Ferronickel-based bimetallic organic framework catalyst and preparation method thereof

Abstract

The invention discloses a nickel-iron-based bimetallic organic framework catalyst and a preparation method thereof, and belongs to the field of electrochemical catalyst preparation, the preparation method comprises the following steps: step 1, dissolving a metal nickel salt in pure water, and carrying out ultrasonic dispersion to obtain a solution A; the preparation method comprises the following steps: dissolving a ferrocene dicarboxylic acid ligand in N, N-dimethylformamide to obtain a solution B; ultrasonically stirring and uniformly dispersing the solution A and the solution B to obtain a mixed solution; and 2, synthesizing the nickel-iron-based bimetallic organic framework catalyst from the mixed solution by using a hydrothermal method. The nickel-iron-based bimetal organic framework catalyst prepared by the preparation method disclosed by the invention shows good OER catalytic performance in an alkaline medium.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical catalyst preparation, and specifically relates to a nickel-iron-based bimetallic organic framework catalyst and a preparation method thereof. Background Art

[0002] Electrocatalysis, an emerging hydrogen production technology, has been rapidly developed in recent years due to its simplicity, high purity, and significant potential. The electrolysis of water to produce hydrogen essentially converts energy directly into chemical energy. If the electrolysis process matures, the resulting hydrogen storage material will not only be of higher purity but also directly achieve a higher hydrogen pressure. Furthermore, large-scale electrolysis of water to produce hydrogen using fossil fuels for electricity is more expensive than directly using fossil fuels. Furthermore, if hydrogen storage materials are manufactured using energy generated from non-renewable resources, greenhouse gas emissions are also higher than those from gas asset reforming. These high costs mean that electrocatalysis technology still lags behind traditional processes in terms of overall economic benefits and production capacity. Developing a catalyst with strong chemical stability and high catalytic efficiency can enhance the practical application of electrocatalysis. Improving energy conversion efficiency is key to enabling it to compete with traditional chemical processes.

[0003] Metal-organic frameworks (MOFs), due to their large surface area and tunable pores, can serve as primary diffusion pathways for macromolecular reactants and gases, acting as active reaction sites, thereby effectively enhancing catalytic activity. Previous research has confirmed their potential for development in catalytic technology. MOFs represent a novel organic-inorganic hybrid material, combining the advantages of both homogeneous and heterogeneous catalysts. Compared with traditional catalysts, MOFs exhibit large surface area, tunable pore size, and easily tunable structure and properties, favoring the anodic oxygen evolution reaction (OER) in water electrolysis. Currently reported bimetallic MOFs with high activity typically use conventional ligands such as carboxylic acids and nitrogen-containing azoles, with few reports on redox ligands. Ferrocene dicarboxylic acid inherently exhibits redox properties, and its iron center may influence metal nodes, thereby improving electrocatalytic activity. Two-dimensional NiFe-based bimetallic MOFs, with their unique layered structure and excellent safety, are considered one of the most promising OER electrocatalysts in alkaline environments. Based on the above considerations, the present invention will overcome the problem of reduced hydrogen production efficiency caused by sluggish kinetics of anode oxygen evolution reaction during the catalytic process of water electrolysis by regulating and optimizing electron transfer and reaction catalyst composition by controlling the metal node composition and morphology changes of MOF. Summary of the Invention

[0004] The present invention provides a nickel-iron-based bimetallic organic framework catalyst and a preparation method thereof. By regulating the metal node composition and morphology of the MOF, the electron transfer and catalytic structure are controlled and optimized to solve the problem of low efficiency of hydrogen production from water electrolysis caused by the slow kinetics of the anode oxygen evolution reaction in the water electrolysis catalytic process.

[0005] Technical solution: A method for preparing a nickel-iron-based bimetallic organic framework catalyst, comprising the following steps:

[0006] Step 1: dissolving a metal nickel salt in pure water and dispersing it ultrasonically to obtain a solution A; dissolving a ferrocene dicarboxylic acid ligand in N,N-dimethylformamide to obtain a solution B; and uniformly dispersing solution A and solution B by ultrasonic stirring to obtain a mixed solution;

[0007] Step 2: Use the hydrothermal method to synthesize the nickel-iron-based bimetallic organic framework catalyst using the mixed solution.

