A ZIF-67-derived hollow Co9S8 composite material grown in situ on a rod-shaped radial cluster of CoO and its preparation method.

Abstract

This invention relates to an in-situ growth method of ZIF-67-derived hollow Co9S8 composite material on rod-shaped radial clusters of CoO and its preparation method. The technical solution is as follows: Co(NO3)2·6H2O, NF4F, and CH4N2O are dissolved in 20 mL of deionized water under stirring, transferred to a reaction vessel, and nickel foam (NF) is added. The mixture is maintained at 120℃ for 9 h, followed by carbonization at 350℃ for 1 h to obtain spiky CoO. The target product, Co9S8@CoO-NF composite material, is then obtained through in-situ growth and sulfidation. This invention uses a hydration-carbonization-in-situ growth-sulfidation method to prepare a 3D hollow rod-shaped radial cluster composite electrode material. Three-electrode testing shows that at a current density of 5 mA cm⁻¹... ‑2 At that time, the capacitance of the electrode material reached 18.13 F cm. ‑2 (2952F g ‑1 The preparation process of Co9S8@CoO composite material is simple, easy to implement, and inexpensive, making it suitable as an electrode material for supercapacitors.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor electrode material preparation technology, specifically relating to a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO and its preparation method. Background Technology

[0002] With the rapid development of the new energy sector, there is an urgent need for high-performance energy storage devices (lithium-ion batteries, supercapacitors, etc.). Currently, supercapacitors are considered one of the most commercially promising energy storage devices. However, the relatively low energy density of supercapacitors limits their practical application. This is explained by the formula E = 1 / 2CV. 2 It is known that the energy density of a supercapacitor is determined by the electrode capacitance and voltage window. Therefore, the rational design and construction of electrode materials is one of the effective methods to achieve high energy density in supercapacitors.

[0003] Transition metal oxides (RuO2, CoO, etc.) have been widely reported as electrode materials for supercapacitors. Among them, the theoretical capacitance of the CoO electrode is as high as 4292 F g. -1 CoO is an ideal high-performance pseudocapacitive electrode material. However, in applications, CoO electrodes exhibit low conductivity and slow electron transport, failing to achieve the theoretically high capacitance. Studies have confirmed that constructing heterostructures of transition metal compounds can adjust the electronic structure, improve conductivity, and induce rapid interfacial electron transport, thereby promoting reaction kinetics. Simultaneously, the effective synergistic effect between different components promotes electron transfer and ion diffusion. Although constructing heterostructures of transition metal compounds can effectively improve the electrochemical performance of electrode materials, problems such as poor structural stability and undesirable volume changes still exist during electrochemical reactions.

[0004] The structure of electrode materials is also a factor affecting the electrochemical performance of supercapacitors. Hollow structures, in particular, can mitigate volume and stress changes caused by electrochemical reactions and increase the contact area between the electrolyte and the electrode material. A common method for preparing hollow structures is the template method, including sacrificial template methods using SiO2 and ZIF-67. ZIF-67 is a porous network material composed of organic ligands and inorganic metal ions, belonging to the subclass of metal-organic frameworks (MOFs). Using ZIF-67 as a sacrificial template to prepare hollow electrode materials can effectively utilize the advantages of the ZIF-67 structure, such as its large specific surface area, excellent pore structure, and ease of synthesis, to achieve high electrochemical performance. Unfortunately, pure hollow structures are prone to aggregation as electrode materials, reducing the specific surface area and hindering ion diffusion and electron transport. Therefore, designing and constructing reasonable electrode material structures remains challenging. Summary of the Invention

[0005] To address the aforementioned issues, this invention utilizes CoO-NF as a precursor and, through in-situ growth and sulfidation, prepares a supercapacitor electrode material with high stability and high energy density. This invention also provides a hollow Co9S8 composite material derived from ZIF-67 grown in situ on rod-shaped radial clusters of CoO and its preparation method.

