Variable composition Mo-Ni alloy regulated by ethanol solvent, preparation method and application thereof

Abstract

The application discloses an ethanol solvent-regulated variable-component Mo-Ni alloy, a preparation method and application thereof, and the method comprises the following steps: S1, dissolving a nickel salt, a molybdenum salt and urea in a mixed solvent of ethanol and ultrapure water according to a certain stoichiometric ratio, and stirring to form a uniform mixed solution at room temperature; S2, placing the mixed solution prepared in the step S1 in a constant-temperature device and performing heating treatment; S3, after the reaction in the step S2 is completed and the solution temperature is reduced to room temperature, repeatedly washing the reaction product by using ultrapure water and ethanol solvent alternately, and collecting a precipitate; S4, drying the precipitate collected in the step S3, and the obtained dried product is a variable-component Mo-Ni precursor material; and S5, performing heat treatment on the variable-component Mo-Ni precursor material in the step S4 in a H2 / Ar mixed atmosphere, so that a variable-component Mo-Ni alloy material with a three-dimensional nano hierarchical structure is obtained, and the problems of high hydrogen evolution potential and complicated preparation process in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis, specifically to a variable-component Mo-Ni alloy controlled by ethanol solvent, its preparation method, and its application. Background Technology

[0002] Hydrogen energy is a green, clean, and zero-carbon emission secondary energy source with broad application prospects. Promoting the rapid and efficient development of hydrogen energy is one of the important ways to drive the transformation and upgrading of the energy structure and build a new energy system. Therefore, achieving the effective conversion from renewable energy to hydrogen energy based on the key technology of electrocatalytic water splitting has become a current research hotspot.

[0003] To improve the efficiency of hydrogen production in water electrolysis, highly active hydrogen evolution catalysts are indispensable core participants in the reaction. Currently, platinum (Pt), a noble metal, is the most active catalyst material in the hydrogen evolution reaction. However, the low storage capacity and high cost of Pt increase the cost of industrial applications. To avoid this disadvantage, non-noble metal-based hydrogen evolution catalysts have emerged, especially transition metal-based materials represented by Ni and Mo. Studies have found that the strong synergistic effect of Mo-Ni alloys gives them an electronic structure similar to that of noble metal Pt. However, in practical experimental studies, the hydrogen evolution activity of Mo-Ni alloys still needs further optimization and improvement. Xu JL et al., in the paper "Powder metallurgysynthesis of porous NiMo alloys as efficient electrocatalysts to enhance the hydrogen evolution reaction[J].Journal of Alloys and Compounds,2021,865:158901.", used powder metallurgy to analyze various alloy catalysts with different Mo:Ni ratios, but this method is relatively cumbersome. Summary of the Invention

[0004] This invention provides a variable-component Mo-Ni alloy controlled by ethanol solvent, its preparation method, and its application, which solves the problems of high hydrogen evolution potential and cumbersome preparation process in the prior art.

[0005] To solve this technical problem, the present invention provides the following technical solution:

[0006] A method for preparing a variable-composition Mo-Ni alloy controlled by ethanol solvent includes the following steps:

[0007] S1. Dissolve nickel salt, molybdenum salt, and urea in a mixed solvent of ethanol and ultrapure water in a certain stoichiometric ratio, and stir at room temperature to form a homogeneous mixed solution.

[0008] S2. Place the mixed solution prepared in step S1 in a constant temperature device and heat it.

[0009] S3. After the reaction in step S2 is completed and the solution temperature is reduced to room temperature, the reaction product is washed repeatedly with ultrapure water and ethanol solvent, and the precipitate is collected.

[0010] S4. The precipitate collected in step S3 is dried, and the resulting dried product is a variable component Mo-Ni precursor material.

[0011] S5. Heat-treat the variable composition Mo-Ni precursor material from step S4 in an H2 / Ar mixed atmosphere to obtain a variable composition Mo-Ni alloy material with a three-dimensional nano-hierarchical structure.

[0012] A variable-component Mo-Ni alloy alkaline hydrogen evolution catalyst was prepared using nickel salts, molybdenum salts, urea, and ethanol solvent as raw materials through hydrothermal reaction and high-temperature heat treatment. The catalyst's three-dimensional structure increases the exposed area of ​​the catalyst material, which is beneficial for increasing the number of reactive sites.

