An ultra-dispersed rare earth doped MoSe2 material, a preparation method and application thereof

Abstract

This invention relates to the field of electrocatalytic hydrogen production technology, and particularly to a highly dispersed rare-earth-doped MoSe2 material, its preparation method, and its applications. The preparation method of the highly dispersed rare-earth-doped MoSe2 material includes: S1) mixing solution A and solution B to obtain an emulsion; solution A is obtained by mixing a selenium source and hydrazine hydrate; solution B is obtained by mixing a molybdenum source and an aqueous solvent; the aqueous solvent is composed of water and dopamine; S2) mixing a rare-earth dopant with the emulsion, ultrasonically dispersing it uniformly, and then heating it to perform a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain the highly dispersed rare-earth-doped MoSe2 material. The highly dispersed rare-earth-doped MoSe2 material prepared by this invention exhibits superior catalytic activity in electrocatalytic hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic hydrogen production technology, and in particular to an ultradispersed rare earth-doped MoSe2 material, its preparation method and application. Background Technology

[0002] Due to the increasing severity of energy problems related to energy security and environmental pollution, hydrogen, with its high energy density and zero greenhouse gas emissions, has been widely recognized as an ideal alternative fuel to alleviate the future global energy crisis. The electrochemical hydrogen evolution reaction (HER) is an effective method for converting intermittent electrical energy into renewable hydrogen energy. However, the high overpotential barrier and sluggish kinetics severely limit the performance of HER. Platinum (Pt), a noble metal, is a highly efficient electrocatalyst and is commonly used in HER to improve the reaction rate, which has an almost zero overpotential. However, the high cost and scarcity of Pt on Earth greatly hinder its large-scale application.

[0003] Over the past few decades, two-dimensional materials such as graphene, transition metal dichalcogenides (TMDs), and MXenes have attracted widespread attention due to their ultrathin layered structures, unique physicochemical properties, and controllable electronic structures. Among these, transition metal dichalcogenides, particularly molybdenum disulfide and diselenides (MoX2, X = S and Se), can be used to design advanced hydrogen evolution electrocatalysts to reduce overpotentials and promote reaction kinetics. Furthermore, transition metal dichalcogenides are competitive candidates due to their excellent catalytic activity, superior stability, abundant terrestrial resources, and relatively low cost. MoSe2 is a typical layered TMD composite material, similar to graphene. In many applications, MoSe2 is often considered an analogue of MoS2, but it exhibits better conductivity, attributed to the metallic nature of selenium atoms. Increasing the number of Se active sites or Se vacancies on the basal plane of MoSe2 is an effective way to improve HER performance, and incorporating heterometallic content into MoSe2 can also enhance HER performance. Phase modulation of molybdenum disulfide / diselenide drives enhanced electrocatalytic performance, and MoSe2-based materials have become a hot research topic in energy storage and conversion due to their excellent stability, ease of processing, and high electrocatalytic reaction (HER) performance. However, current molybdenum selenide materials still suffer from limitations such as poor conductivity and easy aggregation. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an ultradispersed rare earth doped MoSe2 material, its preparation method and application. The ultradispersed rare earth doped MoSe2 material prepared by the present invention exhibits superior catalytic activity in electrocatalytic hydrogen production.

[0005] This invention provides a method for preparing ultradispersed rare earth-doped MoSe2 materials, comprising the following steps:

[0006] S1) Mix solution A and solution B thoroughly to obtain an emulsion;

[0007] Solution A is obtained by mixing a selenium source and hydrazine hydrate; solution B is obtained by mixing a molybdenum source and an aqueous solvent; the aqueous solvent is composed of water and dopamine.

[0008] S2) The rare earth dopant and the emulsion are mixed, ultrasonically dispersed, and then heated to carry out a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain an ultra-dispersed rare earth doped MoSe2 material.

[0009] Preferably, in step S1), the selenium source is selected from at least one of selenium powder, selenomethionine, and dibenzyldiselene;

[0010] The ratio of selenium source to hydrazine hydrate is 70–100 mg: 6–13 mL.

[0011] Preferably, in step S1), the molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, sodium molybdate dihydrate, ammonium phosphomolybdate, molybdenum trioxide, and molybdenum acetate;

[0012] The molybdenum source and aqueous solvent are used in a ratio of 240–250 mg to 35–55 mL.

