A molybdenum oxide-nickel sulfide heterostructure nanometer array electrocatalyst and a preparation method thereof

Abstract

The application provides a preparation method of a molybdenum oxide-nickel sulfide heterostructure nanometer array electrocatalyst, and comprises the following steps: 1) preparing a nickel foam (NF) substrate; 2) preparing a homogeneous solution of thiourea and (NH4)6Mo7O 24 ·4H2O in a molar ratio of 10-20:1; 3) dissolving the thiourea and (NH4)6Mo7O 24 ·4H2O in deionized water to obtain a homogeneous solution after stirring; and 4) reacting the nickel foam substrate prepared in the step 1 with the homogeneous solution prepared in the step 2 to obtain a MoO x -Ni3S2 / NF heterostructure nanometer array sample. The technical scheme of the application can greatly improve the conductivity and catalytic efficiency of the catalyst and reduce the manufacturing cost.

Description

Technical Field

[0001] This invention belongs to the field of energy conversion technology, specifically relating to a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst and its preparation method. Background Technology

[0002] In the search for new energy alternatives, hydrogen energy, as a highly efficient, clean, and ideal secondary energy source, has received widespread attention. Hydrogen electrolysis (HER) technology is one of the important methods for developing and utilizing hydrogen energy. It boasts high energy efficiency and produces no harmful pollutants, making it a very clean and environmentally friendly hydrogen production method. Hydrogen electrolysis also ensures zero carbon emissions, meeting environmental requirements after direct combustion. Alkaline electrolyzer systems are advantageous for producing high-yield, high-purity hydrogen, offering the advantage of long-term stable operation and suitability for large-scale development. However, the kinetics of the HER reaction in alkaline electrolytes are much slower than in acidic electrolytes, hindering the further industrial development of alkaline HER. Therefore, developing efficient and robust HER electrocatalysts to reduce overpotential in alkaline media is of great significance for electrochemical water splitting.

[0003] In existing technologies, platinum-based catalysts, represented by commercial platinum-carbon catalysts, are the most ideal catalysts for the HER reaction. Although platinum-based catalysts possess high performance, their scarcity and high cost severely limit their widespread application in industrial catalysis. Therefore, designing and developing electrolytic hydrogen production catalysts with good catalytic activity using non-precious metal materials is of great significance.

[0004] In recent years, transition metal dihalogens (TMDs) such as WS2, MoS2, MoSe2, and Ni3S2 have attracted considerable attention for water electrolysis, among which Ni sulfides (such as NiS, NiS2, and Ni3S2) have garnered significant interest due to their low cost and ease of fabrication. Ni3S2 stands out due to its inherent Ni-Ni metal network structure, which endows it with metalloid conductivity and excellent intrinsic catalytic activity. However, its catalytic activity remains lower than that of noble metals, thus requiring further research into the efficient water splitting of Ni3S2-based catalysts. Summary of the Invention

[0005] A brief overview of this disclosure is provided below to offer a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of the disclosure. It is not intended to identify key or essential parts of the disclosure, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] The present invention aims to provide a molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst material and its preparation method. Molybdenum oxide nanospheres are epitaxially grown on the surface of nickel sulfide. At the interface, strong electron interactions and lattice distortion create more catalytically active sites. By controlling the loading of molybdenum oxide nanospheres on the nickel sulfide surface, more interfaces with active sites are exposed to participate in the catalytic reaction. Nickel sulfide is designed as a single-crystal rod-shaped nanoarray structure grown on a nickel mesh. While increasing the active area, the grain-bound single-crystal nickel sulfide nanorods provide a "highway" for electrons, allowing them to reach the active sites at the molybdenum oxide-nickel sulfide heterostructure interface more easily and quickly, thereby improving catalytic efficiency and achieving better hydrogen evolution performance.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A method for preparing a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst is provided, comprising the following steps:

[0009] 1) Preparation of nickel foam (NF) substrate;

[0010] 2) Preparation of thiourea and (NH4)6Mo7O 24 A homogeneous solution of 4H2O was prepared by weighing out thiourea and (NH4)6Mo7O in a molar ratio of 10-20:1. 24 ·4H2O, dissolved in deionized water, and stirred to obtain a homogeneous solution;

[0011] 3) React the nickel foam substrate prepared in step 1 with the homogeneous solution prepared in step 2 to obtain MoO. x -Ni3S2 / NF heterostructure nanoarray sample.