[0013] Preferably, in step S1, the nickel salt is selected from any one of nickel chloride, nickel nitrate, or nickel sulfate; and the molybdenum salt is selected from sodium molybdate or ammonium molybdate.

[0014] Preferably, the molar ratio of nickel salt, molybdenum salt, and urea is 1:0.12-0.15:10-15.

[0015] Due to the different dominant roles of Mo and Ni metals in the hydrogen evolution reaction, adjusting the composition of the two metals can further improve the Gibbs free energy of the intermediate product, thereby enhancing the catalytic performance of the hydrogen evolution catalyst and making it exhibit lower overpotential and faster hydrogen evolution reaction kinetics.

[0016] Preferably, the volume ratio of ethanol to water in the mixed solvent is 2:1.

[0017] Preferably, the amount of the mixed solvent used is 36 mL of mixed solvent per millimole of nickel salt.

[0018] Compositional regulation caused by ethanol solvent is the main factor in improving the hydrogen evolution catalytic activity of Mo-Ni alloy in alkaline solution. By controlling the content of ethanol in the second phase solvent, a variable composition Mo-Ni alloy alkaline hydrogen evolution catalyst can be prepared.

[0019] Preferably, the reaction temperature in step S2 is 120–180°C, and the reaction time is 4–10 h.

[0020] Preferably, step S3 involves collecting the precipitated reactants by centrifugation.

[0021] Preferably, the drying process in step S4 can be low-temperature freeze drying or vacuum drying.

[0022] Preferably, the heat treatment temperature in step S5 is 500–650°C.

[0023] A variable-component Mo-Ni alloy alkaline hydrogen evolution catalyst was prepared by controlling the high-temperature heat treatment temperature.

[0024] This solution provides a variable composition Mo-Ni alloy controlled by ethanol solvent, which is prepared using the above-described method.

[0025] This solution provides the application of the aforementioned ethanol solvent-controlled variable component Mo-Ni alloy in alkaline water electrolysis for hydrogen evolution, wherein the ethanol solvent-controlled variable component Mo-Ni alloy serves as a cathode hydrogen evolution catalyst.

[0026] The Mo-Ni alloy in this scheme, used as a cathode hydrogen evolution catalyst, exhibits a hydrogen evolution potential as low as 44.76 mV, a relatively fast kinetic rate, and good stability.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] A variable-component Mo-Ni alloy alkaline hydrogen evolution catalyst was prepared using nickel salt, molybdenum salt, urea, and ethanol solvent as raw materials through hydrothermal reaction and high-temperature heat treatment. The ethanol content (0–36 mL) of the second-phase solvent and the high-temperature heat treatment temperature (500–650 °C) were controlled. The three-dimensional structure increases the exposed area of ​​the catalyst material, which is beneficial for increasing the number of reactive sites. Furthermore, due to the different dominant roles of Mo and Ni metals in the hydrogen evolution reaction, adjusting the composition of the two metals can further improve the Gibbs free energy of the intermediate products, thereby enhancing the catalytic performance of the hydrogen evolution catalyst, resulting in a lower overpotential and faster hydrogen evolution reaction kinetics. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a flowchart illustrating the preparation of a variable-component Mo-Ni alloy controlled by ethanol solvent, as described in Example 1 of the present invention.

[0031] Figure 2To prepare a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention 2.24 X-ray diffraction pattern of the alloy;

[0032] Figure 3 To prepare a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention 2.24 Scanning electron microscope images of the alloy;

[0033] Figure 4 (a) shows the preparation of a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention. 2.24 Transmission electron microscope image of the alloy. Figure 4 (b) shows the preparation of a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention. 2.24 Energy dispersive X-ray spectral elemental diagram of the alloy;

[0034] Figure 5 To prepare a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention 2.24 Linear voltammetric curves of the alloy (used as an alkaline hydrogen evolution catalyst and Pt / C catalyst) in 1M KOH;

[0035] Figure 6 To prepare a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention 2.24 Tafel slope diagram of Pt / C catalyst used as alkaline hydrogen evolution catalyst in 1M KOH;

[0036] Figure 7 To prepare a variable-composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control in Example 1 of this invention 2.24 Cyclic voltammetry curves of the alloy used as an alkaline hydrogen evolution catalyst in 1M KOH. Detailed Implementation

[0037] 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 embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0038] Example 1

[0039] like Figure 1 As shown, the variable composition Mo-Ni alloy (Mo1Ni) with ethanol solvent control. 2.24 The alloy is prepared using the following steps:

[0040] 1) Add 1 mmol nickel nitrate hexahydrate, 0.12 mmol ammonium molybdate tetrahydrate, and 10 mmol urea to 24 mL ethanol solvent and 12 mL ultrapure water, and stir at room temperature for 2 h until a homogeneous solution is formed.

