Fe-doped NiO electrolyzed water oxygen evolution catalyst rich in oxygen vacancies as well as preparation method and application of Fe-doped NiO electrolyzed water oxygen evolution catalyst

Abstract

The invention discloses a Fe-doped NiO electrolyzed water oxygen evolution catalyst rich in oxygen vacancies as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out acidification pretreatment on a nickel-based substrate; dissolving a nickel salt, an ammonium salt and urea in a solvent, adding the pretreated nickel-based substrate, and carrying out a hydrothermal reaction to form a sheet-shaped nano array structure; the NiO precursor is subjected to annealing treatment, inert gas is introduced to evacuate oxygen, the temperature is increased to the annealing temperature under the protection of the inert gas, then heat preservation is conducted for 1-3 h, when the heat preservation stage starts, argon and hydrogen mixed gas is switched to be kept for 10-30 min, and then the inert gas is switched back and continues till the annealing treatment is finished; soaking the NiOx catalyst precursor in an iron source solution, and carrying out air drying treatment; through the synergistic effect of Fe doping and oxygen vacancies, in the electrochemical oxygen evolution reaction in the catalytic alkaline environment, good catalytic activity and stability are shown, and good industrial application prospects and commercial value are achieved.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and more specifically, to an oxygen-vacancy-rich Fe-doped NiO electrolysis oxygen evolution catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, hailed as one of the most promising energy sources for future human societal and economic development, is considered the best clean energy source in the world. Water electrolysis is the most convenient method for producing clean, zero-carbon-emission hydrogen. However, the oxygen evolution reaction (OER) in alkaline media involves a four-electron coupling step, resulting in slow reaction kinetics that severely limit the energy conversion efficiency of water electrolysis. Therefore, highly active and stable electrocatalysts, especially at high current densities, remain a significant challenge for industrial applications. High price, scarcity, and poor durability of commercially available Pt-based catalysts have severely hampered their widespread and practical industrial application. In recent years, various NiFe-based electrocatalysts have become an effective component in accelerating the slow OER kinetics under alkaline conditions. However, achieving high-activity, low-cost water electrolysis for hydrogen production by controlling the catalyst crystal structure remains a significant challenge. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art and provide a hydrothermal in-situ grown Fe-doped NiO catalyst for water electrolysis with oxygen-rich vacancies, its preparation method, and its application. NiO can be prepared using a simple method. x The Fe catalyst electrode uses metallic nickel as a conductive substrate, and the active catalyst layer is prepared by hydrothermal treatment, high-temperature annealing, and room-temperature immersion. This catalyst exhibits good catalytic activity and stability in the electrochemical oxygen evolution reaction under alkaline conditions using a conventional three-electrode system, demonstrating promising industrial application prospects and commercial value.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing an oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst includes the following steps: S1. The nickel-based substrate is subjected to acidification pretreatment to obtain the pretreated nickel-based substrate; S2. Dissolve nickel salt, ammonium salt and urea in a solvent to obtain a precursor solution, add the pretreated nickel-based substrate and carry out a hydrothermal reaction, then wash and dry to form a sheet-like nanoarray structure on the surface of the nickel-based substrate to obtain the NiO precursor. S3. Anneal the NiO precursor to obtain NiO. xCatalyst precursor; wherein the annealing treatment includes: introducing an inert gas to purge oxygen from the reaction system, and heating to the annealing temperature under the protection of the inert gas and holding at that temperature for 1-3 hours; at the beginning of the holding stage, switching the inert gas to an argon-hydrogen mixture and maintaining it for 10-30 minutes, and then switching the argon-hydrogen mixture back to the inert gas and continuing until the annealing treatment is completed; wherein the annealing temperature is 200-600℃; S4, the NiO x The catalyst precursor was immersed in an iron source solution and then air-dried to obtain the oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst (NiO). x -Fe catalyst).

[0005] Optionally, in step S1, the acidification pretreatment is as follows: the nickel-based substrate is placed in an acid solution for ultrasonic cleaning for 10-30 minutes, and then the nickel-based substrate is placed in deionized water for ultrasonic cleaning for 10-30 minutes.

[0006] Optionally, in step S1, the soaking time is preferably any value among 10 min, 15 min, 20 min, 25 min, and 30 min, or a range between any two of the above.

[0007] Optionally, in step S1, the acid solution is at least one of hydrochloric acid solution, nitric acid solution, and sulfuric acid solution.

