One-dimensional structure molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial and preparation method and application thereof

Abstract

The application provides a one-dimensional structure molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial and a preparation method and application thereof, one-dimensional rod-like NiMoO4 nanomaterial is prepared first, is uniformly wrapped by polydopamine hydrochloride, one-dimensional core-shell structure PDA@NiMoO4 nanomaterial is obtained, then high-temperature calcination is carried out to obtain MoO2 / Ni / MoC composite nanomaterial; then selenization is carried out to obtain one-dimensional rod-like structure MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of MoSe2, Ni3Se4 and MoC composite nanosheets; the above three substances all have catalytic hydrogen evolution reaction performance, and are one-dimensional structure composed of nanosheets, can effectively reduce the accumulation of the sheet structure material, makes the hydrogen evolution reaction catalytic active site of the sheet structure material more fully exposed, improves the catalytic activity of the material; as a hydrogen evolution reaction electrocatalyst, excellent catalytic activity is shown in an acidic and alkaline environment.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically relating to a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial, its preparation method, and its application. It can be used as a catalyst for the electrolysis of water to produce hydrogen under both acidic and alkaline environments. Background Technology

[0002] Energy scarcity and environmental pollution have been two major challenges facing human society in the 21st century. Due to the continuous growth of the world's population and the expansion of industrialization, unsustainable fossil fuels will eventually be depleted, and their consumption will lead to severe environmental pollution. Therefore, finding renewable and clean energy sources and developing efficient energy conversion technologies are urgent priorities.

[0003] Hydrogen is considered the most ideal renewable and clean energy source due to its high energy density and the fact that its combustion product is water. Electrolysis of water to produce hydrogen is an important pathway for the industrial production of hydrogen energy, as this method of converting electrical energy into chemical energy has advantages such as low cost, environmental friendliness, high efficiency, and safety. In this process, an electrocatalyst is needed to reduce the overpotential during water electrolysis to minimize energy consumption.

[0004] Although precious metals such as platinum exhibit excellent catalytic performance in the electrolytic hydrogen evolution reaction of water, their high cost and scarcity limit their large-scale application. Therefore, exploring efficient and low-cost non-precious metal catalysts for the hydrogen evolution reaction is of great significance for the widespread application of water electrolysis for hydrogen production. Summary of the Invention

[0005] The purpose of this invention is to provide a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial and its preparation method. The prepared composite nanomaterial is a one-dimensional nanorod structure composed of MoSe2 / Ni3Se4 / MoC composite nanosheets. The one-dimensional structure composed of nanosheets can effectively reduce the stacking of sheet-like materials, allowing the hydrogen evolution reaction catalytic active sites of the sheet-like materials to be more fully exposed, thereby improving the catalytic activity of the material. Moreover, the raw materials and process equipment used in the preparation process are simple and low in cost, which is conducive to large-scale production.

[0006] Another objective of this invention is to provide an application of a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial as a catalytic material for catalyzing the hydrogen evolution reaction in water electrolysis. It exhibits high catalytic performance and good catalytic activity for hydrogen evolution reaction in both acidic and alkaline environments.

[0007] The specific technical solution of this invention is as follows:

[0008] A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial includes the following steps:

[0009] A. NiMoO4 nanorods were added to a solvent and stirred until homogeneous to obtain solution a; dopamine hydrochloride was dissolved in a solvent to obtain solution b; solution b was added dropwise to solution a while stirring and reacting to obtain one-dimensional core-shell structured PDA@NiMoO4 nanomaterials.

[0010] B. One-dimensional core-shell structured PDA@NiMoO4 nanomaterials were calcined at high temperature under an inert atmosphere to obtain one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterials.

[0011] C. Add the selenium source to the solvent, and add the resulting selenium source solution dropwise to N,N-dimethylformamide. After mixing, add the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial and heat the mixture to obtain a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial.

[0012] In step A, the solvent used for the NiMoO4 nanorods is a mixed solution of anhydrous ethanol and deionized water; the volume ratio of the anhydrous ethanol to the deionized water is 1:2 to 1:4.

[0013] In step A, the ratio of the mass of NiMoO4 nanorods to the volume of anhydrous ethanol in solution a is 2:1 to 3:1 g / L;

[0014] In step A, the NiMoO4 nanorods are one-dimensional rod-shaped nickel molybdate (NiMoO4) nanomaterials;

[0015] The method for preparing the NiMoO4 nanorods is as follows: a molybdenum source and a nickel source are mixed in a solvent and heated to react, thereby obtaining a one-dimensional rod-shaped nickel molybdate (NiMoO4) nanomaterial.

