An automated method for selective construction of multistage heterostructure electrocatalysts

Abstract

The application discloses a method for selectively constructing a multistage heterostructure electric catalyst, and relates to an iron-containing layered double hydroxide, which comprises a NiFe nanosheet, a conductive substrate, and a FeW alloy layer loaded on the conductive substrate, wherein the NiFe nanosheet is wrapped on the surface of the conductive substrate and is connected in a staggered mode. The multistage heterostructure electric catalyst has good conductivity, and the multistage heterostructure layer and the high-activity surface of the electric catalyst have a synergistic promotion effect, which improves the electric catalytic performance and greatly improves the material stability. The preparation method of the multistage heterostructure electric catalyst ingeniously constructs the high-activity NiFe LDH on the surface of the FeW alloy layer, which improves the catalytic activity and avoids the use of a binder.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology, and in particular to an automated method for selectively constructing multi-level heterogeneous electrocatalysts. Background Technology

[0002] Hydrogen energy, as a promising secondary energy source, has attracted the interest of many researchers. It is produced by generating electricity from solar and wind power through water electrocatalysis. In water electrocatalysis, the electrocatalyst is one of the most important core components of the overall water splitting device, used to reduce overpotential caused by polarization, thereby improving energy transfer efficiency.

[0003] Compared to HER (hydrogen evolution reaction at the cathode), OER (oxygen evolution reaction at the anolyte) is a more energy-intensive process in water splitting because this half-reaction involves more complex proton / electron coupling steps. Effective OER electrocatalysis is crucial for the overall efficiency of water splitting, thus creating an urgent need for oxygen evolution electrodes (or electrocatalysts) with sufficient catalytic activity and stability. To date, IrO2 and RuO2 are the benchmark OER catalysts due to their high catalytic activity. However, these precious metals are expensive, have low reserves, and are unsustainably supplied, making them unsuitable for large-scale applications. Therefore, much research has focused on developing low-cost OER electrocatalysts based on first-row transition metals and their oxides, such as iron phosphate composites, nickel borate composites, nickel oxide nanoparticles, and cobalt oxide films. These catalysts exhibit good OER activity while significantly reducing manufacturing costs. Among these catalysts, nickel-based and iron-based composites have shown promise as active OER catalysts, typically requiring an overpotential of around 300–450 mV to provide 10 mA cm⁻¹. -2 The current density. NiFe layered bimetallic hydroxides (NiFe LDHs) are considered one of the most promising water splitting electrocatalysts in alkaline electrolyte solutions due to their low cost, unique layered structure, and tunable electronic structure, as they exhibit high activity and stability.

[0004] Most of the multi-level heterostructure electrocatalysts in related patents, especially transition metal-based OER composite catalysts, are powders that are coated onto conductive substrates with the help of polymer binders (such as Nafion). Using electrically insulating binders reduces the contact area between the electrolyte and the catalytic active sites, deteriorating electrode conductivity and leading to decreased electrocatalytic performance. Electrode stability is also poor, especially under high current density and strong gas evolution conditions, where adhesive OER catalysts are prone to peeling off from the substrate. Considering these concerns, finding new low-cost methods for constructing multi-level heterostructure electrocatalysts is crucial for the future development of transition metal-derived catalysts.

[0005] Currently, widely used methods for preparing multi-level heterogeneous electrocatalysts include hydrothermal / solvothermal methods, chemical vapor deposition, and microwave-assisted heating methods. However, the composite materials prepared by these methods typically exhibit poor reproducibility, poor homogeneity, and high agglomeration. For example, high-temperature calcination, hydrothermal, or solvothermal methods involve complex steps, harsh reaction conditions, generate toxic waste, and consume large amounts of energy. In particular, it is difficult to reproduce similar electrocatalysts in some complex reaction systems with low controllability.

