阅读说明：本技术 一种电解海水的镍铁析氧电化学催化剂及其制备方法和应用 (Nickel-iron oxygen evolution electrochemical catalyst for seawater electrolysis and preparation method and application thereof ) 是由 董国法 杜少武 谢锋炎 吴克琛 于 2021-02-20 设计创作，主要内容包括：本发明公开了一种电解海水的镍铁析氧电化学催化剂及其制备方法和应用,该催化剂以镍盐和铁盐为前驱体,以碳纤维布作为载体,在常压和低于100℃的条件下,通过液相反应,即可实现镍铁催化剂在碳布上的原位负载。所得催化剂对海水电化学析氧反应具备优良的催化活性,同时具备良好的催化稳定性,在100 mA cm～(-2)电流密度下连续电化学析氧83 h,过电位仅增加21 mV,优于目前报道的大多数海水析氧催化剂。这对未来利用海水获取氢能同时实现海水淡化具有十分重要的意义。该催化剂制备方法简单,所需原料来源丰富且成本较低,反应条件易于实现,符合工业化生产所要求的经济性原则,具备规模化生产的前景。(The invention discloses a nickel-iron oxygen evolution electrochemical catalyst for seawater electrolysis, and a preparation method and application thereof. The obtained catalyst has excellent catalytic activity on the electrochemical oxygen evolution reaction of seawater, and simultaneously has good catalytic stability at 100 mA cm ‑2 The overpotential is increased by only 21 mV after continuous electrochemical oxygen evolution for 83 h under current density, which is superior to most of seawater oxygen evolution catalysts reported at present. The method has very important significance for obtaining hydrogen energy by utilizing seawater and realizing seawater desalination in the future. The catalyst has the advantages of simple preparation method, abundant sources of required raw materials, low cost and reaction stripThe piece is easy to realize, accords with the economic principle required by industrial production, and has the prospect of large-scale production.)

1. A preparation method of a nickel-iron oxygen evolution electrochemical catalyst for seawater electrolysis is characterized by comprising the following steps: the method comprises the following steps:

pretreating carbon cloth: pretreating the carbon cloth with oxygen plasma;

preparing a precursor solution: weighing nickel salt, ferrous salt, urea and deionized water, and forming a uniform precursor solution by stirring and ultrasonic assistance;

and (3) placing the carbon cloth pretreated in the step (1) in the precursor solution in the step (2), heating to react, cooling to room temperature, taking out the carbon cloth after reaction, washing with deionized water, removing adsorbates on the surface, and drying to obtain the nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater.

2. The method for preparing a nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater according to claim 1, characterized in that: the power of the oxygen plasma treatment in the step (1) is 5-150W, and the time is 5-500 s.

3. The method for preparing a nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater according to claim 1, characterized in that: the dosage of the nickel salt in the step (2) is 0.1-25 mmol, the dosage of the ferrous salt is 0.5-50 mmol, the dosage of the urea is 5-100 mmol, the dosage of the deionized water is 30-200 ml, the stirring time is 30-80 min, and the ultrasonic treatment time is 10-60 min.

4. The method for preparing a nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater according to claim 3, characterized in that: the molar ratio of the nickel to the iron in the step (2) is 1: 0.25-4.

5. The method for preparing a nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater according to claim 4, characterized in that: a more preferred molar ratio of nickel to iron as described in step (2) is 3: 2.

6. The method for preparing a nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater according to claim 1, characterized in that: the heating reaction in the step (3) is specifically as follows: heating to 50-95 ℃ at a heating rate of 2-10 ℃/min, and keeping the temperature for 0.5-12 h.

7. A nickel-iron oxygen evolution electrochemical catalyst for electrolyzing seawater, prepared by the preparation method as claimed in any one of claims 1 to 6.

8. Use of the nickel iron oxygen evolution electrochemical catalyst for the electrolysis of seawater according to claim 7 in the electrolysis of seawater under alkaline body conditions.

Technical Field

The invention belongs to the field of electrochemical hydrogen production, and particularly relates to a nickel-iron oxygen evolution electrochemical catalyst for seawater electrolysis, and a preparation method and application thereof.

