CN111755685A - A kind of MXene two-dimensional material and its preparation method and application - Google Patents

Abstract

The invention discloses a two-dimensional MXene material, which belongs to the field of materials, and comprises a MXene precursor and a reaction deposition solution, wherein the reaction deposition solution is a mixed solution of fluorine salt and boric acid, and the fluorine salt includes ammonium fluoride, ammonium hydrogen fluoride and ammonium hydrogen fluoride. and one or more of metal fluoride salts, the molar ratio of fluoride salt and boric acid in the mixed solution is 0.01-0.3:0.02-1.5, and the MXene precursor includes Ti ₃ AlC ₂ , Ti ₂ AlC, Any one or a combination of two or more of V ₂ AlC, Mo ₂ AlC and Nb ₂ AlC. One MXene two-dimensional material of the present invention uses fluorine salt and boric acid as the reaction deposition solution, the reaction is mild and easy to control, and the prepared MXene two-dimensional material has larger interlayer spacing and larger specific surface area. The invention also discloses A preparation method of MXene two-dimensional material and application in preparing electrodes.

Description

A kind of MXene two-dimensional material and its preparation method and application

technical field

The invention relates to the field of materials, in particular to a two-dimensional MXene material and a preparation method and application thereof.

Background technique

MXene, a new type of graphene-like two-dimensional nanomaterials, has unique advantages such as high specific surface area, excellent electronic conductivity and abundant surface hydrophilic functional groups. The application fields show great potential: (1) MXene surface contains a large amount of -OH and -O, which can establish strong correlation with various semiconductor surfaces; (2) excellent electrical conductivity contributes to the high efficiency of photogenerated charge-carriers Transfer; (3) Good hydrophilicity ensures full contact with the aqueous solution and stable existence.

Since 2011, the group of Michel Barsoum, a professor at Drexel University in the United States, first used hydrofluoric acid (HF) to etch the bulk material (MAX) to peel off the weakly bound Al atomic layer in MAX to obtain tightly bound Mn _+1. X _n T _x sheet composites, T represents the surface functional group (-O, -OH, or -F), because its physicochemical properties are analogous to graphene, the resulting sheet is named MXene. Subsequently, MXenes as a new class of two-dimensional materials have aroused great interest among researchers and received extensive attention.

However, most of the currently synthesized MXenes are multi-layer two-dimensional structures with small interlayer spacing. To obtain MXene materials with few or single layers, increased interlayer spacing and tunable, further layered exfoliation is very necessary and is the current MXene as a material. Research hotspots and challenges in the application field of electrode materials. At present, the most common method for preparing MXene is to chemically etch and lift off the MAX phase using a high concentration of HF or a mixture of lithium fluoride and hydrochloric acid (LiF+HCl). It is worth noting that HF and HCl are highly corrosive and toxic, and have greater dangers during the experimental operation. Therefore, it can be seen that the existing methods for synthesizing MXene mainly have the following disadvantages: (1) the etching solution is highly toxic and corrosive, and has great danger and is not environmentally friendly; (2) the reaction speed of the synthesis process is slow and usually takes a long time In addition, it is difficult to control, and the cost is high; (3) The synthesized MXene usually contains terminal functional groups such as F-, which adversely affects its performance as an electrode and its composite material.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide an MXene two-dimensional material.

The technical solution of the present invention is as follows:

An MXene two-dimensional material, an MXene precursor and a reaction deposition solution, wherein the reaction deposition solution is a mixed solution of fluorine salt and boric acid.

Preferably, the fluoride salt includes one or more of ammonium fluoride, ammonium hydrogen fluoride and metal fluoride salts.

Preferably, the molar ratio of fluorine salt and boric acid in the mixed solution is 0.01-0.3:0.02-1.5.

Preferably, the MXene precursor includes any one or a combination of two or more of Ti ₃ AlC ₂ , Ti ₂ AlC, V ₂ AlC, Mo ₂ AlC and Nb ₂ AlC.

Another object of the present invention is to provide: a preparation method of MXene two-dimensional material, comprising the following steps:

Step 1: prepare the reaction deposition solution of fluorine-containing salt and boric acid;

Step 2: place the MXene precursor in the reaction deposition solution in Step 1 to perform a hydrothermal reaction to obtain a suspension;

Step 3: centrifuging the suspension in Step 2, taking the suspension, washing it to neutrality, and drying to obtain the MXene two-dimensional material.

