Bimetallic organic framework electrode material based on co-crystal solvent and preparation method and application thereof

Abstract

The application relates to the technical field of water treatment, in particular to a double-metal organic framework electrode material based on a eutectic solvent and a preparation method and application thereof, wherein the eutectic solvent is mixed with water to obtain a mixed solvent; soluble iron salt and soluble nickel salt are added into the mixed solvent, active carbon powder and a dispersing agent are added after ultrasonic dissolution, ultrasonic mixing is carried out, 2-methyl imidazole is added, and a mixed solution is obtained; the mixed solution is subjected to water bath reaction, and post-treatment is carried out on the water bath reaction product to obtain a double-metal organic framework active carbon composite material; the double-metal organic framework composite material is used as electrode active material and is mixed with a conductive agent and a binder to obtain electrode slurry; the electrode slurry is coated on an electrode plate, and after drying, a double-metal organic framework active carbon composite electrode material is obtained; the double-metal organic framework active carbon composite electrode material is generated by using the eutectic solvent, is applied to a hybrid capacitive deionization device, and is used for removing salt ions in water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a double-metal organic framework electrode material based on a eutectic solvent and a preparation method and application thereof. BACKGROUND

[0002] Capacitive deionization (CDI) is a new type of brackish water desalination technology, which is gradually becoming an effective alternative to traditional desalination methods due to its environmental friendliness, low energy consumption, low cost, high regeneration efficiency, and no secondary pollution. CDI technology is based on the double-layer physical adsorption theory, which drives the charged ions in the solution to migrate to the porous electrode and form a double-layer adsorption by applying a directional electrostatic field. When the electrode adsorption is close to saturation, ion rapid desorption is achieved by potential reversal or short-circuit operation, forming a cyclic ion adsorption and desorption process.

[0003] In the CDI system, the specific surface area, electrical conductivity, and ion transport channel of the electrode material are key factors that determine the desalination performance. Metal-organic framework materials (MOFs) have great potential in building efficient ion adsorption interfaces due to their unique topological structure, such as high specific surface area, adjustable pore size system, and abundant metal active sites. In particular, double-metal MOFs can induce the formation of lattice defects through the synergistic effect of heterogeneous metal centers, significantly increasing the concentration of coordination unsaturated sites, and improving the charge transport efficiency through double-metal electronic coupling effect. When combined with carbon-based materials (such as activated carbon, graphene), double-metal MOFs can not only maintain a multi-level pore structure, but also form a chemical bonding interface with the carbon-based body, realizing the dual-channel cooperative transport of electrons and ions.

[0004] The existing technology with the publication number CN116177690A discloses a method for removing fluoride ions in water using a polypyrrole / double-metal MOF / graphite composite electrode capacitive deionization. The invention uses an organic solvent as a ligand solution, and the resulting electrode material has low efficiency in removing fluoride ions from water. The generation method is a high-temperature hydrothermal method, which has certain safety risks during the generation process. SUMMARY

[0005] To overcome the shortcomings of the above-mentioned prior art, the present application provides a double-metal organic framework electrode material based on a eutectic solvent and a preparation method and application thereof. The present application uses a eutectic solvent to generate a iron-nickel double-metal composite carbon capacitive deionization electrode material, and applies it to a hybrid capacitive deionization device to remove salt ions in water.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] A preparation method of a double-metal organic framework electrode material based on a eutectic solvent, comprising the following steps:

[0008] Mixing the eutectic solvent with water to obtain a mixed solvent.

[0009] Taking the mixed solvent containing the eutectic solvent and water as a ligand solution, adding soluble iron salt and soluble nickel salt into the mixed solvent, adding activated carbon powder and a dispersing agent after ultrasonic dissolution, ultrasonic mixing, and then adding 2-methylimidazole ligand to obtain a double-metal organic framework activated carbon composite precursor solution.

[0010] Carrying out water bath reaction on the double-metal organic framework activated carbon composite precursor solution, and carrying out post-treatment on the water bath reaction product to obtain a double-metal organic framework activated carbon composite material.

