N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material and preparation method

Abstract

This invention provides an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material and its preparation method. Ni and Co sources are mixed and added to a solvent, and stirred to obtain solution A. 4,4'-stilbene dicarboxylic acid and 2,2'-bipyridine are dissolved in a solvent and stirred to obtain solution B. Solution B is added dropwise to solution A under stirring to obtain a conductive MOF precursor solution C. MoS2 is added to DMF, and after ultrasonic treatment, the supernatant is collected by centrifugation to obtain a sheet-like two-dimensional MoS2DMF dispersion D. The conductive MOF precursor solution C is added to the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate under stirring, followed by the dropwise addition of the sheet-like two-dimensional MoS2DMF dispersion D. After stirring until homogeneous, a hydrothermal reaction is performed to obtain a sample. The sample is repeatedly washed with ethanol several times and then vacuum dried to obtain the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material.

Description

Technical Field

[0001] This invention relates to the field of electrochemical electrode material preparation technology, specifically to an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material and its preparation method. Background Technology

[0002] Supercapacitors, as a novel and highly efficient energy storage device, possess the discharge power of traditional capacitors and the charge storage capacity of chemical batteries. Compared with other new energy storage devices, they feature high instantaneous power, rapid charge and discharge, and long cycle life, showing broad application prospects in the power industry, rail transportation, new energy vehicles, industrial control, wind and solar power generation, and military fields. However, supercapacitors currently suffer from disadvantages such as high cost and low energy density, limiting their further widespread application. Current research on improving supercapacitor performance mainly focuses on developing high-performance novel electrode materials.

[0003] Metal-organic frameworks (MOFs) hold significant research value in the field of electrode materials due to their unique structural tunability, porosity, and topological diversity. However, MOFs suffer from relatively poor stability and conductivity, and are easily affected by environmental conditions such as temperature and humidity, leading to structural changes that consequently impact their electrochemical performance. This limits their application in supercapacitors. To improve MOF performance, researchers have explored various methods, such as doping and composite methods. Among these, N and B co-doping is an effective way to improve the conductivity and capacitance of MOFs. However, maintaining the conductivity and high capacitance of MOFs while achieving stability as an electrode material is of great importance in practical applications.

[0004] Molybdenum disulfide (MoS2), due to its unique two-dimensional material structure, can store more charge, providing a higher energy density for supercapacitors compared to traditional activated carbon materials. Simultaneously, its relatively stable structure, resistant to significant structural changes, helps maintain the long-term stability and reliability of supercapacitors. However, MoS2's poor conductivity and low ion transport rate can affect the charge-discharge efficiency and performance of supercapacitors. Summary of the Invention

[0005] The purpose of this invention is to provide an N / B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material and its preparation method, overcoming the problems of low conductivity, low stability, and small specific capacity of existing electrode materials. This invention first synthesizes a bimetallic conductive MOF with excellent conductivity, then enhances the conductivity of the MOF through N / B co-doping, while introducing more redox active sites to provide additional charge storage, thereby increasing the specific capacity. The combination with MoS2 further enhances the ion transport rate.

[0006] This invention is achieved through the following technical solution:

[0007] The preparation method of N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material includes the following steps:

[0008] (1) Take Ni source and Co source and add them to the solvent. Stir to obtain solution A; take 4,4'-stilbene dicarboxylic acid and 2,2'-bipyridine and dissolve them in the solvent. Stir to obtain solution B. Add solution B dropwise to solution A under stirring conditions to obtain conductive MOF precursor solution C.

[0009] (2) MoS2 was added to DMF, and after ultrasonic treatment, the supernatant was collected by centrifugation to obtain a two-dimensional MoS2 DMF dispersion D;

[0010] (3) Add the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate to the conductive MOF precursor solution C obtained in step (1) under stirring conditions, and add the sheet-like two-dimensional MoS2 DMF dispersion D obtained in step (2) dropwise. After stirring evenly, perform hydrothermal reaction at 80-200℃ for 12-24 hours to obtain the sample. Wash the sample repeatedly with ethanol several times and vacuum dry to obtain N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material.

[0011] Furthermore, the Ni source is Ni(SO3NH2)2;

[0012] The Co source is Co(SO3NH2)2.

[0013] Further, the solvent mentioned in step (1) is DMF.

[0014] Furthermore, during the preparation of solution A, 6-12 mg of Ni source and 6-12 mg of Co source are added to every 5-10 mL of solvent;

[0015] In the preparation of solution B, 0.1-0.2 g of 4,4'-stilbene dicarboxylic acid and 10-20 mg of 2,2'-bipyridine are added to every 10-20 mL of solvent.

[0016] During the process of adding solution B to solution A, the volume ratio of solvent in solution A to solvent in solution B is (5-10):(10-20).