[0041] 2) Transfer the mixed solution from step 1) to a 50 mL high-pressure reactor and place it in an oven. Set the reaction temperature to 150 °C and the reaction time to 6 h.

[0042] 3) After the hydrothermal reaction in step 2) is completed, the product is washed by alternating centrifugation with ultrapure water and ethanol solvent at room temperature. The centrifugation speed is 5000 rpm and the centrifugation time is 5 min. After centrifugation 6 times, the precipitate is collected.

[0043] 4) Place the precipitate collected in step 3) in a vacuum oven and keep it at 40°C for 24 hours. Then collect the product. The obtained product is Mo1Ni. 2.24 Precursor materials for alloys;

[0044] 5) Place the precursor material from step 4) in a tube furnace, with a reaction atmosphere of H2 / Ar, and heat-treat at 500℃ for 2 hours. After the heat treatment process is completed, Mo1Ni with a three-dimensional nano-hierarchical structure can be obtained. 2.24 alloy.

[0045] Example 2

[0046] Variable-composition Mo-Ni alloys (Mo1Ni) controlled by ethanol solvent 4.16 The alloy is prepared using the following steps:

[0047] 1) Add 1 mmol nickel nitrate hexahydrate, 0.12 mmol ammonium molybdate tetrahydrate and 10 mmol urea to 36 mL ethanol solvent, stir at room temperature for 2 h until all particles are dissolved to form a homogeneous solution;

[0048] 2) Transfer the solution prepared in step 1) to a 50mL high-pressure reactor and place it in a heating oven for hydrothermal reaction at 150℃ for 6 hours;

[0049] 3) After the hydrothermal reaction in step 2) is completed, use ultrapure water and ethanol solvent to alternately centrifuge 6 times, with a centrifugation speed of 5000 rpm and a centrifugation time of 5 min, and collect the precipitated reaction product;

[0050] 4) Place the precipitate collected in step 3) in a vacuum oven and keep it at 40°C for 24 hours. Then collect the product. The obtained product is Mo1Ni. 4.16 Precursor materials for alloys;

[0051] 5) Place the precursor material from step 4) in a tube furnace and heat-treat it at 500℃ for 2 hours under an H2 / Ar atmosphere. After the temperature drops to room temperature, Mo1Ni with a three-dimensional nano-hierarchical structure can be obtained. 4.16 alloy.

[0052] Example 3

[0053] Variable-composition Mo-Ni alloys (Mo1Ni) controlled by ethanol solvent 2.87 The alloy is prepared using the following steps:

[0054] 1) Add 1 mmol nickel nitrate hexahydrate, 0.15 mmol ammonium molybdate tetrahydrate, and 15 mmol urea to 6 mL ethanol solvent and 30 mL ultrapure water, and stir at room temperature for 2 h until a homogeneous solution is formed.

[0055] 2) Transfer the mixed solution from step 1) to a 50mL high-pressure reactor and place it in an oven. Set the reaction temperature to 120℃ and the reaction time to 10h.

[0056] 3) After the hydrothermal reaction in step 2) is completed, the product is washed by alternating centrifugation with ultrapure water and ethanol solvent at room temperature. The centrifugation speed is 5000 rpm and the centrifugation time is 5 min. After centrifugation 6 times, the precipitate is collected.

[0057] 4) Place the precipitate collected in step 3) in a vacuum oven and keep it at 40°C for 24 hours. Then collect the product. The obtained product is Mo1Ni. 2.87 Precursor materials for alloys;

[0058] 5) Place the precursor material from step 4) in a tube furnace, with a reaction atmosphere of H2 / Ar, and heat-treat at 500℃ for 2 hours. After the heat treatment process is completed, Mo1Ni with a three-dimensional nano-hierarchical structure can be obtained. 2.87 alloy.

