Low-fluorine MXene material and preparation method and application thereof

Abstract

This invention discloses a low-fluorine MXene material, its preparation method, and its applications. The preparation method of the low-fluorine MXene material of this invention includes the following steps: mixing fluorine-containing MXene, caustic alkali, strontium salt, polyol, and water for reaction; then separating the products; washing the products with hydrochloric acid to obtain the low-fluorine MXene material. The preparation method of the low-fluorine MXene material of this invention has advantages such as good defluorination effect, simple operation, widely available and inexpensive reagents, relatively mild reaction conditions, short processing time, low cost, and process safety. Furthermore, it can prepare low-fluorine MXene materials with excellent performance, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional materials technology, specifically to a low-fluorine MXene material, its preparation method, and its application. Background Technology

[0002] MXene is a two-dimensional material with excellent electrical conductivity, abundant surface functional groups, good mechanical stability, and tunable band gap, making it promising for applications in energy storage and catalysis. Currently, the most widely used method for MXene preparation is etching with fluorinated etchants (e.g., high-concentration hydrogen fluoride solutions). However, this method inevitably introduces fluorine into the MXene surface, resulting in a fluorine content of 5wt%–25wt% (commercially available MXene products can contain up to 20wt%). The presence of fluorine not only negatively impacts the conductivity of MXene but also severely hinders electrolyte ion transport and reduces electroactive sites. This can lead to catalyst poisoning during catalysis, significantly reducing reaction performance. Furthermore, the residual hydrogen fluoride etchant on the MXene surface also has a significant impact on the environment.

[0003] Currently, the preparation methods for low-fluorine / fluorine-free MXenes mainly fall into the following two categories:

[0004] 1) Defluorination of fluorinated MXene: Mitra L. Taheri et al. defluorinated MXene by annealing it at a temperature of 500℃~700℃ (Nature Communications, 2019.10(1):p.522.). This method has a good defluorination effect, but high-temperature annealing can easily cause MXene to undergo a phase change, which will have a significant impact on the performance of MXene. CN110330020A discloses a method for defluorination of MXene using microwave as a heat source, but the microwave heating temperature needs to reach about 500℃, and the processing temperature is also very high. Xifan Chen et al. treated fluorinated MXene with n-butyllithium at a temperature of 50℃ for 10 days, which can remove about 85% of the fluorine (ACS Nano, 2019.13(8):p.9449-9456.). The defluorination effect is good, but the defluorination time of this method is long, and the reagent n-butyllithium used has certain dangers.

[0005] 2) Preparation of fluorine-free MXene using fluorine-free reagents: Di Zhang et al. prepared fluorine-free MXene using a fluorine-free medium (Angew Chem Int Ed, 2018.57(21):p.6115-6119.). However, the operating conditions of this method are quite harsh. Not only does it require the use of a NaOH solution with a concentration as high as 27.5 mol / L (a high concentration of alkaline solution), but the operating temperature also reaches 270℃. Under such operating conditions, MXene will undergo severe surface oxidation, forming byproducts TiO2, Na2Ti3O7, and Na2Ti5O. 11 This will ultimately lead to a severe decline in the conductivity, purity, and quality of MXene.

[0006] In summary, existing preparation methods cannot produce high-performance low-fluorine / fluorine-free MXene materials, which cannot fully meet the needs of practical applications and greatly limit the further expansion of MXene materials.

[0007] Therefore, it is of great significance to develop a method for preparing low-fluorine MXene materials that is simple to operate, has a short processing time, low cost, and safe process, and to prepare low-fluorine MXene materials with excellent performance. Summary of the Invention

[0008] The purpose of this invention is to provide a low-fluorine MXene material, its preparation method, and its application.

[0009] The technical solution adopted in this invention is:

[0010] A method for preparing a low-fluorine MXene material includes the following steps: mixing fluorine-containing MXene, caustic alkali, strontium salt, polyol and water for reaction, then separating the product, and washing the product with hydrochloric acid to obtain the low-fluorine MXene material.

[0011] Preferably, the mass ratio of the fluorinated MXene, caustic alkali, strontium salt, polyol, and water is 1:0.02~40:0.15~300:10~5000:1~500.

[0012] More preferably, the mass ratio of the fluorinated MXene, caustic alkali, strontium salt, polyol, and water is 1:0.6-1.2:5-20:80-600:8-60.

[0013] Preferably, the fluorinated MXene is a fluorinated Ti3C2T. x -MXene, fluorine-containing Nb2CT x At least one of -MXene.

[0014] Preferably, the caustic alkali is at least one of sodium hydroxide and potassium hydroxide.

[0015] Preferably, the strontium salt is at least one of strontium nitrate and strontium chloride.

[0016] Preferably, the polyol is at least one selected from ethylene glycol, glycerol, butanetetraol, and xylitol.

[0017] Preferably, the reaction is carried out at a temperature of 100℃ to 230℃ for a reaction time of 1h to 8h.

