Multi-dimensional regulation and control metal organic framework composite electrode and preparation method and application thereof

Abstract

The invention relates to a multi-dimensional regulation metal organic framework composite electrode and a preparation method and application thereof, and the preparation method comprises the following steps: (1) placing a substrate in an electroplating solution, and carrying out pulse electrochemical deposition on the substrate to obtain a metal organic framework composite precursor; (2) putting the metal organic framework composite precursor obtained in the step (1) into conductive filler dispersion liquid, and performing ultrasonic treatment to obtain a metal organic framework composite precursor loaded with conductive filler; and (3) carrying out heat treatment on the metal organic framework composite precursor loaded with the conductive filler obtained in the step (2) to obtain the multi-dimensional regulation metal organic framework composite electrode, the on-off time ratio Ton / Toff of the pulse electrochemical deposition in the step (1) is (1-3): 1. The structure of the composite electrode is regulated and controlled through a pulse electrochemical deposition process, the composite electrode with excellent conductivity, high electrocatalytic activity and high stability is obtained, and the requirements of the fields of electrocatalysis, energy storage and the like are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical functional materials, and particularly relates to a multi-dimensional controlled metal organic framework composite electrode and a preparation method and application thereof. BACKGROUND

[0002] Metal organic framework (MOF) material is a kind of porous crystal material with periodic network structure formed by self-assembly of metal ions or metal clusters and organic ligands through coordination bonds. With its ultra-high specific surface area, adjustable pore size and structure composition, rich active sites and diverse topological structure, MOF material shows great application potential in the fields of electrocatalysis, energy storage, gas adsorption and separation, environmental pollutant treatment, etc., and has become one of the research hotspots in the field of material science.

[0003] However, in the actual preparation and application process of MOF material, there are still many problems to be solved in the traditional preparation method.

[0004] For example, the morphology and structure regulation has great limitations. Specifically, the traditional solvothermal method, hydrothermal method, constant potential electrodeposition method, etc. are difficult to achieve the desired preparation of MOF material. For example, the solvothermal method usually relies on high temperature and high pressure conditions, and the crystal growth rate is difficult to control during the reaction process, which easily leads to the agglomeration of MOF material and poor morphology uniformity; the constant potential electrodeposition method is difficult to adjust the kinetics balance of ion diffusion and crystal growth due to the continuous application of constant voltage, and the thickness of MOF film layer is uneven and the grain orientation is disorderly, which cannot meet the needs of MOF material in different application scenarios.

[0005] In addition, the solvent system has poor adaptability. Specifically, in the traditional preparation process, the solvent system usually uses single solvent or simple binary mixed solvent, such as pure DMF, DMF-water mixed solvent, etc. Such solvent system has limited effect on the solubility, dispersibility and coordination reaction rate of metal ions and organic ligands, and it is difficult to realize the precise adjustment of MOF material crystal form and pore size distribution. At the same time, the single solvent system also has problems of strong volatility, high toxicity, low recycling rate, etc., which does not meet the needs of green chemistry and industrial production.

[0006] In addition, the stability of MOF material is insufficient. Specifically, pure MOF material usually has problems of poor electrical conductivity, poor chemical stability and mechanical stability. In the process of electrocatalytic reaction, pure MOF material is easy to cause the decrease of catalytic activity due to the large charge transfer resistance; in the acidic or alkaline reaction environment, the coordination bond of MOF material is easy to break, which leads to the collapse of structure and affects the service life. In addition, in the process of pollutant adsorption treatment, the adsorption capacity of pure MOF material is limited by the pore size and surface chemical state, and the adsorbed MOF material is difficult to regenerate and utilize, which increases the application cost.

[0007] The preparation of the existing MOF-based composite electrode mostly uses physical mixing method, coating method and the like to mix the MOF material and the conductive filler simply and then coat on the surface of the conductive substrate. Such method has the problems of weak bonding force between the MOF material and the conductive filler and the substrate, uneven dispersion and the like, which leads to the phenomenon of active material falling off in the charging and discharging or catalytic reaction process of the composite electrode, and significantly reduces the cycle stability and service life of the electrode.

[0008] The pulse electroplating technology, as an advanced electrochemical preparation method, can realize the time-sharing regulation of nucleation rate and growth rate by periodically applying pulse voltage signals, and exhibits unique advantages in the morphology and structure regulation of metals, alloys and composite materials.

[0009] However, the application of the pulse electroplating technology in the preparation of the MOF material is still in the initial stage, and the existing researches mostly focus on the influence of single pulse parameter on the MOF material, and fail to synergistically regulate the pulse parameters and the solvent system, surface modifier and other factors, so as to realize the multi-dimensional and all-round regulation of the MOF material. In addition, the application research on the optimization of the composite process of the MOF material prepared by the pulse electroplating and the conductive filler and the substrate is also relatively scarce.

[0010] Therefore, how to develop a multi-dimensional regulation metal organic framework composite electrode with high conductivity, good electrocatalytic performance (electrocatalytic activity) and good stability and a preparation method thereof has become a problem to be solved at present. SUMMARY

[0011] To solve the above technical problems, the purpose of the present application is to provide a multi-dimensional regulation metal organic framework composite electrode and a preparation method and application thereof. The multi-dimensional regulation metal organic framework composite electrode regulates the structure of the multi-dimensional regulation metal organic framework composite electrode by synergistically optimizing the composition of the electroplating solution, the pulse electrochemical deposition parameters, the ratio of the conductive filler and the solvent system, so as to obtain a composite electrode with excellent conductivity, high electrocatalytic activity and strong stability, thereby meeting the application requirements in the fields of electrocatalysis and energy storage.

[0012] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0013] In a first aspect, the present application provides a preparation method of a multi-dimensional regulation metal organic framework composite electrode, which comprises the following steps:

[0014] (1) placing a substrate in an electroplating solution and performing pulse electrochemical deposition on the substrate to obtain a metal organic framework composite precursor;

[0015] (2) The metal-organic framework composite precursor obtained in step (1) is placed in a conductive filler dispersion and sonicated to obtain a metal-organic framework composite precursor loaded with conductive filler.

[0016] (3) The metal-organic framework composite precursor loaded with conductive filler obtained in step (2) is heat-treated to obtain the multidimensional regulated metal-organic framework composite electrode.

[0017] The electroplating solution in step (1) includes a metal salt, an organic ligand, and a solvent; the on / off time ratio of the pulsed electrochemical deposition in step (1) is T. on / T off The ratio is 1-3:1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1 or 3:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] This invention employs a pulsed electrochemical deposition process to promote the nucleation of metal ions on the substrate surface through electrochemical reduction, thereby enhancing the adhesion between the metal-organic framework composite layer and the nickel foam substrate. Furthermore, the coating effect of the conductive layer further improves the chemical and mechanical stability of the material, effectively preventing the shedding of active materials and extending the electrode's lifespan. The preparation process of this invention is simple and operates under mild conditions, making it suitable for large-scale industrial production.