[0011] Taking the double-metal organic framework composite material as an electrode active material, mixing the double-metal organic framework composite material with a conductive agent and a binder to obtain an electrode slurry, coating the electrode slurry on an electrode plate, and drying to obtain a double-metal organic framework activated carbon composite electrode material.

[0012] In the preparation process of the double-metal organic framework activated carbon composite material, the mixed solvent of the eutectic solvent and water is taken as the ligand solution, and in the synthesis process, the eutectic solvent not only acts as a solvent, but also acts as a structure directing agent. The components in the eutectic solvent, such as chloride ions and choline ions, can coordinate with metal ions, act as templates or ligands to guide the formation of pores, control the pore structure of MOFs, and enhance the adsorption and separation performance. The chloride ions in the eutectic solvent or the ammonia produced by decomposition can act as a structure directing agent, affect the coordination mode of the metal nodes, and thus control the pore size and porosity, so that the salt ions in water can be efficiently removed.

[0013] In the preferred embodiment of the present application, the eutectic solvent is composed of a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, the hydrogen bond donor is urea, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1.5-2.5.

[0014] In the preferred embodiment of the present application, the volume ratio of the eutectic solvent to water is 20:3-5.

[0015] In the preferred embodiment of the present application, the dosage ratio of iron element in the soluble iron salt, nickel element in the soluble nickel salt, and the mixed solvent is 1 mol:3 mol:46 mL-50 mL.

[0016] In the preferred embodiment of the present application, the dosage ratio of the activated carbon powder to the mixed solvent is 1.5 g-2.5 g:46 mL-50 mL, and the mass fraction of the dispersing agent in the soluble iron salt and the soluble nickel salt is 15%-25%.

[0017] In a preferred embodiment of the present application, the water bath reaction temperature is 60-80℃, and the reaction time is 10-12 h.

[0018] In a preferred embodiment of the present application, the mass ratio of the iron-nickel bimetallic organic framework activated carbon composite material, the conductive agent and the binder is 80-90: 5-10: 5-10.

[0019] Another object of the present application is to provide a eutectic solvent-based bimetallic organic framework electrode material prepared by the preparation method described in any one of the above.

[0020] A third object of the present application is to provide the use of the eutectic solvent-based bimetallic organic framework electrode material described above in a hybrid capacitive deionization device, which applies the eutectic solvent-based bimetallic organic framework electrode material to the hybrid capacitive deionization device to remove salt ions in water.

[0021] In a preferred embodiment of the present application, a hybrid capacitive deionization module is assembled with asymmetric electrodes, the anode is the eutectic solvent-based bimetallic organic framework electrode material described above, and the cathode is an activated carbon electrode, and cation exchange membranes and anion exchange membranes are arranged in front of the anode and cathode plates.

[0022] In the prior art, the electrode materials of the capacitive deionization device are the same for the anode and the cathode, while the electrode materials of the hybrid capacitive deionization device are different for the anode and the cathode, which can more fully exert the adsorption capacity of different materials for anions and cations. In the present application, the iron-nickel bimetallic organic framework activated carbon composite material has strong electric adsorption capacity for anions, but its adsorption capacity for cations is not as good as that of the activated carbon electrode, so the composite material is used as an anode material to adsorb anions, and the activated carbon material is used as a cathode to adsorb cations, which is more conducive to the adsorption of salt ions.

