NiMoO4-Co (CO3) 0.5 (OH) composite material

Abstract

The invention discloses a NiMoO4 (at) Co (CO3) 0.5 (OH) composite material, and belongs to the field of supercapacitors. In order to solve the problems of low charge transfer efficiency and low utilization rate of active sites of NiMoO4, the NiMoO4-Co (CO3) 0.5 (OH) composite material with uniform distribution and stable structure is obtained on foamed nickel through a secondary hydrothermal method. The composite material with the micro-sphere and nano needle-shaped heterostructure not only has relatively high specific capacitance, but also has good stability.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor technology, specifically designing a NiMoO4@Co(CO3) capacitor. 0.5 (OH) composite materials and their preparation methods. Background Technology

[0002] Supercapacitors have become a research hotspot due to their advantages such as high power density, fast charge and discharge, ultra-long cycle life, and environmental friendliness, while electrode materials are the core factor determining their performance. Nickel molybdate (NiMoO4) has attracted widespread attention due to its low cost, excellent corrosion resistance, and strong thermodynamic stability, but its relatively weak charge transport efficiency and insufficient utilization of active sites have greatly limited its performance improvement.

[0003] To address these issues, this invention employs a secondary hydrothermal method to construct a heterostructure on nickel molybdate, thereby improving the overall conductivity and charge transport efficiency, while also increasing the number of active sites, thus enhancing the electrochemical performance of the electrode material. Summary of the Invention

[0004] The purpose of this invention is to provide a NiMoO4@Co(CO3) solution. 0.5 (OH) composite materials and their preparation methods. This method combines alkali metal carbonates and nickel molybdate to effectively enhance charge transport efficiency and increases redox reaction sites by utilizing the synergistic effect between heterostructures, thereby improving the electrochemical performance of the electrode material.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A NiMoO4@Co(CO3) 0.5 The preparation method of (OH) composite material involves synthesizing nickel foam containing a NiMoO4 precursor with both nanosheets and microspheres through hydrothermal reaction, and then loading Co(CO3) onto the nickel foam containing the NiMoO4 precursor through secondary hydrothermal reaction. 0.5 Synthesis of NiMoO4@Co(CO3) nanoneedles 0.5 (OH) composite material.

[0006] A NiMoO4@Co(CO3) 0.5 The preparation method of (OH) composite material specifically includes the following steps: (1) Dissolve nickel source and molybdenum source in deionized water in proportion and stir to form a homogeneous solution. Transfer the solution and nickel foam to a reactor for the first hydrothermal reaction. After the reaction is completed, take out the nickel foam, wash and dry it to obtain nickel foam containing NiMoO4 precursor. The NiMoO4 precursor is nanosheet and microsphere composed of nanosheet. (2) Cobalt source, ammonium fluoride and urea are dissolved in deionized water in proportion and stirred to form a homogeneous solution. Then, the nickel foam containing NiMoO4 precursor and the above solution are transferred to a reactor for a second hydrothermal reaction. After the reaction is completed, the nickel foam is taken out, washed and dried to obtain the NiMoO4@Co(CO3). 0.5 (OH) composite material; the NiMoO4@Co(CO3) composite material. 0.5 The morphology of the (OH) composite material includes a heterostructure of microspheres@nanoneedles.

[0007] Furthermore, in step (1), the nickel source is nickel nitrate hexahydrate and the molybdenum source is sodium molybdate dihydrate; the molar ratio of the nickel source to the molybdenum source is 1:1.

[0008] Furthermore, in step (1), the temperature of the first hydrothermal reaction is 150 °C and the hydrothermal time is 6 h.

[0009] Furthermore, in step (2), the cobalt source is cobalt nitrate hexahydrate; the molar ratio of cobalt source, ammonium fluoride and urea is 1:3:8.

[0010] Furthermore, in step (2), the temperature of the second hydrothermal reaction is 120 °C and the hydrothermal time is 12 h.

[0011] The NiMoO4@Co(CO3) prepared by the above method 0.5 (OH) composite material.

[0012] Application: The NiMoO4@Co(CO3) mentioned above 0.5 Application of (OH) composite materials as electrode materials in supercapacitors.

