Preparation method of self-supporting two-dimensional vacancy doped molybdenum carbide-based supercapacitor flexible electrode

Abstract

MAX-phase Mo2Ga2C is used as a matrix, a liquid phase corrosion method is utilized, the preparation of the two-dimensional vacancy doped molybdenum carbide (Mo2-CTz) nano material is realized through excessive corrosion, and the two-dimensional vacancy doped molybdenum carbide (Mo2-CTz) nano material is applied to the aspect of a hybrid supercapacitor. Compared with other reported MXene materials, the influence of vacancy doping measures on the Mo2CTz nanometer material is studied, the layered MAX ceramic powder is excessively corroded through hydrofluoric acid, vacancies are introduced into a metal layer, vacancy doping of MXene is achieved, and the capacitive performance of the MXene is improved. And vacancy defects are introduced, so that the interlayer spacing of MXene can be increased, activation sites on the surface of the layered structure can be increased, the conductivity of the two-dimensional material can be improved, the utilization rate of pseudocapacitance active sites of the two-dimensional material can be improved, and finally the capacitive performance of the Mo < 2->-CTz-based electrode can be enhanced. The successful development of the two-dimensional vacancy doped Mo < 2->-CTz self-supporting film electrode material lays a foundation for the practical application of electrochemical energy storage devices such as hybrid supercapacitors and ion batteries.

Description

Technical Field

[0001] The present invention belongs to the field of nano functional materials and electrochemical energy storage devices, and particularly relates to a two-dimensional vacancy-doped molybdenum carbide (Mo 2-□ CT z )Nanomaterials, self-supporting supercapacitor flexible electrodes and preparation methods thereof. Background Art

[0002] High power density is essential for advanced batteries due to the demand for fast-charging consumer electronics and electric vehicles. However, high power density and high energy density have been considered to be mutually exclusive device properties. Conventional lithium-ion batteries provide high energy density through lithium-ion intercalation, but their power density and cycle life are poor; supercapacitors achieve high power density (~10kW kg) due to rapid surface ion intercalation and deintercalation. -1 ) and long cycle life (up to 100,000 times or more), but its energy density (5-10Wh·kg -1 ) is much lower than that of lithium-ion batteries. Therefore, combining the advantages of batteries and supercapacitors, developing energy storage devices with high energy density, high power density and long cycle life has become one of the research hotspots of electrochemical energy storage technology.

[0003] Based on this background, hybrid supercapacitors (HICs for short) as a new type of electrochemical energy storage system, combines the advantages of ion batteries and pseudocapacitive supercapacitors, and has the characteristics of good rate performance, high energy density, high output power, long cycle life, safety and environmental protection, and low cost, which can meet the needs of consumer electronics and electric vehicles that require fast charging. However, it is precisely because of the different energy storage mechanisms of the positive and negative electrodes of HICs that the problem of kinetic imbalance has arisen, which greatly limits the further improvement of HICs performance. Therefore, this patent intends to develop a high-performance negative electrode material and its preparation method, so that its devices can operate in a coordinated manner, while having the advantages of high power, fast response, long service life, safety and durability.

[0004] As one of the important components of functional materials, two-dimensional materials have emerged in many physical and chemical fields and play an irreplaceable role. In recent years, two-dimensional transition metal carbides, nitrides and carbonitride layered materials have a two-dimensional structure similar to graphene (Graphene) and are referred to as MXene. MXene has the advantages of unique layered structure, large specific surface area, good conductivity, etc., and is widely used in electrochemical energy storage, biomedicine, photoelectric catalysis, sensors, electromagnetic shielding absorption and many other fields. As one of the new energy storage materials, MXene has been widely studied since its initial discovery. 3 C 2 , which is made of layered ceramic Ti 3 AlC2 The difference in chemical bonds and interlayer forces between compound atoms is obtained by selectively etching the Al layer. MXene has a very wide range of compositions and structures. This is because the precursor MAX itself has a variety of structures, such as M 2 AX, M 3 AX 2 , M 4 AX 3 , as well as various combinations of M-position transition metals, all of which provide theoretical and experimental basis support for the application of MXene-based materials in many fields.

