A MoS2 / Ni3S4 / CFP electrocatalyst with ampere-level current density stability, its preparation method, and its application.

Abstract

The application discloses an amperometric current density stable MoS2 / Ni3S4 / CFP electrocatalyst and a preparation method and application thereof, and belongs to the technical field of electrocatalytic hydrogen evolution. The application constructs a heterojunction interface between MoS2 and Ni3S4 through a hydrothermal reaction, and MoS2 and Ni3S4 generate a heterojunction on a carbon paper substrate to obtain the amperometric current density stable MoS2 / Ni3S4 / CFP electrocatalyst. The preparation of the composite material comprises the following steps: (1) dissolving nickel salt, urea and ammonium fluoride in water, stirring, and then placing the obtained mixed solution A and carbon paper in a hydrothermal reaction kettle for one-time hydrothermal reaction to obtain a nickel hydroxide precursor; (2) dissolving molybdenum salt and thiourea in water, stirring, and then placing the obtained mixed solution B and the nickel hydroxide precursor in the hydrothermal reaction kettle for two-time hydrothermal reaction to obtain the catalyst. The catalyst improves the electron transfer rate, increases the number of active sites, and exhibits excellent hydrogen evolution reaction activity and stability in the water electrolysis process.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic hydrogen evolution technology, specifically relating to a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density, its preparation method, and its application. Background Technology

[0002] Energy and the environment are major issues for the sustainable development of human society. The trend is towards shifting from fossil fuels to sustainable, pollution-free non-fossil energy sources. Hydrogen, as a clean, efficient, and sustainable energy carrier, is currently recognized as an ideal alternative to fossil fuels. Electrochemical catalytic water splitting is considered a highly efficient and green method for hydrogen production. Numerous electrocatalysts for hydrogen evolution reaction (HER) have been developed, with precious metals such as Pt and Pd exhibiting excellent catalytic activity. However, their high price and scarce reserves hinder large-scale industrial application, thus impacting industrial development.

[0003] Among numerous candidate materials for electrocatalytic hydrogen evolution, transition metal sulfides (TMSs), such as MoS2 and Ni3S4, have potential applications in electrocatalysis and energy storage and conversion due to their unique physicochemical properties. MoS2 is a layered compound formed by van der Waals forces, with the top and bottom layers consisting of sulfur atoms and the middle layer of molybdenum atoms. Theoretical calculations and experiments have shown that the exposed sulfur atoms at the edges possess high chemisorption energies for hydrogen, comparable to those of phosphorus (Pt). Therefore, an increasing number of researchers are dedicated to developing MoS2-based electrocatalysts, such as synthesizing MoS2 nanomaterials with different morphologies, constructing defect-state MoS2, and doping with other atoms. For example, patent publication number CN 115772681 A discloses a nickel-selenium co-doped molybdenum disulfide catalyst supported on carbon paper, its preparation method and application. In this method, nickel-selenium co-doped MoS2 is grown vertically in situ on carbon paper, and the edge active sites of the material are fully exposed. The co-doping of nickel and selenium is conducive to the generation of defects. The larger selenium atoms can expand the interlayer spacing of molybdenum disulfide and reduce stacking. These factors are all conducive to nickel-selenium co-doped molybdenum disulfide exhibiting better electrocatalytic hydrogen evolution performance. Patent publication number CN 114318392 A discloses a MoS2-NiS2 / NF hydrogen evolution material, its preparation method, and its application. In this method, sodium molybdate dihydrate, nickel nitrate hexahydrate, and hexamethylenetetramine are mixed, and MoO2-Ni(OH)2 is loaded onto nickel foam via a hydrothermal reaction to obtain MoO2-Ni(OH)2 / NF. This material is then calcined with sulfur powder under anaerobic conditions to form MoS2-NiS2 on the nickel foam, resulting in the MoS2-NiS2 / NF hydrogen evolution material. In this composite material, strong interactions occur between the MoS2-NiS2 nanoparticles and the porous nickel foam, giving it excellent performance in the hydrogen evolution reaction. However, the limited number of active sites and poor stability of the composite material still restrict the development of industrial water electrolysis.