[0016] In the preparation method of NiMoO4 nanorods, the mass ratio of molybdenum source to nickel source is 1:0.8 to 1:1; the concentration of molybdenum source in solvent is 0.02 mol / L to 0.03 mol / L; the molybdenum source is selected from soluble molybdenum salts containing or without crystallization water, preferably sodium molybdate (Na2MoO4); the nickel source is selected from soluble nickel salts containing or without crystallization water, preferably nickel chloride, nickel nitrate, or nickel sulfate, more preferably nickel chloride hexahydrate (NiCl2·6H2O); the solvent is selected from deionized water; the heating reaction refers to the reaction at 100–140℃ for 6–10 hours; the heating reaction is carried out in a high-pressure reactor with a polytetrafluoroethylene liner and the reactor is sealed; after the heating reaction is completed, the product is centrifuged, the separated product is washed with water and ethanol and then vacuum dried to obtain one-dimensional rod-shaped nickel molybdate (NiMoO4) nanomaterials.

[0017] In step A, the ratio of the mass of dopamine hydrochloride to the amount of solvent used in solution b is 20:1 to 30:1 g / L;

[0018] Furthermore, the volume ratio of solution b to solution a is 1:10 to 1:15;

[0019] In step A, the solvent used to dissolve dopamine hydrochloride is deionized water;

[0020] The stirring reaction mentioned in step A refers to stirring at 20–30°C for 10–12 hours.

[0021] After the reaction in step A is completed, the mixed solution is centrifuged, the product is separated, washed with water and ethanol, and then vacuum dried to obtain a one-dimensional core-shell structured nanomaterial of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0022] In step B, the high-temperature calcination refers to reacting for 1 to 4 hours at a heating temperature of 600 to 900°C.

[0023] In step B, the inert atmosphere refers to an argon or nitrogen inert atmosphere; preferably an argon atmosphere.

[0024] In step B, the high-temperature calcination involves placing 0.02–0.12 g of one-dimensional core-shell structured PDA@NiMoO4 nanomaterials in a ceramic boat, placing the ceramic boat in a tube furnace for high-temperature calcination, and obtaining one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterials after the reaction is complete.

[0025] In step C, the volume ratio of the selenium source to the solvent is 1:2 mol / L to 1:4 mol / L;

[0026] In step C, the selenium source is selected from selenium powder, selenium dioxide, and sodium selenite, preferably selenium powder;

[0027] In step C, the solvent used for the selenium source is hydrazine hydrate with a mass fraction of 85%; the selenium source is added to the solvent and stirred until the selenium source dissolves to obtain a selenium hydrazine hydrate solution;

[0028] In step C, the volume ratio of the selenium source solution to N,N-dimethylformamide is 1:4 to 1:6.

[0029] In step C, the mass ratio of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial to the volume ratio of the selenium source solution is 1:0.2 g / L to 1:0.4 g / L.

[0030] In step C, the heating reaction is carried out at 200–240°C for 10–14 hours; the heating reaction is carried out in a polytetrafluoroethylene liner in a high-pressure reactor, and the heating reaction is carried out in a sealed reactor.

[0031] In step C, after the reaction is complete, the product is centrifuged, the separated product is washed with water and ethanol, vacuum dried, and then heated to react, thus obtaining a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0032] This invention first uniformly coats the synthesized one-dimensional rod-shaped NiMoO4 nanomaterials with polydopamine hydrochloride to obtain a one-dimensional core-shell structured PDA@NiMoO4 nanomaterial. The subsequent high-temperature calcination of the one-dimensional core-shell structured PDA@NiMoO4 nanomaterial is carried out in an oxygen-free atmosphere. This ensures that the organic compound polydopamine hydrochloride, acting as the shell, does not burn at high temperatures but only carbonizes and decomposes into carbon. Because carbon has reducing properties, this invention further utilizes the carbon formed by the high-temperature decomposition of polydopamine hydrochloride, acting as the shell of the one-dimensional core-shell structured PDA@NiMoO4 nanomaterial, in an oxygen-free atmosphere to reduce the NiMoO4 nanorods in the core of the material to MoO2 and elemental Ni. After the carbon completely reduces NiMoO4, it can further react with the reduced MoO2 at high temperatures to obtain MoC. Although the one-dimensional core-shell structured PDA@NiMoO4 nanomaterials underwent a series of decomposition, carbonization, reduction, and chemical reactions during oxygen-free high-temperature calcination, the original one-dimensional NiMoO4 nanostructure was preserved due to the uniform encapsulation and support of the poly(dopamine hydrochloride) shell, resulting in a one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial. Furthermore, using a mild liquid-phase reaction, the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial reacted with a selenium hydrazine hydrate solution. MoO2 reacted to form MoSe2, and Ni reacted to form Ni3Se4, yielding a MoSe2 / Ni3Se4 / MoC composite nanomaterial. This invention, by designing a suitable liquid-phase reaction system using DMF (N,N-dimethylformamide) as a solvent, effectively reduces the aggregation tendency of two-dimensional sheet-like nanomaterials. Furthermore, by controlling the reaction temperature and the concentration of the selenium hydrazine hydrate solution, the MoO2 / Ni / MoC composite nanomaterial reacts with the selenium hydrazine hydrate solution at an appropriate reaction rate. This process allows the original one-dimensional rod-like structure of the MoO2 / Ni / MoC composite nanomaterial to be retained during the reaction to generate molybdenum selenide and nickel selenide, ultimately yielding a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of uniformly dispersed MoSe2 / Ni3Se4 / MoC composite nanosheets. Comparative examples also show that using water as the reaction system, or changing the concentration of the selenium hydrazine hydrate solution in the reaction system, does not yield the one-dimensional rod-like structure product composed of nanosheets prepared in this invention.

