Preparation method of MoS2 / Co LDHs material and application thereof in supercapacitor
By growing Co LDHs in situ on MoS2, the problems of insufficient conductivity and stability of MoS2 as a supercapacitor electrode material were solved, and the high-performance electrochemical performance and cycle stability of the material were improved.
Patent Information
- Application Number
- CN202211706004.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-29
- Publication Date
- 2026-01-09
- Estimated Expiration
- 2042-12-29
AI Technical Summary
Existing MoS2 as an electrode material for supercapacitors suffers from poor conductivity and cycling stability, is prone to agglomeration, and generates sulfides during cycling, leading to capacity decay.
By growing Co LDHs in situ on MoS2 and then transforming them into Co LDHs using ZIF-67 water etching, the use of binders is avoided, thereby improving the conductivity and specific surface area of the material and enhancing the electron transport rate.
This effectively solves the problem of easy aggregation of MoS2, improves the electrochemical performance and cycle stability of the material, and enhances the capacitance performance of supercapacitors.
Smart Images
Figure SMS_1 
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of supercapacitors, and relates to a supercapacitor electrode material, in particular to a MoS2 / Co LDHs material. BACKGROUND
[0002] An ideal supercapacitor electrode material should have good hydrophilicity, high conductivity, large specific surface area, large interlayer spacing and high stability, and be pollution-free to the environment, and the supercapacitor has been widely concerned as a recognized green energy storage device.
[0003] Zeolitic imidazolate frameworks (ZIFs) as a new subclass of metal-organic frameworks (MOFs) have large specific surface area, high thermal stability, structural flexibility and adjustable pore size, and have been recognized as ideal templates for ordered structure metal hydroxides. ZIF-67 is composed of connected cobalt cations and 2-methylimidazolate anions, and is one of the most representative ZIFs with sodalite zeolite topology structure. ZIF-67 can not only be used as a sacrificial template to construct dodecahedron structures, but also be used as a cobalt source with variable valence to construct Co LDHs. Benefiting from its suitable thermal behavior and chemical reactivity, various metal hydroxides can be easily obtained by direct thermal decomposition of ZIF-67.
[0004] Transition metal dichalcogenides (TMDs) can be considered as a typical quasi-two-dimensional material, and the intermediate layer is bonded by weak van der Waals force, allowing foreign ions to be embedded. For example, molybdenum disulfide (MoS2), which is composed of Mo atoms sandwiched between two layers of S atoms. S-Mo-S layers are stacked by van der Waals force, and the interlayer spacing is 0.62 nm. The unique two-dimensional structural feature provides sufficient space for accommodating foreign ions, so that MoS2 has high electrical activity and has attracted wide scientific and technological interest in electrochemical energy storage applications. However, MoS2 has its own shortcomings as an electrode material. First, the conductivity and cycle stability of MoS2 are not satisfactory. Second, MoS2 will produce sulfides during the cycle process, which is partly the cause of capacity attenuation. Finally, the volume expansion and contraction of MoS2 further limit the commercial application of MoS2.
[0005] Therefore, it is of great significance to obtain a high-performance molybdenum sulfide-based supercapacitor, to make Co LDHs grow uniformly and stably on molybdenum disulfide, and to improve the electrochemical performance of the two materials by compounding to make an energy storage device. SUMMARY
[0006] The purpose of the present application is to overcome the defects of molybdenum disulfide as an electrode material, provide a MoS2 / Co LDHs material for supercapacitor electrode, which is composed of molybdenum disulfide as a substrate and Co LDHs in situ growth, ZIF-67 is converted into Co LDHs by water etching, Co LDHs in the material is uniformly grown on the MoS2 substrate, effectively solving the defect of easy agglomeration of MoS2, at the same time, Co LDHs and MoS2 are in situ compounded, avoiding the use of binder, which is beneficial to the improvement of the conductivity of the material, so as to obtain a supercapacitor with more excellent performance.
[0007] Another purpose of the present application is to provide a preparation method of Co LDHs material, by improving the solvent in the synthesis of ZIF-67, making ZIF-67 be converted into Co LDHs by water etching, making it more easily and uniformly grow on the substrate, effectively improving the specific surface area of the material, providing more active sites, improving the transmission rate of electrons, and the electrode material is beneficial to obtain excellent electrochemical performance.
