NiPO-coated Fe-NiS array catalyst as well as preparation method and application thereof

Abstract

The invention discloses a NiPO-coated Fe-NiS array catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst materials. The preparation method comprises the following steps: adding diammonium hydrogen phosphate into ultrapure water, uniformly stirring, putting foamed nickel into the mixture, transferring the mixture into a high-pressure kettle, putting the high-pressure kettle into a drying oven, carrying out hydrothermal treatment to obtain NiP4O11 (recorded as NiPO), cooling to room temperature after the reaction is finished, washing and drying; finally, the NiPO is put into a high-pressure kettle containing ferric nitrate nonahydrate and thiosulfate pentahydrate to be subjected to second-step hydrothermal treatment, and NiPO-coated Fe-NiS is obtained; according to the preparation method disclosed by the invention, the NiPO-coated Fe-NiS microrod-nanosheet array catalyst combined with iron doping and double anion layers is prepared, and the NiPO-coated Fe-NiS anode catalyst can respectively realize the current density of 100 mA / cm < 2 >, 500 mA / cm < 2 > and 1000 mA / cm < 2 > only by the overpotentials of 199 mV, 245 mV and 265 mV in a seawater electrolysis system of 6 M KOH; under the condition of high current density of 500 mA / cm < 2 >, the catalyst can stably operate for 1500 hours, and shows the comprehensive performance advantages of high catalytic activity and long-term durability in industrial alkaline seawater.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a NiPO@Fe-NiS array catalyst, its preparation method, and its applications. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is considered one of the important pathways to achieve energy structure transformation and carbon neutrality goals. Currently, among various hydrogen production technologies, water electrolysis driven by renewable energy has attracted widespread attention due to its clean process and high sustainability. However, traditional water electrolysis processes heavily rely on high-purity deionized water, which will further exacerbate freshwater shortages under large-scale application conditions, limiting its widespread application. Seawater accounts for approximately 96% of the Earth's total water resources, with abundant reserves and wide distribution, and is considered a virtually inexhaustible source of hydrogen. Combining seawater electrolysis with offshore wind or photovoltaic power generation systems in coastal areas can not only reduce costs in seawater desalination, transportation, and storage, but also effectively reduce freshwater consumption and carbon emissions. Therefore, direct seawater electrolysis is considered a sustainable hydrogen production pathway with significant application prospects. However, seawater electrolysis still faces many technical challenges in actual operation, particularly in the anodic oxygen evolution reaction process. Natural seawater contains a high concentration of chloride ions (Cl-). - During the anodic reaction, it easily triggers competing reactions such as the chlorine evolution reaction (CER), accelerating the corrosion and failure of the electrode material. Although it is thermodynamically more advantageous under alkaline conditions, its reaction kinetics are more favorable because it only involves two electron transfers. This makes it prone to occupying a portion of the current in actual reactions, leading to decreased energy efficiency and the formation of corrosive and toxic chlorine-containing species. Meanwhile, Cl... - Corrosion can also lead to metal dissolution and loss of active sites, causing rapid degradation of the anode catalyst's performance and making it difficult to achieve long-term stable operation.

