Self-supporting amorphous hydroxyl ferronickel oxide coated nickel cobaltate heterojunction electro-catalysis composite material as well as preparation and application thereof

Abstract

The invention discloses a self-supporting amorphous hydroxyl ferronickel oxide coated nickel cobaltate heterojunction electro-catalysis composite material as well as preparation and application thereof. Nickel chloride, cobalt chloride and ferric chloride are used as a nickel source, a cobalt source and an iron source respectively, urea is used as a precipitator, and the foamed nickel self-supporting amorphous hydroxyl nickel iron oxide coated nickel cobaltate heterojunction electro-catalysis composite material # imgabs0 is obtained through a hydrothermal method and a dipping-corrosion method. The method is simple and convenient to operate, low in preparation cost, short in reaction period and high in repeatability, and raw materials are easy to obtain. The material shows excellent oxygen evolution performance in the field of electro-catalytic water decomposition. In a 1 M KOH (pH = 14) electrolyte solution, under the condition that the current density is 10 mA. Cm <-2 >, only the overpotential of 219.6 mV is needed, the oxygen evolution reaction can be stably carried out for 100 hours under the current density of 100 mA. Cm <-2 >, the performance is not remarkably attenuated, and good stability is shown.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysts, and relates to a preparation method of a self-supporting electrocatalytic composite material of amorphous nickel iron oxyhydroxide-wrapped nickel cobaltate heterojunction, and also relates to its application in the preparation of oxygen evolution catalyst materials and oxygen evolution electrodes, and has potential application value in other fields such as energy development and environmental protection. Background Art

[0002] With the continuous development of society, the social population has always been in a continuous growth trend. At the same time, people's demand for energy is also continuously increasing. In this case, people generally rely on fossil fuels such as coal, oil, and natural gas as the main energy sources. However, this over-reliance on fossil fuels poses a great risk to the upcoming energy crisis and environmental challenges. Fossil fuels are limited resources, and their reserves are continuously decreasing, and there may be a dilemma of energy shortage in the future. Moreover, the use of fossil fuels will produce a large amount of pollutants, causing serious damage to the environment and exacerbating problems such as climate change.

[0003] Hydrogen fuel stands out among many energy sources with its rich sources and excellent heat characteristics, and has become an extremely ideal zero-emission alternative energy carrier. In the context of the increasing requirements for environmental protection and sustainable development, electrochemical water splitting, as an efficient and environmentally friendly method for producing high-purity hydrogen, has attracted much attention. It can give full play to its own advantages and convert electrical energy into hydrogen and oxygen skillfully through the hydrogen evolution reaction and the oxygen evolution reaction. This conversion process is not only efficient but also environmentally friendly, providing new ideas and ways to solve energy problems and environmental challenges, and has broad development prospects. However, both the hydrogen evolution reaction and the oxygen evolution reaction are hindered by slow mass and charge transfer kinetics. In particular, the oxygen evolution reaction, as a four-electron transfer process, will encounter huge energy barriers, thus becoming the key bottleneck of the entire water electrolysis reaction. Therefore, to address this challenge, the rational design of efficient and stable oxygen evolution reaction catalysts is becoming increasingly important for promoting the development of energy conversion technologies. Summary of the Invention

[0004] The present invention addresses the above problems and uses hydrothermal and impregnation-corrosion methods to generate amorphous nickel iron oxyhydroxide-wrapped nanoneedle nickel cobaltate on nickel foam as an oxygen evolution electrocatalyst. This method is simple to operate, the raw materials are easy to obtain, the preparation cost is low, the reaction cycle is short, and the repeatability is high. The product has good oxygen evolution performance. In 1.0 M KOH electrolyte, when its oxygen evolution overpotential is 219.6 mV, the current density is 10 mA / cm 2 , and it can stably evolve oxygen for up to 100 hours at a current density of 100 mA / cm 2 , and it is a well-performing and stable electrocatalytic oxygen evolution reaction catalyst.

[0005] To achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0006] In the first aspect of the present invention, a preparation method of a self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material is provided. Nickel chloride, cobalt chloride, and iron chloride are used as the nickel source, cobalt source, and iron source respectively, and urea is used as a precipitating agent. A self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material NiCo2O4@a-NiFeO(OH) is obtained through hydrothermal and impregnation-corrosion methods.