Preferably, in the second step, ultrasonic treatment is performed simultaneously with the hydrothermal reaction.

Preferably, in the second step, the reaction temperature of the hydrothermal reaction is 90-180° C., and the reaction time is 1-12 h.

Preferably, in the second step, the hydrothermal reaction adopts a hydrothermal reaction kettle made of polyvinyl fluoride.

Preferably, in the third step, the specific drying process is as follows: vacuum drying is adopted, and the drying temperature is 60-90°C.

The invention also discloses the application of an MXene two-dimensional material in preparing electrodes.

The present invention has at least one of the following beneficial effects:

(1) An MXene two-dimensional material of the present invention uses fluorine salt and boric acid as the reaction deposition solution, the reaction is mild and easy to control, and the prepared MXene two-dimensional material has a large interlayer spacing and a large specific surface area.

(2) The preparation method of a MXene two-dimensional material of the present invention adopts a hydrothermal reaction, which can greatly shorten the time of the synthesis reaction.

(3) The application of an MXene two-dimensional material of the present invention in preparing an electrode can directly add a base material during a hydrothermal reaction, thereby preparing an electrode, avoiding the disadvantage of using a binder for the electrode material in the traditional method, The preparation process of the electrode is greatly saved, and the influence of the binder on the electrochemical performance is avoided.

Description of drawings

Fig. 1 is the XRD pattern of embodiment 2;

Fig. 2 is the SEM image of embodiment 1-3 and the TEM image of embodiment 2;

Figure 3 is the CV curve of the electrode at different temperatures;

Fig. 4 is the electrode CV curve that embodiment 2 makes under different scanning speeds;

Fig. 5 is the constant current charge-discharge curve of the electrode that embodiment 1-3 makes under constant current density;

FIG. 6 is the constant current charge-discharge curve of the electrode prepared in Example 2 under different current densities.

Detailed ways

In order to make the content, technical solutions and advantages of the present invention clearer, the present invention will be further described below with reference to specific embodiments and accompanying drawings. These embodiments are only used to illustrate the present invention, and the present invention is not limited to the following embodiments.

An MXene two-dimensional material, the reaction raw material includes MXene precursor and a reaction deposition solution, the reaction deposition solution is a mixed solution of fluorine salt and boric acid.

The fluoride salt includes one or more of ammonium fluoride, ammonium hydrogen fluoride and metal fluoride salt, wherein the metal fluoride salt may be (NH ₄ ) ₂ TiF ₆ or TiF ₄ .

The molar ratio of fluorine salt and boric acid in the mixed solution is 0.01-0.3:0.02-1.5.

The MXene precursor includes any one or a combination of two or more of Ti ₃ AlC ₂ , Ti ₂ AlC, V ₂ AlC, Mo ₂ AlC and Nb ₂ AlC.

A preparation method of MXene two-dimensional material, comprising the following steps:

Step 1: prepare the reaction deposition solution of fluorine-containing salt and boric acid;

Step 2: place the MXene precursor in the reaction deposition solution in Step 1 to perform a hydrothermal reaction to obtain a suspension;

Step 3: Centrifuge the suspension in Step 2, take the suspension, wash it to neutrality, and dry to obtain the MXene two-dimensional material, wherein the washing can be alternately washed with deionized water and ethanol.

In the second step, ultrasonic treatment is performed simultaneously with the hydrothermal reaction, and specifically, the ultrasonic treatment time is 1-3h.

In the second step, the reaction temperature of the hydrothermal reaction is 90-180° C., and the reaction time is 1-12 h.

In the second step, the hydrothermal reaction adopts a hydrothermal reaction kettle made of polyvinyl fluoride, and the high temperature and high pressure container made of polytetrafluoroethylene is very suitable for the hydrothermal reaction of the present invention, and does not bring pollution sources, which can ensure Minimize the impact on the process of synthesizing MXene 2D materials.

In the step 3, the specific drying process is as follows: vacuum drying is adopted, and the drying temperature is 60-90 °C, preferably 80 °C, which is a moderate drying temperature, which can not only dry the material well, but will not cause any damage to its physicochemical properties. obvious impact.

The drying time is preferably 24 hours, the prepared material has a large specific surface area, and the surface adsorbs more water, and the drying time is longer, and the water can be dehydrated.