[0033] This invention provides a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial, prepared using the above-described method. The one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial is a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of MoSe2, Ni3Se4, and MoC composite nanosheets. The prepared one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial has a diameter of 400–500 nm, a length of 5–15 μm, and the nanosheets constituting the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial have a thickness of 8–12 nm.

[0034] This invention provides an application of a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial as an electrocatalyst for the electrolysis of water to produce hydrogen. The one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial can be used to catalyze the electrolysis of water to produce hydrogen under both acidic and alkaline environments, and exhibits good catalytic activity for the electrolysis of water to produce hydrogen.

[0035] The Gibbs free energy of hydrogen adsorption at the edges of the two-dimensional layered structure of MoSe2 is close to zero, making it a promising electrocatalyst for the hydrogen evolution reaction (HER). However, the active sites for the HER in layered MoSe2 are only located at the edges of the layers, while the basal surfaces are catalytically inert. Furthermore, the layered structure makes MoSe2 layers prone to aggregation and overlap, preventing sufficient exposure of the layer edges and reducing the number of active sites. In addition, MoSe2 itself has low conductivity and is unstable in alkaline environments, making it unable to effectively catalyze the HER under alkaline conditions. These shortcomings significantly inhibit the practical application of MoSe2 as a catalyst for the HER. Nickel selenides, such as NiSe, Ni3Se2, and Ni... x Se (0.5≤x≤1) and other compounds exhibit good catalytic activity and stability in the hydrogen evolution reaction (HER), and demonstrate excellent performance under alkaline conditions. However, the low conductivity of nickel selenides limits their HER catalytic activity. Transition metal carbides possess d-band electronic state densities similar to Pt group noble metals, among which molybdenum carbide (MoC) is considered a promising catalyst due to its favorable electronic structure and high conductivity. However, the weak hydrogen bonds in MoC hinder hydrogen adsorption during the HER reaction. Furthermore, MoC suffers from insufficient active surface area, all of which limit its catalytic performance in the HER reaction.

[0036] To address the shortcomings of single-material catalysis in the hydrogen evolution reaction (HER), this invention creatively combines MoSe2, Ni3Se4, and MoC, all possessing HER catalytic activity, to prepare a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial. In this invention, a simple hydrothermal method is first used to synthesize uniformly sized one-dimensional rod-shaped NiMoO4 nanomaterials. Then, dopamine hydrochloride is uniformly polymerized on the surface of the synthesized NiMoO4 nanorods at room temperature and in a liquid phase environment to form polydopamine hydrochloride (PDA), thereby obtaining a one-dimensional core-shell structured PDA@NiMoO4 nanomaterial. Further, the one-dimensional core-shell structured PDA@NiMoO4 nanomaterial is calcined at high temperature under an inert atmosphere. In an oxygen-free atmosphere, polydopamine hydrochloride gradually decomposes into carbon at high temperature. The carbon formed by high-temperature decomposition further reacts with NiMoO4: first, the carbon binds the MoO4 in NiMoO4. 2- Reduced to MoO2, Ni 2+ Ions are reduced to elemental Ni; after complete reduction of NiMoO4, carbon further reacts with the reduced MoO2 at high temperature to generate MoC. Thus, the one-dimensional core-shell structured PDA@NiMoO4 nanomaterial, under an oxygen-free atmosphere, undergoes high-temperature carbonization of the encapsulated product to obtain a Ni / MoO2 / MoC composite material. Finally, through liquid-phase selenization, MoSe2 / Ni3Se4 / MoC nanorods are obtained. The reaction system of this invention can effectively control the selenization reaction of the one-dimensional Ni / MoO2 / MoC nanomaterial, successfully preparing a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of MoSe2 / Ni3Se4 / MoC composite nanosheets. If the synthesis scheme of this invention is changed, the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial cannot be obtained.

