Preparation method of metal organic framework compound-graphene electrode material

Abstract

The application relates to a preparation method of a metal organic framework compound-graphene electrode material, and belongs to the technical field of graphene batteries. The electrode material comprises a carbon base layer, a transition metal doped layer and a graphene enrichment layer three-layer structure, wherein the doped graphene powder is doped by nitrogen, cobalt and nickel, the specific capacitance is improved, and the structure presents a porous structure, the embedding strength of the graphene powder and a polypyrrole matrix is large, the graphene powder is not prone to migration enrichment with irradiation, the magnetic adsorption and microwave irradiation process is adopted, the magnetic graphene is enriched on the surface layer, the doped graphene powder and the polypyrrole matrix are protected, and the capacitance retention rate reaches 96.84-98.01% after 1000 cycles under a current density of 0.5 A / g through testing, the stability is obviously better than that of an existing carbon-based electrode material, and the specific capacitance reaches 685.7-703.1 F.g ‑1 .

Description

Technical Field

[0001] This invention belongs to the field of graphene battery technology, specifically, it relates to a method for preparing a metal-organic framework compound-graphene electrode material. Background Technology

[0002] Supercapacitors are a new type of energy storage device with performance between that of secondary batteries and traditional capacitors. They have higher power density than batteries, higher specific capacitance and energy density than traditional capacitors, longer cycle life, higher reversibility, and no environmental pollution. In particular, they have a short charging time and can be used in energy storage devices, power supply systems, and many electronic devices.

[0003] Based on different energy storage mechanisms, supercapacitors are mainly divided into two categories: one is the electric double-layer capacitor, which uses carbon materials as electrode materials, and the other is the Faraday capacitor, also known as a pseudocapacitor or quasi-capacitor, which uses redox reactions to store electrical energy in an electrochemical manner. Among them, the electric double-layer capacitor has advantages such as high power and long cycle life, but its energy density and specific capacitance are relatively small. In contrast, the specific capacitance of the pseudocapacitor is 10-100 times that of the electric double-layer capacitor, but its cycle stability is poor.

[0004] Graphene is a single-layer two-dimensional honeycomb crystal composed of sp2 hybrid carbon atoms tightly packed together. It has a large theoretical specific surface area, good electrical conductivity and chemical stability, and is considered an ideal electrode material for electric double-layer capacitors. However, as a carbon-based material, it has relatively low energy density and specific capacitance.

[0005] In existing technologies, graphene is doped into the electrodes of pseudocapacitors to improve their stability. For example, Chinese patent CN109087724B mixes graphene with other raw materials, coats it onto the electrode, and cures it to form a graphene-doped electrode material. This can improve the charge and discharge stability of the electrode to a certain extent. However, the amount of graphene doping is limited, and the improvement is not obvious. When the amount of graphene doping is too high, the graphene sheets form discontinuous isolation, which can lead to the deterioration of the capacitor's performance. Summary of the Invention

[0006] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a method for preparing metal-organic framework compound-graphene electrode materials.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing a metal-organic framework compound-graphene electrode material includes the following steps:

[0009] Step S1: Graphene oxide, 2,3-diaminopyridine and deionized water are ultrasonically dispersed under nitrogen protection to completely dissolve 2,3-diaminopyridine and uniformly disperse graphene oxide. Then, the mixture is heated to 100°C and stirred under reflux for 3-5 hours. The gel is filtered out, freeze-dried, and dry-milled to obtain mesoporous graphene powder.

[0010] Furthermore, the ratio of graphene oxide, 2,3-diaminopyridine, and deionized water is 10g:0.16-0.2g:80-100mL. The reaction between 2,3-diaminopyridine and the oxygen-containing groups on the surface of graphene oxide causes the graphene to exhibit a wrinkled shape and a certain degree of cross-linking, resulting in a wrinkled porous structure. At the same time, nitrogen doping is introduced into the graphene oxide.