[0023] Deep eutectic solvents (DESs) as a new green solvent have shown significant advantages in the preparation of metal-organic frameworks (MOFs). They are composed of hydrogen bond donors and acceptors, with low toxicity, low volatility and high thermal stability, reducing environmental pollution and experimental safety risks. By adjusting the components, the physical and chemical properties can be controlled, forming a unique hydrogen bond network, affecting the melting point, viscosity and solubility of the solvent. In the synthesis of MOFs, DESs not only act as solvents, but also as structure directing agents, regulating the pore structure of MOFs and enhancing their adsorption and separation performance. In addition, DESs are easy to obtain, low in cost and simple to operate, and have good thermal and chemical stability, providing a stable environment for synthesis, so that large-scale synthesis of MOFs materials can be realized. These characteristics make DESs have broad application prospects in the synthesis of MOFs materials, and compared with traditional chemical solvents, they can bring more innovative possibilities and practical application value.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention uses a mixture of eutectic solvent and water as a mixed solvent, adds soluble iron salt and soluble nickel salt to the mixed solvent, adds activated carbon powder and dispersant after ultrasonic dissolution, ultrasonically mixes, and then adds 2-methylimidazole to obtain an iron-nickel bimetallic organic framework activated carbon composite material precursor solution; the iron-nickel bimetallic organic framework activated carbon composite material precursor solution is reacted in a water bath to obtain an iron-nickel bimetallic organic framework activated carbon composite material, which is then mixed with a conductive agent and a binder to obtain an electrode slurry, and the electrode slurry is coated on an electrode plate to obtain an iron-nickel bimetallic organic framework activated carbon composite electrode material. In the preparation process of the iron-nickel bimetallic organic framework activated carbon composite material of the present invention, a mixed solvent of a eutectic solvent and water is used as a ligand solution. During the synthesis process, the eutectic solvent serves not only as a solvent but also as a structure-directing agent. Components in the eutectic solvent, such as chloride ions and choline ions, can coordinate with metal ions and act as templates or ligands to guide pore formation, regulate the pore structure of MOFs, and enhance their adsorption and separation properties. The chloride ions in the eutectic solvent or the ammonia produced by decomposition can serve as structure-directing agents to affect the coordination mode of metal nodes, thereby regulating the pore size and porosity, and achieving efficient removal of salt ions in water.

[0026] 2. The raw materials of the eutectic solvent used in the present invention are easily available, low in cost, simple to operate, and have good thermal and chemical stability, providing a stable environment for synthesis, thereby enabling the large-scale synthesis of iron-nickel bimetallic organic framework activated carbon composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a simplified diagram of the structure of the capacitive deionization technology module of the present invention, wherein 1 is a glass plate, 2 is a silicone gasket, 3 is a current collector, 4 is an ion exchange membrane, 5 is a hollow silicone gasket, 6 is a plastic gasket, and 7 is an electrode coating.

[0028] Figure 2 This is the SEM image of the DES-MOF powder prepared in Example 1 of the present invention.

[0029] Figure 3 This is a comparison chart of the decrease in activated carbon salt solution concentration of the DES-MOF prepared in Example 1 of the present invention and that of Comparative Example 1.

[0030] Figure 4 This is a comparison chart of the desalination capacity of DES-MOF and activated carbon prepared in Example 1 of the present invention.

[0031] Figure 5 This is a diagram showing the effect of capacitive desalination in the electrode cycle test of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely in the following in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0033] It should be noted that all the professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the scope of protection of the present application. Unless otherwise specified, all the materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing methods.

[0034] Embodiment 1

[0035] A preparation method of a Fe-Ni bimetallic organic framework activated carbon composite electrode material, comprising the following steps:

[0036] (1) Preparation of eutectic solvent

[0037] The eutectic solvent is configured by selecting choline chloride as a hydrogen bond acceptor and urea as a hydrogen bond donor. 27.928 g of choline chloride and 24.024 g of urea are weighed, and the choline chloride and urea are mixed in a molar ratio of 1:2, heated and stirred in a 80 ℃ water bath, until a uniform transparent liquid is obtained, and then the eutectic solvent mixture is cooled to room temperature. Due to the low melting point property of the eutectic solvent, even at room temperature, the eutectic solvent remains in a liquid state.

[0038] (2) Preparation of Fe-Ni bimetallic composite carbon material

[0039] 40 mL of the prepared eutectic solvent is taken into a sealed glass bottle, and 6 mL of deionized water (15% by mass) is added, and the DES-deionized water mixed solvent is obtained by ultrasonic mixing.