[0037] The composite material prepared in this invention consists of three substances: MoSe2, Ni3Se4, and MoC, all of which possess catalytic hydrogen evolution reaction (HEER) properties. These three substances are generated from initially synthesized NiMoO4 nanorods through a series of reactions designed in this invention, resulting in a tight bond between the three substances. This gives the synthesized MoSe2 / Ni3Se4 / MoC composite nanomaterial itself more catalytically active sites. Furthermore, the composite material prepared in this invention is a one-dimensional nanorod structure composed of MoSe2 / Ni3Se4 / MoC composite nanosheets. This one-dimensional structure effectively reduces the accumulation of layered materials, allowing for more complete exposure of the catalytically active sites for the HEER reaction, thus improving the catalytic activity of the material. Simultaneously, the one-dimensional structure of the nanosheets also facilitates sufficient contact between the material and the electrolyte, increasing the mass transfer rate of the HEER reaction. In addition, MoC has excellent electrical conductivity; combining MoC with MoSe2 and Ni3Se4 effectively improves the conductivity of the material, promoting rapid electron transport in the electrocatalytic process, enhancing the kinetics of the HEER reaction, and further enhancing the catalytic performance of the material for the HEER reaction. Therefore, the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial prepared in this invention exhibits good catalytic performance for hydrogen evolution reaction under both acidic and alkaline environments due to its more catalytically active sites, specific morphology that is beneficial to the mass transfer process of hydrogen evolution reaction, and conductivity that is beneficial to electron transfer.

[0038] Compared with existing technologies, this invention prepares MoSe2 / Ni3Se4 / MoC composite nanomaterials via a liquid-phase method. The materials required for the preparation process are readily available and inexpensive, the experimental equipment is simple, the reaction is controllable, and it is easy to repeat. The MoSe2 / Ni3Se4 / MoC composite nanomaterials prepared by this invention exhibit excellent performance and low cost as electrocatalysts for the hydrogen evolution reaction, and are applicable in both acidic and alkaline environments, demonstrating significant practical application value. Attached Figure Description

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings;

[0040] Figure 1 The X-ray powder diffraction pattern of NiMoO4 obtained in step 1) of Example 1 is shown below.

[0041] Figure 2 The image is a scanning electron microscope image of NiMoO4 obtained in step 1) of Example 1;

[0042] Figure 3 The image is a transmission electron microscope image of PDA@NiMoO4 obtained in step 2) of Example 1;

[0043] Figure 4The X-ray powder diffraction pattern of the MoO2 / Ni / MoC composite material obtained in step 3) of Example 1 is shown below.

[0044] Figure 5 The image shown is a scanning electron microscope image of the MoO2 / Ni / MoC composite material obtained in step 3) of Example 1.

[0045] Figure 6 The image shows a scanning electron microscope (SEM) image of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 1.

[0046] Figure 7 The X-ray powder diffraction pattern of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 1 is shown below.

[0047] Figure 8 The image shows a transmission electron microscope (TEM) image of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 2.

[0048] Figure 9 The image shows a scanning electron microscope (SEM) image of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 3.

[0049] Figure 10 The scanning electron microscope image of the MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 4 shows that the product is a one-dimensional rod-shaped nanostructure composed of nanosheets, and the diameter of the prepared one-dimensional rod-shaped nanostructure material is about 500 nm.

[0050] Figure 11 The image shows a scanning electron microscope (SEM) image of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 5.

[0051] Figure 12 The image shown is a scanning electron microscope image of the product obtained in step 4) of Example 6;

[0052] Figure 13 The image shown is a scanning electron microscope image of the product obtained in step 4) of Example 7;

[0053] Figure 14 The image shown is a scanning electron microscope image of the product obtained in step 4) of Example 8;

[0054] Figure 15 The image shows the X-ray powder diffraction pattern of the Ni3Se4 material obtained in Example 8.

[0055] Figure 16 The X-ray powder diffraction pattern of the MoSe2 material obtained in Example 9 is shown.

[0056] Figure 17 The image shows the polarization curves of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in Example 1 and the catalytic hydrogen evolution reaction of Ni3Se4 and MoSe2 in 0.5 mol / L H2SO4 solution.

