An OER electrocatalyst and preparation method thereof

Abstract

The present invention relates to the technical field of electrocatalytic materials, and in particular to an OER electrocatalyst and a preparation method thereof, the preparation method comprising: adding an iron salt, a nickel salt, a nitrogen source and a foam nickel substrate to water to obtain a mixed solution; reacting the mixed solution under preset temperature conditions to obtain a precursor; and sulfurizing the precursor to obtain the OER electrocatalyst. In the present invention, the precursor with a nanoflower morphology formed in the hydrothermal process still retains the morphological characteristics of the nanoflowers in the high-temperature sulfurization process, which allows enough active sites to be fully exposed. The heterogeneous interface (Fe3S4 / Ni(OH)2) in the electrocatalyst has a synergistic effect, which improves the charge distribution on the catalyst surface, accelerates the electron transfer rate, and effectively improves the OER catalytic activity. In the stability test under high current density, the Fe3S4 / Ni(OH)2 / NF catalyst also showed excellent long-term stability. At a current density of 100mA cm ‑2 It can work stably for 100 hours.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic materials, and in particular to an OER electrocatalyst and a preparation method thereof. Background Art

[0002] Hydrogen energy (H2, renewable clean energy) has the advantages of abundant sources, high energy density, zero emissions and storability, making it the most viable energy source to replace fossil fuels. Currently, hydrogen production by water electrolysis has become one of the most ideal and feasible methods to provide hydrogen energy. Its reactions include hydrogen evolution reaction (HER, cathode reaction) and oxygen evolution reaction (OER, anode reaction). However, OER (oxygen evolution reaction) is the key half-reaction of electrocatalytic water decomposition, and its multi-electron transfer and slow kinetic process limit the energy utilization efficiency.

[0003] Among various non-precious metal electrocatalysts, nickel-iron-based nanomaterials have attracted widespread attention due to their cost-effectiveness, natural abundance, and favorable electronic configuration. To date, researchers have developed numerous highly efficient electrocatalysts that reduce the overpotential of the OER, such as oxides, selenides, sulfides, phosphides, carbides, nitrides, metal alloys, and (hydroxy)oxides of transition metals (Ni, Fe, Co, etc.). However, the existing non-precious metal electrocatalysts suffer from low cycling stability in alkaline electrolytes, especially at high current densities.

[0004] Therefore, the existing technology needs to be further improved and enhanced. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides an OER electrocatalyst and a preparation method thereof, aiming to solve the problem of low cyclic stability of existing non-precious metal electrocatalysts in alkaline electrolytes.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] In a first aspect, a method for preparing an OER electrocatalyst comprises:

[0008] adding iron salt, nickel salt, nitrogen source and nickel foam substrate into water to obtain a mixed solution;

[0009] reacting the mixed solution under a preset temperature condition to obtain a precursor;

[0010] placing the precursor in a reaction container, and placing sulfur powder on one side of the precursor;

[0011] The reaction vessel is placed in a baking device and heated in an inert atmosphere to obtain the OER electrocatalyst; wherein the heating rate is 2-4°C min-1 ; Heating temperature is 300-400℃;

[0012] The molar ratio of the iron salt to the nickel salt is 1:5.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] As a preferred technical solution, the preparation method of the OER electrocatalyst is described, wherein the iron salt is ferric nitrate nonahydrate or ferric sulfate heptahydrate; the nickel salt is nickel chloride or nickel nitrate hexahydrate; and the nitrogen source is selected from one or more of urea, ammonium fluoride, ammonium sulfate and ammonium nitrate.

[0015] As a preferred technical solution, the preparation method of the OER electrocatalyst is described, wherein the reaction is carried out under preset temperature conditions, wherein the preset temperature is 100-140°C and the reaction time is 2-10h.

[0016] In a second aspect, an OER electrocatalyst is provided, wherein the OER electrocatalyst is prepared using the preparation method described above.

[0017] As a preferred technical solution, the OER electrocatalyst, wherein the OER electrocatalyst has a current density of 50 mA cm in the OER reaction of 1.0 M KOH. -2 When the working potential of the OER electrocatalyst is 191 mV and the current density is 100 mA cm -2 The working potential of the OER electrocatalyst is 208 mV.