[0013] The beneficial effects of this invention are as follows: This invention synthesizes NiMoO4@Co(CO3). 0.5 (OH) composite material, utilizing Co(CO3) 0.5 (OH) Excellent electronic conductivity improves the conductivity of NiMoO4 and increases the utilization rate of its active sites. The microsphere heterostructure wrapped in nanoneedles increases the redox reaction sites and conductivity of the material, thereby improving the specific capacitance and stability of the composite electrode material as a whole. Attached Figure Description

[0014] Figure 1-1 The images shown are scanning electron microscope (SEM) images of the electrode materials in Examples 1-2 of this invention; (a1, a2) represent Example 1, and (b1, b2) represent Example 2. Figure 1-2 The images shown are scanning electron microscope (SEM) images of the electrode materials in Examples 3-5 of the present invention; (c1, c2) represent Example 3, (d1, d2) represent Example 4, and (e1, e2) represent Example 5. Figure 1-3 The images shown are scanning electron microscope (SEM) images of the electrode materials in Examples 6-7 of the present invention; (f1, f2) are from Example 6, and (g1, g2) are from Example 7. Figure 2 The images show the XRD patterns of the electrode materials in Embodiments 1, 2, and 4 of this invention. Figure 3 In the diagram, a is a schematic diagram of the cyclic voltammetry curves of the electrode materials in Examples 1-7 of the present invention, and b is a constant current charge-discharge diagram; Figure 4-1 In the figures, a and b are constant current charge-discharge curves of the electrode materials in Examples 1-2 of the present invention under different current densities; Figure 4-2 cg represents the constant current charge-discharge curves of the electrode materials in Examples 3-7 of this invention under different current densities, and h represents the specific capacitance of the electrode materials in Examples 1-7 under different current densities. Figure 5 The Nyquist plots and equivalent circuit diagrams for embodiments 1, 2, and 4 of this invention are shown below. Figure 6 The graphs show the cyclic stability of the electrode materials in Embodiments 1, 2, and 4 of this invention. Detailed Implementation

[0015] To make the content of this invention easier to understand, the technical solutions of this invention will be further described below in conjunction with specific embodiments, but this does not limit the scope of this invention.

[0016] Example 1: NiMoO4 electrode material (1) The nickel foam was soaked in acetone and 3 M hydrochloric acid solution for 20 min in turn, then washed with deionized water and anhydrous ethanol three times in turn, and finally dried at 60 °C for 6 h.

[0017] (2) Dissolve 0.233 g Ni(NO3)2·6H2O and 0.194 g Na2MoO4·2H2O in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the treated nickel foam and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 150 °C for 6 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain NiMoO4 electrode material.

[0018] Example 2: Co(CO3) 0.5 (OH) electrode material (1) The nickel foam was soaked in acetone and 3 M hydrochloric acid solution for 20 min in turn, then washed with deionized water and anhydrous ethanol three times in turn, and finally dried at 60 °C for 6 h.

[0019] (2) Dissolve 0.291 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the treated nickel foam and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 12 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain Co(CO3). 0.5 (OH) electrode material.

[0020] Example 3: NiMoO4@Co(CO3) 0.5 (OH)-1 electrode material (1) The steps for synthesizing nickel foam containing NiMoO4 precursor are the same as in Example 1.

[0021] (2) Dissolve 0.146 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the nickel foam containing the NiMoO4 precursor and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 12 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain NiMoO4@Co(CO3). 0.5 (OH)-1 electrode material.

[0022] Example 4: NiMoO4@Co(CO3) 0.5 (OH)-2 electrode material (1) The steps for synthesizing nickel foam containing NiMoO4 precursor are the same as in Example 1.

[0023] (2) Dissolve 0.291 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the nickel foam containing the NiMoO4 precursor and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 12 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain NiMoO4@Co(CO3). 0.5 (OH)-2 electrode material.

[0024] Example 5: NiMoO4@Co(CO3) 0.5 (OH)-3 electrode material (1) The steps for synthesizing nickel foam containing NiMoO4 precursor are the same as in Example 1.

[0025] (2) 0.437 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea were dissolved in 40 mL of deionized water and stirred to obtain a homogeneous solution. The nickel foam containing the NiMoO4 precursor and the above solution were transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and reacted at 120 °C for 12 h. The nickel foam was removed, washed several times with deionized water and ethanol, and then dried at 60 °C for 12 h to obtain NiMoO4@Co(CO3). 0.5 (OH)-3 electrode material.

