Preparation and application of molybdenum-doped cobalt hydroxide carbonate nanosheet@cobalt sulfide nanosheet array / foam nickel composite

Abstract

This invention discloses a method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material as a supercapacitor electrode material. The purpose of this invention is to carefully design a core-shell structure composed of different components to improve the specific capacity and cycle performance of the electrode material. This invention mainly includes: 1. Hydrothermal synthesis to prepare cobalt-metal-organic framework / nickel foam (Co-MOF / NF); 2. Hydrothermal sulfidation to prepare cobalt sulfide nanosheet array / nickel foam (Co3S4 / NF); 3. Hydrothermal preparation of molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam (Mo-CCH@Co3S4 / NF). This invention features a simple synthesis process, low cost, high yield, and no need for subsequent processing. The Mo-CCH@Co3S4 / NF heterostructure exhibits excellent electrical conductivity and stronger OH- ions. ‑ The Mo-CCH@Co3S4 / NF electrode exhibits enhanced capture capability, thereby improving the efficiency of rapid redox processes. At 1 A g... ‑1 It was 1816.2 C g at that time. ‑1 The specific capacitance at 10 A g ‑1 It exhibits excellent cycling performance of 87.5% over 10,000 cycles.

Description

Technical Field

[0001] This invention relates to the fields of materials preparation and energy storage, and more specifically, to a method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material as a supercapacitor electrode material. Background Technology

[0002] In recent years, severe environmental problems have driven a global consensus on the urgent need to develop renewable energy storage technologies. Supercapacitors, with their ultra-fast charging and discharging rates and ultra-high power density, have become energy storage devices with great development potential.

[0003] Co3S4, with its high specific capacity, excellent conductivity, and tunable structure, is an ideal candidate material for high-performance hybrid supercapacitor electrodes. Co3S4 nanosheet arrays derived from MOFs possess abundant porosity and a large specific surface area, providing numerous electrochemical active sites while enhancing the interfacial interaction between electrolyte ions and electrode materials. Furthermore, the nanosheet array structure provides unobstructed diffusion channels for the rapid transport of ions and electrons.

[0004] Core-shell structures can optimize electron / ion transport pathways, synergistically improve specific capacity, and simultaneously suppress active material aggregation and structural collapse, thereby enhancing cycling stability. Furthermore, core-shell structures can shorten charge migration distances, accelerate interfacial charge transfer kinetics, and strengthen synergistic effects between different components, ultimately improving overall electrochemical performance.

[0005] Currently, metal oxides, metal sulfides, and metal hydroxides are often used with MOF-derived Co3S4 nanosheet arrays to construct core-shell composite materials, which can significantly improve electrochemical performance. Basic cobalt carbonate (CCH) contains abundant redox active sites and has a significant theoretical specific capacity advantage; at the same time, the carbonate ion can play a structural stabilizing role, effectively improving the electrode cycle life. Mo doping can significantly improve the inherent poor conductivity of basic carbonates and reduce charge transfer resistance, thereby greatly improving the conductivity of basic cobalt carbonate. Therefore, in-situ growth of Mo-doped CCH nanosheets on the surface of Co3S4 nanosheet arrays and construction of a core-shell structure can combine the dual advantages of Mo-CCH's abundant active sites and excellent conductivity, and utilize the buffering effect of the composite structure to suppress volume deformation during charge and discharge, which is expected to simultaneously achieve a synergistic improvement in electrode specific capacity and cycle stability.

[0006] In summary, this invention has prepared a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material. Due to its core-shell structure and the synergistic effect between the multi-component metals, it has excellent electrochemical performance and has good application prospects as an electrode material for supercapacitors. Summary of the Invention

[0007] The purpose of this invention is to improve the electrochemical performance of electrode materials by carefully designing core-shell structures composed of different components, and to provide a method for preparing molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet arrays / nickel foam supercapacitor electrode materials.

[0008] The preparation method of the molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material of the present invention is carried out according to the following steps:

[0009] I. Preparation of Cobalt-Metal-Organic Framework / Nickel Foam (Co-MOF / NF) by Hydrothermal Synthesis

[0010] 0.58–1.74 g of cobalt nitrate hexahydrate and 1.32–3.96 g of 2-methylimidazole were each dissolved in 40 mL of deionized water. Nickel foam was then placed in the above mixed solution and allowed to stand at room temperature for 4–6 hours. After three washes and drying, cobalt-metal-organic framework / nickel foam (Co-MOF / NF) was finally obtained.

