Preparation method of magnetic NiFe2O4-coated FeNi (OH) x electrocatalyst with core-shell structure
By preparing the core-shell structure magnetic NiFe2O4@FeNi(OH)x electrocatalyst, the problem of insufficient OER performance of NiFe-LDH is solved, and efficient and low-cost electrolytic hydrogen production is achieved, which is suitable for the field of electrolytic hydrogen production.
Patent Information
- Application Number
- CN202510239719.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-07-04
AI Technical Summary
Existing cheap transition metal-based electrocatalysts such as NiFe-LDH are insufficient in electrolytic oxygen evolution reaction (OER), and existing regulatory strategies increase the cost of electrolytic hydrogen production and device complexity.
The core-shell structure magnetic NiFe2O4@FeNi(OH)x electrocatalyst was prepared by hydrothermal and heat treatment methods, forming a multi-stage structure and large specific surface area, exposing the active sites, and using magnetic NiFe2O4 cores to regulate the FeNi(OH)x shell spin state.
It improves the alkaline electrocatalytic oxygen evolution performance of the electrocatalyst, reduces production costs, and is suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] The present invention belongs to a preparation method of an electrocatalyst, specifically a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst preparation method. Background Art
[0002] Hydrogen energy is an ideal alternative energy source, which has the advantages of high energy density, clean and pollution-free, renewable, and wide application range. Therefore, the development and utilization technologies of hydrogen energy have received widespread attention from countries around the world. However, feasible large-scale hydrogen production technologies have restricted the development of the hydrogen economy. Currently, traditional fossil energy-based hydrogen production technologies are energy-intensive and greenhouse gas CO2 emission-intensive processes, while the technology of using renewable energy to drive water electrolysis to produce green hydrogen is a clean, efficient, and sustainable hydrogen production method. However, currently, noble metals Pt and IrO2 or RuO2 are the most efficient catalysts for hydrogen evolution and oxygen evolution in water electrolysis respectively. However, due to their low reserves and high prices, they have restricted the large-scale application of water electrolysis for hydrogen production. Therefore, designing and developing cheap, efficient, and stable electrocatalysts is the key to accelerating the development of the hydrogen economy.
[0003] The water electrolysis process consists of two half-electrode reactions: hydrogen evolution reaction (HER) at the cathode and oxygen evolution reaction (OER) at the anode. Among them, the OER process involves 4 electron transfers and is kinetically slow. Therefore, the OER process is considered to be the determining step for the efficiency of electrochemical water decomposition. Currently, cheap transition metal-based electrocatalysts, especially NiFe-LDH, are considered to be a promising OER electrocatalyst. However, its performance still cannot meet the requirements of industrial production. To improve the OER activity of this material, methods of increasing the number of active sites and regulating the electronic structure are currently widely used to modify NiFe-based catalysts. However, these strategies do not take into account that the NiFe-LDH material is an antiferromagnetic material with highly tunable electronic orbitals, providing a structural basis for adjusting the spin state of the catalyst. Current strategies for regulating the spin of NiFe-LDH mainly focus on two methods: doping with transition metal heteroatoms and constructing magnetic heterointerfaces. However, both of these strategies require the application of an external magnetic field, which increases the cost of water electrolysis for hydrogen production and complicates the electrolysis device. For the above reasons, the present invention proposes a core-shell structured catalyst with a magnetic NiFe2O4 material as the core and FeNi(OH) x as the outer layer, and provides a preparation method. Summary of the Invention
[0004] The purpose of the present invention is to propose a preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst. The prepared electrode material has a hierarchical structure, a large specific surface area, and fully exposed active sites, and has good alkaline electrocatalytic oxygen evolution performance.