[0006] To achieve the above technical objectives, the technical solution adopted in this application is as follows:

[0007] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0008] 1) Pre-treat the nickel foam (NF);

[0009] 2) Mix Co(NO3)2·6H2O, NH4F, CH4N2O and deionized water, stir at room temperature for 5-10 min to obtain a pink mixed solution, and pour it into a reaction vessel;

[0010] 3) Immerse the treated nickel foam (NF) in the above mixed solution, keep it at 100-150℃ for 8-10 hours, take out the NF, wash and dry it, and then carbonize it to obtain the CoO-NF precursor.

[0011] 4) Dissolve 2-methylimidazole in a mixed solution of anhydrous ethanol and deionized water, sonicate at room temperature until dissolved, add CoO-NF precursor, let stand at room temperature for 22-25 h, wash and dry to obtain ZIF-67@CoO-NF precursor;

[0012] 5) Sonicate thioacetamide (CH3CSNH2) and anhydrous ethanol at room temperature for 3-10 minutes until the thioacetamide dissolves to obtain a mixed solution, and pour it into a reaction vessel;

[0013] 6) Place the ZIF-67@CoO-NF precursor into a reactor, keep it at 100-150℃ for 3-5 hours, let it stand to room temperature, wash and dry to obtain the target product Co9S8@CoO-NF.

[0014] 7) Electrochemical performance tests were performed on the target product Co9S8@CoO-NF.

[0015] Further, in step 1), the pretreatment method of NF is as follows: First, cut NF into pieces of size 1×1.5cm, then place NF in acetone, anhydrous ethanol, and deionized water in sequence and sonicate for 10-30min respectively, with an ultrasonic frequency of 20-40KHz. After removal, dry in a vacuum drying oven at 50℃ for 7-9h.

[0016] Further, in step 2), the mass ratio of Co(NO3)2·6H2O, NH4F and CH4N2O is 2:1:2, and the amount of deionized water is 10-30 mL.

[0017] Further, in step 3), the carbonization step involves transferring the treated NF into a tube furnace and, under an Ar atmosphere, heating at 2°C for 2 minutes. -1 The heating rate is maintained at 300-400℃ for 1-2 hours.

[0018] Further, in step 4), the amount of 2-methylimidazole used is 0.7-0.9g, the ratio of anhydrous ethanol to deionized water is 1:1, the ultrasonic time is 8-15min, and the ultrasonic frequency is 20-40KHz.

[0019] Further, in step 5), the amount of thioacetamide used is 0.02-0.04g, and the amount of anhydrous ethanol is 20-40mL.

[0020] Further, the washing and drying steps described in steps 3), 4), and 6) involve washing with anhydrous ethanol and deionized water in sequence, followed by drying in a vacuum drying oven at 50°C for 7-9 hours.

[0021] Furthermore, in step 7), the electrochemical performance test adopts a three-electrode system, with a platinum sheet as the counter electrode, a Co9S8@CoO-NF composite material as the working electrode, a calomel electrode as the reference electrode, and a 6 mol / L KOH electrolyte.

[0022] This invention provides a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO, which is prepared by the above-mentioned method for preparing the hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO.

[0023] This invention provides the application of the hollow Co9S8 composite material derived from ZIF-67 grown in situ on the above-mentioned rod-shaped radial cluster CoO as an electrode material in supercapacitors.

[0024] The beneficial effects of this invention are: the hollow Co9S8 composite material derived from ZIF-67 grown in situ on rod-shaped radial clusters CoO prepared by this invention can have good application value and prospects in the field of supercapacitor electrode materials. This invention employs a hydration-carbonization-in-situ growth-sulfurization method to prepare a 3D hollow rod-shaped radial cluster composite electrode material. Using CoO with a rod-shaped radial cluster structure as the substrate facilitates electrolyte penetration. The in-situ growth of ZIF-67 on CoO is carried out at room temperature, making the preparation process simple and easy to implement. ZIF-67 serves as a template for constructing hollow Co9S8, retaining its excellent pore structure and large specific surface area. Sulfurization transforms ZIF-67 into hollow Co9S8. The formation of the hollow structure increases the contact area between the electrolyte and the electrode material, improving the stability of the electrode material. The effective synergy of the Co9S8@CoO heterostructure promotes electron transport, effectively enhancing the energy storage capacity of supercapacitors. This preparation process of ZIF-67-derived hollow Co9S8 composite material grown in situ on rod-shaped radial cluster CoO is simple, easy to implement experimentally, and has low synthesis costs, demonstrating great application potential. It can provide technical support for the preparation of high-stability, high-energy storage electrode materials for supercapacitors. Attached Figure Description