[0012] Furthermore, it also includes step 4:

[0013] 4) Wash the sample obtained in step 3 repeatedly and then dry it.

[0014] Furthermore, in step 1, the nickel foam substrate is ultrasonically treated in 1-5 mol / L hydrochloric acid for 5-20 min to remove the surface oxide layer; the treated nickel foam substrate is ultrasonically cleaned with anhydrous ethanol and deionized water sequentially for 10-40 min, and then vacuum dried at 40-70℃ for 3-8 h.

[0015] Furthermore, in step 2, 1.5 mmol of thiourea and 0.1 mmol of (NH4)6Mo7O are weighed out. 24 Dissolve 4H2O in 25 ml of deionized water and stir magnetically for 30 min to obtain a homogeneous solution.

[0016] Furthermore, in step 3, the homogeneous solution from step 2 is transferred to a high-pressure reactor lined with polytetrafluoroethylene, a piece of nickel foam substrate prepared in step 1 is placed in the solution, and the reactor is heated in a constant temperature drying oven at 180-220℃ for 8-15 hours.

[0017] Furthermore, in step 4, the sample prepared in step 3 is washed 3-6 times with deionized water and anhydrous ethanol, respectively. The washed sample is then vacuum dried at 40-80℃ for 8-15 hours to obtain MoO. x -Ni3S2 / NF.

[0018] The present invention also provides a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material prepared according to any of the above preparation methods.

[0019] Furthermore, the catalyst material is an array of nanorods covered with nanospheres, grown on the surface of a nickel foam substrate, wherein the nanospheres are MoO. x The nanorods are made of Ni3S2, the nanospheres have a radius of 30-100 nm, the nanorods have a diameter of 100-500 nm, and the length is 2.2-7.4 μm.

[0020] The present invention also provides an application of the above-mentioned molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material as a catalyst for hydrogen production by water electrolysis.

[0021] Compared with existing catalytic materials, the beneficial effects of this invention are:

[0022] By constructing a special one-dimensional nickel sulfide nanorod-molybdenum oxide nanosphere heterostructure array nanocatalyst, the active area is increased, and the interface has more highly active sites due to electron transfer and lattice distortion. The nanospheres grow on the surface of the nanorods but do not completely cover the nickel sulfide nanorods. Therefore, the highly active sites at the interface are more easily exposed in the solution, making the catalytic activity of the entire material higher. The single-crystal nickel sulfide nanorods in the middle make it easier and faster for electrons to reach the active sites at the heterostructure interface of molybdenum oxide and nickel sulfide, which can significantly improve its conductivity and catalytic efficiency.

[0023] This invention discloses a method for in-situ preparation of a molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst using nickel foam (NF), where NF provides the nickel source required for the reaction. This method significantly reduces manufacturing costs while immobilizing the entire nanoarray catalyst on NF, resulting in a more stable structure and providing rapid charge transfer, thereby enhancing both catalytic activity and stability. Attached Figure Description

[0024] The specific details of this disclosure are described below with reference to the accompanying drawings, which will facilitate a more readily understanding of the above and other objects, features, and advantages of this disclosure. The drawings are merely for illustrating the principles of this disclosure. The dimensions and relative positions of the elements are not necessarily drawn to scale in the drawings.

[0025] Figure 1 The XRD pattern of the molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst of this invention is shown below.

