Heterostructure electrocatalyst and preparation method and application thereof

Abstract

This invention discloses a heterostructured electrocatalyst, its preparation method, and its applications, belonging to the field of catalyst technology. The method includes the following steps: mixing MoS2 powder and nickel powder, followed by mechanochemical ball milling under an inert atmosphere to obtain the heterostructured electrocatalyst. The method provided by this invention can achieve integrated structural control and metal doping at room temperature and pressure, thereby significantly improving the hydrogen evolution activity and stability of the material in alkaline media. Furthermore, this invention has industrial advantages such as low energy consumption, no pollution, and simple post-processing, providing a new pathway for the large-scale preparation of high-performance, low-cost hydrogen energy materials.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and particularly relates to a heterostructure electrocatalyst, its preparation method and application. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental problems, advancements in clean and sustainable energy conversion technologies have become imperative. Hydrogen (H2) is considered a key direction for future energy system transformation due to its high energy density, zero carbon emissions, and sustainability. Electrochemical water splitting for hydrogen production is one of the most promising hydrogen production methods due to its environmental friendliness and high product purity. The key to breakthroughs in this technology lies in developing hydrogen evolution reaction (HER) electrocatalysts that combine high catalytic activity, low manufacturing costs, and long-term operational stability to achieve the dual goals of reducing energy consumption and improving energy conversion efficiency. Currently, platinum (Pt)-based catalysts are considered among the most effective HER catalysts due to their excellent catalytic performance; however, the scarcity and high cost of platinum severely limit its large-scale application. Therefore, current efforts focus on developing efficient, stable, and low-cost HER electrocatalysts.

[0003] Among numerous candidate materials, molybdenum disulfide (MoS2) is considered a potential Pt substitute due to its unique two-dimensional layered structure, suitable hydrogen adsorption free energy, and excellent chemical stability. However, the poor conductivity and limited active sites of intrinsic MoS2 restrict further improvement of its catalytic performance. To address these challenges, a series of modification strategies have been proposed in the prior art, including phase engineering, construction of heterojunctions, introduction of defects, and doping with metal species. However, these strategies are often constrained in their transition from laboratory to industrial applications due to cumbersome preparation steps, high energy consumption, and difficulty in scaling up.

[0004] Therefore, how to provide a synthesis technology that combines the advantages of simple process, low energy consumption and scalability to synergistically regulate the structure and electronic properties of MoS2 is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a heterostructure electrocatalyst, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a heterostructured electrocatalyst includes the following steps: The heterostructured electrocatalyst is obtained by mixing MoS2 powder and nickel powder and then subjecting them to mechanochemical ball milling under an inert atmosphere.

[0007] Beneficial Effects: High-energy ball milling is characterized by its efficiency, scalability, reliability, and environmental friendliness. The intense collision and shear forces of high-energy spheres can achieve atomic-level close composite formation of non-uniform materials, forming strong interfacial bonds. The method provided by this invention can achieve integrated structural regulation and metal doping at room temperature and pressure, thereby significantly improving the hydrogen evolution activity and stability of materials in alkaline media. This invention achieves multi-effect synergistic regulation of composite materials through mechanochemical processes and simultaneously induces the formation of sulfur vacancy defects on the MoS2 basal surface during the atomic-level coupling process of heterogeneous components (Ni-MoS2). The synergistic effect of defect generation and pinning by Ni nanoparticles can activate the inert MoS2 basal surface, forming more active sites that can participate in the reaction. The resulting "pinning effect" and abundant vacancies not only promote the formation of Mott-Schottky junctions with built-in electric fields but also enhance the Ni-S interface. These features collectively regulate the electronic structure, accelerate H2O dissociation kinetics, promote hydrogen overflow from Ni to MoS2, and synergistically enhance HER activity. This mechanochemical mechanism synergistically optimizes the electron transport pathway and active site distribution, providing a structural basis for improving catalytic performance.

[0008] Preferably, the mass ratio of MoS2 powder to nickel powder is (0.8-0.95):(0.2-0.05).

[0009] More preferably, the mass ratio of MoS2 powder to nickel powder is 0.9:0.1.

[0010] Preferably, the ball milling speed is 1000 rpm and the time is 0.5-6 hours, more preferably 4 hours.