[0011] Step S2: Dissolve cobalt nitrate and nickel nitrate in deionized water to prepare an impregnation solution. Add mesoporous graphene powder to the impregnation solution and disperse it by ultrasonication. Then, slowly add ethylenediamine in ethanol solution until the pH of the reaction system is 8.5-9.0. Stir the reaction for 5-8 hours, centrifuge to remove the lower precipitate, place the precipitate in a drying oven, dry it at no more than 80°C to constant weight, and then break it up to obtain doped graphene powder.

[0012] Furthermore, the concentration of cobalt in the impregnation solution is 0.1-0.2 mol / L, the concentration of nickel is 0.05-0.08 mol / L, and the solid-liquid ratio of the impregnation solution for the mesoporous graphene powder is 1:5.

[0013] Step S3: Mix pyrrole monomer, doped graphene powder, magnetic graphene and ethanol solution at high speed, then add iodine powder, set the stirring speed to 400-600 rpm, heat to 82-88℃ and reflux for 65-80 min, then rotary evaporate until the viscosity reaches 3200 cP to prepare metal composite organic adhesive.

[0014] Furthermore, the ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder and ethanol solution is 1 mol: 5.8-6.5 g: 1.2-1.6 g: 0.1 g: 300-350 mL, and the concentration of ethanol solution is 30%.

[0015] Step S4: The metal-organic composite adhesive is coated onto the surface of a glassy carbon sheet to form a composite substrate. The composite substrate is then magnetically adsorbed and subjected to microwave irradiation for 3-4 hours. Microwave irradiation promotes the movement of graphene groups in the metal-organic composite adhesive, resulting in uniform dispersion of the graphene-based material. Among them, the porous doped graphene has a high intercalation strength with the polypyrrole matrix, and its movement and migration are small under the same irradiation intensity. The sheet-like magnetic graphene is enriched on the surface of the composite substrate under magnetic guidance, forming a carbon base layer, a transition metal doped layer, and a graphene enrichment layer structure, thus producing a metal-organic framework compound / graphene electrode material.

[0016] Furthermore, the coating thickness of the metal-composite organic adhesive is 0.8-1.0 mm, the magnetic field strength for magnetic adsorption is 2200-2600 Gs, and the microwave irradiation frequency is 3.5-5 GHz.

[0017] The magnetic graphene is prepared by the following method:

[0018] Step A1: Disperse graphene oxide in ferric chloride solution using ultrasound, heat to 80-100℃, set the stirring speed to 600-800 rpm, add ammonia water and stir for 20-30 min while keeping warm, let stand and cool to room temperature, filter out the gel, dry to constant weight and then dry grind to obtain iron composite powder.

[0019] Furthermore, the amounts of graphene oxide, ferric chloride solution, and ammonia are 5g: 120-150mL: 10-15mL, the concentration of ferric chloride solution is 0.1mol / L, and the concentration of ammonia is 25%.

[0020] Step A2: Prepare a hydrazine hydrate solution, add iron composite powder and ultrasonically disperse at room temperature, filter, dry the filter cake to constant weight, and break it up to obtain magnetic graphene.

[0021] Furthermore, the ratio of iron composite powder to hydrazine hydrate solution is 5g:40mL, the concentration of hydrazine hydrate solution is 30%, the ultrasonic dispersion frequency is 33kHz, and the ultrasonic dispersion time is 35-40min.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention provides a magnetic adsorption and microwave irradiation method to prepare a three-layer metal-organic framework compound-graphene electrode material with a carbon substrate layer, a transition metal doped layer, and a graphene enriched layer. By fully utilizing the stability of graphene, the capacitance retention rate reaches 96.84-98.01% after 1000 cycles at a current density of 0.5 A / g, which is significantly better than the stability of existing carbon-based electrode materials.