[0018] Preferably, the product is separated by centrifugation.

[0019] Preferably, the concentration of the hydrochloric acid is 0.5 mol / L to 9.0 mol / L.

[0020] A low-fluorine MXene material, which is prepared by the above-described method.

[0021] An MXene self-supporting membrane comprising the aforementioned low-fluorine MXene material.

[0022] The preparation method of the above-mentioned MXene self-supporting membrane includes the following steps: preparing a dispersion of low-fluorine MXene material, followed by filtration and drying to obtain the MXene self-supporting membrane.

[0023] The principle of this invention: Fluorine in fluorine-containing MXene reacts with alkaline earth metal ions Sr 2+ Compared to MXene, it has a stronger binding ability. During the reaction, fluorine-containing MXene undergoes defunctionalization of fluorine to generate SrF2 crystals (strontium salt is used to compete for and bind fluorine to generate SrF2 crystals, while caustic alkali and polyol are used to maintain the structural integrity of MXene during the reaction). SrF2 crystals are easily soluble in hydrochloric acid and can be completely washed away by hydrochloric acid, finally yielding low-fluorine MXene materials.

[0024] The beneficial effects of the present invention are: the preparation method of the low-fluorine MXene material of the present invention has the advantages of good defluorination effect, simple operation, wide availability and low price of reagents, relatively mild reaction conditions, short processing time, low cost and safe process, and can prepare low-fluorine MXene material with excellent performance, which is suitable for large-scale industrial application. Attached Figure Description

[0025] Figure 1 The fluorine-containing Ti3C2T in Example 1 x -EDS diagrams of MXene and low-fluorine MXene materials.

[0026] Figure 2 The fluorine-containing Ti3C2T in Example 1 x SEM images of MXene and low-fluorine MXene materials. Detailed Implementation

[0027] The present invention will be further explained and described below with reference to specific embodiments.

[0028] Example 1:

[0029] A low-fluorine MXene material is prepared as follows:

[0030] 1g of fluorine-containing Ti3C2T x -MXene (fluorine content 17.94wt%), 0.8g potassium hydroxide, 6g strontium nitrate, 100g ethylene glycol and 10g water were mixed evenly and added to the reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 8h. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0031] An MXene self-supporting membrane is prepared as follows:

[0032] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0033] Performance testing:

[0034] The fluorine-containing Ti3C2T in this embodiment x Energy dispersive spectroscopy (EDS) spectra of MXene and low-fluorine MXene materials are shown below. Figure 1 (a is fluorine-containing Ti3C2T) x As shown in the image (-MXene, b is a low-fluorine MXene material), the scanning electron microscope (SEM) image is as follows. Figure 2 (a is fluorine-containing Ti3C2T) x -MXene, b is a low-fluorine MXene material (as shown in the figure).

[0035] Depend on Figure 1 It can be seen that the fluorine content of the low-fluorine MXene material is only 0.92 wt%, which is far lower than that of the fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 94.87%, demonstrating excellent fluorine removal performance.

[0036] Depend on Figure 2 It can be seen that the surface of low-fluorine MXene material is smooth, unlike that of fluorine-containing Ti3C2T. x The fact that there is no significant difference in morphology compared to MXene indicates that the preparation method of the present invention does not have a significant impact on the macroscopic and microscopic morphology of the raw materials.

[0037] Example 2:

[0038] A low-fluorine MXene material is prepared as follows:

[0039] 1g of fluorine-containing Nb2CT x MXene (fluorine content 16.92wt%), 0.8g potassium hydroxide, 6g strontium nitrate, 100g ethylene glycol and 10g water were mixed evenly and added to a reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 2 hours. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0040] An MXene self-supporting membrane is prepared as follows:

[0041] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0042] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 2.15 wt% fluorine, far lower than that of fluorine-containing Nb2CT. x -MXene has a fluorine content of 16.92wt% and a fluorine removal rate of up to 87.29%, demonstrating excellent fluorine removal performance.

[0043] Example 3:

[0044] A low-fluorine MXene material is prepared as follows:

[0045] 0.02g of fluorine-containing Ti3C2T x MXene (fluorine content 17.94wt%), 0.02g sodium hydroxide, 0.15g strontium chloride, 10g glycerol and 1g water were mixed evenly and added to a reaction vessel. The mixture was then heated to 100℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 0.5mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0046] An MXene self-supporting membrane is prepared as follows:

[0047] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0048] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.23 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.14%, demonstrating excellent fluorine removal performance.

[0049] Example 4:

[0050] A low-fluorine MXene material is prepared as follows:

[0051] 0.1g of fluorine-containing Ti3C2T x MXene (fluorine content 17.94wt%), 0.08g sodium hydroxide, 0.6g strontium chloride, 20g glycerol and 1g water were mixed evenly and added to a reaction vessel. The mixture was then heated to 180℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 3.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0052] An MXene self-supporting membrane is prepared as follows:

[0053] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0054] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 0.92 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 94.87%, demonstrating excellent fluorine removal performance.

