Preparation method and application of amino-modified single-benzene-ring copper-based MOFs (Metal-Organic Frameworks)

Abstract

The invention discloses a preparation method and application of amino-modified single-benzene-ring copper-based MOFs (metal organic frameworks), and the method comprises the following steps: dropwise adding a copper nitrate monohydrate solution into a diamino terephthalic acid solution, fully stirring to react, and centrifugally washing and drying the product to obtain the amino-modified single-benzene-ring copper-based MOFs. The amino-modified single-benzene-ring copper-based MOFs are used for electrocatalytic reduction of carbon dioxide. The prepared amino-modified single-benzene-ring copper-based MOFs have unique morphology, active sites can be exposed on the inner surface and the outer surface, the accessibility of the active sites is improved, and meanwhile the reaction mass transfer capacity is enhanced.

Description

Technical Field

[0001] This invention relates to the field of CO2 reduction catalyst synthesis technology, specifically to a method for preparing amino-modified monobenzene ring copper-based MOFs and their applications. Background Technology

[0002] Electrocatalytic carbon dioxide reduction (CO2RR) often faces challenges such as low selectivity. Metal-organic frameworks (MOFs), especially copper (Cu) MOFs, have shown great potential in catalysis, gas adsorption and separation, and sensing due to their open pore structure, high specific surface area, and tunable chemical environment. However, Cu-based MOFs prepared by conventional methods (such as solvothermal methods) typically exhibit random three-dimensional bulk morphologies or large crystal sizes. Numerous active sites (such as Cu ion sites) are deeply embedded within the material, making it difficult for reactant molecules to contact them, resulting in low utilization efficiency of intrinsic active sites. Furthermore, the dense bulk structure leads to long diffusion paths for matter (ions / molecules) and electron transport distances, severely limiting their reaction kinetics and efficiency in electrocatalysis and other applications. These shortcomings mainly stem from the difficulty of precisely controlling the crystal nucleation and growth kinetics at the molecular level using existing synthetic techniques, which cannot effectively guide anisotropic crystal growth, thus limiting the formation of low-dimensional (e.g., two-dimensional) or hierarchical structures (e.g., three-dimensional nanoflowers). To overcome these limitations and successfully prepare Cu-based MOFs with ultrathin two-dimensional nanosheets or open hierarchical nanoflower structures, the technical barriers are as follows: (1) How to achieve separate control of nucleation rate and growth rate by optimizing synthesis parameters (such as coordination competition and interface energy regulation) to induce the directional assembly of two-dimensional layered structures; (2) How to stabilize the ultrathin nanosheet structure with high surface energy and prevent it from stacking or spontaneously transforming into a more thermodynamically stable three-dimensional bulk crystal during hydrothermal / solvothermal processes; (3) How to develop a mild, simple and highly reproducible preparation strategy to overcome the shortcomings of traditional high-temperature and high-pressure solvothermal methods in terms of controllability and large-scale production. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing amino-modified monobenzene ring copper-based MOFs and their applications, which can be used for electrocatalytic CO2 reduction to prepare alkanes and C2 products; the material preparation method is simple, low in cost, and has broad application prospects.

[0004] In one aspect of the present invention, a method for preparing amino-modified monophenyl ring copper-based MOFs is provided. According to an embodiment of the present invention, the method includes the following steps: adding a copper nitrate monohydrate solution dropwise to a diaminoterephthalic acid solution, stirring the reaction thoroughly, and centrifuging, washing, and drying the product to obtain the amino-modified monophenyl ring copper-based MOFs. The copper nitrate monohydrate solution is obtained by dissolving copper nitrate monohydrate in a solvent, and the concentration of the copper nitrate monohydrate solution is 0.02~0.4 mol / L; the diaminoterephthalic acid solution is obtained by dissolving diaminoterephthalic acid in a solvent, and the concentration of the diaminoterephthalic acid solution is 0.025~0.05 mol / L; the solvent is ethanol or deionized water; the stirring reaction is carried out at room temperature for 0.5~2 h.

