1. The preparation method of the oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material is characterized by comprising the following steps:

the method comprises the following steps: mixing M-position metal powder, Al powder, C powder and M-position metal oxide MO_xThe powder is fully mixed according to the molar ratio of (3-y) to (2-xy) to y or (2-y) to (1.2 to (1-xy) to y, wherein the range of x is 0-3, the range of y is 0-0.2, and the mixture is sintered at the temperature of 1300-1500 ℃ in an inert atmosphere to obtain the MAX phase material doped with oxygen atoms;

step two: adding villiaumite into acid to form a fluorine-containing acidic etching agent, reacting the fluorine-containing acidic etching agent with the MAX phase material doped with oxygen atoms obtained in the first step at the temperature of 20-50 ℃ to etch off an A atomic layer in the MAX phase material doped with oxygen atoms in situ, stripping with the aid of ultrasound after the reaction is finished, and centrifuging and washing for multiple times until the pH value is 6-7 to obtain MXene nanosheets doped with oxygen atoms in situ; wherein the mass ratio of the oxygen atom-doped MAX phase material to the fluorine salt is 1: (0.1-2), the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: (5-50);

step three: and D, dispersing the oxygen atom in-situ doped MXene nanosheets obtained in the step two in deionized water to prepare a suspension, and performing vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

2. The method for preparing an oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material as claimed in claim 1, wherein in the first step, M site metal is any one or two of Sc, Ti, Cr, Y, V, Mo, Zr, Nb, Hf, Ta and W, and the two metals are mixed in any ratio.

3. The method for preparing an oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material as claimed in claim 1, wherein in the step one, M-site metal powder, Al powder, C powder and M-site metal oxide powder are mechanically mixed for 5-20 min by ethanol assistance, and after being fully mixed, the ethanol is removed by drying.

4. The method for preparing an oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material according to claim 1, wherein in the step one, the sintering time is 0.5-9 h, the inert atmosphere is argon, and the product is ground after sintering to obtain MAX phase ceramic powder doped with oxygen atoms of less than 400 meshes.

5. The method for preparing an oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material according to claim 1, wherein the content of oxygen atoms replacing carbon atoms in the oxygen atom doped MAX phase material obtained in the first step is 0-20%.

6. The method for preparing an oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material as claimed in claim 1, wherein in the second step, the villiaumite comprises lithium fluoride, sodium fluoride, potassium fluoride or ammonium fluoride, the acid comprises hydrochloric acid or sulfuric acid, the villiaumite is slowly added into the acid to form a fluorine-containing acidic etchant, then the oxygen atom doped MAX phase material is slowly added into the fluorine-containing acidic etchant to react for 8-48 h, and magnetic stirring is performed during the reaction process.

7. The method for preparing the oxygen atom in-situ doped MAXe phase and MXene in-situ doped flexible membrane electrode material according to claim 1, wherein the content of oxygen atom substituted carbon atom in the oxygen atom in-situ doped MXene nanosheet obtained in the second step is 0-20%.

8. The method for preparing the oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material according to claim 1, wherein the oxygen atom in-situ doped MXene nanosheets in the third step are dispersed in deionized water for vacuum deoxygenation, and after the vacuum deoxygenation, ultrasonic treatment and centrifugal treatment are performed to obtain supernatant as suspension.

9. The oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material is characterized by being prepared by the preparation method of the oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material as claimed in any one of claims 1 to 8, the flexible membrane electrode material is an electrode material which is composed of MXene nanosheets and has a section with a laminated structure, and the volumetric specific capacity of the electrode reaches 1200-1500C g^-1。

10. The use of the oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material as a negative electrode material of a proton water system supercapacitor according to claim 9, wherein the proton water system supercapacitor uses Prussian blue analogue as a positive electrode material, and the energy density of the proton water system supercapacitor is 50-100 Wh L^-1The power density is 1-10 kW kg^-1。