[0024] 2. This invention discloses a nitrogen, cobalt, and nickel-doped graphene powder. Utilizing the reaction between 2,3-diaminopyridine and the oxygen-containing groups on the surface of graphene oxide, the graphene exhibits a wrinkled structure. The resulting cross-linked gel is porous, facilitating the loading of cobalt and nickel via impregnation to improve the capacitance performance of the carbon material. The porous doped graphene powder exhibits strong intercalation with the polypyrrole matrix, making it less prone to migration and enrichment during irradiation. This allows for the use of magnetic adsorption and microwave irradiation processes. Furthermore, through in-situ polymerization and polypyrrole composite, the electrode material possesses a high specific capacitance. Testing shows a specific capacitance of 685.7-703.1 F·g at a current density of 0.5 A / g. -1 . Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment prepares a metal-organic framework compound-graphene electrode material, and the specific implementation process is as follows:

[0028] 1) Preparation of doped graphene powder

[0029] a1. High-purity nitrogen gas was introduced into the reactor to create a nitrogen protective atmosphere. Graphene oxide, 2,3-diaminopyridine, and deionized water were added to the reactor and ultrasonically dispersed at 40 kHz for 30 min to completely dissolve the 2,3-diaminopyridine and uniformly disperse the graphene oxide. Then, the stirring speed was set to 240 rpm, the temperature was raised to 100℃, and the mixture was stirred and refluxed for 3 h. The gel was filtered out, freeze-dried to constant weight, and dry-milled to a fineness of not less than 1000 mesh to obtain mesoporous graphene powder. The ratio of graphene oxide, 2,3-diaminopyridine, and deionized water was 10 g: 0.2 g: 80 mL. In the experiment, 10 g of graphene oxide was used as the quantification, which was provided by Shanghai Maoguo Nanotechnology Co., Ltd. The same raw materials were used in the following examples.

[0030] a2. Cobalt nitrate and nickel nitrate were dissolved in deionized water, and the concentration of cobalt was controlled at 0.1 mol / L and the concentration of nickel was 0.08 mol / L to prepare an impregnation solution. The mesoporous graphene powder prepared above was added to the impregnation solution at a solid-liquid ratio of 1:5. The solution was ultrasonically dispersed at 28 kHz for 10 min. Then, ethylenediamine ethanol solution was added dropwise at 10 drops / min until the pH of the reaction system was 9.0. The reaction was stirred for 5 h. The lower precipitate was collected by centrifugation and placed in a drying oven. The precipitate was dried at 80 ℃ to constant weight and then dispersed using a blade-type disperser to obtain doped graphene powder.

[0031] 2) Preparation of magnetic graphene

[0032] b1. Prepare a 0.1 mol / L ferric chloride solution. Disperse graphene oxide in the ferric chloride solution using ultrasonication at 40 kHz. Heat the solution to 100°C and set the stirring speed to 800 rpm. Add 25% industrial ammonia solution and stir for 20 min. Then allow the solution to cool to room temperature. Filter out the gel and dry it in a 120°C drying oven until constant weight. Then dry grind the gel to a fineness of 800 mesh to obtain iron composite powder. The ratio of graphene oxide, ferric chloride solution, and ammonia solution is 5 g: 150 mL: 15 mL.

[0033] b2. Prepare a 30% hydrazine hydrate solution, add iron composite powder at a ratio of 5g:40mL, and disperse it by ultrasonication at 33kHz for 35min. Then filter the powder, dry it at 60℃ to constant weight, and break it up to obtain magnetic graphene.

[0034] 3) Preparation of metal-organic framework compound-graphene electrode materials

[0035] s1. Pyrrole monomer, doped graphene powder, magnetic graphene, and ethanol solution are added to a reaction vessel and mixed at 1200 rpm for 5 min. Then, iodine powder is added, the stirring speed is set to 600 rpm, the temperature is raised to 88℃ and refluxed for 65 min, and then rotary evaporated until the viscosity reaches 3200 cP to prepare a metal composite organic adhesive. The ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder, and ethanol solution is 1 mol: 5.8 g: 1.5 g: 0.1 g: 300 mL, and the concentration of ethanol solution is 30%.

[0036] s2. Apply the metal-organic composite adhesive to the surface of the glass carbon sheet, controlling the coating thickness to 0.8 mm to form a composite substrate. Then, fix the composite substrate under a flat electromagnet and magnetically attract it from the side closest to the metal-organic composite adhesive, controlling the magnetic field strength to 2200 Gs. Simultaneously, apply microwave irradiation at a frequency of 3.5 GHz to the composite substrate and control the treatment time to 3 hours to form a metal-organic framework compound / graphene electrode material.

