Preparation method of high-crystallinity self-supporting nickel sulfide nanosheet
By using nickel dimethylglyoxime complex as a precursor and combining it with hydrothermal synthesis, highly crystalline self-supporting nickel sulfide nanosheets were prepared, solving the problems of high energy consumption and high cost in existing technologies, and realizing the preparation of efficient catalysts and resource recycling.
Patent Information
- Application Number
- CN202511381118.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-25
- Publication Date
- 2025-12-26
AI Technical Summary
Existing technologies make it difficult to efficiently synthesize nickel sulfide nanosheets that possess both high crystallinity and self-supporting properties, leading to high energy consumption and high cost in the oxygen evolution reaction (OER).
Using nickel dimethylglyoxime complex as a precursor, highly crystalline self-supporting nickel sulfide nanosheets were prepared by hydrothermal synthesis through the slow release of nickel ions and the binding of sulfur ions, thereby inhibiting rapid precipitation and promoting highly ordered crystal growth.
Highly crystalline nickel sulfide nanosheets were prepared, which significantly reduced the reaction overpotential, improved catalytic activity and mechanical stability, and reduced material costs. They are suitable for applications such as hydrogen production by water electrolysis and lithium battery recycling.
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Figure CN121202205A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of hydrogen production catalysts for water electrolysis, and particularly relates to a preparation method of high-crystallinity self-supporting nickel sulfide nanosheets. BACKGROUND
[0002] One of the main difficulties in the current hydrogen production technology by water electrolysis is the high energy consumption and cost of the anode oxygen evolution reaction (OER). OER is a complex process involving four-electron transfer, with slow kinetics, resulting in a very high overpotential required for the reaction, thereby greatly increasing the overall energy consumption and cost. At present, the highly efficient and stable catalysts are severely dependent on noble metals (such as iridium and ruthenium oxides), which have extremely high prices and are scarce in the earth's crust, seriously hindering the large-scale commercial application of the technology. Therefore, the development of non-noble metal OER catalysts is of great significance: it can significantly reduce the material cost of the catalyst, improve the sustainability of resources, and lay a key foundation for the economic feasibility and large-scale development of green hydrogen energy.
[0003] Among various non-noble metal materials, self-supporting nickel sulfide nanosheets with good crystallinity are a kind of OER catalysts with great potential, which exhibit the following core advantages: the highly ordered crystal structure can significantly promote the rapid transmission of electrons, improve the intrinsic conductivity, and thus effectively reduce the reaction overpotential; the self-supporting three-dimensional nanosheet array does not need to use an insulating polymer binder, which not only fully exposes the rich active sites, but also enhances the mechanical stability and durability of the structure, and is not easy to powder and fall off even under a large current density; in addition, the nickel sulfide can optimize the adsorption energy of the reaction intermediates after electrochemical reconstruction, further improving the intrinsic catalytic activity.
[0004] However, the synthesis of such materials still faces important challenges: while regulating the crystal nucleation and growth to achieve high crystallinity, the ultra-thin self-supporting structure needs to be maintained, resulting in the difficulty of existing methods in balancing high crystallinity and ideal two-dimensional morphology.
[0005] Therefore, developing a synthesis method that can efficiently prepare nickel sulfide nanosheets with high crystallinity and self-supporting characteristics has become a key technical problem for promoting its practical application. SUMMARY
[0006] The application provides the following technical solution: a preparation method of high-crystallinity self-supporting nickel sulfide nanosheets, comprising the following steps:
[0007] Step S1, dissolving dimethylglyoxime in anhydrous ethanol to form solution A, and dissolving nickel nitrate hexahydrate in deionized water to form solution B;
[0008] Step S2, stirring after mixing solution A and solution B to generate dimethylglyoxime nickel precipitate;
[0009] Step S3, centrifugal separation of the nickel dimethylglyoxime precipitate, and washing with deionized water and ethanol alternately;
[0010] Step S4, dispersing the purified nickel dimethylglyoxime in the mixed solvent of deionized water and ethanol to obtain a dispersion system;
[0011] Step S5, adding sodium sulfide to the dispersion system obtained in Step S4, and uniformly mixing and then constant-temperature reaction;
[0012] Step S6, after the constant-temperature reaction is completed, naturally cooling to room temperature, centrifugal separation of the solid product and washing with deionized water and ethanol, and vacuum drying to obtain the nickel sulfide electrocatalyst.