[0007] Specifically, it includes the following steps:

[0008] A. Preparation of nickel cobaltate heterojunction

[0009] Disperse 0.7 - 2.3 parts by weight of nickel chloride hexahydrate, 0.3 - 1.2 parts by weight of cobalt chloride hexahydrate, and 0.3 - 1.0 parts by weight of urea evenly in deionized water, and stir for 30 - 40 min until a clear pink solution is formed; then, transfer the above solution to a stainless-steel hydrothermal autoclave equipped with an inert lining (such as polytetrafluoroethylene), and vertically place the support carrier (preferably nickel foam) into the autoclave; subsequently, keep it warm at 120 - 160 °C for 5 - 12 hours, naturally cool to room temperature, and then wash the support carrier with deionized water and absolute ethanol multiple times; then transfer it to a vacuum drying oven for overnight drying, and place the dried sample in a muffle furnace, and keep it warm at 300 - 450 °C for 2 - 5 hours;

[0010] B. Amorphous nickel-iron oxyhydroxide coating on nickel cobaltate heterojunction

[0011] Mix ferric chloride and nickel chloride in a molar ratio of 1:1 to prepare a mixed solution with a concentration of 50 mM; then, place the support carrier loaded with the nickel cobaltate heterojunction prepared in step A into this mixed solution and impregnate it for 10 - 30 min; after natural drying, wash it repeatedly with deionized water and absolute ethanol, and then place the sample in a vacuum drying oven at 60 - 120 °C for drying to obtain a self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material NiCo2O4@a-NiFeO(OH) / NF.

[0012] In the second aspect of the present invention, a nickel foam self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material is provided, which is prepared by the above method.

[0013] Scanning electron microscopy and transmission electron microscopy images show that in the obtained nickel foam-supported amorphous nickel iron oxyhydroxide-coated nickel cobaltate (NiCo2O4@a-NiFeO(OH) / NF) material, nickel cobaltate forms a nano-needle scaffold structure with a structural width of 180-220 nm; the composite material is composed of two-dimensional nanosheets growing uniformly and coating nickel cobaltate, and amorphous NiFeO(OH) nanosheets are successfully deposited on the surface of NiCo2O4.

[0014] X-ray diffraction analysis can obtain the characteristic peaks of the NiCo2O4 structure; the results of elemental analysis show that Co is mainly distributed in the NiCo2O4 nano-conical structure, while Ni and Fe are uniformly distributed in the entire amorphous NiFeO(OH) nanosheets, thus confirming the formation of a well-defined heterostructure.

[0015] Electrochemical performance test: Using 1.0 mol / L KOH solution as the electrolyte, nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate as the working electrode, silver / silver chloride electrode as the reference electrode, and graphite rod as the counter electrode, the test temperature is 10-30 °C; in 1.0 M KOH electrolyte, when the oxygen evolution overpotential is 219.6 mV, the current density is 10 mA·cm -2 -2, and it can stably evolve oxygen for up to 100 hours at a current density of 100 mA·cm -2 -2, making it a catalyst with good and stable electrocatalytic oxygen evolution reaction performance.

[0016] Therefore, in the third aspect of the present invention, there is provided the application of the above-mentioned self-supporting amorphous nickel iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material in the preparation of an electrocatalytic oxygen evolution electrode.

[0017] In the fourth aspect of the present invention, there is provided an electrocatalytic oxygen evolution electrode, including a carrier and a catalyst material loaded thereon, wherein the catalyst material is a self-supporting amorphous nickel iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material prepared by the method described in any one of the above.

[0018] In the fifth aspect of the present invention, there is provided a method for electrolyzing water, using the above-mentioned electrocatalytic oxygen evolution anode electrode as the working electrode. Preferably, the electrolyte is 1M KOH solution.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) The nickel foam self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite NiCo2O4@a-NiFeO(OH) / NF was synthesized by simple hydrothermal and impregnation-etching methods. The synthesis method is simple, the operation is convenient, the conditions are mild, and the repeatability is high. No complex instruments are required during the synthesis process, and the operation is simple. It can be synthesized in large quantities, which is conducive to large-scale industrial applications.

[0021] (2) The nickel foam self-supporting amorphous nickel-iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite NiCo2O4@a-NiFeO(OH) was used as an oxygen evolution catalyst. The results show that it has good oxygen evolution performance and a low overpotential. In an alkaline solution, when the overpotential is 219.6 mV, the current density can reach 8 - 12 mA·cm -2 , and it can maintain a stable working state for more than 100 hours.

[0022] (3) During the preparation process, all reagents are commercial products and do not require further treatment.

