A MOFs / GO / CC composite material, its preparation method and application

Abstract

This invention relates to the field of MOFs composite materials technology, and discloses a MOFs / GO / CC composite material, its preparation method, and its applications. The method uses carbon cloth as the working electrode and graphene source, and sulfate as the electrolyte. Graphene oxide is prepared by electrochemically exfoliating carbon. During the exfoliation process, the edges and basal surfaces of the carbon cloth are oxidized, introducing oxygen-containing functional groups. Then, using 1 / 4-tetra(4-carboxyphenyl)porphyrin as an organic ligand, Co-TCPP is grown in situ on the graphene-modified carbon cloth electrode surface via a solvothermal method. This preparation process is green and environmentally friendly, and the resulting MOFs / GO / CC composite material overcomes the shortcomings of carbon cloth as an electrode material in supercapacitors, namely poor energy storage performance and low surface activity.

Description

Technical Field

[0001] This invention relates to the field of MOF composite materials technology, specifically to a MOFs / GO / CC composite material, its preparation method, and its application. Background Technology

[0002] Currently, the fabrication of carbon cloth-based flexible electrodes often requires strong oxidants. In contrast, introducing graphene into carbon cloth is a more effective strategy for improving capacitance performance. However, current methods for preparing graphene also require hazardous reagents such as concentrated sulfuric acid and potassium permanganate, posing significant challenges for large-scale production. Furthermore, the incompatibility between pseudocapacitive materials and carbon cloth in carbon cloth-based composites leads to poor performance in the final composite material.

[0003] Two-dimensional conjugated metal-organic frameworks (2D c-MOFs), as an emerging class of conductive metal-organic framework materials, have attracted much attention due to their efficient in-plane conjugation and strong interlayer coupling characteristics, showing broad application prospects. Although the conductivity of 2D conductive MOFs has been improved compared with traditional MOF materials, its conductivity is still at a relatively low level compared with traditional metallic conductors and some high-performance conductive materials.

[0004] Therefore, it is necessary to use green and safe methods to electrochemically modify carbon cloth and use it as a substrate to composite with highly electrochemically active two-dimensional conjugated MOFs materials to prepare a MOFs / graphene / carbon cloth composite material with excellent electrochemical performance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a MOFs / GO / CC composite material, its preparation method, and its applications. This invention utilizes an electrochemical method to prepare GO in situ at room temperature and pressure, completely avoiding the traditional Hummers method (which uses strong oxidants and strong acids such as potassium permanganate and concentrated sulfuric acid) for GO preparation. This method is an environmentally friendly synthesis strategy. This invention directly grows active materials on electrochemically exfoliated carbon cloth, forming an integrated structure of "current collector-conductive layer (GO)-active material (MOF)". The components are connected by chemical bonds (coordination bonds, etc.), resulting in strong bonding and smooth electron transport paths, effectively preventing the shedding of active material during cycling and solving the inherent defects of carbon cloth electrodes. This invention specifically compensates for the shortcomings of carbon cloth as an electrode material, namely "low energy storage performance and low surface activity". By generating GO and growing MOFs in situ, its specific surface area and electrochemical active sites are greatly increased, transforming it from an ordinary current collector into a high-performance electrode.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing MOFs / GO / CC composite materials includes the following steps:

[0008] Step (1): Ultrasonically wash the carbon cloth and dry it to obtain the washed carbon cloth;

[0009] The washed carbon cloth was electrochemically peeled off using an electrochemical method. After peeling, it was taken out, washed, and dried to obtain the GO / CC composite material.

[0010] Step (2): Place the GO / CC composite material in a mixed solution of TCPP (medium-tetra(4-carboxyphenyl)porphyrin), PVP (polyvinylpyrrolidone) and Co(NO3)2•6H2O, and react it using a one-step hydrothermal method. After the reaction is completed, remove the material to obtain the MOFs / GO / CC composite material.

[0011] Preferably, in step (1), the ultrasonic washing operation includes: ultrasonically washing the carbon cloth with acetone, ethanol and water in sequence for 25-30 minutes.

[0012] Preferably, in step (1), the electrochemical stripping operation includes: connecting the washed carbon cloth to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode; immersing the three electrodes in the electrolyte; applying a constant voltage of +1.5~+2.5 V between the washed carbon cloth and the platinum sheet electrode; and performing electrochemical stripping for 10~12 min.