[0011] II. Preparation of Cobalt Sulfide Nanosheet Arrays / Nickel Foam (Co3S4 / NF) by Hydrothermal Sulfidation

[0012] Add 90-180 mg of thioacetamide to 30 mL of ethanol, stir for 30 min, transfer to a high-pressure reactor, then add Co-MOF / NF, and react at 120-160 °C for 4-6 h to finally obtain cobalt sulfide nanosheet array / nickel foam (Co3S4 / NF).

[0013] III. Hydrothermal Preparation of Molybdenum-Doped Basic Cobalt Carbonate Nanosheets@Cobalt Sulfide Nanosheet Array / Nickel Foam (Mo-CCH@Co3S4 / NF)

[0014] 0.25–1 mmol cobalt nitrate hexahydrate, 0.025–0.1 mmol sodium molybdate dihydrate, and 1.25–5 mmol urea were added to 30 mL of deionized water. The mixture was then transferred to a 50 mL high-pressure reactor, and Co3S4 / NF was added. The mixture was then subjected to a hydrothermal reaction at 120–160 °C for 4–8 h to obtain the composite material Mo-CCH@Co3S4 / NF.

[0015] Compared with existing technologies, the present invention has the following advantages:

[0016] (1) In this invention, Mo-CCH nanosheets are integrated on a Co3S4 nanosheet array, which will make full use of the synergistic effect of Mo-CCH nanosheets with excellent redox activity and Co3S4 nanosheet array with high conductivity, and significantly improve the electrochemical performance of supercapacitors.

[0017] (2) The molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material prepared by the present invention has a core-shell structure that enhances the contact area between the electrolyte and the electrode, provides more channels for the diffusion of the electrolyte, shortens the ion transfer path and accelerates the electron transfer, and ensures good conductivity and cycle stability of the electrode. Attached Figure Description

[0018] Figure 1 A schematic diagram illustrating the synthesis of a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material;

[0019] Figure 2 This is a morphology photograph of a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material.

[0020] Figure 3 The crystal structure and chemical composition of a molybdenum-doped basic cobalt carbonate nanosheet@cobalt sulfide nanosheet array / nickel foam composite material are prepared.

[0021] Figure 4 The electrochemical properties of a molybdenum-doped basic cobalt carbonate nanosheet@cobalt sulfide nanosheet array / nickel foam composite material are described.

[0022] Figure 5 This is a density functional theory calculation diagram of a molybdenum-doped basic cobalt carbonate nanosheet@cobalt sulfide nanosheet array / nickel foam composite material.

[0023] Figure 6 The morphology of a molybdenum-doped basic cobalt carbonate nanosheet@cobalt sulfide nanosheet array / nickel foam composite material is shown. Detailed Implementation

[0024] Specific Implementation Method 1: A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material, specifically carried out according to the following steps:

[0025] I. Preparation of Cobalt-Metal-Organic Framework / Nickel Foam (Co-MOF / NF) by Hydrothermal Synthesis

[0026] 0.58–1.74 g of cobalt nitrate hexahydrate and 1.32–3.96 g of 2-methylimidazole were each dissolved in 40 mL of deionized water. Nickel foam was then placed in the above mixed solution and allowed to stand at room temperature for 4–6 hours. After three washes and drying, cobalt-metal-organic framework / nickel foam (Co-MOF / NF) was finally obtained.

[0027] II. Preparation of Cobalt Sulfide Nanosheet Arrays / Nickel Foam (Co3S4 / NF) by Hydrothermal Sulfidation

[0028] Add 90-180 mg of thioacetamide to 30 mL of ethanol, stir for 30 min, transfer to a high-pressure reactor, then add Co-MOF / NF, and react at 120-160 °C for 4-6 h to finally obtain cobalt sulfide nanosheet array / nickel foam (Co3S4 / NF).

[0029] III. Hydrothermal Preparation of Molybdenum-Doped Basic Cobalt Carbonate Nanosheets@Cobalt Sulfide Nanosheet Array / Nickel Foam (Mo-CCH@Co3S4 / NF)

[0030] 0.25–1 mmol cobalt nitrate hexahydrate, 0.025–0.1 mmol sodium molybdate dihydrate, and 1.25–5 mmol urea were added to 30 mL of deionized water. The mixture was then transferred to a 50 mL high-pressure reactor, and Co3S4 / NF was added. The mixture was then subjected to a hydrothermal reaction at 120–160 °C for 4–8 h to obtain the composite material Mo-CCH@Co3S4 / NF.