[0008] Optionally, in step S1, the concentration of the acid solution is 10wt% to 50wt%; preferably, the concentration of the acid solution is selected from any value of 10wt%, 20wt%, 30wt%, 40wt%, 50wt% or a range between any two of the above.

[0009] Optionally, in step S1, the nickel-based substrate is selected from at least one of nickel foil, nickel foam, and nickel felt; preferably, nickel foam provides abundant pore structure for the catalyst, effectively improving mass transport during the catalytic process; the large specific surface area of ​​the nickel foam substrate provides abundant sites for in-situ growth of sheet-like structures, and its high conductivity promotes charge transfer, effectively promoting the enhancement of catalytic activity.

[0010] Optionally, in step S2, the nickel salt is selected from at least one of nickel sulfate, nickel nitrate, and nickel chloride.

[0011] Optionally, in step S2, the ammonium salt is selected from at least one of ammonium fluoride, ammonium chloride, and ammonium sulfate.

[0012] Optionally, in step S2, the concentration of the nickel salt in the precursor solution is 0.01~0.1 mol / L. Preferably, the concentration of the nickel salt in the precursor solution is any value selected from 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, and 0.1 mol / L, or a range between any two of the above.

[0013] Optionally, in step S2, the concentration of the ammonium salt in the precursor solution is 0.1~0.5 mol / L; preferably, the concentration of the ammonium salt in the precursor solution is any value among 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, and 0.5 mol / L, or a range between any two of the above.

[0014] Optionally, in step S2, the concentration of urea in the precursor solution is 0.05~0.5 mol / L; preferably, the concentration of urea in the precursor solution is any value among 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.20 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, and 0.5 mol / L, or a range between any two of the above.

[0015] Optionally, the molar amount of the precursor solution is expressed in terms of the molar amount of metal ions.

[0016] Optionally, in step S2, the temperature of the hydrothermal reaction is 100~150℃, preferably any value among 100℃, 110℃, 120℃, 130℃, 140℃, and 150℃, or a range between any two of the above.

[0017] Optionally, in step S2, the hydrothermal reaction time is 5 to 10 hours, preferably any value among 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, and 10 hours, or a range between any two of the above.

[0018] Optionally, in step S2, the drying temperature is 40~80℃ and the drying time is 10~24h.

[0019] Optionally, in step S2, the washing solution used for washing is selected from at least one of ultrapure water and anhydrous ethanol.

[0020] Optionally, the reaction system in step S2 is carried out in a hydrothermal reactor.

[0021] Optionally, in step S3, the annealing temperature is preferably any value among 200℃, 300℃, 400℃, 500℃, and 600℃, or a range between any two of the above; the annealing time is 1~3h, preferably any value among 1h, 1.5h, 2h, 2.5h, and 3h, or a range between any two of the above; and the heating rate of the annealing process is 2~10℃ / min.

[0022] Optionally, in step S3, the volume ratio of hydrogen in the argon-hydrogen mixture is 5% to 10%.

[0023] Optionally, in step S3, the inert gas is either argon or nitrogen.

[0024] Optionally, in step S3, the flow rate of the argon-hydrogen mixture is 10~30 ml / min.

[0025] Optionally, in step S3, the flow rate of the inert gas is 50~100 ml / min.

[0026] Optionally, in step S4, the soaking time is 0.5 to 2 hours; the soaking temperature is room temperature.

[0027] Optionally, in step S4, the iron source solution is an ethanol solution of iron salt.

[0028] Optionally, in step S4, the iron salt in the ethanol solution of the iron salt is selected from at least one of ferric sulfate, ferric nitrate, and ferric chloride.

[0029] Optionally, in step S4, the concentration of the ethanol solution of the iron salt is 0.01~0.1 mol / L; preferably, the concentration of the ethanol solution of the iron salt is any value among 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, and 0.10 mol / L, or a range between any two of the above.

[0030] The present invention also discloses an oxygen-vacancy-rich Fe-doped NiO electrolysis oxygen evolution catalyst prepared by the preparation method described above.

[0031] Optionally, the catalyst is NiO. x -Fe catalyst, where x represents the oxygen vacancy content.

[0032] The present invention also discloses the application of the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies prepared by the above preparation method in the electrochemical oxygen evolution reaction in an alkaline environment.