[0013] Furthermore, the electrolyte is a 0.65~0.75 mol / L Na2SO4 aqueous solution.

[0014] Preferably, in step (2): the solid-liquid ratio of the GO / CC composite material to the mixed solution of 1g:150mL~160mL is 1g:150mL~160mL; the mixed solution of TCPP (1g:150mL~160mL) of 1g:150mL~160mL is prepared by mixing the mixed solution of 1g:150mL~160mL of 1g:150mL~160mL of 160mL;

[0015] The mixture of methyl-tetra(4-carboxyphenyl)porphyrin is prepared by the following steps: dissolving 8-10 mg of methyl-tetra(4-carboxyphenyl)porphyrin and 15-20 mg of polyvinylpyrrolidone in 10-12 mL of mixed solvent and stirring until homogeneous.

[0016] The Co(NO3)2•6H2O solution is prepared by the following steps: dissolving 0.0180~0.0185g of Co(NO3)2•6H2O in 4~6mL of mixed solvent and sonicating for 5~10min;

[0017] The above-mentioned mixed solvents were all prepared by mixing N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to 3:1.3.

[0018] Preferably, in step (2), the one-step hydrothermal method includes: using a mixture of methyl-tetra(4-carboxyphenyl)porphyrin as solution A and Co(NO3)2•6H2O solution as solution B; placing the GO / CC composite material in solution B and sonicating it for 20-30 min; then pouring the GO / CC composite material and solution B together into solution A and stirring for 10-15 min; transferring the mixture of solution A and solution B and the GO / CC composite material together into a high-pressure reactor and reacting it at 110-140℃ for 10-12 h.

[0019] Preferably, a MOFs / GO / CC composite material is prepared using the MOFs / GO / CC composite material preparation method described above.

[0020] Preferably, an application of the MOFs / GO / CC composite material as described above in the field of electrochemical energy storage.

[0021] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0022] This invention provides a method for preparing graphene-modified carbon cloth electrodes by mild electrochemical exfoliation of carbon. The method uses carbon cloth as the working electrode and graphene source, and sulfate as the electrolyte. Graphene oxide material is prepared by electrochemically exfoliating carbon. During the exfoliation process, the edges and basal surfaces of the carbon cloth are oxidized, introducing oxygen-containing functional groups such as -COOH, -OH, and C=O. These functional groups are metal ions (M... + It provides specific anchoring points, and metal ions can be pre-adsorbed on the graphene surface through coordination, providing "seeds" for the heterogeneous nucleation of MOFs; and the presence of the graphene layer on the carbon cloth surface significantly increases the surface area of ​​the carbon cloth and improves the hydrophilicity and electrochemical activity of the carbon cloth.

[0023] This invention utilizes a hydrothermal method to in-situ grow Co-TCPP on the surface of a graphene-modified carbon cloth electrode using neu-tetra(4-carboxyphenyl)porphyrin as an organic ligand, constructing a GO / MOF composite material. The high conductivity of graphene compensates for the poor conductivity of most MOF materials, while the porosity and high activity of MOFs enrich the functionality of graphene. Graphene oxide, as an intermediate layer, significantly optimizes the electronic conduction pathway and mass transport channels of Co-TCPP, while also generating a synergistic effect with Co-TCPP.

[0024] The MOFs / GO / CC composite material synthesized in this invention using an electrochemical exfoliation-hydrothermal method exhibits a strength of 2705 mF / cm². 2 The composite material has high specific capacitance and long cycle life, and the manufacturing process is green and environmentally friendly. It makes up for the shortcomings of carbon cloth as an electrode material of supercapacitors, such as poor energy storage performance and low surface activity. This opens up a new route for the application of pseudocapacitive supercapacitors in the field of energy storage. Attached Figure Description

[0025] Figure 1 The images show the (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP / GO / CC-110 composite material prepared in Example 1 of this invention under different current densities during energy storage performance testing.

[0026] Figure 2 The images show (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP / GO / CC-120 composite material prepared in Example 2 of this invention under different current densities during energy storage performance testing.

[0027] Figure 3 The images show (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP / GO / CC-130 composite material prepared in Example 3 of this invention under different current densities during energy storage performance testing.