[0013] Preferably, in Step S1, the mass-volume ratio of the dimethylglyoxime and anhydrous ethanol is 10-50 mg: 1-5 mL.
[0014] Preferably, in Step S1, the mass-volume ratio of the nickel nitrate hexahydrate and deionized water is 20-50 mg: 1-5 mL.
[0015] Preferably, in Step S2, the stirring time is 10-60 min.
[0016] Preferably, in Step S3, the washing is performed at least 3 times, and centrifugal separation is performed after each washing.
[0017] Preferably, in Step S4, the volume ratio of the deionized water and ethanol is 5-10: 1-5.
[0018] Preferably, in Step S5, the mass-volume ratio of the sodium sulfide and the dispersion system is 10-30 mg: 6-15 mL.
[0019] Preferably, in Step S5, the material of the constant-temperature reaction container is polytetrafluoroethylene, the constant-temperature reaction temperature is 150-200℃, and the constant-temperature reaction time is 4-8 hours.
[0020] Preferably, in Step S6, the washing with deionized water and ethanol is performed 2-8 times.
[0021] Preferably, in Step S6, the vacuum drying temperature is 50-80℃, and the vacuum drying time is 8-24 hours.
[0022] The beneficial effects of the present application are:
[0023] 1. The present application selects nickel dimethylglyoxime complex as a synthetic precursor, instead of nickel nitrate or nickel chloride, which can realize slow release of nickel ions (Ni 2+ ) in the synthesis process, thereby effectively inhibiting Ni 2+ and sulfide ions (S 2-rapid binding and precipitation.
[0024] 2、The application is based on the slow-release strategy of nickel dimethylglyoxime precursor, effectively promoting the growth of highly ordered crystals, thereby successfully preparing two-dimensional NiS nanosheets with significantly improved crystallinity. This unique structure not only exhibits clear lattice fringes, but also has atomic-level thickness and large specific surface area, which is conducive to exposing abundant active sites and shortening the ion / electron transmission path, laying a solid material foundation for improving its performance in electrocatalysis (such as OER) or energy storage applications.
[0025] 3、The advantage of the invention is that the recovery of nickel by dimethylglyoxime precipitation method has high selectivity, high recovery rate and convenient operation. The method can specifically chelate Ni 2+ to form a precipitate, and the recovery rate is usually higher than 97%, and the precipitate can be directly dried and weighed after simple centrifugal separation and washing. This technology is suitable for electroplating wastewater treatment, lithium battery recycling (especially nickel-cobalt separation), alloy composition analysis and other fields. Its core value is to realize efficient recycling of nickel resources through low-cost and low-energy processes. This method is especially suitable for treating industrial wastewater with a nickel concentration of 1-1000 mg / L. The residual nickel concentration after treatment can be reduced to below 0.1 mg / L, meeting the strict environmental emission requirements.
[0026] 4、The method is simple, easy to operate and easy to expand to industrial production. The high-crystallinity self-supporting nickel sulfide nanosheet prepared by the method exhibits catalytic performance comparable to that of noble metal ruthenium oxide in the oxygen evolution reaction, providing an effective solution to the high cost of traditional noble metal catalysts in the field of water electrolysis for hydrogen production. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 is a scanning electron microscope image of the nickel dimethylglyoxime precursor used in the preparation method of the high-crystallinity self-supporting nickel sulfide nanosheet of the present application;
[0028] Figure 2 is a scanning electron microscope image of the nickel sulfide of the present application;
[0029] Figure 3 is an X-ray diffraction pattern of the NiS of the present application;
[0030] Figure 4 is an X-ray diffraction pattern of the NiS2 of the present application;
[0031] Figure 5 is a polarization curve graph of the water electrolysis OER of the nickel sulfide electrocatalyst of the present application in 1.0M KOH solution, and an OER performance graph of a commercial RuO2 nanoparticle electrocatalyst. DETAILED DESCRIPTION
[0032] The related technologies in the present application will be described clearly and completely in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0033] As shown in the present embodiment, the specific steps are as follows: Figures 1 to 5
[0034] S1, 10-50 mg of dimethylglyoxime is dissolved in 1-5 mL of anhydrous ethanol, and 20-50 mg of nickel nitrate hexahydrate is dissolved in 1-5 mL of deionized water to form a homogeneous solution.