[0003] Targeting the positive extreme Cl - The corrosion and side reactions caused by this reaction have been extensively studied in existing technologies, mainly focusing on catalyst composition regulation and interface structure design. On the one hand, by introducing heterogeneous elements to chemically regulate the catalyst, the electronic structure of the active center can be altered, optimizing the adsorption energy of oxygen evolution reaction (OER) intermediates, thereby improving the intrinsic activity of OER and, to some extent, inhibiting Cl-. - On the other hand, by constructing an anion-rich protective layer on the catalyst surface, a negatively charged barrier structure can be formed at the interface, utilizing electrostatic repulsion and steric hindrance effects to prevent Cl adsorption. - Migrate to the active site while maintaining OH - Effective transmission of Cl, thereby slowing down Cl -Corrosion and inhibition of the chlorine evolution reaction. Furthermore, studies have shown that surface-adsorbed anions may also participate in regulating the OER reaction pathway under specific conditions, positively impacting catalytic activity. While the above strategies have improved the performance of seawater electrolysis anodes to some extent, most existing technologies focus on a single regulatory mechanism, either enhancing catalytic activity through chemical regulation or strengthening resistance to Cl through physical protection. - Corrosion resistance, difficult to achieve at high Cl levels - The goal is to achieve both high activity and high stability under high concentration and high current density conditions. Highly active catalysts often lack durability in highly corrosive environments, while catalysts with strong corrosion resistance may suffer from limited active sites and slower reaction kinetics due to interfacial shielding effects. This inherent contradiction between activity and stability is particularly pronounced under long-term operation and industrial conditions. Furthermore, existing single anion exchange protective layers are inadequate for Cl... - The repulsive ability is limited, making it difficult to support the electrode in high Cl- environments. - To achieve long-term stable operation in a concentration system, it is urgently needed to develop a method that can synergistically achieve high OER activity and strong Cl-resistance in a unified system. - This invention proposes a method for designing anode catalysts to overcome key technological bottlenecks in the practical application of seawater electrolysis. The method involves a simple two-step hydrothermal synthesis of NiPO@Fe-NiS microrod-nanosheet array catalysts. This method enhances activity by constructing highly active Ni sites and by building PO4 groups. 3- SO4 2- Strong repulsion of Cl by the double anion layer - Without hindering OH - The adsorption allows it to operate stably for extended periods under high activity in industrial alkaline seawater. Summary of the Invention

[0004] Based on this, in order to solve one of the above-mentioned technical problems, the present invention provides a NiPO@Fe-NiS array catalyst, its preparation method, and its application. The specific technical solution is as follows:

[0005] A NiPO@Fe-NiS array catalyst comprises a NiPO microrod substrate and Fe-NiS nanosheets grown in situ on its surface, forming a hierarchical micro-nano structure array. The NiPO@Fe-NiS array catalyst has uniformly distributed Ni, Fe, P, O, and S elements, and its surface also contains PO4. 3- SO4 2- Double anion layer.

[0006] In addition, the present invention also provides a method for preparing a NiPO@Fe-NiS array catalyst, the preparation method comprising the following steps: S1. Dissolve hydrogen phosphate in water and stir until homogeneous to obtain a phosphate solution; S2. The cleaned bulk nickel is immersed in the phosphate solution, placed in an autoclave, hydrothermally treated, cooled, washed, and dried to obtain the NiPO precursor; S3. Dissolve iron salts and thiosulfates in water and stir until homogeneous to obtain a mixed solution containing iron and sulfur; S4. Immerse the NiPO precursor in the mixed solution containing iron and sulfur, place it in an autoclave, and hydrothermally treat it at 120℃~130℃ for 8h~10h. After cooling, wash and dry to obtain NiPO@Fe-NiS microrod-nanosheet array catalyst.

[0007] Further, in step S1, the hydrogen phosphate is at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, or ammonium dihydrogen phosphate.

[0008] Further, in step S2, the bulk nickel is at least one of nickel foam, nickel sheet, nickel mesh, or nickel felt.

[0009] Furthermore, in step S2, the mixture is subjected to hydrothermal treatment at 150℃~180℃ for 10h~12h.

[0010] Further, in step S3, the iron salt is at least one of ferric chloride and ferric nitrate; the thiosulfate is at least one of sodium thiosulfate and potassium thiosulfate.

[0011] Further, in step S1, the concentration of the phosphate solution is 1.5 mmol / L to 2 mmol / L.

[0012] Further, in step S3, the concentration of iron ions in the iron salt solution is 0.5 mmol / L to 0.9 mmol / L, and the concentration of sulfur in the thiosulfate solution is 0.5 mmol / L to 1 mmol / L.

[0013] Furthermore, in step S4, the drying temperature is 60℃~65℃, and the drying time is 2h~3h.

[0014] In addition, the present invention also provides an application of the NiPO@Fe-NiS array catalyst, wherein the NiPO@Fe-NiS array catalyst is used in the preparation of an anode electrode.