[0005] Rigid monobenzene ring ligands bridging copper nodes can shorten the distance between adjacent copper active sites, providing an optimized geometry for the C-C coupling step and thus promoting the formation pathway of C2 products. Secondly, the precisely introduced amino (-NH2) groups on the ligands act as strong electron donors, effectively modulating the electronic state density and d-band center position of the copper active center. This can enhance the adsorption strength of key reaction intermediates (such as adsorbed CO) at the copper sites, thereby improving reaction kinetics.

[0006] In addition, the method for preparing amino-modified monobenzene ring copper-based MOFs according to the above embodiments of the present invention may also have the following additional technical features:

[0007] In some embodiments of the present invention, the copper nitrate monohydrate is dissolved in the solvent by ultrasonic dissolution for 10-30 min; the diaminoterephthalic acid is dissolved in the solvent by ultrasonic dissolution for 5-20 min; and the centrifugal washing is performed using ethanol or deionized water, and the number of centrifugal washing cycles is 2-3.

[0008] In some embodiments of the present invention, when the solvent is ethanol, the amino-modified monobenzene ring copper-based MOFs are micro-nano flowers of 0.2~2 µm. Hydrated copper nitrate provides the metallic copper nodes, and diaminoterephthalic acid serves as the organic linker. In solution, the two self-assemble through coordination bonding between copper ions and carboxyl oxygen atoms to form a metal-organic framework based on copper-oxygen bonds. In the ethanol solution, the weak coordination of ethanol molecules slows down the nucleation rate, forming initial nanosheets. Subsequently, to reduce the surface energy of the system, the nanosheets undergo three-dimensional self-assembly through non-covalent forces such as hydrogen bonds provided by the amino groups, ultimately forming a more thermodynamically stable nanoflower structure.

[0009] In some embodiments of the present invention, the amino-modified monobenzene ring copper-based MOFs are MOF micro-nanoflowers with a size of 0.2-2 µm and a thickness of 0.5-5 nm, which are MOF micro-nanosheets. Using hydrated copper nitrate as the metal source and diaminoterephthalic acid as the organic linker, the two self-assemble in solution through copper-oxygen coordination bonds to form a metal-organic framework. In aqueous solution, the strong coordination ability and high surface tension of water lead to explosive nucleation and greatly increase the crystal interface energy. To minimize energy, crystal growth is forced to preferentially expand rapidly laterally on the low-energy crystal plane (ab plane), while suppressing growth on the high-energy crystal plane (c-axis). This strong anisotropic growth is ultimately kinetically locked, forming nanosheets.

[0010] In another aspect of the present invention, the present invention provides a method for preparing amino-modified monophenyl ring copper-based MOFs to obtain amino-modified monophenyl ring copper-based MOFs.

[0011] In another aspect of the invention, the application of amino-modified monobenzene-cyclic copper-based MOFs is proposed. According to embodiments of the invention, the amino-modified monobenzene-cyclic copper-based MOFs are used for electrocatalytic carbon dioxide reduction.

[0012] Under the catalysis of amino-modified monobenzene ring copper-based MOFs, the stable carbon-oxygen bond of carbon dioxide molecules is broken by inputting energy, and it is then bonded to a proton (H). + ) and electrons (e - The process of combining these substances and ultimately transforming them into carbon-based products with fuel or chemical value (such as carbon monoxide, formic acid, methane, ethylene, etc.).

[0013] Amino-modified monobenzene ring copper-based MOF micro / nanoflower structures, due to their mass transfer limitation, strongly promote the carbon-carbon coupling step from intermediate carbon monoxide to oxaloyl groups, while simultaneously inhibiting further hydration or oxidation of the intermediate. Their electrocatalytic carbon dioxide reduction mainly produces ethylene, methane, and carbon monoxide. Furthermore, the amino-modified monobenzene ring copper-based MOF micro / nanoflower structures, due to their two-dimensional open structure, ensure excellent mass transfer capabilities, maintaining a relatively mild alkaline local pH. This provides conditions for more complex reactions: after carbon-carbon coupling, the intermediate oxaloyl group can further react with interfacial water molecules instead of being immediately and completely reduced. Its electrocatalytic carbon dioxide reduction mainly produces alkanes (ethylene and methane) and C2 products (ethylene, ethanol, and acetic acid).