[0006] Metals, due to their low electrode potential, readily form galvanic cells with atmospheric water and oxygen when exposed to air. This leads to the dissolution of metal ions and the formation of rust on the material surface, often causing significant damage to industrial production. Therefore, numerous measures have been implemented to prevent this reaction, such as coloring coatings, electrochemical protection, and the addition of corrosion inhibitors. However, patented technologies utilizing the spontaneous nature of galvanic cells to prepare electrocatalysts are rare. In fact, oxides produced by redox reactions occurring in the microscopic regions of metal surfaces can be used as catalytic materials for electrochemical reactions through appropriate treatment. The key to this technology lies in how to prepare effective active species while avoiding rust formation. Summary of the Invention

[0007] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a method for selectively constructing a hierarchical heterostructure electrocatalyst. This hierarchical heterostructure electrocatalyst exhibits good conductivity, and the hierarchical heterostructure layers and highly active surface of the electrocatalyst have a synergistic promoting effect, improving its electrocatalytic performance while also significantly enhancing material stability. The preparation method of this hierarchical heterostructure electrocatalyst cleverly constructs a highly active NiFe LDH on the surface of a FeW alloy layer, improving its catalytic activity while avoiding the use of binders.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a multi-level heterostructure electrocatalyst comprising an iron-containing layered double hydroxide, wherein the iron-containing layered double hydroxide comprises NiFe nanosheets and a conductive substrate; the conductive substrate is supported with an FeW alloy layer; the NiFe nanosheets are wrapped around the surface of the conductive substrate; and the NiFe nanosheets are interleaved.

[0010] In some embodiments of the present invention, the thickness of the NiFe nanosheet is 5-10 nm; the size of the NiFe nanosheet is approximately 500 nm.

[0011] In some embodiments of the present invention, the loading of the FeW alloy layer on the conductive substrate is 10-15 mg / cm³. 2 .

[0012] In some embodiments of the present invention, the conductive substrate includes at least one of nickel foam, copper foam, titanium felt, and carbon cloth.

[0013] In some embodiments of the present invention, the conductive substrate may be a pretreated conductive substrate.

[0014] In some embodiments of the present invention, the pretreatment step of the pretreated conductive substrate specifically includes: cutting the nickel foam, ultrasonically cleaning it with hydrochloric acid, deionized water, and ethanol respectively, and placing it in an ethanol solution for later use.

[0015] In some embodiments of the present invention, the metal W in the FeW alloy layer is formed by doping.

[0016] In a second aspect, the present invention provides a method for preparing the aforementioned multi-level heterostructure electrocatalyst, comprising the following steps:

[0017] A conductive substrate loaded with FeW alloy layers is immersed in a mixed solution of nickel and chloride salts for reaction, followed by post-treatment to obtain a multi-level heterostructure electrocatalyst.

[0018] This invention introduces divalent cations, such as Ni, into the galvanic cell environment. 2+ Iron-containing layered hydrogen hydroxides (LDHs) can spontaneously form on the surface of iron-based materials instead of forming inactive rust. Furthermore, the LDHs generated by this method exist as well-oriented, grain-bound nanosheet arrays, interwoven to form a hierarchical heterostructure electrocatalyst. This microstructure is favorable for electrochemical reactions. These galvanic cell reactions typically occur under weakly acidic or neutral conditions and involve oxygen.

[0019] The above reaction process often generates hydroxides on the metal surface, which can serve as active substances for electrocatalysis. By comparing metals (EM) and oxygen (E)...O2 The standard electrode potential value of EM can be used to estimate the probability of a galvanic cell reaction occurring. When EM is lower than E... O2 At this time, the reaction can occur spontaneously. E O2 The value can be calculated using the following formula.

[0020] E O2 =1.22 - 0.0591 * pH Formula 1

[0021] Fe→Fe 2+ +2e - Formula 2

[0022] Fe 2+ →Fe 3+ +e - Formula 3

[0023] O2 + 2H2O + 4e - →4OH - Formula 4

[0024] Fe 3+ +Ni 2+ +OH - +CO3 2- →LDH Formula 5

[0025] E is affected by the pH value of the surrounding environment. For example, E O2 The value at (pH=4) is 0.9836V, which is greater than the E of Fe. Fe 2+ / Fe(-0.447V) leads to the dissolution of Fe.

[0026] Generally, redox processes occur when the electrode potential of a metal is lower than that of oxide ions in the surrounding environment. In fact, the greater the electrode potential difference, the easier it is for the metal to dissolve.

[0027] This invention discloses an automated method for selectively constructing multi-level heterogeneous structures and applies it to an efficient water oxidation process. Because the iron electrode has a relatively negative potential, the galvanic cell reaction process readily occurs; this can be achieved by immersing an iron-based alloy material in an aqueous solution containing a certain amount of divalent cations at room temperature. The electrode is manufactured through a spontaneous redox process, requiring no additional energy consumption.

[0028] In some embodiments of the present invention, the reaction temperature is 25°C-80°C; the reaction time is 1h-12h.

