Two-dimensional molybdenum-based nanosheet catalyst and preparation method and application thereof
The preparation of two-dimensional molybdenum-based nanosheet catalysts through hydrothermal reaction and heat treatment, changing their surface oxidation environment and forming acidic sites, solving the problem of limited active sites of two-dimensional molybdenum sulfide nanosheets and significantly improving their alkaline electrolytic water Catalytic properties in hydrogen evolution.
Patent Information
- Application Number
- CN202411160053.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2025-01-03
Smart Images
Figure CN119243226A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of new energy materials, and specifically relates to a two-dimensional molybdenum-based nanosheet catalyst and a preparation method and application thereof. Background Art
[0002] As a green energy with high enthalpy energy density and zero carbon emissions, hydrogen energy can significantly reduce the use of fossil energy and will play an important role in the construction of a green energy society in the future. Hydrogen evolution (HER) driven by water electrolysis using renewable energy (hydropower, wind power, solar power, etc.) is considered to be the most economical and effective way to produce hydrogen. Producing hydrogen through HER usually requires the use of precious metal platinum-based catalysts to reduce the overpotential of hydrogen production, but the small reserves and high prices of precious metals limit their large-scale application in the HER field.
[0003] Two-dimensional transition metal dichalcogenides (TMDs) are rich in rare earth elements, especially MoS2, which has relatively low cost and excellent catalytic performance. When MoS2 nanosheets are used as electrocatalysts, their 2D layered structure gives them a large specific surface area and abundant active sites for hydrogen evolution reactions. In addition, the in-plane resistivity of 2D transition metal sulfide nanosheets is smaller than the basal resistivity, which is conducive to the transmission of electrons and thus improves the electrical conductivity. By optimizing the preparation process and regulating the material structure, the electrocatalytic performance of MoS2 nanosheets can be further improved to achieve more efficient energy conversion and storage; however, the number of active sites and inert basal planes of MoS2 is limited, which also greatly limits its catalytic activity in HER. Summary of the invention
[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the main purpose of the present invention is to provide a two-dimensional molybdenum-based nanosheet catalyst and a preparation method thereof, aiming to solve the problem of poor electrocatalytic activity of molybdenum sulfide nanosheets caused by the limited number of active sites and inert basal planes of existing molybdenum sulfide nanosheets.
[0005] The main purpose of the present invention is to provide the application of the surface acidic two-dimensional nanocatalyst in hydrogen evolution by alkaline water electrolysis.
[0006] The objective of the present invention is achieved through the following technical solutions:
[0007] A method for preparing a two-dimensional molybdenum-based nanosheet catalyst comprises the following steps:
[0008] 1) dissolving a metal molybdenum source in a solvent, and then stirring and mixing with a sulfide to obtain a mixed solution;
[0009] 2) adding an alkali / alkaline earth metal to the mixed solution in step 1) to carry out a hydrothermal reaction to obtain an intermediate product;
[0010] 3) heat-treating the intermediate product in step 2) to obtain a two-dimensional molybdenum-based nanosheet catalyst.
[0011] In certain specific embodiments, the solvent in step 1) is any one of ethanol, deionized water, or a mixture thereof; the mass ratio of the metal molybdenum source to the sulfide is (1-2):(2-4); the mass ratio of the alkali / alkaline earth metal to the sulfide is (1-2):(20-40).
[0012] In certain specific embodiments, the conditions of the hydrothermal reaction in step 2) are: heating to 180-220° C. at a heating rate of 5-10° C. / min and maintaining the reaction for 12-24 h.
[0013] In some specific embodiments, the product after the hydrothermal reaction is further subjected to washing, separation and drying treatments.
[0014] In certain specific embodiments, the metal molybdenum source in step 1) includes one or more of molybdenum pentachloride, molybdenum chloride, ammonium molybdate, and sodium molybdate.