Background

At present, the energy crisis and the water resource crisis are two major problems which puzzle the future development of human beings. Fossil fuels such as coal, oil, and natural gas are non-renewable energy sources and are eventually exhausted, and development and utilization of these fossil energy sources have caused serious environmental problems. The development of green and environment-friendly clean fuel is the final strategy for solving the future energy crisis, hydrogen energy is one of the most promising clean fuels, and the hydrogen energy has the advantages of high energy density, rich raw material sources, various preparation methods, green and nontoxic combustion products and the like. Among a plurality of hydrogen production methods, the water electrolysis hydrogen production technology has the highest conversion efficiency and is suitable for large-scale production, the water is used as a raw material, the conversion of renewable energy sources such as solar energy, wind energy, tidal energy and the like into hydrogen energy can be realized through the water electrolysis technology, and the generated hydrogen can be stored as fuel. Compared with the traditional thermochemical hydrogen production method, the hydrogen production by electrolyzing water has the advantages of greenness, high efficiency, low cost, simple process, high hydrogen purity and the like. The hydrogen production by water electrolysis mainly comprises two electrode reaction processes of hydrogen production and oxygen production, which respectively correspond to an anode hydrogen evolution reaction and a cathode hydrogen evolution reaction. At present, the hydrogen production technology by water electrolysis still faces the technical problems of high overpotential, poor catalyst stability and the like, the high overpotential can cause higher voltage to be applied in the water electrolysis process, the consumption of electric energy is increased, the conversion efficiency of the electric energy in the water electrolysis process is further reduced, and the poor stability of the catalyst can also reduce the conversion efficiency of hydrogen energy.

The development of highly efficient electrode catalysts (comprising an anode catalyst and a cathode catalyst) is an important technical route to solve this problem. Among them, the development of an oxygen evolution catalyst is an important approach to lowering overpotential. Compounds of noble metals such as ruthenium and iridium have been used as commercial oxygen evolution catalysts because of their good oxygen evolution catalytic performance, but these noble metals are expensive and have a limited reserve on earth, and they cannot meet future large-scale demands. Therefore, a non-noble metal catalyst material with high efficiency and low price must be developed to obtain the oxygen evolution catalyst which can really meet the future requirement, which is also the important research field of the current electrolytic water oxygen evolution catalyst. At present, the research and development of non-noble metal oxygen evolution catalysts have been greatly advanced, but the oxygen evolution catalysts which can really meet the actual requirements are still limited, and the related research and development still face some technical problems, mainly as follows: 1. many oxygen evolution catalysts are synthesized ex situ and must be supported on a conductive substrate using a binder in order to be fabricated into an electrode. Although the use of the binder can effectively support the catalyst, the structure and the intrinsic performance of the catalyst are damaged to a great extent, the number of active sites is reduced, and the catalytic efficiency of the oxygen evolution catalyst is reduced. In addition, the amount of binder must also be optimized for optimal catalytic performance. This increases the production steps and the cost investment, which is disadvantageous for minimizing the manufacturing cost of the catalyst. 2. Many oxygen evolution catalysts prepared by in situ synthesis are prepared under high pressure critical conditions above 150 ℃, consume more energy than normal pressure synthesis conditions below 100 ℃, and the high pressure reaction also causes the risk factor to further increase. 3. Although most of oxygen evolution catalysts can show excellent oxygen evolution catalytic performance in a pure water solution system, the oxygen evolution catalysts are not suitable for a seawater system, because the application environments of the oxygen evolution catalysts and the seawater system are completely different, compared with a fresh water environment, the seawater system has more complex components and strong corrosivity, the requirements on catalyst materials are more severe, and the design of the catalyst materials is more challenging. Therefore, the development of a non-noble metal oxygen evolution catalyst applicable to a seawater system has very important significance for the development of hydrogen production technology and hydrogen energy industry.

The patent [ CN104659357A ] invents a supported nickel-iron composite hydroxide oxygen evolution electrode for alkaline water electrolysis and a preparation method thereof, but the preparation method of the material in the patent is complex, comprises the steps of physical mixing-rolling, heat treatment, in-situ deposition, metal current collector pressing and the like, and needs to use a binder, and the catalyst of the material has relatively high overpotential for water electrolysis catalysis. Patent [ CN108295855A ] reports a nickel-iron hydroxide composite material, in which a carbon cloth with polypyrrole nanowire arrays is firstly prepared by electrolysis in the first step, and a multi-stage carbon-based needle-like nanowire/needle array with the carbon cloth as a substrate is obtained by high-temperature heat treatment in the second step, but the preparation method is relatively complex, and the obtained iron hydroxide composite material has good catalytic activity for electrochemical oxygen evolution, but no research on the aspect of seawater electrolysis oxygen evolution is carried out. The patent [ CN111905744A ] also does not carry out the electro-catalytic performance research on the seawater oxygen evolution aspect of the obtained nickel-iron hydroxide composite material.