[0029] In some embodiments of the present invention, the nickel salt includes at least one of nickel sulfate, nickel nitrate, and nickel chloride.

[0030] In some embodiments of the present invention, the concentration of the nickel salt is 5 g / L-25 g / L.

[0031] In some embodiments of the present invention, the chloride salt includes at least one of sodium chloride, potassium chloride, and ammonium chloride.

[0032] In some embodiments of the present invention, the concentration of the chloride salt is 10 g / L to 40 g / L.

[0033] In some embodiments of the present invention, the solvent for the nickel salt and chloride salt mixed solution is water.

[0034] In some embodiments of the present invention, the post-treatment involves washing with deionized water and ethanol, followed by drying.

[0035] In some embodiments of the present invention, the preparation of the FeW alloy layer loaded on the conductive substrate includes the following steps:

[0036] Using a conductive substrate as the cathode and a graphite rod as the anode, the cathode and anode are immersed in an electrodeposition solution for deposition and purification to obtain a conductive substrate loaded with an FeW alloy layer.

[0037] The electrodeposition solution comprises iron salts and tungstates.

[0038] In some embodiments of the present invention, the pH of the electrodeposition solution is 4 to 5.

[0039] In some embodiments of the present invention, the pH of the electrodeposition solution is adjusted using olefinic acid, and the concentration is 0.5–6 mol / L.

[0040] In some embodiments of the present invention, the dilute acid includes at least one of nitric acid, hydrochloric acid, and sulfuric acid.

[0041] In some embodiments of the present invention, the iron salt includes at least one of ferrous chloride, ferrous oxalate, and ferrous carbonate.

[0042] In some embodiments of the present invention, the concentration of the iron salt is 50-100 g / L.

[0043] In some embodiments of the present invention, the tungstate includes Na2WO4·2H2O and (NH4)6W7O. 24 At least one of ·6H2O.

[0044] In some embodiments of the present invention, the concentration of the tungstate is 10-18 g / L.

[0045] In some embodiments of the present invention, the deposition temperature is 0–25°C, the deposition voltage is 2–10V, and the deposition time is 2–10 min.

[0046] In some embodiments of the present invention, the purification process involves washing with deionized water and ethanol, followed by drying.

[0047] In some embodiments of the present invention, the electrodeposition solution further includes a ligand and a conductive salt.

[0048] In some embodiments of the present invention, the ligand includes at least one of sodium citrate, ethylenediaminetetraacetic acid, tartaric acid, and triethanolamine.

[0049] In some embodiments of the present invention, the conductive salt includes at least one of sulfate, chloride, and sulfate.

[0050] In some embodiments of the present invention, the conductive salt includes at least one of sodium sulfate, potassium chloride, potassium sulfate, and sodium chloride.

[0051] In some embodiments of the present invention, the concentration of the ligand is 40-60 g / L.

[0052] In some embodiments of the present invention, the concentration of the conductive salt is 1-5 g / L.

[0053] A third aspect of the present invention proposes the application of the aforementioned multi-level heterostructure electrocatalyst in electrocatalytic oxygen evolution.

[0054] The beneficial effects of this invention are as follows:

[0055] (1) This invention provides an energy-saving, economical, and scale-up automated method for selectively constructing hierarchical heterostructure electrocatalysts, transforming inexpensive iron-based alloy substrates into highly active and stable oxygen evolution reaction electrodes (i.e., hierarchical heterostructure electrocatalysts). This synthesis method involves an electrochemical reaction between iron with a low electrode potential and oxygen in an aqueous solution containing divalent nickel at room temperature. This process leads to the growth of thin-film nanosheets on the iron substrate. The nanosheet hierarchical heterostructure (i.e., the hierarchical heterostructure electrocatalyst) consists of iron-containing layered double hydroxides, rather than rust. This inexpensive and simple manufacturing process enables the iron-based derived electrode to achieve a speed of 10 mA / cm². 2 It exhibits good catalytic activity and active stability for more than 24 hours at a given current density.

[0056] (2) The method for selectively constructing hierarchical heterostructure electrocatalysts of the present invention has excellent gas dispersion capabilities, which may come from two aspects: (1) interconnected NiFe nanosheets form hierarchical mesopores (50-100 nm), which helps improve the wettability of the electrode surface and promotes the detachment of bubbles; (2) a binder-free electrodeposition method combined with in-situ automated galvanic cell reaction forms a firmly bonded FeW / NiFe-LDH electrocatalyst on a highly conductive nickel foam substrate, thereby minimizing the resistance generated by the contact between the electrocatalyst and the NF substrate. The FeW / NiFe-LDH electrocatalyst can drive the OER reaction at extremely low overpotential (240 mV) and has significant durability at high current densities.