[0014] In another aspect of the present invention, a method for preparing a flow cell cathode is provided. According to an embodiment of the present invention, the method includes the following steps: dispersing the amino-modified monobenzene ring copper-based MOFs in a mixed solution of ethanol and water, ultrasonically dispersing to form a suspension, adding a binder to prepare a catalyst slurry, then spraying it onto carbon paper, and drying the catalyst-loaded carbon paper to obtain the flow cell cathode.

[0015] In addition, the method for preparing a flow cell cathode according to the above embodiments of the present invention may also have the following additional technical features:

[0016] In some embodiments of the present invention, the volume ratio of ethanol to water is 9:1 to 4:1; the mass ratio of the amino-modified monobenzene ring copper-based MOFs to the mixed solution of ethanol and water is 1:1000 to 1:2000; the ultrasonic dispersion time is 10 to 30 min; the binder is a naphthol binder; and the loading of the catalyst slurry on the carbon paper is 0.3 to 1 mg / cm³. 2 The drying temperature is 60~80 ℃, and the drying time is 2~6 h.

[0017] In another aspect of the present invention, the present invention provides a method for preparing the flow cell cathode to obtain the flow cell cathode.

[0018] In another aspect of the invention, a flow cell is proposed. According to an embodiment of the invention, the cathode of the flow cell is used as the cathode. Specifically, a 0.5~1.5 mol / L potassium hydroxide solution is used as the electrolyte, a Fumasep anion exchange membrane is used as the ion exchange membrane, a platinum sheet electrode is used as the anode, and an Ag / AgCl electrode is used as the reference electrode.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The amino-modified monobenzene ring copper-based MOF catalyst prepared by this invention has milder overall process conditions, simpler steps, and higher reproducibility compared with noble metal-based catalysts, and has good potential for large-scale production.

[0021] 2) The amino-modified monobenzene ring copper-based MOF catalyst prepared in this invention has a unique morphology (such as the high specific surface area of ​​nanosheets, ultrathin sheets, and hierarchical pores of nanoflowers) that allows active sites to be exposed on both the inner and outer surfaces, improving the accessibility of active sites and enhancing the reaction mass transfer capability.

[0022] 3) Monobenzene ring ligands can simplify the topology and form Cu-O active sites with high exposure planes. Amino modification can optimize the electronic structure and promote CC coupling by enhancing CO2 adsorption and optimizing the electronic state of Cu sites.

[0023] 4) The amino-modified monobenzene ring copper-based MOF catalyst prepared in this invention has high selectivity for alkanes (ethylene and methane) and C2 products, with a maximum selectivity of 48% for alkanes and a maximum selectivity of 57% for C2 products (ethylene, ethanol and acetic acid).

[0024] 5) This invention precisely controls the coordination kinetics between copper ions and the ligand by selecting a rigid monobenzene ring ligand (diaminoterephthalic acid) and regulating the solvent system (ethanol / water), combined with ultrasonic-assisted dissolution and slow dropwise addition. The weak coordination of ethanol molecules facilitates the formation of nanoflower structures through slow nucleation and hydrogen bonding self-assembly, while the strong coordination and high surface tension of water lock in nanosheet structures through explosive nucleation and anisotropic growth. Attached Figure Description

[0025] Figure 1 FESEM images of amino-modified monobenzene ring copper-based MOFs micro / nanoflowers prepared in Example 1 of the present invention, wherein Figure a is a high-magnification FESEM image and Figure b is a low-magnification FESEM image.

[0026] Figure 2 Figure 1 shows FESEM images of amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 2 of this invention. Figure 2a is a high-magnification FESEM image, and Figure 2b is a low-magnification FESEM image.

[0027] Figure 3 Figure 3 shows FESEM images of amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3 of this invention. Figure 4a is a high-magnification FESEM image, and Figure 5b is a low-magnification FESEM image.

[0028] Figure 4 These are TEM images of amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3 of the present invention, wherein Figure a is a high-magnification TEM image and Figure b is a low-magnification TEM image.

[0029] Figure 5 XRD diffraction patterns of amino-modified monobenzene ring copper-based MOFs micro / nanoflowers prepared in Example 1 and amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3 of this invention.