[0008] Another purpose of the present application is to provide a preparation method of MoS2 / Co LDHs material, which is simple and efficient, low in synthesis cost, and has considerable commercial value.
[0009] In order to achieve the above purpose, the technical scheme of the present application is as follows:
[0010] A preparation method of MoS2 / Co LDHs material, comprising the following operation steps:
[0011] (1) 1-2g sodium oleate, 0.5-1.5g molybdate and 0.5-1.5g sulfur source are ultrasonically dispersed in a mixed solution of deionized water, ethanol and oleic acid, the pH value is adjusted to 1.0-1.5 by using acid, and hydrothermal reaction is carried out, then centrifugation, washing and vacuum drying are carried out to obtain flaky molybdenum disulfide;
[0012] The volume ratio of deionized water, ethanol and oleic acid in the mixed solution is 5:5:1, and the total volume of the mixed solution is 33mL;
[0013] (2) 0.09-0.15g of cobalt salt and 1.8-2.5g of 2-methylimidazole are ultrasonically dispersed in 25mL of deionized water, then 0.005-0.055g of molybdenum disulfide prepared in step (1) is added, fully stirred and reacted, and aged for a period of time, then centrifuged, washed and vacuum dried to obtain MoS2 / Co LDHs material.
[0014] Further, the molybdate in step (1) is a common molybdenum source, specifically, such as anhydrous sodium molybdate, ammonium molybdate tetrahydrate, potassium molybdate.
[0015] Further, the sulfur source of step (1) is a common sulfur source, specifically such as thiourea, thioacetamide, L-cysteine.
[0016] Further, the acid of step (1) is a common acid, specifically such as hydrochloric acid, nitric acid.
[0017] Further, the concentration of molybdate in the mixed solution of step (1) is 10-30 mg / mL.
[0018] Further, the concentration of sulfur source in the mixed solution of step (1) is 5-25 mg / mL.
[0019] Further, the concentration of oleate in the mixed solution of step (1) is 15-50 mg / mL.
[0020] Further, the hydrothermal reaction of step (1) is carried out in a reaction kettle, the solution accounts for 70% of the volume of the PTFE liner, and then reacted at 160-200℃ for 12-36 hours.
[0021] Further, the cobalt salt of step (2) is a common cobalt salt, specifically such as cobalt nitrate hexahydrate, cobalt chloride hexahydrate.
[0022] Further, the concentration of cobalt salt in the solution of step (2) is 1-15 mg / mL.
[0023] Further, the concentration of 2-methylimidazole in the solution of step (2) is 70-90 mg / mL.
[0024] Further, the concentration of molybdenum disulfide in the solution of step (2) is 0.2-2.2 mg / mL.
[0025] Further, the reaction and aging of step (2) is carried out at room temperature for 3-10 hours.
[0026] Further, in the preparation method of the MoS2 / Co LDHs material, the washing of steps (1) and (2) is first washed with deionized water and centrifuged 3 times, and then washed with anhydrous ethanol and centrifuged 3 times.
[0027] Further, the prepared MoS2 / Co LDHs material is applied in supercapacitors or hybrid capacitors.
[0028] Compared with the prior art, the preparation method of the present application has the following beneficial technical effects:
[0029] 1、The MoS2 nanosheet synthesized by the one-step hydrothermal method can provide high charge storage surface area due to its two-dimensional sheet structure, and can improve the capacitance performance of the electrode material. More importantly, the nanosheet of MoS2 as a support material can provide higher ion conductivity and mechanical stability. Therefore, the MoS2 nanosheet and the nanosized Co LDHs material can provide satisfactory electrode material performance.
[0030] 2、The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0031] 3、The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0032] 4、The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value. BRIEF DESCRIPTION OF DRAWINGS
[0033] Figure 1 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0034] Figure 2 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0035] Figure 3 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0036] Figure 4 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0037] Figure 5 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0038] Figure 6 The MoS2 / Co LDHs material is successfully prepared by directly growing the Co LDHs on the MoS2 surface through the one-step coprecipitation method, the method is simple and efficient in operation, and has low synthesis cost and considerable commercial value.
[0039] Figure 7 This is a high-magnification TEM image of a MoS2 / Co LDHs material according to an embodiment of the present invention;
[0040] Figure 8 This is an elemental distribution diagram of a MoS2 / Co LDHs material according to an embodiment of the present invention;
[0041] Figure 9 This is a comparative XRD pattern of MoS2 / Co LDHs material from a control embodiment of the present invention.
