Ferrocobalt-based self-supporting oxygen evolution electrode and preparation method and application thereof

Abstract

The invention discloses a ferrocobalt-based self-supporting oxygen evolution electrode and a preparation method and application thereof, and belongs to the technical field of electrodes. The electrode is obtained by growing a layer of needle-like ferrocobalt layered double hydroxide catalyst on the surface of foamed nickel through a simple solution immersion-etching method and through preparation of a precursor solution. The preparation method comprises the following steps: mixing an isopropanol solution of cobalt nitrate with a ferrous sulfate aqueous solution, and putting a nickel-based substrate into the solution for immersion etching, so as to obtain the cobalt-iron layered double hydroxide catalyst electrode. The preparation method disclosed by the invention is mature and simple in process route, mild in condition, easy to control and easy to amplify, and the oxygen evolution (OER) catalytic activity of the nickel-based catalyst is also remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of electrode technology, and more specifically, to a cobalt-iron-based self-supporting oxygen evolution electrode and a preparation method and application thereof. Background Art

[0002] Water electrolysis technology is a key pathway for renewable energy conversion and storage. The oxygen evolution reaction (OER), the anodic half-reaction, is a bottleneck limiting its efficiency due to its complex kinetics involving four-electron transfer. Developing low-cost, highly active, and stable oxygen evolution electrode materials is a key goal in promoting the large-scale application of water electrolysis technology.

[0003] While noble metal-based catalysts (such as IrO₂ and RuO₂) exhibit excellent OER catalytic performance, their scarcity and high cost severely limit their practical applications. Consequently, current research focuses on non-noble metal-based materials, particularly cobalt-iron-based compounds (such as hydroxides, oxides, and layered double hydroxides), whose unique d-electron configurations and synergistic effects can effectively reduce the OER overpotential. However, conventional powdered catalysts rely on binders to support conductive substrates, leading to high interfacial resistance and insufficient long-term stability.

[0004] Self-supporting electrodes have become a research hotspot in recent years because they do not require additional binders, can achieve direct electron conduction between the catalyst and the substrate, and optimize the mass transfer path through a three-dimensional porous structure. For example, the cobalt-iron-based self-supporting electrodes prepared by electrodeposition, hydrothermal synthesis or metal-organic framework derivatization have improved the catalytic performance to a certain extent, but still have the following technical difficulties: 1. Weak interface bonding: The interface between the catalyst and the substrate is easily detached due to volume expansion or electrolyte erosion, affecting long-term stability; 2. Complex preparation process: high-temperature calcination, multi-step etching and other processes increase production costs, and may cause the porous structure to collapse and reduce the specific surface area. In addition, the conductivity of cobalt-iron-based materials is relatively weak, and their electron transfer efficiency still needs to be further optimized through structural design. How to construct a self-supporting oxygen evolution electrode with high active site density, strong interface coupling and excellent conductivity through a simple and efficient preparation method is still a technical problem that needs to be solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a preparation method and application of a cobalt-iron-based self-supporting oxygen evolution electrode. By regulating the precursor ratio and growth process, a cobalt-iron composite catalytic layer with a porous structure is in situ generated on the surface of a conductive substrate, thereby achieving efficient exposure of active sites, rapid conduction of electrons and improved structural stability, providing a new path for the preparation of low-cost, high-performance oxygen evolution electrodes.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode comprises the following steps: mixing a divalent cobalt ion salt solution and a ferrous ion salt solution to obtain a precursor solution; placing a nickel-based substrate in the precursor solution for immersion etching, repeatedly rinsing the nickel-based substrate after the reaction with water, and drying to obtain a cobalt-iron based self-supporting oxygen evolution electrode.

[0008] The present invention is further configured to prepare a divalent cobalt ion salt solution using an organic solvent, wherein the organic solvent is one of isopropyl alcohol, isobutyl alcohol, glycerol, and ethylene glycol, and the concentration of the divalent cobalt ion salt solution is 0.1 mol / L~0.8 mol / L.

[0009] The present invention is further configured such that the divalent cobalt ion salt is one of cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate.

[0010] The present invention is further configured to use distilled water to prepare the ferrous ion salt solution, and the concentration of the ferrous ion salt solution is 0.08 mol / L~0.8 mol / L.

[0011] The present invention is further configured such that the ferrous ion salt is one of ferrous nitrate, ferrous sulfate, ferrous chloride, and ferrous acetate.

[0012] The present invention is further configured such that the molar ratio of the divalent cobalt ions in the divalent cobalt ion salt solution to the ferrous ions in the ferrous ion salt solution is 7:1 to 1:7; and the volume ratio of the divalent cobalt ion salt solution to the ferrous ion salt solution is 3:1 to 1:3.