[0015] In certain specific embodiments, the sulfide in step 1) includes, but is not limited to, one or more of thiourea, propylthiourea, benzylthiourea, cyclohexylthiourea, and N-ethylthiourea.
[0016] In certain specific embodiments, the alkali / alkaline earth metal in step 2) includes one or more of lithium chloride, sodium chloride, potassium chloride, calcium chloride, barium chloride, strontium chloride, magnesium chloride, and aluminum chloride.
[0017] In certain specific embodiments, the heat treatment conditions in step 3) are: in an air atmosphere or an oxygen atmosphere, the temperature is increased to 150-350° C. at a heating rate of 2-5° C. / min and the reaction is maintained for 0.5-2 h.
[0018] A two-dimensional molybdenum-based nanosheet catalyst prepared by the aforementioned preparation method.
[0019] The application of the aforementioned two-dimensional molybdenum-based nanosheet catalyst in the field of catalysis.
[0020] Compared with the prior art, the present invention has at least the following advantages:
[0021] The present invention provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises preparing an alkali / alkaline earth metal-molybdenum sulfide by a hydrothermal reaction, and then changing the surface oxidation environment of the alkali / alkaline earth metal-molybdenum sulfide by heat treatment; due to the change of the surface oxidation environment structure, an "alkali / alkaline earth metal-oxygen-molybdenum sulfide" structure with an acidic site is formed, and the acidic site can be used as an active site for a hydrogen evolution reaction, thereby enhancing the hydrogen evolution performance under an alkaline medium; the two-dimensional molybdenum-based nanosheet catalyst is used for a high-performance water electrolysis hydrogen evolution electrolysis reaction, and the acidic site on its surface can be used as an active site for a hydrogen evolution reaction, thereby enhancing the hydrogen evolution performance under an alkaline medium. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the specific embodiments or the description of the prior art will be briefly introduced below.
[0023] Figure 1 is the XRD pattern of the intermediate product in Example 1 of the present invention;
[0024] Figure 2 This is a SEM image of the two-dimensional molybdenum-based nanosheet catalyst in Example 1 of the present invention;
[0025] Figure 3 This is a scanning linear voltammetry curve of the two-dimensional molybdenum-based nanosheet catalyst in Example 1 of the present invention;
[0026] Figure 4 This is a process flow chart of the two-dimensional molybdenum-based nanosheet catalyst provided by the present invention. DETAILED DESCRIPTION
[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.
[0028] When a certain amount, concentration or other value or parameter is expressed in the form of a range, a preferred range, or a preferred upper and lower numerical limit, it should be understood that it is equivalent to specifically revealing any range by combining any pair of upper range limits or preferred numerical values with any lower range limit or preferred numerical value, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical range values listed herein include the endpoints of the range, and all integers and fractions within the range.
[0029] Unless otherwise indicated, all percentages, parts, ratios, etc. herein are by weight.
[0030] The materials, methods, and examples herein are illustrative and are not to be construed as limiting unless specifically stated.
[0031] Example 1
[0032] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, and its process flow is as follows: Figure 4 As shown, the specific steps include:
[0033] 1) Weigh 0.2 g of ammonium molybdate and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.4 g of thiourea, and stir at room temperature at a rate of 500 rpm for 0.5 h to obtain a mixed solution;
[0034] 2) Add 0.01 g of lithium chloride to the mixed solution, stir at a rate of 500 rpm for 0.5 h, then transfer it to a 100 mL Teflon reactor liner, put on a stainless steel jacket, transfer it to a hydrothermal oven, raise the temperature to 200 ° C at a rate of 5 ° C / min for hydrothermal reaction for 22 h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60 ° C for 10 h to obtain the intermediate product Li-MoS2;
[0035] 3) The obtained intermediate product Li-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 200 sccm, and the temperature was raised to 300°C at a heating rate of 5°C / min and kept at this condition for 1 hour. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet LiO-MoS with surface acidity regulation was collected. 2-x Catalysts for characterization of morphology, phase and performance.