[0004] Constructing heterojunctions is an effective strategy for improving material stability and promoting electron transfer and catalytic kinetics. Ni3S4, a nickel-based compound with mixed valence states, can provide abundant electrons and effectively promote charge transfer. When Ni3S4 is combined with MoS2, the strongly electronegative S atoms can capture more electrons from Ni, leading to the formation of higher valence states of Ni, which act as hydroxyl acceptors in the heterojunction, greatly promoting the decomposition of water molecules. However, due to the difficulty in synthesizing Ni3S4, Ni3S4 and Ni3S4-based catalysts are rarely reported. Therefore, it is necessary to develop a new solution that fully utilizes the unique physicochemical properties of MoS2 and Ni3S4 while constructing a heterojunction between MoS2 and Ni3S4 to regulate the charge distribution and local structure on their surfaces, in order to design and develop novel MoS2-based ampere-level electrocatalytic hydrogen evolution materials. Summary of the Invention

[0005] To address the above problems, this invention provides a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density, its preparation method, and its application. A heterogeneous interface is constructed between MoS2 and Ni3S4 through a hydrothermal reaction, and a heterojunction is formed between MoS2 and Ni3S4 on a carbon paper (CFP) substrate, resulting in a MoS2 / Ni3S4 / CFP electrocatalyst with a three-dimensional petal-like structure. This catalyst exhibits excellent reactivity and stability in the hydrogen evolution reaction.

[0006] This invention is achieved through the following technical solution:

[0007] An ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst is obtained by constructing a heterogeneous interface between MoS2 and Ni3S4 through a hydrothermal reaction, and forming a heterojunction between MoS2 and Ni3S4 on a carbon paper substrate.

[0008] Furthermore, the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst has a three-dimensional petal-like structure.

[0009] A method for preparing the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst as described above includes the following steps:

[0010] (1) Preparation of precursor: Nickel salt, urea and ammonium fluoride were dissolved in water and stirred continuously until completely dissolved to obtain mixed solution A. Mixed solution A and carbon paper were placed in a hydrothermal reactor, sealed and transferred to an oven for a hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled naturally to room temperature. After washing and drying, nickel hydroxide precursor was obtained.

[0011] (2) Preparation of catalyst: Molybdenum salt and thiourea were dissolved in water and stirred until completely dissolved to obtain mixed solution B. Mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed and transferred to an oven for a second hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled to room temperature naturally. After washing and drying, a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere current density was obtained.

[0012] Further, in step (1), the nickel salt is NiCl2·6H2O, Ni(NO3)2·6H2O or NiSO4·6H2O.

[0013] Further, in step (1), the molar ratio of nickel salt, urea and ammonium fluoride is 4:7~9:11.5~13; the concentrations of nickel salt, urea and ammonium fluoride in the mixed solution A are 0.2mol / L, 0.35~0.45mol / L and 0.575~0.65mol / L, respectively.

[0014] Further, in step (1), the hydrothermal reaction is carried out at a temperature of 100-120°C for 10-12 hours.

[0015] Further, in step (2), the molybdenum salt is (NH4)6Mo7O 24 ·4H2O, MoCl5 or Na2MoO4·2H2O.

[0016] Further, in step (2), the molar ratio of molybdenum salt to thiourea is 1:7 to 9; the concentrations of molybdenum salt and thiourea in the mixed solution B are 0.05 mol / L and 0.35 to 0.45 mol / L, respectively.

[0017] Furthermore, in step (2), the secondary hydrothermal reaction is carried out at a temperature of 180–200°C for 22–24 hours.

[0018] Application of a MoS2 / Ni3S4 / CFP electrocatalyst with ampere-level current density stability as described above in the hydrogen evolution reaction.