[0019] In this invention, "T" on "T" indicates the energizing time, during which metal ions are reduced to nuclei on the substrate surface; off "T" indicates the power-off time. During this time, metal ions and ligands in the electroplating solution diffuse to the nucleus surface, completing crystal growth. If the on / off time ratio is less than 1:1, the on-time is too short, resulting in insufficient nucleation and making it difficult to form a continuous MOF layer; if T on / T off When the ratio is greater than 3:1, the energizing time is too long, and nucleation and growth occur simultaneously, which can easily lead to crystal aggregation, uneven film thickness, and even irregular block structures.

[0020] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0021] Preferably, the substrate in step (1) is nickel foam, copper foam, cobalt foam, or metal foil.

[0022] This invention preferably uses nickel foam as the electrochemical electrode substrate. Nickel foam has a three-dimensional porous network structure with a porosity of over 90% and a large specific surface area, which can provide attachment sites for the growth of MOF composite layers, while also facilitating electrolyte penetration and gas diffusion.

[0023] Before placing the substrate in the electroplating solution for pulsed electrochemical deposition in step (1) of this invention, the substrate is pretreated: ultrasonic cleaning with acetone or ethanol for 20-40 minutes is used to remove oil, organic impurities, and processing residues from the surface of the nickel foam substrate. The microfluidic field generated by ultrasonic vibration can penetrate deep into the pores, avoiding the influence of impurity residues on the subsequent deposition effect. The cleaned nickel foam is then immersed in a 1 mol / L-3 mol / L hydrochloric acid or nitric acid aqueous solution for 5-15 minutes to remove the nickel oxide layer on the surface and expose the fresh nickel surface, providing active sites for the interfacial bonding of metal ions and the substrate. Drying in an inert atmosphere at 60℃-80℃ for 1-2 hours removes moisture from the substrate and prevents the fresh nickel surface from oxidizing again.

[0024] Preferably, in the pulsed electrochemical deposition process, the substrate is used as the working electrode, the platinum mesh as the counter electrode, and the Ag / AgCl electrode as the reference electrode. The working electrode and the counter electrode are parallel and spaced apart in the range of 1 cm to 15 cm.

[0025] Preferably, the voltage of the pulsed electrochemical deposition in step (1) is from -2.0V to -1.2V, for example, it can be -2.0V, -1.9V, -1.8V, -1.7V, -1.6V, -1.5V, -1.4V, -1.3V or -1.2V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] This invention aims to promote the nucleation of metal ions on the surface of a nickel foam substrate through electrochemical reduction by further controlling the voltage of pulsed electrochemical deposition to -2.0V to -1.2V. If the voltage is too negative (below -2.0V), the reduction rate of metal ions is too fast, which can easily lead to amorphous deposition or precipitation of elemental metals, destroying the coordination structure of the MOF. If the voltage is too positive (above -1.2V), the reduction driving force is insufficient, the nucleation rate is slow, and it is difficult to form a continuous MOF composite layer. Around -1.6V is the preferred value, at which the reduction of metal ions and the coordination reaction of ligands proceed simultaneously, forming a stable MOF precursor.

[0027] Preferably, the temperature of the pulsed electrochemical deposition in step (1) is 30℃-60℃, for example, it can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃ or 60℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] This invention further controls the pulsed electrochemical deposition temperature to 30℃-60℃, which is the optimal range for the synergistic action of coordination reaction and electrochemical deposition. If the temperature is below 30℃, the coordination reaction rate between metal ions and ligands is too slow, resulting in low deposition efficiency and incomplete MOF crystal growth. If the temperature is above 60℃, the solvent evaporation rate accelerates, leading to unstable electroplating solution concentration and potentially causing ligand decomposition or metal ion hydrolysis, affecting the crystal structure of the MOF. Around 45℃ is the preferred temperature, at which the coordination reaction and electrodeposition rate reach equilibrium, resulting in a MOF composite layer with uniform morphology and stable structure.

[0029] Preferably, the pulsed electrochemical deposition time is 30 min to 100 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min or 100 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the metal salt includes nickel salt, cobalt salt, and copper salt.

[0031] Preferably, the organic ligands include terephthalic acid, trimesic acid, and furanyl dicarboxylic acid.

[0032] Preferably, the electroplating solution comprises 5wt%-8wt% nickel salt, based on a total mass of 100wt%, for example, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, or 8wt%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0033] Preferably, the electroplating solution comprises 1wt%-2wt% of cobalt salt, based on a total mass of 100wt%, for example, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, or 2wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the electroplating solution comprises 0.2wt%-0.5wt% copper salt, based on a total mass of 100wt%, for example, 0.2wt%, 0.3wt%, 0.4wt%, or 0.5wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the electroplating solution comprises 1 wt% to 2 wt% of terephthalic acid, based on a total mass of 100 wt%. For example, it may be 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, or 2 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the electroplating solution comprises 1 wt% to 2.5 wt% of pyromellitic acid, based on a total mass of 100 wt%. For example, it may be 1 wt%, 1.5 wt%, 2 wt%, or 2.5 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the electroplating solution comprises 0.5wt%-1.5wt% furanyl dicarboxylic acid, based on a total mass of 100wt%, for example, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, or 1.5wt%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0038] Preferably, the electroplating solution comprises 0.1wt%-3wt% of a surfactant, based on a total mass of 100wt%, for example, 0.1wt%, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, or 3wt%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0039] In this invention, the electroplating solution selects nickel salt, cobalt salt, and copper salt to form a Ni-Co-Cu ternary metal ion system. The multi-metal ions (Ni, Co, Cu) synergistically interact with various organic ligands to form abundant active sites. Combined with high specific surface area, this enhances the electrocatalytic reaction rate and catalytic efficiency. Nickel ions are the main metal center of the MOF material, providing the basic coordination framework and electrocatalytic active sites. Their content is controlled at 5wt%-8wt%, ensuring the growth thickness of the MOF layer while avoiding ion aggregation due to excessive concentration. The introduction of cobalt ions can adjust the electronic structure of the MOF material and improve charge transfer efficiency. A content of 1wt%-2wt% can form a synergistic catalytic effect with nickel ions; excessive concentration will lead to crystal distortion. Copper ions, as an auxiliary active component, have an ionic radius similar to nickel and cobalt ions and can partially replace nickel / cobalt ions in the crystal lattice, forming defect structures and increasing the number of active sites. A low content of 0.2wt%-0.5wt% is sufficient to achieve the optimized effect; excessive amounts will destroy the periodic structure of the MOF. Apart from the Ni-Co-Cu ternary metal ion system, other metal components (such as Mn, Zn, etc.) have poor coordination compatibility with organic ligands, making it impossible to construct a stable and efficient structure, thus destroying the ternary synergistic effect and resulting in a significant decrease in conductivity, catalytic activity and stability.