[0057] Figure 18 The graph shows the polarization curves of the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in Example 1 and the catalytic hydrogen evolution reaction of Ni3Se4 and MoSe2 in 1 mol / L KOH solution. Detailed Implementation

[0058] Example 1

[0059] A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial includes the following steps:

[0060] 1) Weigh 0.169 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.166 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water. Stir until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0061] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed to obtain solution a; weigh 0.25 g of polydopamine hydrochloride and add to 10 ml of deionized water, stir until completely dissolved to obtain solution b; add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, stir at 20°C for 12 hours; then centrifuge the mixed solution to separate the product, wash with water and ethanol 3 times, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0062] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0063] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the resulting solution to a 50 mL reaction vessel lined with polytetrafluoroethylene. After sealing the reaction vessel, place it in a constant temperature blower and heat it at 220 °C for 12 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0064] Figure 1 The X-ray powder diffraction pattern of the product obtained in step 1) of Example 1 is shown. The main diffraction peaks and the X-ray powder diffraction standard card for NiMoO4 (JCPDS No. 13-0128) indicate that the product obtained in step 1) of Example 1 is NiMoO4.

[0065] Figure 2 The image shows a scanning electron microscope (SEM) image of the product NiMoO4 obtained in step 1) of Example 1. The product is a smooth one-dimensional rod-shaped nanomaterial with a diameter of about 300 nm and a length of about 5-10 micrometers.

[0066] Figure 3 The transmission electron microscope image of the product PDA@NiMoO4 obtained in step 2) of Example 1 shows that the product is a one-dimensional core-shell structured nanomaterial with a uniform structure and a shell thickness of about 100 nm to 200 nm.

[0067] Figure 4 The X-ray powder diffraction pattern of the product obtained in step 3) of Example 1 shows that the main diffraction peaks are consistent with those of MoO2 (JCPDS No. 32-0671), Ni (JCPDS No. 04-0850), and MoC (JCPDS No. 08-0384) on the X-ray powder diffraction standard card, indicating that the product obtained in step 3) of Example 1 is a MoO2 / Ni / MoC composite material.

[0068] Figure 5 The image shows a scanning electron microscope (SEM) image of the MoO2 / Ni / MoC composite material obtained in step 3) of Example 1. The product is a one-dimensional rod-shaped nanomaterial with a rough surface. The diameter of the one-dimensional rod is about 300 nm and the length is about 5-15 μm.

[0069] Figure 6 The image shown is a scanning electron microscope (SEM) image of the product obtained in step 4) of Example 1, revealing that the product is a one-dimensional rod-shaped nanostructure composed of nanosheets. The diameter of the prepared one-dimensional rod-shaped nanostructure material is approximately 400 nm, the length is 5–15 μm, and the thickness of the nanosheets constituting the one-dimensional rod-shaped nanostructure material is approximately 10 nm.

[0070] Figure 7 The X-ray powder diffraction pattern of the product obtained in step 4) of Example 1 is shown below. The main diffraction peaks are consistent with those of MoSe2 (JCPDS No. 29-0914), Ni3Se4 (JCPDS No. 18-0890), and MoC (JCPDS No. 08-0384) on the X-ray powder diffraction standard cards, respectively. The X-ray powder diffraction pattern indicates that the final product obtained in step 4) of Example 1 is a one-dimensional rod-shaped MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of sheet-like MoSe2 / Ni3Se4 / MoC composite nanomaterials.

[0071] Example 2

[0072] A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial includes the following steps:

[0073] 1) Weigh 0.152 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.149 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water. Stir until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 100 °C for 10 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0074] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0075] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0076] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the solution to a 50 mL reaction vessel with a polytetrafluoroethylene liner, seal the reaction vessel, and place it in a constant temperature blower oven. Heat the reaction vessel at 200 °C for 14 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0077] Figure 8 The image shows a transmission electron microscope (TEM) image of the MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 2. The product is a one-dimensional rod-shaped nanostructure composed of nanosheets, and the diameter of the prepared one-dimensional rod-shaped nanostructure material is about 400 nm.

[0078] Example 3

[0079] A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial includes the following steps:

[0080] 1) Weigh 0.146 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.132 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 140 °C for 6 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0081] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0082] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0083] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the solution to a 50 mL reaction vessel with a polytetrafluoroethylene liner, seal the reaction vessel, and place it in a constant temperature blower oven. Heat the reaction vessel at 220℃ for 10 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60℃ for 6 h to obtain the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0084] Figure 9 The image shows a scanning electron microscope image of the MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 3. The product is a one-dimensional rod-shaped nanostructure composed of nanosheets, and the diameter of the prepared one-dimensional rod-shaped nanostructure material is about 500 nm.