[0028] Figure 4 The images show the (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP / GO / CC-140 composite material prepared in Example 4 of this invention under different current densities during energy storage performance testing.

[0029] Figure 5 The images show the (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP@GO / CC composite material prepared in Comparative Example 1 of this invention in energy storage performance testing at different current densities.

[0030] Figure 6The figures show (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-TCPP / CC composite material prepared in Comparative Example 2 of this invention at different current densities during energy storage performance testing.

[0031] Figure 7 The images show the (a) constant current charge-discharge (CP) curves and (b) specific capacitance curves of the Co-BTB / GO / CC composite material prepared in Comparative Example 3 of this invention in energy storage performance testing at different current densities.

[0032] Figure 8 This is a comparison of the cyclic voltammetry (CV) curves of the materials prepared in Example 3 of the present invention with those in Comparative Examples 4 and 5 at a scan rate of 5 mV / s.

[0033] Figure 9 These are scanning electron microscope (SEM) images of the materials prepared in Example 3, Comparative Examples 4 and 5 of the present invention; (a) is an SEM image of the untreated carbon cloth CC in Comparative Example 5; (b) is an SEM image of the carbon cloth GO / CC composite material after electrochemical exfoliation in Comparative Example 4; (c) and (d) are both SEM images of the Co-TCPP / GO / CC-130 composite material prepared in Example 3, wherein (c) is an SEM image at 20 μm and (d) is an SEM image at a 5 μm scale. Detailed Implementation

[0034] The present invention will be further illustrated below through specific embodiments. The following embodiments are specific implementations of the present invention, but the implementation of the present invention is not limited to the following embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

[0035] Example 1

[0036] This embodiment discloses a method for preparing MOFs / GO / CC composite materials, including the following steps:

[0037] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0038] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0039] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0040] The GO / CC composite material was placed in solution B and sonicated for 30 min. Then, the GO / CC composite material and solution B were poured into solution A and stirred for 10 min. The mixture of solution A and solution B and the GO / CC composite material were transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 110 °C for 12 h. After the reaction was completed, the material was removed, rinsed three times each with ethanol and deionized water, and dried at 60 °C to obtain the MOFs / GO / CC composite material, denoted as Co-TCPP / GO / CC-110.

[0041] Example 2

[0042] This embodiment discloses a method for preparing MOFs / GO / CC composite materials, including the following steps:

[0043] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0044] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0045] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0046] The GO / CC composite material was placed in solution B and sonicated for 30 min. Then, the GO / CC composite material and solution B were poured into solution A and stirred for 10 min. The mixture of solution A and solution B and the GO / CC composite material were transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 120°C for 12 h. After the reaction was completed, the material was removed, rinsed three times each with ethanol and deionized water, and dried at 60°C to obtain the MOFs / GO / CC composite material, denoted as Co-TCPP / GO / CC-120.

[0047] Example 3

[0048] This embodiment discloses a method for preparing MOFs / GO / CC composite materials, including the following steps:

[0049] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0050] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0051] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0052] The GO / CC composite material was placed in solution B and sonicated for 30 min. Then, the GO / CC composite material and solution B were poured into solution A and stirred for 10 min. The mixture of solution A and solution B and the GO / CC composite material were transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 130 °C for 12 h. After the reaction was completed, the material was removed, rinsed three times each with ethanol and deionized water, and dried at 60 °C to obtain the MOFs / GO / CC composite material, denoted as Co-TCPP / GO / CC-130.

[0053] Example 4

[0054] This embodiment discloses a method for preparing MOFs / GO / CC composite materials, including the following steps:

[0055] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0056] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0057] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0058] The GO / CC composite material was placed in solution B and sonicated for 30 min. Then, the GO / CC composite material and solution B were poured into solution A and stirred for 10 min. The mixture of solution A and solution B and the GO / CC composite material were transferred to a polytetrafluoroethylene-lined high-pressure reactor and reacted at 140 °C for 12 h. After the reaction was completed, the material was removed, rinsed three times each with ethanol and deionized water, and dried at 60 °C to obtain the MOFs / GO / CC composite material, denoted as Co-TCPP / GO / CC-140.