[0035] S2, the two solutions obtained in S1 are mixed and stirred at room temperature for 10-60 min to generate a dimethylglyoxime nickel precipitate.
[0036] S3, the precipitate is centrifuged and washed with deionized water and ethanol alternately for at least 3 times, and centrifuged after each washing.
[0037] S4, the precipitate after purification is dispersed in a mixed solvent composed of 5-10 mL of deionized water and 1-5 mL of ethanol;
[0038] S5, 10-30 mg of sodium sulfide is added to the dispersion system, and after uniform mixing, it is transferred to a polytetrafluoroethylene-lined high-pressure reaction kettle, and reacted at 150-200°C for 4-8 hours;
[0039] S6, the reaction system is naturally cooled to room temperature, the solid product is centrifuged, washed with deionized water and ethanol for 3 times in turn, and vacuum dried at 50-80°C for 8-24 hours to obtain the nickel sulfide electrocatalyst.
[0040] In the present embodiment, dimethylglyoxime and nickel nitrate hexahydrate are dissolved and mixed to generate a dimethylglyoxime nickel complex precipitate, which is washed by centrifugation and then mixed with a sodium sulfide solution to prepare self-supported nickel sulfide nanosheets by a hydrothermal synthesis method. The dimethylglyoxime nickel complex is used as a precursor, and by the strategy of slow release of nickel ions (Ni 2+ ), the rapid combination of nickel ions (Ni 2- ) with sulfide ions (S) is inhibited, and the growth of highly ordered crystals is promoted, so that high-crystallinity nickel sulfide nanosheets are finally prepared.
[0041] Embodiment
[0042] 1. Preparation of dimethylglyoxime nickel precursor solution
[0043] Take 23 mg of dimethylglyoxime and dissolve it in 2 mL of ethanol, take 29 mg of nickel nitrate hexahydrate and dissolve it in 2 mL of water, stir at room temperature until completely dissolved. Mix the two and stir well to obtain precipitated nickel dimethylglyoxime.
[0044] 2. Preparation of nickel sulfide electrocatalyst
[0045] After centrifugal washing of the solution stirred in 1, it is redispersed in a water (8 mL) + ethanol (2 mL) solution. Take another 20 mg of sodium sulfide and add it to the solution, stir at room temperature until completely dissolved. Transfer it to a reaction kettle and react at 180 degrees for 6 hours, centrifugal wash and separate the product to obtain a nickel sulfide film electrocatalyst.
[0046] 3. Preparation of 1.0 M KOH solution
[0047] Take 5.61 g of potassium hydroxide and stir to dissolve in 50 mL of ultrapure water, cool and dilute to 100 mL.
[0048] The scanning electron microscope image of nickel dimethylglyoxime prepared in Example 1 is shown in Figure 1 .
[0049] The scanning electron microscope image of nickel sulfide electrocatalyst prepared in Example 1 is shown in Figure 2 , and the X-ray diffraction pattern is shown in Figure 3 .
[0050] As shown in Figure 1 , the nickel dimethylglyoxime is composed of high aspect ratio microrods tightly self-assembled. The microrods are arranged in parallel along the axial direction, and the interface between the rods is clear. This morphology is the result of the synergistic effect of high concentration of precursor and mixed solvent, which is different from the discrete microrods generated by classical slow precipitation.
[0051] The nickel sulfide electrocatalyst prepared in this example is shown in Figure 2 . It shows that nickel dimethylglyoxime and sodium sulfide successfully form nickel sulfide under the action of water bath.
[0052] As shown in Figure 3 , the X-ray diffraction pattern of the NiS electrocatalyst material prepared in this example. Its diffraction peaks at 18.4, 32.2, 35.7 and 40.453 degrees belong to (110), (101), (300) and (211) crystal faces (PDF #00-012-0041) respectively.