[0008] Preferably, in the mixed solution of step 1, the molar ratio of the metal nickel salt to the ferrocenedicarboxylic acid ligand is 2:8 to 6:4, and the volume ratio of N,N-dimethylformamide to pure water is 4:20 to 20:4. In the mixed solution, the concentration of the metal nickel salt is (0.008 to 0.025) mmol / mL.

[0009] Preferably, the metal nickel salt in the step is one of nickel chloride hexahydrate, nickel sulfate tetrahydrate, and nickel acetate tetrahydrate.

[0010] Preferably, in step 2, the conditions of the hydrothermal method are: temperature of 125° C.-145° C., and time of 3 h-15 h.

[0011] Preferably, the specific operation of step 2 is: injecting the mixed solution into the ligand solution contained in the polytetraethylene liner, placing the reactor, tightening the reactor cover, and heating under an oven; after the oven is naturally cooled, the upper clear liquid of the solution is poured out, and the lower layer material is drawn into a centrifuge tube for centrifugal treatment, followed by washing and drying with ethanol, and after washing, placing it in a 60°C oven under vacuum for 12 hours to obtain a nickel-iron-based bimetallic organic framework catalyst.

[0012] Preferably, in the mixed solution of step one, the metal nickel salt is nickel chloride hexahydrate, the molar ratio of the metal nickel salt to the ferrocene dicarboxylic acid ligand is 6:4, and the volume ratio of N,N-dimethylformamide to pure water is 20:4; the conditions of the hydrothermal method in step two are: the hydrothermal temperature is 145°C and the time is 3 hours.

[0013] Beneficial effect: The nickel-iron based bimetallic organic framework catalyst prepared by the present invention exhibits good OER catalytic performance in alkaline medium. The Fe / Ni-FcMO-DMF / H2O=20 / 4 (0.6 mmol of nickel chloride hexahydrate and 0.4 mmol of ferrocene dicarboxylic acid) prepared at a temperature of 145°C and a heating time of 3 h exhibits good OER catalytic performance at a current density of 10 mA / cm 2 After IR compensation, the overpotential reaches an astonishing 261.8mV. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 These are SEM characterization images of Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h in the examples.

[0015] Figure 2 These are the XRD patterns of Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h in the examples.

[0016] Figure 3 This is the TG / DTG curve of Fe / Ni-FcMOF at 145°C for 3 hours in the embodiment.

[0017] Figure 4 These are the IR characterization graphs of Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h in the examples.

[0018] Figure 5 These are the XPS curves of Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h in the examples.

[0019] Figure 6 CV curves of Fe / Ni-FcMOF-135℃-12h-X (X is different nickel salts) in 1.0M KOH solution in the examples.

[0020] Figure 7 The OER performance change trend diagram of Fe / NiFcMOF-X (X is metal salt doped in different proportions) in the embodiment; among them, a is doped with manganese sulfate, b is doped with manganese acetate, c is doped with cobalt chloride, and d is doped with cobalt nitrate.

[0021] Figure 8 CV curve of Fe / NiFcMOF-X (X is the ratio of nickel chloride hexahydrate to ferrocenedicarboxylic acid ligand) in the embodiment.

[0022] Figure 9: These are performance curves of the OER performance of Fe / Ni-FcMOF-X (X represents the conditions for the hydrothermal reaction) as a function of temperature and heating time in the examples; wherein, a is a CV curve of the OER performance of Fe / Ni-FcMOF-X (X represents the conditions for the hydrothermal reaction) as a function of hydrothermal temperature; b is a CV curve of the OER performance of Fe / Ni-FcMOF-X (X represents the conditions for the hydrothermal reaction) as a function of heating time.

[0023] Figure 10 CV curves showing the OER performance of Fe / Ni-FcMOF-X (X represents the volume ratio of DMF / H2O) in the example as the solvent changes. DETAILED DESCRIPTION

[0024] The technical solutions of the present invention are described in detail below through examples, but the protection scope of the present invention is not limited to the examples.

[0025] Example 1: Structural characterization of nickel-iron-based bimetallic organic framework catalysts.

[0026] 0.6 mmol of hexahydrate and nickel chloride were dissolved in 20 ml of water, and 0.4 mol of ferrocenedicarboxylic acid (also known as ferrocenedicarboxylic acid) was dissolved in 4 ml of DMF. The mixture was evenly dispersed and easily dispersed into a suspension. The resulting nickel-iron based bimetallic organic framework catalyst was incubated at 145°C for 3 h and was recorded as Fe / Ni-FcMOF-145°C-3h.