[0005] According to reports, Mo 2 CT x Nanosheets have higher capacity (theoretical and experimental) than most MXenes and have excellent high temperature stability (up to 700°C), but their cycle stability and rate performance are still insufficient. 2 CT x In order to improve the cycling stability and rate performance, people often use defect engineering to design the material structure, improve its physical and chemical properties, and comprehensively improve its electrochemical performance. It is well known that the point-like geometric sites on two-dimensional materials (such as vacancies) can increase the number of active sites to accommodate or interact with more guest ions (such as Li + and Na + ) reaction, thereby increasing the capacity. Among them, vacancy doping can introduce abundant defects, improve the atomic structure, pore structure, micromorphology, surface wettability and other properties of the material, thereby improving the conductivity of the electrode material, expanding the interlayer spacing, achieving rapid ion diffusion and charge transfer, and adding additional Faraday reactions to provide more pseudocapacitance, thereby improving the ion storage capacity of the negative electrode of the hybrid supercapacitor. However, the current research on MXenes in HICs is mainly focused on Ti and V-based MXenes, and there are few reports on the research of Mo-based MXenes, and there are few reports on the research of vacancy doping of Mo-based MXenes. Summary of the invention

[0006] The object of the present invention is to provide a two-dimensional vacancy-doped Mo 2-□ CT z Nanomaterials, hybrid supercapacitor electrodes and preparation methods thereof. Firstly, metal gallium and molybdenum carbide are used as raw materials, and Mo is sintered in atmosphere. 2 Ga 2 C layered ceramic material, and then Mo 2 Ga 2 C layered ceramic powder is used as a precursor, and hydrofluoric acid is used as an etching solution to remove the Ga layer; then, excessive etching is further performed to form abundant metal layer vacancies by using hydrofluoric acid to etch the Mo layer metal, thereby obtaining high-quality vacancy-doped Mo.2-□ CT z Nanomaterials are made into capacitor electrodes through electrode preparation technology and applied in hybrid supercapacitors. The prepared electrode materials show excellent electrochemical properties.

[0007] 1. Two-dimensional vacancy doped Mo 2-□ CT z Nanomaterial and preparation method thereof, comprising the following steps:

[0008] 1.1. Ternary layered Mo 2 Ga 2 Preparation of Ceramic Materials

[0009] 1.1.1. First, follow Mo 2 The molar ratio of C:Ga=1:6-1:10 is obtained by weighing the corresponding raw material powders and preparing 2-10 g of mixed material.

[0010] 1.1.2. Then, the mixture was placed in a 100 mL agate mortar, and ethanol was added and manually ground for 0.5-2 hours to obtain a uniform mixture; the mixture was placed in a corundum crucible and kept at 800-900°C for 36-72 hours under an argon atmosphere, with a heating rate of 5-10°C min -1 .

[0011] 1.1.3. Then, add the sintered mass into 50-200 mL of 8-12 M HCl and stir at room temperature for 12-24 hours.

[0012] 1.1.4. Finally, after centrifugal washing to neutrality, it is dried in an oven at 30-60°C for 12-48 hours to obtain the ternary layered Mo product. 2 Ga 2 C ceramic material.

[0013] 1.2. 2D vacancy-doped Mo 2 CT z Preparation of Nanomaterials

[0014] 1.2.1. Liquid phase etching of Mo using corrosive liquid 2 Ga 2 C to obtain two-dimensional Mo 2-□ CT z Nanomaterials. In a fume hood, take 10-40 mL of 40-50% hydrofluoric acid. Then, weigh 0.5-2 g of the Mo synthesized above. 2 Ga 2 C powder is added to hydrofluoric acid. Then, the mixture is heated to 80-100°C and magnetically stirred at 500-1000 rpm for 3-6 days.

[0015] 1.2.2. After the corrosion reaction is completed, place the mixture in a 50mL centrifuge tube, add an appropriate amount of ultrapure water, centrifuge and wash at 1500-4000 rpm for 2-4 minutes, remove the acidic waste liquid, and repeat several times until the pH of the supernatant is >6; then, place the precipitate in a blue-mouth bottle, add 20-200mL of 25wt.% tetrabutylammonium hydroxide, and stir magnetically at room temperature for 10-30h.