[0026] Example 6: NiMoO4@Co(CO3) 0.5 (OH)-4 electrode material (1) The steps for synthesizing nickel foam containing NiMoO4 precursor are the same as in Example 1.

[0027] (2) Dissolve 0.582 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the nickel foam containing the NiMoO4 precursor and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 12 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain NiMoO4@Co(CO3). 0.5 (OH)-4 electrode material.

[0028] Example 7: NiMoO4@Co(CO3) 0.5 (OH)-5 electrode material (3) The steps for synthesizing nickel foam containing NiMoO4 precursor are the same as in Example 1.

[0029] (4) Dissolve 0.728 g Co(NO3)2·6H2O, 0.111 g NH4F, and 0.480 g urea in 40 mL of deionized water and stir to obtain a homogeneous solution. Transfer the nickel foam containing the NiMoO4 precursor and the above solution to a 50 mL stainless steel reactor lined with polytetrafluoroethylene and react at 120 °C for 12 h. Remove the nickel foam, wash it several times with deionized water and ethanol, and dry it at 60 °C for 12 h to obtain NiMoO4@Co(CO3). 0.5 (OH)-5 electrode material.

[0030] Product characterization and performance testing 1. Morphological characteristics Figure 1-1 , Figure 1-2 and Figure 1-3 These are scanning electron microscope (SEM) images of the electrode materials used in Examples 1-7. Figure 1-1 As shown in (a1, a2), NiMoO4 exists as two-dimensional nanosheets, with some nanosheets assembling into microspheres. The nanosheets are uniformly grown on nickel foam and are densely distributed. Figure 1-1 In (b1), Co(CO3) 0.5 (OH) consists of flakes. From high-magnification SEM (… Figure 1-1 As can be seen in (b2), the sheet-like Co(CO3) 0.5 (OH) is woven from many nanoneedles. For example... Figure 1-2 and Figure 1-3 (c1-g1), Co(CO3) 0.5 (OH) nanoneedles are grown on a NiMoO4 nanosheet substrate and a microsphere framework to form NiMoO4@Co(CO3). 0.5 (OH) core-shell heterostructure. This core-shell heterostructure effectively combines the structures of the two components, which may be beneficial for providing additional electrochemical reactive sites for the electrode material and improving its electrochemical performance. From high-magnification SEM (… Figure 1-2 and Figure 1-3 As can be seen from (c2-g2)), with the increase of Co content, NiMoO4@Co(CO3) 0.5 The structure of (OH) changes from a flower-like shape with needles and scales to a radiating, distinct sea urchin-like structure.

[0031] 2. Phase Characterization Figure 2 For NiMoO4 and Co(CO3) 0.5 (OH) and NiMoO4@Co(CO3) 0.5 XRD pattern of (OH)⁻⁂. Characteristic peaks at 2θ of 13.58°, 27.50°, and 29.79° correspond to NiMoO₄ (PDF#97-024-7435). For Co(CO₃)⁻… 0.5 (OH), the diffraction peaks at 17.51°, 33.82° and 39.52° match the (020), (221) and (231) crystal planes of card 048-0083. Composite electrode material NiMoO4@Co(CO3) 0.5 The presence of diffraction peaks for both (OH) and the absence of other obvious impurity peaks indicates that the composite electrode material was successfully prepared.

[0032] 3. Supercapacitor Performance Testing The performance of the supercapacitor was tested using a three-electrode system. The prepared electrode was the working electrode, the platinum electrode was the auxiliary electrode, the reference electrode was the Hg / HgO electrode, and the electrolyte was a 3 M KOH solution.

[0033] Figure 3 In Figure (a), the cyclic voltammetry curves of the electrode materials in Examples 1-7 at a scan rate of 50 mV / s all show obvious redox peaks, consistent with typical battery-type Faraday reactions. After normalization, NiMoO4@Co(CO3) 0.5 (OH)-2 has the largest CV integral area, indicating that the flower-shaped heterostructure with coexisting needles and lamellae provides more active sites and promotes redox reactions. Figure 3 Figure (b) shows the constant current charge-discharge curves at a current density of 1 A / g for NiMoO4 and Co(CO3). 0.5 (OH) and five NiMoO4@Co(CO3) 0.5 The specific capacitances of the (OH) composite electrodes were 269.41 F / g, 902.93 F / g, 1318.63 F / g, 1693.98 F / g, 1581.58 F / g, 1201.08 F / g, and 946.05 F / g, respectively, indicating that NiMoO4@Co(CO3) 0.5 (OH)-2 has the largest specific capacitance.