[0037] Example 2

[0038] This embodiment prepares a metal-organic framework compound-graphene electrode material, and the specific implementation process is as follows:

[0039] 1) Preparation of doped graphene powder

[0040] a1. High-purity nitrogen gas was introduced into the reactor to create a nitrogen protective atmosphere. Graphene oxide, 2,3-diaminopyridine, and deionized water were added to the reactor and ultrasonically dispersed at 40 kHz for 30 min to completely dissolve the 2,3-diaminopyridine and uniformly disperse the graphene oxide. Then, the stirring speed was set to 240 rpm, the temperature was raised to 100℃, and the mixture was stirred and refluxed for 5 h. The gel was filtered out, freeze-dried to constant weight, and dry-milled to a fineness of not less than 1000 mesh to obtain mesoporous graphene powder. The ratio of graphene oxide, 2,3-diaminopyridine, and deionized water was 10 g: 0.16 g: 90 mL. In the experiment, 10 g of graphene oxide was used as the quantification. Graphene oxide was provided by Shanghai Maoguo Nanotechnology Co., Ltd. The same raw materials were used in the following examples.

[0041] a2. Cobalt nitrate and nickel nitrate were dissolved in deionized water, and the concentration of cobalt was controlled at 0.2 mol / L and the concentration of nickel was 0.05 mol / L to prepare an impregnation solution. The mesoporous graphene powder prepared above was added to the impregnation solution at a solid-liquid ratio of 1:5. The solution was ultrasonically dispersed at 28 kHz for 10 min. Then, ethylenediamine ethanol solution was added dropwise at 10 drops / min until the pH of the reaction system reached 8.5. The reaction was stirred for 8 h. The lower precipitate was collected by centrifugation and placed in a drying oven. The precipitate was dried at 80 ℃ to constant weight and then dispersed using a blade-type disperser to obtain doped graphene powder.

[0042] 2) Preparation of magnetic graphene

[0043] b1. Prepare a 0.1 mol / L ferric chloride solution. Disperse graphene oxide in the ferric chloride solution using ultrasonication at 40 kHz. Heat the solution to 80 ℃, set the stirring speed to 600 rpm, add 25% industrial ammonia water, and stir for 30 min. Then let it stand and cool to room temperature, filter out the gel, and dry it in a 120 ℃ drying oven to constant weight. Then dry grind it to a fineness of 800 mesh to obtain iron composite powder. The ratio of graphene oxide, ferric chloride solution and ammonia water is 5 g: 120 mL: 10 mL.

[0044] b2. Prepare a 30% hydrazine hydrate solution, add iron composite powder at a ratio of 5g:40mL, and disperse it by ultrasonication at 33kHz for 40min. Then filter the powder, dry it at 60℃ to constant weight, and break it up to obtain magnetic graphene.

[0045] 3) Preparation of metal-organic framework compound-graphene electrode materials

[0046] s1. Pyrrole monomer, doped graphene powder, magnetic graphene, and ethanol solution are added to a reaction vessel and mixed at 1200 rpm for 5 min. Then, iodine powder is added, the stirring speed is set to 400 rpm, the temperature is raised to 82℃ and refluxed for 80 min, and then rotary evaporated until the viscosity reaches 3200 cP to prepare a metal composite organic adhesive. The ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder, and ethanol solution is 1 mol: 6.5 g: 1.2 g: 0.1 g: 350 mL, and the concentration of ethanol solution is 30%.

[0047] s2. Apply the metal-organic composite adhesive to the surface of the glass carbon sheet, controlling the coating thickness to 0.9 mm to form a composite substrate. Then, fix the composite substrate under a flat electromagnet and magnetically attract it from the side closest to the metal-organic composite adhesive, controlling the magnetic field strength to 2400 Gs. Simultaneously, apply microwave irradiation at a frequency of 4.0 GHz to the composite substrate and control the processing time to 3.5 h to form a metal-organic framework compound / graphene electrode material.