[0030] Figure 6 Figure a shows the Faraday efficiency (Figure a) and current performance (Figure b) of the amino-modified monobenzene ring copper-based MOFs micro / nanoflowers catalyzing CO2 reduction in Example 1 of this invention.

[0031] Figure 7 Figure a shows the Faraday efficiency (Figure a) and current performance (Figure b) of the amino-modified monobenzene ring copper-based MOFs micro / nanosheets catalyzing CO2 reduction in Example 2 of this invention.

[0032] Figure 8 Figure a shows the Faraday efficiency (Figure a) and current performance (Figure b) of the amino-modified monobenzene ring copper-based MOFs micro / nanosheets catalyzing CO2 reduction in Example 3 of this invention. Detailed Implementation

[0033] 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 the 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.

[0034] Example 1

[0035] A method for preparing amino-modified monobenzene ring copper-based MOF micro / nanoflowers includes the following steps:

[0036] (1) Dissolve 1.028 g of copper nitrate monohydrate in 20 mL of ethanol solution and sonicate for 15 min to form solution A;

[0037] (2) Dissolve 181.15 mg of diaminoterephthalic acid in 30 mL of ethanol solution and sonicate for 10 min to form solution B;

[0038] (3) Solution A was slowly added dropwise to solution B, and the reaction was stirred at room temperature for 0.5 h. After washing twice by centrifugation with ethanol and drying, amino-modified monobenzene ring copper-based MOFs micro-nano flowers were obtained.

[0039] like Figure 1 As shown, amino-modified monobenzene ring copper-based MOFs micro-nanoflowers are assembled from a large number of 1-5 nm ultrathin nanosheets with a size of 0.2-2 µm. Through a three-dimensional hierarchical porous structure, while maintaining the exposure of highly active sites, the overall mass transfer efficiency can be greatly optimized, and the stability and anti-agglomeration ability of the structure can be enhanced.

[0040] Example 2

[0041] A method for preparing amino-modified monobenzene ring copper-based MOFs micro / nanosheets includes the following steps:

[0042] (1) Dissolve 205.57 mg of copper nitrate monohydrate in 20 mL of deionized water and sonicate for 15 min to form solution A;

[0043] (2) Dissolve 181.15 mg of diaminoterephthalic acid in 30 mL of deionized water and sonicate for 10 min to form solution B;

[0044] (3) Solution A was slowly added dropwise to solution B, and the reaction was stirred at room temperature for 0.5 h. After centrifugation and washing twice with deionized water, amino-modified monobenzene ring copper-based MOFs micro / nanosheets were obtained after drying.

[0045] like Figure 2 As shown, the amino-modified monobenzene ring copper-based MOFs micro / nanosheets have a size of 0.2–2 µm and a thickness of 0.5–3 nm. The ultrathin MOFs micro / nanosheets can maximize the exposure of active sites and minimize the optimized mass transfer / electron transport distance.

[0046] Example 3

[0047] A method for preparing amino-modified monobenzene ring copper-based MOFs micro / nanosheets includes the following steps:

[0048] (1) Dissolve 205.57 mg of copper nitrate monohydrate in 20 mL of deionized water and sonicate for 15 min to form solution A;

[0049] (2) Dissolve 1027.85 mg of diaminoterephthalic acid in 30 mL of deionized water and sonicate for 10 min to form solution B;

[0050] (3) Solution A was slowly added dropwise to solution B, and the reaction was stirred at room temperature for 0.5 h. After centrifugation and washing twice with deionized water, amino-modified monobenzene ring copper-based MOFs micro / nanosheets were obtained after drying.

[0051] Figure 3 These are FESEM images of the amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3. Figure 4 The image shows a TEM image of the amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3. It can be seen that the size of the MOFs micro / nanosheets is 0.2~2 µm and the thickness is 0.5~5 nm. The ultrathin MOFs micro / nanosheets can maximize the exposure of active sites and minimize the optimized mass transfer / electron transport distance.

[0052] Figure 5 The figures show the XRD diffraction patterns of the amino-modified monobenzene ring copper-based MOFs micro / nanoflowers prepared in Example 1 and the amino-modified monobenzene ring copper-based MOFs micro / nanosheets prepared in Example 3. As can be seen from the figures, the XRD diffraction patterns of the amino-modified monobenzene ring copper-based MOFs micro / nanoflowers and micro / nanosheets are basically consistent, both showing a crystalline structure, and the monobenzene ring copper-based MOFs micro / nanosheets have a higher degree of crystallinity.