[0034] Figure 4-1 and Figure 4-2 Figure 1(ag) shows the constant current charge-discharge curves of the electrode materials in Examples 1-7 at different current densities. The charge-discharge curves of the electrodes exhibit almost symmetrical charge-discharge times at both low and high current densities, indicating that they have excellent reversibility during the charge-discharge process. Figure 4-2 In the figure (h), the specific capacitance of the electrode materials in Examples 1-7 under different current densities is shown. The values ​​for NiMoO4@Co(CO3) at current densities of 1, 2, 5, 8, and 10 A / g are also shown. 0.5 (OH)-2 exhibits the largest specific capacitance, retaining 57.3% of its initial capacitance even at 10 A / g.

[0035] Figure 5 For NiMoO4 and Co(CO3) 0.5 (OH) and NiMoO4@Co(CO3) 0.5 The EIS diagram of (OH)⁻⁂ was obtained. The values ​​of NiMoO₄ and Co(CO₃) were obtained through circuit fitting. 0.5 (OH) and NiMoO4@Co(CO3) 0.5 (OH)-2's R ct The resistances are 2.54 Ω, 0.159 Ω, and 2.1 Ω, respectively. (Co(CO3)) 0.5 (OH) has the lowest charge transfer resistance compared to NiMoO4, and NiMoO4@Co(CO3) has the lowest resistance. 0.5The resistance of (OH)-2 decreased significantly, indicating that the heterostructure can improve the diffusion pathway and charge transfer of ions, thereby promoting charge transport.

[0036] Figure 6 For NiMoO4 and Co(CO3) 0.5 (OH) and NiMoO4@Co(CO3) 0.5 Cyclic stability curves of (OH)-2. After 5000 CV cycles, NiMoO4 and Co(CO3) 0.5 (OH) and NiMoO4@Co(CO3) 0.5 The retention rates of (OH)-2 were 105.15%, 92.10%, and 114.42%, respectively.

[0037] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a NiMo04@Co(C03) 0.5 (OH) composite material, characterized by: A NiMoO4 precursor coexisting with nanosheets and microspheres was synthesized on foamed nickel by a hydrothermal reaction, and Co(CO3) 0.5 (OH) nanoneedles were synthesized on the NiMoO4@Co(CO3) 0.5 (OH) composite.

2. The production method according to claim 1, characterized by, Specifically comprising the following steps: (1) Dissolve a nickel source and a molybdenum source in deionized water in a proportion, stir to form a uniform solution, and transfer the solution and foamed nickel to a reaction kettle to perform a first hydrothermal reaction; after the reaction is completed, remove the foamed nickel, clean and dry it, and obtain foamed nickel containing a NiMoO4 precursor; (2) The cobalt source, ammonium fluoride and urea are dissolved in deionized water in proportion, stirred to form a uniform solution, and then the foam nickel containing the NiMoO4 precursor and the above solution are transferred to a reaction kettle for secondary hydrothermal reaction. After the reaction is completed, the foam nickel is taken out, washed and dried to obtain the NiMoO4@Co(CO3) 0.5 (OH) composite material.

3. The method of claim 2, wherein: In step (1), the nickel source is nickel nitrate hexahydrate, and the molybdenum source is sodium molybdate dihydrate; the molar ratio of the nickel source to the molybdenum source is 1:

1.

4. The method of claim 2, wherein: In step (1), the first hydrothermal reaction temperature is 150 ℃, and the hydrothermal time is 6 h.

5. The method of claim 2, wherein: In step (2), the cobalt source is cobalt nitrate hexahydrate; the molar ratio of the cobalt source to ammonium fluoride and urea is 1:3:

8.

6. The method of claim 2, wherein: In step (2), the second hydrothermal reaction temperature is 120 ℃, and the hydrothermal time is 12 h.

7. The NiMo04@Co(C03) (OH) composite material prepared according to the preparation method of any one of claims 1-6. 0.5 (OH) composite material.

8. The NiMoO4@Co(CO3) 0.5 application of the NiMoO4@Co(CO3) (OH) composite as electrode material in supercapacitors.

Images