[0031] Specific Implementation Method Two: A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material, specifically carried out according to the following steps:

[0032] The difference between this embodiment and Specific Embodiment 1 is that the content of cobalt nitrate hexahydrate in the preparation of Co-MOF / NF in step one is 0.58~1.16 g. Everything else is the same as in Specific Embodiment 1.

[0033] Specific Implementation Method 3: A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material, specifically carried out according to the following steps:

[0034] The difference between this embodiment and specific embodiments one and two is that the content of thioacetamide in step two is 90-150 mg. Everything else is the same as specific embodiments one and two.

[0035] Specific Implementation Method Four: A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material, specifically carried out according to the following steps:

[0036] The difference between this embodiment and specific embodiments one to three is that the hydrothermal time for preparing Mo-CCH@Co3S4 / NF in step three is 6-8 hours. Everything else is the same as in specific embodiments one to three.

[0037] The effectiveness of the present invention was verified by the following experiments:

[0038] This experiment describes a method for preparing a molybdenum-doped basic cobalt carbonate nanosheet@cobalt sulfide nanosheet array / nickel foam supercapacitor electrode material, specifically carried out according to the following steps:

[0039] I. Preparation of Cobalt-Metal-Organic Framework / Nickel Foam (Co-MOF / NF) by Hydrothermal Synthesis

[0040] 0.58 g of cobalt nitrate hexahydrate and 1.32 g of 2-methylimidazole were each dissolved in 40 mL of deionized water. Nickel foam was placed in the above mixed solution and allowed to stand at room temperature for 4 hours. After rinsing three times and drying, cobalt-metal-organic framework / nickel foam (Co-MOF / NF) was finally obtained.

[0041] II. Preparation of Cobalt Sulfide Nanosheet Arrays / Nickel Foam (Co3S4 / NF) by Hydrothermal Sulfidation

[0042] 90 mg of thioacetamide was added to 30 mL of ethanol, stirred for 30 min, and then transferred to a high-pressure reactor. Co-MOF / NF was then added and reacted at 120 °C for 4 h to finally obtain cobalt sulfide nanosheet array / nickel foam (Co3S4 / NF).

[0043] III. Hydrothermal Preparation of Molybdenum-Doped Basic Cobalt Carbonate Nanosheets@Cobalt Sulfide Nanosheet Array / Nickel Foam (Mo-CCH@Co3S4 / NF)

[0044] 0.25 mmol cobalt nitrate hexahydrate, 0.025 mmol sodium molybdate dihydrate and 1.25 mmol urea were added to 30 mL of deionized water. The mixed solution was transferred to a 50 mL high-pressure reactor, and Co3S4 / NF was added. The mixture was hydrothermally reacted at 120 °C for 6 h to obtain the composite material Mo-CCH@Co3S4 / NF.

[0045] This invention uses a three-electrode testing system to study the electrochemical performance of materials. A platinum sheet is used as the counter electrode, a saturated Hg / HgO electrode as the reference electrode, and Mo-CCH@Co3S4 / NF as the working electrode. Electrochemical detection is performed under the condition of 6 M potassium hydroxide solution as the electrolyte.

[0046] Figure 1This diagram illustrates the synthesis of Mo-CCH@Co3S4 / NF nanosheet arrays / nickel foam. First, nickel foam was placed in a mixed solution of cobalt nitrate hexahydrate and 2-methylimidazole, and a triangular Co-MOF nanosheet array was grown on the surface of the nickel foam through a room-temperature co-precipitation reaction. Subsequently, Co-MOF / NF was added to an ethanol solution containing thioacetamide, and subjected to solvothermal vulcanization to obtain MOF-derived Co3S4 nanosheet arrays / nickel foam. Finally, Co3S4 / NF was placed in a mixed solution containing cobalt nitrate hexahydrate, sodium molybdate dihydrate, and urea for a hydrothermal reaction, ultimately preparing a core-shell structured Mo-CCH@Co3S4 / NF composite material.