[0017] Furthermore, in step (2), 1g of MoS2 is added to every 100mL of DMF, and the size of MoS2 is <2μm.

[0018] Furthermore, in step (2), the ultrasonic process is maintained in an ice-water bath for 2-6 hours, and the centrifugation speed is 2000-8000 rpm / min.

[0019] Further, in step (3), the volume ratio between the conductive MOF precursor solution C, the ionic liquid, and the sheet-like two-dimensional MoS2 DMF dispersion D is (15-30):(0.5-6):(10-15).

[0020] The N and B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material was prepared using the method described above.

[0021] Furthermore, the surface of the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material has a loose porous structure, and the square rod-shaped bimetallic conductive MOF is loaded on the MoS2 sheet.

[0022] Furthermore, the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material exhibits a specific capacitance of 1000-1200 F / g when charged and discharged in the range of 0-0.4V at a current density of 1A / g.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The method of this invention successfully prepared a high-performance N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material. This material exhibits high energy density, power density, and cycle life, making it suitable for the fabrication of high-performance supercapacitors. Compared with existing technologies, the preparation method of this invention is simple and easy to implement, uses widely available raw materials, and has broad application prospects. Specifically:

[0025] (1) The preparation process is simple. The conductive bimetallic MOF load is grown on the MOS2 layer by a one-step solvothermal method, which improves the conductivity of MOS2 and improves the poor stability of MOF structure.

[0026] (2) A three-dimensional framework structure was constructed using H2SDC with a highly conjugated structure as the main ligand and BPY as the auxiliary ligand, along with Co(SO3NH2)2 and Ni(SO3NH2)2 to provide highly redox-active cobalt-nickel bimetallic nodes, thereby enhancing the bond charge transport capability of the MOF material. At the same time, the Co and Ni nodes provide dense active sites for the rapid pseudocapacitive reaction.

[0027] (3) The unique cation and anion structure of the ionic liquid [BMIM]BF4 promotes the stability of MOF synthesis during the solvothermal process. At the same time, B and N doping was carried out in the porous structure of MOF and the sheet structure of MoS2, which increased the pseudocapacitance and significantly improved the charge storage capacity, with a specific capacity of 1000-1200 F / g. The doping of B and N further improved the conductivity of MOF / MoS2. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. The following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 The image shows the SEM images of the N and B co-doped bimetallic conductive MOF / MoS2 in Example 1, where (a) shows the loose porous structure on the surface of the composite material; and (b) shows the N and B co-doped conductive MOF loaded with MoS2 sheets.

[0030] Figure 2 This is a SEM image of the N and B co-doped bimetallic conductive MOF in the composite material of Example 1;

[0031] Figure 3 The charge-discharge curve at 1 A / g is shown in Example 1 when the N, B co-doped bimetallic conductive MOF / MoS2 composite material was used as the electrode material for a supercapacitor. Detailed Implementation

[0032] The present invention will now be described in detail:

[0033] A method for preparing an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material includes the following steps:

[0034] (1) Preparation of bimetallic conductive MOF: First, 6-12 mg of nickel sulfamate (Ni(SO3NH2)2)2 and 6-12 mg of cobalt sulfamate (Co(SO3NH2)2)2 were mixed and added to 5-10 mL of N-methylpyrrolidone (DMF), and the mixture was stirred magnetically to obtain solution A. Then, 0.1-0.2 g of 4,4'-stilbene dicarboxylic acid (H2SDC) and 10-20 mg of 2,2'-bipyridine (BPY) were dissolved in 10-20 mL of DMF, and the mixture was stirred magnetically to obtain solution B. Then, solution B was added dropwise to solution A under magnetic stirring to obtain conductive MOF precursor solution C.

[0035] (2) Exfoliation of two-dimensional MoS2 nanosheets: Take 1g of MoS2 and add it to 100mL of DMF solution, sonicate for 2-6 hours, then centrifuge and take the upper layer liquid as the two-dimensional MoS2 DMF dispersion D;

[0036] MoS2 is a commercially available material with a size of <2μm. The ultrasonic process is carried out in an ice-water bath, using an ultrasonic cell disruptor and a centrifuge speed of 2000-8000 rpm / min.

[0037] (3) Preparation of N, B co-doped bimetallic conductive MOF / MoS2: The conductive MOF precursor solution C prepared in step (1) is added to 0.5-6 mL of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) under magnetic stirring. Then, 10-15 mL of the sheet-like two-dimensional MoS2 DMF dispersion D prepared in step (2) is added dropwise. After stirring evenly, the mixture is sealed in a reaction vessel and hydrothermally reacted at 80-200℃ for 12-24 hours to obtain the sample. Finally, the sample is washed repeatedly with ethanol 3-5 times and dried under vacuum to obtain the N, B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material.