[0027] 0.6 mmol of nickel chloride was dissolved in 20 ml of water, and 0.4 mol of ferrocene was dissolved in 4 ml of DMF. The mixture was evenly dispersed and easily dispersed into a suspension. The nickel-iron-based bimetallic organic framework catalyst generated at 125°C for 12 h was recorded as Fe / Ni-FcMOF-125°C-12h.

[0028] 1) The results of Fe / Ni-FcMOF-145℃-3h were tested by scanning electron microscopy. Figure 1 As shown in a and b, the results of Fe / Ni-FcMOF-125℃-12h are as follows Figure 1 As shown in Figures c and d, the catalyst particles are composed of dense and uniform intersecting stacks of layered nanosheets. The nanosheets are approximately 4 μm wide and 200 nm thick, with a certain number of spherical nanoparticles attached to their surfaces. Their large longitudinal dimensions expose more active sites for the OER reaction. To a certain extent, the nanosheets act as current collectors, providing high-speed channels for electron transport. Electrons generated by the reaction are rapidly transferred across the nanosheets, accelerating the reaction and enhancing OER catalytic activity.

[0029] 2) XRD analysis:

[0030] Through XRD test, Cu Kα X-ray source The prepared materials and the corresponding calcined materials were analyzed by powder X-ray diffraction (PXRD) using a diffractometer model D / max-2200 / PC MPD. Figure 2 As shown, the XRD diffraction peaks of the layered nanosheet cluster catalyst material Fe / Ni-FcMOF-145℃-3h correspond exactly to the simulated XRD diffraction peaks of ferrocenedicarboxylic acid, indicating that the Ni doping does not change the structure of the original ligand. Furthermore, the XRD results of the comparative sample Fe / Ni-FcMOF-125℃-12h show that the XRD crystal structure does not change within a certain temperature and time range.

[0031] 3) TGA test and IR analysis:

[0032] The thermal stability of the prepared layered nanosheet cluster catalyst material Fe / Ni-FcMOF-145℃-3h was studied by thermogravimetric analysis (TGA). Figure 3 It can be seen that the temperature range from 400°C to 500°C is used to start and end the skeleton decomposition of the layered nanosheet cluster catalyst material Fe / Ni-FcMOF-145°C-3h. MOFs are prone to collapse at high temperatures. The high temperature that Fe / Ni-FcMOF-145°C-3h can withstand is 400°C, indicating that the nanosheet cluster catalyst material Fe / Ni-FcMOF-145°C-3h has good thermal stability. Thermogravimetric analysis results show that the reaction temperature of 145°C does not destroy the structure of the synthesized MOFs material.

[0033] In order to further analyze the component structure of the layered nanosheet cluster catalyst material Fe / Ni-FcMOF-145℃-3h, the characteristic absorption peak of the layered nanosheet cluster catalyst material Fe / Ni-FcMOF-145℃-3h was analyzed by infrared. Due to the different absorption of infrared radiation of different wavelengths by materials, the wavelength of 4000~500cm was used. -1 An infrared spectrometer was used to study the molecular structure and functional groups. First, grind an appropriate amount of potassium bromide under a heating lamp for later use. Then, a small amount of Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h were placed in a mortar, and potassium bromide (the ratio of catalyst to potassium bromide was 1:50) was weighed and ground and mixed. Then, the mixed MOFs catalyst and potassium bromide were pressed into a tablet test. The IR test results are shown in Figure 2. Figure 4 As shown in the figure, the measured samples Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h have the highest peaks at 1380cm -1There are absorption peaks at 818cm, which can be inferred to be the characteristic peak of the benzene ring, corresponding to the characteristic peak of the benzene ring of the organic ligand ferrocenedicarboxylic acid. -1 The peak at 1010cm -1 The peaks appearing at are those of Fe. The appearance of these peaks indicates that the ligand structure is not destroyed in the prepared material and still maintains its original composition.

[0034] 4) XPS characterization

[0035] In order to explore the elemental composition and electronic state of the layered nanosheet cluster catalyst materials Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h, X-ray photoelectron spectroscopy was performed on the catalysts Fe / Ni-FcMOF145℃-3h and Fe / Ni-FcMOF-125℃-12h. The results are as follows Figure 5 shown.