[0040] 1.3516 g of ferric chloride hexahydrate and 3.564 g of nickel dichloride hexahydrate are weighed and added to the mixed solvent, and after ultrasonic mixing for a period of time until fully dissolved, 2 g of activated carbon powder and 0.984 g of polyvinylpyrrolidone dispersant (20% of the mass of the metal salt) are added to the solution, and ultrasonic mixing is performed for 30 min, and then 2.463 g of 2-methylimidazole is added to the above solution, and ultrasonic mixing is performed for 15 min, to form a uniform mixed solution.

[0041] The mixed solution is transferred to a water bath, and stirred at a speed of 200 rpm for 12 h at 60 ℃. After the reaction is completed, the glass bottle is taken out of the water bath, 10 mL of anhydrous ethanol is added and mixed with the reaction product, and then centrifuged to remove the supernatant, and the precipitate is collected and washed with deionized water and anhydrous ethanol for 3 times, and then placed in a blast drying oven at 60 ℃ for 24 h. After natural cooling to room temperature, the product is taken out and ground to obtain the iron-nickel bimetallic organic framework activated carbon composite material, denoted as DES-MOF.

[0042] (3) Preparation of electrode slurry

[0043] The iron-nickel bimetallic organic framework activated carbon composite material is used as an electrode active material, acetylene black is used as a conductive agent, and polyvinylidene fluoride is dissolved in N-methyl pyrrolidone solution at a mass ratio of 2.5% as a binder. The three are placed in a sample bottle at a mass ratio of 8:1:1, mixed uniformly by hand grinding for 10 min, and magnetically stirred for 12 h to obtain a uniform electrode slurry.

[0044] The electrode slurry is uniformly coated on a 11 cm×11 cm titanium plate (effective coating area is 7 cm×7 cm) using a four-side coating preparation device, and the electrode thickness is 150 μm. After drying at 60 ℃ for 12 h, the iron-nickel bimetallic organic framework activated carbon composite electrode material is obtained.

[0045] Example 2

[0046] A method for preparing an iron-nickel bimetallic organic framework activated carbon composite electrode material, comprising the following steps:

[0047] (1) Preparation of eutectic solvent

[0048] The eutectic solvent is prepared by mixing choline chloride and urea at a molar ratio of 1:1.5, heating and stirring in a 80 ℃ water bath, and then cooling the mixture to room temperature. Since the eutectic solvent has a low melting point, it remains in a liquid state even at room temperature.

[0049] (2) Preparation of iron-nickel bimetallic composite carbon material

[0050] 40 mL of the prepared eutectic solvent is added to a sealed glass bottle, and 8 mL of deionized water (15% by mass) is added. The mixture is ultrasonically mixed to obtain a DES-deionized water mixed solvent.

[0051] Take 1.3516 g of iron trichloride hexahydrate and 3.564 g of nickel dichloride hexahydrate and add them to the mixed solvent. After ultrasonic treatment for a period of time until fully dissolved, add 1.5 g of activated carbon powder and 0.984 g of polyvinylpyrrolidone dispersant (15% of the mass of the metal salt) to the mixture, and ultrasonic treat for 30 min. Then add 2.463 g of 2-methylimidazole to the above solution and ultrasonic treat for 15 min to form a homogeneous mixed solution.

[0052] Transfer the mixed solution to a water bath and react at 70°C for 11 h under a stirring rate of 200 rpm. After the reaction is completed, remove the glass bottle from the water bath, add 10 mL of anhydrous ethanol to the reaction mixture, centrifuge to remove the supernatant, collect the precipitate, and wash with deionized water and anhydrous ethanol for 3 times each, then place in a blast drying oven at 60°C for 24 h, cool to room temperature naturally, and then remove and grind to obtain the iron-nickel bimetallic organic framework activated carbon composite material.

