A method for long-term stabilization of MXene aqueous dispersions using a three-dimensional particle electrode strategy

Abstract

The present invention discloses a method for long-term stabilization of MXene aqueous dispersion using a three-dimensional particle electrode strategy. The method comprises mixing π-conjugated monomers into the MXene aqueous dispersion and constructing a three-dimensional particle electrode system with suitable anode and cathode materials; treating the MXene nanosheets dispersed in water as particle electrodes and the π-conjugated monomers as pollutants; electrocatalytically oxidizing the π-conjugated monomers under suitable treatment process parameters; and in-situ depositing corresponding electroactive polymers on the surface and edge of the particle electrode (MXene sheet) to fully seal oxidation-sensitive sites and achieve long-term stabilization of the MXene aqueous dispersion. Even if interlayer water and oxygen are present during the process of preparing the film by vacuum filtration, the coated electroactive polymer can effectively protect the accumulated MXene nanosheets. While stabilizing MXene, the coated electroactive polymer also retains the charged properties of the nanosheets to the greatest extent possible, with little impact on subsequent practical applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of MXene materials, and in particular relates to a method for long-term stabilization of MXene aqueous dispersions using a three-dimensional particle electrode strategy. Background Art

[0002] Two-dimensional transition metal carbon (nitride) (MXene) has shown practical value in energy storage, electromagnetic shielding, sensing and catalysis due to its conductivity comparable to that of metals, high aspect ratio and hydrophilicity. However, MXene has poor chemical stability, especially in common aqueous solution storage environment, and it can be stored in a few days (for example, Ti3C2T x -MXene, for example, can completely oxidize, leading to structural collapse. This oxidation issue has become a bottleneck restricting the practical application of MXene materials.

[0003] Regarding post-treatment methods to improve the chemical stability of MXene colloidal solutions, there are currently existing methods to improve the chemical stability of MXene solutions or vacuum filtration membranes, such as adjusting the storage environment (such as inert atmosphere, low-temperature freezing, vacuum), thermal annealing, adding antioxidants to the solution, and surface modification. More representatively, the Green team (Langmuir, 2023, 39: 918-928) comprehensively compared the advantages and disadvantages of the above-mentioned post-treatment methods in blocking the oxidation process of MXene solutions. Zhang Han, Zhang Ye and collaborators (Advanced Materials, 2022, 34: 2107554) started from the preparation of MXene materials, explained the differences between the above-mentioned antioxidant methods and pointed out their applicability. Zhang Yizhou, Kang Qi and collaborators (Nano Research, 2022, 15: 6551-6567) also summarized the advantages and disadvantages of the above-mentioned antioxidant methods.

[0004] In the above domestic and foreign review, surface modification (coating with a protective layer) of MXene dispersed nanosheets or vacuum filtration membranes in solution can passivate oxidation-sensitive sites such as edges or defects, thereby exerting a long-lasting antioxidant effect. In the closest prior art, Choi et al. (Carbon, 2022, 191: 593-599) used an immersion coating method to deposit MXene on Ti3C2T xA ZIF-8 layer is grown on the outer surface of the MXene filtration membrane to provide protection. Similarly, high-temperature annealing to form a TiO2 layer (ACS Applied Nano Materials, 2020, 3:10578-10585) and a nanocarbon coating (Applied Surface Science, 2020, 502:144-171; Energy Storage Materials, 2020, 29:163-171; Advanced Materials, 2017, 29:1607-17) can both partially retard the oxidation process of the MXene filtration membrane. Compared to inorganic coatings, chemical grafting to form an organic coating on the surface of MXene filtration membranes or dispersed nanosheets is more operationally simple. Aminosilane (FlatChem, 2019, 17:100128; Journal of Materials Science & Technology, 2020, 54:144-159), filamentous protein (Advanced Functional Materials, 2020, 30:2004554), tetradecyl phosphate (Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021, 625:126903), perfluorodecyl methacrylate (ACS Nano, 2023, 17:10898-10905), and catecholamines (Small, 2023, 19:2304278) can all be coated on the surface of MXene filtration membranes or nanosheets to provide protection. Synthetic polymer coatings are denser than single small molecules and have stronger adhesion to the MXene matrix, thus providing a better antioxidant effect. Polyethyleneimine (Nature Communications, 2023, 14: 7392; Materials Letters, 2023, 337: 133979) and polydopamine (ACS Nano, 2020, 14: 11722-11732; Langmuir, 2023, 39: 9453-9467) have been used to improve the chemical stability of MXene films or dispersed nanosheets.