[0042] Figure 10 This is a cyclic voltammetry comparison diagram of a MoS2 / Co LDHs material according to an embodiment of the present invention;
[0043] Figure 11 This is a charge-discharge curve of a MoS2 / Co LDHs material according to an embodiment of the present invention;
[0044] Figure 12 An impedance diagram of a MoS2 / Co LDHs material according to an embodiment of the present invention;
[0045] Figure 13 This is an N2 adsorption-desorption isotherm of a MoS2 / Co LDHs material according to an embodiment of the present invention; Detailed Implementation
[0046] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.
[0047] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.
[0048] Example 1
[0049] A method for preparing MoS2 / Co LDHs materials includes the following steps:
[0050] Step 1): Dissolve 1.6g sodium oleate, 1.0g anhydrous sodium molybdate, and 0.9g thiourea evenly in a mixed solution made of 15mL water, 15mL ethanol, and 3mL oleic acid.
[0051] Step 2): Adjust the pH of the well-stirred mixture to 1.0 using a 2.0M HCl aqueous solution;
[0052] Step 3): Then pour the mixture into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75 ml, and the volume accounts for 70% of the total volume;
[0053] Step 4): After sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product is first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of flaky molybdenum disulfide;
[0054] Step 5): 0.15g of cobalt nitrate hexahydrate and 2.2g of 2-methylimidazole are ultrasonically dispersed in 25mL of deionized water, then 0.025g of molybdenum disulfide prepared in step (4) is added, and stirred uniformly for 15 minutes;
[0055] Step 6): After standing and aging at room temperature for 6 hours, the generated product is first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of MoS2 / CoLDHs material.
[0056] Example 2
[0057] A method for preparing a MoS2 / Co LDHs material, comprising the following operation steps:
[0058] Step 1): 1.6g of sodium oleate, 0.86g of ammonium molybdate tetrahydrate, and 1.5g of thioacetamide are uniformly dissolved in a mixed solution prepared from 15mL of water, 15ml of ethanol, and 3ml of oleic acid;
[0059] Step 2): Adjust the pH value of the uniformly stirred mixture to 1.1 using 2.0M HNO3 aqueous solution;
[0060] Step 3): Then pour the mixture into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75 ml, and the volume accounts for 70% of the total volume;
[0061] Step 4): After sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product is first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of flaky molybdenum disulfide;
[0062] Step 5): 0.12g of cobalt chloride hexahydrate and 2.2g of 2-methylimidazole are ultrasonically dispersed in 25mL of deionized water, then 0.035g of molybdenum disulfide prepared in step (4) is added, and stirred uniformly for 15 minutes;
[0063] Step 6): After standing, aging for 6 hours at room temperature, the generated product is washed with distilled water, centrifugal filtration 3 times, then washed with anhydrous ethanol, centrifugal filtration 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the MoS2 / Co LDHs material target product.
[0064] Example 3
[0065] A method for preparing a MoS2 / Co LDHs material, comprising the following operation steps:
[0066] Step 1): 1.6g of sodium oleate, 1.0g of anhydrous sodium molybdate, and 1.5g of L-cysteine are uniformly dissolved in a mixed solution made of 15mL of water, 15ml of ethanol, and 3ml of oleic acid;
[0067] Step 2): The pH value of the uniformly stirred mixture is adjusted to 1.2 using 2.0M HCL aqueous solution;
[0068] Step 3): Then the mixture is poured into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75ml, which accounts for 70% of the total volume;
[0069] Step 4): After sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product is first washed with deionized water, centrifugal filtration 3 times, then washed with anhydrous ethanol, centrifugal filtration 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of sheet-shaped molybdenum disulfide;
[0070] Step 5): 0.15g of cobalt nitrate hexahydrate and 2.2g of 2-methylimidazole are ultrasonically dispersed in 25mL of deionized water, then 0.045g of molybdenum disulfide prepared in step (4) is added, and stirred for 15 minutes until uniform;
[0071] Step 6): After standing, aging for 6 hours at room temperature, the generated product is first washed with deionized water, centrifugal filtration 3 times, then washed with anhydrous ethanol, centrifugal filtration 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the MoS2 / Co LDHs material target product.