[0059] Comparative Example 1

[0060] This comparative example discloses a method for preparing Co-TCPP@GO / CC composite material, including the following steps:

[0061] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0062] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0063] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0064] Solution B was poured into solution A and stirred for 10 minutes. The mixture of solution A and solution B was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 130°C for 12 hours. After the reaction was completed, the mixture was removed to obtain Co-TCPP material.

[0065] 4 mg of Co-TCPP material, 1 mg of acetylene black powder, and 1 mg of PVDF binder were mixed and ground for 30 min, and then dispersed in 1~1.5 mL of NMP (N-methylpyrrolidone) to obtain Co-TCPP material slurry;

[0066] Using GO / CC composite material as a substrate, Co-TCPP material slurry was uniformly coated onto GO / CC composite material at a coating amount of 2-3 mg. After coating, the material was dried, washed with ethanol and water, and dried again at 60℃ for 12 h to obtain Co-TCPP@GO / CC composite material, denoted as Co-TCPP@GO / CC.

[0067] Comparative Example 2

[0068] This comparative example discloses a method for preparing Co-TCPP / CC composite material, including the following steps:

[0069] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0070] The washed carbon cloth was placed in a mixed solution of 98% concentrated sulfuric acid and 68% concentrated nitric acid in a volume ratio of 3:1 and reacted at 100°C for 12 hours. After the reaction was completed, the cloth was removed, rinsed with deionized water 3 to 5 times, and then dried at 60°C to obtain the pretreated carbon cloth.

[0071] Step (2): Dissolve 10 mg of TCPP (medium-tetra(4-carboxyphenyl)porphyrin) and 20 mg of PVP (polyvinylpyrrolidone) in 12 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), stir well to obtain solution A; dissolve 0.0182 g of Co(NO3)2•6H2O in 4 mL of a mixed solvent (DMF and ethanol in a volume ratio of 3:1), sonicate for 5 min to obtain solution B;

[0072] The pretreated carbon cloth was ultrasonically treated in solution B for 30 min. Then, the pretreated carbon cloth and solution B were poured into solution A and stirred for 10 min. The mixture of solution A and solution B and the pretreated carbon cloth were transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 130℃ for 12 h. After the reaction was completed, the mixture was taken out, rinsed three times each with ethanol and deionized water, and dried at 60℃ to obtain the Co-TCPP / CC composite material, denoted as Co-TCPP / CC.

[0073] Comparative Example 3

[0074] This comparative example discloses a method for preparing a Co-BTB / GO / CC composite material, including the following steps:

[0075] Step (1): The carbon cloth with a specification of 1.5cm×1cm is ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0076] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After the exfoliation was completed, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material.

[0077] Step (2): Dissolve 10 mg of H3BTB (1,3,5-tris(4-carboxyphenyl)benzene) and 25 mg of Co(NO3)2•6H2O in a mixed solvent of 15 mL DMF (N,N-dimethylformamide) and 0.5 mL acetic acid, and sonicate for 5 min to obtain a mixed solution;

[0078] The GO / CC composite material and the mixed solution were transferred together to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 170°C for 24 hours. After the reaction was completed, the material was removed, rinsed three times each with ethanol and deionized water, and dried at 60°C to obtain the Co-BTB / GO / CC composite material, denoted as Co-BTB / GO / CC.

[0079] Comparative Example 4

[0080] This comparative example discloses a method for preparing GO / CC composite material, including the following steps:

[0081] The carbon cloth with a specification of 1.5cm×1cm was ultrasonically washed in acetone, anhydrous ethanol and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth.

[0082] The washed carbon cloth was connected to an electrochemical workstation as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were immersed in a 0.7 mol / L Na2SO4 aqueous solution. A constant voltage of +2.5 V was applied between the washed carbon cloth and the platinum sheet electrode for electrochemical exfoliation for 10 min. After exfoliation, the carbon cloth was removed, rinsed three times with deionized water, and dried at 60 °C to obtain the GO / CC composite material, denoted as GO / CC.

[0083] Comparative Example 5

[0084] This comparative example discloses a pretreatment method for carbon cloth, including the following steps:

[0085] A 1.5cm × 1cm carbon cloth was ultrasonically washed in acetone, anhydrous ethanol, and deionized water for 30 minutes in sequence, and then dried to obtain the washed carbon cloth, denoted as CC.