[0059] Example 4

[0060] The preparation steps for a variable-composition Mo-Ni alloy (Mo1Ni1 alloy) controlled by ethanol solvent are as follows:

[0061] 1) Add 1 mmol nickel nitrate hexahydrate, 0.14 mmol ammonium molybdate tetrahydrate, and 12 mmol urea to 20 mL ethanol solvent and 16 mL ultrapure water, and stir at room temperature for 2 h until a homogeneous solution is formed.

[0062] 2) Transfer the mixed solution from step 1) to a 50mL high-pressure reactor and place it in an oven. Set the reaction temperature to 180℃ and the reaction time to 4h.

[0063] 3) After the hydrothermal reaction in step 2) is completed, the product is washed by alternating centrifugation with ultrapure water and ethanol solvent at room temperature. The centrifugation speed is 5000 rpm and the centrifugation time is 5 min. After centrifugation 6 times, the precipitate is collected.

[0064] 4) Place the precipitated reactants collected in step 3) in a vacuum oven and keep them at 40°C for 24 hours. Collect the product. The product obtained is the precursor material of Mo1Ni1 alloy.

[0065] 5) Place the precursor material from step 4) in a tube furnace, with a reaction atmosphere of H2 / Ar, and heat treat it at 650℃ for 2 hours. After the heat treatment process is completed, the Mo1Ni1 alloy with a three-dimensional nano-hierarchical structure can be obtained.

[0066] Example 5

[0067] Variable-composition Mo-Ni alloys (Mo1Ni) controlled by ethanol solvent 3.29 The alloy is prepared using the following steps:

[0068] 1) Add 1 mmol nickel nitrate hexahydrate, 0.14 mmol ammonium molybdate tetrahydrate, and 12 mmol urea to 36 mL of ultrapure water and stir at room temperature for 2 h until a homogeneous solution is formed;

[0069] 2) Transfer the mixed solution from step 1) to a 50mL high-pressure reactor and place it in an oven. Set the reaction temperature to 180℃ and the reaction time to 4h.

[0070] 3) After the hydrothermal reaction in step 2) is completed, the product is washed by alternating centrifugation with ultrapure water and ethanol solvent at room temperature. The centrifugation speed is 5000 rpm and the centrifugation time is 5 min. After centrifugation 6 times, the precipitate is collected.

[0071] 4) Place the precipitated reactants collected in step 3) in a vacuum oven and keep them at 40°C for 24 hours. Collect the product. The product obtained is the precursor material of Mo1Ni1 alloy.

[0072] 5) Place the precursor material from step 4) in a tube furnace, with a reaction atmosphere of H2 / Ar, and heat-treat at 500℃ for 2 hours. After the heat treatment process is completed, Mo1Ni with a three-dimensional nano-hierarchical structure can be obtained. 3.29 alloy.

[0073] Application Example 1

[0074] Study on hydrogen evolution performance of Mo-Ni alloy in alkaline solution.

[0075] The Mo1Ni obtained in Example 1 2.24 Alloy, Mo1Ni obtained in Example 24.16 Alloy materials, Mo1Ni in Examples 3-5 2.87 Alloys, Mo1Ni1 alloys and Mo1Ni 3.29 The alloy and a commercially available Pt / C catalyst were used to prepare working electrodes, with a graphite electrode as the counter electrode and Hg / HgO as the reference electrode. Hydrogen gas was generated by hydrogen evolution reaction in 1M KOH.

[0076] Figure 2 The X-ray diffraction pattern of the material in Example 1 is shown below, indicating that Mo1Ni 2.24 The alloy has a MoNi4 crystal structure. From Figure 3 As can be seen from the scanning electron microscope images, the Mo1Ni prepared in Example 1... 2.24 The alloy morphology consists of an interwoven nanosheet structure and a small amount of nanoparticles; the Mo1Ni alloy was analyzed using transmission scanning electron microscopy. 2.24 The internal microstructure of the alloy was analyzed in detail, and the results are as follows: Figure 4 As shown in (a) of the figure. It can be seen from the figure that Mo1Ni 2.24 The basic building blocks of the alloy are uniformly sized nanoparticles. Figure 4 The medium-energy dispersive X-ray spectroscopy elemental image (b) shows that Mo1Ni 2.24 The two metallic elements Mo and Ni are evenly distributed in the alloy.