[0040] On the other hand, the electroplating solution of this invention employs a composite ligand system of terephthalic acid (1-2%), trimesic acid (1-2.5%), and furanyl dicarboxylic acid (0.5-1.5%). Compared to single ligands, the composite ligand can regulate the topological structure of the MOF through different coordination modes (such as bridging coordination of dicarboxylic acids and nodal coordination of tricarboxylic acids). Terephthalic acid, as a linear ligand, can construct layered or columnar structures, providing a basic porous framework; trimesic acid, as a trifurcation ligand, can introduce a three-dimensional cross-linked structure, enhancing the structural stability of the MOF; the furan ring in furanyl dicarboxylic acid has electron-donating properties, enabling stronger coordination with metal ions, while its heteroatom structure can optimize the surface electron distribution of the MOF, enhancing electrocatalytic activity. The content ratio of the three ligands is controlled to ensure the kinetic balance of the coordination reaction: when the terephthalic acid content is below 1%, structural defects easily appear in the MOF layer; when it is above 2%, excessive ligand accumulation occurs, affecting crystal growth. The content ranges of pyromellitic acid and furanyl dicarboxylic acid are respectively matched to the needs of three-dimensional structure construction and electronic structure optimization. The three work together to form a MOF structure with both high specific surface area and abundant active sites.

[0041] In this invention, the surfactant in the electroplating solution reduces interfacial tension by adsorbing onto the surface of MOF crystals, inhibiting excessive crystal growth, while improving the dispersion of metal ions and ligands.

[0042] Preferably, the surfactant comprises any one or a combination of at least two of hexadecyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), or sodium dodecylbenzenesulfonate (SDBS). Typical but non-limiting combinations include combinations of hexadecyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP), combinations of polyvinylpyrrolidone (PVP) and sodium dodecylbenzenesulfonate (SDBS), combinations of hexadecyltrimethylammonium bromide (CTAB) and sodium dodecylbenzenesulfonate (SDBS), and combinations of hexadecyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), and sodium dodecylbenzenesulfonate (SDBS).

[0043] In this invention, the surfactant in the electroplating solution reduces interfacial tension and inhibits excessive crystal growth by adsorbing onto the surface of MOF crystals, while simultaneously improving the dispersibility of metal ions and ligands. Hexadecyltrimethylammonium bromide (CTAB), as a cationic surfactant, can bind to the negatively charged sites on the MOF crystal surface, forming a steric hindrance effect; polyvinylpyrrolidone (PVP), as a nonionic surfactant, has a long-chain structure that can wrap around the crystal surface, further preventing aggregation.

[0044] Preferably, the surfactant comprises cetyltrimethylammonium bromide and polyvinylpyrrolidone in a mass ratio of 1:2-3, for example, 1:2, 1:2.5 or 1:3, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0045] The present invention further optimizes the CTAB and PVP composite system with a mass ratio of 1:2-3. At this ratio, the synergistic effect of the two surfactants is the strongest, which can ensure the dispersion effect and avoid the subsequent cleaning difficulties or the impact on the pore structure of MOF due to excessive surfactant. Sodium dodecylbenzenesulfonate, as an alternative anionic surfactant, is suitable for scenarios with specific requirements for surface charge. Its mechanism of action is similar to that of CTAB and can be selected according to actual needs.

[0046] Preferably, the solvent comprises any one or a combination of at least two of N,N-dimethylformamide (DMF), water, ethanol, or ethylene glycol. Typical but non-limiting combinations include combinations of N,N-dimethylformamide (DMF) and water, combinations of water and ethylene glycol, combinations of water, ethanol, and ethylene glycol, combinations of N,N-dimethylformamide (DMF), water, and ethylene glycol, combinations of N,N-dimethylformamide (DMF) and ethylene glycol, and combinations of N,N-dimethylformamide (DMF), ethanol, and ethylene glycol.

[0047] Preferably, the solvent comprises 40wt%-55wt% of N,N-dimethylformamide, based on a total mass of 100wt%, for example, 40wt%, 42wt%, 45wt%, 48wt%, 50wt%, 52wt%, or 55wt%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0048] Preferably, the solvent comprises 25wt%-40wt% water, based on a total mass of 100wt%, for example, 25wt%, 30wt%, 32wt%, 35wt%, or 40wt%, but is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0049] Preferably, the solvent comprises 12wt%-18wt% ethanol, based on a total solvent mass of 100wt%, for example, 12wt%, 14wt%, 15wt% or 18wt%, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0050] Preferably, the solvent comprises 5 wt% to 8 wt% ethylene glycol, based on a total mass of 100 wt%, for example, 5 wt%, 6 wt%, 7 wt% or 8 wt%, but not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0051] This invention further employs a mixture of multiple solvents, overcoming the limitations of traditional single or binary solvents. Dimethyl sulfoxide (DMF), a classic solvent for MOF preparation, exhibits excellent solubility for organic ligands, promoting smooth coordination reactions. The introduction of water reduces solvent costs and toxicity, while also regulating solution polarity and optimizing crystal growth kinetics. Ethanol, as a co-solvent, improves the dispersibility of metal ions and reduces agglomeration. The addition of ethylene glycol regulates solution viscosity, slows ion diffusion rates, and results in more uniform MOF crystal growth. The weight ratios of each solvent are optimized: the dominant role of DMF ensures ligand solubility, the water-ethanol ratio balances dispersibility and reaction rate, and the low content of ethylene glycol avoids mass transfer obstruction caused by excessive viscosity. This multi-solvent system not only improves the morphological uniformity of MOF materials but also reduces the volatility and toxicity of individual solvents, aligning with green chemistry principles.

[0052] Preferably, the nickel salt comprises any one or a combination of at least two of nickel nitrate, nickel sulfate, or nickel chloride. Typical but non-limiting combinations include combinations of nickel nitrate and nickel sulfate, combinations of nickel sulfate and nickel chloride, combinations of nickel nitrate and nickel chloride, and combinations of nickel nitrate, nickel sulfate, and nickel chloride, with nickel nitrate being the most preferred.

[0053] Preferably, the cobalt salt comprises any one or a combination of at least two of cobalt nitrate, cobalt sulfate, or cobalt chloride. Typical but non-limiting combinations include combinations of cobalt nitrate and cobalt sulfate, cobalt sulfate and cobalt chloride, cobalt nitrate and cobalt chloride, and combinations of cobalt nitrate, cobalt sulfate, and cobalt chloride, with cobalt nitrate being the most preferred.

[0054] Preferably, the copper salt comprises any one or a combination of at least two of copper chloride, copper sulfate, or copper nitrate. Typical but non-limiting combinations include combinations of copper chloride and copper sulfate, copper sulfate and copper nitrate, copper chloride and copper nitrate, and combinations of copper chloride, copper sulfate, and copper nitrate, with copper chloride being the most preferred.

[0055] Preferably, based on the total mass of the conductive filler dispersion in step (2) being 100wt%, the conductive filler dispersion includes 8wt%-12wt% conductive filler, with the remainder being the first solvent, for example, it can be 8wt%, 9wt%, 10wt%, 11wt% or 12wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0056] Preferably, the conductive filler comprises any one or a combination of at least two of carbon nanotubes, graphene, or carbon black. Typical but non-limiting combinations include combinations of carbon nanotubes and graphene, graphene and carbon black, carbon nanotubes and carbon black, and combinations of carbon nanotubes, graphene, and carbon black. Preferably, it is a combination of carbon nanotubes and graphene.

[0057] In this invention, high-performance conductive fillers such as carbon nanotubes and graphene are selected to form a conductive layer, which forms a continuous conductive network with the metal-organic framework composite layer, thereby reducing charge transfer resistance and improving electrode conductivity.