[0013] The present invention is further configured such that the nickel-based substrate is one of nickel mesh, nickel foam, and nickel plate; the nickel-based substrate is first ultrasonically treated in an acid solution, then rinsed with deionized water to neutrality, and then placed in a precursor solution for immersion etching.

[0014] The present invention is further configured such that the immersion time is 2 hours to 48 hours.

[0015] A cobalt-iron based self-supporting oxygen evolution electrode prepared by the above preparation method.

[0016] The invention relates to the application of a cobalt-iron-based self-supporting oxygen evolution electrode in photocatalytic hydrolysis, electrocatalytic hydrolysis, alkaline water electrolysis to produce hydrogen and prepare fuel cells.

[0017] In summary, the present invention has the following beneficial effects:

[0018] 1. The present invention provides a method for preparing a cobalt-iron based self-supporting oxygen evolution electrode. First, Co 2+ Ionic salts and Fe 2+ Ionic salts were dissolved in organic solution and water, and then Fe 2+Ionic salts are added to Co 2+ The ionic salt solution is uniformly mixed, and then the nickel-based substrate is placed in the precursor solution to in situ grow a layer of cobalt-iron layered double hydroxide on the substrate (wherein, the ratio of organic solution and water is adjusted to control the nucleation rate of cobalt-iron layered double hydroxide); at the same time, through Fe 2+ During the immersion process, the ions are converted into Fe 3+ , the Fe 3+ A replacement reaction occurs with the nickel-based substrate, thereby producing a bonding layer between the catalyst and the nickel-based substrate, significantly enhancing the bonding force between the catalyst and the electrode substrate, promoting stable performance, and thus obtaining a cobalt-iron-based self-supporting oxygen evolution electrode.

[0019] 2. The preparation method of the present invention adopts simple immersion etching, which not only has a mature and simple process route and mild conditions, but is also easy to control and scale up. It also significantly improves the oxygen evolution catalytic activity of the nickel-based catalyst, providing strong technical support for the development and application of alkaline water electrolysis anodes.

[0020] 3. The cobalt-iron based self-supporting oxygen evolution electrode prepared by the present invention has excellent oxygen evolution performance. 2+ / Co 3+ with Fe 2+ / Fe 3+ The redox couple forms a synergistic effect, and the adsorption energy of key OER intermediates (such as *O, *OH, *OOH) is reduced by adjusting the d-band electron distribution. The introduction of Fe can break the symmetry of the Co site, forming a low-coordination active center, accelerating the OH - At the same time, the needle-like nanostructure provides more edge active sites, significantly improving the OER performance in alkaline water (in 1 mol / L potassium hydroxide solution, 100 mA / cm 2 The oxygen production overpotential at the current density is only 260mV; 200 mA / cm 2 The oxygen production overpotential at this current density is only 290 mV). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an electron microscope image of the cobalt-iron-based self-supporting oxygen evolution electrode in Example 1 of the present invention at a magnification of 2000 times;

[0022] Figure 2 2 is a cross-sectional view of a cobalt-iron-based self-supporting oxygen evolution electrode according to Example 1 of the present invention;

[0023] Figure 3 LSV curves of the OER of the electrodes prepared in Example 1, Examples 10 to 14, and Comparative Example 1 of the present invention;

[0024] Figure 4 1 is the Raman map of the electrodes in Example 1, Example 2 and Example 3 of the present invention;

[0025] Figure 5 Graph showing the stability test results of the electrode in Example 1 of the present invention in a 3M KOH solution under a two-electrode system;

[0026] Figure 6 This is the impedance spectrum of the electrode at different voltages in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The method for preparing the cobalt-iron-based self-supporting oxygen evolution electrode of the present invention comprises the following steps:

[0029] S1. Ultrasonic treatment of a nickel-based substrate in a 3 mol / L hydrochloric acid solution for 5-10 min, followed by rinsing with deionized water until the pH is neutral, to obtain a treated nickel-based substrate, which is then stored in anhydrous ethanol;

[0030] S2, dissolving a divalent cobalt ion salt in an organic solvent (preferably a divalent cobalt ion salt selected from cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt acetate, and preferably a ferrous ion salt selected from isopropyl alcohol, isobutyl alcohol, glycerol, and ethylene glycol), and dissolving a ferrous ion salt in distilled water (preferably a ferrous nitrate, ferrous sulfate, ferrous chloride, and ferrous acetate) to obtain a divalent cobalt ion salt solution having a concentration of 0.1 mol / L to 0.8 mol / L and a ferrous ion salt solution having a concentration of 0.08 mol / L to 0.8 mol / L;

