CN115975213B - Nickel-based metal organic framework prepared based on solvothermal synthesis method, synthesis method and application thereof - Google Patents

Abstract

The invention discloses a nickel-based metal organic framework prepared based on a solvothermal synthesis method, a synthesis method and application thereof, and belongs to the technical field of resources and environment. The synthesis method comprises the following steps: dissolving metal salt in an organic solvent to obtain a solution A; (2) Dissolving an organic ligand in an organic solvent to obtain a solution B; (3) Adding the solution A and the solution B into a reaction kettle for solvothermal reaction; (4) Filtering, washing and drying a solid product obtained by the reaction to obtain a nickel-based metal organic framework; the metal salt comprises a nickel salt. The preparation method of the invention is simple, low in cost and easy for mass production. The prepared nickel metal organic framework has larger specific surface area, multiple morphologies such as nano rods, lamellar nano belts, nanospheres, nano sheets and the like, and good stability and electrochemical performance.

Description

A nickel-based metal-organic framework prepared based on solvothermal synthesis method and synthesis method and its applications

Technical field

The invention relates to the field of resources and environmental technology, and in particular to a nickel-based metal-organic framework prepared based on solvothermal synthesis, a synthesis method and its application.

Background technique

Metal-organic frameworks (MOFs) are a type of porous nanomaterials with a periodic network structure formed by self-assembled connections between metal ions or metal clusters and organic ligands. The material has the characteristics of large specific surface area, flexible pore structure, many active sites, high thermal stability, recyclability, and adjustable structure. The uniformly dispersed coordinated unsaturated metal sites in the material make MOFs materials have broad application prospects in the field of energy storage.

Studies have shown that MOFs materials can be used in electrode materials for batteries, capacitors, and supercapacitors. Among them, commonly used electrode materials for supercapacitors are carbon-based materials, conductive polymers, and metal oxides. The electrochemical performance of supercapacitors is closely related to the porosity, specific surface area, size and crystallinity of electrode materials. The modifiable porous structure and high specific surface area of MOFs materials enable them to have sufficient electrically active sites for supercapacitor charge storage, and are considered to have excellent electrode material potential. Although the ordered porous structure of MOFs materials is beneficial to the performance of supercapacitors, some inherent characteristics of the materials are not conducive to electrochemical reactions, thus limiting their application in supercapacitors. For example, although MOFs have a porous structure, the pore sizes of many MOFs are smaller than the ions in the electrolyte and are not suitable for ion transport. Moreover, in MOFs materials, because the metal central ions and coordination ions rely on covalent bonds and van der Waals forces to connect, The structure is not very stable, and the charging and discharging process of the pseudocapacitor is a process of continuous intercalation and deintercalation of ions, so its cycle life will be limited. In addition, there is a problem of insufficient water stability when MOFs materials are used to treat water pollutants. Due to the weak coordination between metal-organic ligands, the MOFs skeleton is easily attacked by water molecules, causing problems such as ligand displacement and structural decomposition, resulting in loss of porosity.

Contents of the invention

In view of the above-mentioned problems of water stability and insufficient conductivity of MOFs, the present invention provides a nickel-based metal-organic framework prepared by a solvothermal synthesis method, a synthesis method and its application. By doping and modifying the parent MOFs material with metal, the structural stability of the material and the electrochemical performance of the material are improved without changing the original network topology.

In order to achieve the above objects, the present invention provides the following technical solutions:

One of the technical solutions of the present invention is to provide a synthesis method of nickel-based metal-organic framework prepared by solvothermal synthesis method, which includes the following steps:

(1) Dissolve the metal salt in the organic solvent to obtain solution A;

(2) Dissolve the organic ligand in the organic solvent to obtain solution B;

(3) Add solution A and solution B into the reaction kettle to perform solvothermal reaction;

(4) Filter, wash and dry the solid product obtained from the reaction to obtain a nickel-based metal organic framework;

The metal salt includes nickel salt.