[0026] Figure 2 This is a SEM image of the foamed Ni substrate of the present invention;

[0027] Figure 3 SEM images of the nickel sulfide structure and the molybdenum oxide-nickel sulfide heterostructure nanoarray of this invention;

[0028] Figure 4 This is a TEM image of the molybdenum oxide-nickel sulfide heterostructure nanoarray of the present invention;

[0029] Figure 5 XPS image of the molybdenum oxide-nickel sulfide heterostructure nanoarray of the present invention;

[0030] Figure 6 The graph shows the electrocatalytic hydrogen evolution performance test results of the molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst of this invention.

[0031] Figure 7 This is a schematic diagram illustrating the preparation process of the molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst and the nickel sulfide catalyst of the present invention. Detailed Implementation

[0032] Exemplary aspects of this disclosure will be described below with reference to the accompanying drawings. For clarity and brevity, not all features implementing this disclosure are described in the specification. However, it should be understood that many disclosure-specific decisions can be made in developing any such implementation of this disclosure to achieve the developer's specific goals, and these decisions may vary depending on the specific implementation of this disclosure.

[0033] It should also be noted that, in order to avoid obscuring the content of this disclosure with unnecessary details, only the content closely related to the scheme according to this disclosure is shown in the accompanying drawings, while other details that are not closely related to this disclosure are omitted.

[0034] It should be understood that this disclosure is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, features may be substituted or borrowed between different embodiments where feasible, and one or more features may be omitted in one embodiment.

[0035] To excite efficient water splitting of Ni3S2-based catalysts, we considered forming heterostructures composed of different material components through nanostructure engineering and composite material construction. In heterostructures, the strong coupling interaction between different phases at the interface is beneficial to optimizing the electronic structure and regulating the hydrogen adsorption energy, thereby improving the catalyst activity.

[0036] Furthermore, environmentally friendly and readily prepared transition metal oxides are good candidates for forming heterostructures, especially molybdenum-based oxides (MoO2). x Due to its extremely strong metal-oxygen bonds, Ni3S2 is considered a host material with strong interactions with polysulfides. Therefore, the inventors believe that Ni3S2 and MoO2... x The coupled heterostructure effectively optimizes the adsorption of ion molecules, thereby enhancing catalytic activity. Furthermore, MoO x Electron transfer and crystal distortion near the Ni3S2 interface may generate more active centers, thereby improving catalytic activity.

[0037] Furthermore, three-dimensional (3D) network structures can provide rapid charge transfer. Nickel foam (NF), due to its high electronic conductivity and high specific surface area, can serve as an inexpensive material for providing 3D network structures and can be used as a substrate and support for electrode materials. Therefore, in Ni3S2-MoO x In the process of preparing heterostructure catalysts, the inventors used NF as a substrate, which also served as a nickel source precursor in the Ni3S2 preparation process.

[0038] Example 1

[0039] Example 1 of this invention provides a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material, which can be used in the HER reaction and exhibits excellent catalytic activity. While increasing the active surface area, the grain-bound single-crystal nickel sulfide nanorods provide a "highway" for electrons, allowing electrons to reach the active sites at the heterostructure interface of molybdenum oxide and nickel sulfide more easily and quickly, accelerating the reaction kinetics of the material and significantly improving the catalytic efficiency of the HER reaction. Specifically, the catalyst morphology is a unique nanosphere-nanorosphere heterostructure array with a tree-like microstructure, where the "trunk"—nanorospheres—is Ni3S2, and the "branches"—nanospheres—are oxygen-deficient molybdenum oxide.

[0040] See Figure 1 The image shows the XRD pattern of the molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material of the present invention, wherein MoO x -Ni3S2 heterostructure nanoarrays were formed on a foamed Ni substrate (NF). Figure 1 In the figure, MoO is shown respectively. x XRD patterns of Ni3S2 / NF and Ni3S2 / NF materials, MoOx Ni3S2 / NF and Ni3S2 / NF exhibit three strong diffraction peaks at 44.5°, 51.8°, and 76.4°, belonging to the NF substrate (JCPDS No. 70-1849). The diffraction peaks at 21.8°, 31.1°, 37.8°, 49.7°, and 55.2° correspond to the (101), (110), (003), (113), and (122) crystal planes of Ni3S2 (JCPDS No. 76-1870). The peaks at 36.5°, 53.8°, and 65.7° are associated with MoO. x -Ni3S2 / NF is unique, corresponding to the (100), (102) and (110) planes of MoO2 (JCPDS No. 50-0739), respectively, indicating that Mo oxide is formed in the catalyst.