[0058] Preferably, the first solvent includes water and / or ethanol.

[0059] Preferably, based on a total mass of 100wt% of the conductive filler dispersion, the conductive filler dispersion includes 3wt%-9wt% of carbon nanotubes, for example, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt% or 9wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0060] Preferably, based on a total mass of 100wt% of the conductive filler dispersion, the conductive filler dispersion comprises 4wt%-8wt% of graphene and the balance being a first solvent, for example, it can be 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0061] The first solvent is water and ethanol in a weight ratio of 1-3:1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1 or 3:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] Preferably, after step (1) and before step (2), the metal-organic framework composite precursor obtained in step (1) is further cleaned and dried.

[0063] Preferably, the cleaning process includes sequentially spraying the metal-organic framework composite precursor with N,N-dimethylformamide, ethanol, and deionized water at a pressure of 0.3 MPa-0.45 MPa and for each cleaning session lasting 10-15 minutes.

[0064] Preferably, the ultrasound duration is 30-60 minutes, for example, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0065] Preferably, the heat treatment temperature in step (3) is 200℃-400℃, for example, it can be 200℃, 250℃, 300℃, 350℃ or 400℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0066] Preferably, the heat treatment time is 3h-5h, for example, it can be 3h, 3.5h, 4h, 4.5h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0067] Preferably, the heating rate of the heat treatment is 2℃ / min-5℃ / min, for example, it can be 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min or 5℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0068] As a preferred embodiment of the preparation method of the present invention, the preparation method includes the following steps:

[0069] (I) Immerse the nickel foam substrate in acetone or ethanol and ultrasonically clean it for 20 min-40 min; then immerse the nickel foam substrate in a 1 mol / L-3 mol / L hydrochloric acid or nitric acid aqueous solution for 5 min-15 min; rinse with deionized water until neutral; and dry in an inert atmosphere at 60℃-80℃ for 1 h-2 h to obtain a clean nickel foam substrate.

[0070] (II) The foamed nickel substrate obtained in step (I) is placed in an electroplating solution. The foamed nickel substrate is used as the working electrode, the platinum mesh is used as the counter electrode, and the Ag / AgCl electrode is used as the reference electrode. Pulse electrochemical deposition is performed on the substrate to obtain a metal-organic framework composite precursor.

[0071] The electroplating solution comprises, based on a total mass of 100wt%, 5wt%-8wt% nickel salt, 1wt%-2wt% cobalt salt, 0.2wt%-0.5wt% copper salt, 1wt%-2wt% terephthalic acid, 1wt%-2.5wt% trimesic acid, 0.5wt%-1.5wt% furanyl dicarboxylic acid, and 0.1wt%-3wt% surfactant and solvent, with a total mass of 100wt% of the electroplating solution.

[0072] The surfactant comprises hexadecyltrimethylammonium bromide and polyvinylpyrrolidone in a mass ratio of 1:2-3;

[0073] Based on a total solvent mass of 100 wt%, the solvent comprises 40 wt%-55 wt% N,N-dimethylformamide, 25 wt%-40 wt% water, 12 wt%-18 wt% ethanol and 5 wt%-8 wt% ethylene glycol;

[0074] The voltage for pulsed electrochemical deposition ranges from -2.0V to -1.2V, and the on / off time ratio of pulsed electrochemical deposition is T. on / Toff The ratio is 1-3:1, and the total time for pulsed electrochemical deposition is 30-100 min;

[0075] (III) The metal-organic framework composite precursor was sprayed and cleaned with N,N-dimethylformamide, ethanol and deionized water. The spraying pressure was 0.3MPa-0.45MPa and the cleaning time was 10min-15min each time. Then it was dried.

[0076] (IV) The dried metal-organic framework composite precursor was placed in a conductive filler dispersion and sonicated for 30-60 minutes to obtain a metal-organic framework composite precursor loaded with conductive filler.

[0077] Based on a total mass of 100wt% for the conductive filler dispersion, the conductive filler dispersion comprises 8wt%-12wt% conductive filler, with the remainder being the first solvent;

[0078] (V) Under nitrogen protection, the metal-organic framework composite precursor loaded with conductive filler obtained in step (IV) is heated to 200℃-400℃ at a heating rate of 2℃ / min-5℃ / min for 3h-5h to obtain the multidimensional regulated metal-organic framework composite electrode.

[0079] In a second aspect, the present invention provides a multidimensionally regulated metal-organic framework composite electrode, which is prepared according to the preparation method described in the first aspect.

[0080] The multi-dimensional regulated metal-organic framework composite electrode provided by this invention has synergistic effects among its layers, resulting in high conductivity, excellent electrocatalytic performance, and good stability.

[0081] Preferably, the multidimensional regulated metal-organic framework composite electrode includes a substrate, a metal-organic framework composite layer loaded on the surface of the substrate, and a conductive layer attached to the surface of the metal-organic framework composite layer.

[0082] Preferably, the thickness of the substrate is 0.5mm-10mm, for example, it can be 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0083] The present invention preferably uses a nickel foam substrate with a thickness of 0.5 mm to 10 mm, which balances structural strength and electrochemical performance.

[0084] Preferably, the thickness of the metal-organic framework composite layer is 10μm-30μm, for example, it can be 10μm, 15μm, 20μm, 25μm or 30μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0085] Preferably, the thickness of the conductive layer is 3nm-50nm, for example, it can be 3nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0086] Preferably, the specific surface area of ​​the multi-dimensional regulated metal-organic framework composite electrode is 500 m². 2 / g-3000m 2 / g, for example, could be 500m 2 / g, 1000m 2 / g, 1500m 2 / g、2000m 2 / g、2500m 2 / g or 3000m 2 / g, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0087] Thirdly, the present invention provides an application of the multidimensionally regulated metal-organic framework composite electrode as described in the second aspect, wherein the multidimensionally regulated metal-organic framework composite electrode is used in the fields of electrocatalysis, energy storage or environmental pollutant treatment.

[0088] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0089] Compared with the prior art, the present invention has at least the following beneficial effects:

[0090] (1) This invention employs a pulsed electrochemical deposition process to promote the nucleation of metal ions on the substrate surface through electrochemical reduction, thereby enhancing the bonding force between the metal-organic framework composite layer and the nickel foam substrate. Furthermore, the coating effect of the conductive layer further improves the chemical and mechanical stability of the material, effectively preventing the shedding of active materials and extending the electrode's service life. The preparation process of this invention is simple and the conditions are mild, making it suitable for large-scale industrial production.

[0091] (2) The multi-dimensional regulated metal-organic framework composite electrode provided by this invention exhibits synergistic effects among its layers, resulting in high conductivity, excellent electrocatalytic performance, and good stability. It has wide applications in electrocatalysis, energy storage, and environmental pollutant treatment. Attached Figure Description

[0092] Figure 1 This is a scanning electron microscope (SEM) image of a nickel foam substrate loaded with a metal-organic framework composite precursor, obtained after cleaning and drying the metal-organic framework composite precursor in step (1) of Embodiment 1 of the present invention.