[0005] The object of the present invention is achieved by the following technical solutions: A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, the method comprising the following steps: (1) Commercially available nickel foam is ultrasonically cleaned with an aqueous hydrochloric acid solution with a molar concentration of 3 mol / L, acetone, and ethanol for 30 minutes to remove surface oxides, then rinsed thoroughly with deionized water, and dried in vacuo for later use; (2) First, iron nitrate, nickel nitrate, and citric acid are dissolved in ethylene glycol; then polyvinylpyrrolidone (PVP) is added to the solution, and a homogeneous solution is obtained under stirring at room temperature; subsequently, the resulting solution is transferred to a reaction kettle, and nickel foam is placed in it. After sealing the reaction kettle, it is placed in an oven for hydrothermal deposition reaction; (3) After the reaction is completed, the nickel foam deposited with iron-nickel compounds is washed several times with deionized water and ethanol, and vacuum dried in an oven at 60 °C for 10 hours; then the dried sample is heat-treated in a tubular furnace under an argon or nitrogen atmosphere to obtain nickel foam supported magnetic NiFe2O4; (4) Finally, a second hydrothermal treatment is carried out according to the method of step (2) to obtain nickel foam supported core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst.
[0006] The preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, the nickel foam in the above step (1) is industrial nickel foam with a nickel content of 98 - 100%.
[0007] The preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, the iron nitrate, nickel nitrate, citric acid, and ethylene glycol in the above step (2) are of industrial grade.
[0008] The preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, in the homogeneous solution in the above step (2), the molar concentration of iron nitrate is 0.02 - 0.1 mol / L, the molar concentration of nickel nitrate is 0.01 - 0.05 mol / L, and the concentration of citric acid is 0.03 - 0.15 mol / L; wherein, the iron / nickel molar ratio is 1.5 - 2.5, and the metal atom / citric acid molar ratio is 0.5 - 1.
[0009] The preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) xPreparation method of electrocatalyst, the mass concentration of polyvinylpyrrolidone in the above step (2) is 0.2% - 2%.
[0010] The described core-shell structured magnetic NiFe2O4@FeNi(OH) x Preparation method of electrocatalyst, the hydrothermal deposition reaction temperature in the above step (2) is 120 - 200 °C, and the reaction time is 2 - 12 hours.
[0011] The described core-shell structured magnetic NiFe2O4@FeNi(OH) x Preparation method of electrocatalyst, the heat treatment temperature in the above step (3) is 300 - 600 °C, and the reaction time is 1 - 5 hours.
[0012] The present invention has the following advantages and effects: The nickel foam supported core-shell structured magnetic NiFe2O4@FeNi(OH) of the present invention x ; This electrode material has a multi-level structure, a large specific surface area and fully exposed active sites. This electrode material has good alkaline electrocatalytic oxygen evolution performance. The raw materials of the synthesis method of this material are inexpensive, the operation is simple, and it is suitable for industrial production. Description of the drawings
[0013] Figure 1 Is the XRD pattern of nickel foam supported magnetic NiFe2O4@FeNi(OH) x ; Figure 2 Is the scanning electron microscope photograph of nickel foam supported magnetic NiFe2O4@FeNi(OH) x ; Figure 3 Is the high-resolution transmission electron microscope photograph of magnetic NiFe2O4@FeNi(OH) x particles; Figure 4 Is the magnetization curve of magnetic NiFe2O4@FeNi(OH) x particles; Figure 5 Is the oxygen evolution linear voltammetry curve of the electrode materials prepared at different hydrothermal temperatures; Figure 6 Is the oxygen evolution linear voltammetry curve of the electrode materials prepared at different hydrothermal times; Figure 7 Is the oxygen evolution linear voltammetry curve of the electrode materials prepared at different heat treatment temperatures. Detailed implementation manners
[0014] The present invention will be described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments. It should be noted that all other embodiments within the scope of the claims of the present invention and without outstanding creativity listed in this specification should belong to the protection scope of the present invention.