[0005] Analysis of the above-mentioned closest prior art reveals the following problems:

[0006] ① The techniques used to coat ZIF-8, carbon, and TiO2 layers, such as solution impregnation, high-temperature annealing, or chemical vapor deposition, can cause MXene oxidation.

[0007] ② The MXene-coated filtration membrane does not fundamentally eliminate the interlayer water and oxygen (oxidation inducers) of MXene, making it prone to oxidation from the inside out;

[0008] ③ To coat MXene nanosheets dispersed in water, in addition to adding the coating body (such as polymer monomer), an additional initiator with oxidizing properties is required, which is not conducive to the stability of the modified MXene colloidal solution and affects its purity and physicochemical properties;

[0009] ④ The coating layers described in the prior art all have adverse effects on the electrical and electrochemical properties of MXene films or nanosheets. Summary of the Invention

[0010] In response to the above problems, the present invention starts from the source, takes the MXene nanosheets in the dispersion as the protection object, mixes in π-conjugated monomers, and constructs a three-dimensional particle electrode system with suitable anode and cathode materials; regards the MXene nanosheets dispersed in water as particle electrodes and the π-conjugated monomers as pollutants, and electrocatalytically oxidizes the π-conjugated monomers under suitable treatment process parameters. The corresponding electroactive polymer is deposited in situ on the surface and edge of the particle electrode (MXene sheet), fully sealing the oxidation-sensitive sites and achieving long-term stability of the MXene aqueous dispersion. Even if there is interlayer water and oxygen in the process of preparing the film by vacuum filtration, the coated electroactive polymer can effectively protect the accumulated MXene nanosheets. On the other hand, while stabilizing MXene, the coated electroactive polymer also retains the charged properties of the nanosheets to the maximum extent, with almost no impact on subsequent practical applications.

[0011] The method for long-term stabilization of MXene aqueous dispersion by the three-dimensional particle electrode strategy is:

[0012] ① Mix the π-conjugated monomer into the MXene aqueous dispersion and add a buffer solution to adjust the pH of the dispersion to 6-8. The final concentration of MXene in the dispersion is 0.02-2 mg / mL, and the concentration of the π-conjugated monomer is 0.05-0.2 mol / L.

[0013] ② Polish the surface of the anode plate and cathode plate, ultrasonically clean them in anhydrous ethanol, blow dry them with nitrogen, and then insert them into the electrolytic cell. The distance between the anode plate and cathode plate is 1-6 cm;

[0014] Pour the dispersion obtained in step ① into the electrolytic tank, control the temperature of the dispersion to 20-40°C, the voltage to 3-12V, and apply power for 5-50 minutes to obtain a long-lasting and stable MXene aqueous dispersion.

[0015] The π-conjugated monomer is one or more of 5-aminoindole, diphenylacetylene, naphthalene diimide, aniline, pyrrole, 3,4-ethylenedioxythiophene, and iminodiphenylene.

[0016] The MXene is Ti3C2T x , Ti2CT x , V2CT x , Nb2CT x , Mo2CT x , Ti3N2T x , Ti3CNT x One or more of the following, T is -O, -F, -OH, and x is 1 or 2.

[0017] The buffer solution is one or both of an ammonia-ammonium chloride buffer solution and a phosphate buffer solution.

[0018] The material selected for the anode plate is titanium-plated lead dioxide, TiO2-coated titanium electrode, platinum sheet, 304 stainless steel or graphite sheet.

[0019] The material selected for the cathode plate is titanium sheet, graphite sheet or 304 stainless steel.

[0020] The beneficial effects of the present invention include:

[0021] 1. The process is simple and easy to operate, which reduces the energy consumption required by traditional methods, facilitates pipeline operation, and produces stable MXene dispersions in batches.