In summary, although several patents have reported the preparation method and electrocatalytic performance of the ferronickel catalyst material, the preparation method and catalytic oxygen evolution performance of the ferronickel catalyst still have room for further improvement. Compared with the nickel-iron electrochemical oxygen evolution catalyst reported in the patents, the preparation method disclosed by the invention does not need expensive preparation equipment and a complex preparation process, can effectively reduce the preparation cost, can simultaneously realize oxygen evolution in fresh water and seawater environments by using the prepared catalyst, has good catalytic activity and excellent catalytic stability, can realize long-time electrolysis under high current density in seawater, and has an important application prospect in the aspect of preparing oxygen by electrolyzing seawater.

Disclosure of Invention

In order to further improve the performance of the oxygen evolution catalyst, one of the objectives of the present invention is to solve the problem of binder usage by in situ synthesis. The nickel-iron catalyst loaded on the carbon cloth substrate is obtained by taking carbon cloth as the substrate and nickel salt and ferric salt as main initial reactants through low-temperature normal-pressure reaction. The catalyst is fixedly supported on the surface of the carbon fiber in a three-dimensional multi-layer network structure, so that the in-situ growth of the nickel-iron composite material on the carbon cloth is realized, and the large-area high-quality loading of the catalyst can be realized.

The invention also aims to reduce the preparation cost of the catalyst and improve the safety of the preparation process. Compared with noble metals such as ruthenium, iridium and the like, the nickel salt, the iron salt and the carbon cloth belong to basic industrial raw materials, and have low cost and rich sources. In addition, the synthesis process is carried out under the conditions of normal pressure and the temperature lower than 100 ℃, and the reaction equipment mainly comprises a plasma cleaning machine, a heating table and a glass reaction bottle. The reaction conditions are easy to reach, and high temperature and high pressure are not needed; the reaction process is simple to operate, safe and controllable, no harmful gas is generated, waste generated by reaction can be collected in a centralized manner, harmless treatment is facilitated, and pollution to the environment is eliminated.

The invention also aims to realize high-efficiency electrochemical oxygen evolution in seawater. In an alkaline seawater solution system, the obtained nickel-iron catalyst is at 10 mA cm^-2、100 mA cm^-2、200 mA cm^-2Under the current density, the overpotentials required for the oxygen evolution reaction are 235 mV, 289 mV and 314 mV respectively at 100 mA cm^-2The electrolytic potential is only increased by 21 mV after the seawater electrochemical oxygen evolution reaction is driven for 83 hours under the current density, the obtained ferronickel oxygen evolution catalyst has good catalytic activity and catalytic stability for the oxygen evolution reaction in a seawater solution system, and the catalytic performance is superior to that of most currently reported seawater electrochemical oxygen evolution catalysts.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of a nickel-iron oxygen evolution electrochemical catalyst for seawater electrolysis comprises the following steps: (1) pretreatment of commercial carbon cloth: firstly, a commercial carbon cloth with the area of 3 multiplied by 0.8 cm is pretreated for a certain time by oxygen plasma under certain power, so that the surface hydrophilic performance of the commercial carbon cloth is enhanced. (2) Preparation of a reaction precursor solution: accurately weighing nickel salt, ferrous salt and urea by an electronic balance, placing the nickel salt, ferrous salt and urea into a reaction bottle, adding secondary deionized water, and forming uniform mixed liquid under the assistance of stirring and ultrasound. (3) Placing the carbon cloth pretreated in the step (1) in the reaction mixed liquid in the step (2), heating at a certain heating rate, and carrying out a constant-temperature chemical reaction at a temperature lower than 100 ℃. And after the reaction is finished, naturally cooling to room temperature, taking out the carbon cloth after the reaction, washing with deionized water, removing adsorbates on the surface, and placing in a drying oven for drying for later use to obtain the ferronickel oxygen evolution electrochemical catalyst for electrolyzing seawater.

Further, the power of the step (1) is 5-150W, and the certain time is 5-500 s.

Further, the dosage of the nickel salt in the step (2) is 0.1-25 mmol, the dosage of the ferrous salt is 0.5-50 mmol, the dosage of the urea is 5-100 mmol, the dosage of the secondary deionized water is 30-200 ml, the stirring time is 30-80 min, and the ultrasonic treatment time is 10-60 min; more preferably, the molar ratio of nickel to iron in step (2) is 1:0.25 to 4, and even more preferably, the molar ratio of nickel to iron in step (2) is 3: 2.