[0085] Example 4

[0086] A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial includes the following steps:

[0087] 1) Weigh 0.186 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.183 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0088] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0089] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0090] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the solution to a 50 mL reaction vessel lined with polytetrafluoroethylene, seal the reaction vessel and place it in a constant temperature blower oven, and heat it at 220℃ for 12 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60℃ for 6 h to obtain the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0091] Figure 10 The image shows a scanning electron microscope (SEM) image of the MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 4. The product is a one-dimensional rod-shaped nanostructure composed of nanosheets. The diameter of the prepared one-dimensional rod-shaped nanostructure is approximately 500 nm.

[0092] Example 5

[0093] A method for preparing a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial includes the following steps:

[0094] 1) Weigh 0.203 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.199 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0095] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0096] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0097] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 25 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the solution to a 50 mL reaction vessel lined with polytetrafluoroethylene, seal the reaction vessel and place it in a constant temperature blower oven, and heat it at 220℃ for 12 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60℃ for 6 h to obtain the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial.

[0098] Figure 11 The image shows a scanning electron microscope (SEM) image of the MoSe2 / Ni3Se4 / MoC composite nanomaterial obtained in step 4) of Example 5. The product is a one-dimensional rod-shaped nanostructure composed of nanosheets. The diameter of the prepared one-dimensional rod-shaped nanostructure is approximately 400 nm.

[0099] Example 6 (Failure Case)

[0100] A method for preparing MoSe2 / Ni3Se4 / MoC composite nanomaterials includes the following steps:

[0101] 1) Weigh 0.169 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.166 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0102] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0103] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0104] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of N,N-dimethylformamide and stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution and stir until the material is evenly dispersed in the mixed solution. Transfer the solution into a 50 mL reaction vessel lined with polytetrafluoroethylene, seal the reaction vessel, and place it in a constant temperature blower. 100℃ The reaction was heated at a constant temperature for 12 hours. After the reaction was completed, the reaction vessel was cooled to room temperature, the product was collected by centrifugation, washed three times with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 6 hours.

[0105] Figure 12The scanning electron microscope image of the product obtained in step 4) of Example 6 shows that the product consists of irregular particles of varying sizes, and is not a one-dimensional rod-shaped nanomaterial composed of nanosheets. The temperature of the final selenization reaction in Example 6 did not meet the requirements of this invention, resulting in the inability to obtain the product with the morphology of this application.

[0106] Example 7 (Failure Case)

[0107] A method for preparing MoSe2 / Ni3Se4 / MoC composite nanomaterials includes the following steps:

[0108] 1) Weigh 0.169 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.166 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0109] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0110] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0111] 4) Weigh Add 1 mmol of selenium powder to 1 mL Selenium powder was stirred in an 85% hydrazine hydrate (N₂H₄·H₂O) solution until completely dissolved, yielding a hydrazine hydrate solution of selenium powder. The hydrazine hydrate solution of selenium powder was then added dropwise to... 25mLIn N,N-dimethylformamide, stir until the two are thoroughly mixed. Add the following to the above mixed solution: 20mg The one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) was stirred until the material was uniformly dispersed in the mixed solution. The solution was transferred to a 50 mL reaction vessel lined with polytetrafluoroethylene, and the reaction vessel was sealed and placed in a constant temperature blower oven at 220 °C for 12 h. After the reaction was completed, the reaction vessel was cooled to room temperature, the product in the vessel was collected by centrifugation, washed three times with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60 °C for 6 h.

[0112] Figure 13 The image shown is a scanning electron microscope (SEM) image of the product obtained in step 4) of Example 7. It reveals that the product consists of a one-dimensional rod-shaped structure and irregular particles of varying sizes, rather than a single one-dimensional rod-shaped nanomaterial composed of nanosheets. In Example 7, simply changing the concentration of the selenium source solution resulted in a significant alteration in morphology.

[0113] Example 8 (Failure Case)

[0114] A method for preparing MoSe2 / Ni3Se4 / MoC composite nanomaterials includes the following steps:

[0115] 1) Weigh 0.169 g of sodium molybdate dihydrate (Na2MoO4·2H2O) and 0.166 g of nickel chloride hexahydrate (NiCl2·6H2O), and add them sequentially to 30 mL of deionized water, stirring until both are completely dissolved. Transfer the resulting solution into a 50 mL reaction vessel lined with polytetrafluoroethylene. Seal the reaction vessel and place it in a constant temperature oven at 120 °C for 8 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, and wash it three times with deionized water and anhydrous ethanol. Dry the product in a vacuum drying oven at 60 °C for 6 h to obtain one-dimensional rod-shaped NiMoO4 nanomaterials.