[0022] 2. Realize in-situ conductive polymer coating of MXene nanosheets, which not only stabilizes the dispersion for a long time, but also improves the chemical stability of the corresponding filtration membrane under normal conditions.

[0023] 3. After in-situ coating, the charging properties and electrochemical properties of the MXene nanosheets and the corresponding filtration membrane in the water are not affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the three-dimensional particle electrode strategy of the present invention for long-term stable MXene aqueous dispersion.

[0025] Figure 2 The long-lasting and stable Ti3C2T obtained in Example 1 x UV-visible spectrum of the aqueous dispersion as a function of time.

[0026] Figure 3 The long-lasting and stable Ti2CT obtained in Example 2 x UV-visible spectrum of the aqueous dispersion as a function of time.

[0027] Figure 4 The long-lasting and stable V2CT obtained in Example 3 x The appearance of the aqueous dispersion after storage at room temperature for 20 days is compared with that of the untreated V2CT.x The solution changes of the aqueous dispersion are compared.

[0028] Figure 5 The long-lasting and stable Ti3N2T obtained in Example 6 x Transmission electron microscopy images of nanosheets after 30 days of storage at room temperature, compared with images of untreated samples. DETAILED DESCRIPTION

[0029] Example 1:

[0030] (1) 5.0 g Ti3AlC2 and 3.5 g LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80 °C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40 °C and 35 kHz to obtain Ti3C2T x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Ti3C2T x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 0.5 mg / mL with deionized water. 5-aminoindole monomer was mixed with 0.5 mg / mL Ti3C2T x Ammonia (final concentration: 0.01 mol / L)-ammonium chloride (final concentration: 0.177 mol / L) buffer solution was added to the aqueous dispersion to adjust the pH to 7, and the final 5-aminoindole concentration was 0.1 mol / L;

[0031] (2) Platinum sheet was selected as anode and titanium sheet as cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen and then inserted into the electrolytic cell. The distance between the anode and cathode was 3 cm, and the effective area of ​​the plate was 15 cm. 2 ;

[0032] (3) Pour 500 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 25 ° C, the voltage to 6 V, and after energizing for 20 minutes, remove the electrode plate to obtain a long-lasting and stable Ti3C2T x Aqueous dispersion.

[0033] The experimental results show that the Ti3C2T x After the dispersion was sealed and stored at 25℃ for 30 days, the UV-visible spectrum curve remained stable (see Appendix Figure 2 ), and the solution color did not change significantly, showing an excellent stabilizing effect.

[0034] Example 2:

[0035] (1) 5.0 g Ti2AlC and 3.5 g LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80 °C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40 °C and 35 kHz to obtain Ti2CT x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Ti2CT x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 2 mg / mL using deionized water; diphenylacetylene monomer was mixed with 2 mg / mL Ti2CT x Phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.05 mol / L; final concentration of potassium hydrogen phosphate: 0.031 mol / L) was added to the aqueous dispersion to adjust the pH to 6.5, and the final concentration of diphenylacetylene was 0.15 mol / L;

[0036] (2) A TiO2-coated titanium electrode was selected as the anode and a graphite sheet as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 4 cm, and the effective area of ​​the plate was 12 cm. 2 ;

[0037] (3) Pour 300 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 30 ° C, the voltage to 8 V, and after energizing for 30 minutes, remove the electrode plate to obtain a long-term stable Ti2CT x Aqueous dispersion.

[0038] The experimental results show that the Ti2CT x After the dispersion was sealed and stored at 25℃ for 7 days, the UV-visible spectrum curve remained stable (see Appendix Figure 3 ), and the solution color did not change significantly, showing an excellent stabilizing effect.

[0039] Example 3:

[0040] (1) 5.0 g of V2AlC and 3.5 g of LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL of HCl solution (5 mol / L) was poured into the bottle and stirred at 80°C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40°C and 35 kHz to obtain V2CT.x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing the specific volume V2CT x The dry mass of the dispersion was used to obtain its concentration, which was diluted to 0.5 mg / mL using deionized water; naphthalene diimide was mixed with 0.5 mg / mL of V2CT x To the aqueous dispersion, an ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.02 mol / L; final concentration of ammonium chloride: 0.036 mol / L) and a phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.1 mol / L; final concentration of potassium hydrogen phosphate: 0.062 mol / L) were added to adjust the pH to 7.5. The final concentration of naphthalenediimide was 0.2 mol / L.