[0013] The volume ratio of water to dopamine is 30-40:5-15.

[0014] Preferably, in step S1), the mass ratio of the selenium source to the molybdenum source is 70-100:240-250.

[0015] Preferably, in step S2), the rare earth dopant is a metal salt containing rare earth ions; the rare earth ions in the rare earth dopant include Lu. 3+ Tm 3+ Ru 3+ 、Sm 3+ and La 3+ At least one of them.

[0016] Preferably, in step S2), the concentration of the rare earth dopant in the solution obtained by mixing the rare earth dopant and the emulsion is 0.01 to 0.1 mmol / L.

[0017] Preferably, in step S2), the temperature of the solvothermal reaction is 180–220°C and the time is 10–14 h.

[0018] Preferably, in step S2), the volume ratio of hydrogen to argon is 3-7:95-105;

[0019] The annealing temperature is 550–650°C, and the time is 1–3 hours.

[0020] The present invention also provides an ultradispersed rare earth-doped MoSe2 material prepared by the preparation method described above.

[0021] This invention also provides an application of the aforementioned ultradispersed rare earth-doped MoSe2 material as a hydrogen evolution electrocatalyst.

[0022] This invention provides a method for preparing ultradispersed rare-earth-doped MoSe2 materials, comprising the following steps: S1) mixing solution A and solution B to obtain an emulsion; solution A is obtained by mixing a selenium source and hydrazine hydrate; solution B is obtained by mixing a molybdenum source and an aqueous solvent; the aqueous solvent is composed of water and dopamine; S2) mixing a rare-earth dopant with the emulsion, ultrasonically dispersing it uniformly, and then heating it to carry out a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain ultradispersed rare-earth-doped MoSe2 materials. This invention synthesizes ultradispersed rare-earth-doped MoSe2 materials via a solvothermal method. During the solvothermal process, dopamine organic molecules and rare-earth dopant are introduced to regulate the structure of MoSe2. Both dopamine molecules and rare-earth dopant play multiple roles in the synthesis process. Typically, MoSe2 readily aggregates during wet bottom-up synthesis due to its high surface energy. Dopamine molecules carrying functional groups exhibit a strong affinity for Mo atoms and can act as passivating agents, inserting into the Se-Mo-Se interlayer to inhibit excessive growth. Rare earth dopants, with their rare earth cation radii (typically 0.84–1.06 pm) much larger than the Mo ion radius (0.68 pm), easily distort the MoSe2 lattice when they enter the Se-Mo-Se basal plane, leaving Se vacancy defects in the lattice. The resulting ultradispersed rare earth-doped MoSe2 material exhibits excellent catalytic performance in water electrolysis. Attached Figure Description

[0023] Figure 1 This is a SEM image of the ultradispersed rare earth-doped MoSe2 material prepared in Example 1 of the present invention;

[0024] Figure 2 This is a TEM image of the ultradispersed rare earth-doped MoSe2 material prepared in Example 1 of the present invention;

[0025] Figure 3 The image shows the XRD pattern of the ultradispersed rare earth-doped MoSe2 material prepared in Example 1 of this invention.

[0026] Figure 4 This is an electrochemical activity diagram of the ultradispersed rare earth-doped MoSe2 material used as a hydrogen evolution electrocatalyst in Example 1 of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for preparing ultradispersed rare earth-doped MoSe2 materials, comprising the following steps:

[0029] S1) Mix solution A and solution B thoroughly to obtain an emulsion;

[0030] Solution A is obtained by mixing a selenium source and hydrazine hydrate; solution B is obtained by mixing a molybdenum source and an aqueous solvent; the aqueous solvent is composed of water and dopamine.

[0031] S2) The rare earth dopant and the emulsion are mixed, ultrasonically dispersed, and then heated to carry out a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain an ultra-dispersed rare earth doped MoSe2 material.

[0032] In step S1):

[0033] Mix solution A and solution B thoroughly to obtain an emulsion;

[0034] Solution A is obtained by mixing a selenium source (Se source) and hydrazine hydrate (N2H4·H2O); solution B is obtained by mixing a molybdenum source (Mo source) and an aqueous solvent; the aqueous solvent is composed of water and dopamine.

