Preparation Method and Application of a Carbon Nanotube Film-Supported Cu-MOF / NiCoP Composite Electrode

Abstract

The present invention belongs to the technical field of composite materials, and relates to a preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode, which includes: first, obtaining a CNTs film by vacuum filtration of a CNTs dispersion; then quickly mixing the obtained CNTs film with a copper hydroxide colloid dispersion, adding an H3BTC solution after standing to obtain a CNTs@Cu-MOF film; in a three-electrode system, using the CNTs@Cu-MOF as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode, preparing an electrolyte with nickel nitrate, cobalt nitrate, and sodium hypophosphite as solutes, electro-depositing in a voltage window of -1.2 - 0.2 V, washing, and drying at 60 °C to obtain a CNTs@Cu-MOF / NiCoP film, which can be applied to the electrode of a supercapacitor. The present invention enhances the flexibility and conductivity of the material with a carbon nanotube film as the substrate, and at the same time avoids the use of binders and conductive agents. Meanwhile, by utilizing the high specific surface area of Cu-MOF and the high-capacity NiCoP, it can effectively reduce the impedance of the material, increase the accessible specific surface area of electrolyte ions, and provide a large number of active sites for reactions.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, relates to electrode materials, and particularly relates to a preparation method and application of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode. Background Art

[0002] The rapid rise of the new energy industry and the rapid development of various electronic devices have expanded the market demand in the energy storage field. Among many energy storage devices, supercapacitors have continuously grown in the overall market scale due to advantages such as short charging time, high cycle stability, and environmental friendliness. However, the reality is that the shortcoming of low energy density limits the application of supercapacitors in some fields. Supercapacitors mainly rely on redox reactions occurring on the electrode surface and ion adsorption for energy storage. Therefore, preparing high-performance electrodes is crucial for improving the energy density of supercapacitors.

[0003] Metal-organic framework (MOFs) materials have unique structural advantages such as large specific surface area, abundant active sites, and excellent porosity, and are recognized as highly potential energy storage device materials. However, most MOFs have poor conductivity and stability and cannot achieve the expected excellent performance. Carbon nanotubes, which are currently widely used as conductive substrates, provide a feasible solution for the design of flexible electrode materials due to their excellent electrical conductivity, outstanding stability, and mechanical flexibility. In addition, their hollow structure can provide a suitable specific surface area for ions to enter, and the open network tubular structure becomes a good carrier for active substances, with abundant electrochemical active sites and shortened electron and ion transport paths. However, due to the relatively small specific surface area of carbon nanotubes, it is difficult to improve the pseudocapacitance effect and specific capacity through modification.

[0004] Transition metal phosphides are potential candidates for innovative electrode materials, mainly because of their metal-like properties, excellent electrical conductivity, high theoretical capacity, and improved reaction kinetics. The low electronegativity of phosphorus can promote electron transport and exhibit better redox activity. In addition, transition metal phosphides have advantages such as abundant reserves, good thermal stability, and environmental friendliness, ensuring their large-scale commercial utilization in energy storage and conversion. Among them, due to the coexistence and synergistic effect of two metal elements, bimetallic phosphides often have higher electrical conductivity and better electrochemical activity than single-component phosphides. The combination of MOF and bimetallic phosphide can improve the conductivity of MOF and show better electrochemical performance. Summary of the Invention

[0005] Aiming at the deficiencies existing in the above-mentioned prior art, the purpose of the present invention is to disclose a preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode.

[0006] Technical Solution

[0007] Using copper nitrate trihydrate (Cu(NO3)2·2.5H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), benzenetricarboxylic acid (H3BTC), and carbon nanotubes (CNTs) as raw materials, first obtain a carbon nanotube film by suction filtration, and then use a simple and rapid chemical reaction method to obtain CNTs@Cu-MOF. After electrodeposition, a CNTs@Cu-MOF / NiCoP composite film material is obtained.

[0008] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0009] A. Obtain a CNTs film by vacuum suction filtration of the CNTs dispersion;

[0010] B. Rapidly mix the obtained CNTs film with a copper hydroxide colloid dispersion, and after standing for 1-2 h, add an H3BTC solution, and stand for 24 h or more to obtain a CNTs@Cu-MOF film;

[0011] C. In a three-electrode system, use the CNTs@Cu-MOF film as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode. Using nickel nitrate (Ni(NO3)2), cobalt nitrate (Co(NO3)2), and sodium hypophosphite (NaH2PO2) as solutes and a mixed solution of deionized water and ethanol as the solvent, prepare an electrolyte solution, and perform electrodeposition by cyclic voltammetry. After completion, take out the film and wash it several times with deionized water and absolute ethanol, and dry it at 60 °C to obtain a CNTs@Cu-MOF / NiCoP composite electrode.