[0077] Depend on Figure 5 It can be seen that the catalyst material prepared in Example 1 exhibits excellent hydrogen evolution activity. At a current density of 10 mA cm⁻¹ -2 At that time, its overpotential was only 62mV, close to the hydrogen evolution overpotential of the Pt / C catalyst (45mV). Figure 6 It can be seen that Mo1Ni 2.24 The alloy also exhibits a relatively fast kinetic rate, with a Tafel slope of 56 mV dec. -1 . Figure 7 As shown, even Mo1Ni 2.24 After 100 hours of stability testing, the LSV test curve of the alloy was basically in the same position as the initial LSV test curve, indicating that the Mo1Ni alloy... 2.24 The alloy exhibits good cycle stability.

[0078] The material in Example 2 was subjected to a current density of 10 mA cm⁻¹ -2 At that time, the hydrogen evolution overpotential was 162 mV. The material in Example 3, at a current density of 10 mA / cm², [achieved a similar result]. -2 At that time, the hydrogen evolution overpotential was 92 mV. The material in Example 4 was tested at a current density of 10 mA / cm². -2At that time, the hydrogen evolution overpotential was 165 mV. The catalytic activity of Example 5 was as follows: in 1 M KOH, at a current density of 10 mA / cm², the hydrogen evolution overpotential was 165 mV. -2 At this point, the hydrogen evolution overpotential is 105 mV. Therefore, it can be determined that the compositional regulation caused by the ethanol solvent is the main factor improving the hydrogen evolution catalytic activity of the Mo-Ni alloy in alkaline solution.

[0079] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing ethanol-solvent-regulated variable composition Mo-Ni alloys, characterized by, The method comprises the following steps: S1, dissolving nickel salt, molybdenum salt and urea in a mixed solvent of ethanol and ultrapure water according to a certain stoichiometric ratio, stirring at room temperature to form a uniform mixed solution; S2, placing the mixed solution prepared in step S1 in a constant temperature device and performing heating treatment; S3, after the reaction in step S2 is completed and the solution temperature is reduced to room temperature, the reaction product is washed with ultrapure water and ethanol solvent alternately and repeatedly, and the precipitated product is collected; S4, drying the collected precipitated product in step S3, and the obtained dried product is a variable component Mo-Ni precursor material; S5, performing heat treatment on the variable component Mo-Ni precursor material in step S4 in a H2 / Ar mixed atmosphere, and a variable component Mo-Ni alloy material is obtained. The amount of the mixed solvent is 36 mL per millimole of nickel salt. The reaction temperature in step S2 is 120-180°C, and the reaction time is 4-10 h.

2. The method for preparing a variable-composition Mo-Ni alloy controlled by ethanol solvent according to claim 1, characterized in that, In step S1, the nickel salt is selected from any one of nickel chloride, nickel nitrate or nickel sulfate; and the molybdenum salt is selected from sodium molybdate or ammonium molybdate.

3. The method for preparing an ethanol solvent-regulated variable component Mo-Ni alloy according to claim 1, wherein the molar ratio of the nickel salt, the molybdenum salt and the urea is 1:0.12-0.15:10-15.

4. The method for preparing an ethanol solvent-regulated variable component Mo-Ni alloy according to claim 1, wherein the volume ratio of ethanol to water in the mixed solvent is 1:5-2:

1.

5. The method for preparing a variable-composition Mo-Ni alloy controlled by ethanol solvent according to claim 1, characterized in that, In step S3, the precipitated reaction product is collected by centrifugation, and the drying treatment in step S4 can be low-temperature freeze drying or vacuum drying.

6. The method for preparing a variable-composition Mo-Ni alloy controlled by ethanol solvent according to claim 1, characterized in that, The heat treatment temperature in step S5 is 500-650°C.

7. An ethanol-solvent-regulated variable composition Mo-Ni alloy characterized by, The variable component Mo-Ni alloy is prepared by any one of the preparation methods in claims 1-6.

8. Use of the ethanol-solvent-regulated variable-composition Mo-Ni alloy according to claim 7 for the hydrogen evolution from alkaline electrolytic water, characterized in that, The ethanol solvent-regulated variable component Mo-Ni alloy is used as a cathode hydrogen evolution catalyst.

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