The present invention also provides an application of MXene two-dimensional material in preparing electrodes, which may specifically include the following steps:

S1: prepare a reaction deposition solution of fluorine-containing salt and boric acid;

S2: place the MXene precursor and the substrate in the reaction deposition solution in step S1 to perform a hydrothermal reaction to obtain a prefabricated electrode, wherein the substrate can be a nickel foam current collector or other current collectors, not limited to this;

S3: centrifuging and washing the electrode in step S2 until neutral, and drying to obtain an electrode.

The technical solutions of the present invention will be further explained in detail below with reference to several preferred embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.

illustrate:

In Figure 3, hl-110, hl-130, and hl-150 are respectively the sample numbers of the following Examples 1-3;

hl-110, hl-130, and hl-150 in Figure 5 are the electrode sample numbers prepared in the following Examples 1-3, respectively;

为长度单位埃，1埃＝1×10^-10米，CV为循环伏安法，GCD为恒流充放电。mentioned in the following examples

Angstrom is the unit of length, 1 Angstrom=1×10 ^-10 meters, CV is cyclic voltammetry, and GCD is constant current charge and discharge.

Example 1

Dispose 0.03mol/L (NH ₄ ) ₂ TiF ₆ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to prepare a reaction deposition solution, weigh 0.02g Ti ₃ AlC ₂ and add it into the reaction deposition solution, The reaction deposition solution was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was placed in an oven for synthesis reaction at 110 °C for 3 hours. After the reaction, the obtained suspension was centrifuged, the lower layer of suspension was taken out, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80° C. for 24 hours to obtain Ti ₃ C ₂ - MXene/TiO ₂ powder material.

Example 2

Dispose 0.03mol/L (NH ₄ ) ₂ TiF ₆ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to prepare a reaction deposition solution, weigh 0.02g Ti ₃ AlC ₂ and add it into the reaction deposition solution, The reaction deposition solution was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was placed in an oven for synthesis reaction at 130 °C for 3 hours. After the reaction, the obtained suspension was centrifuged, the lower layer of suspension was taken out, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80° C. for 24 hours to obtain Ti ₃ C ₂ - MXene/TiO ₂ powder material.

Example 3

Dispose 0.03mol/L (NH ₄ ) ₂ TiF ₆ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to prepare a reaction deposition solution, weigh 0.02g Ti ₃ AlC ₂ and add it into the reaction deposition solution, The reaction deposition solution was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was placed in an oven for synthesis reaction at 150 °C for 3 hours. After the reaction, the obtained suspension was centrifuged, the lower layer of suspension was taken out, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80° C. for 24 hours to obtain Ti ₃ C ₂ - MXene/TiO ₂ powder material.

Example 4

Dispose 0.03mol/L NH ₄ HF ₂ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to make a reaction deposition solution, weigh 0.02g Ti ₃ AlC ₂ and add it to the reaction deposition solution, and the reaction deposition solution is prepared. The liquid was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was placed in an oven for synthesis reaction at 130 °C for 3 hours. After the reaction, the obtained suspension was centrifuged, the lower layer of suspension was taken out, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80° C. for 24 hours to obtain Ti ₃ C ₂ - MXene powder material.

Example 5

Dispose 0.03mol/L (NH ₄ ) ₂ TiF ₆ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to prepare a reaction deposition solution, weigh 0.02 g of Ti ₂ AlC and add it to the reaction deposition solution. The reaction deposition solution was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was put into an oven for synthesis reaction at 130°C for 3 hours. After the reaction, the obtained suspension was centrifuged, the lower layer of suspension was removed, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80 °C for 24 h to obtain Ti ₂ C-MXene /TiO ₂ powder material.

Example 6

Dispose 0.03mol/L (NH ₄ ) ₂ TiF ₆ solution and 0.09 mol/L H ₃ BO ₃ solution respectively, stir and mix with magnetic force to prepare a reaction deposition solution, weigh 0.02 g of V ₂ AlC and add it to the reaction deposition solution. The reaction deposition solution was placed in a 100 mL hydrothermal reactor, and then the hydrothermal reactor was put into an oven for synthesis reaction at 130°C for 3 hours. After the reaction, the obtained suspension was centrifuged, and the lower layer of suspension was removed, washed alternately with deionized water and ethanol until neutral, and then the obtained solid was vacuum-dried at 80 °C for 24 h to obtain V ₂ C-MXene. /TiO ₂ powder material.