[0031] S3, adding the ferrous ion salt solution to the divalent cobalt ion salt solution while stirring to obtain a precursor solution, controlling the molar ratio of the divalent cobalt ions in the divalent cobalt ion salt solution to the ferrous ions in the ferrous ion salt solution to be 7:1-1:7, and the volume ratio of the divalent cobalt ion salt solution to the ferrous ion salt solution to be 3:1-1:3;

[0032] S4. Immerse the treated nickel-based substrate (preferably one of nickel mesh, nickel foam, and nickel plate) in the precursor solution for 2 to 48 hours, then rinse with deionized water, and dry in an oven at 60°C overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode that can be used in photocatalytic hydrolysis, electrocatalytic hydrolysis, alkaline water electrolysis to produce hydrogen, and the preparation of fuel cells.

[0033] Example 1

[0034] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode comprises the following steps:

[0035] S1. Ultrasonicate a 1 cm × 1 cm nickel mesh in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. Store the washed nickel mesh in anhydrous ethanol for later use.

[0036] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate;

[0037] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution to the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution;

[0038] S4. Immerse the treated nickel mesh in the precursor solution for 24 hours, then rinse with deionized water and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0039] Example 2

[0040] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount of cobalt nitrate hexahydrate is changed into cobalt chloride hexahydrate, which specifically comprises the following steps:

[0041] S1. Ultrasonicate a 1 cm × 1 cm nickel mesh in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. Store the washed nickel mesh in anhydrous ethanol for later use.

[0042] S2. Dissolve 0.67 g of cobalt chloride hexahydrate in 24 mL of isopropyl alcohol and stir to completely dissolve it to obtain an organic solution of cobalt chloride; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate;

[0043] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution to the organic solution of cobalt chloride to mix them evenly to obtain a precursor solution;

[0044] S4. Immerse the treated nickel mesh in the above precursor solution for 24 hours, then rinse with deionized water, and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0045] Example 3

[0046] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode, which is the same as the preparation steps of Example 2, except that in step S2, Fe is kept 2+ The molar amount of ferrous sulfate heptahydrate is changed into ferrous chloride hexahydrate, which specifically comprises the following steps:

[0047] S1. Ultrasonicate a 1 cm × 1 cm nickel mesh in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. Store the washed nickel mesh in anhydrous ethanol for later use.

[0048] S2. Dissolve 0.67 g of cobalt chloride hexahydrate in 24 mL of isopropyl alcohol and stir to completely dissolve it to obtain an organic solution of cobalt chloride; dissolve 0.17 g of ferrous chloride hexahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous chloride;

[0049] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous chloride aqueous solution to the organic solution of cobalt chloride to mix them evenly to obtain a precursor solution;

[0050] S4. Immerse the treated nickel mesh in the above precursor solution for 24 hours, then rinse with deionized water, and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0051] Example 4

[0052] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode, which has the same preparation steps as Example 1, except that, in step S2, the concentrations of the organic solution of cobalt nitrate and the aqueous solution of ferrous sulfate are kept unchanged, and the volume ratio of the organic solution of cobalt nitrate and the aqueous solution of ferrous sulfate is replaced with 1:1. The method specifically comprises the following steps:

[0053] S1. Ultrasonicate a nickel mesh with a size of 1 cm × 1 cm in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. The washed nickel mesh is stored in anhydrous ethanol for later use.

[0054] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropyl alcohol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.60 g of ferrous sulfate heptahydrate in 24 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0055] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0056] S4. Immerse the treated nickel mesh in the above precursor solution for 24 hours, then rinse with deionized water, and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0057] Example 5

[0058] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode is the same as the preparation steps in Example 1, except that in step S2, the concentrations of the organic solution of cobalt nitrate and the aqueous solution of ferrous sulfate are kept unchanged, and the volume ratio is changed to 1:3. The method specifically comprises the following steps:

[0059] S1. Ultrasonicate a nickel mesh with a size of 1 cm × 1 cm in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. The washed nickel mesh is stored in anhydrous ethanol for later use.

[0060] S2. Dissolve 0.27 g of cobalt nitrate hexahydrate in 8 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.60 g of ferrous sulfate heptahydrate in 24 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0061] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0062] S4. Immerse the treated nickel mesh in the above precursor solution for 24 hours, then rinse with deionized water, and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0063] Example 6

[0064] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode, which has the same preparation steps as Example 1, except that in step S4, the immersion time is replaced by 2 hours from 24 hours, comprises the following steps:

[0065] S1. Ultrasonicate a nickel mesh with a size of 1 cm × 1 cm in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. The washed nickel mesh is stored in anhydrous ethanol for later use.