[0019] In the preparation of the MoS2 / Ni3S4 / CFP electrocatalyst of this invention, carbon paper (CFP) is used as a substrate. During the reaction, both the nickel hydroxide precursor and the MoS2 / Ni3S4 / CFP electrocatalyst are generated on the carbon paper. Using carbon paper as a substrate requires consideration of its hydrophilicity and hydrophobicity. Acid treatment can alter the surface properties of the carbon paper, changing it from hydrophobic to hydrophilic, thus better adapting it to the conditions required for catalyst preparation. Therefore, the carbon paper used in this invention needs to undergo the following treatment before use:

[0020] Cut the carbon paper into 2.4cm × 2cm pieces. Place the cut carbon paper in a round-bottom flask, add concentrated nitric acid to immerse it, and then heat and stir it in an oil bath at 90–100℃ and 100–200 rpm. Next, immerse it in acetone, sonicate it for 15 minutes, and then rinse it with deionized water. Finally, immerse it in ethanol, sonicate it for 15 minutes, rinse it with deionized water, and then soak it in deionized water for later use.

[0021] The preparation principle of the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst of the present invention:

[0022] (1) In a hydrothermal reaction, nickel salt dissolves in water, providing divalent nickel ions and hydroxide ions. These ions react under high temperature and pressure to generate nickel hydroxide. Urea plays a key role in altering the polarity of the solution, further influencing the mass transfer process and consequently affecting the morphology of the nickel hydroxide crystals. Ammonium fluoride primarily provides fluoride ions that selectively adsorb onto a specific crystal facet of nickel hydroxide, thereby altering the crystallization kinetics of each facet and ultimately leading to differences in crystal morphology. Carbon paper (CFP) serves as the reaction substrate. Therefore, by controlling the ratio of nickel salt, urea, and ammonium fluoride, ultrathin nickel hydroxide nanosheets are generated on a carbon paper substrate, serving as a precursor for the next hydrothermal reaction.

[0023] (2) In the secondary hydrothermal reaction, nickel hydroxide precursor, molybdenum salt and thiourea are mixed. Molybdenum salt provides molybdate and thiourea provides sulfur ions. The two react to obtain MoS2. At the same time, sulfur ions react with nickel hydroxide precursor to obtain Ni3S4. MoS2 and Ni3S4 are combined through hydrothermal reaction to form MoS2 / Ni3S4 nanoheterojunction on carbon paper (CFP) substrate, forming a composite material with a specific interface structure, namely MoS2 / Ni3S4 / CFP electrocatalyst. In this heterostructure, the different energy band arrangements of different phases lead to charge transfer at the interface, which is beneficial to surface electron regulation and improves the electron transfer rate, so that the composite material has good reactivity and stability in the hydrogen evolution reaction.

[0024] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0025] 1. This invention constructs a heterostructure between MoS2 and Ni3S4 via a hydrothermal reaction, forming a heterojunction between MoS2 and Ni3S4 on a carbon paper substrate to obtain a MoS2 / Ni3S4 / CFP electrocatalyst. This method differs from the primary hydrothermal synthesis method. This invention first uses carbon paper as a substrate and generates a nickel hydroxide precursor on the carbon paper substrate via a primary hydrothermal reaction. During this process, urea and ammonium fluoride are added to the reaction system as structure directing agents. By influencing the crystallization kinetics of each crystal facet, an ultrathin sheet-like nickel hydroxide precursor is obtained. This nickel hydroxide precursor is then used as a growth substrate for a secondary hydrothermal reaction, and the reaction conditions are modified to achieve in-situ sulfidation, resulting in a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density.

[0026] 2. In the first hydrothermal reaction, the concentrations of urea and ammonium fluoride are controlled at 0.35–0.45 mol / L and 0.575–0.65 mol / L, respectively, resulting in the formation of a nickel hydroxide precursor with a two-dimensional sheet structure on the surface of the carbon paper substrate, with increased sheet thickness. After the second hydrothermal reaction, the composite material exhibits numerous three-dimensional petal-like structures perpendicular to the substrate. Simultaneously, in the second hydrothermal reaction, the concentration of thiourea is controlled at 0.35–0.45 mol / L to avoid the formation of NiS and NiS2, resulting in a MoS2 / Ni3S4 heterostructure with two coexisting phases in the composite material. Furthermore, the reaction time for the second hydrothermal reaction is controlled at 22–24 h, suitable for the growth of the MoS2 / Ni3S4 heterojunction. The resulting three-dimensional nano-petal-like structure has a regular morphology and a clear microlayered structure.