Further, the certain heating rate in the step (3) is 2-10 ℃ for min^-1The constant temperature is 50-95 ℃ and the period of time is 0.5-12 h.

The nickel-iron oxygen evolution catalyst has the following catalytic performance in seawater electrolysis oxygen evolution: the nickel-iron oxygen evolution catalyst prepared by the method is packaged into an electrocatalytic electrode, and the catalytic performance of the nickel-iron oxygen evolution catalyst in the aspect of electrocatalytic oxygen evolution in a water solution reducing system is verified by adopting an electrochemical method, and the method comprises the following steps: 1) packaging the nickel-iron oxygen evolution catalyst by using silica gel resin to prepare a working electrode for testing the electro-catalysis oxygen evolution performance; 2) a traditional three-electrode test system is adopted to test various performances of the catalyst in catalyzing and oxygen evolution: the carbon cloth loaded with the nickel-iron oxygen evolution catalyst is used as a working electrode, the graphite electrode is used as a counter electrode, the saturated calomel electrode is used as a reference electrode, and the fresh water or seawater solution system is used as electrolyte, so that the catalytic performance of the carbon cloth on the electrolysis of fresh water or seawater oxygen evolution is tested. The test result can directly explain the main electrocatalytic index and the overall performance of the ferronickel oxygen evolution catalyst.

The encapsulation of step 1) serves to fix the area of the electrodes in order to quantify the relevant electrocatalytic performance indicators.

The fresh water or seawater solution system in the step 2) is KOH solution prepared by fresh water or seawater. The test process mainly adopts cyclic voltammetry and chronoamperometry. Test results of electrochemical experiments internal resistance subtraction and potential conversion with respect to reversible hydrogen electrode have been performed.

The invention has the advantages that:

(1) provides a novel preparation method of a seawater oxygen evolution catalyst. The method comprises the following steps of firstly generating hydrophilic groups on the surface of the carbon cloth through a plasma treatment technology, changing the surface of the hydrophobic carbon cloth into a hydrophilic surface, and controlling the power and the treatment time of a plasma generator to adjust the strength of the hydrophilic property of the surface of the carbon cloth. And secondly, directly immersing the carbon cloth into the reaction solution, and performing normal-pressure chemical deposition reaction at the temperature of below 100 ℃ to realize the growth of the nickel-iron catalyst on the surface of the carbon cloth, wherein the reaction process is simple, efficient, safe and nontoxic. By controlling the temperature and time of the deposition reaction and the composition of the precursor solution, the composition of the nickel-iron catalyst and the loading capacity of the nickel-iron catalyst on the surface of the carbon cloth can be controlled.

(2) The prepared nickel-iron catalyst has good tolerance to seawater corrosion, and simultaneously has good oxygen evolution activity and stability in a KOH alkaline seawater solution system; the growth of the NiFe catalyst on the surface of the carbon cloth is a step-by-step deposition process, and if a catalyst with uniform Ni and Fe contents is to be formed, the deposition rates of nickel ions and iron ions must be controlled to achieve simultaneous deposition. At the same pH, Fe³⁺Deposition rate of (2) is much greater than that of Ni²⁺Deposition rate of (1), and Fe²⁺And Ni²⁺The deposition rates of (a) are very close, so the method selects ferrous ions as the iron source based on the uniformity of the composition and morphology of the product.

(3) If the carbon cloth surface has stronger hydrophobicity, it is not favorable to load other compounds on the surface^[1]. Reference reports^[2,3,4]In order to enhance the hydrophilic property, the carbon cloth is generally subjected to surface oxidation treatment by a strongly oxidizing acid such as nitric acid, sulfuric acid, etc., but this method is environmentally polluting and time-consuming. The method adopts the oxygen plasma treatment method, can effectively enhance the hydrophilicity of the surface of the carbon cloth, and has simple and efficient treatment process, rapidness, environmental protection and high economical efficiency compared with the traditional acid oxidation treatment method.

