A desalination electrode material, and a preparation method and application thereof

Abstract

The application provides a desalination electrode material and a preparation method and application thereof. The preparation method comprises the following steps: S1, providing a two-dimensional material with a chemical formula of Ti3C2T X ; S2, ultrasonic dispersing the two-dimensional material in a water body to obtain a dispersion liquid; S3, performing first mixing treatment on the dispersion liquid and copper sulfate to obtain a pretreatment liquid; S4, performing second mixing treatment on the pretreatment liquid and sodium borohydride to obtain a reaction liquid; and S4, performing centrifugal treatment on the reaction liquid, and performing vacuum freeze drying on a solid product obtained through the centrifugal treatment to obtain the electrode material. The application belongs to the first application of a prepared copper-based electrode material in the desalination field, and effectively improves the desalination efficiency.

Description

Technical Field

[0001] This invention relates to electrochemical desalination, and more particularly to a desalination electrode material, its preparation method, and its application. Background Technology

[0002] Seawater desalination is an important means of solving the problem of freshwater shortage and promoting sustainable economic and social development.

[0003] Capacitive deionization (CDI) is a low-energy, low-cost seawater desalination technology and a hot topic in ecological and environmental science. Traditional CDI electrode materials rely solely on non-Laday double-layer capacitance to store ions, and the limited polarizable specific surface area of ​​the electrode materials restricts the seawater desalination capacity of CDI. Desalination batteries proposed after 2012 address this issue, where the Na+... + and Cl - The removal is achieved by forming chemical bonds and embedding the Na into the electrode. During the charging process, Na is embedded into the electrode material. + and Cl - The deintercalation and release into the solution significantly improves the desalination performance.

[0004] For desalination batteries, the type of cathode and anode electrode materials has a significant impact on desalination performance. Sodium-ion storage electrodes have been extensively studied with the development of sodium-ion batteries. However, for chloride-ion storage electrodes, there are currently only a few reports, which limits further improvements in the performance of desalination batteries.

[0005] Therefore, it is necessary to provide a desalination electrode material, its preparation method and application, in order to solve or at least alleviate the technical defects of the existing electrode materials in terms of low desalination effect. Summary of the Invention

[0006] The main objective of this invention is to provide a desalination electrode material, its preparation method, and its application, aiming to solve the technical problem of low desalination effect of existing electrode materials.

[0007] To achieve the above objectives, the present invention provides a method for preparing a desalination electrode material, comprising the following steps:

[0008] S1, provided with the chemical formula Ti3C2T X Two-dimensional materials;

[0009] S2, the two-dimensional material is ultrasonically dispersed in water to obtain a dispersion;

[0010] The solid-liquid ratio of the two-dimensional material to the water is 2-3 mg: 1 ml;

[0011] S3, the dispersion and copper sulfate are subjected to a first mixing treatment to obtain a pretreated solution;

[0012] S4, the pretreatment solution and sodium borohydride are subjected to a second mixing treatment to obtain a reaction solution;

[0013] The mass ratio of the two-dimensional material, the copper sulfate, and the sodium borohydride is 1:1.5 to 2:1 to 2.

[0014] S4, the reaction solution is centrifuged, and the solid product obtained by centrifugation is freeze-dried under vacuum to obtain the electrode material.

[0015] Furthermore, the synthesis process of the two-dimensional material includes the following steps:

[0016] S11, LiF is added to HCl solution and then stirred to obtain the first treatment solution;

[0017] The solid-liquid ratio of the LiF and the HCl solution is 1-3 g: 60 mL, and the concentration of the HCl solution is 6-12 mol / L.

[0018] S12, Ti3AlC2 is added to the first treatment solution, and then reacted at 35-45°C for 24-48 hours to obtain the second treatment solution;

[0019] The mass ratio of Ti3AlC2 to LiF is 2:1 to 2;

[0020] S13, perform solid-liquid separation treatment on the second processing liquid to obtain the two-dimensional material.

[0021] Furthermore, the power of the ultrasound is 200-700W, and the duration of the ultrasound is 1-15s.

[0022] Further, the first mixing process includes: adding the copper sulfate to the dispersion under stirring conditions; and continuing to stir the dispersion for 0 to 4 hours after the copper sulfate has completely dissolved in the dispersion.

