MoS2 (1-x) Se2x nanosheet array and preparation method thereof

Abstract

The invention provides a method for preparing a MoS2 (1-x) Se2x nanosheet array and a preparation method of the MoS2 (1-x) Se2x nanosheet array. The preparation method comprises the following steps: placing a raw material and a substrate in a closed environment, wherein the substrate is located above the raw material; wherein the raw materials are elemental sulfur, elemental selenium and molybdenum trioxide; applying a magnetic field in the closed environment, and placing the raw materials in the magnetic field; after the reaction lasts for a preset time, stopping loading the magnetic field; after cooling, the MoS2 (1-x) Se2x nanosheet array growing in situ can be obtained, and the MoS2 (1-x) Se2x nanosheet array is located on the surface of the substrate. Compared with the prior art, the method has the advantages that the used equipment is simpler, the reaction time is obviously shortened, and the preparation efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of chemical preparation, and more particularly to a MoS2O3 solution. 2(1-x) Se 2x Nanosheet arrays and their preparation methods. Background Technology

[0002] Transition metal dichalcogenides (TMDs) are considered promising catalysts for the hydrogen evolution reaction (HER) due to their abundant edge active sites and extremely high interlayer electron mobility. Among two-dimensional layered TMDs, molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) not only possess electronic structures similar to noble metals but also have the advantages of easy synthesis and tunable structure, making them systems of great interest in HER electrocatalysis research. The catalytic activity of TMD materials is mainly concentrated at the edges, while the basal surface usually exhibits catalytic inertness. To address this, common performance optimization strategies include constructing more edge structures through edge engineering and activating basal surface activity through disorder engineering. However, these strategies often lead TMD materials to form smaller nanostructures or metastable phases, making it difficult to maintain a complete crystal framework, thus affecting material stability and hindering their industrial application. In addition, at high current densities, the cavitation erosion effect induced by hydrogen bubbles can also significantly reduce the catalyst's lifetime.

[0003] To improve the hydrogen adsorption free energy (HER) performance of MoS2, researchers have developed various composite preparation methods. Among them, MoS2 substitution-doped composites introduce elements from the same group to replace the original Mo or S sites, thereby controlling the material composition to optimize its active centers and electronic structure. Theoretical calculations show that the hydrogen adsorption free energy (ΔGH) at the edge of MoS2 is... = 0.08 Ev) is too weak, which is not conducive to the effective adsorption of reactants; while the ΔG at the edge of MoSe2 is weak. H (-0.14 eV) is too strong and can easily lead to the blockage of active sites. Therefore, ΔG H Adjusting the voltage to near 0 eV has become one of the key strategies for improving the HER catalytic performance of TMDs materials. Since MoS2 and MoSe2 have similar crystal structures, introducing Se to partially replace S can achieve ΔG while continuously controlling the d-band electronic structure of Mo. H The controllable adjustment of the electrocatalytic activity significantly enhances the electrocatalytic activity. Studies have shown that anion substitution doping of MoS2 can form MoS2. 2(1-x) Se 2x This allows for the construction of alternating symmetric structures with abundant active sites, further enhancing HER performance. Furthermore, due to the structural similarity between MoS2 and MoSe2, the resulting MoS... 2(1-x) Se2x The crystal undergoes only slight lattice distortion and typically exhibits good structural stability during catalysis.

[0004] Nevertheless, achieving high-quality MoS 2(1-x) Se 2x The large-scale fabrication of nanosheet arrays remains challenging. Furthermore, when used as HER catalysts, this material system often struggles to balance low overpotential and high stability, limiting its further practical applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a MoS2 2(1-x) Se 2x A method for fabricating nanosheet arrays. This method enables the large-scale fabrication of anion-substituted MoS₂ on a substrate. 2(1-x) Se 2x Nanosheet array.