[0093] Figure 2 This is a scanning electron microscope (SEM) image of a nickel foam substrate loaded with a metal-organic framework composite precursor, obtained after cleaning and drying the metal-organic framework composite precursor in step (1) of Comparative Example 1 of the present invention. Detailed Implementation

[0094] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0095] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0096] Unless otherwise specified, all reagents and consumables used in the following embodiments and comparative examples were purchased from conventional reagent manufacturers in the art. Table 1 lists the specific information of the raw materials used in the embodiments and comparative examples of the present invention, and Table 2 lists the specific information of the experimental equipment used in the embodiments and comparative examples of the present invention. Unless otherwise specified, the experimental methods and techniques used are conventional methods and techniques in the art.

[0097] Table 1

[0098]

[0099] Table 2

[0100]

[0101] Example 1

[0102] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode, the method comprising the following steps:

[0103] (I) Immerse the nickel foam substrate in acetone and ultrasonically clean it for 30 min; then immerse the nickel foam substrate in a 2 mol / L hydrochloric acid aqueous solution for 10 min; rinse with deionized water until neutral; and dry in an inert atmosphere at 70 °C for 1.5 h to obtain a clean nickel foam substrate.

[0104] (II) The foamed nickel substrate obtained in step (I) is placed in an electroplating solution. The foamed nickel substrate is used as the working electrode, the platinum mesh is used as the counter electrode, and the Ag / AgCl electrode is used as the reference electrode. Pulse electrochemical deposition is performed on the substrate to obtain a metal-organic framework composite precursor.

[0105] The electroplating solution comprises, by weight, 100 wt% nickel nitrate, 1.5 wt% cobalt nitrate, 0.3 wt% copper chloride, 1.5 wt% terephthalic acid, 2 wt% trimesic acid, 1 wt% furanyldicarboxylic acid, and 0.5% hexadecyltrimethylammonium bromide, with the remainder being DMF and water in a 1:1 mass ratio.

[0106] The voltage for pulsed electrochemical deposition was -1.6V, the temperature was 45℃, and the on / off time of pulsed electrochemical deposition was T. on / T off The ratio was 2:1, and the total time for pulsed electrochemical deposition was 90 min;

[0107] (III) The metal-organic framework composite precursor was sprayed and cleaned with N,N-dimethylformamide, ethanol and deionized water. The spraying pressure was 0.4 MPa and the cleaning time was 12 min each time. It was then dried at a vacuum of -0.098 MPa and 80°C for 10 h.

[0108] (IV) The dried metal-organic framework composite precursor was placed in a conductive filler dispersion and sonicated for 45 min to obtain a metal-organic framework composite precursor loaded with conductive filler.

[0109] Based on a total mass of 100wt% for the conductive filler dispersion, the conductive filler dispersion includes 10wt% carbon nanotube conductive filler, with the remainder being water;

[0110] (V) Under nitrogen protection, the metal-organic framework composite precursor loaded with conductive filler obtained in step (IV) is heated to 300°C for 4 hours at a heating rate of 3°C / min to obtain the multidimensional regulated metal-organic framework composite electrode.

[0111] The scanning electron microscope (SEM) image of the cleaned and dried nickel foam substrate loaded with the metal-organic framework composite precursor obtained after cleaning and drying the metal-organic framework composite precursor in step (Ⅲ) shows that the layer formed by the metal-organic framework composite precursor is a uniform film layer (the porous structure in the structure cannot be shown at this magnification).

[0112] Example 2

[0113] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the nickel nitrate content in the electroplating solution is 5%, the cobalt nitrate content is 2%, the deposition temperature is 30°C, the pulse voltage is -2.0V, and the deposition time is 150 min. The remaining steps are the same as in Example 1.

[0114] Example 3

[0115] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the electroplating solution contains 8% nickel nitrate, 1% cobalt nitrate, and 0.5% copper chloride; the deposition temperature is 60°C; the pulse voltage is -1.2V; and the deposition time is 30 min. The remaining steps are the same as in Example 1.

[0116] Example 4

[0117] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the electroplating solution contains 1% terephthalic acid, 2.5% trimesic acid, 0.5% furanyl dicarboxylic acid, and 0.1% sodium dodecylbenzenesulfonate as the surfactant. The remaining steps are the same as in Example 1.

[0118] Example 5

[0119] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the electroplating solution contains 2% terephthalic acid, 1% trimesic acid, 1.5% furanyl dicarboxylic acid, and 3% polyvinylpyrrolidone as the surfactant. The remaining steps are the same as in Example 1.

[0120] Example 6

[0121] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the conductive filler is 12% carbon black + 88% water (by weight), and the soaking time is 30 minutes. The remaining steps are the same as in Example 1.

[0122] Example 7

[0123] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the conductive filler is 8% graphene + 92% water (by weight), and the soaking time is 60 min. The remaining steps are the same as in Example 1.

[0124] Example 8

[0125] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the heat treatment temperature is 200℃, the heating rate is 2℃ / min, and the holding time is 5h. The remaining steps are the same as in Example 1.

[0126] Example 9

[0127] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the surfactant is a mixture of hexadecyltrimethylammonium bromide and polyvinylpyrrolidone (total content 0.5%) in a weight ratio of 1:2. The remaining steps are the same as in Example 1.

[0128] Example 10

[0129] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the conductive filler aqueous dispersion contains 6% carbon nanotubes, 6% graphene, and 88% mixed solvent (deionized water: ethanol = 1:1) by weight. The remaining steps are the same as in Example 1.

[0130] Example 11

[0131] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the electroplating solution solvent contains 45% DMF, 35% water, 15% ethanol, and 5% ethylene glycol (by weight). The remaining steps are the same as in Example 1.

[0132] Example 12

[0133] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The difference between this method and Example 1 lies only in the following: the surfactant is a mixture of hexadecyltrimethylammonium bromide and polyvinylpyrrolidone (total content 0.5%) in a weight ratio of 1:2; the conductive filler aqueous dispersion contains 6% carbon nanotubes, 6% graphene, and 88% mixed solvent (deionized water: ethanol = 1:1) by weight; the electroplating solution solvent contains 45% DMF, 35% water, 15% ethanol, and 5% ethylene glycol (by weight). The remaining steps are the same as in Example 1.

[0134] Example 13

[0135] This embodiment provides a method for preparing a multidimensionally regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that the voltage for pulsed electrochemical deposition is -2.5V, while the other steps are the same as those in Example 12.

[0136] Example 14

[0137] This embodiment provides a method for preparing a multidimensionally regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that the voltage for pulsed electrochemical deposition is -0.5V, while the remaining steps are the same as in Example 12.

[0138] Example 15

[0139] This embodiment provides a method for preparing a multi-dimensional regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that nickel nitrate is replaced with an equal mass of manganese nitrate, while the remaining steps are the same as in Example 12.

[0140] Example 16

[0141] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that cobalt nitrate is replaced with an equal mass of zinc nitrate, while the remaining steps are the same as in Example 12.

[0142] Example 17

[0143] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that the electroplating solution does not contain copper chloride. The remaining steps are the same as in Example 12.