[0016] 1.2.3. After stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 1500-4500rpm for 2-4 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 4000-8000rpm for 2-4 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, with the total volume controlled at 50-200mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic peeling for 0.5-2 hours, and ice bath was added; after the ultrasonication, centrifugation was performed at 1500-3500 rpm for 10-60 minutes, and the suspension was taken; the obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

[0017] 2. Two-dimensional vacancy doped Mo 2-□ CT z A nanomaterial hybrid supercapacitor electrode and a preparation method thereof, characterized in that the electrode comprises the following steps:

[0018] 2.1. Use a pipette to transfer 10-20 mL of 2D Mo 2-□ CT z The suspension is then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) is selected for filtration.

[0019] 2.2. Filtration completes the Mo-containing 2-□ CT z The polypropylene film of the nanosheets was freeze-dried for 2-4 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT z The film is cut into discs with a diameter of 6-16 mm, which is the two-dimensional vacancy-doped Mo 2-□ CT z Thin film electrode.

[0020] 2.3. Weigh the mass of the obtained thin film electrode using a thousandths electronic balance and divide it by the area to obtain the mass of the active material per unit area.

[0021] 3. Two-dimensional vacancy doped Mo 2-□ CT z Hybrid supercapacitor electrode performance test

[0022] 3.1. Three-electrode test system: A thin film electrode with a diameter of 6-12 mm is used as the working electrode; the diameter is 6-12 mm, and the mass per unit area is 25-40 mg cm -2 The activated carbon electrode was used as the counter electrode; the Ag / AgCl electrode was used as the reference electrode. A three-way three-electrode system was assembled with sulfuric acid aqueous solution as the electrolyte, and CV, GCD, EIS and other tests were performed using Shanghai Chenhua CHI660E electrochemical workstation to calculate the electrode specific capacity and rate performance.

[0023] 3.2. Two-electrode test system: A thin film electrode with a diameter of 6-14 mm was used as the negative electrode. Through the capacity and mass ratio, a certain diameter and a unit area mass of 25-40 mg cm -2 The activated carbon electrode was used as the positive electrode, sulfate aqueous solution (lithium, sodium, magnesium, zinc, etc.) or the corresponding organic electrolyte was used as the electrolyte, and a two-electrode system was assembled using a CR2032 button battery shell. Shanghai Chenhua CHI 660E electrochemical workstation and Blue Electric charge and discharge instrument were used to perform CV, GCD, EIS and other performance tests, and the electrode specific capacity, energy density, power density and cycle stability were calculated.

[0024] Beneficial effects of the present invention:

[0025] MAX phase Mo 2 Ga 2 C is used as the matrix, and the two-dimensional vacancy doping Mo is achieved by adjusting the etching time using the liquid phase etching method. 2-□ CT z Preparation of nanomaterials and their application in hybrid supercapacitors. Compared with other reported MXene materials, the research on Mo 2 CT z The vacancy doping measures of nanomaterials use the method of hydrofluoric acid corrosion of MAX layered ceramics to introduce vacancies in the metal layer, realize the vacancy doping of MXene, and improve its electrode performance. The introduction of vacancy defects can increase the MXene interlayer spacing and the activation sites on the surface of the layered structure, which not only improves the conductivity of the material, but also increases the utilization rate of its pseudocapacitive active sites, and ultimately enhances the Mo 2-□ CT z Capacitive performance of two-dimensional vacancy-doped Mo composite electrodes 2-□ CT z The successful development of self-supporting thin film electrode materials will lay the foundation for their further application in other electronic devices such as ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Preparation of two-dimensional vacancy-doped Mo for Example 1 2-□ CT z SEM of nanomaterials.

[0027] Figure 2 Preparation of two-dimensional vacancy-doped Mo for Example 1 2-□ CT z XRD of nanomaterials.

[0028] Figure 3 The two-dimensional vacancy-doped Mo prepared in Example 1 2-□ CT z Cyclic voltammetry curves of nanomaterial electrodes at different scan rates in a three-electrode system.

