Methods and applications for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam

Abstract

This invention provides a method and application for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam, belonging to the field of nanomaterial synthesis technology. The method includes the following steps: dissolving thioacetamide, sodium molybdate, and nickel nitrate in deionized water and stirring thoroughly until completely dissolved to obtain a mixed reaction solution; transferring the mixed reaction solution to a high-pressure reactor, then adding iron foam as a Fe source and framework, and heating and maintaining the temperature until the reaction is complete; after the high-pressure reactor cools to room temperature, removing the iron foam, and washing and drying it to obtain Ni-Fe7S8 / MoS2 heterojunction nanomaterials. This invention solves the problems of high raw material cost, difficult synthesis, and poor electrode stability by using a one-step hydrothermal method to grow Ni-doped Fe7S8 / MoS2 heterojunction nanomaterials in situ on iron foam, achieving low-cost and high-efficiency synthesis, improving electrode stability, and obtaining excellent catalytic performance with low overpotential, fast kinetics, and high charge transfer rate in electrochemical catalytic water splitting to produce hydrogen.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial synthesis technology, and in particular to a method and application for the in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam. Background Technology

[0002] Due to increased energy consumption and environmental pollution, traditional energy sources will inevitably be replaced by more environmentally friendly new energy sources. Hydrogen energy, as an important secondary energy source, has attracted much attention due to its many advantages, such as abundant sources, cleanliness and environmental friendliness, high calorific value, diverse utilization forms, and wide range of applications. It is regarded as the most promising clean energy source in the 21st century.

[0003] Currently, the main hydrogen production routes include hydrogen production from traditional fossil fuels and hydrogen production from renewable energy sources such as water, solar, wind, and biomass. Hydrogen production via water electrolysis is the most environmentally friendly process, producing no pollution and possessing broad development prospects. Water electrolysis alters the redox potential of water through electrolysis, causing it to decompose and produce O2 and H2. At room temperature, the overall reaction equation for water electrolysis is 2H2O + electricity → 2H2 + O2. This process consists of two half-reactions: the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). At room temperature and standard atmospheric pressure, the minimum theoretical voltage required to drive both the HER and OER reactions is 1.23V, ΔG = 274.2 kJ / mol; therefore, additional energy is required for the reactions to occur. The cathodic HER is a relatively easy two-electron process that can proceed at low overpotentials. However, the anodic OER, acting as an electron donor for the HER, is a more complex four-electron process with slow kinetics, requiring higher overpotentials to drive the reaction. This limits the overall water electrolysis efficiency, severely hindering its practical application. Therefore, developing new strategies to obtain high-performance OER catalysts remains one of the most important tasks in the field of water electrolysis research. Noble metal-based materials (such as iridium / ruthenium oxide) are the most efficient OER electrocatalysts. However, their high cost and low abundance limit their application.

[0004] Furthermore, the low price of non-precious metals makes their development and utilization more advantageous. Transition metal sulfides (TMDs) can exhibit different phases: 1T (tetragonal), 2H (hexagonal), and 3R (triangular lattice). They also possess a unique graphite-like layered structure, offering greater morphological flexibility and better integration with dopants. In addition, TMDs have multiple synthetic methods. Therefore, TMDs are expected to play an important role in the field of electrocatalysis. MoS2, in particular, possesses a unique two-dimensional structure, multiple crystalline phases, and the ability to interconvert. Its semiconductor-like 2H phase can be chemically synthesized into a metastable 1T phase, improving catalytic performance. Therefore, it is considered a promising catalyst. Compared to other transition metal sulfides, iron-based sulfides have significant advantages. First, iron sulfide is the most widely distributed sulfide in the Earth's crust, forming in various geological structures. Second, iron is the cheapest among non-precious metals. Third, iron-sulfur clusters are catalytically active sites for some chemical reactions, such as proton reduction and nitrogen reduction. Therefore, iron-based sulfides are frequently used in catalyst synthesis.