[0035] In some embodiments of the present invention, the selenium source is selected from at least one of selenium powder, selenomethionine, and dibenzyldiselene; preferably, it is selenium powder. The ratio of the selenium source to hydrazine hydrate is 70-100 mg: 6-13 mL, for example, 79 mg: 10 mL.

[0036] In some embodiments of the present invention, the molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, sodium molybdate dihydrate (Na2MoO4·2H2O), ammonium phosphomolybdate, molybdenum trioxide, and molybdenum acetate; preferably sodium molybdate. The volume ratio of water to dopamine is 30-40:5-15, for example, 35:10. The volume ratio of the molybdenum source to the aqueous solvent is 240-250 mg:35-55 mL, for example, 242 mg:45 mL.

[0037] In some embodiments of the present invention, the mass ratio of the selenium source to the molybdenum source is 70-100:240-250, for example 79:242.

[0038] In step S2):

[0039] The rare earth dopant and the emulsion are mixed and ultrasonically dispersed. The mixture is then heated to carry out a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain a super-dispersed rare earth doped MoSe2 material.

[0040] In some embodiments of the present invention, the rare earth dopant is a metal salt containing rare earth ions; preferably, the rare earth ions in the rare earth dopant include Lu. 3+ Tm 3+ Ru 3+ 、Sm 3+ and La 3+ At least one of the following. Specifically, the rare earth dopant is a ruthenium salt, such as Ru(NO3)3·2H2O, La(NO3)3·2H2O, Sm(NO3)3·2H2O, Lu(NO3)3·2H2O or Tm(NO3)3·2H2O.

[0041] In some embodiments of the present invention, the concentration of the rare earth dopant in the solution obtained by mixing the rare earth dopant and the emulsion is 0.01 to 0.1 mmol / L, for example, 0.05 mmol / L.

[0042] In some embodiments of the present invention, the temperature of the solvothermal reaction is 180–220°C, for example, 200°C, and the time is 10–14 hours, for example, 12 hours. The solvothermal reaction is carried out in an autoclave. The process after the solvothermal reaction includes: cooling, filtration, washing, and drying. The cooling is natural cooling to room temperature. The filtered solid product is washed. The washing agent used is deionized water and ethanol. The drying is vacuum drying at a temperature of 100–140°C, for example, 120°C.

[0043] In some embodiments of the present invention, the volume ratio of hydrogen to argon is 3-7:95-105, for example 5:100.

[0044] In some embodiments of the present invention, the annealing temperature is 550-650°C, for example 600°C, and the time is 1-3 hours, for example 2 hours.

[0045] The present invention also provides an ultradispersed rare earth-doped MoSe2 material prepared by the preparation method described above.

[0046] This invention also provides an application of the above-described ultradispersed rare earth-doped MoSe2 material as a hydrogen evolution electrocatalyst (catalyst for electrochemical hydrogen evolution reaction (HER)).

[0047] This invention significantly enhances the HER activity of MoSe2 materials by controlling the synthesis of precursors and doping them with various rare earth elements.

[0048] The preparation process provided by this invention is simple, environmentally friendly, inexpensive, and has low production costs, which is conducive to large-scale market promotion.

[0049] This invention uses a series of rare earth elements for doping to form a control, in an attempt to find the optimal electrocatalytic activity. It can be seen that the corresponding electrocatalytic activities are significantly improved, proving that our doping is very effective.

[0050] In this invention, dopamine molecules carrying functional groups exhibit a strong affinity for Mo atoms and can be used as passivating agents to insert into the Se-Mo-Se interlayer, inhibiting its excessive growth. The rare earth cation radius of the rare earth dopant (typically 0.84–1.06 pm) is much larger than that of the Mo ion (0.68 pm). When it enters the Se-Mo-Se basal plane, it easily causes lattice distortion of MoSe2 and leaves Se vacancy defects in the lattice.

[0051] The ultradispersed rare-earth-doped MoSe2 material obtained by this invention has a large specific surface area, which can be 180-190 m². 2 g -1 It has many active sites, containing 14% to 15% Se vacancy defects, good cycle stability, simple process, low production cost, low environmental pollution, and its activity is greatly improved after doping with a series of rare earth metals.