[0041] (2) Platinum sheet was selected as anode and 304 stainless steel as cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen and inserted into the electrolytic cell. The distance between the anode and cathode was 5 cm and the effective area of ​​the plate was 10 cm. 2 ;

[0042] (3) Pour 300 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 35°C and the voltage to 10V, and after energizing for 40 minutes, remove the electrode plate to obtain a long-term stable V2CT x Aqueous dispersion.

[0043] Experimental results show that the V2CT obtained by this method x After the dispersion was sealed and stored at 25°C for 20 days, the UV-visible spectrum curve remained stable and the color of the solution did not change significantly ( Figure 4 ), showing excellent stabilizing effect.

[0044] Example 4:

[0045] (1) 5.0 g Nb2AlC and 3.5 g LiF powder were mixed and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80°C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40°C and 35 kHz to obtain Nb2CT x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Nb2CT x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 0.1 mg / mL using deionized water; aniline was mixed with 0.1 mg / mL of Nb2CT xPhosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.01 mol / L; final concentration of potassium hydrogen phosphate: 0.006 mol / L) was added to the aqueous dispersion to adjust the pH to 6.8, and the final aniline concentration was 0.05 mol / L;

[0046] (2) 304 stainless steel was selected as the anode and graphite sheet as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 2 cm, and the effective area of ​​the plate was 20 cm. 2 ;

[0047] (3) Pour 250 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 40 ° C, the voltage to 12 V, and after energizing for 5 minutes, remove the electrode plate to obtain a long-term stable Nb2CT x Aqueous dispersion.

[0048] The experimental results show that the Nb2CT x After the dispersion was sealed and stored at 25°C for 25 days, the UV-visible spectral curve remained stable and the color of the solution did not change significantly, demonstrating an excellent stabilization effect.

[0049] Example 5:

[0050] (1) 5.0 g of Mo2AlC and 3.5 g of LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL of HCl solution (5 mol / L) was poured into the bottle and stirred at 80°C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40°C and 35 kHz to obtain Mo2CT x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Mo2CT x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 1 mg / mL using deionized water; pyrrole was mixed with 1 mg / mL of Mo2CT x To the aqueous dispersion, an ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.001 mol / L; final concentration of ammonium chloride: 0.562 mol / L) and a phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.01 mol / L; final concentration of potassium hydrogen phosphate: 0.006 mol / L) were added to adjust the pH to 6.2, and the final pyrrole concentration was 0.1 mol / L;

[0051] (2) Titanium-plated lead dioxide was selected as the anode and 304 stainless steel was used as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 6 cm, and the effective area of ​​the plate was 18 cm. 2 ;

[0052] (3) Pour 350 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 32 ° C, the voltage to 9 V, and after energizing for 22 minutes, remove the electrode plate to obtain a long-lasting and stable Mo2CT x Aqueous dispersion.

[0053] The experimental results show that the Mo2CT x After the dispersion was sealed and stored at 25°C for 25 days, the UV-visible spectral curve remained stable and the color of the solution did not change significantly, demonstrating an excellent stabilization effect.

[0054] Example 6:

[0055] (1) 5.0 g Ti3AlN2 and 3.5 g LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80 °C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40 °C and 35 kHz to obtain Ti3N2T x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Ti3N2T x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 0.6 mg / mL with deionized water. 3,4-EDT was mixed with 0.6 mg / mL Ti3N2T x Ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.005 mol / L; final concentration of ammonium chloride: 0.88 mol / L) and phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.5 mol / L; final concentration of potassium hydrogen phosphate: 0.003 mol / L) were added to the aqueous dispersion to adjust the pH to 6.2. The final concentration of 3,4-ethylenedioxythiophene was 0.1 mol / L.

[0056] (2) 304 stainless steel was selected as the anode and titanium sheet as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 4 cm, and the effective area of ​​the plate was 20 cm. 2 ;

[0057] (3) Pour 400 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 30 ° C, the voltage to 10 V, and after energizing for 30 minutes, remove the electrode plate to obtain a long-lasting and stable Ti3N2T x Aqueous dispersion.