[0025] Figure 1 a is a scanning electron microscope (SEM) image of Co(OH)F-NF in Example 1;

[0026] Figure 1 b is a scanning electron microscope (SEM) image of CoO-NF in Example 1;

[0027] Figure 1 c is a scanning electron microscope (SEM) image of ZIF-67@CoO-NF in Example 1;

[0028] Figure 1 d, e, and f are scanning electron microscope (SEM) images of Co9S8@CoO-NF in Example 1;

[0029] Figure 2 a is the XRD pattern of CoO-NF and ZIF-67@CoO-NF in Example 1;

[0030] Figure 2 b is the XRD pattern of Co9S8@CoO-NF in Example 1;

[0031] Figure 3 a represents CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF from Example 1 at a scan rate of 3 mV / s. -1 The CV curve;

[0032] Figure 3 b represents the CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF from Example 1 at a current density of 5 mA cm⁻¹. -2 The GCD curve;

[0033] Figure 3 c is the Nyquist curve of CoO-NF, ZIF-67@CoO-NF and Co9S8@CoO-NF in Example 1.

[0034] Figure 4 a is the Co9S8@CoO-NF from Example 1 at scan rates of 1–9 mV / s -1 The CV curve;

[0035] Figure 4 b is the Co9S8@CoO-NF from Example 1 at a current density of 5–30 mA cm⁻¹ -2 The GCD curve. Detailed Implementation

[0036] In the description of this invention, it should be noted that unless specific conditions are specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] Example 1

[0038] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0039] 1) Cut the nickel foam (NF) into pieces of 1×1.5cm. Place the NF in a beaker containing 20mL of acetone and sonicate at room temperature for 15min at a frequency of 40KHz. Then transfer the NF to 20mL of anhydrous ethanol and sonicate at room temperature for 15min. Finally, transfer the NF to 20mL of deionized water and maintain it in the sonic environment for 15min. Remove the NF and dry it in an oven at 50℃ for 8h.

[0040] 2) Dissolve Co(NO3)2·6H2O (0.3g, 0.1mmol), NH4F (0.15g, 4mmol), and CH4N2O (0.3g, 5mmol) in 20mL of deionized water. Pour the mixed solution into a 100mL reaction vessel and stir at room temperature for 5min to obtain a pink mixed solution, which is then poured into the reaction vessel.

[0041] 3) Immerse the treated nickel foam (NF) in the above mixed solution and maintain it at 120°C for 9 hours. After washing with anhydrous ethanol and deionized water, dry it in an oven at 50°C for 8 hours. Then, place the precursor into a ceramic boat and transfer it into a tube furnace at 2°C for 1 minute.-1 The precursor rod-shaped radial cluster CoO-NF was prepared by heating at 350℃ for 1 hour.

[0042] 4) 0.82 g of 2-methylimidazole as an organic ligand was placed in a mixture of ethanol (2.5 mL) and deionized water (2.5 mL), and sonicated at room temperature for 10 min at a frequency of 40 kHz. The CoO-NF precursor was then added, and the mixture was allowed to stand at room temperature for 24 h. After washing with anhydrous ethanol and deionized water, the mixture was dried in an oven at 50 ℃ for 8 h to obtain the precursor ZIF-67@CoO-NF.