[0041] See Figure 2 The image shows a SEM image of a foamed Ni substrate. As can be seen from the image, the NF exhibits a three-dimensional porous structure and a smooth surface.

[0042] See Figure 3 These are scanning electron microscope (SEM) images of the nickel sulfide structure and the molybdenum oxide-nickel sulfide heterostructure nanoarray of this invention. Figure 3 a and Figure 3 In step b, unlike NF, the surface of the reacted Ni3S2 / NF becomes uneven, forming a serrated protrusion structure. In contrast, as... Figure 3 As shown in Figure cd, the incorporation of Mo significantly induces morphological changes in Ni3S2. A unique array of nanorods covered by nanospheres grows uniformly on the NF surface. The nanospheres are MoO2. x The nanorods are made of Ni3S2, with nanosphere radii of 30-100 nm, nanorod diameters of approximately 100-500 nm, and lengths of approximately 2.2-7.4 μm. The results show that the introduction of the Mo source significantly affects the morphology and structure. This one-dimensional nickel sulfide nanorod-molybdenum oxide nanosphere heterostructure array nanocatalyst increases the active area, while the interface possesses more highly active sites due to electron transfer and lattice distortion. The nanospheres grow on the surface of the nanorods but do not completely cover the nickel sulfide nanorods; therefore, the highly active sites at the interface are more easily exposed in the solution, resulting in higher catalytic activity of the entire material. The single-crystal nickel sulfide nanorods facilitate faster electron access to the active sites at the heterostructure interface between molybdenum oxide and nickel sulfide, significantly improving conductivity and catalytic efficiency. Furthermore, the nickel foam (NF) provides more stable support for the entire nanoarray catalyst.

[0043] See Figure 4 This is a TEM image of a molybdenum oxide-nickel sulfide heterostructure nanoarray. Figure 4 The nanosphere-nanorobot morphology was confirmed in a. Figure 4 Image bc shows high-resolution TEM (HRTEM) images of the nanospheres and nanorods, which can pinpoint the (101) plane of Ni3S2 and the (100) and (102) planes of MoO2, where the (101) plane of Ni3S2 is parallel to the (102) plane of MoO2. In addition to MoO2 crystals, the nanospheres also contain a large amount of MoO2. x Amorphous. Figure 4 In image d, the scanning TEM (STEM) image and the corresponding energy-dispersive X-ray (EDX) elemental spectrum image show that Ni and S elements are concentrated on the nanorods, while Mo and O elements are uniformly distributed on the nanospheres.