[0005] To further enhance the activity of electrocatalysts, constructing heterogeneous interfaces to increase material defects, enhance active sites, and optimize intermediate adsorption and desorption has been considered an effective strategy for electrocatalyst preparation. Qi et al. successfully designed and prepared independent, defect-rich heterogeneous MoS2 / NiS2 nanosheets and used them as bifunctional electrocatalysts for bulk water splitting. The resulting MoS2 / NiS2 interfaces possess abundant defects and a disordered structure, which can modify electronic interactions, promote electron movement, and benefit electrocatalytic reactions. Elemental doping can induce phase transitions and alter electron density, and is also a commonly used catalyst preparation strategy. Zhu et al. investigated a magnetohydrothermal synthesis method for W-doped MoS2 with environmental stability and a high concentration of 1T phase. The prepared molybdenum disulfide had a 1T phase ratio as high as 80%, environmental stability of over one year, and excellent HER performance. Combining heterogeneous interface construction and elemental doping can further regulate the electron cloud density of the heterogeneous interface, thereby improving catalytic activity. Ge et al. developed a bifunctional electrocatalyst, Co-FeS / MoS2, using a simple two-step solvothermal method. The prepared catalyst inherited the structural characteristics of the original MOF, maintaining a large surface area and abundant active sites. Furthermore, Co doping induced a redistribution of the electric field at the FeS and MoS2 heterojunction interface, optimizing the adsorption capacity of reaction intermediates and thus exhibiting excellent electrocatalytic activity. This study demonstrates that the simultaneous application of heterostructure and doping techniques can effectively improve the OER performance of the catalyst. Despite these advancements, the methods for synthesizing catalysts remain complex, often involving two or even multiple steps, which are time-consuming, have poor reproducibility, and easily lead to raw material waste and increased costs. Moreover, the synthesized powdered electrocatalysts require binders such as Nafion to be supported on conductive electrodes. Due to the large amount of gas generated on the electrode surface during water electrolysis, the catalyst is prone to detachment, making it difficult to achieve stable catalysis with high current and long duration. Therefore, preparing high-performance transition metal-based heterojunction nanomaterial electrocatalysts for water splitting using simplified catalyst synthesis routes is a significant but challenging endeavor.

[0006] In summary, existing technologies have several defects and shortcomings, specifically: precious metal-based catalysts are not suitable for large-scale production due to their high price and limited reserves; the synthesis routes of electrocatalysts are too complex, production is time-consuming and labor-intensive, reproducibility is poor, and raw materials are easily wasted; electrocatalysts often require binders such as Nafion to be supported on conductive electrodes, resulting in poor stability. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a method and application for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam. By using a one-step hydrothermal method to grow Ni-doped Fe7S8 / MoS2 heterojunction nanomaterials in situ on iron foam, the problems of high raw material cost, difficult synthesis, and poor electrode stability are solved, achieving low-cost and high-efficiency synthesis, improving electrode stability, and obtaining excellent catalytic performance with low overpotential, fast kinetics, and high charge transfer rate in electrochemical catalytic water splitting to produce hydrogen.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] One objective of this invention is to provide a method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam, comprising the following steps:

[0010] S1. Dissolve thioacetamide, sodium molybdate and nickel nitrate in deionized water and stir thoroughly with a magnetic stirrer until completely dissolved to obtain a mixed reaction solution.

[0011] S2. Transfer the mixed reaction solution to a high-pressure reactor, then add pretreated iron foam as the Fe source and as the framework, and heat and keep warm until the reaction is complete.

[0012] S3. After the high-pressure reactor cools to room temperature, remove the iron foam, wash and dry it to obtain Ni-Fe7S8 / MoS2 heterojunction nanomaterials.

[0013] Preferably, in step S1, the mass of the thioacetamide is 125-250 mg, the mass of the sodium molybdate is 81-162 mg, the molar ratio of the sodium molybdate to the thioacetamide is 1:5; the mass of the nickel nitrate is 5-20 mg, the volume of the deionized water is 30-60 mL, and the ratio of the sodium molybdate to the deionized water, in g:mL, is 81:35000.