[0029] Figure 4 The two-dimensional vacancy-doped Mo prepared in Example 1 2-□ CT z Vacancy-doped Mo in nanomaterial electrodes at different scan rates 2-□ CT z Specific capacity of the base electrode. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Embodiment 1:

[0032] 1. Two-dimensional vacancy doped Mo 2-□ CT z Nanomaterial and preparation method thereof, comprising the following steps:

[0033] Step 1: Ternary layered Mo 2 Ga 2 C. Preparation of ceramic materials;

[0034] First, follow Mo 2 The corresponding raw material powders were weighed to prepare 5 g of a mixture with a molar ratio of C:Ga=1:8; then, the mixture was placed in a 100 mL agate mortar, and ethanol was added and manually ground for 1 hour to obtain a uniform mixture; the mixture was placed in a corundum crucible and kept at 850°C for 48 hours under an argon atmosphere, with a heating rate of 8°C min -1 Then, the sintered block was added to 80 mL of 12 M HCl and stirred at room temperature for 12 hours; then, it was centrifuged and washed to neutrality and dried in an oven at 35 ° C for 24 hours to obtain the product, which is the ternary layered Mo 2 Ga 2 C ceramic materials;

[0035] Step 2: 2D vacancy doping with Mo 2-□ CT zPreparation of aqueous solution of nanosheets;

[0036] First, in a fume hood, take 20 mL of 49% hydrofluoric acid. Then, weigh 1 g of the Mo synthesized above. 2 Ga 2 C powder was added to hydrofluoric acid. Then, the mixture was heated to 100°C and magnetically stirred at 600 rpm for 3 days;

[0037] Then, after the corrosion reaction is completed, the mixture is placed in a 50mL centrifuge tube, an appropriate amount of ultrapure water is added, and the mixture is centrifuged at 1500rpm for 2-4 minutes to remove the acidic waste liquid. The process is repeated several times until the pH of the supernatant is >6. Subsequently, the precipitate is placed in a blue-mouth bottle, 50mL of 25wt.% tetrabutylammonium hydroxide is added, and the mixture is magnetically stirred at room temperature for 24h.

[0038] Secondly, after stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 1500rpm for 2 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 6000rpm for 2 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, with the total volume controlled at 100mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic stripping for 1 hour, and then ice bath was added. After the ultrasonic treatment, centrifugation was performed at 3500 rpm for 30 minutes to obtain the suspension. The obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

[0039] The Mo prepared in this example 2 Ga 2 C powder, Mo 2 CT z Nanomaterials and 2D vacancy-doped Mo 2-□ CT z XRD of materials such as Figure 2 As shown in the figure, as the HF etching time increases, Mo 2 Ga 2 Mo in the XRD spectrum of C 2 Ga 2 The diffraction peak of C drops sharply, while the Mo 2-□ CT z The (002) peak gradually increases, which indicates that two-dimensional Mo is successfully prepared under different etching time lines. 2-□ CT z Nanomaterials.

[0040] 2. Two-dimensional vacancy doped Mo 2-□ CTz A supercapacitor electrode and a preparation method thereof, characterized in that the steps include:

[0041] First, use a pipette to transfer 15 mL of 2D Mo 2-□ CT z The suspension was then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) was used for filtration;

[0042] Next, the Mo-containing 2-□ CT z The polypropylene film of the nanosheet was freeze-dried for 3 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT z The film is cut into discs with diameters of 6 and 12 mm, which are two-dimensional vacancy-doped Mo films. 2-□ CT z Thin film electrode.

[0043] Finally, the mass of the obtained thin film electrode is weighed using a thousandths electronic balance and divided by the area to obtain the mass of the active material per unit area.

[0044] The two-dimensional vacancy-doped Mo prepared in this embodiment 2-□ CT z The SEM cross-sectional image of the thin film material is shown in Figure 2 As shown, the results indicate that the free-standing films are formed via the face-to-face stacking of nanosheets.

[0045] 3. Two-dimensional vacancy doped Mo 2-□ CT z Base electrode performance test;

[0046] Three-electrode test system: a thin film electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm and the mass per unit area was 30 mg cm -2 The activated carbon electrode was used as the counter electrode and the Ag / AgCl electrode was used as the reference electrode. 2 SO 4 The solution was an electrolyte to assemble a three-way three-electrode system. Shanghai Chenhua CHI 660E electrochemical workstation was used to perform CV, GCD, EIS and other tests to calculate the electrode specific capacity and rate performance.