[0036] The previous characterization analysis of the catalyst materials Fe / Ni-FcMOF-145℃-3h and Fe / Ni-FcMOF-125℃-12h showed only that the crystal structure and functional groups were consistent, and the structure and composition did not change. Figure 5 The XPS structures show that they are different. From the elemental analysis of O1s and Ni 2p, it can be seen that Fe / Ni-FcMOF-145℃-3h has a negative shift compared with Fe / Ni-FcMOF-125℃-12h, indicating that the introduction of secondary metals can change the electronic structure of the original ligands. The change in charge density means that there is a significant electronic interaction between Ni and Fe, which is conducive to charge transfer and thus promotes the electrochemical process.

[0037] Example 2: Electrocatalytic OER Test of NiFe-based Bimetallic Organic Framework Catalysts Prepared under Different Conditions

[0038] This test experiment uses an electrochemical test workstation, uses a 1M KOH saturated solution as the electrolyte at room temperature, and uses a three-electrode system for testing. The three electrodes in the three-electrode system include a reference electrode of saturated silver chloride and a saturated calomel electrode, a counter electrode of platinum wire electrode, and a working electrode of glassy carbon electrode (0.1962 cm 2), with an inner diameter of 5 mm. Using an electronic balance, 2.5 mg of the prepared nickel-iron bimetallic organic framework catalyst and 2.5 mg of conductive carbon black were weighed into a centrifuge tube. 900 μL of isoethanol solution was added as a solvent for ultrasonic dispersion. Subsequently, 50 μL of Nafion was added to prevent particle shedding and reduce interference from other substances by electrostatic interaction. Using a pipette, the evenly dispersed suspension was pipetted onto a platinum carbon electrode. After drying at room temperature, the process was repeated four times, with 10 μL of the suspension applied to the platinum carbon electrode to form a uniform film, ultimately yielding a catalyst-loaded working electrode. Cyclic voltammetry (CV) was used to test the anodic oxygen evolution reaction (OER) performance of water electrolysis. The overpotential is used to measure the activity of the electrocatalyst. The lower the overpotential, the lower the actual voltage at a specified current density, indicating lower energy consumption and higher catalytic performance. The theoretical voltage for hydrogen production from water electrolysis is fixed at 1.23 V, and the actual voltage can be determined through test results. The scanning voltage of this experiment was 0-0.8V, and the scanning rate was 5mV / s.

[0039] 1) Nickel-iron-based bimetallic organic framework catalysts were prepared using different nickel salts and subjected to electrocatalytic OER tests.

[0040] First, 0.5 mmol of different metal salts (nickel chloride hexahydrate, nickel sulfate tetrahydrate, nickel acetate tetrahydrate) and ferrocenedicarboxylic acid were weighed and dissolved in 12 ml of deionized water and 12 ml of DMF, respectively. The obtained nickel-iron-based bimetallic organic framework catalyst was heated at 135°C for 12 h and recorded as Fe / Ni-FcMOF-135°C-12h-X (X is different nickel salts).

[0041] The electrocatalytic OER test results are as follows Figure 6 As shown, from Figure 6 It can be seen that when the nickel salt is nickel chloride, the current density under the electrochemical reaction is 10mA / cm 2 The overpotential is the lowest when , which is only 289mV, indicating that the activity of the prepared NiCl2 as metal salt is higher.

[0042] 2) Prepare nickel-iron-based bimetallic organic framework catalysts introducing other metal salts and conduct electrocatalytic OER tests.

[0043] The electrocatalytic OER test results are as follows Figure 7As shown in the figure, the OER performance of the NiFe-based bimetallic organic framework (BOF) catalyst after the introduction of Mn and Co salts is inferior to that of the NiFe-based BOM-based OEF catalyst prepared without the addition of other elements. This indicates that the OER catalytic performance of the pure Ni / Fe bimetallic is generally stronger than that of the catalyst doped with other metal salts, presumably due to the strong synergistic effect between the Ni / Fe bimetallics. NiFe layered double hydroxides (LDHs) have a unique layered structure and excellent stability. The introduction of other metal salts may have destroyed the layered structure of this LDH to some extent.

