Preparation method and application of two-dimensional covalent organic framework material with nickel-iron composite nanotube network morphology
By synthesizing and modifying two-dimensional covalent organic framework materials through a solvothermal method, a nickel-iron composite nanotube network morphology material was prepared, which solved the problem of slow kinetics of the four-electron oxygen evolution reaction at the anode and achieved low overpotential catalysis of oxygen. Precipitation reaction, excellent performance and low cost.
Patent Information
- Application Number
- CN202411308952.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-01-21
AI Technical Summary
In the prior art, the kinetic process of the anode four-electron oxygen evolution reaction is slow, resulting in an overpotential too high, limiting the randomness, uncertainty and spatiotemporal distribution of renewable energy as inputs of electrolytic water in electrolytic water.
A high-crystalline two-dimensional covalent organic framework material (COF) was synthesized using a solvothermal method, and modified on the COF through liquid-phase chemical synthesis to obtain a nickel-iron composite nanotube network morphology material, which can be used as an efficient oxygen evolution reaction electrode. .
It achieves catalytic oxygen evolution reaction at lower overpotential. The material has precise structure, strong periodicity, excellent performance and low cost. It can replace precious metal catalysts and meet the needs of environmentally friendly production.
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Figure CN119332298A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of porous material electrocatalyst preparation, and specifically relates to the preparation of an oxygen evolution catalyst. The method first synthesizes a high-crystalline COF by a solvent thermal method, and then performs liquid phase chemical synthesis and post-modification on the COF to obtain a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology. Background Art
[0002] Hydrogen has the advantages of high energy density, good energy conversion effect, and clean combustion products. It is considered to be one of the most promising alternatives to fossil fuels. Using renewable energy such as solar energy, wind energy, and tidal energy to produce hydrogen through water electrolysis is an environmentally friendly way to produce hydrogen with broad development prospects. The current bottleneck of water electrolysis is mainly concentrated on the slow kinetics of the four-electron oxygen evolution reaction at the anode. Excessive overpotential limits the randomness, uncertainty, and spatiotemporal distribution of renewable energy as energy input for water electrolysis. Therefore, in the prior art, a material with precise structure, strong periodicity, and low overpotential is needed. On the one hand, it can be used as an efficient oxygen evolution reaction electrode for practical production applications. On the other hand, it can be used as a theoretical chemistry research model to further reveal the four-electron transfer process of the anode reaction. Summary of the invention
[0003] Based on the above analysis, the present invention provides a method for preparing a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology, and utilizes its precise chemical structure to effectively realize the catalytic oxygen evolution reaction at a lower overpotential.
[0004] In order to achieve the above object, the present invention adopts the following technical solution: A method for preparing a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology comprises the following steps: (1) A certain amount of tri(4-aminophenyl)amine and 2,2'-bipyridine-5,5'-dicarboxaldehyde were ground and mixed in a mortar and transferred to a glass test tube. A poor solvent, a catalyst, and a good solvent were added in sequence. The system was then frozen with liquid nitrogen, evacuated, flame-sealed, and transferred to an oven at a certain temperature and allowed to stand for a period of time. The solid was then taken out for Soxhlet extraction and vacuum tube drying to obtain a high-crystalline COF.
[0005] (2) Grinding the COF obtained in step (1) and dispersing it in a mixed solution of ethanol and water containing ferric acetate and nickel acetate, ultrasonicating and stirring for a period of time, centrifuging the obtained solution, washing, and repeating this process several times until the supernatant is almost colorless, and drying it in a vacuum oven overnight to obtain a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology.
[0006] Furthermore, the poor solvent in step (1) is preferably 1,3,5-trimethylbenzene, or o-dichlorobenzene.
[0007] Furthermore, the catalyst in step (1) is an acetic acid aqueous solution after oxygen-free treatment, with a concentration of 2-6 mol / L and an addition amount of 0.1-0.5 mL.
[0008] Furthermore, the good solvent in step (1) is preferably 1,4-dioxane, or may be methanol or ethanol.
[0009] Furthermore, the glass tube described in step (1) has an inner diameter of 8 mm, an outer diameter of 10 mm, and a length of 15-20 cm.
[0010] Furthermore, in step (1), the oven temperature is 80-120° C., and the standing time is 3 to 7 days.
[0011] Furthermore, the solvent used for Soxhlet extraction in step (1) is a mixture of acetone, tetrahydrofuran and n-hexane.
[0012] Furthermore, in the mixed solution of ethanol and water containing ferric acetate and nickel acetate in step (2), the content of ferric acetate is 1-10 mg / mL, the content of nickel acetate is 1-10 mg / mL, and the volume ratio of ethanol to water is 1:(0.1-10).
[0013] Furthermore, the ultrasonic time in step (2) is 10-60 min.
[0014] Furthermore, the stirring time in step (2) is 8-24 hours.