[0011] Preferably, the ball milling medium is stainless steel balls, and the ball-to-material ratio is 60:1.

[0012] Preferably, the inert atmosphere is an argon atmosphere.

[0013] A heterostructured electrocatalyst prepared by the method described above.

[0014] Preferably, the heterostructured electrocatalyst comprises defective molybdenum disulfide and nickel nanoparticles pinned to the defective molybdenum disulfide.

[0015] Application of a heterostructured electrocatalyst in electrocatalytic hydrogen evolution.

[0016] An electrode for electrocatalytic hydrogen evolution includes the aforementioned heterostructure electrocatalyst.

[0017] A method for preparing an electrode for electrocatalytic hydrogen evolution includes the following steps: The heterostructured electrocatalyst is dispersed in a mixed solution of deionized water and ethanol, and then Nafion solution is added for ultrasonic dispersion to obtain a uniformly dispersed catalyst slurry. The catalyst slurry is then drop-coated onto the surface of an electrode substrate to obtain the electrode used for electrocatalytic hydrogen evolution.

[0018] More preferably, the electrode substrate is a glassy carbon electrode substrate.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: This invention employs a unique one-step mechanochemical-induced phase transition, utilizing the mechanical shear force generated by high-energy ball milling and the electronic induction effect of metallic Ni to simultaneously achieve the topological transformation of MoS2 from a semiconducting (2H phase) to a metallic (1T phase) phase at room temperature and pressure. This spontaneous phase transition significantly enhances the intrinsic conductivity of the substrate, which is impossible to achieve with conventional powder loading processes. Based on the preparation method of this invention, it exhibits extremely high atomic utilization and active site exposure. The one-step ball milling strategy, while exfoliating MoS2 nanosheets, effectively prevents secondary stacking of nanosheets using metallic Ni as a "spacer," significantly increasing the electrochemically active specific surface area and allowing active sites to be fully exposed in three-dimensional space. Simultaneously, the catalyst obtained by this invention forms a strongly interacting "defect-pinning" structure. Unlike the loose surface loading in catalysts obtained by traditional techniques, this invention uses sulfur vacancies generated by mechanochemical reactions to form a strong physical-chemical dual pinning of metallic Ni nanoparticles. This strong metal-support interaction not only prevents the aggregation and detachment of active sites during the intense hydrogen evolution process but also ensures the long-term electrochemical stability of the catalyst. Furthermore, the obtained catalyst possesses abundant active sites and an optimized electronic structure, with the synergistic effect of doping and defects significantly optimizing hydrogen adsorption activity and electron transport pathways. In addition, the catalyst obtained in this invention exhibits an optimized Mott-Schottky heterostructure interface. Through energy level matching between metallic Ni and defective MoS2, a Mott-Schottky barrier with a built-in electric field is constructed at the interface. This interface effect induces the directional transfer of electrons from Ni to MoS2, optimizing the hydrogen adsorption free energy of the active sites and significantly accelerating the Volmer step (water dissociation) kinetics in basic HER. Finally, this invention employs a dry process throughout, eliminating the need for high temperature, high pressure, or organic solvents, offering industrial advantages such as low energy consumption, no pollution, and simple post-processing, providing a new pathway for the large-scale preparation of high-performance, low-cost hydrogen energy materials. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1The image shows the XRD pattern of the heterostructure catalyst obtained in Example 1 of this invention. Figure 2 This is a TEM image of the heterostructure catalyst obtained in Example 1 of the present invention; Figure 3 The energy dispersive spectroscopy (EDS) mapping of Ni element in the heterostructure catalyst obtained in Example 1 of this invention is shown. Figure 4 Here is an HRTEM electron microscope image of the heterostructure catalyst obtained in Example 1 of this invention; Figure 5 The LSV diagrams are of the catalysts obtained in Examples 1-7 of this invention; Figure 6 The LSV diagrams are of the heterostructure catalysts obtained in Example 1 and Comparative Examples 1-4 of this invention. Figure 7 The results show the long-term stability test results of the heterostructure catalyst obtained in Example 1 of this invention. Figure 8 The Mott-Schottky curves of the heterostructure catalyst obtained in Example 1 of this invention at different frequencies are shown. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels; Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0024] Example 1 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 4 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0025] Example 2 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 0.5 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0026] Example 3 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 1 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0027] Example 4 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding media (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 2 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0028] Example 5 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 6 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0029] Example 6 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.95:0.05. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding media (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 4 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0030] Example 7 A method for preparing a heterostructured electrocatalyst includes the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.8:0.2. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 4 h. After ball milling, a heterostructured electrocatalyst was obtained.