[0014] Preferably, in step S2, the pretreatment process of the iron foam is as follows: the iron foam is washed sequentially with hydrochloric acid, deionized water, and ethanol, and finally dried; the specifications of the iron foam are 4cm*1cm*0.1cm to 6cm*3cm*0.1cm, and the iron foam and sodium molybdate are separated by a distance of cm. 3 The ratio is 4:3, expressed as mmol / L.

[0015] Preferably, in step S2, the heating and heat preservation involves transferring the high-pressure reactor to a heating device and heating it to 150–230°C for 12–24 hours.

[0016] Preferably, in step S3, the process of washing and drying the iron foam is as follows: the iron foam is taken out from the high-pressure reactor, then washed several times alternately with deionized water and anhydrous ethanol, and finally placed in a vacuum drying oven to dry for 8-12 hours.

[0017] The second objective of this invention is to provide a Ni-Fe7S8 / MoS2 heterojunction nanomaterial prepared by the above method.

[0018] The third objective of this invention is to provide an electrode prepared from Ni-Fe7S8 / MoS2 heterojunction nanomaterials obtained by the above method.

[0019] The fourth objective of this invention is to provide a battery prepared using Ni-Fe7S8 / MoS2 heterojunction nanomaterials obtained by the above method.

[0020] The fifth objective of this invention is to provide a catalyst prepared by the above method.

[0021] The sixth objective of this invention is to provide an application of the Ni-Fe7S8 / MoS2 heterojunction nanomaterial prepared by the above method in the electrochemical catalytic splitting of water to produce hydrogen.

[0022] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] (1) In terms of raw material selection, the present invention uses Mo and Fe-based materials that are abundant on Earth as raw materials. They are inexpensive and easy to obtain, and have a significant cost advantage compared with the use of precious metal-based catalysts.

[0024] (2) The present invention synthesizes catalysts by a one-step hydrothermal method, which is simple to operate compared with the multi-step method, can significantly shorten the production time, reduce raw material loss, and has good repeatability, thus reducing the complexity and cost of production.

[0025] (3) This invention utilizes iron foam directly as an iron source and conductive electrode, improving conductivity, avoiding the need for additional iron sources, and saving raw materials; the Fe7S8 generated by sulfidation has good OER performance and can effectively induce efficient OER catalytic activity; at the same time, it avoids the use of binders such as Nafion, improving electrode stability, enabling it to stably catalyze for a long time at a large current density, and exhibiting excellent performance in electrochemical catalytic water splitting to produce hydrogen, such as at 100 mA / cm 2 The overpotential is as low as 260.1 mV at current density, the Tafel slope is low, and the charge transfer rate is fast. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam according to the present invention;

[0028] Figure 2 SEM images of the Ni-Fe7S8 / MoS2 heterojunction nanomaterials provided by this invention;

[0029] Figure 3 The sample morphology of the Ni-Fe7S8 / MoS2 heterojunction nanomaterial provided by the present invention is a nanoflower pattern supported on nanosheets.

[0030] Figure 4 This is a comparison of the electrochemical performance of the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared in Examples 1-3 of this invention;

[0031] Figure 5 The Tafel slope comparison diagrams of Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared in Examples 1-3 of this invention are shown.

[0032] Figure 6 The image shows a comparison of impedance (EIS) of the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared in Examples 1-3 of this invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, this invention provides a method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam, comprising the following steps:

[0036] S1. Dissolve thioacetamide, sodium molybdate and nickel nitrate in deionized water and stir thoroughly with a magnetic stirrer until completely dissolved to obtain a mixed reaction solution.

[0037] S2. Transfer the mixed reaction solution to a high-pressure reactor, then add iron foam as the Fe source and as the framework, and heat and keep warm until the reaction is complete;

[0038] S3. After the high-pressure reactor cools to room temperature, remove the iron foam, wash and dry it to obtain Ni-Fe7S8 / MoS2 heterojunction nanomaterials.

[0039] In step S1, the mass of the thioacetamide is 125-250 mg, the mass of the sodium molybdate is 81-162 mg, and the molar ratio of sodium molybdate to thioacetamide is 1:5; the mass of the nickel nitrate is 5-20 mg, the volume of the deionized water is 30-60 mL, and the ratio of sodium molybdate to deionized water (g:mL) is 81:35000.