[0018] As a preferred technical solution, the OER electrocatalyst, wherein the OER electrocatalyst is at a current density of 100 mA cm -2 The stable working time is not less than 100h.

[0019] Beneficial effects: Compared with the existing technology, the present invention adopts reconstruction engineering and heterogeneous interface engineering to make the prepared OER electrocatalyst have excellent OER catalytic activity in alkaline environment. In the OER reaction, under 1.0M KOH electrolyte, the OER electrocatalyst only needs 191mV and 208mV overpotential to reach 50mA cm -2 and 100mA cm -2 At the same time, the OER electrocatalyst can be -2 It can work stably for more than 100 hours under high current density conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the synthesis of the Fe3S4 / Ni(OH)2 catalyst provided by the present invention;

[0021] Figure 2 are electron micrographs, where a is the SEM image of the Fe / Ni precursor, b is the SEM image of Fe3S4 / Ni(OH)2 / NF, c is the TEM image of Fe3S4 / Ni(OH)2 / NF, d is the HR-TEM image of Fe3S4 / Ni(OH)2 / NF, e is the SEAD image of Fe3S4 / Ni(OH)2 / NF, f is the HAADF-STEM image of Fe3S4 / Ni(OH)2 / NF (with the energy dispersion spectrum embedded in it), and gj are the Ni, Fe, S, and O element mapping images of Fe3S4 / Ni(OH)2 / NF;

[0022] Figure 3 The OER performance test of the catalyst is: where a is the double layer capacitance, b is the Faraday efficiency of the OER process, and c is the current density of 10 mA cm -2 d is a graph showing the chronoamperometric curve of the catalyst, and d is a graph comparing the properties of different catalysts;

[0023] Figure 4 a is the SEM image of Fe3S4 / Ni(OH)2 / NF after OER reaction, and b is the HR-TEM image of Fe3S4 / Ni(OH)2 / NF after OER reaction;

[0024] Figure 5 XPS spectra of Co3S4 / Ni3S2 / NF, Co3S4 / NF and Ni3S2 / NF catalysts: a is the full XPS spectrum, b is Co 2p, c is Ni 2p, and d is S2p;

[0025] Figure 6 UPS spectra of Ni(OH)2 / NF, Fe3S4 / NF and Fe3S4 / Ni(OH)2 / NF catalysts. DETAILED DESCRIPTION

[0026] The present invention provides an OER electrocatalyst and a method for preparing the same. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0027] Those skilled in the art will understand that, unless otherwise stated, the singular forms "a," "an," "said," and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of this application refers to the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, or operations. It should be understood that the term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0028] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0029] It should be understood that the sequence numbers and sizes of the steps in this embodiment do not imply a specific order of execution. The order of execution of each process is determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of this application. All instruments used are commercially available products.

[0030] Combine Figure 1 The preparation method of the OER electrocatalyst provided by the present invention comprises:

[0031] Step 10: Add the iron salt, nickel salt, nitrogen source and nickel foam substrate into water to obtain a mixed solution, wherein the water can be deionized water or distilled water.

[0032] In the present invention, nickel foam (NF) requires pretreatment before use. This can be done by placing the nickel foam in a hydrochloric acid solution and sonicating it. After sonication, the foam is then placed in anhydrous ethanol and sonicated again. The foam is then rinsed with deionized water and dried to obtain a clean NF. Iron salts include, but are not limited to, ferric nitrate nonahydrate and ferric sulfate heptahydrate; nickel salts include, but are not limited to, nickel chloride and nickel nitrate hexahydrate; and nitrogen sources include, but are not limited to, urea, ammonium fluoride, ammonium sulfate, and ammonium nitrate. The molar ratio of the iron salt, nickel salt, and nitrogen source can be 1:5:35. At this ratio, the prepared precursor exhibits a well-defined nanostructured morphology.

[0033] Step 20: reacting the mixed solution under a preset temperature condition to obtain a precursor.

[0034] In the present invention, the mixed solution prepared in step S10 is transferred to a reactor, and the reactor is heated to 100-140° C. and maintained at this temperature for 2-10 hours. After the reaction is completed, a precursor, such as an Fe / Ni precursor, is obtained. The obtained precursor is washed with deionized water and anhydrous ethanol, respectively, and then dried to obtain an Fe / Ni precursor from which impurities have been removed.