[0006] The technical solution of the present invention is as follows: A MoS 2(1-x) Se 2x The method for preparing nanosheet arrays includes the following steps: The raw materials and the substrate are placed in a sealed environment, with the substrate positioned above the raw materials; wherein the raw materials are elemental sulfur, elemental selenium, and molybdenum trioxide. A magnetic field is applied in the sealed environment, so that the raw material is placed in the magnetic field; After the reaction has continued for a predetermined time, the magnetic field is stopped. After cooling, the in-situ grown MoS₂ can be obtained. 2(1-x) Se 2x Nanosheet array, the MoS 2(1-x) Se 2x The nanosheet array is located on the surface of the substrate.

[0007] In this method, a mixture of molybdenum trioxide and sulfur / selenium is used as a precursor, and a molybdenum sheet is used as an inductive heat source to achieve in-situ growth of nanosheets in a vacuum magnetic levitation induction furnace. By applying an alternating magnetic field, eddy currents are induced in the molybdenum sheet, causing it to rapidly heat up and heat the surrounding reactants. Molybdenum trioxide, sulfur, and selenium are transported to the substrate surface under the drive of the magnetic field, thereby promoting the growth of MoS2 nanosheets. 2(1-x) Se 2x Nanosheets rapidly nucleate and grow on the substrate. It should be noted that the magnetic field can be generated in various ways, such as through electromagnetic coils or permanent magnets.

[0008] The strength of the magnetic field is between 1 mT and 1 T.

[0009] The predetermined time is no less than 5 seconds.

[0010] The vacuum level of the sealed environment is less than 10 kPa.

[0011] The molar ratio of elemental sulfur (S / Se) to elemental selenium in the reaction raw materials is controlled to be below 10.

[0012] The purity of both sulfur and selenium is not less than 80%.

[0013] The temperature of the substrate is not higher than 1800 degrees.

[0014] The substrate is disposed on the sidewall of the sealed environment.

[0015] A molybdenum sheet is placed above the raw material, which causes the magnetic field lines to deflect.

[0016] A MoS 2(1-x) Se 2x Nanosheet arrays grown on the substrate in a vertical orientation.

[0017] The beneficial effects of this invention include: (1) Compared with the prior art, the equipment used in this invention is simpler, the reaction time is significantly shortened, and the preparation efficiency is high.

[0018] (2) The obtained MoS 2(1-x) Se 2x The nanosheet array exhibits excellent crystal quality, and the thickness of the nanosheets can be controlled by adjusting the magnetic field strength and reaction time, resulting in products with superior physical properties.

[0019] (3) This method can realize the in-situ growth of nanosheet arrays on the substrate, and has good scientific research applicability and industrialization potential. Attached Figure Description

[0020] Figure 1 MoS of the present invention 2(1-x) Se 2x A schematic diagram of the fabrication method of nanosheet arrays.

[0021] Figure 2 MoS2 obtained in Example 1 2(1-x) Se 2x SEM image of the nanosheet array.

[0022] Figure 3 MoS2 obtained in Example 2 2(1-x) Se 2x Raman diagram of nanosheet array.

[0023] Figure 4 MoS2 obtained in Example 1 2(1-x) Se2x Nanosheet array at 100 mA·cm -2 The test diagram shows the stable operation for 100 hours under the specified current density. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Unless otherwise specified, all raw materials and reagents used in this invention are commercially available.

[0026] See Figure 1 This invention provides a MoS 2(1-x) Se 2x The method for preparing nanosheet arrays includes the following steps: The raw materials and the substrate are placed in a sealed environment, with the substrate positioned above the raw materials; wherein the raw materials are elemental sulfur, elemental selenium, and molybdenum trioxide. A magnetic field is applied in the sealed environment, so that the raw material is placed in the magnetic field; After the reaction has continued for a predetermined time, the magnetic field is stopped. After cooling, the in-situ grown MoS₂ can be obtained. 2(1-x) Se 2x Nanosheet array, the MoS 2(1-x) Se 2x The nanosheet array is located on the surface of the substrate.

[0027] like Figure 1 As shown, the raw materials (elemental sulfur, elemental selenium, and molybdenum trioxide) are placed in a crucible, which is then placed in a magnetic levitation melting furnace. A layer of molybdenum sheet is then placed on top of the crucible, and a substrate (in this embodiment, the substrate is a molybdenum mesh) is placed on the side wall of the magnetic levitation melting furnace. After that, the magnetic levitation melting furnace is turned off, and a magnetic field is generated by using an electric current.