[0052] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0053] To further illustrate the present invention, the following detailed description of an ultradispersed rare earth-doped MoSe2 material, its preparation method and application are provided in conjunction with embodiments, but should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] The preparation of Ru-MoSe2 includes the following steps:

[0056] (1) Dissolve 79 mg of Se source (selenium powder) in 10 mL of hydrazine hydrate to obtain solution A;

[0057] 242 mg of Mo source (Na2MoO4·2H2O) was dissolved in 45 mL of aqueous solvent (water and dopamine, volume ratio 35:10) to obtain solution B;

[0058] Mix solution A and solution B thoroughly to obtain an emulsion;

[0059] (2) A rare earth dopant (Ru(NO3)3·2H2O) was added to the emulsion and ultrasonically dispersed. The emulsion was then transferred to an autoclave and heated to 200°C for a solvothermal reaction for 12 hours. After the autoclave cooled naturally to room temperature, the filtered solid product was washed with deionized water and ethanol and dried in a vacuum drying oven at 120°C. The dried material was annealed at 600°C for 2 hours in a mixture of hydrogen and argon (volume ratio of hydrogen to argon: 5:100) to obtain a superdispersed rare earth doped MoSe2 material (Ru-MoSe2).

[0060] Figure 1 This is a SEM image of the ultradispersed rare-earth-doped MoSe2 material prepared in Example 1 of this invention. From... Figure 1 It is known that the ultra-dispersed rare earth-doped MoSe2 material is a 3D nanolayer structure, with the doped rare earth elements uniformly dispersed on the material surface.

[0061] Figure 2 This is a TEM image of the ultradispersed rare-earth-doped MoSe2 material prepared in Example 1 of this invention. Figure 2 It can be seen that the ultra-dispersed rare earth-doped MoSe2 material has good dispersion.

[0062] Figure 3 This is the XRD pattern of the ultradispersed rare-earth-doped MoSe2 material prepared in Example 1 of this invention. Figure 3 It can be seen that doping did not change the corresponding peaks of the raw materials.

[0063] The specific method for electrochemical performance testing is as follows: using a Chenhua 660e electrochemical workstation, a three-electrode system is adopted, with a graphite rod as the counter electrode and a Hg / HgO reference electrode as the reference electrode; the electrolyte is a 1 mol / L KOH aqueous solution.

[0064] 5 mg of sample (ultra-dispersed rare earth-doped MoSe2 material) was dissolved in 375 mL of water and 120 μL of ethanol, followed by the addition of 5 μL of Nafion solution. After sonication for 1 h, 25 μL was dropped onto a 0.025 cm² plate. 2 The sample was placed on hydrophilic carbon paper and allowed to air dry naturally. Cyclic voltammetry was used (scan potential from -0.8V to -1.8V, scan rate 0.2Vs). -1 The material was activated, and then its performance was tested using linear voltammetry (LSV) (scan potential from -0.8V to -1.8V, scan rate of 0.005Vs). -1 The overpotential value and the polarization curve of the catalyst in the electrolyte (KOH aqueous solution) were obtained. Figure 4 This is an electrochemical activity diagram of the ultradispersed rare earth-doped MoSe2 material used as a hydrogen evolution electrocatalyst in Example 1 of the present invention.

[0065] from Figure 4 It can be seen that applying the ultra-dispersed rare-earth-doped MoSe2 material of Example 1 to electrocatalyzed hydrogen production via HER can significantly improve its overpotential, reaching -10 A / cm under alkaline conditions. 2 The voltage reached 214 mV, which is a significant improvement compared to pure MoSe2 material (397 mV).

[0066] Example 2

[0067] The difference from Example 1 is as follows:

[0068] In step (2), the rare earth dopant is replaced with La(NO3)3·2H2O, and the remaining steps are the same as in Example 1, to obtain ultra-dispersed rare earth doped MoSe2 material (La-MoSe2).

[0069] The electrochemical activity of the ultradispersed rare-earth-doped MoSe2 material as a hydrogen evolution electrocatalyst was studied according to the method in Example 1, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the overpotential of La-MoSe2 material is -10 A / cm under alkaline conditions. 2 It reached 338mv.