[0038] The reactor is a stainless steel reactor with a 20-50mL Teflon lining.

[0039] A bimetallic conductive MOF / MoS2 material co-doped with N and B has a loose porous structure on its surface. The bimetallic conductive MOF with a square rod structure is loaded on the MoS2 sheet. When charged and discharged in the range of 0-0.4V, the specific capacitance is 1000-1200F / g at a current density of 1A / g.

[0040] The embodiments of the present invention will be described in detail below with reference to the examples. These embodiments represent preferred solutions of the present invention and should not be construed as limiting the scope of the invention. Unless otherwise specified, the methods and experimental equipment used in the following embodiments are conventional methods and instruments.

[0041] Example 1

[0042] A method for preparing an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material includes the following steps:

[0043] (1) Preparation of bimetallic conductive MOF: First, 6 mg of Ni(SO3NH2)2 and 6 mg of Co(SO3NH2)2 were mixed and added to 10 mL of DMF solution, and the mixture was stirred magnetically to obtain solution A. Then, 0.1 g of H2SDC and 10 mg of BPY were dissolved in 20 mL of DMF solution and stirred magnetically to obtain solution B. Then, solution B was added dropwise to solution A under magnetic stirring to obtain conductive MOF precursor solution C.

[0044] (2) Exfoliation of two-dimensional MoS2 nanosheets: Take 1g of MoS2 and add it to 100mL of DMF solution. Use an ultrasonic cell disruptor to sonicate for 2 hours. Then, centrifuge at 2000rpm / min and take the upper layer liquid as DMF dispersion of two-dimensional MoS2 sheets.

[0045] (3) Preparation of N, B co-doped bimetallic conductive MOF / MoS2: The conductive MOF precursor solution C prepared in step (1) was added to 0.5 mL of ionic liquid ([BMIM]BF4) under magnetic stirring. Then, 10 mL of the sheet-like two-dimensional MoS2DMF dispersion D prepared in step (2) was added dropwise. After stirring evenly, the mixture was sealed in a reaction vessel and hydrothermally reacted at 200 °C for 12 hours to obtain the sample. Finally, the sample was washed three times with ethanol and dried under vacuum.

[0046] (4) The application of N and B co-doped bimetallic conductive MOF / MoS2 as a supercapacitor electrode material, with a specific capacitance of 1185.4 F / g at a current density of 1 A / g during charging and discharging in the range of 0-0.4V.

[0047] from Figure 1 It can be seen that (a) the composite material surface has a loose and porous structure, and (b) the N and B co-doped conductive MOF supports MoS2 sheets; from Figure 2 It can be seen that the synthesized N, B co-doped bimetallic conductive MOF has a rod-like structure; from Figure 3 It can be seen that the electrode material used in supercapacitors has excellent specific capacitance.

[0048] Example 2

[0049] A method for preparing an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material includes the following steps:

[0050] (1) Preparation of bimetallic conductive MOF: First, 12 mg of Ni(SO3NH2)2 and 12 mg of Co(SO3NH2)2 were mixed and added to 10 mL of DMF solution, and the mixture was stirred magnetically to obtain solution A. Then, 0.2 g of H2SDC and 20 mg of BPY were dissolved in 20 mL of DMF and stirred magnetically to obtain solution B. Then, solution B was added dropwise to solution A under magnetic stirring to obtain conductive MOF precursor solution C.

[0051] (2) Exfoliation of two-dimensional MoS2 nanosheets: 1g of MoS2 was added to 100mL of DMF solution and sonicated for 3 hours using an ultrasonic cell disruptor. The upper layer was then taken as the two-dimensional MoS2 DMF dispersion D by centrifuging at 8000rpm / min.

[0052] (3) Preparation of N, B co-doped bimetallic conductive MOF / MoS2: The conductive MOF precursor solution C prepared in step (1) was added to 6 mL of ionic liquid [BMIM]BF4 under magnetic stirring. Then, 15 mL of the sheet-like two-dimensional MoS2 DMF dispersion D prepared in step (2) was added dropwise. After stirring evenly, the mixture was sealed in a reaction vessel and hydrothermally reacted at 80 °C for 24 hours to obtain the sample. Finally, the sample was washed five times with ethanol and dried under vacuum.

[0053] (4) The application of N and B co-doped bimetallic conductive MOF / MoS2 as a supercapacitor electrode material, the electrochemical test shows that the charge and discharge range is 0-0.4V, and the specific capacitance is 1032.3F / g at a current density of 1A / g.