[0058] The experimental results show that the Ti3N2T x After the dispersion was sealed and stored at 25°C for 30 days, the UV-visible spectrum curve remained stable and the color of the solution did not change significantly. At the same time, the transmission electron microscopy photos showed that Ti3N2T x The nanosheet structure is complete ( Figure 5 ), showing excellent stabilizing effect.

[0059] Example 7:

[0060] (1) 5.0 g Ti3AlN2 and 3.5 g LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80 ° C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40 ° C and 35 kHz to obtain Ti3NT x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Ti3NT x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 1.5 mg / mL with deionized water. Iminodiphenylene was mixed with 1.5 mg / mL Ti3N2T x To the aqueous dispersion, an ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.005 mol / L; final concentration of ammonium chloride: 0.8 mol / L) and a phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.1 mol / L; final concentration of potassium hydrogen phosphate: 0.014 mol / L) were added to adjust the pH to 7.1. The final concentration of iminodiphenylene was 0.05 mol / L.

[0061] (2) A TiO2-coated titanium electrode was selected as the anode and 304 stainless steel as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 6 cm, and the effective area of ​​the plate was 10 cm. 2 ;

[0062] (3) Pour 450 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 25 ° C, the voltage to 3 V, and after 50 minutes of power on, remove the electrode plate to obtain a long-lasting and stable Ti3N2T x Aqueous dispersion.

[0063] The experimental results show that the Ti3N2T x After the dispersion was sealed and stored at 25°C for 30 days, the UV-visible spectral curve remained stable and the color of the solution did not change significantly, showing an excellent stabilization effect.

[0064] Example 8:

[0065] (1) 5.0 g Ti3AlCN and 3.5 g LiF powder were mixed evenly and added to a polypropylene bottle; 100 mL HCl solution (5 mol / L) was poured into the bottle and stirred at 80 °C and 600 r / min for 12 h; after stirring, the mixed solution was centrifuged at 2600 r / min for 1 h, the lower precipitate was removed, and repeatedly rinsed with deionized water until the pH of the rinse water reached 6.0; the washed precipitate was ultrasonically dispersed at 40 °C and 35 kHz to obtain Ti3CNT x Aqueous dispersion (T is -O, -F, -OH, x is 2). By weighing a specific volume of Ti3CNT x The dry mass of the dispersion was measured to obtain its concentration, which was diluted to 0.02 mg / mL with deionized water; naphthalene diimide was mixed with 0.02 mg / mL of Ti3CNT x To the aqueous dispersion, an ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.01 mol / L; final concentration of ammonium chloride: 0.018 mol / L) was added to adjust the pH to 8, and the final concentration of naphthalene diimide was 0.1 mol / L;

[0066] (2) Titanium-coated lead dioxide was selected as the anode and graphite sheet as the cathode. The surface was polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 5 cm, and the effective area of ​​the plate was 16 cm. 2 ;

[0067] (3) Pour 500 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 20 ° C, the voltage to 5 V, and after energizing for 40 minutes, remove the electrode plate to obtain long-term stable Ti3CNT x Aqueous dispersion.

[0068] The experimental results show that the Ti3CNT x After the dispersion was sealed and stored at 25°C for 15 days, the UV-visible spectral curve remained stable and the color of the solution did not change significantly, demonstrating an excellent stabilization effect.

[0069] Example 9:

[0070] (1) Prepare Ti3C2T by referring to step (1) of Example 1 xThe aqueous dispersion (T is -O, -F, -OH, x is 2) was diluted to a concentration of 0.05 mg / mL with deionized water; 3,4-ethylenedioxythiophene and aniline were mixed into 0.05 mg / mL Ti3C2T x Phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.1 mol / L; final concentration of potassium hydrogen phosphate: 0.062 mol / L) was added to the aqueous dispersion to adjust the pH to 6.5. The final concentrations of 3,4-ethylenedioxythiophene and aniline were both 0.05 mol / L.

[0071] (2) Graphite sheets were selected as anodes and titanium sheets as cathodes. The surfaces were polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 3 cm, and the effective area of ​​the plates was 12 cm. 2 ;

[0072] (3) Pour 380 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 30 ° C, the voltage to 10 V, and after energizing for 8 minutes, remove the electrode plate to obtain a long-lasting and stable Ti3C2T x Aqueous dispersion.