[0070] Example 3

[0071] The difference from Example 1 is as follows:

[0072] In step (2), the rare earth dopant is replaced with Sm(NO3)3·2H2O, and the remaining steps are the same as in Example 1, to obtain ultra-dispersed rare earth doped MoSe2 material (Sm-MoSe2).

[0073] The electrochemical activity of the ultradispersed rare-earth-doped MoSe2 material as a hydrogen evolution electrocatalyst was studied according to the method in Example 1, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the overpotential of Sm-MoSe2 material is -10 A / cm under alkaline conditions. 2 It reached 273mv.

[0074] Example 4

[0075] The difference from Example 1 is as follows:

[0076] In step (2), the rare earth dopant is replaced with Lu(NO3)3·2H2O, and the remaining steps are the same as in Example 1, to obtain ultra-dispersed rare earth doped MoSe2 material (Lu-MoSe2).

[0077] The electrochemical activity of the ultradispersed rare-earth-doped MoSe2 material as a hydrogen evolution electrocatalyst was studied according to the method in Example 1, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the overpotential of Lu-MoSe2 material is -10 A / cm under alkaline conditions. 2 It reached 233mv.

[0078] Example 5

[0079] The difference from Example 1 is as follows:

[0080] In step (2), the rare earth dopant is replaced with Tm(NO3)3·2H2O, and the remaining steps are the same as in Example 1, to obtain ultra-dispersed rare earth doped MoSe2 material (Tm-MoSe2).

[0081] The electrochemical activity of the ultradispersed rare-earth-doped MoSe2 material as a hydrogen evolution electrocatalyst was studied according to the method in Example 1, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the overpotential of Tm-MoSe2 material is -10 A / cm under alkaline conditions. 2 The value reached 329 mV. For pure MoSe2, the electrocatalytic activity of HER was improved by doping with different rare earth elements, with ruthenium doping showing the best effect and good stability.

[0082] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing ultradispersed rare earth-doped MoSe2 material, comprising the following steps: S1) Mix solution A and solution B thoroughly to obtain an emulsion; Solution A is obtained by mixing a selenium source and hydrazine hydrate; solution B is obtained by mixing a molybdenum source and an aqueous solvent; the aqueous solvent is composed of water and dopamine. S2) The dopant and the emulsion are mixed, ultrasonically dispersed, and then heated to carry out a solvothermal reaction. The resulting solid product is annealed in a mixture of hydrogen and argon to obtain ultra-dispersed rare earth doped MoSe2 material. The dopant is a metal salt containing rare earth ions and / or containing Ru. 3+ Metal salts; the rare earth ions include Lu 3+ Tm 3+ 、Sm 3+ and La 3+ At least one of them.

2. The preparation method according to claim 1, characterized in that, In step S1), the selenium source is selected from at least one of selenium powder, selenomethionine, and dibenzyldiselene; The ratio of selenium source to hydrazine hydrate is 70-100 mg: 6-13 mL.

3. The preparation method according to claim 1, characterized in that, In step S1), the molybdenum source is selected from at least one of ammonium molybdate, sodium molybdate, sodium molybdate dihydrate, ammonium phosphomolybdate, molybdenum trioxide, and molybdenum acetate; The molybdenum source and aqueous solvent are used in a ratio of 240-250 mg to 35-55 mL. The volume ratio of water to dopamine is 30~40:5~15.

4. The preparation method according to claim 1, characterized in that, In step S1), the mass ratio of the selenium source to the molybdenum source is 70~100:240~250.

5. The preparation method according to claim 1, characterized in that, In step S2), the concentration of the dopant in the solution obtained by mixing the dopant and the emulsion is 0.01~0.1 mmol / L.

6. The preparation method according to claim 1, characterized in that, In step S2), the temperature of the solvothermal reaction is 180~220℃ and the time is 10~14 h.

7. The preparation method according to claim 1, characterized in that, In step S2), the volume ratio of hydrogen to argon is 3~7:95~105; The annealing temperature is 550~650℃, and the time is 1~3 h.

8. The ultradispersed rare earth-doped MoSe2 material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the ultradispersed rare earth-doped MoSe2 material as a hydrogen evolution electrocatalyst according to claim 8.

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