[0027] 3. In the MoS2 / Ni3S4 heterostructure of this invention, Ni3S4 is a sulfide with mixed valence states, namely, divalent and trivalent nickel ions. The XPS image shows that Ni in MoS2 / Ni3S4... 3+ The content is significantly higher than that of Ni. 2+ Nickel ions, on the other hand, are more conducive to the adsorption of hydroxide ions. Compared with NiS2 and NiS, they have a lower adsorption free energy for hydroxide ions, which in turn promotes the dissociation of water molecules.

[0028] 4. The MoS2 / Ni3S4 / CFP electrocatalyst prepared in this invention possesses a three-dimensional petal-like structure, resulting in a high specific surface area and high hydrogen evolution reaction activity. This three-dimensional heterojunction electrode material enhances the electron transfer rate and increases the number of active sites, exhibiting superior hydrogen evolution reaction activity and stability compared to ordinary two-dimensional materials during water electrolysis. When this catalyst is applied to the hydrogen evolution reaction, it achieves a hydrogen evolution reaction activity of 1 A / cm². 2 At current density, its overpotential is as low as 268mV, and it can operate stably for 100 hours, as well as maintain good stability under sudden voltage changes.

[0029] 5. The preparation method of the present invention is simple, easy to operate, mild, and low in cost. The catalyst obtained has good reactivity and stability in the hydrogen evolution reaction and can work stably for a long time under ampere-level high current density. It has great application value for efficient and green hydrogen production and is suitable for large-scale industrial use. Attached Figure Description

[0030] Figure 1 This is a low-magnification SEM image of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0031] Figure 2 This is a high-magnification SEM image of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0032] Figure 3 This is a TEM image of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0033] Figure 4 The image shows an HRTEM image of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0034] Figure 5 The image shows the XRD pattern of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0035] Figure 6 XPS spectrum of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0036] Figure 7 ECSA image of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0037] Figure 8 ECSA image of the Ni3S4 / CFP composite nanoelectrode prepared for Comparative Example 1.

[0038] Figure 9 ECSA image of the MoS2 / CFP composite nanoelectrode prepared for Comparative Example 2.

[0039] Figure 10 The graph shows the calculated Cdl values ​​of the MoS2 / Ni3S4 / CFP electrocatalyst, Ni3S4 / CFP composite nanoelectrode, and MoS2 / CFP composite nanoelectrode prepared in Example 1 and Comparative Examples 1-2, respectively.

[0040] Figure 11 LSV images of the MoS2 / Ni3S4 / CFP electrocatalyst, Ni3S4 / CFP composite nanoelectrode, MoS2 / CFP composite nanoelectrode, Pt / CFP electrode, and CFP electrode prepared in Example 1 and Comparative Examples 1-4, respectively.

[0041] Figure 12 Tafel images of the MoS2 / Ni3S4 / CFP electrocatalyst, Ni3S4 / CFP composite nanoelectrode, MoS2 / CFP composite nanoelectrode, Pt / CFP electrode, and CFP electrode prepared in Example 1 and Comparative Examples 1-4, respectively.

[0042] Figure 13 The image shows the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1.

[0043] Figure 14The images show multi-step It images obtained at different potentials for the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1. Detailed Implementation

[0044] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0045] Example 1

[0046] Preparation of MoS2 / Ni3S4 / CFP electrocatalysts with stable ampere-level current density:

[0047] (1) Preparation of precursor: 4 mmol NiCl2·6H2O, 9 mmol urea and 13 mmol ammonium fluoride were dissolved in 20 mL deionized water and stirred continuously until completely dissolved to obtain mixed solution A (the concentrations of NiCl2·6H2O, urea and ammonium fluoride in the solution were 0.2 mol / L, 0.45 mol / L and 0.65 mol / L, respectively). 18 mL of mixed solution A and carbon paper were placed in a hydrothermal reactor. The carbon paper (CFP) was immersed in the mixed solution A. After sealing, it was transferred to an oven and heated to 120 °C for 12 h. After the reaction was completed, the carbon paper was removed and cooled to room temperature. It was washed with anhydrous ethanol and deionized water in sequence and then dried in an oven at 60 °C for 8 h to obtain nickel hydroxide precursor.