[0012] In a preferred disclosure example of the present invention, the concentration of the CNTs dispersion in step A is 1.5 mg mL -1 , and the volume is 1-2 mL.

[0013] In a preferred disclosure example of the present invention, the volume of the copper hydroxide colloid dispersion in step B is 100-200 mL, and the concentration of the H3BTC solution is 10-15 mM.

[0014] In a preferred disclosure example of the present invention, the molar ratio of Ni(NO3)2, Co(NO3)2, and NaH2PO2 in step C is 1:1:2, and the volume ratio of the two in the mixed solution of deionized water and ethanol is 1:1-1:1.5, and an electrolyte solution with a concentration of 0.05-0.1 M is prepared.

[0015] In a preferred disclosure example of the present invention, the cyclic voltammetry in step C is carried out for electrodeposition in a voltage window of -1.2 to 0.2 V, and the scanning rate is 5-10 mV s -1 .

[0016] According to the method disclosed in the present invention, the size of the prepared carbon nanotube film-supported Cu-MOF / NiCoP composite film can be cut arbitrarily according to the actual situation, and its microscopic morphology is a Cu-MOF / NiCoP polyhedral structure loaded on the surface of carbon nanotubes.

[0017] Another object of the present invention is to use the prepared carbon nanotube film-supported Cu-MOF / NiCoP composite film as a positive electrode material for supercapacitors.

[0018] Using the prepared CNTs@Cu-MOF / NiCoP composite film material as the positive electrode material, with a 6 mol / L aqueous KOH solution as the electrolyte, mixing activated carbon, conductive carbon black, and binder evenly at a mass ratio of 8:1:1 and dispersing them in a solvent, then coating them on nickel foam, drying, and pressing to prepare an electrode sheet as the negative electrode material of the capacitor. Electrochemical performance tests such as cyclic voltammetry (CV) and constant current charge and discharge are carried out in a two-electrode system, and the corresponding energy density and power density are calculated to evaluate the electrochemical performance of the prepared CNTs@Cu-MOF / NiCoP composite film material. Among them, the voltage range of the cyclic voltammetry (CV) test is 0 to 0.5 V, the scanning speeds are 2, 5, 10, 20, 50, and 100 mV / s, the voltage range of the constant current charge and discharge test is 0 to 0.5 V, and the current densities are 1, 2, 3, 5, 8, and 10 A / g.

[0019] The prepared CNTs@Cu-MOF / NiCoP composite film electrode material of the present invention uses instruments such as a scanning electron microscope (SEM) and a CHI760E electrochemical workstation to analyze the structure and performance of the product to evaluate its electrochemical activity.

[0020] The unique hollow structure of carbon nanotubes can provide a suitable specific surface area to facilitate the entry of ions, and the open network tubular structure becomes a good carrier for active substances.

[0021] All the reaction reagents used in the present invention are commercially available, copper nitrate trihydrate (Cu(NO3)2·2.5H2O), cobalt nitrate hexahydrate (Co(NO3)2·6H2O), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), sodium hypophosphite (NaH2PO2·H2O), trimesic acid (H3BTC), carbon nanotubes (CNTs).

[0022] Beneficial effects

[0023] The CNTs@Cu-MOF / NiCoP composite film electrode material synthesized by the present invention uses carbon nanotubes as the substrate, which greatly enhances the flexibility and conductivity of the material. At the same time, Cu-MOF / NiCoP grows in-situ on the carbon nanotube film, and the resulting electrode avoids the use of adhesives, effectively reducing the internal resistance of the electrode. MOF can also maximize the ion-accessible specific surface area and provide a large number of active sites for reactions. Description of the Drawings

[0024] Figure 1 . Scanning electron microscope image of the surface of the CNTs@Cu-MOF / NiCoP composite film electrode material prepared in Example 2;

[0025] Figure 2 . Cross-sectional scanning electron microscope image of the CNTs@Cu-MOF / NiCoP composite film electrode material prepared in Example 2;

[0026] Figure 3 . GCD curve of the CNTs@Cu-MOF / NiCoP composite film electrode material prepared in Example 2;

[0027] Figure 4 . Energy density-power density diagram of the supercapacitor assembled with the CNTs@Cu-MOF / NiCoP composite film electrode material prepared in Example 2;

[0028] Figure 5 . Cyclic stability diagram of the supercapacitor assembled with the CNTs@Cu-MOF / NiCoP composite film electrode material prepared in Example 2. Detailed Description of the Invention

[0029] The present invention will be described in detail below in conjunction with the embodiments, so that those skilled in the art can better understand the present invention. However, the present invention is not limited to the following embodiments.