[0144] Example 18

[0145] This embodiment provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and that of Example 12 is that the electroplating solution does not contain furanyl dicarboxylic acid. The remaining steps are the same as in Example 12.

[0146] Comparative Example 1

[0147] This comparative example provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that the on / off time ratio (Ton / Toff) of the pulsed electrochemical deposition is 5:1. The remaining steps are the same as in Example 1.

[0148] Figure 2The image shown is a scanning electron microscope (SEM) image of a nickel foam substrate loaded with a metal-organic framework composite precursor obtained after cleaning and drying the metal-organic framework composite precursor in step (III) of Comparative Example 1. The image shows that the layer formed by the metal-organic framework composite precursor has an irregular bulk structure.

[0149] Comparative Example 2

[0150] This comparative example provides a method for preparing a multi-dimensionally regulated metal-organic framework composite electrode. The only difference between this method and Example 1 is that step (IV) (conductive filler loading) is omitted, and the precursor dried in step (III) is directly subjected to subsequent heat treatment. The remaining steps are the same as in Example 1.

[0151] test:

[0152] (a) Conductivity test:

[0153] According to the national standard "Test Method for Conductivity of Electrode Materials for Lithium-ion Batteries" (SJ / T11792-2022), the conductivity of multi-dimensionally regulated metal-organic framework composite electrodes prepared in each of the following examples and comparative examples was measured using electrochemical impedance spectroscopy (EIS). Specifically, a 1 mol / L KOH electrolyte was prepared by mixing deionized water and analytical grade KOH, stirring until completely dissolved, and then allowing it to stand for degassing for 30 min. The composite electrode samples were cut into 1 cm × 1 cm pieces, ensuring that the electrode surface was free of damage and stains. Pretreated nickel foam (without a deposited MOF layer) was used as a blank control. An electrochemical workstation (CHI660E) and a three-electrode system were prepared (the working electrode was a composite electrode, the counter electrode was a platinum mesh, and the reference electrode was an Ag / AgCl electrode). The three electrodes were immersed in the KOH electrolyte with a fixed electrode spacing of 2 cm. The electrochemical workstation was connected to the three electrodes, and the initial parameters of the workstation (open-circuit potential monitoring) were set. The test was started after the open-circuit potential stabilized (fluctuation less than 5 mV / 10 min). The test frequency range was set to 0.01Hz-100kHz, with an amplitude of 5mV. The test was started, and the system automatically scanned from high to low frequencies, recording impedance data. Each sample was tested three times, and the average value was taken to reduce error. ZsimpWin software was used to fit the impedance data and extract the charge transfer resistance (Ro). ct ) value; according to R ct The magnitude determines the conductivity, R ct The smaller the value, the smaller the resistance to charge transfer at the electrode and the better the conductivity.

[0154] (II) Electrocatalytic activity test:

[0155] The electrocatalytic activity of the multidimensionally regulated metal-organic framework composite electrodes prepared in each of the following examples and comparative examples was measured according to the national standard "Test Method for Performance of Electrocatalysts for Oxygen Reduction Reaction" (GB / T39865-2021). Specifically, a 0.1 mol / L KOH electrolyte was prepared, and deionized water and analytical grade KOH were mixed and stirred until completely dissolved. High-purity oxygen (purity ≥99.99%) was bubbled through for 30 min until saturation, and oxygen was continuously bubbled through to maintain saturation during the test. The composite electrode sample was cut into 1 cm × 1 cm pieces. The counter electrode (platinum mesh) and the reference electrode (Ag / AgCl) were ultrasonically cleaned with ethanol and deionized water for 10 min respectively, and then dried. The three electrodes (working electrode: composite electrode; counter electrode: platinum mesh; reference electrode: Ag / AgCl) were inserted into the 0.1 mol / L KOH electrolyte saturated with O2, with the electrode spacing fixed at 1.5 cm to ensure complete immersion. The electrodes were connected to the test system, and the open-circuit potential was set for monitoring until the potential stabilized (fluctuation ≤3 mV / 5 min). Select the "Linear Scan Voltammetry" mode on the voltammeter, set the scan range to 0.2-1.0V (vsRHE) and the scan rate to 5mV / s; start the scan and record the current-potential curve in real time. Repeat the test three times for each sample, and collect the intermediate curve data. Extract the onset potential (Eonset, current density up to 0.1mA / cm²) from the LSV curve. 2 Corresponding potential), half-wave potential (E) 1 / 2 The potential corresponding to half of the limiting current density and the limiting diffusion current density (J) d The high-potential region stabilizes the current density, and the electrocatalytic activity is evaluated. The onset potential (E0) is used to assess this. onset ), half-wave potential (E) 1 / 2 The more positive the value, the higher the limiting diffusion current density (J). d The larger the value, the higher the electrocatalytic activity.

[0156] (III) Stability Testing:

[0157] The stability of the multidimensionally regulated metal-organic framework (MOF) composite electrodes prepared in each of the following examples and comparative examples was measured according to the national standard "Stability Test Method for Electrocatalytic Oxygen Reduction Catalysts" (GB / T39866-2021). Specifically, a 0.1 mol / L KOH electrolyte was prepared, stirred to dissolve, and then purged with high-purity nitrogen for 30 min to remove oxygen (to avoid O2 interference with CV testing). The composite electrode samples were cut into 1 cm × 1 cm pieces, and the surfaces were wiped with ethanol to remove impurities. The counter electrode (platinum mesh) and reference electrode (Ag / AgCl) were ultrasonically cleaned for 10 min and then dried. The initial surface morphology of the composite electrode was observed using SEM, and images of different regions (at least 3 locations) were taken. The distribution, particle state, and film integrity of the MOF composite layer and conductive layer were recorded as a benchmark for mechanical stability comparison. A cyclic three-electrode system was constructed by immersing the electrodes in deoxygenated KOH electrolyte and connecting them to a cyclic voltammeter (CV). Parameters were set as follows: scan range 0.2-1.0 V (vs RHE), scan rate 100 mV / s, and 10,000 cycles. The test was started, and the CV curves were recorded in real time. After the cycles, the electrocatalytic performance of the electrodes was tested using linear sweep voltammetry (LSV). The half-wave potential was extracted, and the shift from the initial half-wave potential (ΔE) was calculated. 1 / 2 The electrode surface morphology was observed again using SEM to compare the structural changes before and after cycling, and the ΔE was analyzed. 1 / 2 Electrode stability was assessed based on morphological differences.

[0158] The multidimensional regulated metal-organic framework composite electrodes prepared in the examples and comparative examples were tested, and the test results are shown in Tables 3 and 4 below.

[0159] Table 3

[0160]

[0161] Table 4

[0162]

[0163] The test results show that:

[0164] (1) As can be seen from Examples 1-12, this invention employs a pulsed electrochemical deposition process to promote the nucleation of metal ions on the substrate surface through electrochemical reduction, thereby enhancing the bonding force between the metal-organic framework composite layer and the nickel foam substrate. Furthermore, the coating effect of the conductive layer further improves the chemical and mechanical stability of the material, effectively preventing the shedding of active materials and extending the electrode's lifespan. Simultaneously, by synergistically optimizing factors such as the composition of the electroplating solution, pulsed electrochemical deposition parameters, conductive filler ratio, and solvent system, the structure of the metal-organic framework composite electrode can be controlled in multiple dimensions, resulting in a composite electrode with excellent conductivity, high electrocatalytic activity, and strong stability, thus meeting the application needs in fields such as electrocatalysis and energy storage. The preparation process of this invention is simple and the conditions are mild, making it suitable for large-scale industrial production.