[0073] The experimental results show that the Ti3C2T x After the dispersion was sealed and stored at 25°C for 30 days, the UV-visible spectral curve remained stable and the color of the solution did not change significantly, showing an excellent stabilization effect.

[0074] Example 10:

[0075] (1) Prepare Ti3C2T by referring to step (1) of Example 1 x Aqueous dispersion (T is -O, -F, -OH, x is 2); Ti2CT was prepared by referring to step (1) of Example 2 x Aqueous dispersion (T is -O, -F, -OH, x is 2); take appropriate amounts of the above two MXene dispersions, mix and dilute them to make the total concentration of MXene in water 1 mg / mL (Ti3C2T x With Ti2CT x Each accounts for 50%); Pyrrole is mixed into Ti3C2T x With Ti2CT x To the mixed aqueous dispersion, an ammonia-ammonium chloride buffer solution (final concentration of ammonia: 0.001 mol / L; final concentration of ammonium chloride: 0.18 mol / L) and a phosphate buffer solution (final concentration of potassium dihydrogen phosphate: 0.002 mol / L; final concentration of potassium hydrogen phosphate: 0.9 mol / L) were added to adjust the pH to 7, and the final pyrrole concentration was 0.2 mol / L;

[0076] (2) Platinum sheets were selected as anodes and graphite sheets as cathodes. The surfaces were polished, ultrasonically cleaned in anhydrous ethanol, dried with nitrogen, and then inserted into the electrolytic cell. The distance between the anode and cathode was 5 cm, and the effective area of ​​the plates was 18 cm. 2 ;

[0077] (3) Pour 500 mL of the dispersion obtained in step (1) into the electrolytic cell, control the temperature of the dispersion to 35 ° C, the voltage to 10 V, and after 10 minutes of power on, remove the electrode plate to obtain a long-term stable Ti3C2T x With Ti2CT x Aqueous dispersion.

[0078] The experimental results show that the Ti3C2T x With Ti2CT x After the mixture was sealed and stored at 25°C for 30 days, the UV-visible spectrum curve remained stable and the color of the solution did not change significantly, showing an excellent stabilization effect.

Claims

1. A method for long-term stabilization of MXene aqueous dispersion using a three-dimensional particle electrode strategy, characterized in that: The specific steps of the method are: ① Mix the π-conjugated monomer into the MXene aqueous dispersion and add a buffer solution to adjust the pH of the dispersion to 6-8. The final concentration of MXene in the dispersion is 0.02-2 mg / mL, and the concentration of the π-conjugated monomer is 0.05-0.2 mol / L. ② Polish the surface of the anode plate and cathode plate, ultrasonically clean them in anhydrous ethanol, blow dry them with nitrogen, and then insert them into the electrolytic cell. The distance between the anode plate and cathode plate is 1-6 cm; Pour the dispersion obtained in step ① into the electrolytic tank, control the temperature of the dispersion to 20-40°C, the voltage to 3-12V, and apply power for 5-50 minutes to obtain a long-lasting and stable MXene aqueous dispersion.

2. The method according to claim 1, characterized in that The π-conjugated monomer is one or more of 5-aminoindole, diphenylacetylene, naphthalene diimide, aniline, pyrrole, 3,4-ethylenedioxythiophene, and iminodiphenylene.

3. The method according to claim 1, characterized in that The MXene is Ti3C2T x , Ti2CT x , V2CT x , Nb2CT x , Mo2CT x , Ti3N2T x , Ti3CNT x One or more of the following, T is -O, -F, -OH, and x is 1 or 2.

4. The method according to claim 1, wherein The buffer solution is one or both of an ammonia-ammonium chloride buffer solution and a phosphate buffer solution.

5. The method according to claim 1, wherein The material selected for the anode plate is titanium-plated lead dioxide, TiO2-coated titanium electrode, platinum sheet, 304 stainless steel or graphite sheet.

6. The method according to claim 1, characterized in that The material selected for the cathode plate is titanium sheet, graphite sheet or 304 stainless steel.

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