[0057] (3) The bubbles generated during the OER process tend to accumulate on the planar substrate, resulting in significant bubble overpotential, especially under high current density and strong venting conditions. The multi-level heterostructure electrocatalyst constructed in this invention can significantly improve the desorption rate of bubbles, reduce the accumulation of bubbles on the surface, and reduce the overpotential of the electrocatalytic process.

[0058] (4) The method of the present invention automatically prepares a highly efficient and independent oxygen evolution electrode (i.e., a multi-level heterostructure electrocatalyst) by electrodepositing a FeW alloy layer on a conductive substrate and utilizing the spontaneous redox reaction of ions in solution without using a chemical binder.

[0059] (5) The multi-level heterostructure electrocatalyst prepared by the present invention is highly efficient and stable, has a wide range of applications, requires a wide range of materials, has a simple preparation process, is convenient, green and pollution-free, has a simple and easy-to-operate technical implementation process, is low in cost, and is easy to industrialize and promote. Attached Figure Description

[0060] Figure 1 X-ray diffraction pattern of the FeW alloy layer in Example 3

[0061] Figure 2 Scanning electron microscope image of the FeW / NiFe-LDH electrocatalyst in Example 2.

[0062] Figure 3 Scanning electron microscope image of the FeW / NiFe-LDH electrocatalyst in Example 2.

[0063] Figure 4 Linear sweep voltammetry curves of nickel foam and FeW / NiFe-LDH electrocatalytic oxygen evolution in Example 2.

[0064] Figure 5 Chronopotential stability test diagram of FeW / NiFe-LDH electrocatalytic oxygen evolution in Example 2. Detailed Implementation

[0065] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0066] Example 1

[0067] The present invention provides a multi-level heterostructure electrocatalyst, the specific process of which is as follows:

[0068] Step 1: Synthesis of the FeW alloy layer:

[0069] (1) Pretreatment of nickel foam: Cut copper foam into several pieces of 1×2cm size, and clean them with hydrochloric acid, deionized water and ethanol by ultrasonic cleaning for 5min respectively. After treatment, place them in ethanol solution for later use.

[0070] (2) Preparation of electrodeposition solution: The electrodeposition solution consists of 98.3 g / L FeCl2·4H2O and 17.6 g / L (NH4)6W7O. 24 ·6H2O, 58.7 g / L Na3C6H5O7·2H2O, 1.4 g / L potassium chloride, and adjust the pH of the electrodeposition solution to 4-5 using dilute acid;

[0071] (3) Deposition of FeW alloy layer: The pretreated foamed nickel is used as the cathode and the graphite rod is used as the anode. The anode and cathode are immersed in the electrodeposition solution, the temperature is controlled at 0 to 25°C, the voltage is controlled at 2 to 10V, and the deposition time is 2 to 10 min.

[0072] (4) After deposition, the sample is taken out and cleaned with deionized water and ethanol, and then dried to obtain nickel foam loaded with FeW alloy layer.

[0073] Step Two: The Automated Process of Selectively Constructing Multi-Level Heterogeneous Structures

[0074] (1) Dissolve 1.2g Ni(NO3)2·6H2O and 2g NaCl in 200mL of water and stir thoroughly to obtain a mixed solution;

[0075] (2) Immerse the nickel foam loaded with FeW alloy layer prepared in step one into the mixed solution, adjust the stirring speed, and keep it at 80°C for 1 hour;

[0076] (3) The FeW alloy layer that has undergone complete reaction is removed from the mixed solution, washed with deionized water and ethanol, and dried in a vacuum drying oven at 60°C for 4 hours to obtain a multi-level heterostructure electrocatalyst.

[0077] Example 2

[0078] The present invention provides a multi-level heterostructure electrocatalyst, the specific process of which is as follows:

[0079] Step 1: Synthesis of the FeW alloy layer:

[0080] (1) Pretreatment of nickel foam: Cut nickel foam into several pieces of 1×2cm size, and clean them with hydrochloric acid, deionized water and ethanol by ultrasonic cleaning for 5min respectively. After treatment, place them in ethanol solution for later use.