[0053] (3) Preparation of electrode slurry

[0054] Use the iron-nickel bimetallic organic framework activated carbon composite material as the electrode active material, acetylene black as the conductive agent, and polyvinylidene fluoride dissolved in N-methylpyrrolidone solution at a mass ratio of 2.5% as the binder. Place the three in a sample bottle at a mass ratio of 8:1:1, mix them uniformly by hand grinding for 10 min, and magnetically stir for 12 h to obtain a uniform electrode slurry.

[0055] Use a four-sided coating preparation device to uniformly coat the electrode slurry on a 11 cm x 11 cm titanium plate (effective coating area is 7 cm x 7 cm), and the electrode thickness is 150 μm. Dry at 60°C for 12 h to obtain the iron-nickel bimetallic organic framework activated carbon composite electrode material.

[0056] Example 3

[0057] A method for preparing an iron-nickel bimetallic organic framework activated carbon composite electrode material, comprising the following steps:

[0058] (1) Preparation of eutectic solvent

[0059] Select choline chloride as the hydrogen bond acceptor and urea as the hydrogen bond donor to configure the eutectic solvent. Mix choline chloride and urea at a molar ratio of 1:2.5, heat and stir in a 80°C water bath, and then cool the eutectic solvent mixture to room temperature. Due to the low melting point property of the eutectic solvent, the eutectic solvent remains in liquid state even at room temperature.

[0060] (2) Preparation of iron-nickel bimetallic composite carbon material

[0061] 40 mL of the prepared eutectic solvent was added to a sealed glass bottle, and then 10 mL of deionized water (15% mass fraction) was added and ultrasonically mixed to obtain a DES-deionized water mixed solvent.

[0062] Weigh 1.3516 g of ferric chloride hexahydrate and 3.564 g of nickel dichloride hexahydrate and add them to the mixed solvent. After ultrasonic treatment for a period of time until they are fully dissolved, add 2.5 g of the previously treated activated carbon powder and 0.984 g of polyvinyl pyrrolidone dispersant (25% of the mass of the metal salt) and ultrasonicate for 30 min. Then, add 2.463 g of 2-methylimidazole to the above solution and ultrasonicate for 15 min to form a uniform mixed solution.

[0063] The mixed solution was transferred to a water bath and reacted at 80°C for 10 h at a stirring rate of 200 rpm. After the reaction was completed, the glass bottle was removed from the water bath and 10 mL of anhydrous ethanol was added to the reactants. The supernatant was decanted and the precipitate was collected and washed with deionized water and anhydrous ethanol three times each. After centrifugation, the precipitate was dried in a forced air drying oven at 60°C for 24 h. After cooling to room temperature, the precipitate was removed and ground to obtain an Fe-Ni bimetallic organic framework activated carbon composite.

[0064] (3) Preparation of electrode slurry

[0065] The iron-nickel bimetallic organic framework activated carbon composite material was used as the electrode active material, acetylene black was used as the conductive agent, and polyvinylidene fluoride was dissolved in N-methylpyrrolidone solution at a mass ratio of 2.5% as the binder. The three were placed in a sample bottle at a mass ratio of 8:1:1, ground with a handheld grinder for 10 minutes to mix them evenly, and magnetically stirred for 12 hours to obtain a uniform electrode slurry.

[0066] The electrode slurry was evenly coated on an 11cm×11cm titanium plate (the effective coating area was 7cm×7cm) using a four-sided coating preparation apparatus. The electrode bottom thickness was 150 μm. The iron-nickel bimetallic organic framework activated carbon composite electrode material was obtained by drying at 60°C for 12 h.

[0067] Comparative Example 1

[0068] The activated carbon electrode can be obtained by replacing the electrode active material in Example 1 with activated carbon and following the same other methods.