Comparative Example 1

In a fume hood, a 5wt.% HF solution was prepared, and 0.5 g of Ti ₃ AlC ₂ precursor material was weighed and slowly added to it, and the reaction was conducted under magnetic stirring at room temperature for 30h. After the reaction, the obtained suspension was centrifuged, and the lower layer of suspension was removed. In order to remove strong acid impurities, the suspension must be repeatedly washed with deionized water and ethanol ultrasonically for 7 times to neutrality, in order to obtain MXene with increased interlayer spacing. , it is necessary to add organic macromolecular dimethyl sulfoxide (DMSO) to intercalate MXene again under ultrasonic state, and then vacuum dry the obtained solid at 80 °C for 24 h to obtain Ti ₃ C ₂ -MXene powder material.

Comparative Example 2

In a fume hood, a mixed solution of 5 mol/L LiF and 6 mol/L HCl was prepared, and 0.5 g of Ti ₃ AlC ₂ precursor material was weighed and slowly added to it, and the reaction was carried out with magnetic stirring at room temperature for 30 hours. After the reaction, the obtained suspension was centrifuged, and the suspension in the lower layer was removed. In order to remove strong acid impurities, the suspension must be repeatedly washed with deionized water and ethanol ultrasonically for 6 times to neutrality. In order to obtain MXene with increased interlayer spacing, It needs to be degraded again in ultrasonic state for 12h to maintain the Li ⁺ intercalated MXene, and then the obtained solid is vacuum-dried at 80°C for 24h to obtain Ti ₃ C ₂ -MXene powder material.

References for the preparation methods of comparative examples 1 and 2: Alhabeb M, Maleski K, Anasori B, et al. Guidelines for synthesis and processing of two-dimensional titaniumcarbide (Ti ₃ C ₂ T _x MXene) [J]. Chemistry of Materials, 2017 , 29(18):7633-7644.

The sample of Example 2 is tested by XRD pattern, as shown in Figure 1, the sharp diffraction peaks show that the crystallinity of the sample material is very good. The diffraction peaks of the sample appear at diffraction angles of 25.3°, 37.6°, 48.1°, 53.9°, and 63°, corresponding to (101), (004), (200), (105) of the anatase TiO ₂ crystal phase, respectively. , (204) crystal plane, and other peaks are also in one-to-one correspondence with the standard anatase PDF card (JCPDS 21-1272), indicating that the prepared sample contains anatase phase TiO ₂ . The diffraction characteristic peaks around 7.1°, 28.6° and 42.3° correspond to the (002), (006) and (008) crystal planes of Ti ₃ C ₂ -MXene, respectively, and there is no bulk material Ti in the pattern. The diffraction peaks of ₃ AlC ₂ indicate that the method of the present invention successfully peels off the Al layer in Ti ₃ AlC ₂ to obtain a Ti ₃ C ₂ -MXene/TiO ₂ composite material.

和

对比例1和2的层间距为

和

经比表面积测试(比表面积是通过氮气吸脱附仪测试得到)，实施例1-6试样的比表面积分别为15、20、25、25、25、25m²/g，对比例1和2的比表面积为11和12m²/g，这种开放式的层状结构有利于电极材料的电化学性能。同时，图2d为少层MXene的TEM图，并从该图中能看出MXene成功剥离分层且层间距增大，进一步证明了本发明方法的可行性。At the same time, Example 1-3 was tested by SEM and Example 2 by TEM, as shown in Figure 2. It can be seen from Figure 2 that the composite material of Example 1-3 has a larger interlayer spacing, and Figure 2b is synthesized at 130 °C. The MXene/TiO ₂ composites presented a layered structure with increased interlayer spacing, while the interlayer spacings of the composites of Examples 1-6 were tested as

and

The interlayer spacing of Comparative Examples 1 and 2 is

and

After the specific surface area test (the specific surface area is obtained by the nitrogen adsorption and desorption instrument), the specific surface areas of the samples of Examples 1-6 are 15, 20, 25, 25, 25, 25m ² /g, respectively, and Comparative Examples 1 and 2 The specific surface area of 11 and 12 m ² /g, this open layered structure is beneficial to the electrochemical performance of the electrode material. Meanwhile, Figure 2d is the TEM image of the few-layer MXene, and it can be seen from this figure that the MXene is successfully delaminated and the interlayer spacing is increased, which further proves the feasibility of the method of the present invention.