[0116] 2) Measure 40 ml of anhydrous ethanol and 90 ml of deionized water into a beaker, stir to mix evenly, then add 100 mg of NiMoO4 nanorods prepared in step 1), stir until evenly dispersed, to obtain solution a. Weigh 0.25 g of polydopamine hydrochloride and add it to 10 ml of deionized water, stir until completely dissolved, to obtain solution b. Add solution b dropwise to solution a while stirring, place the beaker containing the mixed solution in a constant temperature water bath, and stir at 20°C for 12 hours. Afterwards, centrifuge the mixed solution to separate the product, wash it three times with water and ethanol, and dry the product at 60°C for 6 hours in a vacuum drying oven to obtain one-dimensional core-shell structured nanomaterials of NiMoO4 encapsulated with polydopamine hydrochloride (PDA) (PDA@NiMoO4).

[0117] 3) Weigh 0.06g of PDA@NiMoO4 obtained in step 2) and place it in a ceramic boat. Put the ceramic boat into a tube furnace and heat it at 800℃ for 2 hours in an argon atmosphere. After the temperature drops to room temperature, the product obtained in the ceramic boat is a one-dimensional rod-shaped molybdenum dioxide / nickel / molybdenum carbide (MoO2 / Ni / MoC) composite nanomaterial.

[0118] 4) Weigh 2 mmol of selenium powder and add it to 5 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder. Add the hydrazine hydrate solution of selenium powder dropwise to 25 mL of the solution. Deionized water Stir until the two are evenly mixed. Add 20 mg of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial obtained in step 3) to the above mixed solution, and stir until the material is evenly dispersed in the mixed solution. Transfer the solution into a 50 mL reaction vessel lined with polytetrafluoroethylene, seal the reaction vessel and place it in a constant temperature blower oven, and heat at 220 °C for 12 h. After the reaction is completed, cool the reaction vessel to room temperature, collect the product in the vessel by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60 °C for 6 h.

[0119] Figure 14 The image shown is a scanning electron microscope (SEM) image of the product obtained in step 4) of Example 8. It reveals that the product is an irregular blocky structure, not a one-dimensional rod-shaped nanomaterial composed of nanosheets. In Example 8, simply changing the selenized solution to deionized water resulted in a significant change in morphology.

[0120] Example 9 (Comparative Sample Synthesis Case)

[0121] The preparation method of the comparative sample Ni3Se4 material includes the following steps:

[0122] 1) Weigh 1 mmol of selenium powder and add it to 3 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder.

[0123] 2) Weigh 1 mmol of NiCl2·6H2O and add it to 30 mL of N,N-dimethylformamide, stirring until completely dissolved. Add the hydrazine hydrate solution of selenium powder obtained in step 1) dropwise to this solution, stirring until homogeneous. Transfer the solution to a 50 mL reaction vessel lined with polytetrafluoroethylene, seal the vessel, and place it in a constant temperature oven. Heat the reaction vessel at 200 °C for 12 h. After the reaction is complete, cool the reaction vessel to room temperature, collect the product by centrifugation, wash it three times with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60 °C for 6 h to obtain Ni3Se4 material.

[0124] Figure 15The X-ray powder diffraction pattern of the product obtained in Example 8 shows that its main diffraction peaks are consistent with Ni3Se4 (JCPDS No. 18-0890) on the X-ray powder diffraction standard card, indicating that the obtained product is Ni3Se4.

[0125] Example 10 (Comparative Sample Synthesis Case)

[0126] The preparation method of the comparative sample MoSe2 material includes the following steps:

[0127] 1) Weigh 1 mmol of selenium powder and add it to 3 mL of 85% hydrazine hydrate (N2H4·H2O) solution. Stir until the selenium powder is completely dissolved to obtain a hydrazine hydrate solution of selenium powder.

[0128] 2) The hydrazine hydrate solution of selenium powder obtained in step 1) was added dropwise to 30 mL of N,N-dimethylformamide, and stirred until the two were evenly mixed. 30 mg of MoO3 was added to the above mixture, and stirred until it was evenly dispersed in the mixture. The solution was transferred to a 50 mL reaction vessel lined with polytetrafluoroethylene. The reaction vessel was sealed and placed in a constant temperature oven, and heated at 200 °C for 12 h. After the reaction was complete, the reaction vessel was cooled to room temperature, and the product was collected by centrifugation. The product was washed three times with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60 °C for 6 h to obtain MoSe2 nanomaterials.

[0129] Figure 16 The X-ray powder diffraction pattern of the product obtained in Example 9 shows that its main diffraction peaks are consistent with MoSe2 (JCPDS No. 29-0914) on the X-ray powder diffraction standard card, indicating that the obtained product is MoSe2.