[0015] Compared with existing technologies, its beneficial effects include: 1. This invention successfully constructed a hierarchical array structure of microrods and nanosheets using a two-step hydrothermal method. The structure uses NiPO microrods as a framework, with Fe-NiS nanosheets grown in situ vertically on the surface, forming an open and porous micro-nano framework. This design significantly increases the specific surface area of ​​the electrode and the density of exposed active sites, while also facilitating rapid bubble escape and ion transport during the reaction, thereby greatly improving catalytic reaction kinetics and active site utilization.

[0016] 2. PO4 formed in situ on the surface of the catalyst of the present invention 3- SO4 2- The double anion layer structure effectively blocks high concentrations of Cl in seawater through electrostatic repulsion. - The migration and adsorption to active sites fundamentally inhibit chlorine evolution side reactions and chloride ion corrosion. Simultaneously, this layer resists OH... - The transport resistance is small, ensuring the efficient execution of the OER reaction in an alkaline environment, thus successfully solving the core technical problem of balancing catalytic activity and long-term stability in seawater electrolysis.

[0017] 3. This invention effectively modulates the electronic structure of the active center (Ni site) by introducing Fe element for doping, thus optimizing the OER reaction intermediates (such as...). The adsorption energy of OOH significantly enhances the electrocatalytic activity of the catalyst.

[0018] 4. The catalyst prepared by this invention not only has high activity and durable stability, but also has a simple overall preparation process, which is only a simple two-step hydrothermal synthesis with a short reaction time. The raw materials selected, such as nickel substrate, iron salt, phosphate and thiosulfate, are all inexpensive and readily available non-precious metal materials. The process conditions are mild and have good repeatability, and it has the potential for large-scale industrial production and application. Attached Figure Description

[0019] The invention will be further understood from the following description taken in conjunction with the accompanying drawings. The components in the drawings are not necessarily drawn to scale, but rather the emphasis is on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0020] Figure 1 (a) and (b) are scanning electron microscope (SEM) images of NiPO in Example 1; (c) and (d) are SEM images of NiPO@Fe-NiS in Example 1; Figure 2 (a) and (b) are transmission electron microscope (TEM) images and elemental distribution maps of NiPO@Fe-NiS in Example 1, respectively; Figure 3The spectral lines of NiPO and NiPO@Fe-NiS in Example 1 are shown below: (a) XRD pattern, (b) Raman pattern; Figure 4 The following are the OER performance graphs of NiPO and NiPO@Fe-NiS electrodes in seawater in 6MKOH in Example 1: (a) Linear sweep voltammetry (LSV) curves; (b) Overpotentials at current densities of 100, 500 and 1000 mA / cm2; (c) Vt graph of constant current electrolysis durability test at a constant current density of 500 mA / cm2 in seawater solution of 6MKOH. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] The implementation schemes of the present invention will now be described in detail with reference to specific embodiments.

[0024] Example 1: Sample preparation: Commercial nickel foam (2cm×5cm) was sequentially sonicated with 3M HCl for 15min, sonicated with anhydrous ethanol for 5min, rinsed with deionized water for 1min, and then dried at 60℃ for later use. Dissolve 1.5 mmol (NH4)2HPO4 in 60 mL of deionized water, stir for 10 min, and then let stand in an ice-water bath for 2 min to obtain (NH4)2HPO4 solution. The pretreated nickel foam was immersed in the (NH4)2HPO4 solution and hydrothermally treated at 180°C for 12 hours. After natural cooling, it was gently rinsed with deionized water and air-dried at room temperature to obtain the NiPO precursor. The NiPO precursor was immersed in 60 mL of a homogeneous solution containing 0.5 mmol Fe(NO3)3·9H2O and 0.5 mmol Na2S2O3·5H2O, and hydrothermally treated at 120 °C for 8 h. After cooling, rinsing (2 min), and drying, the NiPO@Fe-NiS microrod-nanosheet array catalyst was obtained.

[0025] Electrochemical performance testing employed a three-electrode system: NiPO@Fe-NiS as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and 6MKOH seawater solution as the electrolyte.

[0026] Table 1 lists the electrode's performance at 100, 500, and 1000 mA / cm during oxygen production. 2 The overpotentials at current densities were 199, 245, and 265 mV, respectively, with the sample in Example 1 showing the best performance.