[0035] Step 30: performing a sulfurization treatment on the precursor to obtain the OER electrocatalyst.

[0036] In the present invention, the impurity-removed Fe / Ni precursor can be placed on the left side of a porcelain boat, and sulfur powder can be placed on the right side of the boat (or vice versa). The boat is then placed in a tubular furnace and heated under a nitrogen atmosphere. After the temperature reaches a preset temperature, it is kept at this temperature for 2 hours to undergo a high-temperature sulfurization reaction, resulting in a final product labeled Fe3S4 / Ni(OH)2 / NF. High-temperature sulfurization in a tubular furnace can convert the precursor into a sulfide. The introduction of sulfur atoms stabilizes oxygen vacancies, forming a coordination between metal and sulfur, and effectively regulating the electronic structure of the active site.

[0037] Based on the same inventive concept, the present invention also provides an OER electrocatalyst, which is prepared using the above-described preparation method. The specific preparation method has been explained above and will not be repeated here.

[0038] The technical solution provided by the present invention is further explained below through a specific preparation method.

[0039] Example 1

[0040] Fe3S4 / Ni(OH)2 / NF was synthesized using nickel foam as a substrate

[0041] Pretreatment of nickel foam (NF) substrate: A 2 cm × 3 cm × 1.5 mm NF sheet was ultrasonicated in 3 M hydrochloric acid solution for 30 min, ultrasonicated in anhydrous ethanol for 20 min, and ultrasonicated in deionized water for 20 min, then washed three times with deionized water, and finally dried in a vacuum oven at 60 ° C for 3 h to obtain a clean NF.

[0042] Disperse 0.2 mmol of ferric nitrate nonahydrate, 1 mmol of nickel chloride, 2 mmol of ammonium fluoride, and 5 mmol of urea in 20 mL of deionized water and stir at room temperature (24°C) for 1 hour to obtain a solution. The solution, along with the treated NF, was transferred to a 20 mL reactor and reacted in a constant temperature oven at 120°C for 6 hours. The resulting product is labeled Fe / Ni percursor. After the reaction, the product was rinsed three times with deionized water and three times with anhydrous ethanol, then dried at 75°C for 10 hours.

[0043] The precursor obtained above was placed on the left side of the porcelain boat, and 0.1g of sulfur powder was placed on the right side of the porcelain boat. The porcelain boat was placed in a tube furnace. Under a nitrogen atmosphere, the starting temperature was 20℃ and the heating rate was 3℃min. -1 When the temperature reached 350 °C, the temperature was kept at this temperature for 2 h for high-temperature sulfurization reaction to obtain the final product and mark it as Fe3S4 / Ni(OH)2 / NF.

[0044] Comparative Example 1

[0045] Synthesis of Ni(OH)2 / NF

[0046] Pretreatment of nickel foam (NF) substrate: A 2 cm × 3 cm × 1.5 mm NF sheet was ultrasonicated in 3 M hydrochloric acid solution for 30 min, ultrasonicated in anhydrous ethanol for 20 min, and ultrasonicated in deionized water for 20 min, then washed three times with deionized water, and finally dried in a vacuum oven at 60 ° C for 3 h to obtain a clean NF.

[0047] Disperse 1 mmol nickel chloride, 2 mmol ammonium fluoride, and 5 mmol urea in 20 mL of deionized water and stir at room temperature for 1 hour to dissolve to obtain a solution. The solution, along with the treated NF, was transferred to a 20 mL reactor and reacted in a constant temperature oven at 120°C for 6 hours. The resulting product is labeled Ni(OH)2 / NF. After the reaction is complete, the powder sample is washed several times with deionized water and ethanol by centrifugation and then dried at 70°C for 5 hours to obtain Ni(OH)2 / NF.

[0048] Comparative Example 2

[0049] Synthesis of Fe3S4 / NF

[0050] Pretreatment of nickel foam (NF) substrate: A 2 cm × 3 cm × 1.5 mm NF sheet was ultrasonicated in 3 M hydrochloric acid solution for 30 min, ultrasonicated in anhydrous ethanol for 20 min, and ultrasonicated in deionized water for 20 min, then washed three times with deionized water, and finally dried in a vacuum oven at 60 ° C for 3 h to obtain a clean NF.