Background

Electrochemical energy storage devices are by far one of the most important types of devices that dominate the field of energy storage and conversion, including conventional capacitors, supercapacitors and batteries (including Li)⁺、 Na⁺And K⁺A plasma metal ion battery). The super capacitor has high energy density compared with the traditional capacitor and higher power density compared with the ion battery, is an energy storage device between the traditional capacitor and the battery, and combines the advantages of the traditional capacitor and the battery. Thus, over the years, researchers have conducted intensive and extensive research into ultracapacitor energy storage systems. In addition, due to the environmental protection property, the high specific capacitance value, the rapid charge and discharge and the extremely potential storage capacity, the super capacitor has important application in the industrial fields of military affairs and automobiles, and the like, such as the aspects of heavy vehicles, hybrid power platforms of trucks/buses, regenerative braking energy storage of electric vehicles and light rails, and the like. However, the relatively low energy density of supercapacitors has tended to limit their widespread use. Especially considering the limitation of application scene space, developing a super capacitor with high volume energy density is a key problem to be solved urgently, and how to store energy efficiently and reduce the harm to the environment to the maximum extent is also a key challenge to be solved urgently.

Transition metal carbides, carbonitrides and nitrides (MXenes) are a new type of two-dimensional material. In 2011, the Gogotsi research team of the university of Derasel reports that MXene phase materials are successfully prepared by a hydrofluoric acid selective etching method for the first time. The formula of MXene material is M_n+1X_nT_xWherein M is an early transition metal (e.g. Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo or W), X is carbon and/or nitrogen n ═ 1-3, T_xIs a surfaceAtoms whose ends are bound to external M metal atoms, T_xX in (2) represents the number of surface functional groups. The surface functional groups are mainly O, -F and-OH, and some reports also show that Ti₃C₂T_xThe MXene surface termination functional group contains-Cl. The thickness of the two-dimensional MXene nano monolayer flake is in the range of 1nm, and the thickness can be changed from M by changing n in MXenes₂XT_xTo M₃X₂T_xAnd M₄X₃T_xTo control. However, MXene electrode materials still suffer from low yield, low activity of metal active center atoms (M site), and low energy storage density.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material, and a preparation method and application thereof.

In order to achieve the above object, the present invention provides a method for preparing an oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material, comprising:

the method comprises the following steps: mixing M-position metal powder, Al powder, C powder and M-position metal oxide MO_xThe powder is fully mixed according to the molar ratio of (3-y) to (2-xy) to y or (2-y) to (1.2 to (1-xy) to y, wherein the range of x is 0-3, the range of y is 0-0.2, and the mixture is sintered at the temperature of 1300-1500 ℃ in an inert atmosphere to obtain the MAX phase material doped with oxygen atoms;

step two: adding villiaumite into acid to form a fluorine-containing acidic etching agent, reacting the fluorine-containing acidic etching agent with the MAX phase material doped with oxygen atoms obtained in the first step at the temperature of 20-50 ℃ to etch off an A atomic layer in the MAX phase material doped with oxygen atoms in situ, stripping with the assistance of ultrasound after the reaction is finished, and performing centrifugal washing for multiple times until the pH value is 6-7 to obtain MXene nanosheets doped with oxygen atoms in situ; wherein the mass ratio of the oxygen atom-doped MAX phase material to the fluorine salt is 1: (0.1-2), the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: (5-50);

step three: and D, dispersing the oxygen atom in-situ doped MXene nanosheets obtained in the step two in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Preferably, in the first step, the M-site metal is any one or two of Sc, Ti, Cr, Y, V, Mo, Zr, Nb, Hf, Ta and W, and the two metals are mixed in any proportion.

Preferably, in the step one, the M-site metal powder, the Al powder, the C powder and the M-site metal oxide powder are mechanically mixed for 5 to 20min by the aid of ethanol, and are dried to remove the ethanol after being sufficiently mixed.

Preferably, in the first step, the sintering time is 0.5-9 h, the inert atmosphere is argon, and the product is ground after sintering to obtain MAX-phase ceramic powder doped with oxygen atoms of less than 400 meshes.

Preferably, the content of oxygen atoms replacing carbon atoms in the oxygen atom-doped MAX phase material obtained in the first step is 0-20%.

Preferably, in the second step, the fluorine salt comprises lithium fluoride, sodium fluoride, potassium fluoride or ammonium fluoride, the acid comprises hydrochloric acid or sulfuric acid, the fluorine salt is slowly added into the acid to form a fluorine-containing acidic etchant, then the oxygen atom-doped MAX phase material is slowly added into the fluorine-containing acidic etchant to react for 8-48 h, and magnetic stirring is performed during the reaction process.

Preferably, the content of oxygen atoms replacing carbon atoms in the oxygen atom in-situ doped MXene nanosheets obtained in the second step is 0-20%.