[0048] (2) Preparation of catalyst: Take 1 mmol (NH4)6Mo7O 24 • 4H2O and 9 mmol thiourea were dissolved in 20 mL of deionized water and stirred continuously until completely dissolved to obtain mixed solution B (the solution contains (NH4)6Mo7O 24 With the concentrations of 4H2O and thiourea at 0.05 mol / L and 0.45 mol / L respectively, 18 mL of mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed, and transferred to an oven to be heated to 200 °C for 24 h. After the reaction was completed, the carbon paper was removed, and the resulting product was naturally cooled to room temperature. It was then washed successively with anhydrous ethanol and deionized water, and dried in an oven at 60 °C for 8 h to obtain a MoS2 / Ni3S4 / CFP electrocatalyst with an ampere-level current density stability.

[0049] Example 2

[0050] Preparation of MoS2 / Ni3S4 / CFP electrocatalysts with stable ampere-level current density:

[0051] (1) Preparation of precursor: 4 mmol Ni(NO3)2·6H2O, 8 mmol urea and 12 mmol ammonium fluoride were dissolved in 20 mL deionized water and stirred continuously until completely dissolved to obtain mixed solution A (the concentrations of Ni(NO3)2·6H2O, urea and ammonium fluoride in the solution were 0.2 mol / L, 0.4 mol / L and 0.6 mol / L, respectively). 18 mL of mixed solution A and carbon paper were placed in a hydrothermal reactor. The carbon paper was immersed in the mixed solution A. After sealing, it was transferred to an oven and heated to 110 °C for 10 h. After the reaction was completed, the carbon paper was removed and cooled to room temperature. It was washed with anhydrous ethanol and deionized water in sequence and then dried in an oven at 60 °C for 8 h to obtain nickel hydroxide precursor.

[0052] (2) Preparation of catalyst: 1 mmol MoCl5 and 8 mmol thiourea were dissolved in 20 mL of deionized water and stirred continuously until completely dissolved to obtain mixed solution B (the concentrations of MoCl5 and thiourea in the solution were 0.05 mol / L and 0.4 mol / L, respectively). 18 mL of mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed, and transferred to an oven and heated to 190 °C for 20 h. After the reaction was completed, the carbon paper was removed, cooled naturally to room temperature, washed with anhydrous ethanol and deionized water in sequence, and dried in an oven at 60 °C for 8 h to obtain a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density.

[0053] Example 3

[0054] Preparation of MoS2 / Ni3S4 / CFP electrocatalysts with stable ampere-level current density:

[0055] (1) Preparation of precursor: 4 mmol NiSO4·6H2O, 7 mmol urea and 11.5 mmol ammonium fluoride were dissolved in 20 mL deionized water and stirred continuously until completely dissolved to obtain mixed solution A (the concentrations of NiSO4·6H2O, urea and ammonium fluoride in the solution were 0.2 mol / L, 0.35 mol / L and 0.575 mol / L, respectively). 18 mL of mixed solution A and carbon paper were placed in a hydrothermal reactor. The carbon paper was immersed in the mixed solution A. After sealing, it was transferred to an oven and heated to 100 °C for 12 h. After the reaction was completed, the carbon paper was removed and the product was naturally cooled to room temperature. After washing with anhydrous ethanol and deionized water, it was dried in an oven at 60 °C for 8 h to obtain nickel hydroxide precursor.

[0056] (2) Preparation of catalyst: 1 mmol Na2MoO4·2H2O and 7 mmol thiourea were dissolved in 20 mL of deionized water and stirred continuously until completely dissolved to obtain mixed solution B (the concentrations of Na2MoO4·2H2O and thiourea in the solution were 0.05 mol / L and 0.35 mol / L, respectively). 18 mL of mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed, and transferred to an oven and heated to 180 °C for 24 h. After the reaction was completed, the carbon paper was removed, cooled naturally to room temperature, washed with anhydrous ethanol and deionized water in sequence, and dried in an oven at 60 °C for 8 h to obtain a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density.