[0047] Two-electrode test system: a thin film electrode with a diameter of 12 mm is used as the negative electrode; the diameter is 12 mm, and the mass per unit area is 40 mg cm -2 The activated carbon electrode was used as the positive electrode, and 1M Na 2 SO 4The solution was used as the electrolyte, and a two-electrode system was assembled using a CR2032 button battery shell. Shanghai Chenhua CHI 660E electrochemical workstation and Blue Electric charge and discharge instrument were used to perform CV, GCD, EIS and other performance tests, and the electrode specific capacity, energy density, power density and cycle stability were calculated.

[0048] The two-dimensional vacancy-doped Mo prepared in this embodiment 2-□ CT z CV curves and specific capacity of thin film electrodes are shown in Figure 2. Figure 3 and Figure 4 As shown in Figure 2, at low scan rates, a pair of redox peaks can be observed near -0.1 V and -0.2 V, indicating the contribution of the intercalation / deintercalation mechanism to the capacitance. Figure 4 As shown in the figure, the Mo after pre-modification to form vacancies is calculated through constant current charge and discharge curve. 2-□ CT z The specific capacity of the electrode is 148.19 F g -1 , significantly better than Mo 2 CT z 107.85F g of electrode -1 .

[0049] Embodiment 2:

[0050] 1. Two-dimensional vacancy doped Mo 2-□ CT z Nanomaterial and preparation method thereof, comprising the following steps:

[0051] Step 1: Ternary layered Mo 2 Ga 2 C. Preparation of ceramic materials;

[0052] First, follow Mo 2 The corresponding raw material powders were weighed to prepare 5 g of a mixture with a molar ratio of C:Ga=1:6; then, the mixture was placed in a 100 mL agate mortar, and ethanol was added and manually ground for 1 hour to obtain a uniform mixture; the mixture was placed in a corundum crucible and kept at 850°C for 48 hours under an argon atmosphere, with a heating rate of 8°C min -1 Then, the sintered block was added to 100 mL of 10 M HCl and stirred at room temperature for 12 hours; then, it was centrifuged and washed to neutrality and dried in an oven at 35 ° C for 24 hours to obtain the product, which is the ternary layered Mo 2 Ga 2 C ceramic materials;

[0053] Step 2: 2D vacancy doping with Mo 2-□ CT z Preparation of aqueous solution of nanosheets;

[0054] First, in a fume hood, take 10 mL of 49% hydrofluoric acid. Then, weigh 0.5 g of the Mo synthesized above. 2 Ga 2 C powder was added to hydrofluoric acid. Then, the mixture was heated to 100°C and magnetically stirred at 500 rpm for 3 days;

[0055] Then, after the corrosion reaction is completed, the mixture is placed in a 50mL centrifuge tube, an appropriate amount of ultrapure water is added, and the mixture is centrifuged at 1500rpm for 2 minutes to remove the acidic waste liquid. The process is repeated several times until the pH of the supernatant is >6. Subsequently, the precipitate is placed in a blue-mouth bottle, 25mL of 25wt.% tetrabutylammonium hydroxide is added, and the mixture is magnetically stirred at room temperature for 12h.

[0056] Secondly, after stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 1500rpm for 2 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 4000rpm for 2 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, and control the total volume to 70mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic stripping for 0.5 hours, and then ice bath was added. After the ultrasonic treatment, centrifugation was performed at 1500 rpm for 30 minutes to obtain the suspension. The obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

[0057] 2. Two-dimensional vacancy doped Mo 2-□ CT z A supercapacitor electrode and a preparation method thereof, characterized in that the steps include:

[0058] First, use a pipette to transfer 20 mL of 2D Mo 2-□ CT z The suspension was then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) was used for filtration;

[0059] Next, the Mo-containing 2-□ CT z The polypropylene film of the nanosheet was freeze-dried for 4 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT z The film is cut into discs with diameters of 6 and 12 mm, which are two-dimensional vacancy-doped Mo films. 2-□ CT z Thin film electrode.

[0060] Finally, the mass of the obtained thin film electrode is weighed using a thousandths electronic balance and divided by the area to obtain the mass of the active material per unit area.