Preferably, in the third step, the oxygen atom in-situ doped MXene nanosheets are dispersed in deionized water for vacuum deoxygenation, and after the vacuum deoxygenation, ultrasonic treatment and centrifugal treatment are performed to obtain a supernatant, namely the suspension.

The invention also provides an oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material which is prepared by the preparation method of the oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material, wherein the flexible membrane electrode material is an electrode material which is composed of MXene nanosheets and has a section with a laminated structure, and the volumetric specific capacity of the electrode reaches 1200-1500C g^-1。

The invention also provides application of the oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material as a negative electrode material of a proton water system super capacitor, wherein the proton water system super capacitor takes a Prussian blue analogue as a positive electrode material, and the energy density of the proton water system super capacitor is 50-100 Wh L^-1The power density is 1-10 kW kg^-1。

Compared with the prior art, the preparation method takes the M-site powder, the Al powder, the C powder and the M-site metal oxide powder as raw materials, so that the precursor materials are fully and uniformly mixed, and then the powder materials are sintered at high temperature atmosphere to obtain the in-situ doped MAX phase material with accurately controllable oxygen atom doping amount. On the basis, a fluorine-containing acidic etching agent containing fluoride salt is used for etching atoms of a layer A in the MAX phase material, ultrasonic-assisted stripping and centrifugal washing are used for obtaining in-situ doped MXene nanosheets with accurately controlled oxygen atom doping amount, the MXene nanosheets are dispersed in deionized water to prepare suspension, the suspension is subjected to vacuum filtration and vacuum drying, and the flexible membrane electrode material is obtained^-1The conductivity can be adjusted from 12.3 Ω sq^-1Is increased to 5.9 omega sq^-1And above, the electrochemical energy storage density is as high as 50-100 Wh L^-1The flexible membrane electrode material has the characteristics of good conductivity, accurately controllable doping amount, high electrochemical activity of M-site metal atoms, high electrochemical energy storage density, high yield, large-scale development and application and the like, and can be applied to super electricityThe electrochemical performance of the fields of containers, lithium, sodium, potassium, zinc, aluminum, calcium and magnesium ion batteries and the like is excellent, the electrochemical performance has wide application prospect, particularly, the electrochemical material is used as a negative electrode material of a proton water system super capacitor, the proton water system super capacitor takes a Plumbum blue analogue as a positive electrode material, and the energy density of the proton water system super capacitor reaches 50-100 Wh L^-1The power density is 1-10 kW kg^-1And has excellent electrochemical performance.

Drawings

FIG. 1 is a scanning electron micrograph of an oxygen atom doped MAX phase material of example 1;

FIG. 2 is an X-ray diffraction pattern of the oxygen atom doped MAX phase materials of examples 1-4;

FIG. 3 is a graph of the X-ray photoelectron spectrum Ti 2p of the oxygen atom doped MAX phase material of example 1;

FIG. 4 is a transmission electron microscope image of the MXene flexible membrane electrode material doped with oxygen atoms in situ in example 1;

FIG. 5 is an electrode diagram of the flexible film in example 1;

FIG. 6 is an X-ray diffraction pattern of the MXene flexible membrane electrode material doped with oxygen atoms in situ in examples 1 to 4;

FIG. 7 is a high resolution plot of O1s XPS for the MXene flexible membrane electrode material doped with oxygen atoms in situ as in example 1;

FIG. 8 is an electrochemical performance diagram of the MXene flexible membrane electrode material doped with oxygen atoms of different contents in situ in examples 1 to 4.

Detailed Description

The present invention will be further explained with reference to the drawings and specific examples in the specification, and it should be understood that the examples described are only a part of the examples of the present application, and not all examples. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present application.