[0051] Disperse 1 mmol of ferric nitrate nonahydrate, 2 mmol of ammonium fluoride, and 5 mmol of urea in 20 mL of deionized water and stir at room temperature for 1 hour to dissolve. Transfer the solution and the treated NF to a 20 mL reactor and react in a constant temperature oven at 130°C for 6 hours. The resulting product is labeled Fe / NF. After the reaction is complete, rinse the product three times with deionized water and three times with anhydrous ethanol, then dry it at 75°C for 10 hours.

[0052] The precursor obtained above was placed on the left side of the porcelain boat, and 0.1g of sulfur powder was placed on the right side. The porcelain boat was placed in a tube furnace. Under a nitrogen atmosphere, the starting temperature was 20℃ and the heating rate was 3℃min. -1 When the temperature reaches 350 °C, the temperature is kept at this temperature for 2 h for high-temperature sulfurization reaction to obtain the final product and mark it as Fe3S4 / NF.

[0053] The products obtained in Example 1 and Comparative Examples 1 and 2 were tested, and the results were as follows: Figure 2 As shown in the figure, a shows the SEM image of Fe / Ni percursor. The precursor is in the shape of nanoflowers. After high-temperature sulfurization, the Fe3S4 / Ni(OH)2 / NF catalyst still retains the nanoflower morphology intact b, and its nanosheet surface is smooth. c is the TEM image of Fe3S4 / Ni(OH)2 / NF catalyst. According to the high-resolution transmission electron microscopy (HR-TEM) image, the crystal plane spacing of 0.26nm corresponds to the (110) crystal plane of Ni(OH)2, and the crystal plane spacing of 0.25nm corresponds to the (400) crystal plane of Fe3S4 d. The test results show that the catalyst is composed of two phases of Fe3S4 and Ni(OH)2, and a heterogeneous structure material catalyst is successfully prepared. The electron diffraction pattern of the catalyst also further verifies this conclusion. e shows the (200) crystal plane corresponding to Ni(OH)2, and the (551) and (711) crystal planes corresponding to Fe3S4. The EDX energy spectrum shows that the content ratio of Fe and Ni elements is 1:5( Figure 2 In addition, the energy dispersive X-ray spectroscopy shows that Ni and O are evenly distributed in the catalyst, while Fe and S are mainly distributed in the center of the catalyst and less distributed at the edge (e.g. Figure 2 (as shown in gj in ).

[0054] Electrocatalytic performance of Fe3S4 / Ni(OH)2 / NF electrocatalyst

[0055] The OER catalytic activity of the prepared Fe3S4 / Ni(OH)2 / NF catalyst in alkaline conditions (1.0 M KOH solution) was studied using a three-electrode system. -2 At current densities of 1.5, 2.5, and 1.6, the overpotentials required for the Fe3S4 / Ni(OH)2 / NF catalyst were 191, 208, and 280 mV, respectively. This indicates that the coupling between the heterogeneous structures greatly improves the charge transfer rate and significantly optimizes the OER performance of the catalyst. At the same time, the Tafel slope of the Fe3S4 / Ni(OH)2 / NF catalyst is 24.2 mVdec. -1 , lower than Fe3S4 / NF (41.9mV dec -1)、Ni(OH)2 / NF(123.9mV dec -1 ) and RuO2 / NF(140.2mV dec -1 ), indicating that the Fe3S4 / Ni(OH)2 / NF catalyst has the fastest OER kinetics. The Fe3S4 / Ni(OH)2 / NF catalyst has the smallest charge transfer resistance, which demonstrates the excellent interfacial charge transfer kinetics of this catalyst.

[0056] The electrochemical double layer capacitance (C dl ) to evaluate the electrochemically active surface area (ECSA) ( Figure 3 A larger ECSA means more active sites are exposed. -1 ) to conduct CV cycle test, and then the C dl The electrochemical active surface area of the catalyst was evaluated by Figure 3 As can be seen in a, compared with Fe3S4 / NF (7.1mF cm -2 ) and Ni(OH)2 / NF(3.2mF cm -2 ), Fe3S4 / Ni(OH)2 / NF has the largest electrochemical active area (17.4 mF cm -2 ), indicating that more active sites are exposed in Fe3S4 / Ni(OH)2 / NF. Figure 3 In Figure b, the Faradaic efficiency of the Fe3S4 / Ni(OH)2 / NF catalyst was calculated to be 98.64%.