[0043] 5) Sonicate 0.03g of thioacetamide (CH3CSNH2) and 30mL of anhydrous ethanol at room temperature for 5min until the thioacetamide dissolves. The sonication frequency is 40KHz. Prepare a mixed solution and pour the mixed solution into a 100mL reaction vessel.

[0044] 6) The ZIF-67@CoO-NF precursor was placed at the bottom of the reactor and kept at 120°C for 4 hours. It was then washed with anhydrous ethanol and deionized water and dried in an oven at 50°C for 8 hours to obtain the target product, hollow rod-shaped radial cluster Co9S8@CoO-NF.

[0045] Example 2

[0046] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0047] 1) Cut the nickel foam (NF) into pieces of 1×1.5cm. Place the NF in a beaker containing 20mL of acetone and sonicate at room temperature for 15min at a frequency of 40KHz. Then transfer the NF to 20mL of anhydrous ethanol and sonicate at room temperature for 15min. Finally, transfer the NF to 20mL of deionized water and maintain it in the sonic environment for 15min. Remove the NF and dry it in an oven at 50℃ for 8h.

[0048] 2) Dissolve Co(NO3)2·6H2O (0.4g, 0.1mmol), NH4F (0.2g, 4mmol), and CH4N2O (0.4g, 5mmol) in 30mL of deionized water. Pour the mixed solution into a 100mL reaction vessel and stir at room temperature for 5min to obtain a pink mixed solution, which is then poured into the reaction vessel.

[0049] 3) Immerse the treated nickel foam (NF) in the above mixed solution and maintain at 140°C for 9 hours. Wash with anhydrous ethanol and deionized water, dry in an oven at 50°C for 8 hours, then place the precursor into a ceramic boat and transfer it to a tube furnace at 2°C for 1 minute. -1 The precursor rod-shaped radial cluster CoO-NF was prepared by heating at 350℃ for 2 hours.

[0050] 4) 0.86 g of 2-methylimidazole as an organic ligand was placed in a mixture of ethanol (5 mL) and deionized water (5 mL), and sonicated at room temperature for 10 min at a frequency of 40 kHz. The CoO-NF precursor was then placed in the mixture, and the mixture was allowed to stand at room temperature for 24 h. After washing with anhydrous ethanol and deionized water, the mixture was dried in an oven at 50 ℃ for 8 h to obtain the precursor ZIF-67@CoO-NF.

[0051] 5) Sonicate 0.03g of thioacetamide (CH3CSNH2) and 30mL of anhydrous ethanol at room temperature for 5min until the thioacetamide dissolves. The sonication frequency is 40KHz. Prepare a mixed solution and pour the mixed solution into a 100mL reaction vessel.

[0052] 6) The ZIF-67@CoO-NF precursor was placed at the bottom of the reactor and kept at 120°C for 4 hours. It was then washed with anhydrous ethanol and deionized water and dried in an oven at 50°C for 8 hours to obtain the target product, hollow rod-shaped radial cluster Co9S8@CoO-NF.

[0053] Example 3

[0054] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0055] 1) Cut the nickel foam (NF) into pieces of 1×1.5cm. Place the NF in a beaker containing 20mL of acetone and sonicate at room temperature for 15min at a frequency of 40KHz. Then transfer the NF to 20mL of anhydrous ethanol and sonicate at room temperature for 15min. Finally, transfer the NF to 30mL of deionized water and maintain it in the sonic environment for 15min. Remove the NF and dry it in an oven at 50℃ for 8h.

[0056] 2) Dissolve Co(NO3)2·6H2O (0.4g, 0.2mmol), NH4F (0.2g, 8mmol), and CH4N2O (0.4g, 10mmol) in 30mL of deionized water. Pour the mixed solution into a 100mL reaction vessel and stir at room temperature for 5min to obtain a pink mixed solution, which is then poured into the reaction vessel.