[0086] Experimental data characterization and performance testing

[0087] like Figures 1-7 As shown in Table 1, the energy storage performance of the composite materials prepared in Examples 1-4 and Comparative Examples 1-3 were tested respectively.

[0088] The energy storage performance testing process specifically involved using a standard three-electrode system. The composite materials prepared in Examples 1-4 and Comparative Examples 1-3 were used as the working electrode, the Hg / HgO electrode as the reference electrode, and a platinum sheet as the counter electrode. A 1 mol / L KOH aqueous solution was used as the electrolyte for capacitance performance testing. All tests were conducted on a CHI760F electrochemical workstation. Constant current charge-discharge (CP) curves were measured at different current densities, and the specific capacitance and rate performance were calculated.

[0089] Table 1. Specific capacitance of the composite materials prepared in the examples and comparative examples at different current densities.

[0090]

[0091] Figure 1 The three-electrode system constructed from the Co-TCPP / GO / CC-110 composite material prepared in Example 1 is shown to operate at 1 mA / cm². 2 The specific capacitance at current density is 824 mF / cm 2 At 10mA / cm 2 The rate performance at current density is 69.5%; Figure 2 The three-electrode system constructed from the Co-TCPP / GO / CC-120 composite material prepared in Example 2 is shown to operate at 1 mA / cm². 2 The specific capacitance at current density is 2625 mF / cm 2 At 10mA / cm 2 The rate performance at current density is 85.8%; Figure 3 The three-electrode system constructed from the Co-TCPP / GO / CC-130 composite material prepared in Example 3 is shown to operate at 1 mA / cm². 2 The specific capacitance at current density is 2705 mF / cm 2 At 10mA / cm 2 The rate performance at current density is 86%; Figure 4 The three-electrode system constructed from the Co-TCPP / GO / CC-140 composite material prepared in Example 4 is shown to operate at 1 mA / cm². 2 The specific capacitance at the current density is 549.8 mF / cm. 2 At 10mA / cm 2 The rate performance at current density is 60.4%.

[0092] Depend on Figures 1-4As shown in Table 1, by comparing the specific capacitance values ​​of the Co-TCPP / GO / CC materials prepared in Examples 1-4, it was found that the Co-TCPP / GO / CC material prepared in Example 3 had the highest specific capacitance value. Furthermore, the difference in the preparation process between Examples 1-4 lies in the reaction temperature. This indicates that when preparing the Co-TCPP / GO / CC material with optimal performance, if the reaction temperature is too low, the bonding between Co-TCPP and GO / CC (carbon cloth) may rely on van der Waals forces or weak chemical interactions. At low temperatures, it is difficult to form strong chemical bonds, resulting in high resistance to interfacial charge transport and easy material detachment during the reaction. If the reaction temperature is too high, it may lead to partial thermal decomposition of the organic ligands (TCPP) in Co-TCPP or cause excessive aggregation of metal clusters, resulting in a reduction in active sites. In addition, high temperatures may cause excessive growth of MOF crystals, leading to agglomeration, reducing specific surface area and accessibility of active sites, thus affecting the specific capacitance value of the material.

[0093] Figure 5 The three-electrode system constructed from the Co-TCPP@GO / CC composite material prepared in Comparative Example 1 is shown to operate at 1 mA / cm². 2 The specific capacitance at the current density is 1203.1 mF / cm. 2 At 10mA / cm 2 The rate performance at current density is 52%; Figure 6 The three-electrode system constructed from the Co-TCPP / CC composite material prepared in Comparative Example 2 is shown to operate at 1 mA / cm. 2 The specific capacitance at the current density is 225.2 mF / cm. 2 At 10mA / cm 2 The rate performance at current density is 83.7%; Figure 7 The three-electrode system constructed from the Co-BTB / GO / CC composite material prepared in Comparative Example 3 shows that at 1 mA / cm 2 The specific capacitance at the current density is 118.3 mF / cm. 2 At 10mA / cm 2 The rate performance at current density is 81.2%.