[0081] (2) Preparation of electrodeposition solution: The electrodeposition solution consists of 83.4 g / L FeSO4·7H2O and 16.5 g / L (NH4)6W7O. 24 The electrodeposition solution was prepared with 6H2O, 52.9 g / L Na3C6H5O7·2H2O, and 1.4 g / L K2SO4, and the pH of the solution was adjusted to 4-5 using dilute acid.

[0082] (3) Deposition of FeW alloy layer: The pretreated foamed nickel is used as the cathode and the graphite rod is used as the anode. The anode and cathode are immersed in the electrodeposition solution, the temperature is controlled at 0 to 25°C, the voltage is controlled at 2 to 10V, and the deposition time is 2 to 10 min.

[0083] (4) After deposition, the sample is taken out and cleaned with deionized water and ethanol, and then dried to obtain nickel foam loaded with FeW alloy layer.

[0084] Step Two: The Automated Process of Selectively Constructing Multi-Level Heterogeneous Structures

[0085] (1) Dissolve 2.38g NiCl2·6H2O and 5.84g NaCl in 200mL of water and stir thoroughly to obtain a mixed solution;

[0086] (2) Immerse the FeW alloy layer prepared in step one into the mixed solution, adjust the stirring speed, and keep it at 30°C for 4 hours;

[0087] (3) The FeW alloy layer that has been completely reacted is taken out from the mixed solution, washed with deionized water and ethanol, and dried in a vacuum drying oven at 60°C for 4 hours to obtain a multi-level heterostructure electrocatalyst.

[0088] Example 3

[0089] The present invention provides a multi-level heterostructure electrocatalyst, the specific process of which is as follows:

[0090] Step 1: Synthesis of the FeW alloy layer:

[0091] (1) Carbon cloth pretreatment: Several pieces of carbon cloth were cut into 1×2cm size, and then ultrasonically cleaned with acetone, ethanol and deionized water for 10min in sequence. Then the carbon cloth was placed in a reflux device containing concentrated nitric acid and refluxed at 100℃ for 1h. After that, the carbon cloth was taken out and washed with a large amount of ultrapure water until neutral. After the carbon cloth was cleaned, it was placed in a vacuum drying oven and dried at 60~80℃. Finally, acid-impregnated hydrophilic modified carbon cloth was obtained.

[0092] (2) Preparation of electrodeposition solution: The electrodeposition solution consists of 58.5 g / L FeC2O4 and 11.6 g / L (NH4)6W7O 24 • 6H2O, 40 g / L Na3C6H5O7·2H2O, 1.4 g / L NaCl, and adjust the pH of the electrodeposition solution to 4-5 using dilute acid;

[0093] (3) Deposition of nanoarray: The pretreated carbon cloth is used as the cathode and the graphite rod is used as the anode. The anode and cathode are immersed in the electrodeposition solution, the temperature is controlled at 0 to 25°C, the voltage is controlled at 2 to 10V, and the deposition time is 2 to 10 min.

[0094] (4) After deposition, the sample is taken out and cleaned with deionized water and ethanol, then dried. The FeW alloy layer loaded with conductive carbon cloth is obtained after drying.

[0095] Step Two: The Automated Process of Selectively Constructing Multi-Level Heterogeneous Structures

[0096] (1) Dissolve 4.75g NiSO4·6H2O and 8g NaCl in 200mL of water and stir thoroughly to obtain a mixed solution;

[0097] (2) Immerse the FeW alloy layer prepared in step one into the mixed solution, adjust the stirring speed, and keep it at 25°C for 12 hours;

[0098] (3) The FeW alloy layer that has undergone complete reaction is removed from the mixed solution, washed with deionized water and ethanol, and dried in a vacuum drying oven at 60°C for 4 hours to obtain a multi-level heterostructure electrocatalyst.

[0099] Performance testing:

[0100] The electrochemical oxygen evolution performance (OER) test in this patent was conducted using a CHI 760 electrochemical workstation (Shanghai Chenhua Instrument Co., Ltd.) and a standard three-electrode system. The auxiliary electrode was a graphite rod electrode, the reference electrode was a Hg / HgO electrode, and the working electrode was a FeW / NiFe-LDH electrode or a conductive substrate NF. The electrolyte was a 1 mol / L KOH solution. All potentials in the electrochemical tests were converted to RHE using the formula E(RHE) = E(vs.Hg / HgO) + 0.924V. The OER activity of the oxygen evolution electrode was evaluated using linear sweep voltammetry (LSV). The LSV potential range for the electrode OER performance was 1.2V–1.7V (vs.RHE), with a scan rate of 5 mV / s. The electrode stability was tested using a multi-segment chronopotential method.