[0057] The stability of the catalyst is characterized by measuring the IT curve of the sample. Figure 3 As shown in c, at 100mA cm -2 Under a constant current density of 1.5, Fe3S4 / Ni(OH)2 / NF can work stably for 100 hours with a loss of only 8%, indicating that the Fe3S4 / Ni(OH)2 / NF catalyst still has excellent long-term stability at high current density, which is significantly improved compared with the stability of other nickel-based sulfides.

[0058] At the same time Figure 3 As shown, the Fe3S4 / Ni(OH)2 / NF catalyst exhibits excellent activity at high current density compared with the existing nickel-iron based catalysts.

[0059] Furthermore, the morphology, surface composition and element valence of Fe3S4 / Ni(OH)2 / NF after OER test were systematically characterized by SEM, HRTEM and XPS. Figure 4 Figure a is the SEM image of Fe3S4 / Ni(OH)2 / NF after OER test. It can be found that the morphology of Fe3S4 / Ni(OH)2 / NF has changed significantly. The originally smooth nano-petals have turned into foam, while the overall shape remains spherical, indicating that the catalyst surface has been reconstructed during the OER process. It can be observed in the HR-TEM image that the lattice fringe spacing of 0.26nm belongs to the (012) crystal plane of Ni(OH)2, while the lattice fringe spacing of 0.22nm belongs to the (402) crystal plane of FeO(OH) Figure 4 (b) Ni(OH)2 still exists, while the Fe3S4 phase undergoes reconstruction during the reaction, transforming in situ into Fe oxyhydroxide and leaching of S, which can further explain the changes in morphology.

[0060] Going further, if Figure 5 As shown, the surface element composition and valence state of the catalyst were further analyzed by X-ray photoelectron spectroscopy (XPS). In the Ni 2p spectrum, the characteristic peaks at 856.5eV and 874.1eV can be attributed to Ni 2+ 2p3 / 2 and 2p1 / 2, compared with the single Ni(OH)2 without heterogeneous structure, the Fe3S4 / Ni(OH)2 / NF catalyst Ni 2+ The characteristic peaks of are all shifted to the positive direction by 0.5eV. Figure 5 In the Fe 2p spectrum, the fitting peaks at 709.5 eV and 719.1 eV can be observed to correspond to Fe 2+ , while the fitting peaks at 711.5eV and 724.5eV correspond to Fe 3+ , and compared with the single Fe3S4 phase, there is a 0.5eV positive shift, Fe 2+ and Fe 3+ The peak area of the Fe3S4 / NF catalyst is larger than that of the Fe3S4 / NF catalyst. The higher binding energy and larger peak area ratio can indicate that the charge transfer phenomenon in the heterogeneous structure changes the surface charge distribution of the single phase, making some Fe 3+ Reduced to Fe 2+ The shift in peak position indicates that there is a strong electronic interaction between the two-phase heterostructure, which greatly promotes the charge transfer.

[0061] The characteristic peaks at 164.3eV and 163.1eV in the S2p spectrum are attributed to 2p1 / 2 and 2p3 / 2. Compared with the single phase, these two peaks move to higher binding energy, with a positive shift of about 0.5eV. At the same time, the peak area of the scan is smaller than that of the single phase due to the heterogeneous structure ( Figure 5 c) in combination Figure 5 The d in Figure 4 confirms that the two characteristic peaks fitted in the O 1s spectrum at 531.3 eV and 532.3 eV are attributable to the M-OH bond and surface-adsorbed water molecules, while the peak at a binding energy of 530.2 eV is attributed to the MO bond. The change in binding energy brought about by the heterostructure demonstrates that the coupling between different phases can optimize the electronic environment of the metal center, regulate the microvalence state of the active site, further improve catalyst performance, promote the reaction process toward a lower energy barrier, and promote efficient OER reactions.