[0015] Furthermore, the centrifugal speed in step (2) is 4000-10000 rpm, and the duration is 1-10 min.
[0016] Application: The two-dimensional covalent organic framework material with the nickel-iron composite nanotube network morphology is used as a catalyst in the catalytic oxygen evolution reaction of water electrolysis.
[0017] The advantages of the present invention are: The present invention develops a method for preparing a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology. The synthesis of the COF material and the loading of the active center are achieved through a one-step solvent thermal and one-step liquid phase chemical synthesis. The obtained material has a precise structure, good periodicity and excellent performance. Compared with the prior art, the method utilizes the weakly acidic environment of the metal salt in the post-treatment process to create a unique nanotube cross-network morphology, and its ordered mesoporous structure improves the mass transfer effect of the reactants. At the same time, the two-dimensional conjugated network structure increases the conduction capacity of the electrons and promotes the conversion of the reaction intermediates on the catalyst surface. In addition, the synthetic raw materials of the material are low in cost and high in abundance in nature. The catalyst material prepared by the method has better catalytic oxygen evolution reaction performance than commercial precious metal materials, and is expected to achieve the use of non-precious metals to replace precious metal catalytic materials, which is more in line with environmentally friendly production needs. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The drawings of this specification are used together with the above-mentioned invention content to further illustrate the technical concept of the present invention. The present invention should not be interpreted as being limited to the contents described in the drawings.
[0019] Figure 1 These are the experimental data and simulation data of the X-ray diffraction spectrum of the COF material prepared in step (1) of Example 1.
[0020] Figure 2 This is a spherical aberration corrected transmission electron micrograph of the two-dimensional covalent organic framework material of the nickel-iron composite nanotube network morphology prepared in step (2) of Example 1.
[0021] Figure 3 This is the X-ray photoelectron spectrum of the material prepared in step (2) of Example 1.
[0022] Figure 4 The linear voltammetric curves of the electrocatalytic oxygen evolution reaction of Example 1, commercial ruthenium dioxide, Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION
[0023] Hereinafter, the present invention will be described in detail with reference to embodiments to specifically describe the present invention. However, embodiments of the present invention may be modified into various other forms and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.
[0024] The experimental methods in the following examples, unless otherwise specified, are generally conventional conditions in the art or conditions recommended by the manufacturer; the raw materials and equipment used are all commercially available from conventional markets, etc., unless otherwise specified.
[0025] Example 1 Step (1) Synthesis of high-crystalline two-dimensional covalent organic framework materials: 11.6 mg of tris(4-aminophenyl)amine and 12.7 mg of 2,2'-bipyridine-5,5'-dicarboxaldehyde were ground in a mortar for 10 min and mixed evenly. The obtained powder sample was added to a glass test tube with a length of 25 cm, an inner diameter of 8 mm, and an outer diameter of 10 mm, compacted with a glass rod, and 1.2 mL of ultra-dry 1,3,5-trimethylbenzene, 0.2 mL of 4 mol / L anaerobic acetic acid solution, and 0.8 mL of ultra-dry 1,4-dioxane were added in sequence. The bottom 4 cm of the glass test tube containing the solution was immersed in liquid nitrogen and cooled with liquid nitrogen for 3 minutes until the solvent was completely solidified. The glass test tube was taken out, and the test tube opening, transfer valve and vacuum oil pump were connected together through a rubber tube. The transfer valve and the oil pump were opened to evacuate for 1 minute, and the transfer valve was closed to keep the inside of the glass test tube in vacuum. The butane gun flame was used to seal. The length of the sealed glass test tube was shortened from 25 cm to 15 cm, and the inner and outer diameters remained unchanged. The flame-sealed glass test tube was inserted into a beaker filled with quartz sand to ensure that the liquid surface was completely immersed in the quartz sand. It was transferred to an 80°C oven and taken out after standing for four days. The red solid was Soxhlet extracted with a mixed solution of acetone:tetrahydrofuran:n-hexane in a volume ratio of 8:1:1 for 3 days, and vacuum dried at 50°C for 12 hours to obtain a high-crystalline two-dimensional covalent organic framework material (COF).
[0026] Step (2) Introduction and compounding of nickel-iron metal active centers: A certain amount of iron acetate and nickel acetate were ultrasonically dissolved in a solution of ethanol and water in a volume ratio of 1:1, so that the mass concentration of both reached 2 mg / mL. 20 mg of the COF obtained in step (1) was ground in a mortar for 5 minutes to uniformly disperse the aggregated COF particles into powder, and then added to 20 mL of the above solution, ultrasonicated for 30 minutes, and stirred for 8 hours to allow the iron ions and nickel ions to uniformly enter the COF pores. Then, the solid and liquid were separated by centrifugation at a speed of 8000 rpm for 5 minutes, and the supernatant was discarded. The lower layer of solid was centrifuged and washed twice with water and ethanol using the same centrifugation parameters, and finally dried in vacuum at 50°C for 12 hours to obtain a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology.