[0054] Example 3

[0055] A method for preparing an N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material includes the following steps:

[0056] (1) Preparation of bimetallic conductive MOF: First, 12 mg Ni(SO3NH2)2 and 6 mg Co(SO3NH2)2 were mixed and added to 10 mL of DMF solution, and the mixture was stirred magnetically to obtain solution A. Then, 0.2 g of 4H2SDC and 10 mg of BPY were dissolved in 10 mL of DMF and stirred magnetically to obtain solution B. Then, solution B was added dropwise to solution A under magnetic stirring to obtain conductive MOF precursor solution C.

[0057] (2) Exfoliation of two-dimensional MoS2 nanosheets: 1g of MoS2 was added to 100mL of DMF solution and sonicated for 6 hours using an ultrasonic cell disruptor. The upper layer was taken as the two-dimensional MoS2 DMF dispersion D by centrifuging at 2000rpm / min.

[0058] (3) Preparation of N, B co-doped bimetallic conductive MOF / MoS2: The conductive MOF precursor solution C prepared in step (1) was added to 6 mL of ionic liquid [BMIM]BF4 under magnetic stirring. Then, 10 mL of the sheet-like two-dimensional MoS2 DMF dispersion D prepared in step (2) was added dropwise. After stirring evenly, the mixture was sealed in a reaction vessel and hydrothermally reacted at 200 °C for 24 hours to obtain the sample. Finally, the sample was washed three times with ethanol and dried under vacuum.

[0059] (4) The application of N and B co-doped bimetallic conductive MOF / MoS2 as a supercapacitor electrode material: electrochemical tests showed that the specific capacitance was 1127.8 F / g under a current density of 1 A / g during charge and discharge in the range of 0-0.4 V.

[0060] Comparative Example 1

[0061] Chinese invention patent CN106057498B discloses a MoS2 supercapacitor electrode material, with a specific capacitance of 307 F / g measured at 1 A / g.

[0062] Comparative Example 2

[0063] Chinese invention patent CN110504110B discloses an electrode material for MOF supercapacitors, with a specific capacitance of 332.8 F / g measured at 1 A / g.

[0064] Table 1 Comparison of specific capacity performance between embodiments of the present invention and comparative examples.

[0065]

[0066] The data listed in Table 1 show that, compared with the comparative examples and embodiments, the specific capacity of the embodiments of the present invention is increased by more than 3 times.

[0067] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material, characterized in that, Includes the following steps: (1) Take Ni source and Co source and add them to the solvent. Stir to obtain solution A; take 4,4'-stilbene dicarboxylic acid and 2,2'-bipyridine and dissolve them in the solvent. Stir to obtain solution B. Add solution B dropwise to solution A under stirring conditions to obtain conductive MOF precursor solution C. (2) MoS2 was added to DMF, and after ultrasonic treatment, the supernatant was collected by centrifugation to obtain a two-dimensional MoS2 DMF dispersion D; (3) Add the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate to the conductive MOF precursor solution C obtained in step (1) under stirring conditions, and add the sheet-like two-dimensional MoS2 DMF dispersion D obtained in step (2) dropwise. After stirring evenly, perform hydrothermal reaction at 80-200℃ for 12-24 hours to obtain the sample. Wash the sample repeatedly with ethanol several times and vacuum dry to obtain N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material.

2. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, The Ni source is Ni(SO3NH2)2; The Co source is Co(SO3NH2)2.

3. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, The solvent mentioned in step (1) is DMF.

4. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, In the process of preparing solution A, 6-12 mg of Ni source and 6-12 mg of Co source are added to every 5-10 mL of solvent; In the preparation of solution B, 0.1-0.2 g of 4,4'-stilbene dicarboxylic acid and 10-20 mg of 2,2'-bipyridine are added to every 10-20 mL of solvent. During the process of adding solution B to solution A, the volume ratio of solvent in solution A to solvent in solution B is (5-10):(10-20).

5. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, In step (2), 1g of MoS2 is added to every 100mL of DMF. The size of MoS2 is <2μm.

6. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, In step (2), the ultrasonic process is maintained in an ice-water bath for 2-6 hours, and the centrifugation speed is 2000-8000 rpm / min.

7. The method for preparing the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 1, characterized in that, In step (3), the volume ratio between the conductive MOF precursor solution C, the ionic liquid, and the sheet-like two-dimensional MoS2 DMF dispersion D is (15-30):(0.5-6):(10-15).

8. N, B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The N, B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 8, characterized in that, The surface of the N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material has a loose porous structure, and the square rod-shaped bimetallic conductive MOF is loaded on the MoS2 sheet.

10. The N, B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material according to claim 8, characterized in that, The N,B co-doped bimetallic conductive MOF / MoS2 supercapacitor electrode material exhibits a specific capacitance of 1000-1200 F / g when charged and discharged within the range of 0-0.4V at a current density of 1A / g.

Images