[0057] 3) Immerse the treated nickel foam (NF) in the above mixed solution and maintain it at 150°C for 9 hours. Wash with anhydrous ethanol and deionized water, dry in an oven at 50°C for 8 hours, then place the precursor into a ceramic boat and transfer it to a tube furnace at 2°C for 1 minute. -1 The precursor rod-shaped radial cluster CoO-NF was prepared by heating at 400℃ for 2 hours.

[0058] 4) 0.90 g of 2-methylimidazole as an organic ligand was placed in a mixture of ethanol (5 mL) and deionized water (5 mL), and sonicated at room temperature for 15 min at a frequency of 40 kHz. The CoO-NF precursor was then placed in the mixture, and the mixture was allowed to stand at room temperature for 24 h. After washing with anhydrous ethanol and deionized water, the mixture was dried in an oven at 50 °C for 8 h to obtain the precursor ZIF-67@CoO-NF.

[0059] 5) Sonicate 0.04g of thioacetamide (CH3CSNH2) and 40mL of anhydrous ethanol at room temperature for 10min until the thioacetamide dissolves. The sonication frequency is 40KHz. Prepare a mixed solution and pour the mixed solution into a 100mL reaction vessel.

[0060] 6) The ZIF-67@CoO-NF precursor was placed at the bottom of the reactor and kept at 150°C for 4 hours. It was then washed with anhydrous ethanol and deionized water and dried in an oven at 50°C for 8 hours to obtain the target product, hollow rod-shaped radial cluster Co9S8@CoO-NF.

[0061] Example 4

[0062] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0063] 1) Cut the nickel foam (NF) into pieces of 1×1.5cm. Place the NF in a beaker containing 20mL of acetone and sonicate at room temperature for 15min at a frequency of 40KHz. Then transfer the NF to 20mL of anhydrous ethanol and sonicate at room temperature for 15min. Finally, transfer the NF to 20mL of deionized water and maintain it in the sonic environment for 15min. Remove the NF and dry it in an oven at 50℃ for 8h.

[0064] 2) Dissolve Co(NO3)2·6H2O (0.3g, 0.2mmol), NH4F (0.15g, 8mmol), and CH4N2O (0.3g, 10mmol) in 20mL of deionized water. Pour the mixed solution into a 100mL reaction vessel and stir at room temperature for 5min to obtain a pink mixed solution, which is then poured into the reaction vessel.

[0065] 3) Immerse the treated nickel foam (NF) in the above mixed solution and maintain at 120°C for 9 hours. Wash with anhydrous ethanol and deionized water, dry in an oven at 50°C for 8 hours, then place the precursor into a ceramic boat and transfer it to a tube furnace at 2°C for 1 minute. -1 The precursor rod-shaped radial cluster CoO-NF was prepared by heating at 350℃ for 1 hour.

[0066] 4) 0.8 g of 2-methylimidazole as an organic ligand was placed in a mixture of ethanol (2.5 mL) and deionized water (2.5 mL), and sonicated at room temperature for 8 min at a frequency of 40 kHz. The CoO-NF precursor was then added and allowed to stand at room temperature for 24 h. The mixture was then washed with anhydrous ethanol and deionized water and dried in an oven at 50 °C for 8 h to obtain the precursor ZIF-67@CoO-NF.

[0067] 5) Sonicate 0.03g of thioacetamide (CH3CSNH2) and 20mL of anhydrous ethanol at room temperature for 5min until the thioacetamide dissolves. The sonication frequency is 40KHz. Prepare a mixed solution and pour the mixed solution into a 100mL reaction vessel.

[0068] 6) The ZIF-67@CoO-NF precursor was placed at the bottom of the reactor and kept at 140℃ for 5 hours. It was then washed with anhydrous ethanol and deionized water and dried in an oven at 50℃ for 8 hours to obtain the target product, hollow rod-shaped radial cluster Co9S8@CoO-NF.