[0030] Unless otherwise defined, the terms (including scientific and technical terms) used herein shall be interpreted as having the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. It will also be understood that the terms used herein shall be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and shall not be interpreted in an idealized or excessive form unless specifically so defined herein.

[0031] Example 1

[0032] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0033] 1. First, the concentration is 1.5 mg mL -1The CNTs dispersion was filtered through vacuum filtration to obtain a CNTs film, and the volume of the CNTs dispersion was 1 mL;

[0034] 2. The obtained CNTs film was rapidly mixed with a copper hydroxide colloid dispersion. The volume of the dispersion was 100 mL. After standing for 1 h, a solution of benzenetricarboxylic acid (H3BTC) with a concentration of 10 mM was added, and after standing for 24 h, a CNTs@Cu-MOF film was obtained;

[0035] 3. In a three-electrode system, the CNTs@Cu-MOF film was used as the working electrode, Ag / AgCl as the reference electrode, Pt as the counter electrode, and a mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) as the electrolyte. The solvent was a mixed solution of deionized water and ethanol, and the volume ratio of the two was 1:1 to 1:1.5. Cyclic voltammetry was used with a scanning rate of 5 mV s -1 , and electrodeposition was carried out in a voltage window of -1.2 - 0.2 V. Finally, the film was taken out and washed several times with deionized water and absolute ethanol, and dried at 60 °C to obtain a CNTs@Cu-MOF / NiCoP film.

[0036] When the prepared CNTs@Cu-MOF / NiCoP composite film is applied as a supercapacitor electrode material, its power density is 1600 W / kg when the energy density reaches 49.2 Wh / kg.

[0037] Example 2

[0038] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0039] 1. First, a CNTs dispersion with a concentration of 1.5 mg mL -1 The CNTs dispersion was filtered through vacuum filtration to obtain a CNTs film, and the volume of the CNTs dispersion was 1.5 mL;

[0040] 2. The obtained CNTs film was rapidly mixed with a copper hydroxide colloid dispersion. The volume of the dispersion was 100 mL. After standing for 2 h, a solution of benzenetricarboxylic acid (H3BTC) with a concentration of 15 mM was added, and after standing for 24 h, a CNTs@Cu-MOF film was obtained;

[0041] 3. In a three-electrode system, the CNTs@Cu-MOF film was used as the working electrode, Ag / AgCl as the reference electrode, Pt as the counter electrode, and a mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) as the electrolyte. The solvent was a mixed solution of deionized water and ethanol, and the volume ratio of the two was 1:1. Cyclic voltammetry was used with a scanning rate of 10 mV s -1, electro-deposition was carried out in a voltage window of -1.2 - 0.2 V. Finally, the film was taken out and washed several times with deionized water and absolute ethanol, and dried at 60 °C to obtain the CNTs@Cu-MOF / NiCoP film.

[0042] When the prepared CNTs@Cu-MOF / NiCoP composite film is used as a supercapacitor electrode material, its power density is 2400 W / kg when the energy density reaches 41.1 Wh / kg.

[0043] Characterization and analysis of the carbon nanotube film-supported Cu-MOF / NiCoP composite film electrode material are as follows.

[0044] As Figure 1 shown, it can be seen from the figure that the CNTs@Cu-MOF / NiCoP composite material is connected together by polyhedrons in the microscopic state, forming an integrated grid structure.

[0045] As Figure 2 shown, it can be seen from the figure that the cross-section of the CNTs@Cu-MOF / NiCoP composite material shows an obvious layered structure in the microscopic state, forming a composite film with a thickness of 10 μm.

[0046] As Figure 3 shown, it can be seen from the figure that the GCD curve of the CNTs@Cu-MOF / NiCoP composite material has good symmetry.