[0023] Further, the second mixing process includes: adding the sodium borohydride to the pretreatment solution, and then stirring the pretreatment solution for 0.5 to 2 hours.

[0024] Furthermore, the centrifugation speed is 5000-7000 rpm; the centrifugation time is 1-15 min.

[0025] Furthermore, the vacuum freeze-drying time is 8 to 15 hours.

[0026] The present invention also provides a desalination electrode material, which is prepared by any of the preparation methods described above.

[0027] The present invention also provides an application of the desalination electrode material as described above in capacitive deionization.

[0028] The present invention also provides a method for capacitive deionization, which uses a capacitive deionization device to desalinate a sodium chloride-containing salt solution; wherein, the anode of the capacitive deionization device is loaded with any of the desalination electrode materials described above, and the cathode of the capacitive deionization device is loaded with activated carbon material.

[0029] Before the desalting process, nitrogen gas is introduced into the salt solution;

[0030] During the desalination process, a voltage of 1.2 to 1.4V is applied to the capacitive deionization device.

[0031] Compared with the prior art, the present invention has at least the following advantages:

[0032] 1. This invention prepares a desalination electrode material based on MXene / Cu, which is the first time that the prepared copper-based electrode material has been applied to the field of desalination.

[0033] 2. This invention uses a Cu electrode, where Cu and Cl... - The combination pathway is stable and reversible; the desalination process involving Cu mainly occurs through the reaction of Cu and Cl. - By combining the specific formation of Cu2(OH)3Cl precipitate, the removal of Cl is achieved. - This effectively improves the desalination effect and efficiency.

[0034] 3. The present invention uses MXene as the substrate material, which can effectively enhance the stability of Cu and contribute desalination capability through the mechanism of pseudocapacitance.

[0035] 4. The preparation method of the present invention uses simple equipment and the process is simple and easy to implement. It can be operated continuously, thus making it suitable for large-scale production.

[0036] 5. The desalination electrode material of the present invention combines the pseudocapacitance and redox reaction mechanism of Faraday electrode material, which can synergistically contribute to high desalination capacity and fast desalination rate. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0038] Figure 1 The XRD comparison diagrams of the electrode materials in Example 2 (5s) and Comparative Example 1 (60s) of the present invention are shown.

[0039] Figure 2 The images show a comparison of the XRD patterns of the electrode materials in Example 2 (1:0.75) and Comparative Example 2 (1:1.5) of this invention.

[0040] Figure 3 This is a comparison chart of the desalination effects of the electrode materials in Examples 2 (0h), 3 (4h), and Comparative Example 3 (8h) of the present invention;

[0041] Figure 4 This is a comparison chart of the desalination effects of the electrode materials in Example 2 (5000 rpm), Example 4 (7000 rpm), and Comparative Example 4 (10000 rpm) of the present invention;

[0042] Figure 5 This is a comparison diagram of the desalination effect under different voltages in Example 6 of the present invention;

[0043] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0046] It should be noted that the two-dimensional material MXene has a layered structure similar to graphene, which can effectively buffer the mechanical stress generated during ion insertion / extraction and enhance the cycling stability of the electrode; Cu is more inexpensive and more practical; Cu has a larger theoretical specific capacity (418 mAh g). –1 It is easier to achieve efficient desalination; Cu and its conversion products have good conductivity and tolerance, which meet the requirements of desalination batteries.

[0047] Currently, MXene / Cu materials have been successfully prepared. For example, the paper "Electrocatalytic Synthesis of Ammonia Using a 2D Ti3C2 MXene Loaded with Copper Nanoparticles" prepared a Cu / Ti3C2 composite catalyst. This catalyst has good selectivity under environmental conditions and can effectively electrochemically convert N2 into NH3. However, the Cu / Ti3C2 prepared by this method is mainly used in the field of catalysis, and its performance in the direct application of desalination is very poor.

[0048] Therefore, the present invention provides a method for preparing a desalination electrode material, comprising the following steps:

[0049] S1, provided with the chemical formula Ti3C2T x Two-dimensional materials.

[0050] The two-dimensional material is a type of MXene, specifically MXene freeze-dried powder.