[0047] Figure 2 The microstructure of Mo-CCH@Co3S4 / NF is shown. Triangular sheet-like Co-MOF nanosheets grow vertically and uniformly on the surface of nickel foam substrate, with a regular and dense arrangement, and the nanosheet surface is smooth and flat. Figure 2 a). After solvothermal sulfidation, the obtained Co3S4 basically retains the triangular lamellar morphology of Co-MOF, with the lamellar edges curling inward and the surface roughness significantly improved. Figure 2 b). Mo-CCH nanosheets can be vertically interwoven and grown on the surface of Co3S4 / NF substrates, successfully constructing a core-shell nanostructure Mo-CCH@Co3S4 / NF. Figure 2 c). EDS elemental mapping results for Mo-CCH@Co3S4 / NF show that Ni, Co, Mo, C, O, and S elements are uniformly distributed within the material. Figure 2 d). TEM characterization confirmed that the material has a clear core-shell structure, with the inner Co3S4 / NF nanosheets uniformly coated by the outer Mo-CCH nanosheets. Figure 2 e). Figure 2 f is the HRTEM image of the sample, and the inset is the inverse fast Fourier transform (IFFT) spectrum of the corresponding region, where the lattice fringes with a lattice spacing of 0.264 nm and 0.245 nm correspond to the (221) and (301) crystal planes of basic cobalt carbonate (CCH), respectively. Figure 2 The SAED diffraction rings of g can be attributed to the (023) and (301) crystal planes of CCH, respectively.

[0048] Figure 3 The crystal structure, functional groups, chemical composition, and elemental valence states of Mo-CCH@Co3S4 / NF were characterized. Figure 3In diagram a, the diffraction peaks at 26.6°, 31.4°, 38.1°, 47.3°, 50.2°, and 55.2° correspond to the (220), (311), (400), (422), (511), and (440) crystal planes of Co3S4 / NF, respectively (PDF#00-042-1448). Furthermore, the diffraction peaks at 44.5°, 51.7°, and 76.4° are attributed to the (111), (200), and (220) crystal planes of nickel foam. After growing Mo-CCH on the surface of Co3S4 / NF nanosheet array, the sample showed new diffraction peaks at 19.3°, 26.3°, 29.6°, 33.1°, 36.5°, 38.7°, 46.5° and 62.5°, corresponding to the (001), (220), (300), (221), (301), (231), (340) and (450) crystal planes of basic cobalt carbonate (Co2CO3(OH)2, PDF: #00-048-0083). Figure 3 b represents the Fourier transform infrared (FT-IR) spectrum of Mo-CCH@Co3S4 / NF. The value at 3422 cm⁻¹ is shown. -1 With 1634cm -1 The nearby absorption peaks are attributed to the stretching vibration of the hydroxyl group and the bending vibration of the water molecule, respectively, at 1390 cm⁻¹. -1 1143 cm -1 and 1106 cm -1 The characteristic peaks at 631 cm⁻¹ correspond to carbonate, C–O bond, and C=O bond, respectively. -1 and 460 cm -1 The absorption peaks at these locations are associated with Co–O and Co–S bonds, respectively. XPS full spectrum analysis of Mo-CCH@Co3S4 / NF confirms that the material contains multiple elements including Ni, Co, Mo, O, C, and S. Figure 3 c). In the fine spectrum of Ni 2p, the characteristic peaks at 873.38 eV and 855.68 eV correspond to Ni 2p, respectively. 1 / 2 With Ni2p 3 / 2 The spin-orbit splitting peak is accompanied by satellite peaks at 879.68 eV and 861.68 eV. Figure 3 d). In the Co 2p spectrum, the characteristic peaks at 780.3 eV and 795.3 eV belong to Co. 3+ The absorption peaks at 782.2 eV and 797.3 eV correspond to Co. 2+ And corresponding satellite peaks appeared at 786.4 eV and 802.6 eV respectively. Figure 3 e). In the Mo 3d spectrum, the characteristic peaks at 232.3 eV and 235.4 eV correspond to the Mo 3d... 5 / 2 and Mo 3d 3 / 2 track( Figure 3 f). The O 1s spectrum can be fitted with three characteristic peaks: 532.5 eV (adsorbed water), 531.2 eV (O–C=O), and 529.8 eV (metal–oxygen bond). Figure 3 g). The C 1s spectrum exhibits three independent characteristic peaks at 288.5 eV, 285.8 eV, and 284.5 eV, corresponding to O–C=O, C–O, and C=C chemical bonds, respectively. Figure 3 h). In the S 2p spectrum, 164.31 eV (S 2p 1 / 2 ) and 161.45 eV (S 2p 3 / 2 The characteristic peaks are typical responses of metal-sulfur bonds, and the absorption peak at 168.38 eV originates from high-valence sulfur on the material surface. Figure 3 i). In summary, the characterization results demonstrate that the Mo-CCH@Co3S4 / NF composite material has been successfully prepared.