[0069] The schematic diagram of the CDI module structure is as follows Figure 1As shown in the figure, 1 is a glass plate, 2 is a silica gel gasket, 3 is a current collector, 4 is an ion exchange membrane, 5 is a hollow silica gel gasket, 6 is a plastic gasket, and 7 is an electrode coating. The asymmetric electrode is assembled by selecting a hybrid capacitive deionization module, the anode is a metal organic framework activated carbon composite electrode, and the cathode is an activated carbon electrode. A cation exchange membrane and an anion exchange membrane are arranged in front of the anode and cathode plates. The CDI module is mainly composed of a glass plate 1, a silica gel gasket 2, a current collector 3 coated with an electrode coating 7, a cation and anion exchange membrane 4, a hollow silica gel gasket 5, and a plastic gasket 6. The glass plate 1 serves as the end plate of the electrode and is fixed by screws. The glass plate 1 is provided with a water inlet and a water outlet to ensure the circulation of water in the electrode module. The water inlet is at the bottom, and after the treated liquid enters the CDI module, it passes through the water channel left by the plastic gasket 6 from bottom to top, and finally is discharged from the upper outlet. The current collector 3 is made of titanium plate, which serves as a substrate for the electrode material 7 and also transmits current. The silica gel gasket 2 and the hollow silica gel gasket 5 are respectively arranged between the glass plate 1 and the current collector 3, and between the cation and anion exchange membrane 4 and the plastic gasket 6, to ensure good sealing of the electrode module. The plastic gasket 6 provides a water flow channel and prevents short circuiting of the two electrodes. The cation and anion exchange membranes 4 only allow cations and anions to pass through, mainly to prevent the occurrence of common ion effect.

[0070] The capacitive deionization system uses a circulating flow mode, and the entire device is composed of a direct current power supply, a CDI module, a treated solution, and a peristaltic pump. The direct current power supply applies a direct current voltage of 1.5 V to the two electrodes through the tab of the current collector. The peristaltic pump pumps the solution into the electrode module at a flow rate of 10 mL / min. After the solution flows through the two electrode coating areas, it flows out of the electrode module through the water outlet and is pumped back into the original beaker by another peristaltic pump.

[0071] Results analysis

[0072] Figure 2 The SEM image of the DES-MOF powder prepared in Example 1 shows that a porous structure is formed on the surface of the DES-MOF material. This structure is beneficial to increasing the specific surface area of the material, thereby improving the ion adsorption capacity.

[0073] Figure 3 The salt concentration reduction comparison chart shows that in the same time period (150 s), the salt concentration reduction value of the DES-MOF prepared in Example 1 is about 72.66 mg / L, and the salt concentration reduction value of the activated carbon in Comparative Example 1 is about 22.01 mg / L, which is increased by 230%. This indicates that the DES-MOF has a faster removal efficiency. This is mainly because the MOF material is loaded on the activated carbon, which modifies the activated carbon and forms a porous structure, which is more conducive to adsorption.

[0074] The desalination performance of the capacitive deionization technology is generally evaluated by using the salt removal capacity (SAC) as an evaluation index, and the size of the salt removal capacity generally depends on the electrode coating properties, operating voltage, salt solution type and concentration and other experimental conditions, and the specific calculation formula is:

[0075]

[0076] wherein C 0 is the initial concentration of the sodium chloride solution, C t is the concentration of the sodium chloride solution after t minutes of desalination experiment, in mg / L, V S is the volume of the sodium chloride solution, in mL, and in the present application V S is 60 mL, m is the total mass of the coating of the two electrode sheets, in g.

[0077] Figure 4 is a desalination capacity comparison chart, and as shown in the chart, under the same reaction conditions, the desalination capacity of the activated carbon is 14.18±0.31 mg / g, the desalination capacity of the DES-MOF prepared in Example 1 is 23.74±1.37 mg / g, and the desalination capacity of the DES-MOF is increased by nearly 95.537% compared with the activated carbon electrode.

[0078] Figure 5 is a capacitive desalination effect chart of the electrode prepared in Example 1 after cycle test, and as shown in the chart, under the condition that the salt solution concentration is 2.5 g / L, after 10 times of capacitive desalination cycle test on 60 mL of salt solution at a voltage of 1.5 V, it can be seen that the desalination capacity can still be maintained at 100 mg / L.