The invention provides a preparation method of an oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material, which comprises the following steps:

the method comprises the following steps: mixing M-position metal powder, Al powder, C powder and M-position metal oxide MO_xThe powder is fully mixed according to the molar ratio of (3-y) to (2-xy) to y or (2-y) to (1.2) to (1-xy) to y, wherein the value range of x is 0-3, the value range of y is 0-0.2, and the powder is sintered at the temperature of 1300-1500 ℃ in an inert atmosphere to obtain the MAX phase material doped with oxygen atoms; preferably, the M-site metal is any one or two of Sc, Ti, Cr, Y, V, Mo, Zr, Nb, Hf, Ta and W, and the two metals are mixed in any proportion; mechanically mixing the M-site metal powder, the Al powder, the C powder and the M-site metal oxide powder for 5-20 min by the aid of ethanol, and drying to remove the ethanol after fully mixing; the sintering time is 0.5-9 h, the inert atmosphere is argon, and the sintered product is ground to obtain MAX-phase ceramic powder doped with oxygen atoms of less than 400 meshes; the content of oxygen atoms replacing carbon atoms in the obtained oxygen atom-doped MAX phase material is 0-20%;

step two: adding villiaumite into acid to form a fluorine-containing acidic etching agent, reacting the fluorine-containing acidic etching agent with the MAX phase material doped with oxygen atoms obtained in the first step at the temperature of 20-50 ℃ to etch off an A atomic layer in the MAX phase material doped with oxygen atoms in situ, stripping with the assistance of ultrasound after the reaction is finished, and performing centrifugal washing for multiple times until the pH value is 6-7 to obtain MXene nanosheets doped with oxygen atoms in situ; wherein the mass ratio of the oxygen atom-doped MAX phase material to the fluorine salt is 1: (0.1-2), the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: (5-50); preferably, the fluorine salt comprises lithium fluoride, sodium fluoride, potassium fluoride or ammonium fluoride and the like, the acid comprises hydrochloric acid or sulfuric acid and the like, the fluorine salt is slowly added into the acid to form a fluorine-containing acidic etching agent, then the oxygen atom-doped MAX phase material is slowly added into the fluorine-containing acidic etching agent to react for 8-48 h, and magnetic stirring is carried out in the reaction process; the content of oxygen atoms replacing carbon atoms in the obtained oxygen atom in-situ doped MXene nanosheets is 0-20%;

step three: and D, dispersing the oxygen atom in-situ doped MXene nanosheets obtained in the step two in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material. Preferably, the MXene nanosheets doped with oxygen atoms in situ are dispersed in deionized water for vacuum deoxygenation, and after the vacuum deoxygenation, ultrasonic treatment and centrifugal treatment are carried out to obtain supernatant, namely suspension.

The invention also provides an oxygen atom in-situ doped MAX phase and in-situ doped MXene flexible membrane electrode material prepared by the preparation method, the flexible membrane electrode material is an electrode material which is composed of MXene nanosheets and has a section with a layered structure, and the specific volume capacity of the electrode is 1200-1500C g^-1Compared with the undoped MXene nanosheet, the yield is improved from 20% to 30% or above, the conductivity is greatly improved from 12.3 omega sq compared with the undoped MXene flexible film^-1Is increased to 5.9 omega sq^-1And the above. The invention also provides application of the oxygen atom in-situ doped MAX phase and MXene in-situ doped flexible membrane electrode material, which is applied to the fields of super capacitors, lithium, sodium, potassium, zinc, aluminum, calcium, magnesium ion batteries and the like, shows excellent electrochemical performance and has wide application prospect, and particularly is used as a negative electrode material of a proton water system super capacitor, the proton water system super capacitor takes a Prussian blue analogue as a positive electrode material, and the energy density of the proton water system super capacitor is 50-100 Wh L^-1The power density is 1-10 kW kg^-1And has excellent electrochemical performance.

The present invention will be described in detail with reference to specific examples.

Example 1:

the preparation method comprises the following steps:

firstly, taking metal Ti powder, Al powder, C powder and TiO powder with the molar ratio of 2.975:1.2:1.95:0.025₂100g of oxide powder is taken as a raw material, simple mechanical mixing is carried out by ethanol assistance, and residual ethanol is removed after drying for 10 hours at 40 ℃; sintering for 2h at 1350 ℃ in an argon atmosphere; further grinding the sintered product to obtain powder with the particle size less than 400 meshes, namely obtaining oxygen-doped MAX (Ti)₃AlC_1.95O_0.05) Phase ceramic powder; then 2g of lithium fluoride (LiF) was slowly added to 20mL of 9M aqueous hydrochloric acid (HCl) and stirred for 5 min; which in turn is mixed with 2g of Ti₃AlC_1.95O_0.05Slowly adding the mixture into the mixed solution to avoid side reactions caused by excessive heat release, magnetically stirring the mixture at the rotation speed of 200rpm for 24 hours at the temperature of 35 ℃, washing the mixture obtained by the reaction for multiple times by using deionized water after the reaction for 24 hours until the pH value of a supernatant is more than 6, shaking the mixture for 2 minutes in each washing process, and centrifuging the mixture for 2 minutes at the rotation speed of 3500 rpm; finally prepared Ti by centrifugation₃C₂T_xDispersing the substrate into 300mL of deionized water, then carrying out vacuum deoxygenation for one hour by using a vacuum pump, after the deoxygenation is finished, carrying out ultrasonic treatment on the mixed solution for 1 hour, and then centrifuging the mixed solution for 1 hour at 3500rpm to obtain a supernatant which is Ti₃C_1.95O_0.05T_xSuspending the solution in a certain amount of Ti₃AlC_2-δO_δT_xAnd (3) carrying out self-assembly suction filtration on the suspension to form a film by using a vacuum filtration method.

Example 2:

the preparation method comprises the following steps:

firstly, taking metal Ti powder, Al powder, C powder and TiO powder with the molar ratio of 2.985:1.2:1.97:0.015₂100g of oxide powder is taken as a raw material, simple mechanical mixing is carried out by ethanol assistance, and residual ethanol is removed after drying for 10 hours at 40 ℃; sintering for 2h at 1350 ℃ in an argon atmosphere; further grinding the sintered product to obtain powder with the particle size less than 400 meshes, namely obtaining oxygen-doped MAX (Ti)₃AlC_1.97O_0.03) Phase ceramic powder; then 2g of lithium fluoride (LiF) was slowly added to 10mL of 9M sulfuric acid (H)₂SO₄) Stirring in water solution for 5 min; secondly 2g of Ti₃AlC_1.97O_0.03Slowly adding the mixture into the mixed solution to avoid side reaction caused by excessive heat release, magnetically stirring the mixture at the rotation speed of 200rpm for 24 hours at the temperature of 35 ℃, washing the mixture obtained by the reaction for many times by using deionized water after the reaction for 24 hours until the pH value of a supernatant is more than 6, shaking the mixture for 2 minutes in each washing process, and centrifuging the mixture for 2 minutes at the rotation speed of 3500 rpm; finally prepared Ti by centrifugation₃C₂T_xDispersing the base material into 300mL of deionized water, then carrying out vacuum deoxygenation for one hour by using a vacuum pump, and mixing after the deoxygenation is finishedThe solution is firstly treated by ultrasonic for 1h and then centrifuged for 1h at 3500rpm, and the obtained supernatant is Ti₃C_1.97O_0.03T_xSuspending the solution in a certain amount of Ti₃C_1.97O_0.03T_xAnd (3) carrying out self-assembly suction filtration on the suspension to form a film by using a vacuum filtration method.

Example 3:

the preparation method comprises the following steps:

firstly, taking metal Ti powder, Al powder, C powder and TiO powder with the molar ratio of 2.96:1.2:1.92:0.04₂100g of oxide powder is taken as a raw material, simple mechanical mixing is carried out by the aid of ethanol, and the mixture is dried at 40 ℃ for 10 hours to remove residual ethanol; sintering for 2 hours at 1400 ℃ in an argon atmosphere; further grinding the sintered product to obtain powder with the particle size less than 400 meshes, namely obtaining oxygen-doped MAX (Ti)₃AlC_1.92O_0.08) Phase ceramic powder; then 2g of sodium fluoride (NaF) was slowly added to 20mL of 9M aqueous hydrochloric acid (HCl) and stirred for 5 min; secondly 2g of Ti₃AlC_1.92O_0.08Slowly adding the mixture into the mixed solution to avoid side reactions caused by excessive heat release, magnetically stirring the mixture at the rotation speed of 200rpm for 24 hours at the temperature of 35 ℃, washing the mixture obtained by the reaction for multiple times by deionized water after the reaction for 24 hours until the pH value of a supernatant is more than 6, shaking the mixture for 2 minutes in each washing process, and centrifuging the mixture for 2 minutes at the rotation speed of 3500 rpm; finally prepared Ti by centrifugation₃C₂T_xDispersing the bottom materials into 300mL of deionized water, then carrying out vacuum deoxygenation for one hour by using a vacuum pump, after the deoxygenation is finished, carrying out ultrasonic treatment on the mixed solution for 1 hour, and then centrifuging the mixed solution for 1 hour at 3500rpm to obtain a supernatant which is Ti₃C_1.92O_0.08T_xSuspending the solution in a certain amount of Ti₃C_1.92O_0.08T_xAnd (3) carrying out self-assembly suction filtration on the suspension to form a film by using a vacuum filtration method.