[0027] Example 2: Sample preparation: Commercial nickel foam (2cm×5cm) was sonicated in 3M HCl for 15min, sonicated in anhydrous ethanol for 5min, rinsed with deionized water for 1min, and dried at 60℃ for later use. Dissolve 1.25 mmol (NH4)2HPO4 in 60 mL of deionized water, stir magnetically for 10 min, and then let stand in an ice-water bath for 2 min to obtain (NH4)2HPO4 solution. The pretreated nickel foam was immersed in the (NH4)2HPO4 solution, hydrothermally treated at 180°C for 10 hours, naturally cooled to room temperature, gently rinsed with deionized water, and air-dried at room temperature to obtain the NiPO precursor. The NiPO precursor was immersed in 60 mL of a homogeneous solution containing 0.4 mmol Fe(NO3)3·9H2O and 0.5 mmol Na2S2O3·5H2O, and hydrothermally treated at 120 °C for 8 h. After cooling, rinsing (2 min), and drying, the NiPO@Fe-NiS microrod-nanosheet array catalyst was obtained.

[0028] Electrochemical testing employed a standard three-electrode system: NiPO@Fe-NiS as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and 6MKOH seawater as the electrolyte.

[0029] Table 1 summarizes the results of this electrode at 100, 500, and 1000 mA / cm. 2 The overpotentials at current densities are 210, 249, and 270 mV, respectively.

[0030] Example 3: Sample preparation: Commercial nickel foam (2cm×5cm) was sonicated in 3M HCl for 15min, sonicated in anhydrous ethanol for 5min, rinsed with deionized water for 1min, and dried at 60℃ for later use. Dissolve 1 mmol (NH4)2HPO4 in 60 mL of deionized water, stir magnetically for 10 min, and then place in an ice-water bath and let stand for 2 min to obtain (NH4)2HPO4 solution. The pretreated nickel foam was immersed in the (NH4)2HPO4 solution and hydrothermally treated at 180°C for 10 hours. After naturally cooling to room temperature, it was gently rinsed with deionized water and air-dried at room temperature to obtain the NiPO precursor. The NiPO precursor was immersed in 60 mL of a homogeneous solution containing 0.4 mmol Fe(NO3)3·9H2O and 0.4 mmol Na2S2O3·5H2O, and hydrothermally treated at 120 °C for 8 h. After cooling, rinsing (2 min), and drying, the NiPO@Fe-NiS microrod-nanosheet array catalyst was obtained.

[0031] Electrochemical testing employed a standard three-electrode system: NiPO@Fe-NiS as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and 6MKOH seawater as the electrolyte.

[0032] Table 1 summarizes the results of this electrode at 100, 500, and 1000 mA / cm. 2 The overpotentials at current densities are 225, 254, and 277 mV, respectively.

[0033] Example 4: Sample preparation: Commercial nickel foam (2cm×5cm) was sonicated in 3M HCl for 15min, sonicated in anhydrous ethanol for 5min, rinsed with deionized water for 1min, and dried at 60℃ for later use. Dissolve 1 mmol (NH4)2HPO4 in 60 mL of deionized water, stir magnetically for 10 min, and then place in an ice-water bath and let stand for 2 min to obtain (NH4)2HPO4 solution. The pretreated nickel foam was immersed in the (NH4)2HPO4 solution and hydrothermally treated at 180°C for 10 hours. After naturally cooling to room temperature, it was gently rinsed with deionized water and air-dried at room temperature to obtain the NiPO precursor. The NiPO precursor was immersed in 60 mL of a homogeneous solution containing 0.4 mmol Fe(NO3)3·9H2O and 0.3 mmol Na2S2O3·5H2O, and hydrothermally treated at 120 °C for 8 h. After cooling, rinsing (2 min), and drying, NiPO@Fe-NiS microrod-nanosheet array catalyst was obtained.

[0034] Electrochemical testing employed a standard three-electrode system: NiPO@Fe-NiS as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and 6MKOH seawater as the electrolyte.