[0047] As Figure 4 shown, for the application of the CNTs@Cu-MOF / NiCoP composite material prepared in this example as a supercapacitor electrode material in a two-electrode system, it can be seen from the energy density-power density figure that the assembled supercapacitor has good power density and energy density. When the maximum energy density reaches 57.8 Wh / kg, its power density is 800 W / kg.

[0048] As Figure 5 shown, for the results of the cyclic stability test of the CNTs@Cu-MOF / NiCoP / / activated carbon composite material prepared in this example used as an electrode material, its specific capacitance remained 80.6% of the initial capacitance after 10,000 cycles.

[0049] Example 3

[0050] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0051] 1. First, a CNTs dispersion with a concentration of 1.5 mg mL -1 was used to obtain a CNTs film by vacuum filtration. The volume of the CNTs dispersion was 1.5 mL;

[0052] 2. Rapidly mix the obtained CNTs film with the copper hydroxide colloidal dispersion. The volume of the dispersion is 100 mL. After standing for 1.5 h, add a solution of benzenetricarboxylic acid (H3BTC) with a concentration of 13 mM, and stand for 24 h to obtain the CNTs@Cu-MOF film;

[0053] 3. In a three-electrode system, use the CNTs@Cu-MOF film as the working electrode, Ag / AgCl as the reference electrode, Pt as the counter electrode, and a mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) as the electrolyte. The solvent is a mixed solution of deionized water and ethanol with a volume ratio of 1:1.5. Adopt cyclic voltammetry with a scanning rate of 8 mV s -1 , and perform electrodeposition in a voltage window of -1.2 - 0.2 V. Finally, take out the film, wash it several times with deionized water and absolute ethanol, and dry it at 60 °C to obtain the CNTs@Cu-MOF / NiCoP film.

[0054] When the prepared CNTs@Cu-MOF / NiCoP composite film is applied as a supercapacitor electrode material, its power density is 4000 W / kg when the energy density reaches 34.2 Wh / kg.

[0055] Example 4

[0056] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0057] 1. First, obtain the CNTs film by vacuum filtration of the CNTs dispersion with a concentration of 1.5 mg mL -1 The volume of the CNTs dispersion is 1.2 mL;

[0058] 2. Rapidly mix the obtained CNTs film with the copper hydroxide colloidal dispersion. The volume of the dispersion is 100 mL. After standing for 1.7 h, add a solution of benzenetricarboxylic acid (H3BTC) with a concentration of 14 mM, and stand for 24 h to obtain the CNTs@Cu-MOF film;

[0059] 3. In a three-electrode system, use the CNTs@Cu-MOF film as the working electrode, Ag / AgCl as the reference electrode, Pt as the counter electrode, and a mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) as the electrolyte. The solvent is a mixed solution of deionized water and ethanol with a volume ratio of 1:1.2. Adopt cyclic voltammetry with a scanning rate of 6 mV s -1, electro-deposition was carried out in a voltage window of -1.2 - 0.2 V. Finally, the film was taken out and washed several times with deionized water and absolute ethanol, and dried at 60 °C to obtain the CNTs@Cu-MOF / NiCoP film.

[0060] When the prepared CNTs@Cu-MOF / NiCoP composite film is used as a supercapacitor electrode material, its power density is 8000 W / kg when the energy density reaches 25.5 Wh / kg.

[0061] Example 5

[0062] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0063] 1. First, a CNTs dispersion with a concentration of 1.5 mg mL -1 was used to obtain a CNTs film by vacuum filtration. The volume of the CNTs dispersion was 1.1 mL;

[0064] 2. The obtained CNTs film was quickly mixed with a copper hydroxide colloid dispersion. The volume of the dispersion was 100 mL. After standing for 1.9 h, a solution of 11 mM benzenetricarboxylic acid (H3BTC) was added, and the CNTs@Cu-MOF film was obtained after standing for 24 h;

[0065] 3. In a three-electrode system, the CNTs@Cu-MOF film was used as the working electrode, Ag / AgCl as the reference electrode, Pt as the counter electrode, and a mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) as the electrolyte. The solvent was a mixed solution of deionized water and ethanol with a volume ratio of 1:1.1. Cyclic voltammetry was used with a scanning rate of 9 mV s -1 , electro-deposition was carried out in a voltage window of -1.2 - 0.2 V. Finally, the film was taken out and washed several times with deionized water and absolute ethanol, and dried at 60 °C to obtain the CNTs@Cu-MOF / NiCoP film.