[0069] Example 5

[0070] A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO includes the following steps:

[0071] 1) Cut the nickel foam (NF) into pieces of 1×1.5cm. Place the NF in a beaker containing 20mL of acetone and sonicate at room temperature for 15min at a frequency of 40KHz. Then transfer the NF to 20mL of anhydrous ethanol and sonicate at room temperature for 15min. Finally, transfer the NF to 20mL of deionized water and maintain it in the sonic environment for 15min. Remove the NF and dry it in an oven at 50℃ for 8h.

[0072] 2) Dissolve Co(NO3)2·6H2O (0.2g, 0.2mmol), NH4F (0.1g, 8mmol), and CH4N2O (0.2g, 10mmol) in 10mL of deionized water. Pour the mixed solution into a 100mL reaction vessel and stir at room temperature for 5min to obtain a pink mixed solution, which is then poured into the reaction vessel.

[0073] 3) Immerse the treated nickel foam (NF) in the above mixed solution and maintain it at 100°C for 8 hours. Wash with anhydrous ethanol and deionized water, dry in an oven at 50°C for 8 hours, then place the precursor into a ceramic boat and transfer it to a tube furnace at 2°C for 1 minute. -1 The precursor rod-shaped radial cluster CoO-NF was prepared by heating at 350℃ for 2 hours.

[0074] 4) 0.70 g of 2-methylimidazole as an organic ligand was placed in a mixture of ethanol (2.5 mL) and deionized water (2.5 mL), and sonicated at room temperature for 10 min at a frequency of 20 kHz. The CoO-NF precursor was then added and allowed to stand at room temperature for 24 h. After washing with anhydrous ethanol and deionized water, the precursor ZIF-67@CoO-NF was obtained by drying in an oven at 50 °C for 8 h.

[0075] 5) Sonicate 0.02g of thioacetamide (CH3CSNH2) and 20mL of anhydrous ethanol at room temperature for 5min until the thioacetamide dissolves. The sonication frequency is 20KHz. Prepare a mixed solution and pour the mixed solution into a 100mL reaction vessel.

[0076] 6) Place the ZIF-67@CoO-NF precursor at the bottom of the reactor and keep it at 150℃ for 3 hours. Wash it with anhydrous ethanol and deionized water and dry it in an oven at 50℃ for 8 hours to obtain the target product, hollow rod-shaped radial cluster Co9S8@CoO-NF.

[0077] The test results of the hollow Co9S8 composite material derived from ZIF-67 grown in situ on CoO prepared in Example 1 are as follows:

[0078] Figure 1 The results of scanning electron microscopy (SEM) analysis of the in-situ grown ZIF-67-derived hollow Co9S8 composite material on rod-shaped radial clusters prepared in Example 1 of this invention are shown. In this study, Co(OH)F-NF exhibits a rod-shaped radial cluster structure with a diameter of 10 μm, uniformly grown on NF. Figure 1 (a)). After carbonization treatment, CoO-NF, which is then processed, still maintains the rod-shaped radial cluster structure, and no damage to the rod-shaped radial cluster structure was observed, indicating that the structure has a certain degree of stability. Figure 1 (b) Following a coordination reaction, ZIF-67 was grown in situ on CoO-NF. ZIF-67 grew uniformly on CoO without aggregation, maintaining its radial structure. Figure 1 (c)). From Figure 1 (e) It can be observed that after vulcanization, the surface of Co9S8@CoO-NF becomes rough, indicating that vulcanization has an effect on ZIF-67@CoO-NF. Meanwhile, Co9S8@CoO-NF still maintains a rod-shaped radial cluster structure. Most importantly, there is no detachment of Co9S8@CoO from the NF, indicating that Co9S8@CoO has a certain adhesion to the NF. Figure 1 (d) and (f).

[0079] Figure 2 The XRD patterns of CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF in Example 1 are shown below. Figure 2 (a) The three peaks at 2θ of 44.49°, 51.84°, and 76.37° are characteristic peaks of NF. After carbonization of Co(OH)F-NF, obvious characteristic peaks of CoO (PDF#65-2902) are observed at 2θ of 36.50°, 42.39°, and 61.51°. After coordination reaction with 2-methylimidazole, diffraction peaks of ZIF-67 appear. In addition, the intensity of the diffraction peak of CoO is weakened, which is attributed to the coating of ZIF-67 on CoO, such as... Figure 2 (a).