[0035] Table 1 summarizes the results of this electrode at 100, 500, and 1000 mA / cm. 2 The overpotentials at current densities are 233, 267, and 286 mV, respectively.

[0036] Example 5: Sample preparation: Commercial nickel foam (2cm×5cm) was sonicated in 3M HCl for 15min, sonicated in anhydrous ethanol for 5min, rinsed with deionized water for 1min, and dried at 60°C for later use. Dissolve 0.5 mmol (NH4)2HPO4 in 60 mL of deionized water, stir magnetically for 10 min, and then let stand in an ice-water bath for 2 min to obtain (NH4)2HPO4 solution. The pretreated nickel foam was immersed in the (NH4)2HPO4 solution and hydrothermally treated at 180°C for 10 hours. After naturally cooling to room temperature, it was gently rinsed with deionized water and air-dried at room temperature to obtain the NiPO precursor. The NiPO precursor was immersed in 60 mL of a homogeneous solution containing 0.2 mmol Fe(NO3)3·9H2O and 0.4 mmol Na2S2O3·5H2O, and hydrothermally treated at 120 °C for 8 h. After cooling, rinsing (2 min), and drying, NiPO@Fe-NiS microrod-nanosheet array catalyst was obtained.

[0037] Electrochemical testing employed a standard three-electrode system: NiPO@Fe-NiS as the working electrode, Hg / HgO as the reference electrode, a graphite rod as the counter electrode, and 6MKOH seawater as the electrolyte.

[0038] Table 1 summarizes the results of this electrode at 100, 500, and 1000 mA / cm. 2 The overpotentials at current densities are 257, 284, and 300 mV, respectively.

[0039] Table 1: Performance test results of Examples 1-5

[0040] Analysis of the data in Table 1 shows that Example 1 exhibits the best performance, especially at industrial-grade high current densities (500 and 1000 mA / cm²), demonstrating a significant advantage. This indicates that by systematically adjusting the preparation parameters, a series of catalysts with predictable performance can be obtained, proving the reliability and process controllability of the preparation method. This effectively verifies that the present invention, through the construction of Fe-doped active sites and PO₃, achieves this result. 3- SO4 2- The synergistic effect of the double anion protective layer effectively solves the core problem of the contradiction between activity and stability in seawater electrolysis, resulting in excellent overall performance and stability.

[0041] In addition, combined Figures 1-4 Further analysis is needed. Figure 1(a) and (b) are scanning electron microscope (SEM) images of NiPO in Example 1; (c) and (d) are SEM images of NiPO@Fe-NiS in Example 1. The SEM images show that the precursor NiPO consists of a large number of microrods tightly arranged in an array. After the second hydrothermal treatment, NiPO@Fe-NiS completely retains its original framework. Figure 1 (c)-(d)) confirmed that the introduction of Fe and S did not destroy the morphology of nickel phosphide; at the same time, dense nanosheets were grown in situ on the surface of the microrods, constructing a hierarchical micro-nano structure, which significantly increased the surface exposed area.

[0042] Figure 2 (a) and (b) are transmission electron microscopy (TEM) images and elemental distribution maps of NiPO@Fe-NiS in Example 1, respectively. TEM shows that the nanosheets overlap and are vertically anchored to the surface of the micrometer rods, forming an open and porous micro-nano framework, which is consistent with the SEM images. The elemental distribution map shows that the five elements Ni, Fe, O, S, and P are evenly distributed without local agglomeration. Ni, P, and O are mainly distributed on the micrometer rods, while Fe and S are distributed on the nanosheets. This core-shell structure is beneficial for improving the utilization rate of active sites.