Example 4:

the preparation method comprises the following steps:

firstly, taking metal Ti powder, Al powder, C powder and TiO powder with the molar ratio of 2.9:1.2:1.90:0.05₂Oxide powder 100g as raw material is extracted with ethanolAuxiliary simple mechanical mixing, drying at 40 deg.C for 10h to remove residual ethanol; sintering for 2 hours at 1400 ℃ in an argon atmosphere; further grinding the sintered product to obtain powder with the particle size less than 400 meshes, namely obtaining oxygen-doped MAX (Ti)₃AlC_1.90O_0.10) Phase ceramic powder; then 2g of potassium fluoride (KF) was slowly added to 20mL of 9M aqueous hydrochloric acid (HCl) and stirred for 5 min; secondly 2g of Ti₃AlC_1.90O_0.10Slowly adding the mixture into the mixed solution to avoid side reactions caused by excessive heat release, magnetically stirring the mixture at the rotation speed of 200rpm for 24 hours at the temperature of 35 ℃, washing the mixture obtained by the reaction for many times by using deionized water after the reaction for 24 hours until the pH value of a supernatant is more than 6, shaking the mixture for 2 minutes in each washing process, and centrifuging the mixture for 2 minutes at the rotation speed of 3500 rpm; finally prepared Ti by centrifugation₃C₂T_xDispersing the bottom materials into 300mL of deionized water, then carrying out vacuum deoxygenation for one hour by using a vacuum pump, after the deoxygenation is finished, carrying out ultrasonic treatment on the mixed solution for 1 hour, and then centrifuging the mixed solution for 1 hour at 3500rpm to obtain a supernatant which is Ti₃C_1.90O_0.10T_xSuspending the solution in a certain amount of Ti₃C_1.90O_0.10T_xAnd (3) carrying out self-assembly suction filtration on the suspension to form a film by using a vacuum filtration method.

The oxygen atom-doped MAX phase material of example 1 was analyzed by scanning electron microscopy, and as a result, referring to fig. 1, it can be seen from fig. 1 that the prepared oxygen atom-doped MAX phase has a distinct layered structure and is consistent with the morphology of the undoped MAX phase.

The X-ray diffraction analysis of the oxygen atom doped MAX phase materials of examples 1-4 showed that the crystal structure of the prepared oxygen atom doped MAX phase undoped MAX phase forms are consistent as shown in FIG. 2.

X-ray photoelectron spectroscopy Ti 2p analysis was performed on the oxygen atom doped MAX phase material of example 1, and the results are shown in fig. 3, where it can be seen that the presence of Ti-O bonds demonstrates the successful substitution of carbon atoms between the MAX phase layers by oxygen atoms.

MXene in-situ doping of oxygen atoms in Flexible Membrane electrode Material of example 1The results of the analysis by the line transmission electron microscope are shown in fig. 4, and it can be seen from fig. 4 that the prepared MXene nanosheet doped with oxygen atoms has an ultrathin layered structure, and the prepared MXene nanosheet is prepared into the flexible membrane electrode shown in fig. 5, and the specific volume capacity of the electrode reaches 1200-1500C g^-1The conductivity is improved to 5.9 omega sq^-1And above, the electrochemical energy storage density is as high as 50-100 Wh L^-1。

The X-ray diffraction analysis of the oxygen atom in-situ doped MXene flexible membrane electrode materials in examples 1 to 4 is performed, and as shown in fig. 6, it can be seen from fig. 6 that the interlayer distance of the oxygen atom doped MXene flexible membrane electrode is further increased compared with that of undoped MXene, which is beneficial to the electrochemical reaction.

The O1s XPS high resolution analysis was performed on the MXene flexible membrane electrode material doped with oxygen atoms in situ in example 1, and the results are shown in fig. 7. it can be seen from fig. 7 that the crystal structure of MXene is not affected by the oxygen atom doping in situ, Ti₃C₂T_xMXene mainly consists of O-Ti-O, C-Ti-O, C-Ti-OH and surface adsorbed H₂And (C) O. Wherein it can be clearly observed that the content of C-Ti-O increases significantly with increasing oxygen doping amount, while the content of C-Ti-OH decreases with increasing oxygen doping amount.