[0033] Specifically, the NiO of the present invention x The Fe catalyst is a sheet-like nanoarray structure grown in situ on a nickel foam substrate via a hydrothermal method, creating a high density of active sites. During the annealing stage, oxygen is first purged using an inert gas, then the temperature is raised to the annealing temperature. When the temperature reaches the set value, the atmosphere is switched to an argon-hydrogen mixture and maintained for a certain time. Subsequently, the atmosphere is adjusted back to an inert gas to stabilize the structure. This controllable atmosphere regulation strategy effectively introduces a defect structure rich in oxygen vacancies. Furthermore, the synergistic effect of Fe doping and oxygen vacancies gives it high catalytic efficiency for the oxygen evolution reaction, reaching 10 mA / cm². 2 The overpotential at the given current density is 201 mV; meanwhile, only an overpotential of 283 mV is required to achieve 1 A / cm. 2 The current density is [not specified]. This catalyst can be used for oxygen production through water electrolysis. It exhibits high catalytic activity and high stability under alkaline conditions, and can improve the oxygen evolution efficiency of water electrolysis, showing potential to replace precious metal catalysts.

[0034] Furthermore, this invention optimizes the catalyst structure and performance by adjusting reaction conditions to control the oxygen vacancy content. When applied to the electrochemical oxygen evolution reaction in an alkaline environment, it exhibits good catalytic activity and stability, demonstrating promising industrial application prospects and commercial value.

[0035] Furthermore, the preparation method of the present invention is simple to operate, has mild reaction conditions, and requires simple equipment. It is operable and reproducible, and has good prospects for industrial application and commercial value.

[0036] In summary, this catalyst uses nickel foam as a substrate and grows sheet-like nanoarrays via hydrothermal method to provide high-density active sites. Then, through annealing and atmosphere control, oxygen vacancy defects are introduced into the crystal interior of the nanosheets. Finally, the electronic structure is fine-tuned by surface doping with Fe elements through immersion method. Performance optimization is achieved through the synergistic regulation of Fe doping and oxygen vacancies, effectively reducing the energy barrier for water electrolysis and obtaining an oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst.

[0037] Implementing the embodiments of the present invention will have the following beneficial effects: 1) The controllable preparation of NiO provided in this application x The oxygen evolution activity of the -Fe catalyst can be tuned by using different annealing atmospheres.

[0038] 2) The preparation method provided in this application obtains a highly active and stable electrode system by changing parameters such as the concentration of the reaction solution, reaction temperature, reaction time, annealing atmosphere, and annealing time, thereby meeting different requirements for catalytic performance.

[0039] 3) The integral electrode provided in this application is preferably based on nickel foam, which provides a rich pore structure for the catalyst and effectively enhances the mass transport in the catalytic process; the large specific surface area of ​​the nickel foam substrate provides abundant sites for in-situ growth of sheet-like structures, and its high conductivity promotes charge transfer, effectively enhancing catalytic activity.

[0040] 4) The preparation method provided in this application facilitates a tighter bond between the catalyst and the conductive support, thereby improving its charge transport characteristics and mechanical stability. This method can effectively control the oxygen vacancy concentration in the catalyst, regulate the crystal structure, promote oxygen evolution performance, and effectively reduce the cost of alkaline water electrolysis. Attached Figure Description

[0041] Figure 1 The NiO prepared in Example 1 of this application x - SEM images of Fe at different magnifications.

[0042] Figure 2 The images shown are TEM images at different magnifications, XPS analysis images of the O 2p orbitals, and EPR test images of the sample in Example 1 of this application, to demonstrate the successful introduction of oxygen vacancies.

[0043] Figure 3 This is a TEM elemental distribution map of the sample in Example 1 of this application.

[0044] Figure 4 This is a graph showing the oxygen evolution activity of nickel foam samples from Examples 1-3 and Comparative Example 1 in alkaline electrolyte. The horizontal axis represents the standard hydrogen electrode voltage (V vs RHE), and the vertical axis represents the current density (mA / cm²). 2 ).

[0045] Figure 5 The image shows the constant current Vt curve of the sample in Example 1 of this application in a 1 mol / L KOH electrolyte solution. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0047] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0048] This application uses a Gemini SEM 300 scanning electron microscope to measure the microstructure of the active material in the catalyst.

[0049] The lattice spacing of the active material in the catalyst was measured using a JEM-2100F transmission electron microscope.