[0036] Example 2
[0037] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0038] 1) Weigh 0.1 g of sodium molybdate and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.3 g of propylthiourea, and stir at room temperature at a rate of 600 rpm for 0.5 h to obtain a mixed solution;
[0039] 2) Add 0.01 g of sodium chloride to the mixture, stir at 400 rpm for 0.5 h, transfer it to a 100 mL Teflon reactor liner, put on a stainless steel jacket, transfer it to a hydrothermal oven, heat it to 220 ° C at a rate of 10 ° C / min for 24 h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction, and transfer it to a vacuum oven and dry it at 60 ° C for 10 h to obtain the intermediate product Na-MoS2;
[0040] 3) The obtained intermediate product Na-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then oxygen atmosphere was introduced at a rate of 200 sccm, and the temperature was raised to 350°C at a rate of 2°C / min and kept at this condition for 2h. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet NaO-MoS with surface acidity regulation was collected. 2-x Catalysts for characterization of morphology, phase and performance.
[0041] Example 3
[0042] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0043] 1) Weigh 0.2 g of molybdenum pentachloride and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.6 g of benzylthiourea, and stir at room temperature at a rate of 400 rpm for 0.5 h to obtain a mixed solution;
[0044] 2) Add 0.02g aluminum chloride to the mixed solution, stir at 400rpm for 0.5h, transfer it to a 100mL Teflon reactor liner, put on a stainless steel jacket, transfer it to a hydrothermal oven, heat it to 220℃ at a rate of 5℃ / min for 18h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60℃ for 10h to obtain the intermediate product Mg-MoS2;
[0045] 3) The obtained intermediate product Mg-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 100 sccm, and the temperature was increased to 250°C at a heating rate of 3°C / min and kept at this condition for 2h. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet MgO-MoS2 with surface acidity regulation was collected. 2-x Catalysts for characterization of morphology, phase and performance.
[0046] Example 4
[0047] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0048] 1) Weigh 0.2 g of molybdenum chloride and dissolve it in 50 ml of alcohol, stir until it is completely dissolved, then add 0.4 g of thiourea, and stir at room temperature at a rate of 600 rpm for 0.5 h to obtain a mixed solution;
[0049] 2) Add 0.01 g of lithium chloride to the mixed solution, stir at a rate of 600 rpm for 0.5 h, then transfer it to a 100 mL Teflon reactor liner, put on a stainless steel jacket, transfer it to a hydrothermal oven, raise the temperature to 200 ° C at a rate of 5 ° C / min for hydrothermal reaction for 24 h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60 ° C for 10 h to obtain the intermediate product Al-MoS2;
[0050] 3) The obtained intermediate product Al-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 300 sccm, and the temperature was raised to 350°C at a heating rate of 10°C / min and kept at this condition for 1 hour. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet AlO-MoS with surface acidity regulation was collected. 2-x Catalysts for characterization of morphology, phase and performance.
[0051] Example 5
[0052] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0053] 1) Weigh 0.2 g of ammonium molybdate and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.4 g of cyclohexylthiourea, and stir at room temperature at a rate of 200 rpm for 0.5 h to obtain a mixed solution;
[0054] 2) Add 0.01g calcium chloride to the mixed solution, stir at a rate of 200rpm for 0.5h, then transfer it to a 100mL Teflon-lined reactor, put on a stainless steel jacket, transfer it to a hydrothermal oven, heat it to 180℃ at a rate of 10℃ / min for 18h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60℃ for 10h to obtain the intermediate product Ca-MoS2;
[0055] 3) The obtained intermediate product Ca-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 200 sccm, and the temperature was raised to 300°C at a heating rate of 5°C / min and kept at this condition for 1 hour. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet CaO-MoS with surface acidity adjustment was collected. 2-x Catalysts for characterization of morphology, phase and performance.