[0023] (4) The synthesis method is simple, and the obtained material is easy to apply, which is conducive to popularization and application in industrial production. It can also be used as an oxygen evolution material in systems such as the chlor-alkali industry, water electrolysis process, solar water electrolysis, and electrochemistry. Description of the Drawings

[0024] Figure 1 are scanning electron microscope images of nickel foam coated with amorphous nickel-iron oxyhydroxide and nickel cobaltate prepared in Example 1 at different magnifications, a, 1μm; b, 500nm;

[0025] Figure 2 are transmission electron microscope images of nickel foam coated with amorphous nickel-iron oxyhydroxide and nickel cobaltate prepared in Example 1 at different magnifications, a, 200nm; b, 20nm;

[0026] Figure 3 is the X-ray diffraction pattern of nickel foam coated with amorphous nickel-iron oxyhydroxide and nickel cobaltate prepared in Example 1;

[0027] Figure 4 is the transmission electron microscope image and the corresponding elemental distribution maps of O, Co, Ni, and Fe of nickel foam coated with amorphous nickel-iron oxyhydroxide and nickel cobaltate prepared in Example 1;

[0028] Figure 5 is the X-ray photoelectron spectroscopy of nickel foam coated with amorphous nickel-iron oxyhydroxide and nickel cobaltate prepared in Example 1;

[0029] Figure 6The linear sweep voltammetry curve of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution;

[0030] Figure 7 The Tafel slope of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution;

[0031] Figure 8 The electrochemical impedance spectroscopy of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution;

[0032] Figure 9 Is the chronopotentiometry curve of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode at a constant current density of 100 mA·cm -2 in an alkaline electrolyte solution; Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0034] The "ranges" disclosed herein are in the form of lower and upper limits. There may be one or more lower limits, and one or more upper limits. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges that can be defined in this way are inclusive and combinable, that is, any lower limit can be combined with any upper limit to form a range. For example, ranges of 100 to 140 and 500 to 900 are listed for a particular parameter, and it is understood that ranges of 100 to 140 and 500 to 900 are also contemplated. Additionally, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 2, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.

[0035] In the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations.

[0036] In the present invention, unless otherwise specified, all the embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions.

[0037] Example 1

[0038] I. Preparation of nickel foam-supported amorphous nickel iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite

[0039] 1.3 g of nickel chloride hexahydrate, 0.6 g of cobalt chloride hexahydrate and 0.5 g of urea were uniformly dispersed in 32 mL of deionized water and stirred for 30 min until a clear solution was formed, and the solution was pink. Then, the above solution was transferred to a stainless-steel hydrothermal autoclave with a polytetrafluoroethylene liner, and nickel foam was vertically placed into the autoclave. Subsequently, it was kept at 130 °C for 6 hours, and after natural cooling to room temperature, nickel foam was washed repeatedly with deionized water and absolute ethanol. Then it was transferred to a vacuum drying oven and dried overnight. Finally, the dried sample was placed in a muffle furnace and kept at 350 °C for 2 hours.

[0040] Iron chloride and nickel chloride were mixed in a ratio of 1:1 to prepare a mixed solution with a concentration of 50 mM. Subsequently, the nickel foam after heat preservation was immersed in this mixed solution for 10 minutes. After that, the soaked nickel foam was left to dry naturally on a porcelain boat. After the sample was dried, it was repeatedly washed with deionized water and absolute ethanol. Then the sample was placed in a vacuum drying oven at 60 °C for drying, and nickel foam coated with nickel iron oxyhydroxide and nickel cobaltate was obtained.

[0041] II. Performance characterization test

[0042] Figure 1 Figure 1 is the scanning electron microscope image of the nickel foam coated with nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1. By observing the morphology of the sample, it was confirmed that the material was cobalt nickelate with a nanoneedle scaffold structure wrapped by uniformly grown two-dimensional nanosheets, and the structural width was 180 - 220 nm.

[0043] Figure 2 Figure 2 is the transmission electron microscope image of the nickel foam coated with nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1, which clearly shows that amorphous NiFeO(OH) nanosheets were successfully deposited on the surface of NiCo2O4, confirming the formation of the composite heterostructure.

[0044] Figure 3 Figure 3 is the X-ray diffraction pattern of the nickel foam coated with nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1. The scanning speed was 2°·min -1 , and the X-ray diffraction pattern with a scanning range of 5° - 80° was identified as the characteristic peaks of the spinel NiCo2O4 structure.

[0045] Figure 4 The transmission electron microscopy images of nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1 and the corresponding elemental distribution maps of O, Co, Ni, and Fe verify the uniform distribution of Ni, Fe, Co, and O elements. Among them, Co is mainly distributed in the NiCo2O4 nanocone structure, while Ni and Fe are uniformly distributed throughout the amorphous NiFeO(OH) nanosheets, thus confirming the formation of a well-defined heterostructure.