[0057] Comparative Example 1

[0058] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, (NH4)6Mo7O is used in step (2). 24 The amount of 4H2O used was 0 mmol, and the rest of the preparation process and conditions were the same as in Example 1, thus obtaining the Ni3S4 / CFP composite nanoelectrode.

[0059] Comparative Example 2

[0060] The difference between Comparative Example 2 and Example 1 is that no nickel hydroxide precursor is added in step (2) of Comparative Example 2, while the rest of the preparation process and conditions are the same as those in Example 1, and a MoS2 / CFP composite nanoelectrode is obtained.

[0061] Comparative Example 3

[0062] Weigh 5 mg of commercial platinum-carbon catalyst (20%) and transfer 10 μL of Nafion solution (5%) and mix them together in 1 mL of mixed solution (H2O and EtOH volume ratio of 1:3) to form a Pt / C catalyst solution. After ultrasonic dispersion, drop the solution onto cleaned carbon paper several times with a pipette. After drying, a Pt / CFP electrode is obtained.

[0063] Comparative Example 4

[0064] The cleaned CFP is cut to electrode size to obtain the CFP electrode.

[0065] Material characterization analysis

[0066] (I) Scanning Electron Microscopy (SEM) Analysis

[0067] The surface morphology of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1 was characterized and analyzed using scanning electron microscopy (SEM). The characterization results are as follows: Figure 1 and 2 As shown. By Figure 1It can be observed at low magnification that the MoS2 / Ni3S4 nanoheterostructure is a three-dimensional nanopetal-like structure obtained by stacking ultrathin nanosheets, and it grows uniformly on carbon fibers. Figure 2 It can be observed under high magnification that the diameter of the three-dimensional MoS2 / Ni3S4 nanopetals is approximately 2–3 μm, and the surface is composed of ultrathin nanosheets. The three-dimensional nanopetal-like structure obtained by stacking ultrathin nanosheets has a large specific surface area, which is beneficial to the full contact between the catalyst and the electrolyte, and accelerates the electron and proton transfer efficiency.

[0068] (II) Transmission Electron Microscopy (TEM and HRTEM) Analysis

[0069] The microstructure of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1 was characterized and analyzed using transmission electron microscopy (TEM and HRTEM). The characterization results are as follows: Figure 3 and 4 As shown. By Figure 3 It can be seen that the structure of the ultrathin nanosheets can be observed by TEM, and MoS2 is present at the edges of the nanosheets. Figure 4 As can be seen from HRTEM, the lattice fringes of MoS2 and Ni3S4 can be observed, corresponding to the MoS2 (002) crystal plane and the Ni3S4 (400) crystal plane, respectively, and clear grain boundaries between the two phases can be seen, indicating that the heterojunction was successfully constructed.

[0070] (III) X-ray diffraction (XRD) analysis

[0071] The crystal structure of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1 was characterized by X-ray diffraction (XRD), and the characterization results are as follows: Figure 5 As shown. By Figure 5 It can be seen that crystal planes can be characterized by diffraction peaks at different incident angles. The XRD pattern of MoS2 / Ni3S4 / CFP shows that the diffraction peaks at 14.5°, 32.7°, and 58.3° correspond to the (002), (100), and (110) crystal planes of MoS2 (JCPDS Card No. 37-1492), while the six sharp diffraction peaks at 16.2°, 26.6°, 31.3°, 37.9°, 50.0°, and 54.7° correspond to the (111), (220), (311), (400), (511), and (440) crystal planes of Ni3S4 (JCPDS No. 47-1739). This indicates that Ni3S4 and MoS2 are present in MoS2 / Ni3S4 / CFP.