[0015] A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, comprising the following steps: (1) Pretreatment of the nickel foam substrate The commercial nickel foam was ultrasonically cleaned with hydrochloric acid aqueous solution with a molar concentration of 3 mol / L, acetone and ethanol for 30 minutes respectively to remove the surface oxides, then rinsed with deionized water and dried in vacuum for later use; (2) Solution preparation Using ferric nitrate and nickel nitrate as metal sources, citric acid as a complexing agent, and polyvinylpyrrolidone as a surfactant, a solution was prepared with ethylene glycol as a solvent: in the solution, the molar concentration of ferric nitrate was 0.02 - 0.1 mol / L, the molar concentration of nickel nitrate was 0.01 - 0.05 mol / L, the concentration of citric acid was 0.03 - 0.15 mol / L, and the mass concentration of polyvinylpyrrolidone was 0.2% - 2%. Among them, the iron / nickel molar ratio was 1.5 - 2.5, and the metal atom / citric acid molar ratio was 0.5 - 1.
[0016] (3) Hydrothermal deposition reaction The nickel foam treated in (1) and the solution obtained in (2) were transferred into a reaction kettle for hydrothermal deposition reaction. The reaction temperature was 120 - 200 °C, and the heat preservation time was 2 - 12 hours to obtain a nickel foam supported FeNi(OH) x precursor; (4) Heat treatment The nickel foam supported FeNi(OH) x precursor was placed in a tube furnace and heat-treated in an argon or nitrogen atmosphere. The heat treatment temperature was 300 - 600 °C, and the heat preservation time was 1 - 5 hours to obtain a nickel foam supported NiFe2O4 material.
[0017] (5) Secondary hydrothermal The second hydrothermal treatment was carried out according to the methods of steps (2) and (3) above to obtain a nickel foam supported core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst. The conditions of the secondary hydrothermal treatment do not have to be the same as those of the first hydrothermal treatment. Embodiment
[0018] (1) Pretreatment of the nickel foam substrate The commercial nickel foam was ultrasonically cleaned with hydrochloric acid aqueous solution with a molar concentration of 3 mol / L, acetone and ethanol for 30 minutes to remove the surface oxides, and then rinsed with deionized water and dried in vacuum for later use; (2)Solution preparation Using ferric nitrate and nickel nitrate as metal sources, citric acid as a complexing agent, and polyvinylpyrrolidone as a surfactant, a solution was prepared with ethylene glycol as the solvent: in the solution, the molar concentration of ferric nitrate was 0.05 mol / L, the molar concentration of nickel nitrate was 0.025 mol / L, the concentration of citric acid was 0.075 mol / L, and the mass concentration of polyvinylpyrrolidone was 0.5%. Among them, the iron / nickel molar ratio was 2, and the metal atom / citric acid molar ratio was 1.
[0019] (3)Hydrothermal deposition reaction The nickel foam treated in (1) and the solution obtained in (2) were transferred into a reaction kettle for hydrothermal deposition reaction. The reaction temperature was 180 °C and the hydrothermal time was 10 hours to obtain a nickel foam supported FeNi(OH) x precursor; (4)Heat treatment The nickel foam supported FeNi(OH) x precursor obtained in (3) was placed in a tubular furnace and heat-treated in an argon atmosphere. The heat treatment temperature was 500 °C and the holding time was 2 hours to obtain a nickel foam supported NiFe2O4 material.
[0020] (5)Secondary hydrothermal The second hydrothermal reaction was carried out according to the methods in steps (2) and (3) above, and the hydrothermal time was changed to 3 hours to obtain a nickel foam supported core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst.
[0021] The structural characterization and performance testing of the present invention are as follows in the figure: Figure 1 The XRD curve in it proves that the prepared sample is mainly composed of NiFe2O4 and FeNi(OH) x constitute.
[0022] Figure 2 The scanning electron microscope photos of the prepared electrode material in it show that the magnetic NiFe2O4@FeNi(OH) x particles are spherical-like materials composed of flaky structures, and the flaky structures are assembled by nanoparticles.
[0023] Figure 3 The transmission electron microscope photos in it prove that the NiFe2O4@FeNi(OH) x particles have a core-shell structure.