[0056] Example 6
[0057] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0058] 1) Weigh 0.2 g of ammonium molybdate and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.6 g of N-ethylthiourea, and stir at room temperature at a rate of 500 rpm for 0.5 h to obtain a mixed solution;
[0059] 2) Add 0.02 g of strontium chloride to the mixed solution, stir at a rate of 500 rpm for 0.5 h, then transfer it to a 100 mL Teflon reactor liner, put on a stainless steel jacket, transfer it to a hydrothermal oven, heat it to 220° C. at a rate of 5° C. / min for hydrothermal reaction for 12 h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60° C. for 10 h to obtain the intermediate product Sr-MoS2;
[0060] 3) The obtained intermediate product Sr-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 200 sccm, and the temperature was increased to 250°C at a heating rate of 5°C / min and kept at this condition for 2h. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet SrO-MoS with surface acidity regulation was collected. 2-x Catalysts for morphology, phase and performance characterization.
[0061] Example 7
[0062] This embodiment provides a method for preparing a two-dimensional molybdenum-based nanosheet catalyst, which comprises the following steps:
[0063] 1) Weigh 0.2 g of ammonium molybdate and dissolve it in 50 ml of deionized water, stir until it is completely dissolved, then add 0.4 g of thiourea, and stir at room temperature at a rate of 400 rpm for 0.5 h to obtain a mixed solution;
[0064] 2) Add 0.01 g of barium chloride to the mixed solution, stir at a rate of 400 rpm for 0.5 h, then transfer it to a 100 mL Teflon-lined reactor, put on a stainless steel jacket, transfer it to a hydrothermal oven, heat it to 220° C. at a rate of 5° C. / min for 14 h, and after the reaction is completed, cool it to room temperature; wash it with deionized water, collect the filtered product by suction filtration, and transfer it to a vacuum oven and dry it at 60° C. for 10 h to obtain the intermediate product Ba-MoS2;
[0065] 3) The obtained intermediate product Ba-MoS2 was placed in an alumina ceramic boat; and then transferred to a tube furnace, and then an oxygen atmosphere was introduced at a rate of 200 sccm, and the temperature was raised to 350°C at a heating rate of 5°C / min and kept at this condition for 0.5h. After the heat treatment was completed and the temperature dropped to room temperature, the two-dimensional nanosheet BaO-MoS with surface acidity regulation was collected. 2-x Catalysts for morphology, phase and performance characterization.
[0066] Performance Test:
[0067] 1) Appearance and organization test
[0068] This application takes Example 1 as an example to describe the intermediate product in the preparation method of this application, the prepared two-dimensional molybdenum-based nanosheet catalyst (AO-MoS 2-x ) The morphology and phase of the samples were characterized by using a field emission scanning electron microscope from Zeiss, Germany, and a high-resolution powder X-ray diffractometer from Spectris, UK. Figure 1-Figure 2 As shown, Figure 1 Two-dimensional Mo-based nanosheet catalyst (AO-MoS 2-x )’s XRD pattern, from Figure 1 It can be seen that the two-dimensional molybdenum-based nanosheet catalyst (AO-MoS 2-x ), whose substrate is MoS2 (JCPDS No: 37-1492; Figure 2 Two-dimensional Mo-based nanosheet catalyst (AO-MoS 2-x ) of the SEM spectrum, from Figure 2 It can be seen that the catalyst has a two-dimensional nanosheet morphology.