[0050] The oxygen evolution performance was characterized using a KOSTER electrochemical workstation. The oxygen evolution activity of the prepared catalyst was tested by measuring the electrochemical polarization curve and the galvanostatic curve.

[0051] Example 1 The preparation method of the Fe-doped NiO electrolysis oxygen evolution catalyst rich in oxygen vacancies in this embodiment includes the following steps: Step 1: Using commercially available nickel foam (NF, 2.5 × 3 cm) 2 Using NF as a substrate, it was ultrasonically cleaned for 15 min each with 11 wt% HCl solution and deionized water, and then dried to obtain pretreated NF (pretreated nickel foam).

[0052] Step 2: Weigh 4.5 g urea, 1.3862 g ammonium fluoride, and 4.3665 g nickel nitrate hexahydrate, dissolve them in 175 ml of water and stir for 10 min until completely dissolved. Take 35 ml of the above precursor solution and place it in a 50 ml polytetrafluoroethylene-lined hydrothermal reactor. Add the pretreated NF and react at 120℃ for 6 h. After the hydrothermal reactor has completely cooled, remove the nickel foam and rinse it thoroughly with a large amount of ultrapure water and anhydrous ethanol. Then, dry it at 60℃ for 12 h to obtain NiO precursor 1.

[0053] Step 3: Place the NiO precursor 1 from Step 2 into a tube furnace. Fill the furnace with high-purity argon as a protective gas, continuously pumping it at a flow rate of 100 ml / min for 40 minutes to purge the oxygen from the furnace. After purging, adjust the flow rate to 60 ml / min and raise the temperature to 400℃ at a rate of 5℃ / min, maintaining this temperature for 2 hours. When the temperature reaches 400℃, adjust the atmosphere to a 10% argon-hydrogen mixture, adjusting the flow rate to 15 ml / min and maintaining this for 10 minutes. After the reaction, adjust the atmosphere to a high-purity argon flow rate of 60 ml / min, allow the reaction to complete, and then allow the sample to cool naturally before removing it to obtain NiO. x Catalyst precursor 2.

[0054] Step 4: Take 1*1.5 cm 2 Precursor 2 was immersed in a 0.05 mol / L anhydrous ethanol solution of ferric nitrate for 1 h at room temperature. After immersion, the nickel foam was removed and air-dried to obtain the final catalyst NiOx-Fe.

[0055] like Figure 1 As shown, the SEM image of the sample prepared in Example 1 shows that a sheet-like nanoarray structure was successfully grown on a nickel foam substrate.

[0056] like Figure 2As shown, TEM images at different magnifications, XPS analysis of the O 2p orbitals, and EPR test images of the samples in Example 1 are used to demonstrate the successful introduction of oxygen vacancies and the high concentration of oxygen vacancies.

[0057] like Figure 3 As shown, based on the TEM elemental distribution map of the sample in Example 1, the presence of Fe in NiO is illustrated. x The uniform distribution within the matrix indicates the formation of a stable doped structure.

[0058] Example 2 Step 1: Using commercially available nickel foam (NF, 2.5 × 3 cm) 2 Using NF as a substrate, it was ultrasonically cleaned for 15 min each with 11 wt% HCl solution and deionized water, and then dried to obtain pretreated NF (pretreated nickel foam).

[0059] Step 2: Weigh 4.5 g urea, 1.3862 g ammonium fluoride, and 4.3665 g nickel nitrate hexahydrate, dissolve them in 175 ml of water and stir for 10 min until completely dissolved. Take 35 ml of the above precursor solution and place it in a 50 ml polytetrafluoroethylene-lined hydrothermal reactor. Add the pretreated NF and react at 120℃ for 6 h. After the hydrothermal reactor has completely cooled, remove the nickel foam and rinse it thoroughly with a large amount of ultrapure water and anhydrous ethanol. Dry it at 60℃ for 12 h to obtain NiO precursor 1.

[0060] Step 3: Place the NiO precursor 1 from Step 2 into a tube furnace. Fill the furnace with high-purity argon as a protective gas, continuously pumping it at a flow rate of 100 ml / min for 40 minutes to purge the oxygen from the furnace. After purging, adjust the flow rate to 60 ml / min and raise the temperature to 400℃ at a rate of 5℃ / min, maintaining this temperature for 2 hours. When the temperature reaches 400℃, adjust the atmosphere to a 10% argon-hydrogen mixture, adjusting the flow rate to 15 ml / min and maintaining this for 20 minutes. After the reaction, adjust the atmosphere to a high-purity argon flow rate of 60 ml / min, allow the reaction to complete, and then allow the sample to cool naturally before removing it to obtain NiO. x Precursor 2.