[0028] Example 1 This embodiment uses a magnetic levitation melting furnace, utilizing electric current to generate an electromagnetic field. The specific steps are as follows: (1) Weigh out 0.151 g of elemental sulfur, 0.302 g of elemental selenium, 0.02 g of molybdenum trioxide and 5.633 g of molybdenum sheet respectively, place them in a crucible, and put the crucible into a vacuum magnetic levitation melting furnace.

[0029] (2) The furnace current is set to 30 A and the reaction time is 60 s, corresponding to a magnetic field strength of approximately 0.03 T.

[0030] (3) Use nitrogen to purge the furnace cavity three or more times to maintain a vacuum environment and start the reaction.

[0031] (4) After the reaction is completed, MoS2 is obtained in situ grown on the surface of the molybdenum mesh after cooling treatment. 2(1-x) Se 2x Nanosheet array.

[0032] Figure 2 Image (a) shows the SEM morphology of the sample obtained in Example 1. It can be observed from the image that a large amount of MoS₂ has grown in situ and uniformly on the surface of the molybdenum mesh. 2(1-x) Se 2x Nanosheets form a regularly arranged nanoarray structure. Figure 2 (bd) is a magnified image of a portion of the nanosheet array, clearly showing MoS2. 2(1-x) Se 2x The nanosheets are grown perpendicular to the substrate and exhibit an ultrathin morphology.

[0033] Example 2 (1) Weigh out 0.308 g of elemental sulfur, 0.654 g of elemental selenium, 0.03 g of molybdenum trioxide and 5.865 g of molybdenum sheet respectively, place them in a crucible, and put the crucible into a vacuum magnetic levitation melting furnace.

[0034] (2) The current is set to 35 A, the reaction time is 90 s, and the corresponding magnetic field strength is about 0.04 T.

[0035] (3) The furnace cavity is purged with argon gas three times or more to maintain vacuum conditions before the reaction begins.

[0036] (4) After the reaction is completed and cooled, in-situ grown MoS2 is obtained on the surface of the molybdenum mesh. 2(1-x) Se 2x Nanosheet array.

[0037] Figure 3 The above are the EDS energy dispersive spectroscopy analysis results of the sample obtained in Example 2. This analysis shows that MoS₂... 2(1-x) Se 2x The nanosheet array is composed of three elements: Mo, S, and Se. The mass fractions of S and Se are 13.9% and 25.4%, respectively, and the S / Se molar ratio is approximately 1:1. Based on this, its composition corresponds to Mo(S) 0.5 Se 0.5 2. Furthermore, the EDS elemental distribution results show that Mo, S, and Se are uniformly distributed throughout the nanosheets, further confirming the uniform doping of elements in the material.

[0038] Example 3 (1) Weigh out 0.654 g of elemental sulfur, 0.468 g of elemental selenium, 0.08 g of molybdenum trioxide and 5.562 g of molybdenum sheet respectively, place them in a crucible, and then place the crucible into a vacuum magnetic levitation melting furnace.

[0039] (2) The current is set to 20 A and the reaction time is 120 s, which corresponds to a magnetic field strength of approximately 0.02 T.

[0040] (3) Purge the furnace cavity with argon gas three times or more to maintain a vacuum environment and start the reaction.

[0041] (4) After the reaction is completed and cooled, in-situ grown MoS2 is obtained on the surface of the molybdenum mesh. 2(1-x) Se 2x Nanosheet array.

[0042] Example 4 (1) Weigh out 1.552 g of elemental sulfur, 1.476 g of elemental selenium, 0.1 g of molybdenum trioxide and 5.851 g of molybdenum sheet respectively, place them in a crucible, and put the crucible into a vacuum magnetic levitation melting furnace.

[0043] (2) The current is set to 10 A, the reaction time is 50 minutes, and the corresponding magnetic field strength is 0.01 T.

[0044] (3) Purge the furnace cavity with nitrogen three times or more to maintain vacuum conditions before starting the reaction.