[0024] Figure 4 The magnetization curve in x proves that NiFe2O4@FeNi(OH)
[0025] Figure 5 particles have magnetic characteristics. Example 1
[0026] Steps (1) and (2) are the same as those in Example 1; The difference in step (3) from Example 1 is that the hydrothermal reaction temperature is 140 °C; Steps (4) and (5) and the characterization results are the same as those in Example 1. The performance results are shown in Figure 5 . Example 2
[0027] Steps (1) and (2) are the same as those in Example 1; The difference in step (3) from Example 1 is that the hydrothermal reaction temperature is 160 °C; Steps (4) and (5) and the characterization results are the same as those in Example 1. The performance results are shown in Figure 5 . Example 3
[0028] Steps (1) and (2) are the same as those in Example 1; The difference in step (3) from Example 1 is that the hydrothermal reaction time is 8 hours; Steps (4) and (5) and the characterization results are the same as those in Example 1. The performance results are shown in Figure 6 . Example 4
[0029] Steps (1) and (2) are the same as those in Example 1; The difference in step (3) from Example 1 is that the hydrothermal reaction time is 12 hours; Steps (4) and (5) and the characterization results are the same as those in Example 1. The performance results are shown in Figure 6 . Example 5
[0030] Steps (1), (2), and (3) are the same as those in Example 1; The difference in step (4) from Example 1 is that the heat treatment temperature is 300 °C; Step (5) and the characterization results are the same as those in Example 1. The performance results are shown in Figure 7 . Example 6
[0031] Steps (1), (2), and (3) are the same as those in Example 1; Step (4) is different from Example 1 in that the heat treatment temperature is 400 °C; Steps (5) and the characterization results are the same as those in Example 1, and the performance results are shown in Figure 7 .
Claims
1. Preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The method includes the following steps: (1) Ultrasonically clean commercial nickel foam with hydrochloric acid aqueous solution with a molar concentration of 3 mol / L, acetone, and ethanol for 30 minutes to remove surface oxides, then rinse it with deionized water, and set it aside after vacuum drying; (2) First, dissolve iron nitrate, nickel nitrate, and citric acid in ethylene glycol; then add polyvinylpyrrolidone (PVP) to the solution to obtain a homogeneous solution under stirring at room temperature; subsequently, transfer the obtained solution to a reaction kettle and place nickel foam in it. After sealing the reaction kettle, place it in an oven for hydrothermal deposition reaction; (3) After the reaction is completed, wash the nickel foam deposited with iron-nickel compounds several times with deionized water and ethanol, and vacuum dry it in an oven at 60 °C for 10 hours; then heat-treat the dried sample in a tubular furnace under an argon or nitrogen atmosphere to obtain nickel foam-supported magnetic NiFe2O4; (4) Finally, perform the second hydrothermal treatment according to the method in step (2) to obtain a core-shell structured magnetic NiFe2O4@FeNi(OH) supported on nickel foam x electrocatalyst.
2. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The nickel foam in the above step (1) is industrial nickel foam with a nickel content of 98 - 100%.
3. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The iron nitrate, nickel nitrate, citric acid, and ethylene glycol in the above step (2) are of industrial grade.
4. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that In the homogeneous solution in the above step (2), the molar concentration of iron nitrate is 0.02 - 0.1 mol / L, the molar concentration of nickel nitrate is 0.01 - 0.05 mol / L, and the concentration of citric acid is 0.03 - 0.15 mol / L; among them, the iron / nickel molar ratio is 1.5 - 2.5, and the metal atom / citric acid molar ratio is 0.5 - 1.
5. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The mass concentration of polyvinylpyrrolidone in the above step (2) is 0.2% - 2%.
6. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The hydrothermal deposition reaction temperature in the above step (2) is 120 - 200 °C, and the reaction time is 2 - 12 hours.
7. A preparation method of a core-shell structured magnetic NiFe2O4@FeNi(OH) x electrocatalyst, characterized in that The heat treatment temperature in the above step (3) is 300 - 600 °C, and the reaction time is 1 - 5 hours.