[0061] Step 4: Take 1*1.5 cm 2 Precursor 2 was immersed in a 0.05 mol / L anhydrous ethanol solution of ferric nitrate at room temperature for 1 h. After immersion, the nickel foam was removed and air-dried to obtain the final catalyst NiOx-Fe-20.

[0062] Example 3 Step 1: Using commercially available nickel foam (NF, 2.5 × 3 cm) 2Using NF as a substrate, it was ultrasonically cleaned for 15 min each with 11 wt% HCl solution and deionized water, and then dried to obtain pretreated NF (pretreated nickel foam).

[0063] Step 2: Weigh 4.5 g urea, 1.3862 g ammonium fluoride, and 4.3665 g nickel nitrate hexahydrate, dissolve them in 175 ml of water and stir for 10 min until completely dissolved. Take 35 ml of the above precursor solution and place it in a 50 ml polytetrafluoroethylene-lined hydrothermal reactor. Add the pretreated NF and react at 120℃ for 6 h. After the hydrothermal reactor has completely cooled, remove the nickel foam and rinse it thoroughly with a large amount of ultrapure water and anhydrous ethanol. Then, dry it at 60℃ for 12 h to obtain NiO precursor 1.

[0064] Step 3: Place the NiO precursor 1 from Step 2 into a tube furnace. Fill the furnace with high-purity argon as a protective gas, continuously pumping it at a flow rate of 100 ml / min for 40 min to purge the oxygen from the furnace. After purging, adjust the flow rate to 60 ml / min and raise the temperature to 400℃ at a rate of 5℃ / min, maintaining this temperature for 2 h. When the temperature reaches 400℃, adjust the atmosphere to a 10% argon-hydrogen mixture, adjusting the flow rate to 15 ml / min and maintaining this for 30 min. After the reaction, adjust the atmosphere to a high-purity argon flow rate of 60 ml / min, allow the reaction to complete, and then allow the sample to cool naturally before removing it to obtain NiO. x Catalyst precursor 2.

[0065] Step 4: Take 1*1.5 cm 2 Precursor 2 was immersed in a 0.05 mol / L anhydrous ethanol solution of ferric nitrate at room temperature for 1 hour. After immersion, the nickel foam was removed and air-dried to obtain the final catalyst NiOx-Fe-30.

[0066] Comparative Example 1 The only difference between this comparative example and Example 1 is that the annealing atmosphere in step 3 is only air. Step 1: Using commercially available nickel foam (NF, 2.5 × 3 cm) 2Using urea as a substrate, the nickel foam was ultrasonically cleaned sequentially with 11 wt% HCl solution and deionized water for 15 min each, and then dried to obtain pretreated NF (pretreated nickel foam). Step 2: Weigh 4.5 g urea, 1.3862 g ammonium fluoride, and 4.3665 g nickel nitrate hexahydrate, dissolve them in 175 ml water and stir for 10 min until completely dissolved. Take 35 ml of the above solution and place it in a 50 ml polytetrafluoroethylene-lined hydrothermal reactor, add the pretreated NF, and react at 120℃ for 6 h. After the hydrothermal reactor has completely cooled, remove the nickel foam, rinse it with a large amount of ultrapure water and anhydrous ethanol, and dry it at 60℃ for 12 h to obtain precursor 1.

[0067] Step 3: Place precursor 1 from step 2 into a tube furnace and anneal it in air atmosphere. Increase the temperature to 400℃ at a rate of 5℃ / min and hold for 2 hours. After the reaction is complete and the sample cools naturally, remove the sample to obtain precursor 2.

[0068] Step 4: Take 1*1.5 cm 2 Precursor 2 was immersed in a 0.05 mol / L anhydrous ethanol solution of ferric nitrate at room temperature for 1 hour. After immersion, the nickel foam was removed and air-dried to obtain the final catalyst NiO-Fe.

[0069] Test Example 1 The oxygen evolution test of water electrolysis was performed in an alkaline electrolyte solution using a three-electrode assembly, which included a working electrode, a counter electrode, and a reference electrode. The electrolyte was a 1 mol / L KOH solution.