[0040] In step S2, the iron foam has dimensions of 4cm*1cm*0.1cm to 6cm*3cm*0.1cm, and the iron foam and sodium molybdate are separated by a ratio of cm. 3 The ratio of mmol to 4:3 is used. The heating and heat preservation involves transferring the high-pressure reactor to a heating device and heating it to 150–230°C for 12–24 hours.

[0041] In step S3, the process of washing and drying the iron foam is as follows: the iron foam is taken out from the high-pressure reactor, then washed several times alternately with deionized water and anhydrous ethanol, and finally placed in a vacuum drying oven to dry for 8-12 hours.

[0042] Figure 2 The SEM image of the Ni-Fe7S8 / MoS2 heterojunction nanomaterial provided by this invention is shown below. Figure 2 It can be seen that the Ni-Fe7S8 / MoS2 heterostructure nanomaterial has a uniform microstructure. Figure 3 The sample morphology of the Ni-Fe7S8 / MoS2 heterojunction nanomaterial provided by this invention is a nanoflower pattern supported on nanosheets, as shown in the reference. Figure 3 It can be seen that the morphology of the Ni-Fe7S8 / MoS2 heterojunction nanomaterial is a structure of nanoflowers loaded on nanosheets.

[0043] As one possible implementation of the present invention, the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the above method can be used to prepare electrodes.

[0044] As one possible implementation of the present invention, the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the above method can be used to prepare batteries.

[0045] As one possible implementation of the present invention, the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the above method can be used to prepare catalysts.

[0046] As one possible implementation of the present invention, the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the above method can be used in the electrochemical catalytic water splitting to produce hydrogen.

[0047] The technical solution of the present invention will be further described below through specific embodiments.

[0048] Example 1

[0049] In this embodiment, the preparation method of Ni-Fe7S8 / MoS2 heterojunction nanomaterials is as follows: First, 81 mg of sodium molybdate, 125 mg of thioacetamide, and 5 mg of nickel nitrate are weighed and 35 mL of deionized water is added. The mixture is stirred for 30 min at room temperature using a magnetic stirrer to obtain a mixed reaction solution. Then, the thoroughly stirred mixed reaction solution is transferred to a Teflon-lined stainless steel high-pressure reactor, and iron foam pretreated with hydrochloric acid, deionized water, and ethanol and dried is added. The iron foam has dimensions of 4.4 cm * 1 cm * 0.1 cm. The stainless steel high-pressure reactor is then placed in an oven and maintained at 200°C for 18 h. Finally, after cooling to room temperature, the reacted iron foam is removed, at which point a uniform black product covers the surface of the iron foam. The iron foam is then washed several times alternately with deionized water and ethanol, and then dried in a vacuum drying oven at 60°C for 12 h. The resulting product is Ni-Fe7S8 / MoS2 heterojunction nanomaterials, where the Ni:Mo molar ratio is 1:20.

[0050] Example 2

[0051] In this embodiment, the preparation process of Ni-Fe7S8 / MoS2 heterojunction nanomaterials is as follows: First, 81 mg of sodium molybdate, 125 mg of thioacetamide, and 10 mg of nickel nitrate are weighed and 35 mL of deionized water is added. The mixture is stirred for 30 min at room temperature using a magnetic stirrer to obtain a mixed reaction solution. Then, the thoroughly stirred mixed reaction solution is transferred to a Teflon-lined stainless steel high-pressure reactor, and iron foam pretreated with hydrochloric acid, deionized water, and ethanol and dried is added. The iron foam has dimensions of 4.4 cm * 1 cm * 0.1 cm. The stainless steel high-pressure reactor is then placed in an oven and maintained at 200°C for 18 h. Finally, after cooling to room temperature, the reacted iron foam is removed, at which point a uniform black product covers the surface of the iron foam. Finally, the iron foam was washed several times with deionized water and ethanol alternately, and then dried in a vacuum drying oven at 60°C for 12 hours. The product obtained was Ni-Fe7S8 / MoS2 heterojunction nanomaterial, in which the molar ratio of Ni:Mo was 1:10.