[0053] As shown in Figure 4 , the X-ray diffraction pattern of the NiS2 electrocatalyst material prepared in this example. Its diffraction peaks at 31.4, 35.2 and 53.3 degrees belong to (200), (210) and (311) crystal faces (PDF #04-006-5636) respectively.
[0054] 4. The electrocatalyst prepared in the examples was subjected to electrocatalytic reaction test, and the specific steps were as follows:
[0055] (1) Platform building:
[0056] A three-electrode system was used, the working electrode was the nickel sulfide electrocatalyst prepared in the examples, the counter electrode was a Pt electrode, the reference electrode was a Hg / HgO electrode, and the electrolyte was 1.0M KOH;
[0057] (2) Linear sweep voltammetry (LSV) test:
[0058] The test interval was 0.5-0V vs. RHE, and the scan rate was 5mV / s;
[0059] The test results are shown in Figure 4 It can be seen from Figure 4 that after 10 tests, the OER performance of the NiS electrocatalyst gradually stabilized. It has good electrocatalytic oxygen evolution activity in alkaline conditions, and the cathode has an overpotential of 19mV at a current density of 8mA·cm 2 .
[0060] In summary, the nickel dimethylglyoxime complex is selected as a precursor in the present application, instead of nickel nitrate or nickel chloride, which can realize slow release of nickel ions during synthesis, thereby effectively inhibiting the rapid combination of Ni 2+ and sulfur ions and the precipitation to form, so the present application lays a solid material foundation for improving the performance of nickel sulfide nanosheets in electrocatalysis or energy storage applications.
[0061] It should be emphasized that: the above is only a preferred embodiment of the present application, and does not limit the present application in any form, any simple modification, equivalent change and modification of the above examples according to the technical essence of the present application still belongs to the scope of the technical solutions of the present application.
Claims
1. A method for preparing high crystallinity self-supported nickel sulfide nanosheets, characterized in that, The method comprises the following steps: S1, dissolving dimethylglyoxime in anhydrous ethanol to form solution A, and dissolving nickel nitrate hexahydrate in deionized water to form solution B; S2, mixing solution A and solution B and stirring to form nickel dimethylglyoxime precipitate; S3, centrifuging the nickel dimethylglyoxime precipitate and washing it with deionized water and ethanol alternately; S4, dispersing the purified nickel dimethylglyoxime in step S3 in a mixed solvent of deionized water and ethanol to obtain a dispersion system; S5, adding sodium sulfide to the dispersion system obtained in step S4 and uniformly mixing, and then performing constant temperature reaction; S6, after the constant temperature reaction is completed, naturally cooling to room temperature, centrifuging the solid product and washing it with deionized water and ethanol, and vacuum drying to obtain a nickel sulfide electrocatalyst.
2. The method according to claim 1, wherein the method is characterized by, In step S1, the mass-volume ratio of dimethylglyoxime to anhydrous ethanol is 10-50 mg: 1-5 mL.
3. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S1, the mass-volume ratio of nickel nitrate hexahydrate to deionized water is 20-50 mg: 1-5 mL.
4. The method of claim 1, wherein the method is characterized by: In step S2, the stirring time is 10-60 min.
5. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S3, the washing is performed at least 3 times, and centrifuging is performed after each washing.
6. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S4, the volume ratio of deionized water to ethanol is 5-10: 1-5.
7. The method according to claim 1, wherein the method is characterized by, In step S5, the mass-volume ratio of sodium sulfide to the dispersion system is 10-30 mg: 6-15 mL.
8. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S5, the constant temperature reaction container is made of polytetrafluoroethylene, the constant temperature reaction temperature is 150-200℃, and the constant temperature reaction time is 4-8 hours.
9. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S6, the washing with deionized water and ethanol is performed 2-8 times.
10. The method for preparing highly crystalline self-supporting nickel sulfide nanosheets according to claim 1, characterized in that, In step S6, the vacuum drying temperature is 50-80℃, and the vacuum drying time is 8-24 hours.