The etching principle of embodiment 1-3 is as follows:

[BO ₃ ] ^3- +4F ^- +6H ⁺ →[BF ₄ ] ^- +3H ₂ O

Ti ₃ AlC ₂ +3F ^- +3H ⁺ →Ti ₃ C ₂ +AlF ₃ +1.5H ₂

Ti ₃ C ₂ +2H ₂ O→Ti ₃ C ₂ (OH) ₂ +H ₂

Ti ₃ C ₂ +2F ^- +2H ⁺ →Ti ₃ C ₂ F ₂ +H ₂

Ti-OH+OH-Ti→Ti-O-Ti+H ₂ O

According to the principle of the liquid deposition reaction between fluorine salt and boric acid, the fluorine salt undergoes a hydrolysis reaction in the solution to generate an F ^- containing solution, and boric acid acts as an F ^- trapping agent to further promote the hydrolysis reaction ^. The Al layer in the MXene precursor has an etching effect, and then a layered MXene material is obtained. At the same time, the precursor solution generated in situ by the hydrolysis reaction is combined with Ti ₃ C ₂ through the F ^- end group, so that the in situ reaction occurs to form the interlayer spacing. Enlarged layered structure of Mxene 2D materials.

Comparative example 1 is the preparation method adopted in the prior art. From the test values of interlayer spacing and specific surface area, it can be known that the test values of comparative examples 1 and 2 are both smaller than the test values of Examples 1-6. It can be seen that the preparation method adopted in the present invention can obtain Larger layer spacing and higher specific surface area, and, from the point of view of the preparation method, the corrosive HF or LiF+HCl solution first used in Comparative Examples 1 and 2 is more dangerous and not conducive to environmental protection. , the synthesis time is as long as 30h, and the synthesis speed is slow.

The MXene materials synthesized in Comparative Examples 1 and 2 contain F ^- terminal functional groups, and the F ^- terminal group is generally less active and will mask the active sites with higher electrochemical activity, making it difficult to expose, that is, affecting the MXene. However, in the present invention, the precursor solution generated in situ by the hydrolysis reaction is combined with Ti ₃ C ₂ through the F ^- end group, which consumes and reduces the end-group functional group and avoids the drawbacks in Comparative Examples 1 and 2. .

At the same time, in the preparation process of the above-mentioned embodiment, a substrate such as foam nickel (NF) current collector is added into the hydrothermal reaction kettle, and the other steps are the same as those of the embodiment, so as to obtain an electrode, and the electrode prepared by each embodiment is electrochemically carried out. The performance test is cyclic voltammetry test and constant current charge-discharge test respectively. The test values are shown in Figure 3-6.

It can be seen from Figure 3 and Figure 4 that Figure 3 is the CV curve of the electrode under different reaction temperature conditions, and the scan rate is 10mV/s. It can be seen from Figure 3 that there are corresponding redox peaks in the CV curve. As the reaction temperature increases, the areas of the oxidation peak and the reduction peak increase accordingly, and maintain good symmetry, which indicates that the MXene two-dimensional material The prepared electrodes have good reversibility and low impedance conductivity.

Figure 4 shows the CV curves of the electrode samples prepared in Example 2 at different scanning speeds. As the scanning speed increases from 2mV/s to 200mV/s, the oxidation peak gradually shifts to the right, and the reduction peak shifts to the left at the same time. The potential difference also increases gradually, especially when the scan rate is greater than 50mV/s, that is, no obvious oxidation peak is observed at the scan rate of 100mV/s and 200mV/s. The main reason for this is that at a large scanning speed, the diffusion of current in the electrolyte is hindered, the equivalent internal resistance increases, and the active material on the electrode surface produces an electrochemical polarization phenomenon, thus affect the progress of the electrochemical reaction. However, the shape of the curve remains basically stable, and there is no large offset, indicating the good conductivity of the sample electrode.

It can be seen from FIG. 5 and FIG. 6 that FIG. 5 is the constant current charge-discharge (GCD) curve of the electrodes prepared in Examples 1-3. The set current density is 1A/g, and within the voltage window range of 0-0.6V corresponding to the CV test, it can be seen from Figure 5 that the current and time are not linearly related, but between 0.3V and 0.4V There is an obvious discharge plateau between them, showing similar electrochemical performance to the battery material. Among them, the electrode sample prepared in Example 2 showed the largest discharge time, and the curves of Examples 1 and 3 appeared to have overlapping discharge times lower than that of the electrode sample prepared in Example 2, which was mainly due to the fact that the reaction temperature was 130 °C for synthesis The MXene 2D material, through the intercalation of in-situ deposited _TiO2 , has a more open layered microstructure (see Fig. 2b), this highly open layered structure, when used as an electrode, will allow more The exposure of the active sites to the liquid electrolyte will also promote higher ion and electron transport efficiency. Therefore, its electrochemical performance is significantly improved.