[0046] Figure 5 The X-ray photoelectron spectroscopy of nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1. The Ni 2p spectrum proves that nickel is mainly Ni³⁺ and Ni-O bonds, and the increase in the oxidation state of nickel contributes to the oxygen evolution reaction. The O 1s spectrum proves that oxygen mainly exists in the form of lattice oxygen, metal hydroxide, and adsorbed oxygen. The Co 2p spectrum shows that cobalt is mainly Co 2+ 。

[0047] III. Electrochemical performance test

[0048] The nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared was directly used as the working electrode for electrochemical characterization tests. Through a CHI760 electrochemical workstation and a standard three-electrode system, the nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared was placed in a 1.0 M KOH aqueous solution, and linear sweep tests and cyclic performance tests were carried out using conventional methods.

[0049] Specifically, in the environment of conventional water electrolysis for hydrogen production, that is, a 1 molar per liter potassium hydroxide (1.0 M KOH) aqueous solution was used as the electrolyte solution. The above-mentioned nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate was used as the working electrode, a silver-silver chloride electrode was used as the reference electrode, and a graphite rod was used as the counter electrode. The test temperature was 25 °C.

[0050] Figure 6 The oxygen evolution linear sweep curve of the nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution. The curve is a linear sweep curve under the test conditions of using the nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate prepared in Example 1 as the working electrode, a silver-silver chloride electrode as the reference electrode, a graphite rod as the counter electrode, 1.0 M / L KOH as the electrolyte, a test temperature of room temperature, and a scan rate of 5 mV / s. It can be seen from the curve that in an alkaline electrolyte, when the nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate is used as the working electrode, the oxygen evolution overpotential is 219.6 mV and the current density is 10 mA·cm -2 , demonstrating that the nickel foam coated with amorphous nickel iron oxyhydroxide and nickel cobaltate has excellent electrocatalytic oxygen evolution activity.

[0051] Figure 7 The Tafel slope of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution. The data shows that the Tafel slope of the sample is only 46.96 mV dec - ¹.

[0052] Figure 8 The electrochemical impedance spectrum of nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution. The data shows that nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate has a low charge transfer resistance, further confirming its excellent electron transfer ability.

[0053] Figure 9 For nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate prepared in Example 1 as the working electrode in an alkaline electrolyte solution at 100 mA·cm -2 Chronopotentiometry curve at a constant current density. The test shows that nickel foam wrapped with amorphous nickel iron oxyhydroxide coated with nickel cobaltate can remain stable for 100 hours at a current density of 100 mA·cm - ², indicating its excellent electrochemical stability.

[0054] Compared with the existing preparation methods of electrocatalytic oxygen evolution materials, the present invention has the following advantages: simple synthesis process, wide selection of raw materials, low cost, high electrocatalytic oxygen evolution activity, and good stability.

[0055] Example 2

[0056] 0.7 g of nickel chloride hexahydrate, 0.3 g of cobalt chloride hexahydrate and 0.3 g of urea were uniformly dispersed in 30 mL of deionized water, and stirred for 30 min until a clear solution was formed, and the solution showed a pink color. Then, the above solution was transferred to a stainless steel hydrothermal autoclave with a polytetrafluoroethylene liner, and the nickel foam was vertically placed in the autoclave. Subsequently, it was kept at 120 °C for 5 hours, and after naturally cooling to room temperature, the nickel foam was washed repeatedly with deionized water and absolute ethanol. Then it was transferred to a vacuum drying oven and dried overnight. Finally, the dried sample was placed in a muffle furnace and kept at 300 °C for 2 hours.

[0057] Mix ferric chloride and nickel chloride in a ratio of 1:1 to prepare a mixed solution with a concentration of 50 mM. Subsequently, place the heat-insulated nickel foam into this mixed solution for impregnation, and the impregnation time is 10 minutes. After that, place the impregnated nickel foam on a porcelain ark and let it dry naturally. After the sample is dried, wash it repeatedly with deionized water and absolute ethanol. Subsequently, place the sample in a vacuum drying oven at 60 °C for drying, and nickel foam wrapped with amorphous nickel iron oxyhydroxide and nickel cobaltate is obtained. The characteristics and properties are similar to those of Example 1.

[0058] Example 3

[0059] Uniformly disperse 2.3 g of nickel chloride hexahydrate, 1.2 g of cobalt chloride hexahydrate and 1.0 g of urea in 60 mL of deionized water, and stir for 30 min until a clear solution is formed, and the solution appears pink. Then, transfer the above solution to a stainless steel hydrothermal autoclave with a polytetrafluoroethylene inner liner, and vertically place the nickel foam into the autoclave. Subsequently, keep it at 160 °C for 12 hours, and after natural cooling to room temperature, wash the nickel foam with deionized water and absolute ethanol for many times. Then transfer it to a vacuum drying oven for overnight drying. Finally, place the dried sample in a muffle furnace and keep it at 450 °C for 5 hours.