[0072] (iv) X-ray photoelectron spectroscopy (XPS) analysis

[0073] The surface composition and valence state of the MoS2 / Ni3S4 / CFP electrocatalyst prepared in Example 1 were determined and analyzed using X-ray photoelectron spectroscopy (XPS). The results are as follows: Figure 6 As shown. By Figure 6 (a) XPS full spectrum analysis reveals the presence of C, Mo, S, Ni, and O elements in MoS2 / Ni3S4; Figure 6 (b) The Ni 2p spectrum proves that Ni 2+ and Ni 3+ The presence of these ions, and the fact that Ni2p3 / 2 and 2p1 / 2 in MoS2 / Ni3S4 shift to higher binding energies compared to pure Ni3S4, indicates a higher valence state for Ni and a decrease in the electron cloud density around Ni; Figure 6 (b) The 3d spectrum of Mo proves that Mo 4+ The presence of these atoms, and the fact that the Mo 3d 3 / 2 and 3d 5 / 2 atoms in MoS2 / Ni3S4 shift to lower binding energies compared to pure MoS2, indicates a lower valence state of Mo and an increased electron cloud density around Mo; Figure 6 (d) The S2p spectrum proves that S 2- The presence of S, and the shift of S2p3 / 2 and 2p1 / 2 in MoS2 / Ni3S4 towards lower binding energies compared to pure MoS2, indicates a lower valence state of S and an increased electron cloud density around S. This change in electron cloud density is attributed to the electronegativity differences among Mo, Ni, and S. The introduction of Ni3S4 leads to a rearrangement of the electron cloud at the interface, resulting in a new hybrid structure.

[0074] Materials electrochemical testing and analysis

[0075] The electrochemical performance of the MoS2 / Ni3S4 / CFP electrocatalyst, Ni3S4 / CFP nanocomposite electrode, MoS2 / CFP nanocomposite electrode, Pt / CFP electrode, and CFP electrode prepared in Examples 1 and Comparative Examples 1-4 were tested and analyzed. The materials were tested using a CHI 660E and a Bio-Logic SAS electrochemical workstation, with a saturated calomel electrode as the reference electrode, a carbon rod as the counter electrode, and 1 mol / L KOH as the test electrolyte. The prepared samples were electrochemically tested using a three-electrode system at room temperature. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and chronoamperometry (It) were performed using the CHI 660E electrochemical workstation.

[0076] Before testing the samples, they were first activated for 100 cycles using cyclic voltammetry at a rate of 100 mV / s within a voltage range of -0.244 to 0.278 V. Cyclic voltammetry (CV) scans were performed on the samples in the electrolyte to obtain their cyclic voltammetric curves. The scan rate was 20–100 mV / s, and the voltage was 0.44–0.54 V vs. RHE. Electrochemically Active Surface Area (ECSA) images were plotted using CV plots. The ECSA images of the electrodes prepared in Example 1 and Comparative Examples 1-2 are shown below. Figure 7 , Figure 8 and Figure 9 As shown, the electrochemical double-layer capacitance (Cdl) of the material was estimated using CV plots and the image was plotted. The results are as follows. Figure 10 As shown. In comparison, the ECSA area of ​​the material in Example 1 is larger than that of other materials, and its Cdl value is significantly higher, at 71.8 mF / cm. 2 .

[0077] LSV was recorded at room temperature and a scan rate of 5 mV / s to obtain the polarization curve of HER, such as Figure 11 As shown, the Tafel slope is calculated from the LSV test results, as follows: Figure 12 As shown. In the hydrogen evolution reaction, Example 1 achieved 1 A / cm. 2 At a current density of , its overpotential is as low as 265mV, and the Tafel slope is 77mV / dec.

[0078] Stability was obtained by chronoamperometry (It), which involved adjusting the voltage of the sample from Example 1 until the current density was maintained at 1 A / cm². 2 A 100-hour stability test was conducted to evaluate HER performance, and the results are as follows: Figure 13 As shown, the sample still exhibits high activity after 100 hours of stability testing.