Figure 6 is the GCD curve of the electrode samples prepared in Example 2 under different current densities. It can be seen from the figure that with the increase of the current density, the entire charge and discharge time decreases correspondingly, and the specific capacitance value corresponding to the electrode gradually decreases. This is because the intercalation and outflow of protons are carried out between the electrolyte and the electrode during the electrochemical reaction, but the exchange process of protons is slow, and under large discharge currents, the protons inside the electrolyte will be excessively lost or excessive. The saturation situation affects the redox reaction, resulting in an increase in the resistivity in the equivalent circuit, thereby reducing the specific capacitance. However, the sample electrode still maintains the nonlinear characteristic shape of the charge-discharge curve even at a high current density, and exhibits good rate performance. The reason for this phenomenon is mainly due to the more open layer of the MXene 2D material. The spacing structure can fully expose and contact more active sites in aqueous electrolytes, thereby promoting higher proton transport efficiency.

Therefore, it can be seen that the electrode with no binder structure prepared by the present invention will greatly reduce the contact resistance of the interface between the conductive substrate and the electrode and the internal resistance caused by the binder itself, and at the same time, due to the prepared electrode The material has an open layered structure, more acceptable adsorption of electrolyte ions and a higher specific surface area. Therefore, it has great application prospects in improving the electrochemical performance of electrode materials.

Under the premise of no conflict, those skilled in the art can freely combine and superimpose the above additional technical features.

In the description of the embodiments of the present invention, it should be understood that "-" and "-" represent a range between two numerical values, and the range includes the endpoints. For example: "A-B" means a range greater than or equal to A and less than or equal to B. "A to B" represents a range greater than or equal to A and less than or equal to B.

In the description of the embodiments of the present invention, the term "and/or" herein is only an association relationship to describe the associated objects, indicating that there may be three kinds of relationships, for example, A and/or B, may indicate that: exist independently A, there are both A and B, and there are three cases of B alone. In addition, the character "/" in this text generally indicates that the related objects are an "or" relationship.

The above descriptions are only the preferred embodiments of the present invention, as long as the technical solutions that achieve the purpose of the present invention by basically the same means fall within the protection scope of the present invention.

Claims (10)

1. An MXene two-dimensional material, characterized by: the reaction raw materials comprise MXene precursor and reaction deposition liquid, wherein the reaction deposition liquid is a mixed solution of villiaumite and boric acid.

2. An MXene two-dimensional material according to claim 1, wherein: the fluoride salt includes one or more of ammonium fluoride, ammonium bifluoride, and a metal fluoride salt.

3. An MXene two-dimensional material according to claim 1, wherein: the molar ratio of the fluorine salt to the boric acid in the mixed solution is 0.01-0.3: 0.02-1.5.

4. An MXene two-dimensional material according to claim 1, wherein: the MXene precursor comprises Ti₃AlC₂、Ti₂AlC、V₂AlC、Mo₂AlC and Nb₂Any one or a combination of two or more of alcs.

5. A preparation method of MXene two-dimensional material is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: preparing reaction sediment liquid containing villiaumite and boric acid;

step two: placing the MXene precursor into the reaction deposition solution obtained in the first step to carry out hydrothermal reaction to obtain a suspension;

step three: and (4) performing centrifugal separation on the suspension liquid in the step two, taking the suspended substance, washing the suspended substance to be neutral, and drying to obtain the MXene two-dimensional material.

6. The method for preparing MXene two-dimensional material according to claim 5, wherein: and in the second step, ultrasonic treatment is carried out while the hydrothermal reaction is carried out.

7. The method for preparing MXene two-dimensional material according to claim 5, wherein: in the second step, the reaction temperature of the hydrothermal reaction is 90-180 ℃, and the reaction time is 1-12 h.

8. The method for preparing MXene two-dimensional material according to claim 5, wherein: in the second step, the hydrothermal reaction adopts a polyvinyl fluoride hydrothermal reaction kettle.

9. The method for preparing MXene two-dimensional material according to claim 5, wherein: in the third step, the drying process comprises the following specific steps: vacuum drying is adopted, and the drying temperature is 60-90 ℃.

10. An application of MXene two-dimensional material in preparing electrode.

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