[0072] Example 4
[0073] A method for preparing a MoS2 / Co LDHs material, comprising the following operation steps:
[0074] Step 1): 1.6g of sodium oleate, 1.0g of anhydrous sodium molybdate, and 0.9g of thiourea are uniformly dissolved in a mixed solution made of 15mL of water, 15ml of ethanol, and 3mL of oleic acid;
[0075] Step 2): Adjust the pH value of the stirred mixture to 1.0 using 2.0M HNO3 aqueous solution;
[0076] Step 3): Then pour the mixture into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75ml, which accounts for 70% of the total volume;
[0077] Step 4): After sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product is first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of flaky molybdenum disulfide;
[0078] Step 5): Ultrasonically disperse 0.15g of cobalt nitrate hexahydrate and 2.2g of 2-methylimidazole in 25mL of deionized water, then add 0.005g of molybdenum disulfide prepared in step (4) to it, and stir for 15 minutes until uniform;
[0079] Step 6): Stand and age at room temperature for 4 hours, and then wash the generated product with deionized water, centrifuge and filter 3 times, then wash with anhydrous ethanol, centrifuge and filter 3 times, and dry in a vacuum drying oven at 60°C for 6 hours to obtain the target product of MoS2 / CoLDHs material.
[0080] Example 5
[0081] A method for preparing a MoS2 / Co LDHs material, comprising the following operation steps:
[0082] Step 1): Dissolve 1.6g of sodium oleate, 1.0g of anhydrous sodium molybdate, and 1.5g of thioacetamide in a mixed solution prepared from 15mL of water, 15ml of ethanol, and 3ml of oleic acid;
[0083] Step 2): Adjust the pH value of the stirred mixture to 1.2 using 2.0M HCL aqueous solution;
[0084] Step 3): Then pour the mixture into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75ml, which accounts for 70% of the total volume;
[0085] Step 4): After sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product is first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6∶20 hours to obtain the target product of flaky molybdenum disulfide;
[0086] Step 5): Disperse 0.15g of cobalt nitrate hexahydrate and 2.2g of 2-methylimidazole in 25mL of deionized water by ultrasonication, then add 0.045g of molybdenum disulfide prepared in step (4) and stir thoroughly for 15 minutes until homogeneous;
[0087] Step 6): Let the product stand and age at room temperature for 4 hours. Wash the product with deionized water and centrifuge and filter it 3 times. Then wash it with anhydrous ethanol and centrifuge and filter it 3 times. Dry it in a vacuum drying oven at 60°C for 6:20 hours to obtain the target product of MoS2 / Co LDHs material.
[0088] Comparative Example 1
[0089] Compared with Example 1, the difference is that no molybdenum disulfide matrix was added, and ZIF-67 was synthesized directly. The specific preparation process is as follows:
[0090] Step 1): Disperse 0.15g of cobalt nitrate hexahydrate and 2.2g of 2-methylimidazole in 25mL of deionized water by ultrasonication, then add 0.025g of molybdenum disulfide prepared in step (4) and stir thoroughly for 15 minutes until homogeneous;
[0091] Step 2): Let the product stand and age at room temperature for 6 hours. Wash the product with deionized water and centrifuge and filter it 3 times. Then wash it with anhydrous ethanol and centrifuge and filter it 3 times. Dry it in a vacuum drying oven at 60°C for 6 hours to obtain the target product of MoS2 / CoLDHs material.
[0092] Depend on Figure 3 It can be seen that it is leaf-shaped, unlike the dodecahedron in general literature. This is because the common methanol solvent is replaced with a water solvent, at 1A g -1 The specific capacitance of the material under the current is 171 F g. -1 MoS2 / Co LDHs materials in 1Ag -1 The specific capacitance of the material under the current is 279 F g. -1 The value was significantly higher than that of the unmodified variety.
[0093] Comparative Example 2
[0094] Compared to Example 1, the difference lies in increasing the concentrations of nitrate and 2-methylimidazole. The specific preparation process is as follows:
[0095] Step 1): Dissolve 1.6g sodium oleate, 1.0g anhydrous sodium molybdate, and 0.9g thiourea evenly in a mixed solution made of 15mL water, 15mL ethanol, and 3mL oleic acid.