[0130] Example 11

[0131] The application of a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial in the field of catalytic water electrolysis for hydrogen production, and the specific application method is as follows:

[0132] The one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterials obtained in Example 1 were used as catalysts to test their performance in catalytic water electrolysis for hydrogen evolution under acidic and alkaline environments. The performance was tested at room temperature using 0.5M H₂SO₄ solution and 1M KOH solution as the electrolyte solutions in the acidic and alkaline environments, respectively, employing a standard three-electrode system. A graphite rod was used as the counter electrode, and a silver / silver chloride (Ag / AgCl) electrode as the reference electrode. The one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterials obtained in Example 1, the Ni3Se4 material obtained in Example 6, and the MoSe2 material obtained in Example 7 were fixed onto the surface of a glassy carbon electrode using Nafion reagent, serving as the working electrodes. Linear sweep voltammetry was used to test the catalytic hydrogen evolution reaction performance.

[0133] Figure 17 This is a polarization curve of the hydrogen evolution reaction catalyzed by one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterials, Ni3Se4, and MoSe2 in 0.5 mol / L H2SO4 solution. The polarization curves are shown when the current density is 10 mA / cm². 2 At that time, the overpotential of MoSe2 was 208 mV, the overpotential of Ni3Se4 was 261 mV, while the overpotential of MoSe2 / Ni3Se4 / MoC was only 91 mV. The test results show that, compared with Ni3Se4 and MoSe2, the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial has better catalytic performance for hydrogen evolution reaction in acidic environment.

[0134] Figure 18 This is a polarization curve of the hydrogen evolution reaction catalyzed by one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterials, Ni3Se4 materials, and MoSe2 materials in 1 mol / L KOH solution. The polarization curves are shown when the current density is 10 mA / cm². 2 At the specified time, the overpotential of MoSe2 was 203 mV, that of Ni3Se4 was 261 mV, while the overpotential of MoSe2 / Ni3Se4 / MoC was only 105 mV. The test results show that, compared with Ni3Se4 and MoSe2, the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial exhibits better catalytic performance for hydrogen evolution reaction in an alkaline environment.

Claims

1. A method for preparing a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial, characterized in that, The preparation method includes the following steps: A. NiMoO4 nanorods were added to a solvent and stirred until homogeneous to obtain solution a; dopamine hydrochloride was dissolved in a solvent to obtain solution b; solution b was added dropwise to solution a while stirring and reacting to obtain one-dimensional core-shell structured PDA@NiMoO4 nanomaterials. B. One-dimensional core-shell structured PDA@NiMoO4 nanomaterials were calcined at high temperature under an inert atmosphere to obtain one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterials. C. Add the selenium source to hydrazine hydrate, and add the resulting selenium source solution dropwise to N,N-dimethylformamide. After mixing, add the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial and heat the reaction to obtain the one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial. In step C, the mass ratio of the one-dimensional rod-shaped MoO2 / Ni / MoC composite nanomaterial to the volume ratio of the selenium source solution is 1:0.2 g / L to 1:0.4 g / L; the molar ratio of the selenium source to the volume ratio of hydrazine hydrate is 1:2 mol / L to 1:4 mol / L; the heating reaction is carried out at 200–240 °C for 10–14 hours.

2. The preparation method according to claim 1, characterized in that, In step A, the solvent used for the NiMoO4 nanorods is a mixed solution of anhydrous ethanol and deionized water; the volume ratio of the anhydrous ethanol to the deionized water is 1:2 to 1:4; the mass ratio of the NiMoO4 nanorods to the volume of the anhydrous ethanol in solution a is 2:1 to 3:1 g / L.

3. The preparation method according to claim 1 or 2, characterized in that, In step A, the NiMoO4 nanorods are prepared by mixing a molybdenum source and a nickel source in a solvent and heating them to obtain a one-dimensional rod-shaped nickel molybdate nanomaterial.

4. The preparation method according to claim 1 or 2, characterized in that, In step B, the calcination refers to reacting for 1 to 4 hours at a heating temperature of 600 to 900°C.

5. The preparation method according to claim 1 or 2, characterized in that, In step C, the volume ratio of the selenium source solution to N,N-dimethylformamide is 1:4 to 1:

6.

6. A one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial prepared by the preparation method according to any one of claims 1-5, characterized in that, The one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial is a one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial composed of MoSe2, Ni3Se4 and MoC composite nanosheets; its diameter is 400-500 nm, its length is 5-15 μm, and the thickness of the nanosheets constituting the one-dimensional MoSe2 / Ni3Se4 / MoC composite nanomaterial is 8-12 nm.

7. The application of a one-dimensional molybdenum selenide / nickel selenide / molybdenum carbide composite nanomaterial prepared by the preparation method according to any one of claims 1-5 in the hydrogen evolution reaction of water electrolysis.

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