Preferably, the nickel salt is nickel nitrate and/or nickel chloride.

Preferably, the metal salt also contains cobalt salts and/or iron salts.

Preferably, the organic ligand includes terephthalic acid (H ₂ BDC), isophthalic acid (H ₃ BTC), and 2,5-dihydroxyterephthalic acid (H ₄ DOBDC).

Preferably, the molar ratio of metal ions to the organic ligand in the metal salt is 2:1.

Preferably, the temperature of the solvothermal reaction is 120-200°C and the time is 12-24 hours.

Preferably, the temperature of the solvothermal reaction is 140°C and the time is 24 hours.

Preferably, the organic solvent described in step (1) and step (2) is N,N-dimethylformamide (DMF).

The second technical solution of the present invention is to provide a nickel-based metal organic framework synthesized according to the above synthesis method.

The third technical solution of the present invention is to provide an application of the above-mentioned nickel-based metal-organic framework in electrode materials for batteries, capacitors or supercapacitors.

The beneficial technical effects of the present invention are as follows:

(1) The preparation method of the present invention is simple, low in cost and easy to produce in batches.

(2) The nickel metal organic framework prepared by the present invention has a large specific surface area (the specific surface area of the prepared product is in the range of 408.20~577.62m2 ^/ g), and has nanorods, lamellar nanoribbons, nanospheres, Nanosheets and other morphologies.

(3) The present invention alleviates the problem of insufficient structural stability of nickel-based metal organic framework materials caused by the hard and soft acid-base principle by introducing bimetals, improves the water stability of nickel-based metal organic frameworks, and greatly improves the material's use as a pseudocapacitive electrode material. cycle performance.

(4) The preparation method provided by the present invention successfully grows nickel-based metal-organic framework materials with a two-dimensional nanosheet structure, reducing the size of the bulk MOFs material to the nanosheet size, exposing more surface metal positions, thereby Generate more electrochemically active surface area, increase the specific capacitance of the material when charging and discharging as a pseudocapacitive electrode material, and improve the electrochemical performance of the material.

Description of the drawings

Figure 1 is an SEM pattern of the nickel-based MOF prepared in Examples 1-6 of the present invention, where a is the nickel-based MOF prepared in Example 1, b is the nickel-based MOF prepared in Example 2, and c is the nickel-based MOF prepared in Example 3. Nickel-based MOF, d is the nickel-based MOF prepared in Example 4, e is the nickel-based MOF prepared in Example 5, and f is the nickel-based MOF prepared in Example 6.

Figure 2 is an XRD pattern of the nickel-based MOF prepared in Examples 1-6 of the present invention.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention. It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention.

In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range, and any other stated value or value intermediate within a stated range, is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

Example 1

Weigh 4 mmol of nickel nitrate hexahydrate Ni(NO ₃ ) ₂ ·6H ₂ O, dissolve it in 15 mL of N,N-dimethylformamide (DMF), and conduct ultrasonic dissolution for 20 min to obtain green solution A; weigh 2 mmol of terephthalate Dissolve formic acid (H ₂ BDC) in 15 mL N, N-dimethylformamide (DMF), conduct ultrasonic dissolution for 20 minutes, and obtain a colorless and transparent solution B; mix A and B solutions and pour them into a 50 mL polytetrafluoroethylene high-pressure reactor. , put the reaction kettle into the oven, and react at 140°C for 24 hours. After the reaction, take out the reaction kettle and cool it to room temperature; use N,N-dimethylformamide (DMF) and deionized water to cool the resulting green solution. , anhydrous methanol, and dichloromethane were centrifuged and washed once each to leave the lower green powder; put the washed green powder into a vacuum drying box and dry it at 60°C for 12 hours to obtain a green powder, which is a nickel-based metal organic framework, recorded as Ni-BDC.