[0052] Example 3

[0053] In this embodiment, the preparation method of Ni-Fe7S8 / MoS2 heterojunction nanomaterials is as follows: First, 81 mg of sodium molybdate, 125 mg of thioacetamide, and 20 mg of nickel nitrate were weighed and 35 mL of deionized water was added. The mixture was stirred for 30 min at room temperature using a magnetic stirrer to obtain a mixed reaction solution. Then, the thoroughly stirred mixed reaction solution was transferred to a Teflon-lined stainless steel high-pressure reactor, and iron foam pretreated with hydrochloric acid, deionized water, and ethanol and dried was added. The iron foam had dimensions of 4.4 cm * 1 cm * 0.1 cm. The stainless steel high-pressure reactor was then placed in an oven and maintained at 200 °C for 18 h. Finally, after cooling to room temperature, the reacted iron foam was removed, at which point a uniform black product covered the surface of the iron foam. The iron foam was then washed several times alternately with deionized water and ethanol, and then dried in a vacuum drying oven at 60 °C for 12 h. The resulting product was Ni-Fe7S8 / MoS2 heterojunction nanomaterials, wherein the molar ratio of Ni:Mo was 1:5.

[0054] Example 4

[0055] The three products prepared according to Examples 1-3 were subjected to electrochemical testing in 1.0 M KOH at room temperature using a standard three-electrode electrochemical workstation. The working electrode on the iron-in-iron (IF) electrode was made of Ni-Fe7S8 / MoS2@IF. Calibration was performed with reference to a standard electrode, and the electrode was converted to a reversible hydrogen electrode (RHE) using a formula.

[0056] E RHE =E (Hg / HgO)+0.89;

[0057] Prior to each OER test, the three-electrode system was bubbled with high-purity oxygen for 30 minutes. To explore OER activity, linear sweep voltammetry was performed at a rate of 5 mV / s over a voltage range of 0 V to 1.8 V. EIS measurements were taken from 0.01 to 10 mV. 5 The frequency range was obtained in Hz and fitted using Zview software. A Hg / HgO electrode in 1M KOH aqueous solution was used as a reference electrode.

[0058] After completing the above electrochemical tests, the test data were analyzed, and the results are as follows: Figures 4-6 As shown. From Figure 4 A comparison of the performance of the Ni-Fe7S8 / MoS2 heterostructure nanomaterials prepared in Examples 1, 2, and 3 shows that the catalyst prepared with 10 mg of nickel nitrate (Ni:Mo molar ratio of 1:10) exhibits better electrochemical performance than those prepared with 5 mg of nickel nitrate (Ni:Mo molar ratio of 1:20) and 20 mg of nickel nitrate (Ni:Mo molar ratio of 1:5). This is particularly evident at 100 mA / cm². 2 At a current density of 260.1 mV, the catalyst exhibits excellent electrochemical performance with an overpotential of only 260.1 mV. Figure 5 The image shows a comparison of the Tafel slopes of the Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared in Examples 1, 2, and 3. The comparison reveals that the Tafel slope is lowest when 10 mg of nickel nitrate is added, i.e., the Ni:Mo molar ratio is 1:10. This indicates that the catalyst exhibits faster kinetics during the reaction and can more efficiently promote the reaction. (Further details omitted). Figure 6 Impedance diagrams of the catalysts obtained in different embodiments show that the catalyst prepared in Example 2 has the lowest impedance. This means that in the electrochemical reaction, the catalyst of Example 2 has a faster charge transfer rate, enabling more rapid electron transfer and further improving catalytic efficiency. In summary... Figures 4-6 The results fully demonstrate the advantages of the catalyst prepared by adding 10 mg of nickel nitrate in electrochemical catalytic performance when preparing Ni-Fe7S8 / MoS2 heterojunction nanomaterials, and also provide an important basis for the optimization of this material in practical applications.