[0031] Comparative Example 1 The only difference from Example 1 is that the metallic Ni powder is replaced with an equal mass of MoS2 powder, specifically including the following steps: 1g of commercial MoS2 powder was weighed and placed in a stainless steel ball mill jar. Stainless steel balls were added as the grinding medium (ball-to-powder ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode was 30 min working and 30 min resting, with a total ball milling time of 4 h. After ball milling, the catalyst was obtained.

[0032] Comparative Example 2 The only difference from Example 1 is that the MoS2 powder is replaced with an equal mass of metallic Ni powder, specifically including the following steps: 1g of metallic Ni powder was weighed and placed in a stainless steel ball mill jar. Stainless steel balls were added as the grinding medium (ball-to-powder ratio of 60:1). High-energy ball milling was carried out under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode was 30 min working and 30 min resting, with a total ball milling time of 4 h. After ball milling, the catalyst was obtained.

[0033] Comparative Example 3 The only difference from Example 1 is that MoS2 powder and metallic Ni powder are mixed at a MoS2:Ni mass ratio of 0.6:0.4, specifically including the following steps: 1 g of commercially available MoS2 powder and 1 g of metallic Ni powder were weighed and mixed at a MoS2:Ni mass ratio of 0.6:0.4. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-powder ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 4 h. After ball milling, the catalyst was obtained.

[0034] Comparative Example 4 The only difference from Example 1 is that the metallic Ni powder is replaced with another Ni source (NiO), specifically including the following steps: 1 g of MoS2 powder and 1 g of Ni source (NiO) were weighed and mixed at a mass ratio of 0.9:0.1. The mixture was then placed in a stainless steel ball mill jar, and stainless steel balls were added as the grinding medium (ball-to-material ratio of 60:1). High-energy ball milling was performed under argon protection. The ball mill speed was 1000 rpm, and the intermittent operation mode consisted of 30 min of operation followed by 30 min of rest, for a total ball milling time of 4 h. After ball milling, the catalyst was obtained.

[0035] Technical effects: 1. Structural characterization The powder obtained in Example 1 was analyzed by powder X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown, in addition to the (002) diffraction peak of MoS2, diffraction peaks belonging to Ni were also observed, indicating that MoS2 and Ni formed a composite material after ball milling.

[0036] The product powder was characterized using transmission electron microscopy (TEM), and the results are as follows: Figure 2 As shown, after high-energy ball milling, some MoS2 particles are exfoliated to form thin nanosheets. This deep exfoliation effectively increases the specific surface area of ​​the catalyst and provides more pinning sites for metallic Ni.

[0037] Energy dispersive spectroscopy (EDS) mapping was performed on the product powder, and the results are as follows: Figure 3 As shown, the energy spectrum distribution of Ni elements indicates that Ni particles are uniformly embedded in the MoS2 nanosheet substrate.

[0038] Transmission electron microscopy analysis is as follows: The product powder was characterized using high-resolution transmission electron microscopy (HRTEM), and the results are as follows. Figure 4 As shown, clear lattice fringes with an interplanar spacing of 0.63 nm were observed, corresponding to the (002) crystal plane of MoS2. Furthermore, lattice fringes corresponding to the Ni (111) crystal plane were identified on the MoS2 substrate, and Ni nanoparticles with a size range of approximately 3–5 nm (purple region) were clearly observed in the HRTEM image. The uniformly dispersed Ni species provide abundant active sites for the hydrogen evolution reaction.

[0039] The above data analysis confirms that the heterojunction catalyst obtained in this invention includes defective MoS2, and Ni particles are uniformly embedded in the defects of MoS2, forming a strongly interacting "defect-pinning" structure, which is a strong physical-chemical double pinning.