[0079] Meanwhile, to test the stability of the sample at different potentials, a multi-step chronoamperometry test was performed. The multi-step chronoamperometry test method involved adjusting the voltage of the sample from Example 1 to current densities of 200, 400, 600, 800, and 1000 mA / cm². 2 Among them, 200, 400, 600, 800, and 1000 mA / cm 2 This constitutes one test cycle, with each cycle lasting 12 hours. The cycle is repeated four times, for a total testing time of 48 hours. The results are as follows: Figure 14 As shown, this confirms that the sample can still maintain good stability under sudden voltage changes.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density, characterized in that, A heterogeneous interface is constructed between MoS2 and Ni3S4 via a hydrothermal reaction, and a heterojunction is formed between MoS2 and Ni3S4 on a carbon paper substrate, thus obtaining a MoS2 / Ni3S4 / CFP electrocatalyst with stable ampere-level current density. The ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst has a three-dimensional petal-like structure; The preparation method of the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst includes the following steps: (1) Preparation of precursor: Nickel salt, urea and ammonium fluoride were dissolved in water and stirred continuously until completely dissolved to obtain mixed solution A. Mixed solution A and carbon paper were placed in a hydrothermal reactor, sealed and transferred to an oven for a hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled naturally to room temperature. After washing and drying, nickel hydroxide precursor was obtained. (2) Preparation of catalyst: Molybdenum salt and thiourea were dissolved in water and stirred until completely dissolved to obtain mixed solution B. Mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed and transferred to an oven for a second hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled to room temperature naturally. After washing and drying, a MoS2 / Ni3S4 / CFP electrocatalyst with stable current density at the ampere level was obtained. The molybdenum salt is (NH4)6Mo7O 24 • 4H2O, MoCl5 or Na2MoO4•2H2O; The molar ratio of molybdenum salt to thiourea is 1:7-9; the concentrations of molybdenum salt and thiourea in the mixed solution B are 0.05 mol / L and 0.35-0.45 mol / L, respectively. The secondary hydrothermal reaction is carried out at a temperature of 180–200°C for 22–24 hours.

2. A method for preparing the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of precursor: Nickel salt, urea and ammonium fluoride were dissolved in water and stirred continuously until completely dissolved to obtain mixed solution A. Mixed solution A and carbon paper were placed in a hydrothermal reactor, sealed and transferred to an oven for a hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled naturally to room temperature. After washing and drying, nickel hydroxide precursor was obtained. (2) Preparation of catalyst: Molybdenum salt and thiourea were dissolved in water and stirred until completely dissolved to obtain mixed solution B. Mixed solution B and nickel hydroxide precursor were placed in a hydrothermal reactor, sealed and transferred to an oven for a second hydrothermal reaction. After the reaction was completed, the carbon paper was taken out and cooled to room temperature naturally. After washing and drying, a MoS2 / Ni3S4 / CFP electrocatalyst with stable current density at the ampere level was obtained. The molybdenum salt is (NH4)6Mo7O 24 • 4H2O, MoCl5 or Na2MoO4•2H2O; The molar ratio of molybdenum salt to thiourea is 1:7-9; the concentrations of molybdenum salt and thiourea in the mixed solution B are 0.05 mol / L and 0.35-0.45 mol / L, respectively. The secondary hydrothermal reaction is carried out at a temperature of 180–200°C for 22–24 hours.

3. The preparation method of the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst according to claim 2, characterized in that, In step (1), the nickel salt is NiCl2·6H2O, Ni(NO3)2·6H2O or NiSO4·6H2O.

4. The method for preparing the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst according to claim 3, characterized in that, In step (1), the molar ratio of nickel salt, urea and ammonium fluoride is 4:7-9:11.5-13; the concentrations of nickel salt, urea and ammonium fluoride in the mixed solution A are 0.2 mol / L, 0.35-0.45 mol / L and 0.575-0.65 mol / L, respectively.

5. The method for preparing the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst according to claim 2, characterized in that, In step (1), the hydrothermal reaction is carried out at a temperature of 100-120°C for 10-12 hours.

6. The application of the ampere-level current density-stable MoS2 / Ni3S4 / CFP electrocatalyst as described in claim 1 in the hydrogen evolution reaction.

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