[0079] In summary, in the preparation process of the iron-nickel bimetallic organic framework activated carbon composite material, the eutectic solvent and water mixed solvent are used as the ligand solution, and in the synthesis process, the eutectic solvent not only acts as a solvent, but also acts as a structure directing agent. The components in the eutectic solvent, such as chloride ions and choline ions, can coordinate with metal ions, act as templates or ligands to guide the formation of pores, control the pore structure of MOFs, enhance the adsorption and separation performance, and the chloride ions in the eutectic solvent or the ammonia generated by decomposition can act as a structure directing agent to affect the coordination mode of the metal nodes, thereby controlling the pore size and porosity, and realizing efficient removal of salt ions in water.

[0080] It is to be understood that every range of values disclosed herein is to be understood to encompass any and every sub-range of values within the range. Although the preferred embodiments of the invention have been described above, it will be appreciated that those skilled in the art, on consideration of this disclosure, will be able to devise additional embodiments that, although not explicitly described or shown herein, nonetheless fall within the scope of the present invention. Accordingly, the appended claims are intended to include within their scope all such alternatives, modifications and variations as fall within the scope of the present invention. Various features and aspects of the present invention will become apparent from the following examples, which are intended only to exemplify the invention. It should be understood, of course, that in the various examples of the present invention, the specific phrasing of the claims will depend on the exact nature of the claims sought.

[0081] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the present application can be practiced otherwise than as specifically described herein.

Claims

1. A method for preparing a bimetallic organic framework electrode material based on a eutectic solvent, characterized in that: The following steps are involved: mixing the eutectic solvent with water to obtain a mixed solvent; A mixed solvent containing a eutectic solvent and water is used as a ligand solution, a soluble iron salt and a soluble nickel salt are added to the mixed solvent, activated carbon powder and a dispersant are added after ultrasonic dissolution, ultrasonic mixing is performed, and then 2-methylimidazole ligand is added to obtain an iron-nickel bimetallic organic framework activated carbon composite material precursor solution; subjecting the iron-nickel bimetallic organic framework activated carbon composite material precursor solution to a water bath reaction, and post-treating the water bath reaction product to obtain an iron-nickel bimetallic organic framework activated carbon composite material; The iron-nickel bimetallic organic framework activated carbon composite material is used as an electrode active material, mixed with a conductive agent and a binder to obtain an electrode slurry, and the electrode slurry is coated on an electrode plate and dried to obtain an iron-nickel bimetallic organic framework activated carbon composite electrode material.

2. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: The eutectic solvent consists of a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, the hydrogen bond donor is urea, and the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1.5-2.

5.

3. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: In the mixed solvent, the volume ratio of eutectic solvent to water is 20:3~5.

4. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: The ratio of the iron element in the soluble iron salt, the nickel element in the soluble nickel salt, and the mixed solvent is 1 mol: 3 mol: 46 mL~50 mL.

5. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: The dosage ratio of activated carbon powder to mixed solvent is 1.5 g~2.5 g:46 mL~50 mL, and the mass fraction of the dispersant in the soluble iron salt and the soluble nickel salt is 15%~25%.

6. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: The water bath reaction temperature is 60℃~80℃, and the reaction time is 10 h~12 h.

7. The method for preparing a bimetallic organic framework electrode material based on a eutectic solvent according to claim 1, characterized in that: The mass ratio of the iron-nickel bimetallic organic framework activated carbon composite material to the conductive agent and the binder is 80~90:5~10:5~10.

8. A bimetallic organic framework electrode material based on a eutectic solvent prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the bimetallic organic framework electrode material based on eutectic solvent according to claim 8 in a hybrid capacitive deionization device, characterized in that: The bimetallic organic framework composite electrode material based on eutectic solvent is applied to the hybrid capacitive deionization device to remove salt ions in water.

10. The use according to claim 9, characterized in that A hybrid capacitor deionization module is selected to assemble an asymmetric electrode, the anode is the bimetallic organic framework electrode material based on the eutectic solvent as described in claim 8, the cathode is an activated carbon electrode, and a cation exchange membrane and an anion exchange membrane are set in front of the anode and cathode plates.

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