[0062] In addition, the ultraviolet emission spectroscopy (UPS) test ( Figure 6 ) can be calculated to obtain the d-band centers of Fe3S4 / Ni(OH)2 / NF, Ni(OH)2 / NF, and Fe3S4 / NF catalysts. The higher the d-band center position, that is, the closer it is to the Fermi level, the stronger the material's adsorption of intermediates. The d-band center of Fe3S4 / Ni(OH)2 / NF is calculated to be -4.80eV, which is closer to the Fermi level compared to Fe3S4 / NF (-5.04eV) and Ni(OH)2 / NF (-5.49eV). This indicates that the formation of the heterostructure enhances the charge transfer effect and reduces the required adsorption energy, making it easier for the active sites to adsorb and capture reactive free radicals, reducing the reaction energy barrier and efficiently promoting the OER reaction.

[0063] In summary, the present invention provides an OER electrocatalyst and a preparation method thereof. The preparation method comprises: adding an iron salt, a nickel salt, a nitrogen source, and a nickel foam substrate to water to obtain a mixed solution; reacting the mixed solution under predetermined temperature conditions to obtain a precursor; and sulfurizing the precursor to obtain the OER electrocatalyst. In the present invention, the nanoflower-shaped precursor formed during the hydrothermal process retains its nanoflower morphology during the high-temperature sulfurization process, which allows sufficient active sites to be fully exposed. The Fe3S4 / Ni(OH)2 heterojunction exhibits a synergistic effect, improving the charge distribution on the catalyst surface, accelerating the electron transfer rate, and effectively enhancing the OER catalytic activity. (Due to the electronegativity difference between the metal elements, the heterojunction has a strong charge transfer effect. The intact nanoflower morphology increases the surface area of the catalyst, increases the exposure rate of the active sites, and improves the accessibility of the electrolyte during the catalytic process. Simultaneously, the metal oxyhydroxide generated by in situ reconstruction during the OER reaction activates new active sites on the catalyst, significantly enhancing the OER catalytic activity.) The Fe3S4 / Ni(OH)2 / NF catalyst exhibits excellent electrochemical performance, with a current density of 50 mA cm in the OER reaction in 1.0 M KOH. -2 When the working potential of Fe3S4 / Ni(OH)2 / NF is only 191mV, the current density is 100mA cm -2 The working potential of Fe3S4 / Ni(OH)2 / NF is only 208mV. In the stability test at high current density, Fe3S4 / Ni(OH)2 / NF catalyst also showed excellent long-term stability. -2 It can work stably for 100 hours.

[0064] The Fe3S4 / Ni(OH)2 / NF catalyst demonstrates that the simultaneous combination of reconstruction engineering and heterogeneous engineering functionalization strategies can significantly optimize the performance of the catalyst. This work provides a feasible approach for the development of efficient high-current electrocatalysts.

[0065] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing an OER electrocatalyst, characterized in that: include: adding iron salt, nickel salt, nitrogen source and nickel foam substrate into water to obtain a mixed solution; reacting the mixed solution under a preset temperature condition to obtain a precursor; placing the precursor in a reaction container, and placing sulfur powder on one side of the precursor; The reaction vessel is placed in a baking device and heated in an inert atmosphere to obtain an OER electrocatalyst Fe3S4 / Ni(OH)2 / NF; wherein the heating rate is 2-4°C min -1 ; Heating temperature is 300-400℃; The molar ratio of the iron salt to the nickel salt is 1:5; The reaction is carried out under a preset temperature condition, wherein the preset temperature is 100-140° C. and the reaction time is 2-10 hours.

2. The method for preparing an OER electrocatalyst according to claim 1, wherein The iron salt is ferric nitrate nonahydrate or ferric sulfate heptahydrate; the nickel salt is nickel chloride or nickel nitrate hexahydrate; and the nitrogen source is selected from one or more of urea, ammonium fluoride, ammonium sulfate and ammonium nitrate.

3. An OER electrocatalyst, characterized in that The OER electrocatalyst is prepared by the preparation method according to any one of claims 1-2.

4. The OER electrocatalyst according to claim 3, characterized in that The OER electrocatalyst has a current density of 50 mA cm in the OER reaction in 1.0 M KOH. -2 When the overpotential of the OER electrocatalyst is 191 mV and the current density is 100 mA cm -2 The overpotential of the OER electrocatalyst is 208 mV.

5. The OER electrocatalyst according to claim 3, characterized in that The OER electrocatalyst has a current density of 100 mA cm -2 The stable working time is not less than 100h.

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