[0055] Example 5:

[0056] A low-fluorine MXene material is prepared as follows:

[0057] 0.4g of fluorine-containing Ti3C2T x -MXene (fluorine content 17.94wt%), 0.4g sodium hydroxide, 6g strontium chloride, 50g glycerol and 4g water were mixed evenly and added to the reaction vessel. The mixture was then heated to 180℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 6.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0058] An MXene self-supporting membrane is prepared as follows:

[0059] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0060] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.15 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.59%, demonstrating excellent fluorine removal performance.

[0061] Example 6:

[0062] A low-fluorine MXene material is prepared as follows:

[0063] 0.8g of fluorine-containing Ti3C2T x -MXene (fluorine content 17.94wt%), 0.6g sodium hydroxide, 6g strontium chloride, 100g glycerol and 10g water were mixed evenly and added to the reaction vessel. The mixture was then heated to 200℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0064] An MXene self-supporting membrane is prepared as follows:

[0065] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0066] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.02 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 94.31%, demonstrating excellent fluorine removal performance.

[0067] Example 7:

[0068] A low-fluorine MXene material is prepared as follows:

[0069] 0.1g of fluorine-containing Ti3C2T x MXene (fluorine content 17.94wt%), 0.08g sodium hydroxide, 0.6g strontium chloride, 20g butanethylene, and 1g water were mixed evenly and added to a reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 1 hour. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0070] An MXene self-supporting membrane is prepared as follows:

[0071] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0072] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.08 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.98%, demonstrating excellent fluorine removal performance.

[0073] Example 8:

[0074] A low-fluorine MXene material is prepared as follows:

[0075] 0.1g of fluorine-containing Ti3C2Tx MXene (fluorine content 17.94wt%), 0.08g sodium hydroxide, 0.6g strontium chloride, 20g xylitol and 1g water were mixed evenly and added to a reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 1h. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0076] An MXene self-supporting membrane is prepared as follows:

[0077] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0078] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.12 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.76%, demonstrating excellent fluorine removal performance.

[0079] Example 9:

[0080] A low-fluorine MXene material is prepared as follows:

[0081] 0.1g of fluorine-containing Ti3C2T x -MXene (fluorine content 17.94wt%), 0.08g potassium hydroxide, 0.8g strontium chloride, 10g ethylene glycol and 1g water were mixed evenly and added to the reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0082] An MXene self-supporting membrane is prepared as follows:

[0083] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0084] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.11 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.81%, demonstrating excellent fluorine removal performance.

[0085] Example 10:

[0086] A low-fluorine MXene material is prepared as follows:

[0087] 0.1g of fluorine-containing Ti3C2T x-MXene (fluorine content 17.94wt%), 0.08g potassium hydroxide, 0.8g strontium nitrate, 10g ethylene glycol and 1g water were mixed evenly and added to the reaction vessel. The mixture was then heated to 230℃ and reacted at a constant temperature for 3h. After centrifugation, the suspension was washed with 9.0mol / L hydrochloric acid to obtain low-fluorine MXene material (dispersion).

[0088] An MXene self-supporting membrane is prepared as follows:

[0089] The above-mentioned low-fluorine MXene material was filtered and then dried to obtain an MXene self-supporting membrane.

[0090] Tests (using the same method as in Example 1) showed that the low-fluorine MXene material in this example contained only 1.08 wt% fluorine, far lower than that of fluorine-containing Ti3C2T. x -MXene has a fluorine content of 17.94wt% and a fluorine removal rate of up to 93.98%, demonstrating excellent fluorine removal performance.

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-fluorine MXene material, characterized in that, Includes the following steps: Fluorinated MXene, caustic alkali, strontium salt, polyol, and water are mixed and reacted, followed by product separation. The product is then washed with hydrochloric acid to obtain low-fluorinated MXene material. The mass ratio of the fluorinated MXene, caustic alkali, strontium salt, polyol, and water is 1:0.02–40:0.15–300:10–5000:1–500. The polyol is at least one selected from ethylene glycol, glycerol, butanetetraol, and xylitol. The reaction is carried out at a temperature of 100℃–230℃ for 1–8 hours.

2. The method for preparing the low-fluorine MXene material according to claim 1, characterized in that: The caustic alkali is at least one of sodium hydroxide and potassium hydroxide.

3. The method for preparing the low-fluorine MXene material according to claim 1, characterized in that: The strontium salt is at least one of strontium nitrate and strontium chloride.

4. The method for preparing the low-fluorine MXene material according to claim 1, characterized in that: The concentration of the hydrochloric acid is 0.5 mol / L to 9.0 mol / L.

5. A low-fluorine MXene material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 4.

6. An MXene self-supporting membrane, characterized in that, It includes the low-fluorine MXene material as described in claim 5.

Images