[0066] When the prepared CNTs@Cu-MOF / NiCoP composite film is used as a supercapacitor electrode material, its power density is 6400 W / kg when the energy density reaches 28.9 Wh / kg.

[0067] Example 6

[0068] A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode includes the following steps:

[0069] 1. First, a CNTs dispersion with a concentration of 1.5 mg mL -1The CNTs dispersion was used to obtain a CNTs film by vacuum filtration. The volume of the CNTs dispersion was 1.4 mL.

[0070] 2. The obtained CNTs film was rapidly mixed with a copper hydroxide colloid dispersion. The volume of the dispersion was 100 mL. After standing for 2 h, a solution of benzenetricarboxylic acid (H3BTC) with a concentration of 15 mM was added. After standing for 24 h, a CNTs@Cu-MOF film was obtained.

[0071] 3. In a three-electrode system, the CNTs@Cu-MOF film was used as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode. A mixed solution of Ni(NO3)2, Co(NO3)2, and sodium hypophosphite (NaH2PO2·H2O) was used as the electrolyte. The solvent was a mixed solution of deionized water and ethanol with a volume ratio of 1:1.0. Cyclic voltammetry was used with a scan rate of 10 mV s -1 , and electrodeposition was carried out in a voltage window of -1.2 - 0.2 V. Finally, the film was taken out and washed several times with deionized water and absolute ethanol, and dried at 60 °C to obtain a CNTs@Cu-MOF / NiCoP film.

[0072] When the prepared CNTs@Cu-MOF / NiCoP composite film was used as a supercapacitor electrode material, the power density was 800 W / kg when the energy density reached 58.8 Wh / kg.

[0073] The above are only the embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the description of the present invention, or direct or indirect application in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A preparation method of a carbon nanotube film-supported Cu-MOF / NiCoP composite electrode, characterized in that, It includes the following steps: A. Obtain a CNTs film by vacuum filtration of the CNTs dispersion. B. Rapidly mix the obtained CNTs film with a copper hydroxide colloid dispersion, let it stand for 1 - 2 h, then add the H3BTC solution, and let it stand for 24 h or more to obtain the CNTs@Cu-MOF film. C. In a three-electrode system, use the CNTs@Cu-MOF film as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode. Prepare an electrolyte with nickel nitrate, cobalt nitrate, and sodium hypophosphite as solutes and a mixed solution of deionized water and ethanol as the solvent. Perform electro-deposition using cyclic voltammetry. After completion, take out the film, wash it several times with deionized water and absolute ethanol, and dry it at 60 °C to obtain the CNTs@Cu-MOF / NiCoP composite electrode.

2. The preparation method of the carbon nanotube film-supported Cu-MOF / NiCoP composite electrode according to claim 1, wherein: The concentration of the CNTs dispersion liquid described in step A is 1.5 mg mL -1 , and the volume is 1-2 mL.

3. The preparation method of the carbon nanotube film-supported Cu-MOF / NiCoP composite electrode according to claim 1, wherein: In step B, the volume of the copper hydroxide colloid dispersion is 100 - 200 mL, and the concentration of the H3BTC solution is 10 - 15 mM.

4. The preparation method of the carbon nanotube film-supported Cu-MOF / NiCoP composite electrode according to claim 1, characterized in that: In step C, the molar ratio of nickel nitrate, cobalt nitrate, and sodium hypophosphite is 1:1:2, and the volume ratio of the two in the mixed solution of deionized water and ethanol is 1:1 - 1:1.5, and an electrolyte with a concentration of 0.05 - 0.1 M is prepared.

5. The preparation method of the carbon nanotube film-supported Cu-MOF / NiCoP composite electrode according to claim 1, characterized in that: The cyclic voltammetry described in step C is used for electrodeposition within a voltage window of -1.2 to 0.2 V, and the scanning rate is 5 to 10 mV s -1 .

6. A carbon nanotube film-supported Cu-MOF / NiCoP composite electrode prepared by the method according to any one of claims 1 - 5.

7. The carbon nanotube film-supported Cu-MOF / NiCoP composite electrode according to claim 6, wherein: Its microscopic morphology is a Cu-MOF / NiCoP polyhedral structure loaded on the surface of carbon nanotubes.

8. Application of the carbon nanotube film-supported Cu-MOF / NiCoP composite electrode as described in claim 6 or 7, characterized in that: Apply it as the positive electrode material of a supercapacitor.

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