Mix Ni-BDC powder, acetylene black, and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of Ni-BDC obtained in Example 1 is shown in a in Figure 1. The material structure is a bulk structure composed of lamellar structures. The XRD pattern of the prepared Ni-BDC is shown in Figure 2. The characteristic peaks mainly appear near 8.50°, 14.99°, 15.88°, and 17.03°, which is consistent with the XRD pattern characteristics of Ni-MOF (PCPDF No. 35-1676).

Example 2

Weigh 4 mmol of nickel nitrate hexahydrate Ni(NO ₃ ) ₂ ·6H ₂ O, dissolve it in 15 mL of N,N-dimethylformamide (DMF), and perform ultrasonic dissolution for 20 min to obtain green solution A; weigh 2 mmol of phenylalanine Dissolve formic acid (H ₃ BTC) in 15mL N,N-dimethylformamide (DMF), perform ultrasonic dissolution for 20 minutes, and obtain a colorless and transparent solution B; mix A and B solutions and pour them into a 50mL polytetrafluoroethylene high-pressure reactor. , put the reaction kettle into the oven, and react at 140°C for 24 hours. After the reaction, take out the reaction kettle and cool it to room temperature; use N,N-dimethylformamide (DMF) and deionized water to cool the resulting green solution. , anhydrous methanol, and dichloromethane were centrifuged and washed once each to leave the lower green powder; put the washed green powder into a vacuum drying box and dry it at 60°C for 12 hours to obtain a green powder, which is a nickel-based metal organic framework, recorded as Ni-BTC.

Mix Ni-BTC powder, acetylene black, and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of Ni-BTC obtained in Example 2 is shown in b in Figure 1. The material structure is a rod-like structure composed of orderly stacking of lamellar structures. The XRD pattern of the prepared Ni-BTC is shown in Figure 2. The characteristic peaks mainly appear near 8.46°, 15.03°, 15.96°, and 17.07°, which is consistent with the XRD pattern characteristics of Ni-MOF (PCPDF No. 35-1676).

Example 3

Weigh 4 mmol of nickel nitrate hexahydrate Ni(NO ₃ ) ₂ ·6H ₂ O, dissolve it in 15 mL of N,N-dimethylformamide (DMF), and conduct ultrasonic dissolution for 20 min to obtain green solution A; weigh 2 mmol of 2,5- Dissolve dihydroxyterephthalic acid (H ₄ DOBDC) in 15mL N,N-dimethylformamide (DMF), conduct ultrasonic dissolution for 20 minutes, and obtain yellow solution B; mix A and B solutions and pour into 50mL polytetrafluoroethylene In the high-pressure reaction kettle, put the reaction kettle into the oven and react at 140°C for 24 hours. After the reaction is completed, take out the reaction kettle and cool it to room temperature; use N,N-dimethylformamide (DMF) in the resulting reddish-brown solution. , deionized water, anhydrous methanol, and methylene chloride were centrifuged and washed once each to leave the lower layer of turmeric powder; put the cleaned turmeric powder into a vacuum drying box and dry it at 60°C for 12 hours to obtain turmeric powder, which is nickel The base metal-organic framework is denoted as Ni-DOBDC.

Mix Ni-DOBDC powder, acetylene black, and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of Ni-DOBDC obtained in Example 3 is shown in c in Figure 1. The material structure is a spherical structure composed of fine lamellar structure. The XRD pattern of the prepared Ni-DOBDC is shown in Figure 2. The characteristic peaks mainly appear near 6.83° and 11.84°, which is consistent with the XRD pattern characteristics of MOF-74.