[0048] Example 3

[0049] This embodiment prepares a metal-organic framework compound-graphene electrode material, and the specific implementation process is as follows:

[0050] 1) Preparation of doped graphene powder

[0051] a1. High-purity nitrogen gas was introduced into the reactor to create a nitrogen protective atmosphere. Graphene oxide, 2,3-diaminopyridine, and deionized water were added to the reactor and ultrasonically dispersed at 40 kHz for 30 min to completely dissolve the 2,3-diaminopyridine and uniformly disperse the graphene oxide. Then, the stirring speed was set to 240 rpm, the temperature was raised to 100℃, and the mixture was stirred and refluxed for 4.5 h. The gel was filtered out, freeze-dried to constant weight, and dry-milled to a fineness of not less than 1000 mesh to obtain mesoporous graphene powder. The ratio of graphene oxide, 2,3-diaminopyridine, and deionized water was 10 g: 0.18 g: 100 mL. In the experiment, 10 g of graphene oxide was used as the quantification. Graphene oxide was provided by Shanghai Maoguo Nanotechnology Co., Ltd. The same raw materials were used in the following examples.

[0052] a2. Cobalt nitrate and nickel nitrate were dissolved in deionized water, and the concentration of cobalt was controlled at 0.15 mol / L and the concentration of nickel was 0.06 mol / L to prepare an impregnation solution. The mesoporous graphene powder prepared above was added to the impregnation solution at a solid-liquid ratio of 1:5. The solution was ultrasonically dispersed at 28 kHz for 10 min. Then, ethylenediamine ethanol solution was added dropwise at 10 drops / min until the pH of the reaction system reached 9.0. The reaction was stirred for 7 h. The lower precipitate was collected by centrifugation and placed in a drying oven. The precipitate was dried at 80 ℃ to constant weight and then dispersed using a blade-type disperser to obtain doped graphene powder.

[0053] 2) Preparation of magnetic graphene

[0054] b1. Prepare a 0.1 mol / L ferric chloride solution. Disperse graphene oxide in the ferric chloride solution using ultrasonication at 40 kHz. Heat the solution to 95°C and set the stirring speed to 800 rpm. Add 25% industrial ammonia solution and stir for 22 min. Then allow the solution to cool to room temperature. Filter out the gel and dry it in a 120°C drying oven until constant weight. Then dry grind the gel to a fineness of 800 mesh to obtain iron composite powder. The ratio of graphene oxide, ferric chloride solution, and ammonia solution is 5 g: 140 mL: 13 mL.

[0055] b2. Prepare a 30% hydrazine hydrate solution, add iron composite powder at a ratio of 5g:40mL, and disperse it by ultrasonication at 33kHz for 35-40min. Then filter the powder, dry it at 60℃ to constant weight, and break it up to obtain magnetic graphene.

[0056] 3) Preparation of metal-organic framework compound-graphene electrode materials

[0057] s1. Pyrrole monomer, doped graphene powder, magnetic graphene, and ethanol solution are added to a reaction vessel and mixed at 1200 rpm for 5 min. Then, iodine powder is added, the stirring speed is set to 600 rpm, the temperature is raised to 85℃ and refluxed for 75 min. After that, the mixture is rotary evaporated until the viscosity reaches 3200 cP to prepare a metal composite organic adhesive. The ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder, and ethanol solution is 1 mol: 6.1 g: 1.3 g: 0.1 g: 330 mL, and the concentration of ethanol solution is 30%.

[0058] s2. Apply the metal-organic composite adhesive to the surface of the glass carbon sheet, controlling the coating thickness to 0.8 mm to form a composite substrate. Then, fix the composite substrate under a flat electromagnet and magnetically attract it from the side closest to the metal-organic composite adhesive, controlling the magnetic field strength to 2500 Gs. Simultaneously, apply microwave irradiation at a frequency of 4.0 GHz to the composite substrate and control the treatment time to 4 hours to form a metal-organic framework compound / graphene electrode material.