[0080] After vulcanization, ZIF-67@CoO-NF exhibited characteristic peaks of Co9S8 (PDF#65-1765), such as... Figure 2 (b) Meanwhile, the presence of characteristic peaks of CoO indicates the coexistence of Co9S8 and CoO, and confirms the successful preparation of hollow rod-shaped radioactive clusters Co9S8@CoO-NF.

[0081] Figure 3 (a) The results of scanning tests on CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF in Example 1 at a scan rate of 3 mV / s. -1 The CV curves of the three electrode materials are shown in the figure. It can be observed that the CV curves of all three electrode materials exhibit a pair of redox peaks, indicating the presence of a redox reaction during the electrochemical process, thus proving that all three electrode materials are pseudocapacitive materials. Pseudocapacitive materials can achieve high capacitance performance due to their rapid and reversible redox reactions. At the same scan rate, compared with the CV curve areas of CoO-NF and ZIF-67@CoO-NF, Co9S8@CoO-NF exhibits a larger CV area, indicating the high capacitance of Co9S8@CoO-NF.

[0082] Figure 3 (b) The CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF in Example 1 at a current density of 5 mA cm⁻¹ -2 The GCD curves are shown in the figure. As can be seen from the figure, the charge-discharge curves exhibit a pair of charge-discharge plateaus, consistent with the CV test results. Compared with the discharge times of CoO-NF and ZIF-67@CoO-NF, Co9S8@CoO-NF exhibits the longest discharge time, further indicating that it possesses the best capacitance performance. According to the GCD results, the areal capacitance of Co9S8@CoO-NF is higher than that of CoO-NF and ZIF-67@CoO-NF, indicating that Co9S8@CoO-NF has superior electrochemical performance.

[0083] Figure 3(c) Nyquist curves of CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF in Example 1. (The text then abruptly shifts to a different topic: "and CoO-NF(R...") ct =2.29Ω) and ZIF-67@CoO-NF(R ct =1.02Ω) compared to Co9S8@CoO-NF, R ct The lowest value (0.39Ω) indicates a fast charge transfer rate, further confirming that the introduction of sulfur improves the electron transport efficiency of the material. The internal resistances of CoO-NF, ZIF-67@CoO-NF, and Co9S8@CoO-NF are 1.26, 0.82, and 0.60Ω, respectively. This can be explained by the fact that the hollow structure formed after sulfurization reduces its own impedance and interfacial impedance, and facilitates electrolyte ion diffusion. The test results are consistent with CV and GCD, indicating that the hollow structure and components of Co9S8@CoO-NF can effectively synergize to achieve high electrochemical performance.

[0084] Figure 4 (a) Electrochemical performance of Co9S8@CoO-NF in Example 1, at scan rates of 1–9 mV s. -1 The CV performance was then tested. As shown in the figure, the area under the CV curve increases with increasing scan rate, but the redox peaks still exist, indicating that Co9S8@CoO-NF has good rate performance. With increasing scan rate, the response current of Co9S8@CoO-NF gradually increases, but due to the fast scan rate and short reaction time, electrolyte ions cannot diffuse into the electrode material to participate in the redox reaction in a short time. The oxidation and reduction peaks shift towards opposite ends of the coordinate axis, which is a typical characteristic of pseudocapacitive materials.