Example 4

Weigh 2 mmol of nickel nitrate hexahydrate Ni(NO ₃ ) ₂ ·6H ₂ O and 2 mmol of iron nitrate nonahydrate Fe(NO ₃ ) ₃ ·9H ₂ O, and dissolve them in 15 mL N,N-dimethylformamide (DMF). Perform ultrasonic dissolution for 20 minutes to obtain yellow solution A; weigh 2 mmol 2,5-dihydroxyterephthalic acid (H ₄ DOBDC) and dissolve it in 15 mL N,N-dimethylformamide (DMF), perform ultrasonic dissolution for 20 minutes, and obtain yellow solution A. Solution B; mix A and B solutions into a 50mL polytetrafluoroethylene high-pressure reactor, put the reactor into the oven, and react at 140°C for 24 hours. After the reaction is completed, take out the reactor and cool it to room temperature; remove the resulting brown solution Centrifuge and wash once with N,N-dimethylformamide (DMF), deionized water, anhydrous methanol, and dichloromethane respectively, leaving the lower green powder; put the washed reddish-brown powder into a vacuum drying box. After drying at 60°C for 12 hours, a reddish-brown powder was obtained, which was a nickel-based metal-organic framework, recorded as NiFe-DOBDC.

Mix NiFe-DOBDC powder, acetylene black, and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of the NiFe-DOBDC obtained in Example 4 is shown in d in Figure 1, showing a laminated block structure. The XRD pattern of the prepared NiFe-DOBDC is shown in Figure 2. The characteristic peaks mainly appear near 6.75° and 11.85°, which is consistent with the XRD pattern characteristics of MOF-74.

Example 5

Weigh 4 mmol of nickel chloride hexahydrate (NiCl ₂ ·6H ₂ O) and 2 mmol of cobalt nitrate hexahydrate Co(NO ₃ ) ₂ ·6H ₂ O, and dissolve them in 15 mL of N,N-dimethylformamide (DMF). Dissolve with ultrasonic for 20 minutes to obtain pink solution A; weigh 2 mmol of 2,5-dihydroxyterephthalic acid (H ₄ DOBDC) and dissolve it in 15 mL of N,N-dimethylformamide (DMF). Dissolve with ultrasonic for 20 minutes to obtain a yellow solution. B; Mix the A and B solutions into a 50mL polytetrafluoroethylene high-pressure reactor, put the reactor into the oven, and react at 140°C for 12 hours. After the reaction is completed, take out the reactor and cool it to room temperature; remove the resulting yellow-brown color The solution was centrifuged and washed once with N,N-dimethylformamide (DMF), deionized water, anhydrous methanol, and dichloromethane, leaving the lower layer of brown powder; put the washed brown powder into a vacuum drying box. Dry at 60°C for 12 hours to obtain a brown powder, which is a nickel-based metal-organic framework, recorded as NiCo-DOBDC.

Mix NiCo-DOBDC powder, acetylene black, and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of NiCo-DOBDC obtained in Example 5 is shown in e in Figure 1, which is a stacked lamellar structure. The XRD pattern of the prepared NiCo-DOBDC is shown in Figure 2. The characteristic peaks mainly appear near 6.87° and 11.85°, which is consistent with the XRD pattern characteristics of MOF-74.

Example 6

Weigh 2mmol nickel chloride hexahydrate (NiCl ₂ ·6H ₂ O), 1mmol iron nitrate nonahydrate Fe(NO ₃ ) ₃ ·9H ₂ O, and 1mmol cobalt nitrate hexahydrate Co(NO ₃ ) ₂ ·6H ₂ O, and dissolve In 15mL N,N-dimethylformamide (DMF), perform ultrasonic dissolution for 20 minutes to obtain reddish brown solution A; weigh 2mmol 2,5-dihydroxyterephthalic acid (H ₄ DOBDC) and dissolve it in 15mLN,N-dimethylformamide. In methylformamide (DMF), conduct ultrasonic dissolution for 20 minutes to obtain yellow solution B; mix A and B solutions and pour them into a 50mL polytetrafluoroethylene high-pressure reaction kettle, put the reaction kettle into an oven, and react at 140°C for 12 hours. After the reaction, the reaction kettle was taken out and cooled to room temperature; the obtained dark brown solution was centrifuged and washed once with N,N-dimethylformamide (DMF), deionized water, anhydrous methanol, and dichloromethane respectively, leaving Remove the dark brown powder from the lower layer; put the cleaned dark brown powder into a vacuum drying box and dry it at 60°C for 12 hours to obtain a dark brown powder, which is a nickel-based metal organic framework, recorded as NiCoFe-DOBDC.