The electrochemical performance analysis is performed on the MXene flexible membrane electrode materials with different oxygen atom contents in the embodiments 1 to 4, and the result is shown in FIG. 8, and it can be seen from FIG. 8 that the energy storage density of the MXene flexible membrane electrode materials after oxygen atom doping is greatly improved.

Example 5:

the preparation method comprises the following steps:

firstly, taking metal Ti powder, Al powder, C powder and TiO powder with the molar ratio of 2.9:1.2:1.90:0.10₂100g of oxide powder is taken as a raw material, simple mechanical mixing is carried out by the aid of ethanol, and residual ethanol is removed after drying for 10 hours at 40 ℃; sintering for 2h at 1500 ℃ in an argon atmosphere; further grinding the sintered product to obtain powder with the particle size less than 400 meshes, namely obtaining oxygen-doped MAX (Ti)₃AlC_1.80O_0.20) Phase ceramic powder; then 2g of ammonium fluoride (NH)₄F) Slowly added to 20mL of 9M aqueous hydrochloric acid (HCl)Neutralizing and stirring for 5 min; secondly 2g of Ti₃AlC_1.90O_0.20Slowly adding the mixture into the mixed solution to avoid side reactions caused by excessive heat release, magnetically stirring the mixture at the rotation speed of 200rpm for 24 hours at the temperature of 35 ℃, washing the mixture obtained by the reaction for multiple times by deionized water after the reaction for 24 hours until the pH value of a supernatant is more than 6, shaking the mixture for 2 minutes in each washing process, and centrifuging the mixture for 2 minutes at the rotation speed of 3500 rpm; finally prepared Ti by centrifugation₃C₂T_xDispersing the bottom materials into 300mL of deionized water, then carrying out vacuum deoxygenation for one hour by using a vacuum pump, after the deoxygenation is finished, carrying out ultrasonic treatment on the mixed solution for 1 hour, and then centrifuging the mixed solution for 1 hour at 3500rpm to obtain a supernatant which is Ti₃C_1.90O_0.10T_xSuspending the solution in a certain amount of Ti₃C_1.90O_0.10T_xAnd (3) carrying out self-assembly suction filtration on the suspension to form a film by using a vacuum filtration method.

Example 6:

the preparation method comprises the following steps:

firstly, taking Sc metal powder, Al powder, C powder and Sc₂O₃Powder, in a molar ratio of 2.8: 12: 1.7: 0.2, mechanically mixing for 5min by aid of ethanol, drying and removing the ethanol after fully mixing, sintering at 1300 ℃ in an inert atmosphere for 9h in argon, and grinding the product after sintering to obtain MAX-phase ceramic powder doped with oxygen atoms of less than 400 meshes; slowly adding potassium fluoride into hydrochloric acid to prepare a fluorine-containing acid etching agent, slowly adding an oxygen atom-doped MAX phase material into a fluorine-containing acid etching agent, reacting the fluorine-containing acid etching agent with the oxygen atom-doped MAX phase material at the temperature of 20 ℃, reacting for 48 hours, performing magnetic stirring in the reaction process to etch off an A atomic layer in the oxygen atom in-situ doped MAX phase material, stripping with the aid of ultrasound after the reaction is finished, and performing centrifugal washing for multiple times until the pH value is 6 to obtain an oxygen atom in-situ doped MXene nanosheet, wherein the mass ratio of the oxygen atom-doped MAX phase material to the potassium fluoride is 1: 0.1, the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: 5; finally, the oxygen atom is oxidizedAnd dispersing the position-doped MXene nanosheets in deionized water for vacuum deoxygenation, performing ultrasonic treatment and then performing centrifugal treatment after the vacuum deoxygenation to obtain supernatant, namely suspension, and performing vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 7:

the preparation method comprises the following steps:

firstly taking Cr powder, Al powder, C powder and Cr₂O₃Mechanically mixing the powder with ethanol at a molar ratio of 1.9:1.2:0.85:0.1 for 20min, and drying to remove ethanol; sintering at 1500 ℃ for 0.5h under inert atmosphere, and grinding the product after sintering to obtain MAX-phase ceramic powder doped with oxygen atoms of less than 400 meshes; adding ammonium fluoride into hydrochloric acid to prepare a fluorine-containing acid etching agent, reacting the fluorine-containing acid etching agent with the MAX phase material doped with oxygen atoms obtained in the first step at the temperature of 50 ℃ to etch off an A atomic layer in the MAX phase material doped with oxygen atoms in situ, after the reaction is finished, carrying out ultrasonic-assisted stripping, and carrying out centrifugal washing for many times until the pH value is 7 to obtain MXene nanosheets doped with oxygen atoms in situ; wherein the mass ratio of the oxygen atom-doped MAX phase material to the fluorine salt is 1: 2, the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: 50; and finally, dispersing the MXene nano-sheets doped with oxygen atoms in situ in deionized water for vacuum deoxygenation, performing ultrasonic treatment and centrifugal treatment after the vacuum deoxygenation to obtain supernatant, namely suspension, and performing vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 8:

the preparation method comprises the following steps: firstly taking Y powder, V powder, Al powder, C powder and Y powder₂O₃Powders and V₂O₅Powder, wherein the molar ratio of M-site metal powder, Al powder, C powder and M-site metal oxide powder is 2.8: 1.2: 1.4: 0.2, Y and V powders and Y₂O₃Powders and V₂O₅The powder is mixed in any proportion and sintered at 1400 ℃ to obtain the MAX phase material doped with oxygen atoms; MAX phase material doped with oxygen atoms and containingReacting the hydrofluoric acid etching agent at the temperature of 30 ℃, ultrasonically assisting stripping after reaction, and centrifugally washing for many times until the pH value is 6-7 to obtain the oxygen atom in-situ doped MXene nanosheet, wherein the mass ratio of the oxygen atom doped MAX phase material to the villaumite is 1: 1, the mass volume ratio of the oxygen atom doped MAX phase material to the fluorine-containing acidic etching agent is 1: 30, of a nitrogen-containing gas; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 9:

the preparation method comprises the following steps: firstly, taking the molar ratio of 1.9:1.2:0.7:0.1 of Mo powder, Al powder, C powder and MoO₃Uniformly mixing the powder, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom-doped MAX phase material with a fluorine-containing acidic etching agent, ultrasonically assisting to strip, centrifuging and washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 10:

the preparation method comprises the following steps: firstly, taking the molar ratio of 2.8: 1.2: 1.4: 0.2 of Zr powder, Al powder, C powder and ZrO₂Uniformly mixing the powder, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom-doped MAX phase material with a fluorine-containing acidic etching agent, ultrasonically assisting to strip, centrifuging and washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 11:

the preparation method comprises the following steps: firstly, uniformly mixing Nb powder, Al powder and C powder in a molar ratio of 2:1.2:1, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom doped MAX phase material with a fluorine-containing acidic etching agent, carrying out ultrasonic-assisted stripping, and carrying out centrifugal washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 12:

the preparation method comprises the following steps: firstly, taking the molar ratio of 1.85: 1.2:0.7: 0.15 of Hf powder, Al powder, C powder and HfO₂Uniformly mixing the powder, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom-doped MAX phase material with a fluorine-containing acidic etching agent, ultrasonically assisting to strip, centrifuging and washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 13:

the preparation method comprises the following steps: firstly, taking the molar ratio of 2.95: 1.2: 1.875: 0.05 of Ta powder, Al powder, C powder and Ta₂O₅Uniformly mixing the powder, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom-doped MAX phase material with a fluorine-containing acidic etching agent, ultrasonically assisting to strip, centrifuging and washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Example 14:

the preparation method comprises the following steps: firstly taking W powder, Al powder, C powder and WO powder with the molar ratio of 1.9:1.2:0.7:0.1₃Uniformly mixing the powder, and sintering to obtain an oxygen atom doped MAX phase material; then reacting the oxygen atom-doped MAX phase material with a fluorine-containing acidic etching agent, ultrasonically assisting to strip, and centrifugally washing to obtain an oxygen atom in-situ doped MXene nanosheet; and finally, dispersing the oxygen atom in-situ doped MXene nanosheets in deionized water to prepare a suspension, and carrying out vacuum filtration and vacuum drying on the suspension to obtain the flexible membrane electrode material.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.