[0066] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0067] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0068] S4. Immerse the treated nickel mesh in the above precursor solution for 2 hours, then rinse with deionized water, and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0069] Example 7

[0070] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode is the same as the preparation steps in Example 1, except that in step S4, the immersion time is replaced by 48 hours from 24 hours. The method specifically comprises the following steps:

[0071] S1. Ultrasonicate a nickel mesh with a size of 1 cm × 1 cm in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. The washed nickel mesh is stored in anhydrous ethanol for later use.

[0072] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0073] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0074] S4. Immerse the treated nickel mesh in the above precursor solution for 48 hours, then rinse with deionized water and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0075] Example 8

[0076] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode is the same as the preparation steps in Example 1, except that in step S1, the nickel-based substrate is replaced by nickel foam instead of nickel mesh. The method specifically includes the following steps:

[0077] S1. Ultrasonic treatment of nickel foam with a size of 1 cm×1 cm in a 3 mol / L hydrochloric acid solution for 10 min was performed, and then the ultrasonicated nickel foam was rinsed with deionized water until the pH value was 7. The washed nickel foam was stored in anhydrous ethanol for future use.

[0078] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0079] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0080] S4. Immerse the treated nickel foam in the precursor solution for 48 hours, then rinse with deionized water and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0081] Example 9

[0082] A method for preparing a cobalt-iron-based self-supporting oxygen evolution electrode is the same as the preparation steps in Example 1, except that in step S1, the nickel-based substrate is replaced by a nickel plate instead of a nickel mesh. The method specifically includes the following steps:

[0083] S1. Ultrasonicate a 1 cm × 1 cm nickel plate in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel plate with deionized water until the pH reaches 7. Store the washed nickel plate in anhydrous ethanol for later use.

[0084] S2. Dissolve 0.82 g of cobalt nitrate hexahydrate in 24 mL of isopropanol and stir to completely dissolve it to obtain an organic solution of cobalt nitrate; dissolve 0.20 g of ferrous sulfate heptahydrate in 8 mL of distilled water and stir to completely dissolve it to obtain an aqueous solution of ferrous sulfate.

[0085] S3. Under vigorous stirring, slowly dropwise add the above-mentioned ferrous sulfate aqueous solution into the organic solution of cobalt nitrate to mix them evenly to obtain a precursor solution.

[0086] S4. Immerse the treated nickel plate in the precursor solution for 48 hours, then rinse with deionized water and dry in an oven at 60° C. overnight to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

[0087] Example 10

[0088] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount remains unchanged, and the molar ratio of divalent cobalt ions and ferrous ions is changed to 7:1.

[0089] Example 11

[0090] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount remains unchanged, and the molar ratio of divalent cobalt ions and ferrous ions is changed to 2:1.

[0091] Example 12

[0092] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount remains unchanged, and the molar ratio of divalent cobalt ions and ferrous ions is changed to 1:1.

[0093] Example 13

[0094] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount remains unchanged, and the molar ratio of divalent cobalt ions and ferrous ions is changed to 1:2.

[0095] Example 14

[0096] A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode is the same as the preparation steps of Example 1, except that in step S2, the Co 2+ The molar amount remains unchanged, and the molar ratio of divalent cobalt ion and ferrous ion is changed to 1:3.

[0097] Comparative Example 1

[0098] Preparation method of CoFe LDH by hydrothermal method:

[0099] S1. Ultrasonicate a 1 cm × 1 cm nickel mesh in a 3 mol / L hydrochloric acid solution for 10 min, then rinse the ultrasonicated nickel mesh with deionized water until the pH reaches 7. Store the washed nickel mesh in anhydrous ethanol for later use.

[0100] S2. According to the molar ratio of divalent cobalt ion to ferrous ion of 2:1, weigh 0.002 mol Co(NO3)2·6H2O and 0.001 mol Fe(NO3)3·9H2O, dissolve them in 40 mL of deionized water and stir until completely dissolved; take another 0.03 mol urea and dissolve it in 10 mL of deionized water, slowly add the urea solution to the metal salt solution, and continue stirring to obtain a precursor solution;

[0101] S3. Place the treated nickel mesh vertically into a 50 mL polytetrafluoroethylene-lined autoclave, pour in the precursor solution, ensure that the nickel mesh is completely immersed in the precursor solution, seal the autoclave, and place it in a constant temperature drying oven. Heat it to 140°C at a rate of 5°C / min, keep it warm for 10 hours, and cool it naturally to room temperature after the reaction is completed.

