L and the concentration of small molecule intercalant in deionized water of 4 mol / L, ammonium bromide and different types of small molecule intercalants (dimethyl sulfoxide, hydrazine hydrate, ethylenediamine, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile, tetramethylammonium hydroxide) are added to the above solution, mixed, stirred and dissolved, and argon is passed through to remove dissolved oxygen; the above para-polyphenylene lining is placed in a stainless steel reactor and placed in a 200°C oven to react for 36 hours; after the reaction, it is naturally cooled to room temperature, repeatedly washed with deionized water and anhydrous ethanol until neutral, and dried at -82°C for 24 hours using freeze-drying technology to obtain a series of Mo-based MXene heterojunctions made with different types of small molecules as intercalants.

[0057] like Figure 1 As shown, Figure 1This is the X-ray diffraction spectrum of the Mo-based MXene heterojunction prepared using different small molecule intercalants in Example 1. It can be seen from the figure that after etching by the above experimental method, the characteristic peaks of Mo2Ga2C at positions such as 34.2°, 37.4°, 40.0° and 42.6° are significantly reduced, proving that Ga is successfully etched out from the interlayer of Mo2Ga2C; the Mo-based MXene heterojunction also shows characteristic peaks different from those of Mo2Ga2C. The (002) at 8.5° is significantly reduced compared to 9.9° of Mo2Ga2C, and the interlayer spacing increases, further proving the success of etching.

[0058] like Figures 2 to 8 As shown, Figures 2 to 8 This is a scanning electron microscope image of the Mo-based MXene heterojunction prepared using different small molecule intercalants in Example 1. It can be seen from the image that the surface morphology of different Mo-based MXene heterojunction materials is unique, with fewer defects and high crystallinity similar to Mo2Ga2C.

[0059] like Figures 9 and 10 As shown, Figures 9 and 10 They are respectively the scanning electron microscope-element distribution diagram and the energy dispersive X-ray spectrometer diagram of the Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalant in Example 1. It can be seen from the figures that the Mo-based MXene heterojunction contains S and a small amount of Br. It is worth mentioning that the atomic ratio content of the Ga element is less than 1%.

[0060] like Figure 11 As shown, Figure 11 This is a focused ion beam-high-resolution transmission electron microscopy image of the Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalation agent in Example 1. It can be seen that the heterojunction part (amorphous molybdenum disulfide) and Mo2CT x There is a clear interface between the bulk phases. Figure 11 The reason why the platinum phase was also observed is that before taking the transmission electron microscope image, a focused ion beam needs to be used to cut the sample, and before cutting the sample, a layer of platinum particles needs to be sprayed on the surface of the sample to increase its conductivity and thus improve its cuttability.

[0061] like Figure 12 As shown, Figure 12 This is a high-resolution transmission electron microscopy image of the Mo-based MXene heterojunction prepared using dimethyl sulfoxide as a small molecule intercalant in Example 1, where sub-image A is the bulk Mo2CT xThe selected area electron diffraction pattern of the surface of the amorphous MoS2 is shown in Figure B. The high-resolution Fourier transform of the surface-grown amorphous MoS2 is shown in Figure A. As can be seen from the figure, the bright spots in Figure A are atoms, which are regularly distributed, proving that it is a hexagonal crystal; while there are no regular bright spots in Figure B, which are amorphous rings. In summary, the Mo2CT of Mo-based MXene heterojunction is x The bulk phase is a hexagonal crystal with good crystallinity, while the heterojunction part is amorphous.

[0062] Example 2

[0063] Weigh 10 g of Mo2Ga2C MAX powder sample, measure 100 mL of deionized water and use an air gun to pass argon to remove dissolved oxygen, add Mo2Ga2C powder to deionized water and pour it into 500 mL of para-polyphenylene lining; then, according to the concentration of ammonium bromide in deionized water of 9 mol / L and the concentration of dimethyl sulfoxide in deionized water of 9 mol / L, add ammonium bromide and dimethyl sulfoxide to the above solution, mix, stir and dissolve, and pass argon to remove dissolved oxygen; place the above para-polyphenylene lining in a stainless steel reactor and put it in a 200°C oven to react for 36 hours; after the reaction, naturally cool to room temperature, repeatedly wash with deionized water and anhydrous ethanol until neutral, and use freeze-drying technology to dry at -82°C for 24 hours to obtain a Mo-based MXene heterojunction.

[0064] like Figure 13 As shown, Figure 13 This is the X-ray diffraction spectrum of the Mo-based MXene heterojunction prepared in Example 2. As can be seen from the figure, the characteristic peak of Mo2Ga2C is significantly reduced after etching, and the (002) in the material is reduced to 8.5° compared to 9.9° of Mo2Ga2C, and the interlayer spacing is increased, further proving the success of the etching.

[0065] like Figure 14 As shown, Figure 14 This is a scanning electron microscope image of the Mo-based MXene heterojunction prepared in Example 2. As can be seen from the figure, the amorphous MoS2 heterojunction is randomly distributed in the bulk Mo2CT x The surface of the bulk phase has a unique surface morphology, few defects, and high crystallinity similar to Mo2Ga2C.