[0096] Step 2): Adjust the pH of the well-stirred mixture to 1.3 using a 2.0M HCl aqueous solution;
[0097] Step 3): Then the mixture was poured into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75 ml, which accounted for 70% of the total volume;
[0098] Step 4): After sealing, the autoclave was transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product was first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of flaky molybdenum disulfide;
[0099] Step 5): 0.3g of cobalt nitrate hexahydrate and 4.4g of 2-methylimidazole were ultrasonically dispersed in 25mL of deionized water, then 0.025g of molybdenum disulfide prepared in step (4) was added, and stirred for 15 minutes until uniform;
[0100] From Figure 4 It can be seen that due to the increase of the concentration of cobaltate, a large number of cobalt ions are not adsorbed on the molybdenum disulfide matrix by electrostatic adsorption, and Co LDHs are not uniformly grown on MoS2, which are obviously separated. The specific capacitance of the material is 203.7Fg -1 under a current of 1Ag -1 , while the specific capacitance of the MoS2 / Co LDHs material is 279F g -1 under a current of 1Ag -1 , which is significantly higher than that of the unmodified.
[0101] Comparative Example 3
[0102] Compared with Example 1, the difference is that mechanical grinding is used instead of in-situ growth. The specific preparation process is as follows:
[0103] Step 1): 1.6g of sodium oleate, 1.0g of anhydrous sodium molybdate, and 0.9g of thiourea were uniformly dissolved in a mixed solution prepared from 15mL of water, 15ml of ethanol, and 3ml of oleic acid;
[0104] Step 2): Adjust the pH value of the uniformly stirred mixture to 1.0 using 2.0M aqueous HCl solution;
[0105] Step 3): Then the mixture was poured into a stainless steel autoclave lined with polytetrafluoroethylene with a volume of 75 ml, which accounted for 70% of the total volume;
[0106] Step 4): After sealing, the autoclave was transferred to a blast drying oven at 180°C for 24 hours, and naturally cooled to room temperature. The precipitated product was first washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product of flaky molybdenum disulfide;
[0107] Step 5): 0.3 g of cobalt nitrate hexahydrate and 4.4 g of 2-methylimidazole were ultrasonically dispersed in 25 mL of deionized water, the product was washed with deionized water, centrifuged and filtered 3 times, then washed with anhydrous ethanol, centrifuged and filtered 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain the target product ZIF-67;
[0108] Step 6): The molybdenum disulfide material of step 4) and the ZIF-67 of step 5) were uniformly ground in a mortar at a mass ratio of 1:3 for 10 minutes to obtain the target product MoS2 / Co LDHs.
[0109] At a current of 1 Ag -1 , the specific capacitance of the material was 245.2 F g -1 , and at a current of 1 Ag -1 , the specific capacitance of the MoS2 / Co LDHs material was 280.4 F g -1 , which indicated that the MoS2 / Co LDHs material was not excellent between the two, but showed better synergy.
[0110] Results and discussion:
[0111] Scanning electron microscopy characterization of MoS2 / Co LDHs material:
[0112] Figure 2 is the scanning electron microscopy image of pure molybdenum disulfide, it can be observed that the molybdenum disulfide prepared by this method is uniform in sheet shape, the substrate has a large specific area, and the thickness is about 7.5 nm, Figure 3 is the SEM image of Co LDHs of the one pair of examples of the present application, Figure 4 is the SEM image of MoS2 / Co LDHs of the two pairs of examples of the present application, Figure 5 is the SEM image of MoS2 / Co LDHs of the two embodiments of the present application, and Figure 4 It can be seen that when the concentration of cobalt salt is increased, leaf-shaped ZIF-67 with a length of about 10 microns is generated, but most of them grow outside the MoS2 substrate, and the two cannot be uniformly combined. Figure 5 、 Figure 6 It can be observed that the Co LDHs grown on the molybdenum disulfide substrate are transparent and have a nano-layered morphology with different pore sizes, greatly improving the specific surface area of the material and thus improving the electrical properties of the material. With the increase of the addition amount of molybdenum disulfide, the Co LDHs grown originally become thicker, improving its cycle stability.
[0113] Electrochemical performance of MoS2 / Co LDHs material:
[0114] The MoS2 / Co LDHs material prepared in Example 1-Example 3 has the most preferred performance effect, the process effect of Example 4 and Example 5 is better, and the MoS2 / Co LDHs material prepared in Example 1 is taken as an example below, and the MoS2 / Co LDHs material is made into a positive electrode material, and then the three-electrode system is constructed and compared with the comparative examples.