[0044] 3) Prepare nickel-iron-based bimetallic organic framework catalysts with different ratios of metal salt to ligand and conduct electrocatalytic OER tests.

[0045] Nickel chloride hexahydrate was dissolved in 12 ml of pure water, and ferrocenedicarboxylic acid was dissolved in 12 ml of N,N-dimethylformamide. After mixing, a hydrothermal reaction was carried out at a temperature of 135°C and a heating time of 12 h to obtain a nickel-iron-based bimetallic organic framework catalyst Fe / Ni-FcMOF-X (X represents the ratio of Ni / Fe).

[0046] The amounts of nickel chloride hexahydrate and ferrocenedicarboxylic acid were set to 0.2 mmol and 0.8 mmol, 0.4 mmol and 0.6 mmol, 0.5 mmol and 0.5 mmol, 0.6 mmol and 0.4 mmol, and 0.8 mmol and 0.2 mmol, respectively.

[0047] The performance of the electrocatalysts prepared with different ratios of metal salt to ligand in the oxygen evolution reaction at the anode of water electrolysis in 1.0 M KOH electrolyte was determined. The results are as follows Figure 8 As shown,

[0048] from Figure 8 It can be seen that the current density is 10 mA / cm when Ni / Fe=6 / 4 in Fe / Ni-FcMOF-X. 2 The overpotential is the lowest, reaching 287.8mV. The figure shows that within a certain range, the higher the proportion of ferrocenedicarboxylic acid ligands, the stronger the OER catalytic activity of the prepared electrocatalyst. When the proportion of ferrocenedicarboxylic acid ligands exceeds 40%, the addition of more Ni salts not only does not improve the performance, but also shows a downward trend. It can be inferred that its excellent OER performance is due to the ferrocenes as effective electron transfer intermediates. Properly increasing the amount of ferrocenes can improve the efficiency of electron transfer.

[0049] 4) The temperature and time of the hydrothermal reaction were changed to prepare nickel-iron-based bimetallic organic framework catalysts and perform electrocatalytic OER tests.

[0050] 0.6 mmol of nickel chloride hexahydrate was dissolved in 12 ml of pure water, and 0.4 mmol of ferrocenedicarboxylic acid was dissolved in 12 ml of N,N-dimethylformamide. After mixing, a hydrothermal reaction was carried out at a temperature of 105°C-155°C and a heating time of 3h-12h to obtain a nickel-iron-based bimetallic organic framework catalyst Fe / Ni-FcMOF-X (X represents the conditions of the hydrothermal reaction).

[0051] The electrocatalytic OER test results are as follows Figure 9 As shown by Figure 9 In a, it can be seen that the curve reaches 10mA / cm fastest when the heating temperature is 145℃. 2 , Figure 9 Figure b shows that the best performance was achieved when heated at 145°C for 3 hours. Increasing the heating time significantly decreased the CV curve. The optimal heating temperature is 145°C. Temperatures too low will incomplete the reaction, while temperatures too high will partially destroy the Fe / Ni-FcMOF-X structure. The optimal heating time is 3 hours; longer heating times can also damage the catalyst nanosheet structure.

[0052] 5) The ratio of pure water and ferrocenedicarboxylic acid was changed to prepare nickel-iron-based bimetallic organic framework catalysts and conduct electrocatalytic OER tests.

[0053] 0.6 mmol nickel chloride hexahydrate was dissolved in (1-20) mL pure water, and 0.4 mmol ferrocenedicarboxylic acid was dissolved in (4-23) mL N,N-dimethylformamide. The mixture was then subjected to a hydrothermal reaction at 145°C for 3 h to obtain a nickel-iron-based bimetallic organic framework catalyst Fe / Ni-FcMOF-X (X represents the volume ratio of DMF / H2O).

[0054] The electrocatalytic OER test results are as follows Figure 10 As shown, when the amount of DMF was changed to 4, 8, 12, 16, and 20, it was found that the performance improved with the increase of DMF amount. Subsequently, DMF = 22, 23, and 24 ml were added to the experiment. When the solvent was pure DMF, no separated product was found during centrifugation. Figure 10 The CV curves show that optimal performance is achieved when the DMF and water concentrations are 20ml and 4ml, respectively. The synthesized material is unstable when pure DMF is used as the solvent. Analysis suggests that water participates in the synthesis of Fe / NiMOF-X to some extent, but excessive water has a certain inhibitory effect on the synthesis of the catalyst.