[0085] Figure 4 (b) The Co9S8@CoO-NF in Example 1 at a current density of 5–30 mA cm⁻¹ -2 The GCD performance was analyzed. As shown in the figure, the GCD curve exhibits a clear charge-discharge plateau. Furthermore, the GCD curve demonstrates good symmetry, indicating that Co9S8@CoO-NF possesses excellent electrochemical reversibility. Based on the GCD test results, the GCD performance was analyzed at current densities of 5, 10, 15, 20, 25, and 30 mA / cm². -2 The areal capacitances are 18.13 F cm⁻¹. -2 (2952F g -1 ), 17.58F cm -2 (2895F g -1 ), 17.18F cm -2 (2794F g -1 ), 16.44F cm -2 (2698F g-1 ), 15.95F cm -2 (2627F g -1 ) and 15.52F cm -2 (2557F g -1 When the current density is 30 mA cm⁻¹ -2 At that time, the capacitance retention rate of Co9S8@CoO-NF was 85.59%, which is due to the fact that the hollow structure facilitates the diffusion of electrolyte ions and can effectively alleviate volume changes and promote stress release during the electrochemical process.

Claims

1. A method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO, characterized in that, Includes the following steps: 1) Pre-treat the nickel foam NF; 2) Mix Co(NO3)2·6H2O, NH4F, CH4N2O and deionized water, stir at room temperature for 5-10 min to obtain a pink mixed solution, and pour it into a reaction vessel; 3) Immerse the treated nickel foam NF in the above mixed solution, keep it at 100-150℃ for 8-10 hours, take out the NF, wash and dry it, and then carbonize it to obtain the CoO-NF precursor. 4) Dissolve 2-methylimidazole in a mixed solution of anhydrous ethanol and deionized water, sonicate at room temperature until dissolved, add CoO-NF precursor, let stand at room temperature for 22-25 h, wash and dry to obtain ZIF-67@CoO-NF precursor; 5) Sonicate thioacetamide (CH3CSNH2) and anhydrous ethanol at room temperature for 3-10 minutes until the thioacetamide dissolves to obtain a mixed solution, and pour it into a reaction vessel; 6) Place the ZIF-67@CoO-NF precursor into a reactor, keep it at 100-150℃ for 3-5 hours, let it stand to room temperature, wash and dry to obtain the target product Co9S8@CoO-NF; 7) Electrochemical performance tests were performed on the target product Co9S8@CoO-NF.

2. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 1), the pretreatment method of NF is as follows: First, cut NF into pieces of size 1×1.5cm, then place NF in acetone, anhydrous ethanol and deionized water in sequence and sonicate for 10-30min respectively, with a sonication frequency of 20-40KHz. After taking it out, dry it in a vacuum drying oven at 50°C for 7-9h.

3. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 2), the mass ratio of Co(NO3)2·6H2O, NH4F and CH4N2O is 2:1:2, and the amount of deionized water is 10-30 mL.

4. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 3), the carbonization step involves transferring the treated NF into a tube furnace and, under an Ar atmosphere, carbonizing at 2°C for 2 minutes. -1 The heating rate is maintained at 300-400℃ for 1-2 hours.

5. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 4), the amount of 2-methylimidazole used is 0.7-0.9g, the ratio of anhydrous ethanol to deionized water is 1:1, the ultrasonic time is 8-15 min, and the ultrasonic frequency is 20-40KHz.

6. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 5), the amount of thioacetamide used is 0.02-0.04g, and the amount of anhydrous ethanol is 20-40mL.

7. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, The washing and drying steps described in steps 3), 4), and 6) involve washing the product sequentially with anhydrous ethanol and deionized water, followed by drying it in a 50°C vacuum drying oven for 7-9 hours.

8. The method for preparing a hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO according to claim 1, characterized in that, In step 7), the electrochemical performance test uses a three-electrode system. The counter electrode is a platinum sheet, the working electrode is a Co9S8@CoO-NF composite material, the reference electrode is a calomel electrode, and the electrolyte is 6 mol / L KOH.

9. A hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster of CoO, characterized in that, The composite material, ZIF-67-derived hollow Co9S8, was prepared by the method described in any one of claims 1-8, for in-situ growth on a rod-shaped radial cluster CoO.

10. The application of the hollow Co9S8 composite material derived from ZIF-67 grown in situ on a rod-shaped radial cluster CoO as described in claim 9 as an electrode material in a supercapacitor.

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