[0115] Preparation of the positive electrode material: the MoS2 / Co LDHs material prepared in Example 1, acetylene black and polyvinylidene fluoride are added and ground in alcohol to obtain a homogeneous black slurry, the black slurry is uniformly laid on the foamed nickel, and then dried and pressed to obtain the positive electrode material; wherein the mass ratio of the MoS2 / Co LDHs material, the conductive acetylene black and the polyvinylidene fluoride is 8:1:1;
[0116] The ZIF-67 of Comparative Example 1 and the MoS2 of Comparative Example 2 are also made into positive electrode materials by the same method.
[0117] The composition of the three-electrode system is as follows: a CHI760 electrochemical workstation is used, a platinum sheet is used as a counter electrode, a mercury oxide electrode is used as a reference electrode, and the electrode materials of Example 1, Comparative Example 1 and Comparative Example 2 are used as working electrodes respectively to test the electrochemical performance, and the electrolyte is a 3 mol / L KOH solution.
[0118] Figure 9 The cyclic voltammograms of MoS2, ZIF-67 and MoS2 / Co LDHs under the condition of 5mV s -1 -1, and the figure shows that the electrical performance of ZIF-67 of Comparative Example 1 or MoS2 of Comparative Example 2 is obviously different from that of the MoS2 / Co LDHs material of Example 1, which also shows that the MoS2 / Co LDHs material is not an excellent material between the two, but shows a better synergistic effect.
[0119] Figure 10 The results show that under the current of 1Ag -1 -1, the charge and discharge performance of ZIF-67 of Comparative Example 1, MoS2 of Comparative Example 2 and MoS2 / Co LDHs material of Example 1 is 94.2F g -1 -1, 171F g -1 -1 and 280.4F g -1 -1 respectively, which is three times higher than that of the pure molybdenum disulfide coated material, and plays a significant role in modifying molybdenum disulfide.
[0120] To explore the effect of different MoS2 addition amount on MoS2 / Co LDHs material, the addition amount was adjusted to 5 mg, 25 mg, and 45 mg, respectively, to prepare MoS2 / Co LDHs-1, MoS2 / Co LDHs-2, and MoS2 / Co LDHs-3 corresponding to the materials of Example 4, Example 1, and Example 5, and the electrochemical performance thereof was tested, and the corresponding values are listed in Table 1.
[0121] Table 1: Capacitance of MoS2 / Co LDHs prepared by different MoS2 addition amounts
[0122]
[0123] As can be seen from the table, with the increase of MoS2 addition amount, the specific capacitance gradually increases and then decreases. This is because the MoS2 addition amount is too small in the early stage, a large number of cobalt ions are free to generate ZIF-67, and the electrochemical performance of ZIF-67 is poor, thereby resulting in low specific capacitance content. When the MoS2 addition amount gradually increases, Co LDHs is successfully coated on MoS2 to achieve the best performance. When the MoS2 addition amount increases again, the material's electrochemical performance is reduced due to the easy agglomeration of MoS2. The rate performance gradually increases because MoS2 has good stability, and the more it increases, the better the relative rate performance is. In summary, according to the combination of Example 1, the MoS2 / Co LDHs-2 has the best comprehensive electrical performance.
[0124] Figure 12 It is shown that the specific surface area of MoS2 / Co LDHs is excellent. Since Co LDHs is a layered structure, the accumulation of MoS2 nanosheets is reduced, and the specific surface area is increased. Barrett-Joyner-Halenda (BJH) type calculation results show that the specific surface area is 292.4 m 2 g -1 . The average pore size of the sample is 8.28 nm, and the maximum pore size of the sample size ratio is about 391 nm. The pore between the organic metal-metal skeleton and the layered structure is large, thereby increasing the ion transport channel, shortening the transport path, and providing more reaction sites, thereby reducing the resistance, increasing the specific capacitance, and improving the electrochemical performance at high scanning rate. MoS2 / Co LDHs material has a rich mesoporous and macroporous hierarchical pore structure, and is an electrode suitable for energy storage applications.
[0125] In conclusion, the preparation method can effectively synthesize the MoS2 / Co LDHs material, has excellent specific surface area, provides more active sites, improves the transmission rate of electrons, and the electrochemical performance is increased by 197.6% and 64% respectively compared with MoS2 and ZIF-67 material, the ZIF-67 etched into Co LDHs coated MoS2 is first created, the layered hydroxide provides support for MoS2, has excellent electrochemical performance and cycle performance, the whole method is simple and efficient, the synthesis cost is low, and has considerable commercial value.