[0165] (2) A comparison of Example 1 with Examples 13-14 shows that the present invention, by further controlling the voltage of pulsed electrochemical deposition to -2.0V to -1.2V, aims to promote the nucleation of metal ions on the surface of the nickel foam substrate through electrochemical reduction. If the voltage is too negative (below -2.0V), the metal ion reduction rate is too fast, which easily leads to amorphous deposition or precipitation of elemental metals, destroying the coordination structure of the MOF; if the voltage is too positive (above -1.2V), the reduction driving force is insufficient, the nucleation rate is slow, and it is difficult to form a continuous MOF composite layer. Excessive negative voltage leads to an excessively fast metal ion reduction rate, destroying the MOF coordination structure and resulting in amorphous deposition. Therefore, the charge transfer resistance (R) increases. ct The Ω value increased significantly to 8.5 Ω; the electrocatalytic activity decreased, and the onset potential (E) decreased. onset The voltage drops to 0.80V, and the half-wave potential (E) 1 / 2 As low as 0.65V, limiting diffusion current density (J d Only 4.1 mA / cm²; stability deteriorated, half-wave potential shift (ΔE) after 10,000 cycles. 1 / 2 The voltage reached 92mV, and the specific surface area decreased to 780m² / g due to structural damage. Excessive positive voltage resulted in insufficient reduction driving force, making it difficult to form a continuous MOF composite layer, leading to incomplete conductive pathways. ct The Ω value increased to 15.2 Ω; the electrocatalytic activity deteriorated, and E... onset 0.75V, E 1 / 2 0.60V, J d It has a strength of 3.5 mA / cm²; poor stability, ΔE 1 / 2 It reaches 125mV and has a specific surface area of ​​only 650m² / g.

[0166] (3) A comparison of Example 1 with Examples 15-16 shows that the present invention further selects nickel salt, cobalt salt, and copper salt as components of the electroplating solution to form a Ni-Co-Cu ternary metal ion system. In this system, the multiple metal ions (Ni, Co, Cu) synergistically interact with various organic ligands to form abundant active sites. Combined with the high specific surface area, this improves the electrocatalytic reaction rate and catalytic efficiency. Nickel ions are the main metal center of the MOF material, providing the basic coordination framework and electrocatalytic active sites. The introduction of cobalt ions can adjust the electronic structure of the MOF material and improve charge transfer efficiency. Copper ions, as an auxiliary active component, have a smaller ionic radius than nickel and cobalt ions and can partially replace nickel / cobalt ions in the crystal lattice, forming defect structures and increasing the number of active sites. However, Mn ions have poor coordination compatibility with the original organic ligands, R... ct The Ω value increased to 6.3 Ω; electrocatalytic performance decreased, E onset 0.86V, E 1 / 2 0.72V, J d It is 4.8 mA / cm²; stability is affected by coordination structure, ΔE 1 / 2 78mV, specific surface area 890m² / g; the electronic structure of Zn ions in Example 16 does not match that of Ni and Cu, disrupting the synergistic effect of the ternary metals, R ct The Ω value is 7.1 Ω; the electrocatalytic activity decreases, and E... onset 0.84V, E 1 / 2 0.70V, J d It is 4.6 mA / cm²; stability decreases, ΔE 1 / 2 It has a value of 85mV and a specific surface area of ​​820m² / g.

[0167] (4) As can be seen from Examples 1 and 17, when the electroplating solution does not contain copper chloride, the synergistic effect of Cu ions is lacking, the number of active sites decreases, and R... ct It is 4.8Ω, E 1 / 2 0.75V, ΔE 1 / 2 The voltage was 65mV, indicating a significant decrease in performance. This suggests that the synergistic effect of multiple metal ions is an important factor in improving electrode performance.

[0168] (5) As can be seen from Examples 1 and 18, when the electroplating solution does not contain furanyl dicarboxylic acid, the types of organic ligands are insufficient, resulting in a wide pore size distribution and a low specific surface area (920m²) in the MOF material. 2 / g), R ct It is 4.5Ω, E 1 / 2 0.74V, J d 4.8 mA / cm 2 The performance was inferior to that of Examples 1-12, demonstrating that the combination of multiple organic ligands can optimize the structure of MOF materials.

[0169] (6) As can be seen from Example 1 and Comparative Example 1, when the on / off time ratio T on / T off =5:1 exceeds the scope of this invention. SEM images show that the MOF composite precursor forms an irregular block structure with severe aggregation, leading to R ct Up to 5.6Ω, E 1 / 2 Only 0.72V, J d It is 4.5 mA / cm², ΔE 1 / 2 The voltage was 85mV, which is significantly worse than the example, demonstrating that the adjustment of pulse parameters is crucial to the material structure and performance.

[0170] (7) As can be seen from Example 1 and Comparative Example 2, when there is no conductive filler loading and the conductive layer is missing, R ct The resistance is as high as 12.3Ω, with extremely poor conductivity. After cycling, significant surface peeling occurs, and ΔE... 1 / 2 The voltage was 110mV, and the stability decreased significantly, demonstrating the important role of the conductive layer in improving the conductivity and stability of the electrode.

[0171] In summary, this invention employs a pulsed electrochemical deposition process to promote the nucleation of metal ions on the substrate surface through electrochemical reduction, enhancing the bonding force between the metal-organic framework composite layer and the nickel foam substrate. Furthermore, the coating effect of the conductive layer further improves the chemical and mechanical stability of the material, effectively preventing the shedding of active materials and extending the electrode's lifespan. Simultaneously, by synergistically optimizing factors such as the electroplating solution composition, pulsed electrochemical deposition parameters, conductive filler ratio, and solvent system, the structure of the metal-organic framework composite electrode can be controlled in multiple dimensions, resulting in a composite electrode with excellent conductivity, high electrocatalytic activity, and strong stability, thereby meeting the application requirements in fields such as electrocatalysis and energy storage. The preparation process of this invention is simple and the conditions are mild, making it suitable for large-scale industrial production.

[0172] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a multi-dimensional regulated metal organic framework composite electrode, characterized in that, The preparation method comprises the following steps: (1) placing a substrate in an electroplating solution to perform pulse electrochemical deposition on the substrate to obtain a metal organic framework composite precursor; (2) placing the metal organic framework composite precursor obtained in step (1) in a conductive filler dispersion liquid to obtain a metal organic framework composite precursor loaded with conductive fillers through ultrasonic treatment; (3) performing heat treatment on the metal organic framework composite precursor loaded with conductive fillers obtained in step (2) to obtain the multidimensional regulated metal organic framework composite electrode; The on / off time ratio T in step (1) of the pulsed electrochemical deposition on / T off The ratio is 1-3:1; The electroplating solution in step (1) comprises a metal salt, an organic ligand and a solvent.