[0040] 2. Electrochemical performance testing Preparation of the working electrode: 6.0 mg of the catalysts obtained in Examples 1-7 and Comparative Examples 1-4 were weighed and dispersed in 1 mL of a mixed solution of deionized water and ethanol (volume ratio 1:1). Then, 50 μL of Nafion (5 wt%) solution was added, and the mixture was ultrasonically dispersed for at least 1 hour to obtain a uniform catalyst slurry. 4 μL of the catalyst slurry was drop-coated onto the surface of a glassy carbon electrode with a diameter of 5 mm and dried to serve as the working electrode.

[0041] Electrochemical tests were performed on a CHI660E electrochemical workstation using a conventional three-electrode system. The working electrode was a glassy carbon electrode coated with the catalysts obtained in Examples 1-7 and Comparative Examples 1-4, respectively. A glassy carbon electrode without catalyst coating was used as a blank control group. The reference electrode was Hg / HgO (1 M KOH). The counter electrode was a graphite rod. The electrolyte was a 1.0 M KOH solution. All potentials were converted to their potentials relative to the reversible hydrogen electrode (RHE) using the following formula: E(vs.RHE)=E(vs.Hg / HgO)+0.098+0.059×pH.

[0042] All polarization curves were corrected for IR compensation.

[0043] Under the condition of using 1.0 M KOH solution as electrolyte, at 5 mV·s -1Linear scan voltammetry (LSV) was performed at the scan rate, and the results are as follows: Figure 5-6 As shown, Example 1 exhibits the best HER catalytic activity at 10 mAcm⁻¹. -2 The overpotential is 130 mV.

[0044] The stability test of the catalyst obtained in Example 1 further confirmed its excellent durability, under the condition of using 1.0 M KOH solution as the electrolyte at 500 mA cm⁻¹. -2 The current density was subjected to a long-term constant current test, and the results are as follows: Figure 7 As shown, it can be seen that at 500 mA cm -2 After running continuously at a high current density for 12 hours, the catalyst obtained in Example 1 did not show significant performance degradation. Thanks to the "defect-pinning" structure, the catalytic active sites exhibited excellent stability during the intense hydrogen evolution process.

[0045] like Figure 8 As shown, the Mott-Schottky test results of the catalyst obtained in Example 1 show that the curve exhibits a positive slope and a flat band potential of -0.79 eV. This positive slope characteristic, together with the specific flat band potential value, confirms the successful formation of the Mott-Schottky heterojunction.

[0046] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a heterostructured electrocatalyst, characterized by, Includes the following steps: The heterostructured electrocatalyst is obtained by mixing MoS2 powder and nickel powder and then subjecting them to mechanochemical ball milling under an inert atmosphere.

2. The method of claim 1, wherein the heterostructured electrocatalyst is prepared by the steps of: The mass ratio of MoS2 powder to nickel powder is (0.8-0.95):(0.2-0.05).

3. The method of claim 1, wherein the heterostructured electrocatalyst is prepared by the steps of: The ball mill operates at a speed of 1000 rpm for 0.5-6 hours.

4. The method of claim 1, wherein the heterostructured electrocatalyst is prepared by the steps of: The ball milling medium is stainless steel balls, and the ball-to-material ratio is 60:

1.

5. The method for preparing the heterostructured electrocatalyst according to claim 1, characterized in that, The inert atmosphere is an argon atmosphere.

6. A heterostructured electrocatalyst prepared by the preparation method according to any one of claims 1-5.

7. The heterostructured electrocatalyst according to claim 6, characterized in that, The heterostructured electrocatalyst comprises defective MoS2 and nickel nanoparticles pinned to the defective MoS2.

8. The application of a heterostructure electrocatalyst as described in claim 6 or 7 in electrocatalytic hydrogen evolution.

9. An electrode for electrocatalytic hydrogen evolution, characterized in that, Including the heterostructured electrocatalyst as described in claim 6 or 7.

10. A method for preparing an electrode for electrocatalytic hydrogen evolution as described in claim 9, characterized in that, Includes the following steps: The heterostructured electrocatalyst is dispersed in a mixed solution of deionized water and ethanol, and then Nafion solution is added for ultrasonic dispersion to obtain a catalyst slurry. The catalyst slurry is then drop-coated onto the surface of an electrode substrate to obtain the electrode used for electrocatalytic hydrogen evolution.

Images