[0061] 3. Two-dimensional vacancy doped Mo 2-□ CT z Base electrode performance test;

[0062] Three-electrode test system: a thin film electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm and the mass per unit area was 30 mg cm -2 The activated carbon electrode was used as the counter electrode and the Ag / AgCl electrode was used as the reference electrode. 2 SO 4 The solution was an electrolyte to assemble a three-way three-electrode system. Shanghai Chenhua CHI 660E electrochemical workstation was used to perform CV, GCD, EIS and other tests to calculate the electrode specific capacity and rate performance.

[0063] Two-electrode test system: a thin film electrode with a diameter of 12 mm is used as the negative electrode; the diameter is 12 mm, and the mass per unit area is 40 mg cm -2 The activated carbon electrode was used as the positive electrode, and 1M Na 2 SO 4 The solution was used as the electrolyte, and a two-electrode system was assembled using a CR2032 button battery shell. Shanghai Chenhua CHI 660E electrochemical workstation and Blue Electric charge and discharge instrument were used to perform CV, GCD, EIS and other performance tests, and the electrode specific capacity, energy density, power density and cycle stability were calculated.

[0064] Embodiment 3:

[0065] Step 1: Ternary layered Mo 2 Ga 2 C. Preparation of ceramic materials;

[0066] First, follow Mo 2 The corresponding raw material powders were weighed at a molar ratio of C:Ga=1:10 to prepare 10g of a mixture; then, the mixture was placed in a 100mL agate mortar, and ethanol was added and manually ground for 2 hours to obtain a uniform mixture; the mixture was placed in a corundum crucible and kept at 850°C for 48 hours under an argon atmosphere, with a heating rate of 8°C min -1 Then, the sintered block was added to 160 mL of 12 M HCl and stirred at room temperature for 24 hours; then, it was centrifuged and washed to neutrality and dried in an oven at 35°C for 48 hours to obtain the product, which is the ternary layered Mo 2 Ga 2 C ceramic materials;

[0067] Step 2: 2D vacancy doping with Mo 2-□ CTz Preparation of aqueous solution of nanosheets;

[0068] First, in a fume hood, take 40 mL of 49% hydrofluoric acid. Then, weigh 2 g of the Mo synthesized above. 2 Ga 2 C powder was added to hydrofluoric acid. Then, the mixture was heated to 100°C and magnetically stirred at 800 rpm for 3 days;

[0069] Then, after the corrosion reaction is completed, the mixture is placed in a 50mL centrifuge tube, an appropriate amount of ultrapure water is added, and the mixture is centrifuged at 3500rpm for 3 minutes to remove the acidic waste liquid. The process is repeated several times until the pH of the supernatant is >6. Subsequently, the precipitate is placed in a blue-mouth bottle, 100mL of 25wt.% tetrabutylammonium hydroxide is added, and the mixture is magnetically stirred at room temperature for 24h.

[0070] Secondly, after stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 3500rpm for 2 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 8000rpm for 2 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, with the total volume controlled at 200mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic peeling for 2 hours, and then ice bath was added. After the ultrasonication, centrifugation was performed at 3500 rpm for 30 minutes to obtain the suspension. The obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

[0071] 2. Two-dimensional vacancy doped Mo 2-□ CT z A supercapacitor electrode and a preparation method thereof, characterized in that the steps include:

[0072] First, use a pipette to transfer 10 mL of 2D Mo 2-□ CT z The suspension was then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) was used for filtration;

[0073] Next, the Mo-containing 2-□ CT z The polypropylene film of the nanosheet was freeze-dried for 2 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT z The film is cut into discs with diameters of 6 and 12 mm, which are two-dimensional vacancy-doped Mo films. 2-□CT z Thin film electrode.

[0074] Finally, the mass of the obtained thin film electrode is weighed using a thousandths electronic balance and divided by the area to obtain the mass of the active material per unit area.

[0075] 3. Two-dimensional vacancy doped Mo 2-□ CT z Base electrode performance test;

[0076] Three-electrode test system: a thin film electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm and the mass per unit area was 30 mg cm -2 The activated carbon electrode was used as the counter electrode and the Ag / AgCl electrode was used as the reference electrode. 2 SO 4 The solution is an electrolyte to assemble a three-way three-electrode system. Shanghai Chenhua CHI660E electrochemical workstation is used to perform CV, GCD, EIS and other tests to calculate the electrode specific capacity and rate performance.