[0101] like Figure 1 As shown, to avoid interference from the strong diffraction peaks of nickel foam, an FeW alloy layer was deposited on conductive carbon cloth and compared with the standard PDF card. It was found that it matched well with the standard card of Fe (PDF#06-0696), and no obvious characteristic peaks of W were detected, indicating that its crystallinity was poor, which may be due to the formation of alloy by W in the form of doping.

[0102] Image 3 shows that ultrathin NiFe-LDH nanosheets formed on the surface of the FeW alloy, creating a hierarchical multi-level heterostructure. The NiFe layered bimetallic hydroxide nanosheets exhibit a sheet-like structure with a size of approximately 500 nm. These nanosheets are 5-10 nm thick, indicating that they are ultrathin.

[0103] In summary, the FeW / NiFe-LDH electrocatalyst prepared by this invention has a unique multi-level heterogeneous structure composed of intersecting nanosheets. This special morphology gives it a large specific surface area, exposes more active sites, which is beneficial for gas evolution during the catalytic process and thus promotes water electrolysis. It also exhibits excellent electrocatalytic performance in alkaline solutions.

[0104] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A multi-level heterogeneous electrocatalyst, characterized in that, The multi-level heterostructure electrocatalyst comprises an iron-containing layered double hydroxide, wherein the iron-containing layered double hydroxide comprises NiFe nanosheets and a conductive substrate; the conductive substrate is supported with an FeW alloy layer; the NiFe nanosheets are wrapped around the surface of the conductive substrate; the NiFe nanosheets are interleaved. The loading of the FeW alloy layer on the conductive substrate is 10-15 mg / cm². 2 ; The multi-level heterostructure electrocatalyst is prepared by a method comprising the following steps: A conductive substrate loaded with FeW alloy layer is immersed in a mixed solution of nickel salt and chloride salt for reaction, followed by post-treatment to obtain a multi-level heterostructure electrocatalyst. The chloride salt includes at least one of sodium chloride, potassium chloride, and ammonium chloride; the concentration of the chloride salt is 10 g / L-40 g / L.

2. The multi-level heterostructure electrocatalyst according to claim 1, characterized in that: The thickness of the NiFe nanosheets is 5-10 nm.

3. The method for preparing the multi-level heterostructure electrocatalyst according to claim 1 or 2, characterized in that: Includes the following steps: A conductive substrate loaded with FeW alloy layers is immersed in a mixed solution of nickel and chloride salts for reaction, followed by post-treatment to obtain a multi-level heterostructure electrocatalyst.

4. The method for preparing the multi-level heterostructure electrocatalyst according to claim 3, characterized in that: The reaction temperature is 25 ℃-80 ℃; the reaction time is 1 h-12 h.

5. The method for preparing the multi-level heterostructure electrocatalyst according to claim 3, characterized in that: The nickel salt includes at least one of nickel sulfate, nickel nitrate, and nickel chloride; the concentration of the nickel salt is 5 g / L-24 g / L.

6. The method for preparing the multi-level heterostructure electrocatalyst according to claim 3, characterized in that: The preparation of the FeW alloy layer loaded on the conductive substrate includes the following steps: Using a conductive substrate as the cathode and a graphite rod as the anode, the cathode and anode are immersed in an electrodeposition solution for deposition and purification to obtain a conductive substrate loaded with an FeW alloy layer. The electrodeposition solution comprises iron salts and tungstates.

7. The method for preparing the multi-level heterostructure electrocatalyst according to claim 6, characterized in that: The electrodeposition solution has a pH of 4-5; the iron salt includes at least one of ferrous chloride, ferrous oxalate, and ferrous carbonate; the concentration of the iron salt is 50-100 g / L; the tungstate includes Na₂WO₄·2H₂O and (NH₄)₆W₇O. 24 At least one of ·6H2O; the concentration of the tungstate is 10-18 g / L.

8. The method for preparing the multi-level heterostructure electrocatalyst according to claim 6, characterized in that: The deposition temperature is 0~25 ℃, the deposition voltage is 2~10 V, and the deposition time is 2~10 min.

9. The application of the multi-level heterostructure electrocatalyst according to claim 1 or 2 in electrocatalytic oxygen evolution.

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