[0043] Figure 3 The spectra of NiPO and NiPO@Fe-NiS in Example 1 are shown below: (a) XRD pattern, (b) Raman pattern. (c) and (d) are the time-of-flight secondary ion mass spectra of NiPO@Fe-NiS in Example 1 after the OER reaction, respectively, showing SO42-. 2- and PO4 3- The signal is evident from the XRD pattern, where NiP4O is simultaneously present in NiPO@Fe-NiS. 11 The presence of characteristic peaks in Ni3S2 confirms the coexistence of the two phases. Raman spectroscopy further verifies that NiPO exhibits characteristic peaks at 1003 and 1066 cm⁻¹. -1 The location is PO4 3- Vibration, NiPO@Fe-NiS after introducing Fe and S at 350 cm⁻¹ -1 New Ni-S peaks appear at 996 and 1000 cm⁻¹. -1 The location is PO4 3- Vibrations, along with the above, collectively demonstrate the successful synthesis of the rod-shaped nanosheet array NiPO@Fe-NiS. Importantly, SO42- was detected in the time-of-flight secondary ion mass spectrometry. 2- and PO4 3- The signal confirmed the existence of the double anion layer, which possesses the ability to repel Cl. - It has the effect, but it does not hinder OH. - Adsorption.

[0044] Figure 4 The OER performance of NiPO and NiPO@Fe-NiS electrodes in seawater at 6 MKOH in Example 1 is shown in the graphs: (a) Linear sweep voltammetry (LSV) curves; (b) 100, 500, and 1000 mA / cm². 2 Overpotential at current density; (c) constant 500 mA / cm² in a seawater solution of 6 MKOH. 2 The Vt graph shows the durability test results of constant current electrolysis at current density. The graph demonstrates that the regulated NiPO@Fe-NiS electrode exhibits excellent OER activity and stability in the electrolysis of alkaline seawater.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. 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 protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A NiPO@Fe-NiS array catalyst, characterized in that, The NiPO@Fe-NiS array catalyst comprises a NiPO microrod substrate and Fe-NiS nanosheets grown in situ on its surface, forming a hierarchical micro-nano structure array. The NiPO@Fe-NiS array catalyst has uniformly distributed Ni, Fe, P, O, and S elements, and its surface also contains PO4. 3- SO4 2- Double anion layer.

2. A method for preparing a NiPO@Fe-NiS array catalyst, characterized in that, The preparation method is used to prepare the NiPO@Fe-NiS array catalyst as described in claim 1, and the preparation method includes the following steps: S1. Dissolve hydrogen phosphate in water and stir until homogeneous to obtain a phosphate solution; S2. The cleaned bulk nickel is immersed in the phosphate solution, placed in an autoclave, hydrothermally treated, cooled, washed, and dried to obtain the NiPO precursor; S3. Dissolve iron salts and thiosulfates in water and stir until homogeneous to obtain a mixed solution containing iron and sulfur; S4. Immerse the NiPO precursor in the mixed solution containing iron and sulfur, place it in an autoclave, and hydrothermally treat it at 120℃~130℃ for 8h~10h. After cooling, wash and dry to obtain NiPO@Fe-NiS microrod-nanosheet array catalyst.

3. The preparation method according to claim 2, characterized in that, In step S1, the hydrogen phosphate is at least one of sodium dihydrogen phosphate, potassium dihydrogen phosphate, or ammonium dihydrogen phosphate.

4. The preparation method according to claim 2, characterized in that, In step S2, the bulk nickel is at least one of nickel foam, nickel sheet, nickel mesh, or nickel felt.

5. The preparation method according to claim 2, characterized in that, In step S2, the sample is subjected to hydrothermal treatment at 150℃~180℃ for 10h~12h.

6. The preparation method according to claim 2, characterized in that, In step S3, the iron salt is at least one of ferric chloride and ferric nitrate; the thiosulfate is at least one of sodium thiosulfate and potassium thiosulfate.

7. The preparation method according to claim 2, characterized in that, In step S1, the concentration of the phosphate solution is 1.5 mmol / L to 2 mmol / L.

8. The preparation method according to claim 2, characterized in that, In step S3, the concentration of iron ions in the iron salt solution is 0.5 mmol / L to 0.9 mmol / L, and the concentration of sulfur in the thiosulfate solution is 0.5 mmol / L to 1 mmol / L.

9. The preparation method according to claim 2, characterized in that, In step S4, the drying temperature is 60℃~65℃ and the drying time is 2h~3h.

10. An application of a NiPO@Fe-NiS array catalyst, characterized in that, The application is the use of the NiPO@Fe-NiS array catalyst of claim 1 in the preparation of an anode electrode.

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