[0045] (4) After the reaction is completed and cooled, in-situ grown MoS2 is obtained on the surface of the molybdenum mesh. 2(1-x) Se 2x Nanosheet array.

[0046] Example 5 (1) Weigh out 0.255 g of elemental sulfur, 0.247 g of elemental selenium, 0.01 g of molybdenum trioxide and 5.404 g of molybdenum sheet respectively, place them in a crucible, and then place the crucible into a vacuum magnetic levitation melting furnace.

[0047] (2) The current is set to 100 A and the reaction time is 1 minute, which corresponds to a magnetic field strength of about 1 T.

[0048] (3) Purge the furnace cavity with nitrogen three times or more to maintain a vacuum environment and start the reaction.

[0049] (4) After the reaction is completed and cooled, in-situ grown MoS2 is obtained on the surface of the molybdenum mesh. 2(1-x) Se 2x Nanosheet array.

[0050] This invention proposes a fabrication technique called "magnetic planting" (PDMF), which enables the large-scale fabrication of anion-substituted MoS2 on molybdenum grids. 2(1-x) Se2x Nanosheet arrays. These arrays are grown on a substrate in a vertical orientation, which helps mitigate the damage to the electrode structure caused by hydrogen cavitation. Furthermore, by adjusting the molar ratio of (S+Se) / Mo in the reactants, abundant fractal structures can be induced in the edge regions of the nanosheets. This method exhibits good scalability and is applicable to various scenarios, from laboratory research to large-scale production.

[0051] MoS obtained in Example 1 2(1-x) Se 2x HER performance testing was performed on nanosheet arrays. Figure 4 HER performance tests showed that the sample prepared in Example 1 performed well at 100 mA·cm⁻¹. -2 The overpotential at this high current density is only 248 mV, and it can operate stably for over 100 hours under this high current condition, demonstrating excellent catalytic durability. Analysis of the post-reaction electrode further confirms that MoS2... 2(1-x) Se 2x The overall structure of the nanosheet array remains intact, with only the edge regions becoming smoother due to the reaction process.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0053] The parts of this invention not described in detail are well-known in the art. The above embodiments are provided merely for the purpose of describing the invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A MoS 2(1-x) Se 2x A method for preparing nanosheet arrays, characterized in that, Includes the following steps: The raw materials and the substrate are placed in a sealed environment, with the substrate positioned above the raw materials; wherein the raw materials are elemental sulfur, elemental selenium, and molybdenum trioxide. A magnetic field is applied in the sealed environment, so that the raw material is placed in the magnetic field; After the reaction has continued for a predetermined time, the magnetic field is stopped. After cooling, the in-situ grown MoS₂ can be obtained. 2(1-x) Se 2x Nanosheet array, the MoS 2(1-x) Se 2x The nanosheet array is located on the surface of the substrate.

2. The preparation method according to claim 1, characterized in that, The magnetic field is an alternating magnetic field, and the strength of the magnetic field is from 1 mT to 1 T.

3. The preparation method according to claim 1, characterized in that, The predetermined time is no less than 5 seconds.

4. The preparation method according to claim 1, characterized in that, The vacuum level of the sealed environment is less than 10 kPa.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The molar ratio of elemental sulfur to elemental selenium (S / Se) in the reaction feedstock is controlled to be below 10.

6. The preparation method according to claim 5, characterized in that, The purity of both the sulfur and selenium is not less than 80%.

7. The preparation method according to claim 1, characterized in that, The temperature of the substrate is not higher than 1800 degrees.

8. The preparation method according to claim 7, characterized in that, The substrate is disposed on the sidewall of the enclosed environment.

9. The preparation method according to claim 8, characterized in that, A molybdenum sheet is also disposed above the raw material, which causes the magnetic field lines to deflect.

10. A MoS2 2(1-x) Se 2x Nanosheet array, characterized in that, The MoS2 as described in any one of claims 1 to 9 2(1-x) Se 2x The MoS2 nanosheet array was prepared using a specific method. 2(1-x) Se 2x The nanosheet array is grown on the substrate in a vertical orientation.

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