[0059] Example 4

[0060] This embodiment prepares a metal-organic framework compound-graphene electrode material, and the specific implementation process is as follows:

[0061] 1) Preparation of doped graphene powder

[0062] a1. High-purity nitrogen gas was introduced into the reactor to create a nitrogen protective atmosphere. Graphene oxide, 2,3-diaminopyridine, and deionized water were added to the reactor and ultrasonically dispersed at 40 kHz for 30 min to completely dissolve the 2,3-diaminopyridine and uniformly disperse the graphene oxide. Then, the stirring speed was set to 240 rpm, the temperature was raised to 100℃, and the mixture was stirred and refluxed for 4 h. The gel was filtered out, freeze-dried to constant weight, and dry-milled to a fineness of not less than 1000 mesh to obtain mesoporous graphene powder. The ratio of graphene oxide, 2,3-diaminopyridine, and deionized water was 10 g: 0.18 g: 90 mL. In the experiment, 10 g of graphene oxide was used as the quantification. Graphene oxide was provided by Shanghai Maoguo Nanotechnology Co., Ltd. The same raw materials were used in the following examples.

[0063] a2. Cobalt nitrate and nickel nitrate were dissolved in deionized water, and the concentration of cobalt was controlled at 0.18 mol / L and the concentration of nickel was 0.06 mol / L to prepare an impregnation solution. The mesoporous graphene powder prepared above was added to the impregnation solution at a solid-liquid ratio of 1:5. The solution was ultrasonically dispersed at 28 kHz for 10 min. Then, ethylenediamine ethanol solution was added dropwise at 10 drops / min until the pH of the reaction system reached 9.0. The reaction was stirred for 7 h. The lower precipitate was collected by centrifugation and placed in a drying oven. The precipitate was dried at 80 ℃ to constant weight and then dispersed using a blade-type disperser to obtain doped graphene powder.

[0064] 2) Preparation of magnetic graphene

[0065] b1. Prepare a 0.1 mol / L ferric chloride solution. Disperse graphene oxide in the ferric chloride solution using ultrasonication at 40 kHz. Heat the solution to 90°C and set the stirring speed to 700 rpm. Add 25% industrial ammonia solution and stir for 28 min. Then allow the solution to cool to room temperature. Filter out the gel and dry it in a 120°C drying oven until constant weight. Then dry grind the gel to a fineness of 800 mesh to obtain iron composite powder. The ratio of graphene oxide, ferric chloride solution, and ammonia solution is 5 g: 130 mL: 10 mL.

[0066] b2. Prepare a 30% hydrazine hydrate solution, add iron composite powder at a ratio of 5g:40mL, and disperse it by ultrasonication at 33kHz for 38min. Then filter the powder, dry it at 60℃ to constant weight, and break it up to obtain magnetic graphene.

[0067] 3) Preparation of metal-organic framework compound-graphene electrode materials

[0068] s1. Pyrrole monomer, doped graphene powder, magnetic graphene, and ethanol solution are added to a reaction vessel and mixed at 1200 rpm for 5 min. Then, iodine powder is added, the stirring speed is set to 500 rpm, the temperature is raised to 85℃ and refluxed for 80 min, and then rotary evaporated until the viscosity reaches 3200 cP to prepare a metal composite organic adhesive. The ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder, and ethanol solution is 1 mol: 6.3 g: 1.6 g: 0.1 g: 350 mL, and the concentration of ethanol solution is 30%.

[0069] s2. Apply the metal-organic composite adhesive to the surface of the glass carbon sheet, controlling the coating thickness to 1.0 mm to form a composite substrate. Then, fix the composite substrate under a flat electromagnet and magnetically attract it from the side closest to the metal-organic composite adhesive, controlling the magnetic field strength to 2600 Gs. Simultaneously, apply microwave irradiation at a frequency of 5.0 GHz to the composite substrate and control the processing time to 3.5 h to form a metal-organic framework compound / graphene electrode material.

[0070] The electrode materials prepared in Examples 1-4 were subjected to constant current charge-discharge tests using a Blue Battery testing system. The current density was 0.5 A / g, and the charge-discharge cycle was 1000 times. The specific test data are shown in Table 1.