[0044] See Figure 5 The image shows the XPS plot of a molybdenum oxide-nickel sulfide heterostructure nanoarray. Figure 5 Figure a shows the S 2p XPS spectrum. The peaks at 162.7 and 163.9 eV in the Ni3S2 / NF sample are attributed to S in Ni3S2. 2- price. MoO x The peaks of Ni3S2 / NF (162.4 and 163.6 eV) show a negative shift compared to the peaks of Ni3S2 / NF, indicating that the introduction of Mo alters the electronic structure of Ni3S2. Figure 5 In b, MoO x In the high-resolution Ni 2p spectrum of Ni3S2 / NF, the main peaks at 855.9 and 873.1 eV can be attributed to Ni2p. 3 / 2 and Ni 2p 1 / 2 The two peaks at 878.7 and 861.5 eV are satellite peaks. Ni 2p of Ni3S2 3 / 2 and Ni 2p 1 / 2 The peaks are located at 855.6 eV and 872.9 eV, showing a significant positive shift of 0.3 eV compared to the previous value. This indicates that there may be strong electronic interactions between the heterojunctions, with some electrons moving from Ni3S2 to MoO. x Transfer. In Figure 5 In section c, regarding the O1s spectrum, the peak at 530.5 eV is attributed to lattice oxygen atoms, the peak at 533.0 eV is related to the HO bonds formed by surface-adsorbed water molecules, and the peak at 531.5 eV is attributed to oxygen atoms near oxygen vacancies, proving the presence of oxygen vacancies in the catalyst. Finally, in MoO... x In Ni3S2 / NF, the peaks of Mo were found to contain multiple valence levels. For example... Figure 5 As shown in Figure d, the Mo 3d spectrum contains three sets of doublets. The two strong peaks with binding energies of 230.3 eV and 233.5 eV correspond to Mo. 4+ Mo 3d 5 / 2 and Mo 3d 3 / 2The peaks at 231.5 eV and 234.6 eV correspond to Mo. 5+ Mo 3d 5 / 2 and Mo3d 3 / 2 The peaks at 232.6 eV and 234.6 eV correspond to Mo. 6+ Mo 3d 3 / 2 and Mo 3d 5 / 2， The presence of the Mo polyvalent state further promotes the generation of oxygen vacancies.

[0045] See Figure 6 The figure shows the electrocatalytic hydrogen evolution performance of the molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst. The electrocatalytic hydrogen evolution test was performed using a typical three-electrode system on the sample and two control groups. The sample and control groups were cut to 1.0 cm × 1.0 cm dimensions as the working electrode, a graphite electrode as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. The electrolyte was 1 M KOH solution. For comparison, the electrocatalytic activity of commercial Pt / C under the same conditions and mass loading was measured. Figure 6 As shown in figure a, Pt / C is undoubtedly the most active HER catalyst. (10 mA cm⁻¹) -2 The required Pt / C overpotential is 21 mV. NF (Ni foam) exhibits low HER activity, but the activity of Ni3S2 generated after sulfidation increases significantly at 10 mA cm⁻¹. -2 At that time, the overpotential decreased from 260mV to 170mV. After introducing a Mo source, MoO x The HER activity of -Ni3S2 / NF was further improved, and the overpotential decreased to 74 mV. For example... Figure 6 As shown in b. MoO x The Tafel slope of the Ni3S2 / NF composite is 85 mV dec. -1 The dec of Ni3S2 / NF nanostructure is lower than 132 mV. -1 MoO x The small Tafel slope of -Ni3S2 / NF indicates that the hydrogen generation rate increases rapidly with the applied overpotential. Furthermore, MoO x The relatively small Tafel slope of -Ni3S2 / NF follows the Volmer-Heyrovsky mechanism. Further research is needed on MoO... x The catalytic kinetics of the Ni3S2 / NF catalyst in the alkaline HER process were investigated by electrochemical impedance spectroscopy in the frequency range of 0.01 Hz to 100 kHz. The test results are as follows: Figure 6 As shown in c. Figure 6 The equivalent circuit inserted in c is used to fit the recorded data, where R s It is the equivalent series resistance, CPE is the constant phase element of the double-layer capacitor, Rct It is the charge transfer resistance. It can be seen that, compared to Ni3S2 / Ni nanostructures (9.6Ω) and NF (39.3Ω), MoO... x The Ni3S2 / NF composite exhibits a low charge transfer resistance (3.7 Ω). These results indicate that MoO2... x The high conductivity of Ni3S2 / NF allows for rapid electron transport on heterostructured nanorods grown on an NF conductive substrate. MoO x The ECSA of -Ni3S2 / NF was calculated using CV measurements. For example... Figure 6 As shown in d, MoO x -Ni3S2 / NF Cdl(46.6mF cm) -2 (5.0 mF cm) higher than Ni3S2 / NF -2 To evaluate MoO x The stability of -Ni3S2 / NF was demonstrated by recording the It curve of the long-term reaction of HER in 1M KOH at 1.7V (vs. RHE). Figure 6 e). The results show that during the 24-hour constant voltage electrolysis test, the current density remained essentially at 10 mA cm⁻¹. -2 There was no attenuation. This further proves the effectiveness of the MoO2 of this invention. x -Ni3S2 / NF electrocatalyst is a highly stable HER electrocatalyst in alkaline media, exhibiting excellent electrocatalytic performance and high stability.