[0049] Figure 4 The electrochemical performance of Mo-CCH@Co3S4 / NF was demonstrated. Figure 4 a represents Co-MOF, Co3S4 / NF, Mo-CCH / NF, and Mo-CCH@Co3S4 / NF at a scan rate of 20 mV / s. -1 Cyclic voltammetry (CV) curves were obtained. Among them, the CV curve of Mo-CCH@Co3S4 / NF had the largest closed integral area, indicating that it had the best specific capacity. Figure 4 b shows the electrochemical impedance spectroscopy (EIS) curves of each electrode: the high-frequency region corresponds to the semicircular part of the curve, and the low-frequency region corresponds to the straight line segment. The inset shows the equivalent circuit diagram. The Mo-CCH@Co3S4 / NF electrode has the largest slope of the straight line in the low-frequency region, indicating that the electrolyte diffusion resistance is lower; its charge transfer resistance Rct is only 0.066 Ω, which is lower than that of Co-MOF / NF (0.122 Ω), Co3S4 / NF (0.102 Ω) and Mo-CCH / NF (0.098 Ω), respectively. Figure 4 c represents Mo-CCH@Co3S4 / NF in the range of 1–10 A g. -1 The galvanostatic charge-discharge (GCD) curves at current density show good overall symmetry and a clear charge-discharge plateau, demonstrating the excellent electrochemical reversibility of the electrode. With increasing current density, the specific capacity of all electrodes decreases. Among the four electrodes, Mo-CCH@Co3S4 / NF exhibits the best performance: at 1 A·g -1 The specific capacity can reach 1816.2 C g. -1 Even if the current density is increased to 10 A·g -1 The specific capacity can still be maintained at 1382.1 C g. -1 This demonstrates excellent rate performance. Figure 4 d). As the scan rate increases, the redox peaks of the CV curves of the Mo-CCH@Co3S4 / NF electrode shift towards higher and lower potentials, respectively. This is because the redox reaction time of the active material is insufficient at high scan rates. Meanwhile, the CV curve profiles at different scan rates do not show significant distortion, indicating that the redox reaction of this electrode is highly reversible. Figure 4 e). The redox reaction mechanism corresponding to Mo-CCH@Co3S4 / NF is as follows.

[0050] (1)

[0051] (2)

[0052] (3)

[0053] (4)

[0054] To further investigate the energy storage mechanism of this electrode material, the correlation between the scan rate and peak current in the cyclic voltammetry curves was analyzed. The calculated b values ​​were 0.65 and 0.61, respectively, indicating that the charge storage kinetics of Mo-CCH@Co3S4 / NF are jointly dominated by diffusion-controlled and capacitance-controlled processes, with diffusion-controlled processes being the dominant one. Figure 4 f). At a scan rate of 10 mV s -1 At that time, the capacitance contribution of this material was 18.9% ( Figure 4 g). As the scan rate increases, the contribution of capacitance control gradually increases ( Figure 4 After 10,000 long-cycle tests, the electrode capacity retention rate reached 87.5%, and the coulombic efficiency stabilized at 99.5%. Figure 4 i), demonstrating that Mo-CCH@Co3S4 / NF exhibits excellent cycling stability.