[0053] Application Example 1

[0054] A method for preparing a flow cell includes the following steps:

[0055] (1) Weigh 20 mg of the amino-modified monobenzene ring copper-based MOFs micro / nano flower powder prepared in Example 1, disperse it in 10 mL of a mixed solution of ethanol and water (volume ratio of ethanol to water is 4:1), add 40 μL of D520 perfluorosulfonic acid solution, and sonicate for 15 min to completely disperse the catalyst powder in the mixed solution to prepare a catalyst slurry.

[0056] (2) The catalyst slurry was drop-sprayed onto 2 cm × 4 cm carbon paper with a loading of 0.5 mg / cm. 2 The carbon paper loaded with the catalyst after drying is then placed in a vacuum drying oven at 70°C for 2 hours. This dried carbon paper is the cathode of the flow cell.

[0057] (3) The carbon paper loaded with the catalyst after drying is used as the cathode of the flow cell, the platinum sheet electrode is used as the anode, the Ag / AgCl electrode is used as the reference electrode, the 1.0 mol / L potassium hydroxide solution is used as the electrolyte, and the fumasep anion membrane is used as the ion exchange membrane.

[0058] Electrocatalytic performance was tested within the voltage range of -1.0 to -2.4 V vs RHE. The products of its electrocatalysis of carbon dioxide were carbon monoxide, methane, and ethylene.

[0059] like Figure 6 As shown, the amino-modified monobenzene ring copper-based MOFs micro / nanoflowers exhibit a selectivity of up to 44.7% for catalytic conversion of CO2 into alkanes.

[0060] Application Example 2

[0061] A method for preparing a flow cell includes the following steps:

[0062] (1) Weigh 20 mg of the amino-modified monobenzene ring copper-based MOFs micro / nanosheet powder prepared in Example 2, disperse it in 10 mL of a mixed solution of ethanol and water (volume ratio of ethanol to water is 4:1), add 40 μL of 5% D520 perfluorosulfonic acid solution, and sonicate for 15 min to completely disperse the catalyst powder in the mixed solution to prepare a catalyst slurry.

[0063] (2) The catalyst slurry was drop-sprayed onto 2 cm × 4 cm carbon paper with a loading of 0.5 mg / cm. 2 The carbon paper loaded with the catalyst after drying is then placed in a vacuum drying oven at 70°C for 2 hours. This dried carbon paper is the cathode of the flow cell.

[0064] (3) The carbon paper loaded with the catalyst after drying is used as the cathode of the flow cell, the platinum sheet electrode is used as the anode, the Ag / AgCl electrode is used as the reference electrode, the 1.0 mol / L potassium hydroxide solution is used as the electrolyte, and the fumasep anion membrane is used as the ion exchange membrane.

[0065] Electrocatalytic performance was tested within the voltage range of -1.0 to -2.4 V vs RHE. The products of its electrocatalysis of carbon dioxide were carbon monoxide, methane, ethylene, ethanol, and acetic acid.

[0066] like Figure 7 As shown, the amino-modified monobenzene ring copper-based MOFs micro / nanosheets exhibited a selectivity of up to 43.6% for catalytic conversion of CO2 to alkanes and up to 56.7% for catalytic conversion of CO2 to C2 products.

[0067] Application Example 3

[0068] A method for preparing a flow cell includes the following steps:

[0069] (1) Weigh 20 mg of the amino-modified monobenzene ring copper-based MOFs micro / nanosheet powder prepared in Example 3, disperse it in 10 mL of a mixed solution of ethanol and water (volume ratio of ethanol to water is 4:1), add 40 μL of 5% D520 perfluorosulfonic acid solution, and sonicate for 15 min to completely disperse the catalyst powder in the mixed solution to prepare a catalyst slurry.

[0070] (2) The catalyst slurry was drop-sprayed onto 2 cm × 4 cm carbon paper with a loading of 0.5 mg / cm. 2 The carbon paper loaded with the catalyst after drying is then placed in a vacuum drying oven at 70°C for 2 hours. This dried carbon paper is the cathode of the flow cell.