[0046] Example 2

[0047] Example 2 of this invention provides a method for preparing a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material, see [link to documentation]. Figure 7 This diagram illustrates the reaction principle of the molybdenum oxide-nickel sulfide heterostructure nanoarray catalyst and nickel sulfide in this invention. The upper part of the diagram shows the preparation of Ni3S2 / NF using a foamed Ni substrate and thiourea. The lower part of the diagram shows the preparation of Ni3S2 / NF using a foamed Ni substrate, thiourea, and (NH4)6Mo7O. 24 MoO is prepared by the reaction of 4H2O. x -Ni3S2 / NF heterostructure nanoarray catalyst.

[0048] The specific preparation steps are as follows:

[0049] Step 1, Preparation of nickel foam substrate. First, cut a piece of nickel foam substrate and sonicate it in 1-5 mol / L hydrochloric acid for 5-20 min to remove the surface oxide layer; then clean the treated nickel foam substrate with anhydrous ethanol and deionized water by sonication for 10-40 min in sequence, and then vacuum dry it at 40-70℃ for 3-8 h.

[0050] Step 2, Preparation of thiourea and (NH4)6Mo7O 24 A homogeneous solution of thiourea and (NH4)6Mo7O. Specifically, weigh out thiourea and (NH4)6Mo7O in a molar ratio of 10-20:1. 24 • 4H2O, preferably, 1.5 mmol of thiourea and 0.1 mmol of (NH4)6Mo7O can be weighed. 24 • 4H₂O was dissolved in 25 ml of deionized water and magnetically stirred for 30 min to obtain a homogeneous solution. When thiourea and (NH₄)₆Mo₇O₇ were dissolved... 24 When the molar ratio of ·4H2O is 15:1, it can induce Ni3S2 to grow into rod-shaped structures and control the growth of MoO. x The nanospheres have a radius of 30-100 nm and do not completely cover the Ni3S2 nanorods, which allows the highly catalytically active two-phase interface to be exposed as much as possible in the reaction solution.

[0051] Step 3: React the nickel foam substrate prepared in Step 1 with the homogeneous solution prepared in Step 2 to obtain MoO. x -Ni3S2 / NF heterostructure nanoarray. Preferably, the stirred homogeneous solution is transferred to a 35ml high-pressure reactor lined with polytetrafluoroethylene, and a piece of the nickel foam substrate prepared in step 1 is placed in the solution; and the reactor is heated in a constant temperature drying oven at 180-220℃ for 8-15h.

[0052] Furthermore, step 4 can be included, where the sample obtained in step 3 is repeatedly washed. Specifically, after cooling, the sample prepared in step 3 is taken out and washed 3-6 times with deionized water and anhydrous ethanol, respectively. The washed sample is then vacuum-dried at 40-80℃ for 8-15 hours to obtain MoO. x -Ni3S2 / NF.

[0053] The preparation process of the comparative material Ni3S2 / NF is basically the same as the above steps, except that (NH4)6Mo7O is not added in step 2. 24 ·4H2O.

[0054] NF refers to the nickel foam substrate after step 2.

[0055] The following example further illustrates the preparation method of the present invention in detail.

[0056] 1) Cut a 1.0×3.0 cm piece of nickel foam substrate, sonicate it in 3 mol / L hydrochloric acid for 10 min to remove the surface oxide layer; clean the treated nickel foam substrate with anhydrous ethanol and deionized water by sonication for 30 min in sequence, and then vacuum dry it at 50℃ for 6 h.