[0077] Two-electrode test system: a thin film electrode with a diameter of 12 mm is used as the negative electrode; the diameter is 12 mm, and the mass per unit area is 40 mg cm -2 The activated carbon electrode was used as the positive electrode, and 1M Na 2 SO 4 The solution was used as the electrolyte, and a two-electrode system was assembled using a CR2032 button battery shell. Shanghai Chenhua CHI 660E electrochemical workstation and Blue Electric charge and discharge instrument were used to perform CV, GCD, EIS and other performance tests, and the electrode specific capacity, energy density, power density and cycle stability were calculated.

[0078] Embodiment 4:

[0079] Step 1: Ternary layered Mo 2 Ga 2 C. Preparation of ceramic materials;

[0080] First, follow Mo 2 The corresponding raw material powders were weighed to prepare 10 g of a mixture with a molar ratio of C:Ga=1:8; then, the mixture was placed in a 100 mL agate mortar, and ethanol was added and manually ground for 2 hours to obtain a uniform mixture; the mixture was placed in a corundum crucible and kept at 850°C for 48 hours under an argon atmosphere, with a heating rate of 8°C min -1 Then, the sintered block was added to 160 mL of 12 M HCl and stirred at room temperature for 24 hours; then, it was centrifuged and washed to neutrality and dried in an oven at 35 ° C for 48 hours to obtain the product, which is the ternary layered Mo 2 Ga 2 C ceramic materials;

[0081] Step 2: 2D vacancy doping with Mo 2-□ CT z Preparation of aqueous solution of nanosheets;

[0082] First, in a fume hood, take 20 mL of 49% hydrofluoric acid. Then, weigh 1 g of the Mo synthesized above. 2 Ga 2 C powder was added to hydrofluoric acid. Then, the mixture was heated to 100°C and magnetically stirred at 600 rpm for 3 days;

[0083] Then, after the corrosion reaction is completed, the mixture is placed in a 50mL centrifuge tube, an appropriate amount of ultrapure water is added, and the mixture is centrifuged at 3500rpm for 2 minutes to remove the acidic waste liquid. The process is repeated several times until the pH of the supernatant is >6. Subsequently, the precipitate is placed in a blue-mouth bottle, 50mL of 25wt.% tetrabutylammonium hydroxide is added, and the mixture is magnetically stirred at room temperature for 20 hours.

[0084] Secondly, after stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 3500rpm for 2 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 6000rpm for 2 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, and control the total volume to 150mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic peeling for 1.5 hours, and then ice bath was added. After the ultrasonication, centrifugation was performed at 3500 rpm for 30 minutes to obtain the suspension. The obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

[0085] 2. Two-dimensional vacancy doped Mo 2-□ CT z A supercapacitor electrode and a preparation method thereof, characterized in that the steps include:

[0086] First, use a pipette to transfer 15 mL of 2D Mo 2-□ CT z The suspension was then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) was used for filtration;

[0087] Next, the Mo-containing 2-□ CT z The polypropylene film of the nanosheet was freeze-dried for 3 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT zThe film is cut into discs with diameters of 6 and 12 mm, which are two-dimensional vacancy-doped Mo films. 2-□ CT z Thin film electrode.

[0088] Finally, the mass of the obtained thin film electrode is weighed using a thousandths electronic balance and divided by the area to obtain the mass of the active material per unit area.

[0089] 3. Two-dimensional vacancy doped Mo 2-□ CT z Base electrode performance test;

[0090] Three-electrode test system: a thin film electrode with a diameter of 6 mm was used as the working electrode; the diameter was 6 mm and the mass per unit area was 30 mg cm -2 The activated carbon electrode was used as the counter electrode and the Ag / AgCl electrode was used as the reference electrode. 2 SO 4 The solution was an electrolyte to assemble a three-way three-electrode system. Shanghai Chenhua CHI 660E electrochemical workstation was used to perform CV, GCD, EIS and other tests to calculate the electrode specific capacity and rate performance.