[0071] Table 1

[0072] Example 1 Example 2 Example 3 Example 4 <![CDATA[Specific capacitance / F·g -1 > 685.7 703.1 692.5 698.6 Capacitance retention rate / % 97.42 96.84 97.83 98.01

[0073] As shown in Table 1, the specific capacitance of the electrode material prepared in this invention is 685.7-703.1 F·g. -1 It has a high specific capacitance, and the capacitance retention rate reaches 96.84-98.01% after 1000 cycles, demonstrating high stability.

[0074] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a metal-organic framework compound-graphene electrode material, characterized in that, Includes the following steps: Step S1: Graphene oxide, 2,3-diaminopyridine and deionized water are ultrasonically dispersed under nitrogen protection, heated to 100℃ and stirred under reflux for 3-5 hours, the gel is filtered out, freeze-dried and dry-milled to obtain mesoporous graphene powder. Step S2: Dissolve cobalt nitrate and nickel nitrate in deionized water to prepare an impregnation solution. Disperse the mesoporous graphene powder and the impregnation solution by ultrasonication. Add ethylenediamine in ethanol solution until the pH of the reaction system is 8.5-9.

0. Stir the reaction for 5-8 hours. Centrifuge, take the lower precipitate, dry it to constant weight, and break it up to obtain doped graphene powder. Step S3: Mix pyrrole monomer, doped graphene powder, magnetic graphene and ethanol solution, then add iodine powder, stir at 400-600 rpm, heat to 82-88℃ and reflux for 65-80 min, then rotary evaporate until the viscosity reaches 3200 cP to prepare metal composite organic adhesive. Step S4: Apply the metal-organic composite adhesive to the surface of the glass carbon sheet to form a composite substrate. Magnetic adsorption is applied to the composite substrate, followed by microwave irradiation treatment for 3-4 hours to produce a metal-organic framework compound / graphene electrode material. The magnetic graphene is prepared by the following method: Step A1: Ultrasonically disperse graphene oxide in ferric chloride solution, heat to 80-100℃, add ammonia water and stir for 20-30 minutes, let stand and cool to room temperature, filter out the gel, dry to constant weight, and dry grind to obtain iron composite powder; Step A2: Prepare a hydrazine hydrate solution, add iron composite powder and ultrasonically disperse at room temperature, filter, dry the filter cake to constant weight, and break it up to obtain magnetic graphene.

2. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 1, characterized in that, In step S1, the ratio of graphene oxide, 2,3-diaminopyridine, and deionized water is 10g:0.16-0.2g:80-100mL.

3. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 2, characterized in that, The concentration of cobalt in the impregnation solution is 0.1-0.2 mol / L, the concentration of nickel is 0.05-0.08 mol / L, and the solid-liquid ratio of the impregnation solution for mesoporous graphene powder is 1:

5.

4. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 3, characterized in that, The ratio of pyrrole monomer, doped graphene powder, magnetic graphene, iodine powder and ethanol solution is 1 mol: 5.8-6.5 g: 1.2-1.6 g: 0.1 g: 300-350 mL, and the concentration of ethanol solution is 30%.

5. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 4, characterized in that, The coating thickness of the metal-composite organic adhesive is 0.8-1.0 mm, the magnetic field strength for magnetic adsorption is 2200-2600 Gs, and the microwave irradiation frequency is 3.5-5 GHz.

6. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 1, characterized in that, In step A1, the amounts of graphene oxide, ferric chloride solution, and ammonia are 5g: 120-150mL: 10-15mL, the concentration of ferric chloride solution is 0.1mol / L, and the concentration of ammonia is 25%.

7. The method for preparing a metal-organic framework compound-graphene electrode material according to claim 6, characterized in that, The ratio of iron composite powder to hydrazine hydrate solution was 5g:40mL, the concentration of hydrazine hydrate solution was 30%, the ultrasonic dispersion frequency was 33kHz, and the ultrasonic dispersion time was 35-40min.