[0051] The synthesis process of the two-dimensional material may include the following steps:

[0052] S11, add LiF to the HCl solution and stir for 20-50 minutes at a speed of 300-600 rpm to obtain the first treatment solution.

[0053] The solid-liquid ratio of the LiF and the HCl solution is 1-3 g: 60 mL, and the concentration of the HCl solution is 6-12 mol / L.

[0054] S12, add Ti3AlC2 (which can pass through a 400-mesh sieve) to the first treatment solution (it can be added slowly in multiple batches), and then react at 35-45℃ (it can be carried out under stirring, and the speed can be 300-600 rpm) for 24-48 hours to obtain the second treatment solution.

[0055] The mass ratio of Ti3AlC2 to LiF is 2:1 to 2.

[0056] S13, perform solid-liquid separation treatment on the second processing liquid (which may be centrifugation) to obtain the two-dimensional material; wherein, after the solid-liquid separation treatment, the solid product of the solid-liquid separation treatment may be washed with deionized water, sonicated, and freeze-dried in sequence to obtain Ti3C2Tx powder (MXene freeze-dried powder).

[0057] S2, the two-dimensional material is ultrasonically dispersed in water to obtain a dispersion.

[0058] The solid-liquid ratio of the two-dimensional material to the water is 2-3 mg: 1 ml.

[0059] The ultrasonic power is 200–700W, and the duration of the ultrasonic wave is 1–15s. By controlling the duration of the ultrasonic wave, the crystal structure of the electrode material can be further improved, thereby ensuring the desalination performance of the electrode material.

[0060] S3, the dispersion and copper sulfate are subjected to a first mixing treatment to obtain a pretreated solution.

[0061] The copper sulfate may be copper sulfate pentahydrate.

[0062] The first mixing process may include: adding copper sulfate to the dispersion under stirring conditions, and continuing to stir the dispersion for 0 to 4 hours after the copper sulfate has completely dissolved in the dispersion.

[0063] In particular, by controlling the duration of continued stirring of the dispersion, the desalination performance of the electrode material can be further improved.

[0064] S4, the pretreatment solution and sodium borohydride are subjected to a second mixing treatment to obtain a reaction solution.

[0065] The mass ratio of the two-dimensional material, the copper sulfate, and the sodium borohydride is 1:1.5 to 2:1 to 2.0. By controlling the above mass ratio, the preparation of the electrode material can be guaranteed, and the desalination performance of the electrode material can be improved.

[0066] The second mixing process may include or consist of adding the sodium borohydride to the pretreatment solution and then stirring the pretreatment solution for 0.5 to 2 hours to promote a complete reaction.

[0067] S4, the reaction solution is centrifuged, and the solid product obtained by centrifugation is freeze-dried under vacuum to obtain the electrode material.

[0068] The centrifugation speed can be 5000-7000 rpm; the centrifugation time can be 1-15 min; by controlling the centrifugation speed, the desalination performance of the electrode material can be ensured.

[0069] The cold well temperature for the vacuum freeze-drying can be -40 to -80°C, and the duration of the vacuum freeze-drying can be 8 to 15 hours. By performing the vacuum freeze-drying, electrode material products can be obtained.

[0070] The present invention also provides a desalination electrode material, which is prepared by the preparation method described in any of the above embodiments.

[0071] This invention also provides an application of the desalination electrode material as described in any of the above embodiments in capacitive deionization desalination, wherein the desalination solution can be a salt solution, preferably a chloride ion solution, specifically a sodium chloride solution. In the salt solution of this invention, the concentration of chloride ions can be 800-2000 mg / L.

[0072] In practical applications, this invention also provides a capacitive deionization method for desalting sodium chloride-containing salt solutions, using a capacitive deionization device to remove chloride ions from the salt solution. The anode of the capacitive deionization device is loaded with the desalting electrode material described in any of the above embodiments, and the cathode of the capacitive deionization device is loaded with the activated carbon material. Both the current collectors for the anode and the cathode can be inert materials; in the embodiments of this invention, both the current collectors for the anode and the cathode are titanium plates.

[0073] Before the desalting process, nitrogen gas can be introduced into the salt solution for 15 to 30 minutes to prevent dissolved oxygen in the salt solution from affecting the active material on the electrode.

[0074] During the desalination process, a voltage of 1.2 to 1.4V is applied to the capacitor deionization device to ensure efficient desalination.