[0055] The present invention synthesizes a nickel-based OER catalyst with ferrocene dicarboxylic acid as a ligand by a hydrothermal method. First, an attempt is made to change the type of nickel salt to obtain a Fe / Ni-FcMO-X (X is a conditional variable) electrochemical catalyst that is easier to generate and has better performance. Subsequently, the structure and morphology of the OER catalyst are controlled by introducing defects by doping other metals, controlling the temperature of the hydrothermal reaction, and the solvent system, so that its specific surface area is increased, resulting in its catalytic active sites being fully exposed. The material structure, element valence, composition, and morphology are analyzed by means of XRD, SEM, TEM, XPS, etc. With the purpose of improving the OER catalytic performance of the catalyst, the corresponding path is designed to prepare the electrocatalyst and study its electrocatalytic mechanism, and the following conclusions are drawn:

[0056] 1. Thermogravimetric analysis revealed that Fe / Ni-FcMOF-X exhibited excellent thermal stability. Furthermore, infrared analysis, XRD patterns, and SEM spectra revealed that the hydrothermal reaction of ferrocenedicarboxylic acid and nickel chloride resulted in the synthesis of ideal two-dimensional MOF nanosheets.

[0057] 2. Fe / Ni-FcMO-DMF / H2O=20 / 4 (0.6 mmol of nickel chloride hexahydrate and 0.4 mmol of ferrocene dicarboxylic acid) prepared by a hydrothermal method with a simple process and few operating steps at 145°C for 3 h showed excellent OER performance in electrochemical tests with a current density of 10 mA / cm 2 The overpotential after IR compensation reached an astonishing 261.8 mV, indicating that the Fe / NiMOF-X synthesized by the hydrothermal method has good catalytic activity and kinetics, which means it has a good practical application background.

[0058] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing a nickel-iron-based bimetallic organic framework catalyst, characterized in that: Step 1: dissolving a metal nickel salt in pure water and dispersing it ultrasonically to obtain a solution A; dissolving a ferrocene dicarboxylic acid ligand in N,N-dimethylformamide to obtain a solution B; and uniformly dispersing solution A and solution B by ultrasonic stirring to obtain a mixed solution; Step 2: Use the hydrothermal method to synthesize the nickel-iron-based bimetallic organic framework catalyst using the mixed solution.

2. The preparation method according to claim 1, characterized in that In the mixed solution of step 1, the molar ratio of the metal nickel salt to the ferrocenedicarboxylic acid ligand is 2:8 to 6:4; the volume ratio of N,N-dimethylformamide to pure water is 4:20 to 20:4; and the concentration of the metal nickel salt in the mixed solution is (0.008 to 0.025) mmol / mL.

3. The preparation method according to claim 1, characterized in that The metal nickel salt is one of nickel chloride hexahydrate, nickel sulfate tetrahydrate and nickel acetate tetrahydrate.

4. The preparation method according to claim 1, characterized in that In step 2, the conditions of the hydrothermal method are: temperature of 125° C.-145° C., and time of 3 h-15 h.

5. The preparation method according to claim 4, characterized in that The specific operations of step 2 are: The mixed solution was injected into the ligand solution in the polytetraethylene liner, placed in the reactor, the lid was tightened, and the reactor was heated in an oven at a temperature of 125°C-145°C for 3h-15h. After the oven is cooled naturally, the upper clear liquid of the solution is poured out, and the lower layer material is drawn into a centrifuge tube for centrifugal treatment, followed by washing and drying with ethanol. After washing, it is placed in a 60°C oven under vacuum and dried for 12 hours to obtain a nickel-iron-based bimetallic organic framework catalyst.

6. The preparation method according to claim 1, characterized in that In the mixed solution of step 1, the metal nickel salt is nickel chloride hexahydrate, the molar ratio of the metal nickel salt to the ferrocenedicarboxylic acid ligand is 6:4, and the volume ratio of N,N-dimethylformamide to pure water is 20:4; The conditions of the hydrothermal method in step 2 are: hydrothermal temperature is 145° C., and time is 3 hours.

7. A nickel-iron based bimetallic organic framework catalyst prepared by the preparation method according to claim 1.

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