[0027] Figure 1 The experimental data and simulation data of the X-ray diffraction spectrum of the COF material prepared in Example 1 show that the synthesized COF material is consistent with the results of theoretical simulation, and specific crystallographic parameters are obtained. Figure 2This is a spherical aberration-corrected transmission electron micrograph of the two-dimensional covalent organic framework material of the nickel-iron composite nanotube network morphology prepared in Example 1. It can be seen that at the microscopic scale, the morphology of the material is a cross-network morphology composed of nanotubes, and its mesoporous structure improves the mass transfer effect of the reactants, and its two-dimensional conjugated network structure increases the conductivity of electrons and promotes the conversion of reaction intermediates on the catalyst surface. Figure 3 This is the X-ray photoelectron spectrum of the material prepared in Example 1. It can be seen that the iron and nickel elements in the material are both in the form of positive ions, and the atomic fractions of iron and nickel contained in the material are 2.35 at.% and 2.27 at.%, respectively.
[0028] Comparative Example 1 The product was obtained by repeating steps (1) to (2) of Example 1, except that nickel acetate was not added in step (2).
[0029] Comparative Example 2 The product was obtained by repeating steps (1) to (2) of Example 1, except that no ferric acetate was added in step (2).
[0030] Figure 4 The linear voltammetric curves of the electrocatalytic oxygen evolution reaction of Example 1, commercial ruthenium dioxide, Comparative Example 1 and Comparative Example 2, wherein the conductive agent Ketjen black was added when the catalyst ink was prepared in Example 1, Comparative Example 1 and Comparative Example 2 (the mass ratio of active substance to Ketjen black was 4 to 1). Adding a conductive agent is a conventional method used to improve the conductivity of COF when testing materials in this field. The added conductive agent Ketjen black is mainly composed of carbon and is only used to improve the conductivity. It has no effect on the catalytic activity. Ruthenium dioxide, as a metal oxide, has excellent conductivity and does not require additional conductive agents. The two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology prepared in Example 1 has a current density of 50 mA / cm 2 The overpotential is only 308 mV, which has a lower oxygen evolution overpotential than commercial precious metal materials ruthenium dioxide (345 mV), Comparative Example 1 (398 mV), and Comparative Example 2 (419 mV), proving that it has great application potential as a non-precious metal COF-derived catalyst.
[0031] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.
Claims
1. A method for preparing a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology, characterized in that: The following steps are involved: (1) A certain amount of tris(4-aminophenyl)amine and 2,2'-bipyridine-5,5'-dicarboxaldehyde were ground and mixed in a mortar, and then transferred to a glass test tube. A poor solvent, a catalyst, and a good solvent were added in sequence. The system was then frozen with liquid nitrogen, evacuated, flame-sealed, and transferred to an oven at a certain temperature and allowed to stand for a period of time. The solid was then taken out for Soxhlet extraction and vacuum drying to obtain high-crystalline COF; (2) The COF obtained in step (1) is ground and dispersed in a mixed solution of ethanol and water containing ferric acetate and nickel acetate, and ultrasonicated and stirred for a period of time. The obtained solution is centrifuged and washed until the supernatant is colorless, and dried in a vacuum oven overnight to obtain a two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology.
2. The preparation method according to claim 1, characterized in that: The poor solvent described in step (1) is 1,3,5-trimethylbenzene or o-dichlorobenzene.
3. The preparation method according to claim 1, characterized in that: The catalyst in step (1) is an acetic acid aqueous solution after oxygen-free treatment, with a concentration of 2-6 mol / L.
4. The preparation method according to claim 1, characterized in that: The good solvent described in step (1) is one of 1,4-dioxane, methanol and ethanol.
5. The preparation method according to claim 1, characterized in that: In step (1), the oven temperature is 80-120° C. and the standing time is 3 to 7 days.
6. The preparation method according to claim 1, characterized in that: The solvent used for Soxhlet extraction in step (1) is a mixture of acetone, tetrahydrofuran and n-hexane.
7. The preparation method according to claim 1, characterized in that: In the mixed solution of ethanol and water containing ferric acetate and nickel acetate described in step (2), the content of ferric acetate is 1-10 mg / mL, the content of nickel acetate is 1-10 mg / mL, and the volume ratio of ethanol to water is 1:(0.1-10).
8. The preparation method according to claim 1, characterized in that: In step (2), the ultrasonication time is 10-60 min; and the stirring time is 8-24 h.
9. A two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology obtained according to the preparation method according to any one of claims 1 to 8.
10. Use of the two-dimensional covalent organic framework material with a nickel-iron composite nanotube network morphology according to claim 9 as a catalyst in the catalytic oxygen evolution reaction of water electrolysis.