[0126] It is understood by those skilled in the art that the above examples are only examples, wherein the features of different examples can be combined with each other to obtain embodiments which are easily thought of according to the disclosure of the present application but are not explicitly indicated in the drawings, and the present application does not limit this.
[0127] It is understood by those skilled in the art that the above description and the embodiments of the present application shown in the drawings are only examples and do not limit the present application. The purpose of the present application has been completely and effectively achieved. The function and structural principle of the present application have been shown and described in the embodiments, and the embodiments of the present application can have any modification or change without departing from the principle.
Claims
1. A method for preparing a MoS2 / Co LDHs material, characterized in that, The method comprises the following steps: (1) uniformly dispersing 0.5-1.5 g of molybdate, 0.5-1.5 g of sulfur source and 1-2 g of sodium oleate in a mixed solution of water, ethanol and oleic acid, adjusting the pH value to 1.0-1.5 using an acid, and then performing a hydrothermal reaction, and then washing with deionized water, centrifugal filtration 3 times, washing with anhydrous ethanol, centrifugal filtration 3 times, and vacuum drying to obtain flaky molybdenum disulfide; the mixed solution comprises 15 mL of water, 15 mL of ethanol and 3 mL of oleic acid; the hydrothermal reaction is performed in a reaction kettle, the solution occupies 70% of the volume of the polytetrafluoroethylene liner, and then the reaction is performed at 160-200°C for 12-36 hours; (2) ultrasonically dispersing 0.09-0.15 g of cobaltate and 1.8-2.5 g of 2-methylimidazole in 25 mL of deionized water, then adding 0.005-0.055 g of molybdenum disulfide prepared in step (1), fully stirring and uniformly reacting, and aging for a period of time, first washing with deionized water, centrifugal filtration 3 times, then washing with anhydrous ethanol, centrifugal filtration 3 times, and drying for 6 hours to obtain a MoS2 / Co LDHs material; the concentration of the cobaltate in the solution is 1-15 mg / mL; the reaction and aging for a period of time are performed at room temperature for 3-10 hours.
2. The method for preparing MoS2 / Co LDHs material according to claim 1, characterized in that, The molybdate in step (1) is one of anhydrous sodium molybdate, ammonium molybdate tetrahydrate and potassium molybdate.
3. The method for preparing MoS2 / Co LDHs material according to claim 1, characterized in that, The sulfur source in step (1) is one of thiourea, thioacetamide and L-cysteine.
4. The method for preparing MoS2 / Co LDHs material according to claim 1, characterized in that, The acid in step (1) is one of hydrochloric acid and nitric acid.
5. The method of claim 1, wherein the MoS2 / Co LDHs material is prepared by the method comprising: The cobaltate in step (2) is one of cobalt nitrate hexahydrate and cobalt chloride hexahydrate.
6. A method for preparing a MoS2 / Co LDHs material, characterized in that, 1.6 g of sodium oleate, 1.0 g of anhydrous sodium molybdate and 0.9 g of thiourea are uniformly dissolved in a mixed solution prepared from 15 mL of water, 15 mL of ethanol and 3 mL of oleic acid; 2.0 M HCl aqueous solution is used to adjust the pH value of the uniformly stirred mixture to 1.0; then the mixture is poured into a stainless steel autoclave with a polytetrafluoroethylene liner with a volume of 75 mL, which occupies 70% of the total volume; after sealing, the autoclave is transferred to a blast drying oven at 180°C for 24 hours, and then naturally cooled to room temperature; the precipitated product is first washed with deionized water, centrifugal filtration 3 times, then washed with anhydrous ethanol, centrifugal filtration 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain flaky molybdenum disulfide target product; 0.15 g of cobalt nitrate hexahydrate and 2.2 g of 2-methylimidazole are ultrasonically dispersed in 25 mL of deionized water, then 0.025 g of the prepared molybdenum disulfide is added, fully stirred for 15 minutes to uniformity; at room temperature, the product is aged for 6 hours, first washed with deionized water, centrifugal filtration 3 times, then washed with anhydrous ethanol, centrifugal filtration 3 times, and dried in a vacuum drying oven at 60°C for 6 hours to obtain a MoS2 / Co LDHs material target product.
7. The MoS2 / Co LDHs material prepared according to the preparation method of claim 1 or 6, characterized in that, It is applied in supercapacitors or hybrid capacitors.