[0071] (3) The carbon paper loaded with the catalyst after drying is used as the cathode of the flow cell, the platinum sheet electrode is used as the anode, the Ag / AgCl electrode is used as the reference electrode, the 1.0 mol / L potassium hydroxide solution is used as the electrolyte, and the fumasep anion membrane is used as the ion exchange membrane.

[0072] Electrocatalytic performance was tested within the voltage range of -1.0 to -2.4 V vs RHE. The products of its electrocatalysis of carbon dioxide were carbon monoxide, methane, ethylene, ethanol, and acetic acid.

[0073] like Figure 8 As shown, amino-modified monobenzene ring copper-based MOFs micro / nanosheets can achieve a selectivity of up to 47.5% for catalytic conversion of CO2 to alkanes and up to 47.8% for catalytic conversion of CO2 to C2 products.

[0074] 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 structure of the present 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 amino-modified monobenzene ring copper-based MOFs, characterized in that, Includes the following steps: A copper nitrate monohydrate solution was added dropwise to a diaminoterephthalic acid solution, the reaction was stirred, and the product was centrifuged, washed, and dried to obtain amino-modified monobenzene ring copper-based MOFs. The copper nitrate monohydrate solution is obtained by dissolving copper nitrate monohydrate in a solvent, and the concentration of the copper nitrate monohydrate solution is 0.02~0.4 mol / L. The diaminoterephthalic acid solution is obtained by dissolving diaminoterephthalic acid in a solvent, and the concentration of the diaminoterephthalic acid solution is 0.025~0.05 mol / L; The solvent is ethanol or deionized water; The stirring reaction was carried out at room temperature for 0.5 to 2 hours.

2. The method for preparing amino-modified monobenzene ring copper-based MOFs according to claim 1, characterized in that: The copper nitrate monohydrate is dissolved in the solvent by ultrasonic dissolution, and the ultrasonic time is 10~30 min. The diaminoterephthalic acid is dissolved in the solvent by ultrasonic dissolution for 5-20 min. The centrifugal washing is performed using ethanol or deionized water, and the number of centrifugal washing cycles is 2 to 3.

3. The method for preparing amino-modified monobenzene ring copper-based MOFs according to claim 1, characterized in that: When the solvent is ethanol, the amino-modified monobenzene ring copper-based MOFs are micro-nano flowers of 0.2~2 µm.

4. The method for preparing amino-modified monobenzene ring copper-based MOFs according to claim 1, characterized in that: When the solvent is deionized water, the amino-modified monobenzene ring copper-based MOFs are MOF micro / nanosheets with a size of 0.2~2 µm and a thickness of 0.5~5 nm.

5. The amino-modified monophenyl ring copper-based MOFs prepared by the method of any one of claims 1-4.

6. The application of the amino-modified monobenzene ring copper-based MOFs according to claim 5, characterized in that: The amino-modified monobenzene ring copper-based MOFs are used for electrocatalytic carbon dioxide reduction.

7. A method for preparing a flow cell cathode, characterized in that, The process includes the following steps: dispersing the amino-modified monobenzene ring copper-based MOFs of claim 5 in a mixed solution of ethanol and water, preparing a suspension by ultrasonic dispersion, adding a binder to prepare a catalyst slurry, then spraying it onto carbon paper, and drying the carbon paper loaded with the catalyst to obtain the cathode of the flow cell.

8. The method for preparing a flow cell cathode according to claim 7, characterized in that: The volume ratio of ethanol to water is 9:1 to 4:1; The mass ratio of the amino-modified monobenzene ring copper-based MOFs to the mixed solution of ethanol and water is 1:1000 to 1:2000. The ultrasonic dispersion time is 10~30 min; The adhesive is a naphthol adhesive; The catalyst slurry loading on the carbon paper is 0.3~1 mg / cm³. 2 ; The drying temperature is 60~80 ℃, and the drying time is 2~6 h.

9. A flow cell cathode prepared by the preparation method of claim 7.

10. A flow battery, characterized in that: The flow cell cathode of claim 9 is used as the cathode.

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