Drawings

FIG. 1 is a photoelectron spectrum of the ferronickel oxygen evolution catalyst prepared in example 7, which shows that the catalyst contains Ni, Fe, O elements, and the signal of C element comes from a carbon cloth substrate;

fig. 2 is a scanning electron microscope image of the ferronickel oxygen evolution catalyst prepared in example 7, it can be observed that the ferronickel catalyst completely wraps carbon fibers in the carbon cloth with a high loading amount, and the ferronickel catalyst is in a lamellar structure, and abundant micro-nano pores are formed between lamellae, which is very beneficial to improving the electrocatalytic oxygen evolution performance of the ferronickel catalyst;

FIG. 3 is a plot of the seawater oxygen evolution electrochemical activity of the nickel iron oxygen evolution catalyst prepared in example 7, with increasing applied potential, the amount of oxygen generated on the electrode surface gradually increases, causing greater disturbance to the mass transfer and electron transfer at the electrode interface, resulting in fluctuations in the cyclic voltammetry curve after 1.52V rather than smoothing the curve before;

FIG. 4 is a plot of the nickel iron oxygen evolution catalyst prepared in example 7 at 100 mA cm^-2Under current density, the pH value of a seawater system is about 13.5, the test time is 83 hours, and the electrolyte is KOH;

fig. 5 is a scanning electron microscope image of the ferronickel oxygen evolution catalyst prepared in example 8, wherein the precursor solution NiFe atomic ratio: (a) 10:0, (b) 8:2, (c) 6:4, (d) 5:5, (e) 4:6, (f) 2:8, (g) 0:10, with 10 μm scale in the figure. According to SEM images, the atomic ratio of NiFe contained in the precursor solution has great influence on the structure and the appearance of the ferronickel oxygen evolution catalyst. The precursor solution only contains Ni²⁺Only a thin layer of nickel compound is formed on the surface of the carbon fiber, and the precursor solution contains 20 percent of Fe²⁺Begins to form a three-dimensional network structure with Fe²⁺The content is increased from 20% to 80%, the basic flaky units in the three-dimensional network structure start to grow gradually and gradually change from flaky to large petal-shaped, the pore size among the flaky units is also gradually increased, and the precursor solution only contains Fe²⁺In this case, a three-dimensional network structure cannot be formed, and only one layer of iron compound particles is formed on the surface. Therefore, the atomic ratio of NiFe contained in the precursor solution has decisive influence on the appearance of the ferronickel oxygen evolution catalyst, and the change of the appearance further has decisive influence on the appearance of the ferronickel oxygen evolution catalystThe catalytic performance of the nickel-iron oxygen evolution catalyst has a deep influence;

FIG. 6 shows the electrocatalytic activity of the nickel-iron oxygen evolution catalyst prepared in example 8 in fresh water with a medium of 1M KOH in deionized water. The NiFe ratio of the precursor solution is 10:0, 8:2, 6:4, 5:5, 4:6, 2:8 and 0: 10. The figure illustrates that the NiFe ratio of the precursor solution directly determines the electrocatalytic activity of the ferronickel oxygen evolution catalyst. The addition of the iron element can effectively improve the electrocatalytic activity of the ferronickel oxygen evolution catalyst, but the addition of excessive iron element can reduce the electrocatalytic activity, and when the NiFe ratio of the precursor solution is 6:4, the obtained ferronickel oxygen evolution catalyst shows the optimal activity;

FIG. 7 shows the electrocatalytic activity of the nickel-iron oxygen evolution catalyst prepared in example 9 in fresh water with a medium of 1M KOH in deionized water. The proportion of the precursor solution NiFe is 6:4, and the reaction time is 0.5 h, 1 h, 2 h, 4 h and 6 h. This figure illustrates the effect of reaction time on the electrocatalytic activity of the ferronickel oxygen evolution catalyst. From 0.5 h to 4 h, the electrocatalytic activity is gradually enhanced along with the increase of the growth time, and when the growth time is 6 h, the electrocatalytic activity begins to show a descending trend, so that the optimal reaction time is determined to be 4 h.

Detailed Description

The present invention will be further described with reference to the following examples and drawings, but the scope of the invention should not be limited thereto.