[0055] Figure 5 The structural models, density of states (DOS), adsorption energy, and charge density difference of Co3S4, CCH, Mo-CCH, and Mo-CCH@Co3S4 calculated by density functional theory (DFT) are presented to further elucidate the mechanism by which heterojunctions regulate the electrochemical performance of electrode materials. Figure 5 a–5d represent the microstructure models of the four materials. The d-band centers of the four materials are, in order: Co3S4 (-1.18 eV), CCH (-1.32 eV), Mo-CCH (-1.21 eV), and Mo-CCH@Co3S4 (-1.13 eV). This indicates that Mo-CCH@Co3S4 has the strongest d-electronic state density near the Fermi level, thus exhibiting the best intrinsic conductivity. Figure 5 (e–5h). Compared to CCH, Mo-CCH has more d electronic states at the Fermi level, proving that Mo doping can introduce additional coordination electrons and significantly improve the conductivity of basic cobalt carbonate materials. Figure 5 i represents the charge density difference plot of Mo-CCH@Co3S4, where the yellow and blue regions represent charge accumulation and charge dissipation, respectively, mainly concentrated at the heterojunction interface. Significant charge dissipation is observed on the Mo-CCH side, while a large amount of charge accumulates near the Co3S4 interface. The results indicate that the heterojunction interface can form a space charge region and a built-in electric field, driving efficient electron transfer from Mo-CCH to Co3S4. The electron dissipation region formed on the Mo-CCH surface enhances the adsorption capacity of hydroxide ions, accelerates reaction kinetics, and endows the material with excellent rate performance. Figure 5 j represents Mo-CCH@Co3S4 against OH - The adsorption configuration and adsorption energy calculations show that Mo-CCH@Co3S4 adsorbs OH... - The adsorption energy is -1.9743 eV, significantly lower than that of Co3S4 (-1.2731 eV), CCH (-1.465 eV), and Mo-CCH (-1.7721 eV). Figure 5 k), indicating that the heterojunction pair contains OH in the electrolyte. - It exhibits stronger capture and adsorption capabilities, effectively accelerating the redox reaction rate. This core-shell structure constructs an efficient charge transport pathway: electrons rapidly migrate from the Mo-CCH shell to the Co3S4 core, and are ultimately conducted to the nickel foam current collector; simultaneously, OH- in the electrolyte... - Driven by the built-in electric field, it penetrates the outer shell and diffuses to the core-shell interface, participating in reversible redox reactions to achieve charge compensation. The synergistic effect of the core-shell components ensures high-speed electron transport and provides ample channels for ion diffusion, synergistically improving the electrode's specific capacity, rate performance, and long-cycle stability. Figure 5 The above results indicate that Mo-CCH@Co3S4 / NF is a promising electrode material for supercapacitors.

Claims

1. A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material, characterized in that... A method for preparing a molybdenum-doped basic cobalt carbonate nanosheets@cobalt sulfide nanosheet array / nickel foam composite material as a supercapacitor electrode material is carried out according to the following steps: I. Preparation of Cobalt-Metal-Organic Framework / Nickel Foam (Co-MOF / NF) by Hydrothermal Synthesis 0.58–1.74 g of cobalt nitrate hexahydrate and 1.32–3.96 g of 2-methylimidazole were each dissolved in 40 mL of deionized water. Nickel foam was then placed in the above mixed solution and allowed to stand at room temperature for 4–6 hours. After three washes and drying, cobalt-metal-organic framework / nickel foam (Co-MOF / NF) was finally obtained. II. Preparation of Cobalt Sulfide Nanosheet Arrays / Nickel Foam (Co3S4 / NF) by Hydrothermal Sulfidation Add 90-180 mg of thioacetamide to 30 mL of ethanol, stir for 30 min, transfer to a high-pressure reactor, then add Co-MOF / NF, and react at 120-160 °C for 4-6 h to finally obtain cobalt sulfide nanosheet array / nickel foam (Co3S4 / NF). III. Hydrothermal Preparation of Molybdenum-Doped Basic Cobalt Carbonate Nanosheets@Cobalt Sulfide Nanosheet Array / Nickel Foam (Mo-CCH@Co3S4 / NF) 0.25–1 mmol cobalt nitrate hexahydrate, 0.025–0.1 mmol sodium molybdate dihydrate, and 1.25–5 mmol urea were added to 30 mL of deionized water. The mixture was then transferred to a 50 mL high-pressure reactor, and Co3S4 / NF was added. The mixture was then subjected to a hydrothermal reaction at 120–160 °C for 4–8 h to obtain the composite material Mo-CCH@Co3S4 / NF.

2. The preparation method according to claim 1, characterized in that, In step one, the cobalt nitrate hexahydrate content is 0.58~1.16 g.

3. The preparation method according to claim 1, characterized in that, In step two, the content of thioacetamide is 90~150mg.

4. The preparation method according to claim 1, characterized in that, The hydrothermal time in step three is 6-8 hours.

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