2. The production method according to claim 1, characterized by, The substrate in step (1) is a nickel foam, a copper foam, a cobalt foam or a metal foil; Preferably, the substrate is used as a working electrode, a platinum mesh is used as a counter electrode and an Ag / AgCl electrode is used as a reference electrode in the process of pulse electrochemical deposition; Preferably, the voltage of pulse electrochemical deposition in step (1) is-2.0V to-1.2V; Preferably, the temperature of pulse electrochemical deposition in step (1) is 30-60℃; Preferably, the time of pulse electrochemical deposition is 30-100min.

3. The production method according to claim 1 or 2, characterized by, The metal salt comprises a nickel salt, a cobalt salt and a copper salt; Preferably, the organic ligand comprises terephthalic acid, trimesic acid and furan dicarboxylic acid; Preferably, the solvent comprises any one or a combination of at least two of N,N-dimethylformamide, water, ethanol or ethylene glycol; Preferably, the electroplating solution comprises 5wt%-8wt% of the nickel salt, 1wt%-2wt% of the cobalt salt, 0.2wt%-0.5wt% of the copper salt, 1wt%-2wt% of terephthalic acid, 1wt%-2.5wt% of trimesic acid, 0.5wt%-1.5wt% of furan dicarboxylic acid, 0.1wt%-3wt% of a surfactant and a solvent, based on the total mass of the electroplating solution as 100wt%; Preferably, the surfactant comprises any one or a combination of at least two of cetyltrimethylammonium bromide, polyvinylpyrrolidone or sodium dodecylbenzenesulfonate; Preferably, the surfactant comprises cetyltrimethylammonium bromide and polyvinylpyrrolidone at a mass ratio of 1:2-3; Preferably, the solvent comprises 40wt%-55wt% of N,N-dimethylformamide, 25wt%-40wt% of water, 12wt%-18wt% of ethanol and 5wt%-8wt% of ethylene glycol, based on the total mass of the solvent as 100wt%.

4. The production method according to any one of claims 1 to 3, characterized by, The conductive filler dispersion liquid comprises 8wt%-12wt% of conductive fillers and the balance is a first solvent, based on the total mass of the conductive filler dispersion liquid as 100wt%; Preferably, the conductive fillers comprise any one or a combination of at least two of carbon nanotubes, graphene or carbon black, preferably carbon nanotubes and graphene; Preferably, the first solvent comprises water and / or ethanol; Preferably, the conductive filler dispersion liquid comprises 3wt%-9wt% of carbon nanotubes, 4wt%-8wt% of graphene and the balance of the first solvent, based on 100wt% of the total mass of the conductive filler dispersion liquid, and the first solvent is water and ethanol in a weight ratio of 1-3:

1.

5. The production method according to any one of claims 1 to 4, characterized by, After step (1) and before step (2), the metal-organic framework composite precursor obtained in step (1) is further subjected to cleaning and drying; Preferably, the ultrasonic time in step (2) is 30min-60min.

6. The method of any one of claims 1-5, wherein, The temperature of the heat treatment in step (3) is 200℃-400℃; Preferably, the heat treatment time is 3h-5h; Preferably, the heating rate of the heat treatment is 2℃ / min-5℃ / min.

7. The method of any one of claims 1-6, wherein, The preparation method comprises the following steps: (I) Soak the foamed nickel substrate in acetone or ethanol, and ultrasonically clean for 20min-40min; then immerse the foamed nickel substrate in a 1mol / L-3mol / L hydrochloric acid or nitric acid aqueous solution for 5min-15min; rinse with deionized water until neutral; dry in an inert atmosphere at 60℃-80℃ for 1h-2h to obtain a clean foamed nickel substrate; (II) Place the foamed nickel substrate obtained in step (I) in an electroplating solution, take the foamed nickel substrate as a working electrode, take a platinum mesh as a counter electrode, and take an Ag / AgCl electrode as a reference electrode, and perform pulse electrochemical deposition on the substrate to obtain a metal-organic framework composite precursor; wherein, based on 100wt% of the total mass of the electroplating solution, the electroplating solution comprises 5wt%-8wt% of a nickel salt, 1wt%-2wt% of a cobalt salt, 0.2wt%-0.5wt% of a copper salt, 1wt%-2wt% of terephthalic acid, 1wt%-2.5wt% of trimesic acid, 0.5wt%-1.5wt% of furandicarboxylic acid, 0.1wt%-3wt% of a surfactant and a solvent; The surfactant comprises cetyltrimethylammonium bromide and polyvinylpyrrolidone in a mass ratio of 1:2-3; The solvent comprises 40wt%-55wt% of N,N-dimethylformamide, 25wt%-40wt% of water, 12wt%-18wt% of ethanol and 5wt%-8wt% of ethylene glycol, based on 100wt% of the total mass of the solvent; The voltage of the pulse electrochemical deposition is -2.0V to -1.2V, the on-off time ratio T of the pulse electrochemical deposition is 1-3:1, and the total time of the pulse electrochemical deposition is 30min-100min. on / T off 1-3:1, and the total time of the pulse electrochemical deposition is 30min-100min. (III) Spray clean the metal-organic framework composite precursor with N,N-dimethylformamide, ethanol and deionized water, the spraying pressure is 0.3MPa-0.45MPa, each cleaning time is 10min-15min, and then dry; (IV) Place the dried metal-organic framework composite precursor in a conductive filler dispersion liquid, and ultrasonically treat for 30min-60min to obtain a metal-organic framework composite precursor loaded with conductive fillers; The conductive filler dispersion liquid comprises 8wt%-12wt% of conductive fillers, based on 100wt% of the total mass of the conductive filler dispersion liquid, and the balance is a first solvent. (V) heating the metal-organic framework composite precursor loaded with the conductive filler obtained in step (IV) to 200-400°C at a temperature increase rate of 2°C / min-5°C / min for 3-5h under nitrogen protection to obtain the multi-dimensionally regulated metal-organic framework composite electrode.

8. A multi-dimensionally regulated metal-organic framework composite electrode, characterized in that, The multi-dimensionally regulated metal-organic framework composite electrode is prepared according to the preparation method of any one of claims 1-7.

9. The multi-dimensional regulated metal-organic framework composite electrode of claim 8, wherein, The multi-dimensionally regulated metal-organic framework composite electrode comprises a substrate, a metal-organic framework composite layer loaded on the surface of the substrate, and a conductive layer attached to the surface of the metal-organic framework composite layer. Preferably, the thickness of the substrate is 0.5-10mm. Preferably, the thickness of the metal-organic framework composite layer is 10-30μm. Preferably, the thickness of the conductive layer is 3-50nm. Preferably, the specific surface area of the multi-dimensional regulated metal organic framework composite electrode is 500 m 2 / g-3000 m 2 / g.

10. The use of the multi-dimensional regulated metal-organic framework composite electrode according to claim 1 or 2, characterized in that, The multi-dimensionally regulated metal-organic framework composite electrode is used in the field of electrocatalysis, energy storage or environmental pollutant treatment.

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