[0102] S4. Take out the nickel mesh, rinse it alternately with deionized water and ethanol 5 times to remove residual reagents, and place it in a vacuum drying oven at 60° C. for 12 hours to obtain a CoFe LDH sample loaded on the nickel mesh.

[0103] Figure 1 This is a 2000-fold magnification electron microscope image of the cobalt-iron-based self-supporting oxygen evolution electrode in Example 1 of the present invention. Figure 1 It is concluded that after the immersion reaction, the surface of the nickel-based nickel mesh of the present invention presents uniform nanoparticles and a needle-like structure.

[0104] Figure 2 This is a cross-sectional view of the cobalt-iron based self-supporting oxygen evolution electrode in Example 1 of the present invention. Figure 2 It is concluded that there is an obvious transition bonding layer between the surface of the nickel mesh of the nickel-based substrate of the present invention and the catalyst layer, and the bonding layer can promote a firm bond between the catalyst and the substrate.

[0105] Figure 3 The LSV curves of the OER of the electrodes prepared in Example 1, Example 10 to Example 14, and Comparative Example 1 of the present invention are shown. Figure 3 It was found that by adjusting the mass concentration ratio of the precursor cobalt nitrate and ferrous sulfate solution, the electrodes obtained all had excellent OER performance, which was much better than the cobalt-iron layered double hydroxide electrode prepared by the hydrothermal method. And changing the ratio had little effect on the OER performance of the catalyst. Among them, the cobalt-iron based self-supporting oxygen evolution electrode of Example 1 had the best performance: at 100 mA / cm 2 The oxygen production overpotential at the current density is only 260mV; 200 mA / cm 2 The oxygen production overpotential at this current density is only 290 mV.

[0106] Figure 4 The Raman images of the electrodes in Examples 1, 2 and 3 of the present invention are shown in FIG. Figure 4 The results show that the catalyst electrodes prepared by replacing different precursor materials remain basically consistent. This method shows good uniformity.

[0107] Figure 5 This is a stability test of the electrode in Example 1 of the present invention in a 3M KOH solution under a two-electrode system. Figure 5 It is found that at a high current density of 1A cm -2 Under these conditions, the electrolytic cell with the prepared catalyst electrode as the anode can maintain a relatively constant cell voltage for more than 100 hours.

[0108] Figure 6 The impedance spectrum of the electrode at different voltages in Example 1 of the present invention is shown in FIG. Figure 6 It was concluded that the impedance gradually decreased with the increase of applied potential, indicating that the interfacial electron transport performance continued to increase with the application of voltage.

[0109] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a cobalt-iron based self-supporting oxygen evolution electrode, characterized in that: The following steps are involved: mixing a divalent cobalt ion salt solution and a ferrous ion salt solution to obtain a precursor solution; The nickel-based substrate is placed in a precursor solution for immersion etching, and the nickel-based substrate after the reaction is repeatedly rinsed with water and dried to obtain a cobalt-iron-based self-supporting oxygen evolution electrode.

2. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: A divalent cobalt ion salt solution is prepared by using an organic solvent, wherein the organic solvent is one of isopropyl alcohol, isobutyl alcohol, glycerol, and ethylene glycol, and the concentration of the divalent cobalt ion salt solution is 0.1 mol / L to 0.8 mol / L.

3. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The divalent cobalt ion salt is one of cobalt nitrate, cobalt sulfate, cobalt chloride and cobalt acetate.

4. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The ferrous ion salt solution is prepared using distilled water, and the concentration of the ferrous ion salt solution is 0.08 mol / L to 0.8 mol / L.

5. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The ferrous ion salt is one of ferrous nitrate, ferrous sulfate, ferrous chloride and ferrous acetate.

6. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The molar ratio of divalent cobalt ions in the divalent cobalt ion salt solution to ferrous ions in the ferrous ion salt solution is 7:1-1:7; and the volume ratio of the divalent cobalt ion salt solution to the ferrous ion salt solution is 3:1-1:

3.

7. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The nickel-based substrate is one of nickel mesh, nickel foam and nickel plate. The nickel-based substrate is first ultrasonically treated in an acid solution, then rinsed with deionized water until neutral, and then placed in a precursor solution for immersion etching.

8. The method for preparing a cobalt-iron based self-supporting oxygen evolution electrode according to claim 1, characterized in that: The immersion time is 2h~48h.

9. A cobalt-iron based self-supporting oxygen evolution electrode prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the cobalt-iron based self-supporting oxygen evolution electrode according to any one of claims 1 to 8 in photocatalytic hydrolysis, electrocatalytic hydrolysis, alkaline water electrolysis for hydrogen production and in the preparation of fuel cells.

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