[0069] 2) Electrochemical performance
[0070] The two-dimensional molybdenum-based nanosheet catalyst provided by the present invention is applied to hydrogen evolution in alkaline water electrolysis. This application takes the two-dimensional molybdenum-based nanosheet catalyst prepared in Example 1 as an example, and tests the electrochemical performance of the two-dimensional molybdenum-based nanosheet catalyst in hydrogen evolution in water electrolysis, specifically:
[0071] The electrochemical tests were all conducted at room temperature using a CHI760E electrochemical workstation. The catalyst preparation method is as follows: 10 mg of sample (two-dimensional molybdenum-based nanosheet catalyst) was dispersed in a mixed solution of 870 μL of anhydrous ethanol, 100 μL of deionized water, and 30 μL of Nafion. The solution was ultrasonicated in an ultrasonic cleaner to become a uniform ink-like state. Then, 20 μL of the solution was dropped on the surface of the glassy carbon electrode using a pipette and dried. 1M KOH (pH = 14) solution was used as an alkaline electrolyte for testing. A three-electrode system was used in the test, using a carbon rod as the counter electrode and Ag / AgCl as the reference electrode. The sample to be tested was titrated on the surface of the glassy carbon electrode (3 mm in diameter), and a scanning linear voltammetric curve test was performed with a scanning speed of 0.1 mV and a potential range of (-0.9 to -1.8). The measured data was calibrated with a reversible hydrogen electrode (RHE) according to the equation:
[0072] E RHE =E Ag / AgCl +1.02V
[0073] Test results such as Figure 3 As shown, Figure 3 The linear voltammetry curve of the two-dimensional molybdenum-based nanosheet catalyst is shown in Figure 2. It can be concluded that the pure phase MoS2 catalyst drives 10 mA / cm 2 The potential of 598 mV is required, and the two-dimensional molybdenum-based nanosheet catalyst (AO-MoS 2-x ) Only 210mV overpotential is needed to generate 10mA / cm 2 The current density is improved significantly, and the regulation effect is excellent.
[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.
Claims
1. A method for preparing a two-dimensional molybdenum-based nanosheet catalyst, characterized in that: The steps include: 1) dissolving a metal molybdenum source in a solvent, and then stirring and mixing with a sulfide to obtain a mixed solution; 2) adding an alkali / alkaline earth metal to the mixed solution in step 1) to carry out a hydrothermal reaction to obtain an intermediate product; 3) heat-treating the intermediate product in step 2) to obtain a two-dimensional molybdenum-based nanosheet catalyst.
2. The method for preparing the surface acidic two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: In step 1), the solvent is any one of ethanol, deionized water, or a mixture thereof; the mass ratio of the metal molybdenum source to the sulfide is (1-2):(2-4); the mass ratio of the alkali / alkaline earth metal to the sulfide is (1-2):(20-40).
3. The method for preparing the two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: The conditions of the hydrothermal reaction in step 2) are: heating to 180-220°C at a heating rate of 5-10°C / min and maintaining the reaction for 12-24h.
4. The method for preparing the two-dimensional molybdenum-based nanosheet catalyst according to claim 3, characterized in that: The method also includes washing, separating and drying the product after the hydrothermal reaction.
5. The method for preparing the two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: The metal molybdenum source in step 1) includes one or more of molybdenum pentachloride, molybdenum chloride, ammonium molybdate, and sodium molybdate.
6. The method for preparing the two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: The sulfide in step 1) includes, but is not limited to, one or more of thiourea, propylthiourea, benzylthiourea, cyclohexylthiourea, and N-ethylthiourea.
7. The method for preparing the two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: The alkali / alkaline earth metal in step 2) includes one or more of lithium chloride, sodium chloride, potassium chloride, calcium chloride, barium chloride, strontium chloride, magnesium chloride, and aluminum chloride.
8. The method for preparing a two-dimensional molybdenum-based nanosheet catalyst according to claim 1, characterized in that: The heat treatment conditions in step 3) are: in an air atmosphere or an oxygen atmosphere, the temperature is raised to 150-350° C. at a heating rate of 2-5° C. / min and the reaction is maintained for 0.5-2 h.
9. A two-dimensional molybdenum-based nanosheet catalyst prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the two-dimensional molybdenum-based nanosheet catalyst according to claim 9 in the field of catalysis.