[0066] Comparative Example 1

[0067] Weigh 200 mg of Mo2Ga2C MAX powder sample, measure 20 mL of deionized water and use an air gun to pass argon to remove dissolved oxygen, add Mo2Ga2C powder to deionized water and pour it into 50 mL of para-polyphenylene lining; then, according to the concentration of ammonium bromide in deionized water of 5 mol / L and the concentration of dimethyl sulfoxide in deionized water of 4 mol / L, add ammonium bromide and dimethyl sulfoxide to the above solution, mix, stir and dissolve, and then pass argon to remove dissolved oxygen; the above para-polyphenylene lining is placed in a stainless steel reactor and placed in a 200°C oven to react for 24 hours; after the reaction is completed, naturally cool to room temperature, repeatedly wash with deionized water and anhydrous ethanol until neutral, and use freeze-drying technology to dry at -82°C for 36 hours to obtain the reactant.

[0068] The material obtained in Comparative Example 1 was analyzed using X-ray diffraction technology to obtain its X-ray diffraction pattern, as shown in FIG. Figure 15 As shown, Figure 15 The X-ray diffraction pattern of the reaction product obtained in Comparative Example 1 is shown in FIG. Figure 15 It can be seen that although there is an obvious Mo2CT x The characteristic peaks of MXenes appear, but the characteristic peaks of Mo2Ga2C still exist, proving that Mo2Ga2C is not completely exfoliated and no Mo-based MXene heterojunction is obtained. It can be seen that reducing the ammonium halide concentration during the preparation process will lead to the failure of the preparation of Mo-based MXene heterojunction.

[0069] Comparative Example 2

[0070] Weigh 200 mg of Mo2Ga2C MAX powder sample, measure 20 mL of deionized water and use an air gun to pass argon to remove dissolved oxygen, add Mo2Ga2C powder to deionized water and pour it into 50 mL of para-polyphenylene lining; then, according to the concentration of ammonium bromide in deionized water of 9 mol / L and the concentration of dimethyl sulfoxide in deionized water of 2 mol / L, add ammonium bromide and dimethyl sulfoxide to the above solution, mix, stir and dissolve, and then pass argon to remove dissolved oxygen; the above para-polyphenylene lining is placed in a stainless steel reactor and placed in a 200°C oven to react for 36 hours; after the reaction is completed, naturally cool to room temperature, repeatedly wash with deionized water and anhydrous ethanol until neutral, and use freeze-drying technology to dry at -82°C for 24 hours to obtain the reactant.

[0071] The material obtained in Comparative Example 2 was analyzed using X-ray diffraction technology to obtain its X-ray diffraction pattern, as shown in FIG. Figure 16 As shown, Figure 16 The X-ray diffraction pattern of the reaction product obtained in Comparative Example 2 is shown in FIG. Figure 16As can be seen in the figure, after the etching method described above, the (002) peak shifts to the left, but the characteristic peak of Mo2Ga2C still exists, indicating that the prepared material is not completely etched and no Mo-based MXene heterojunction is obtained. It can be seen that reducing the concentration of small molecule intercalants during the preparation process will lead to the failure of the preparation of Mo-based MXene heterojunctions.

[0072] Comparative Example 3

[0073] Weigh 200 mg of Mo2Ga2C MAX powder sample, measure 20 mL of deionized water and use an air gun to pass argon to remove dissolved oxygen, add Mo2Ga2C powder to deionized water and pour it into 50 mL of para-polyphenylene lining; then, according to the concentration of ammonium bromide in deionized water of 9 mol / L and the concentration of dimethyl sulfoxide in deionized water of 4 mol / L, add ammonium bromide and dimethyl sulfoxide to the above solution, mix, stir and dissolve, and then pass argon to remove dissolved oxygen; the above para-polyphenylene lining is placed in a stainless steel reactor and placed in an oven at 180°C for 36 hours; after the reaction, naturally cool to room temperature, repeatedly wash with deionized water and anhydrous ethanol until neutral, and use freeze-drying technology to dry at -82°C for 24 hours to obtain the reactant.

[0074] The material obtained in Comparative Example 3 was analyzed using X-ray diffraction technology to obtain its X-ray diffraction pattern, as shown in FIG. Figure 17 As shown, Figure 17 The X-ray diffraction pattern of the reaction product obtained in Comparative Example 3 is shown in FIG. Figure 17 It can be seen that after the above etching method, Mo2CT x The (002) peak of Mo2Ga2C is almost absent, and the characteristic peak of Mo2Ga2C still exists, indicating that the prepared material is not completely etched and no Mo-based MXene heterojunction is obtained. It can be seen that lowering the reaction temperature during the preparation process will lead to the failure of the preparation of Mo-based MXene heterojunction.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a Mo-based MXene heterojunction, characterized in that: The following steps are involved: Under oxygen-free conditions, Mo2Ga2C MAX material, ammonium halide, small molecule intercalant and water are mixed and heated to react, resulting in a Mo-based MXene heterojunction. The concentration of the Mo2Ga2C MAX material in water is 10 mg / mL; The ammonium halide is ammonium bromide, and the concentration of the ammonium halide in water is 9 mol / L; The small molecule intercalant is one or more of hydrazine hydrate, ethylenediamine, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile and tetramethylammonium hydroxide, and the concentration of the small molecule intercalant in water is 4 mol / L; The temperature of the heating reaction is 200° C., and the time of the heating reaction is 36 hours.

2. The preparation method according to claim 1, characterized in that The following steps are also included: After the heating reaction is completed, the obtained reaction product is cooled, washed and dried.

3. The preparation method according to claim 2, characterized in that The drying method is freeze drying.

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