Example 1, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 10W for 30 s to obtain carbon cloth a. Mixing 4 mmol of nickel chloride hexahydrate and 6 mmol of ferrous sulfate heptahydrate according to the mass ratio of 2:3, and diluting in deionized water to obtain a dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 60 ℃ at the heating rate of 2 ℃/min, reacting for 2 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 2, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 25W for 100 s to give carbon cloth a. Mixing nickel chloride hexahydrate and ferrous sulfate heptahydrate according to the mass ratio of 2:3, and diluting the mixture in deionized water to obtain dispersion liquid B. Weighing 10 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid B, heating to 60 ℃ at the heating rate of 2 ℃/min, reacting for 4 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 3, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 10W for 500 s to obtain carbon cloth a. Mixing 4 mmol of nickel chloride hexahydrate and 6 mmol of ferrous sulfate heptahydrate according to the mass ratio of 2:3, and diluting in deionized water to obtain a dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 70 ℃ at the heating rate of 2 ℃/min, reacting for 2 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 4, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 50W for 300 s to give carbon cloth a. Mixing 2 mmol of nickel chloride hexahydrate and 8 mmol of ferrous sulfate heptahydrate according to the mass ratio of 1:4, and diluting in deionized water to obtain a dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 60 ℃ at the heating rate of 4 ℃/min, reacting for 4 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 5, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 150W for 60 s to obtain carbon cloth a. Mixing 4 mmol of nickel chloride hexahydrate and 6 mmol of ferrous sulfate heptahydrate according to the mass ratio of 3:2, and diluting in deionized water to obtain a dispersion liquid A. Weighing 20 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 80 ℃ at the heating rate of 4 ℃/min, reacting for 0.5 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 6, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 100W for 30 s to obtain carbon cloth a. 5 mmol of nickel chloride hexahydrate and 5 mmol of ferrous sulfate heptahydrate are mixed according to the mass ratio of 1:1 and diluted in deionized water to obtain dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 95 ℃ at the heating rate of 4 ℃/min, reacting for 1 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 7, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 10W for 30 s to obtain carbon cloth a. Mixing 6 mmol of nickel chloride hexahydrate and 4 mmol of ferrous sulfate heptahydrate according to the mass ratio of 3:1, and diluting in deionized water to obtain a dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 60 ℃ at the heating rate of 2 ℃/min, reacting for 12 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying box.

Example 8, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 10W for 30 s to obtain carbon cloth a. Mixing nickel chloride hexahydrate and ferrous sulfate heptahydrate according to the mass ratio of 10:0 or 8:2 or 6:4 or 5:5 or 4:6 or 2:8 or 0:10, and diluting in deionized water to obtain a dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 90 ℃ at the speed of 5 ℃/min, reacting for 4 h at constant temperature, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying oven to obtain the nickel-iron oxygen evolution catalyst with different NiFe ratios.

Example 9, in situ preparation of ferronickel oxygen evolution catalyst: a commercial carbon cloth was treated in an oxygen plasma at a power of 10W for 30 s to obtain carbon cloth a. Mixing nickel chloride hexahydrate and ferrous sulfate heptahydrate according to the mass ratio of 6:4, and diluting the mixture in deionized water to obtain dispersion liquid B. Weighing 5 mmol of urea solid, dispersing in the dispersion liquid B of nickel chloride hexahydrate and ferrous sulfate heptahydrate, fully stirring for 30 min, and performing ultrasonic treatment for 30 min to completely dissolve the solid to obtain a dispersion liquid C. Immersing the A into the dispersion liquid C, heating to 90 ℃ at the heating rate of 5 ℃/min, reacting at constant temperature for 0.5 or 1 or 2 or 4 or 6 h, and naturally cooling to room temperature. And taking out the product, washing the product with deionized water, and drying the product in a drying oven to obtain the ferronickel oxygen evolution catalyst with different reaction times.

And (3) performance testing: the nickel-iron oxygen evolution catalyst prepared by the method is packaged into an electrocatalytic electrode, and the catalytic performance of the nickel-iron oxygen evolution catalyst in the aspect of electrocatalytic oxygen evolution in a water solution reducing system is verified by adopting an electrochemical method, and the method comprises the following steps: 1) packaging the nickel-iron oxygen evolution catalyst by using silica gel resin to prepare a working electrode for testing the electro-catalysis oxygen evolution performance; 2) a traditional three-electrode test system is adopted to test various performances of the catalyst in catalyzing and oxygen evolution: the carbon cloth loaded with the nickel-iron oxygen evolution catalyst is used as a working electrode, the graphite electrode is used as a counter electrode, the saturated calomel electrode is used as a reference electrode, and the KOH seawater solution system is used as electrolyte, so that the catalytic performance of the carbon cloth on the electrolysis of fresh water or seawater oxygen evolution is tested. The test result can directly explain the main electrocatalytic index and the overall performance of the ferronickel oxygen evolution catalyst.

The encapsulation of step 1) serves to fix the area of the electrodes in order to quantify the relevant electrocatalytic performance indicators.

The fresh water or seawater solution system in the step 2) is KOH solution prepared by fresh water or seawater. The test process mainly adopts cyclic voltammetry and chronoamperometry. Test results of electrochemical experiments internal resistance subtraction and potential conversion with respect to reversible hydrogen electrode have been performed.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.