Mix NiCoFe-DOBDC powder, acetylene black, and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1, drop an appropriate amount of absolute ethanol into the mortar, and grind thoroughly to obtain a uniform black slurry. Apply the black electrode slurry evenly on the washed and dried nickel foam, and place it in a vacuum drying oven to dry at 50°C for 24 hours to obtain an electrode sheet. The prepared electrode sheet was used as a working electrode, placed in a three-electrode system with a platinum wire counter electrode and an Ag/AgCl reference electrode, and an electrochemical workstation was used for electrochemical performance testing.

The SEM pattern of NiCoFe-DOBDC obtained in Example 6 is shown in f in Figure 1, which is a lamellar structure. The XRD pattern of the prepared NiCoFe-DOBDC is shown in Figure 2. The characteristic peaks mainly appear near 6.83° and 11.83°, which is consistent with the XRD pattern characteristics of MOF-74.

Detection example

The electrode materials prepared in Examples 1-6 were subjected to electrical performance tests in a three-electrode system of 4MKOH, including GCD, EIS, CV and cycle stability. The specific capacitance was calculated based on the fitted GCD, EIS, and CV measurement data. The results are shown in Table 1, and the cycle stability test results are shown in Table 2.

Table 1. Specific capacitance of each electrode material at current densities of 1, 2, 5, 8, and 10A/g.

Table 2. Specific capacitance retention rate of each electrode material after 3000 cycles at a current density of 10A/g.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 efficiency 56.34% 50.61% 50.68% 83.59% 84.79% 89.92%

In summary, the present invention provides a nickel-based metal-organic framework material prepared based on a one-step solvothermal synthesis method. By further doping bimetals, the synthesis conditions are changed, the morphology and structure of the material are adjusted, and the water stability and electrical stability of the material are improved. chemical properties. The material synthesis method is simple, the use of instruments and reagents is simple, and less acid and alkali waste liquid is produced. The successfully synthesized nanosheet structure has greatly improved the shortcomings of insufficient electrochemical performance of bulk nickel-based metal-organic frameworks, greatly improved the cycle performance of the material when used as a pseudocapacitive electrode material, and provided a good foundation for the application of nickel-based metal-organic frameworks. Provide basic research support on pseudocapacitive electrode materials.

The above-described embodiments only describe the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (6)

1. The synthesis method of the nickel-based metal organic framework prepared on the basis of the solvothermal synthesis method is characterized by comprising the following steps of:

(1) Dissolving metal salt in an organic solvent to obtain a solution A;

(2) Dissolving an organic ligand in an organic solvent to obtain a solution B;

(3) Adding the solution A and the solution B into a reaction kettle for solvothermal reaction;

(4) Filtering, washing and drying a solid product obtained by the reaction to obtain a nickel-based metal organic framework;

the metal salt is nickel salt, cobalt salt and ferric salt;

the organic ligand is 2, 5-dihydroxyterephthalic acid;

the molar ratio of the metal ions in the metal salt to the organic ligand is 2:1.

2. The synthesis according to claim 1, wherein the nickel salt is nickel nitrate and/or nickel chloride.

3. The method according to any one of claims 1 to 2, wherein the solvothermal reaction is carried out at a temperature of 120 to 200 ℃ for a period of 12 to 24 hours.

4. The synthesis method according to any one of claims 1 to 2, wherein the organic solvent in step (1) and step (2) is N, N-dimethylformamide.

5. The nickel-based metal organic framework synthesized by the synthesis method according to any one of claims 1 to 4.

6. The use of the nickel-based metal organic framework according to claim 5 in electrode materials of batteries, capacitors or supercapacitors.