[0070] NiOx-Fe rich in oxygen vacancies, NiO-Fe with low oxygen vacancies, and untreated nickel foam were prepared according to the methods of Examples 1-3 and Comparative Example 1. Their oxygen evolution performance was tested under laboratory conditions (1 mol / L KOH, room temperature). Figure 4-5 As shown, it exhibits excellent activity and stability in catalyzing the electrochemical oxygen evolution reaction. Example 1, as the most active catalyst, showed a current density of 10 mA / cm² in 1 mol / L KOH solution at room temperature. 2 Only an overpotential of 201 mV is required, and only an overpotential of 283 mV is needed to achieve 1 mA / cm². 2 The current density, and at 0.5 A / cm 2 The catalyst exhibits high reactivity and high stability in alkaline environments, and can effectively improve the oxygen evolution efficiency of water electrolysis, demonstrating excellent alkaline oxygen evolution performance. It can operate stably for more than 1000 hours without activity decay.

[0071] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing an oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst, characterized in that, Includes the following steps: S1. The nickel-based substrate is subjected to acidification pretreatment to obtain the pretreated nickel-based substrate; S2. Dissolve nickel salt, ammonium salt and urea in a solvent to obtain a precursor solution, add the pretreated nickel-based substrate and carry out a hydrothermal reaction, then wash and dry to form a sheet-like nanoarray structure on the surface of the nickel-based substrate to obtain the NiO precursor. S3. Anneal the NiO precursor to obtain NiO. x Catalyst precursor; wherein the annealing treatment includes: introducing an inert gas to purge oxygen from the reaction system, and heating to the annealing temperature under the protection of the inert gas and holding at that temperature for 1-3 hours; at the beginning of the holding stage, switching the inert gas to an argon-hydrogen mixture and maintaining it for 10-30 minutes, and then switching the argon-hydrogen mixture back to the inert gas and continuing until the annealing treatment is completed; wherein the annealing temperature is 200-600℃; S4, the NiO x The catalyst precursor was immersed in an iron source solution and then air-dried to obtain the Fe-doped NiO water electrolysis oxygen evolution catalyst rich in oxygen vacancies.

2. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S1, the acidification pretreatment is as follows: the nickel-based substrate is placed in an acid solution for ultrasonic cleaning for 10-30 minutes, and then the nickel-based substrate is placed in deionized water for ultrasonic cleaning for 10-30 minutes.

3. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 2, characterized in that, The acid solution is at least one of hydrochloric acid solution, nitric acid solution and sulfuric acid solution; The concentration of the acid solution is 10wt%~50wt%; The nickel-based substrate is selected from at least one of nickel foil, nickel foam, and nickel felt.

4. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S2, the nickel salt is selected from at least one of nickel sulfate, nickel nitrate, and nickel chloride; The ammonium salt is selected from at least one of ammonium fluoride, ammonium chloride, and ammonium sulfate; The concentration of the nickel salt in the precursor solution is 0.01~0.1 mol / L; The concentration of the ammonium salt in the precursor solution is 0.1~0.5 mol / L; The concentration of urea in the precursor solution is 0.05~0.5 mol / L.

5. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S2, the temperature of the hydrothermal reaction is 100~150℃, and the time of the hydrothermal reaction is 5~10h; The drying process is carried out at a temperature of 40-80℃ for 10-24 hours.

6. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S3, the annealing time is 1~3h; the heating rate of the annealing is 2~10℃ / min.

7. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S3, the volume ratio of hydrogen in the argon-hydrogen mixture is 5% to 10%. The inert gas is one of argon and nitrogen; The flow rate of the argon-hydrogen mixture is 10~30 ml / min; The flow rate of the inert gas is 50~100 ml / min.

8. The method for preparing the Fe-doped NiO oxygen evolution catalyst rich in oxygen vacancies for water electrolysis according to claim 1, characterized in that, In step S4, the soaking time is 0.5~2 hours; the soaking temperature is room temperature. The iron source solution is an ethanol solution of iron salt; The iron salt in the ethanol solution of the iron salt is selected from at least one of ferric sulfate, ferric nitrate and ferric chloride; The concentration of the ethanol solution of the iron salt is 0.01~0.1 mol / L.

9. An oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of an oxygen-vacancy-rich Fe-doped NiO water electrolysis oxygen evolution catalyst prepared by any one of claims 1-8 in the electrochemical oxygen evolution reaction in an alkaline environment.

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