[0075] To facilitate a detailed understanding of the present invention by those skilled in the art, the following examples are provided:

[0076] Example 1

[0077] The following steps are used to synthesize the chemical formula Ti3C2T x Two-dimensional material MXene:

[0078] 1. Add 2g LiF to 60mL 9mol / L HCl, stir for 30min at 450 rpm to obtain the first treatment solution;

[0079] 2. Slowly add 2g of Ti3AlC2 (400 mesh) to the first treatment solution in multiple batches, and react with stirring at a temperature of 40℃ and a speed of 350 rpm for 48 hours to obtain the second treatment solution.

[0080] 3. The second treatment liquid was centrifuged (5000 rpm), washed with deionized water, sonicated (sonication power of 700W, liquid environment of deionized water), and freeze-dried (cold well temperature of -40℃) to obtain Ti3C2Tx powder (MXene freeze-dried powder); among which, according to XRD diffraction peak analysis, the diffraction peak of Al disappeared.

[0081] Example 2

[0082] The electrode material is prepared using the following steps:

[0083] 1. 50 mg of MXene lyophilized powder (from Example 1) was sonicated in 20 ml of pure water to disperse it evenly, thus obtaining a dispersion; wherein, the sonication power was 700 W and the duration was 5 s.

[0084] 2. Add 80 mg CuSO4·5H2O to the dispersion and stir until CuSO4·5H2O is completely dissolved. Then immediately add 60 mg NaBH4 to the dispersion and stir for 1 hour to obtain the reaction solution.

[0085] 3. Centrifuge the reaction solution at 5000 rpm for 1 min to obtain a solid product;

[0086] 4. The solid product is subjected to vacuum freeze-drying to obtain electrode material (MXene / Cu); wherein the cold well temperature of vacuum freeze-drying is -40℃ and the duration is 12h.

[0087] Comparative Example 1

[0088] Compared to Example 2, this comparative example adjusted the ultrasound duration to 60 seconds, while keeping other conditions the same as in Example 2, to prepare the electrode material.

[0089] See Figure 1 As shown, the XRD of the electrode material in Example 2 corresponds to 5s, while the XRD of the electrode material in this comparative example corresponds to 60s.

[0090] Depend on Figure 1 It can be seen that the MXene / Cu material prepared by uniformly dispersing MXene freeze-dried powder by ultrasound for 5s exhibits more peaks, indicating that MXene has a better crystal form and the 002 peak is stronger; based on this, the ultrasound time can be selected from 1 to 15s.

[0091] Comparative Example 2

[0092] Compared to Example 2, the mass ratio of CuSO4·5H2O and NaBH4 in this comparative example was adjusted to 1:1.5, that is, the amount of CuSO4·5H2O was 80 mg and the amount of NaBH4 was 120 mg; other conditions remained the same as in Example 2, and the electrode material was prepared.

[0093] See Figure 2 As shown, the XRD ratio of the electrode material in Example 2 is 1:0.75, while the XRD ratio of the electrode material in this comparative example is 1:1.5.

[0094] Depend on Figure 2 It can be seen that when the mass ratio of CuSO4·5H2O to NaBH4 is 1:0.75, the (111), (200), and (220) peak intensities of Cu in the prepared MXene / Cu material are greater, indicating that the material has a better crystal structure.

[0095] Example 3

[0096] Compared to Example 2, in this embodiment, after CuSO4·5H2O is completely dissolved, the dispersion is stirred for another 4 hours, and then NaBH4 is added to the dispersion. Other conditions are kept the same as in Example 2 to prepare the electrode material.

[0097] Comparative Example 3

[0098] Compared to Example 2, in this comparative example, after CuSO4·5H2O was completely dissolved, the dispersion was stirred for another 8 hours, and then NaBH4 was added to the dispersion. Other conditions remained the same as in Example 2, and the electrode material was prepared.

[0099] Example 4

[0100] Compared to Example 2, this embodiment sets the centrifugation speed to 7000 rpm, while keeping other conditions the same as in Example 2, to prepare the electrode material.

[0101] Comparative Example 4

[0102] Compared to Example 2, this embodiment sets the centrifugation speed to 10,000 rpm, while keeping other conditions the same as in Example 2, to prepare the electrode material.