[0059] pass Figures 4-6 The electrochemical properties, Tafel slope, and impedance of the Ni-Fe7S8 / MoS2 heterostructure nanomaterials prepared in Examples 1, 2, and 3 were compared and analyzed, clearly demonstrating the effect of different nickel nitrate addition amounts on the material properties. To more clearly and comprehensively illustrate these performance differences, specific data are summarized in Table 1. Table 1 records the electrochemical properties of the materials at 100 mA / cm² under different Ni:Mo molar ratios. 2Key performance indicators such as overpotential and Tafel slope at current density. See Table 1:

[0060] Table 1 Performance Comparison Data

[0061]

[0062] Table 1 shows that the Ni-Fe7S8 / MoS2 heterostructure nanomaterials prepared with the addition of 10 mg of nickel nitrate, i.e., a Ni:Mo molar ratio of 1:10, exhibit superior performance in various aspects. This is consistent with... Figures 4-6 The trends reflected are completely consistent, further providing strong data support for the performance research and application of the prepared Ni-Fe7S8 / MoS2 heterostructure nanomaterials.

[0063] Therefore, the above-mentioned method and application for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam solves the problems of high raw material cost, difficult synthesis and poor electrode stability by using a one-step hydrothermal method to grow Ni-doped Fe7S8 / MoS2 heterojunction nanomaterials in situ on iron foam. It achieves low-cost and high-efficiency synthesis, improves electrode stability, and obtains excellent catalytic performance with low overpotential, fast kinetics and high charge transfer rate in electrochemical catalytic water splitting to produce hydrogen.

[0064] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0065] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam, characterized in that, Includes the following steps: S1. Dissolve thioacetamide, sodium molybdate and nickel nitrate in deionized water and stir thoroughly with a magnetic stirrer until completely dissolved to obtain a mixed reaction solution. S2. Transfer the mixed reaction solution to a high-pressure reactor, then add pretreated iron foam as the Fe source and as the framework, and heat and keep warm until the reaction is complete. S3. After the high-pressure reactor cools to room temperature, remove the iron foam, wash and dry it to obtain Ni-Fe7S8 / MoS2 heterojunction nanomaterials.

2. The method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam according to claim 1, characterized in that, In step S1, the mass of the thioacetamide is 125-250 mg, the mass of the sodium molybdate is 81-162 mg, and the molar ratio of sodium molybdate to thioacetamide is 1:5; the mass of the nickel nitrate is 5-20 mg, the volume of the deionized water is 30-60 mL, and the ratio of sodium molybdate to deionized water, in g:mL, is 81:35000.

3. The method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam according to claim 1, characterized in that, In step S2, the pretreatment process of the iron foam is as follows: the iron foam is washed sequentially with hydrochloric acid, deionized water, and ethanol, and finally dried; the size of the iron foam is 4cm*1cm*0.1cm to 6cm*3cm*0.1cm, and the iron foam and sodium molybdate are separated by a distance of cm. 3 The ratio is 4:3, expressed as mmol / L.

4. The method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam according to claim 3, characterized in that, In step S2, the heating and heat preservation involves transferring the high-pressure reactor to a heating device and heating it to 150-230°C for 12-24 hours.

5. The method for in-situ preparation of Ni-Fe7S8 / MoS2 heterostructure nanomaterials based on iron foam according to claim 1, characterized in that, In step S3, the process of washing and drying the iron foam is as follows: the iron foam is taken out from the high-pressure reactor, then washed several times alternately with deionized water and anhydrous ethanol, and finally placed in a vacuum drying oven to dry for 8-12 hours.

6. A Ni-Fe7S8 / MoS2 heterojunction nanomaterial prepared by the method for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam as described in any one of claims 1 to 5.

7. An electrode prepared from Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the method for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam as described in claim 6.

8. A battery prepared from Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the method for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam as described in claim 6.

9. A catalyst prepared by the method for in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam as described in any one of claims 1 to 5.

10. The application of Ni-Fe7S8 / MoS2 heterojunction nanomaterials prepared by the method of in-situ preparation of Ni-Fe7S8 / MoS2 heterojunction nanomaterials based on iron foam as described in any one of claims 1 to 5 in the electrochemical catalytic splitting of water to produce hydrogen.

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