[0057] 2) Weigh out 1.5 mmol of thiourea and 0.1 mmol of (NH4)6Mo7O 24 • Dissolve 4H2O in 25ml of deionized water and stir magnetically for 30min;

[0058] 3) Transfer the stirred homogeneous solution to a 35ml polytetrafluoroethylene-lined high-pressure reactor and place a pre-treated nickel foam substrate on it; put the reactor into an electric thermostatic drying oven and heat it at 200℃ for 12h.

[0059] 6) After cooling, remove the prepared sample and wash it 3-4 times with deionized water and anhydrous ethanol respectively. Dry the washed sample under vacuum at 60℃ for 12 hours to finally obtain MoO. x -Ni3S2 / NF.

[0060] The above specific embodiments are only for illustrating the technical concept and structural features of the present invention, and are intended to enable those skilled in the art to implement them. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the technical features of the present invention should fall within the scope of protection of the present invention.

[0061] The foregoing description of this disclosure in conjunction with specific implementation schemes is exemplary and not intended to limit the scope of protection of this disclosure. Those skilled in the art can make various modifications and variations to this disclosure based on its spirit and principles, and such modifications and variations are also within the scope of this disclosure.

Claims

1. A method for preparing a molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst, comprising the following steps: 1) Preparation of nickel foam (NF) substrate; 2) Preparation of thiourea and (NH4)6Mo7O 24 A homogeneous solution of 4H2O was prepared by weighing out thiourea and (NH4)6Mo7O in a molar ratio of 10-20:

1. 24 ·4H2O, dissolved in deionized water, and stirred to obtain a homogeneous solution; 3) React the nickel foam substrate prepared in step 1 with the homogeneous solution prepared in step 2 to obtain MoO. x -Ni3S2 / NF heterostructure nanoarray sample; In step 3, the homogeneous solution from step 2 is transferred to a high-pressure reactor lined with polytetrafluoroethylene, a piece of nickel foam substrate prepared in step 1 is placed in the solution, and the reactor is heated in a constant temperature drying oven at 180-220℃ for 8-15 hours. The prepared molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material is a nanorod array covered with nanospheres, grown on the surface of a nickel foam substrate, wherein the nanospheres are MoO x The nanorods are made of Ni3S2, the nanospheres have a radius of 30-100 nm, the nanorods have a diameter of 100-500 nm, and a length of 2.2-7.4 μm. The nanospheres grow on the surface of the nanorods but do not completely cover the nickel sulfide nanorods.

2. The preparation method according to claim 1, characterized in that: It also includes step 4: 4) Wash the sample obtained in step 3 repeatedly and then dry it.

3. The preparation method according to claim 1, characterized in that: In step 1, the nickel foam substrate is ultrasonically treated in 1-5 mol / L hydrochloric acid for 5-20 min to remove the surface oxide layer; the treated nickel foam substrate is ultrasonically cleaned with anhydrous ethanol and deionized water for 10-40 min in sequence, and then vacuum dried at 40-70℃ for 3-8 h.

4. The preparation method according to claim 1, characterized in that: In step 2, 1.5 mmol of thiourea and 0.1 mmol of (NH4)6Mo7O were weighed out. 24 Dissolve 4H2O in 25 ml of deionized water and stir magnetically for 30 min to obtain a homogeneous solution.

5. The preparation method according to claim 2, characterized in that: In step 4, the sample prepared in step 3 is washed 3-6 times with deionized water and anhydrous ethanol, respectively. The washed sample is then vacuum dried at 40-80℃ for 8-15 hours to obtain MoO. x -Ni3S2 / NF.

6. The molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material prepared by any one of the preparation methods in claims 1-5.

7. The molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material according to claim 6, characterized in that: The catalyst material is a nanorod array covered with nanospheres, grown on the surface of a nickel foam substrate, wherein the nanospheres are MoO2. x The nanorods are made of Ni3S2, the nanospheres have a radius of 30-100 nm, the nanorods have a diameter of 100-500 nm, and the length is 2.2-7.4 μm.

8. An application of the molybdenum oxide-nickel sulfide heterostructure nanoarray electrocatalyst material as described in claim 6 or 7 as a catalyst for hydrogen production by water electrolysis.

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