[0103] Comparative Example 5

[0104] The electrode material in this comparative example was prepared using the method described in "Electrocatalytic Synthesis of Ammonia Using a 2DTi3C2MXene Loaded with Copper Nanoparticles".

[0105] The specific steps are as follows:

[0106] 1. Add 100 mg of Ti3C2 to 20 mL of ethylene glycol and stir at room temperature for 2 hours to obtain a mixed solution;

[0107] 2. Add 46.1 mg Cu(NO3)2·3H2O to the mixed solution and continue stirring for 12 h to obtain the first reaction solution;

[0108] 3. Under the conditions of 0℃ and stirring, add 75.7 mg NaBH4 to the first reaction solution and continue stirring for 12 h to obtain the second reaction solution;

[0109] 4. Centrifuge the second reaction solution, and then wash the precipitate two to three times with deionized water;

[0110] 5. The washed product was vacuum dried at 60℃ for 12 hours to obtain the product Cu / Ti3C2 (as an electrode material).

[0111] Example 5

[0112] The electrode materials prepared in Examples 2, 3, 4, 3, 4, 5, and 5 were used as test materials for desalination tests, and the adsorption effect of the test materials on chloride ions was analyzed.

[0113] The specific experimental procedure is as follows:

[0114] 1. Preparation of salt solution: Weigh 1.000g NaCl and dissolve it in a beaker, then transfer it to a 1L volumetric flask and make up to volume.

[0115] The initial concentration of NaCl in the salt solution is 1000 mg / L; the initial pH of the salt solution is 6.

[0116] 2. Preparation of anode: Weigh 40mg of the material to be tested, 5mg of conductive carbon black, and 5mg of polyvinylidene fluoride binder, transfer them to a mortar and grind them evenly. Add 200μL of N-methylpyrrolidone to prepare a slurry, then coat it on one side to a 6cm*6cm current collector and dry it under vacuum at 50℃ for 12 hours.

[0117] 3. Preparation of cathode: Weigh 40mg of activated carbon, 5mg of conductive carbon black, and 5mg of polyvinylidene fluoride binder, transfer them to a mortar and grind them evenly. Add 200μL of N-methylpyrrolidone to prepare a slurry, then coat it on one side to a 6cm*6cm current collector and dry it under vacuum at 50℃ for 12 hours.

[0118] 4. Install the above-mentioned anode (coated side facing the cathode) and cathode (coated side facing the anode) in the capacitor deionization device, add 40 ml of the above-mentioned salt solution to the capacitor deionization device; then purge nitrogen gas into the salt solution for 30 min.

[0119] During desalination, the nitrogen gas supply is stopped, and then a voltage of 1.2V is continuously applied to the capacitor deionization unit.

[0120] Experimental results:

[0121] See Figure 3 As shown, the desalination effect of the electrode material in Example 2 corresponds to 0h, the desalination effect of the electrode material in Example 3 corresponds to 4h, and the desalination effect of the electrode material in Comparative Example 3 corresponds to 8h.

[0122] Depend on Figure 3 It can be seen that different stirring times after adding CuSO4·5H2O have a significant impact on the removal efficiency of the material. Specifically, the electrode materials prepared after stirring for 0 h, 4 h, and 8 h were used for desalination. After 1 h of desalination, the equilibrium adsorption capacity was 79.22 mg g, respectively. -1 72.83mg g -1 55.09mg g -1 This indicates that the longer the stirring time, the worse the effect; NaBH4 should be added immediately after CuSO4·5H2O.

[0123] See Figure 4 As shown, the desalination effect of the electrode material in Example 2 corresponds to 5000 rpm, the desalination effect of the electrode material in Example 4 corresponds to 7000 rpm, and the desalination effect of the electrode material in Comparative Example 4 corresponds to 10000 rpm.

[0124] Depend on Figure 4 It can be seen that the removal effect of electrode materials prepared at different centrifugation speeds is significantly different. Materials prepared at centrifugation speeds of 5000 rpm, 7000 rpm, and 10000 rpm were used for desalination. After 1 hour of desalination, the equilibrium adsorption capacity was 80.2 mg g, respectively. -1 72.8mg g -1 44.5mg g -1 Therefore, materials prepared by centrifugation at 5000-7000 rpm have good desalination performance.