[0060] Mix ferric chloride and nickel chloride in a ratio of 1:1 to prepare a mixed solution with a concentration of 50 mM. Subsequently, place the heat-insulated nickel foam into this mixed solution for impregnation, and the impregnation time is 30 minutes. After that, place the impregnated nickel foam on a porcelain ark and let it dry naturally. After the sample is dried, wash it repeatedly with deionized water and absolute ethanol. Subsequently, place the sample in a vacuum drying oven at 120 °C for drying, and nickel foam wrapped with amorphous nickel iron oxyhydroxide and nickel cobaltate is obtained. The characteristics and properties are similar to those of Example 1.

[0061] The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the described embodiments. Those skilled in the art can also make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A preparation method of a self-supporting amorphous nickel iron oxyhydroxide-coated nickel cobaltate heterojunction electrocatalytic composite material, characterized in that, It includes the following steps: A. Preparation of nickel cobalt oxide heterojunction Disperse 0.7 - 2.3 parts by weight of nickel chloride hexahydrate, 0.3 - 1.2 parts by weight of cobalt chloride hexahydrate, and 0.3 - 1.0 parts by weight of urea evenly in deionized water, and stir until a clear pink solution is formed; then, transfer the above solution to a stainless - steel hydrothermal reactor equipped with an inert lining, and vertically place the support carrier into the reactor; subsequently, keep it at 120 - 160 °C for 5 - 12 hours, after naturally cooling to room temperature, wash the support carrier with deionized water and absolute ethanol multiple times; then transfer it to a vacuum drying oven for overnight drying, and place the dried sample in a muffle furnace, and keep it at 300 - 450 °C for 2 - 5 hours; B. Amorphous nickel - iron oxyhydroxide - coated nickel cobalt oxide heterojunction Mix ferric chloride and nickel chloride in a molar ratio of 1:1 to prepare a mixed solution with a concentration of 50 mM; then, put the support carrier loaded with nickel cobalt oxide heterojunction prepared in step A into this mixed solution for impregnation for a certain time; after natural drying, wash it repeatedly with deionized water and absolute ethanol, and then place the sample in a vacuum drying oven at 60 - 120 °C for drying to obtain a self - supported electrocatalytic composite material NiCo2O4@a - NiFeO(OH) with amorphous nickel - iron oxyhydroxide - coated nickel cobalt oxide heterojunction.

2. The preparation method according to claim 1, wherein: Among them, In step A, the final concentration of nickel chloride hexahydrate is 0.023 - 0.038 g / mL, the final concentration of cobalt chloride hexahydrate is 0.01 - 0.02 g / mL, and the final concentration of urea is 0.01 - 0.017 g / mL.

3. The preparation method according to claim 1, wherein: Among them, The solution is stirred for 30 - 40 min to form a clear pink solution; the inert lining is selected from polytetrafluoroethylene lining; the support carrier is selected from nickel foam.

4. The preparation method according to claim 1, wherein: Among them, In step B, the impregnation time of the support carrier loaded with nickel cobalt oxide heterojunction in the mixed solution of ferric chloride and nickel chloride is 10 - 30 minutes; then the infiltrated nickel foam is left to dry naturally on a porcelain boat.

5. A self-supporting electrocatalytic composite material of amorphous nickel iron oxyhydroxide-wrapped nickel cobaltate heterojunction, characterized in that, Prepared by using the method according to any one of claims 1 - 4.

6. The electrocatalytic composite material according to claim 5, wherein In the material, nickel cobalt oxide forms a nano - needle support structure with a structure width of 180 - 220 nm, and the composite material is a two - dimensional nanosheet uniformly grown to wrap nickel cobalt oxide.

7. Use of the self - supported electrocatalytic composite material with amorphous nickel - iron oxyhydroxide - coated nickel cobalt oxide heterojunction according to claim 5 or 6 in the preparation of a water - electrolysis oxygen - evolution electrode.

8. A water electrolysis oxygen electrode, characterized in that, It includes a carrier and a catalyst material loaded thereon, wherein the catalyst material is a self - supported electrocatalytic composite material with amorphous nickel - iron oxyhydroxide - coated nickel cobalt oxide heterojunction prepared by using the method according to any one of claims 1 - 4.

9. A method for electrolyzing water, characterized in that: Use the water - electrolysis oxygen - evolution electrode according to claim 8 as the working electrode.

10. The method for electrolyzing water according to claim 9, wherein: Among them, The electrolyte is 1M KOH solution.

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