[0091] Two-electrode test system: a thin film electrode with a diameter of 12 mm is used as the negative electrode; the diameter is 12 mm, and the mass per unit area is 40 mg cm -2 The activated carbon electrode was used as the positive electrode, and 1M Na 2 SO 4 The solution was used as the electrolyte, and a two-electrode system was assembled using a CR2032 button battery shell. Shanghai Chenhua CHI 660E electrochemical workstation and Blue Electric charge and discharge instrument were used to perform CV, GCD, EIS and other performance tests, and the electrode specific capacity, energy density, power density and cycle stability were calculated.

Claims

1. Two-dimensional vacancy doped molybdenum carbide (Mo 2-□ CT z ) A method for preparing a nano material, characterized in that: The following steps are involved: Step 1: Preparation of ternary layered Mo2Ga2C ceramic material; First, weigh the corresponding raw material powder according to the molar ratio of Mo2C:Ga=1:6-1:10 to prepare 2-10g of mixed material; then, place the mixed material in a 100mL agate mortar and grind it manually for 0.5-2 hours to obtain a uniform mixed material; place the mixed material in a corundum crucible and keep it at 800-900℃ for 36-72 hours under argon atmosphere, with a heating rate of 5-10℃min -1 ; Then, the sintered block is added to 50-200 mL of 8-12M HCl and stirred at room temperature for 12-24 hours; then, it is centrifuged and washed to neutrality and then dried in an oven at 30-60°C for 12-48 hours to obtain a ternary layered Mo2Ga2C ceramic material; Step 2: 2D vacancy doping with Mo 2-□ CT z Preparation of aqueous solution of nanosheets; First, in a fume hood, take 10-40 mL of hydrofluoric acid with a mass concentration of 40-50%. Then, weigh 0.5-2 g of the Mo2Ga2C powder synthesized above and add it to the hydrofluoric acid. Then, heat the mixture to 80-100° C. and stir it magnetically at a speed of 500-1000 rpm for 3-6 days; Then, after the corrosion reaction is completed, the mixture is placed in a 50mL centrifuge tube, an appropriate amount of ultrapure water is added, and the mixture is centrifuged at 1500-4000rpm for 2-4 minutes to remove the acidic waste liquid, and the process is repeated several times until the pH of the supernatant is >6; then, the precipitate is placed in a blue-mouth bottle, 20-200mL of 25wt.% tetrabutylammonium hydroxide is added, and the mixture is magnetically stirred at room temperature for 10-30h. Secondly, after stirring, place the mixture in a 50mL centrifuge tube, wash the excess tetrabutylammonium hydroxide with ethanol, centrifuge at 1500-4500rpm for 2-4 minutes, repeat several times until the pH of the supernatant is less than 8; add an appropriate amount of ultrapure water, centrifuge at 4000-8000rpm for 2-4 minutes to remove ethanol. Add ultrapure water and place the black precipitate obtained by centrifugation in a 250mL blue-mouth bottle, with the total volume controlled at 50-200mL. Pass 20mL·min into the mixed liquid. -1 Argon gas was used, and ultrasonic cell crusher was used for ultrasonic peeling for 0.5-2 hours, and ice bath was added; after the ultrasonication, centrifugation was performed at 1500-3500 rpm for 10-60 minutes, and the suspension was taken; the obtained suspension was a few-layer two-dimensional vacancy-doped Mo 2-□ CT z Nanosheet aqueous solution.

2. 2D vacancy doped Mo 2-□ CT z A supercapacitor electrode and a preparation method thereof, characterized in that the steps include: First, use a pipette to transfer 10-20 mL of 2D Mo 2-□ CT z The suspension was then formed into a membrane using a vacuum filtration device, and a nanoporous polypropylene membrane (Celgard3501, 0.064 μm pore size) was used for filtration; Next, the Mo-containing 2-□ CT z The polypropylene film of the nanosheets was freeze-dried for 2-4 hours, and the self-supporting two-dimensional vacancy-doped Mo attached to the polypropylene film was peeled off after drying. 2-□ CT z The film is cut into discs with a diameter of 6-16 mm, which is the two-dimensional vacancy-doped Mo 2-□ CT z Thin film electrode. Finally, the mass of the obtained thin film electrode is weighed using a thousandths electronic balance and divided by the area to obtain the mass of the active material per unit area.

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