[0125] Note: When comparing centrifugal forces, the electrode material corresponding to 5000 rpm was re-prepared (Example 2) to keep it in the same batch as the electrode materials corresponding to 7000 rpm and 10000 rpm, thereby reducing experimental error; therefore, the adsorption amount corresponding to Example 2 will have slight fluctuations, which are within the normal fluctuation range.

[0126] Furthermore, the electrode materials prepared in Example 2 and Comparative Example 5 were compared: after 1 hour of desalting, the equilibrium adsorption capacity of the electrode material in Example 2 was 79.22 mg g. -1 The equilibrium adsorption capacity of the electrode material in Comparative Example 5 was 50.5 mg g. -1 In Example 2, the desalination rate and desalination capacity of the electrode material are significantly better than those of the electrode material in Comparative Example 5. This is because the electrode materials reported in the literature are mainly used in the field of catalysis and are not suitable for the field of desalination, while the electrode material prepared by the present invention is more suitable for desalination systems and has a good desalination effect.

[0127] Example 6

[0128] Compared to Example 5, this embodiment limits the test material to the electrode material prepared in Example 2, and sets the voltage to 0.6V, 0.8V, 1.0V, and 1.4V respectively (each voltage is a separate test). Other conditions are the same as in Example 5, in order to analyze the effect of different voltages on the test results.

[0129] Experimental results:

[0130] See Figure 5 As shown, when the voltages are 0.6V, 0.8V, 1.0V, and 1.4V, the equilibrium adsorption capacities after 1 hour of desalination are 16.6mg / g, 39.7mg / g, 79.3mg / g, and 81.4mg / g, respectively.

[0131] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. The application of a desalination electrode material in capacitive deionization, characterized in that, A capacitive deionization device is used to desalinate a sodium chloride-containing salt solution; the anode of the capacitive deionization device is loaded with the desalination electrode material, and the cathode of the capacitive deionization device is loaded with activated carbon material. The preparation method of the desalination electrode material includes the following steps: S1, provided with the chemical formula Ti3C2T X Two-dimensional materials; S2, the two-dimensional material is ultrasonically dispersed in water to obtain a dispersion; The solid-liquid ratio of the two-dimensional material and the water is 2~3 mg:1 ml; the power of the ultrasound is 200~700 W, and the duration of the ultrasound is 1~15 s; S3, the dispersion and copper sulfate are subjected to a first mixing treatment to obtain a pretreated solution; The first mixing process includes: adding the copper sulfate to the dispersion under stirring conditions; and continuing to stir the dispersion for 0 to 4 hours after the copper sulfate has completely dissolved in the dispersion. S4, the pretreatment solution and sodium borohydride are subjected to a second mixing treatment to obtain a reaction solution; The mass ratio of the two-dimensional material, the copper sulfate, and the sodium borohydride is 1:1.5~2:1~2; S4, the reaction solution is centrifuged, and the solid product obtained by centrifugation is freeze-dried under vacuum to obtain the desalted electrode material; the centrifugation speed is 5000~7000 rpm; the centrifugation time is 1~15 min.

2. The application according to claim 1, characterized in that, The synthesis process of the two-dimensional material includes the following steps: S11, LiF is added to HCl solution and then stirred to obtain the first treatment solution; The solid-liquid ratio of the LiF and the HCl solution is 1~3 g:60 mL, and the concentration of the HCl solution is 6~12 mol / L; S12, Ti3AlC2 is added to the first treatment solution, and then reacted at 35~45℃ for 24~48 hours to obtain the second treatment solution; The mass ratio of Ti3AlC2 to LiF is 2:1~2; S13, perform solid-liquid separation treatment on the second processing liquid to obtain the two-dimensional material.

3. The application according to claim 1, characterized in that, The second mixing process includes: adding the sodium borohydride to the pretreatment solution, and then stirring the pretreatment solution for 0.5 to 2 hours.

4. The application according to claim 1, characterized in that, The vacuum freeze-drying time is 8-15 hours.

5. The application according to claim 1, characterized in that, Before the desalting process, nitrogen gas is introduced into the salt solution; during the desalting process, a voltage of 1.2 to 1.4 V is applied to the capacitive deionization device.

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