[0094] Depend on Figure 5 As shown in Table 1, the Co-TCPP@GO / CC composite material prepared in Comparative Example 1 has good specific capacitance but poor rate performance at current densities of 1, 2, 4, 6, 8 and 10 mA / cm². 2 The specific capacitances at those times were 1203.1, 1086.2, 931.6, 816, 711.1, and 626 mF / cm, respectively. 2 Its specific capacitance starts from a low current density of 1 mA / cm² 2 Increase 10 times to 10 mA / cm 2At that time, the capacitance retention rate was 52%. Although it has a relatively high specific capacitance and capacitance retention rate, it is still at a lower level compared to the composite material prepared in Example 3. This indicates that compared to a simple mixture of two materials, the composite material formed by the interaction of Co-TCPP and GO / CC can produce a stronger synergistic effect, thereby significantly optimizing the energy storage performance of the material.

[0095] Depend on Figure 6 As shown in Table 1, the Co-TCPP / CC composite material prepared in Comparative Example 2 exhibits good rate capability but poor specific capacitance at current densities of 1, 2, 4, 6, 8, and 10 mA / cm². 2 The specific capacitances at the following times were 225.2, 223.6, 211.8, 205.9, 196.4 and 188.6 mF / cm, respectively. 2 Its specific capacitance starts from a low current density of 1 mA / cm² 2 Increase 10 times to 10 mA / cm 2 At that time, the capacitance retention rate was 83.7%. This indicates that GO (graphene oxide), as an intermediate layer, greatly optimized the electronic conduction path and mass transport channel of Co-TCPP, while also producing a synergistic effect with Co-TCPP. In contrast, the surface of the bare CC in Comparative Example 2 is mainly inert carbon material with fewer chemical functional groups. The growth of MOF on it may rely more on physical adsorption, resulting in weak binding force, uneven distribution, and easy detachment from the substrate, leading to the lower specific capacity of Comparative Example 2.

[0096] Depend on Figure 7 As shown in Table 1, the Co-BTB / GO / CC composite material prepared in Comparative Example 3 exhibits good rate capability but poor specific capacitance at current densities of 1, 2, 4, 6, 8, and 10 mA / cm². 2 The specific capacitances at the following times were 118.3, 111.5, 107.7, 106.2, 100, and 96 mF / cm, respectively. 2 Its specific capacitance starts from a low current density of 1 mA / cm² 2 Increase 10 times to 10 mA / cm 2 At that time, the capacitance retention was 81.2%. This indicates that the large conjugated structure of TCPP facilitates efficient electron transport with the GO substrate and optimizes the electronic structure of the active center. Although the BTB ligand used in Comparative Example 3 also has a benzene ring, its degree of conjugation and planarity are far inferior to the porphyrin macrocycle. Its π-π interaction with GO may be weaker, resulting in a lower specific capacity.

[0097] Figure 8The graph shows a comparison of the cyclic voltammetry (CV) curves of the materials prepared in Example 3 of this invention, and Comparative Examples 4 and 5, at a scan rate of 5 mV / s. The graph shows that the curve for the carbon cloth is almost a flat straight line, indicating that the carbon cloth itself does not exhibit significant redox activity. The GO / CC curve shows a weak redox peak, indicating that it has some electrochemical activity, but it is very weak. In contrast, the CV curve of the composite material has the largest and sharpest redox peak, indicating that the introduction of two-dimensional conjugated MOFs greatly enhances the electrochemical activity of the material, suggesting that the oxidation reaction of this material is reversible and rapid.

[0098] Figure 9 These are scanning electron microscope (SEM) images of the materials prepared in Example 3, Comparative Examples 4 and 5 of this invention. Figure 9 As shown, Figure 9 (a) is a scanning electron microscope image of the untreated carbon cloth CC in Comparative Example 5. The carbon fiber has a complete and smooth surface with a small number of structure-related grooves, which is typical of carbon fiber structure. Figure 9 (b) is a scanning electron microscope image of the carbon cloth GO / CC composite material after electrochemical exfoliation in Comparative Example 4. The original small grooves on the carbon fiber surface become less distinct. This is because the exfoliation of carbon fibers initially occurs at the gaps between the graphite layers. After surface exfoliation, the part above the groove will be clearly exfoliated. The exfoliation layer can increase the surface area of ​​the carbon cloth to a certain extent, but the increased surface area is not enough to bring about a major change in the performance of the carbon cloth. Figure 9 (c) Figure 9 (d) is a scanning electron microscope image of the Co-TCPP / GO / CC-130 composite material prepared in Example 3. The image shows that these well-aligned Co-TCPP nanosheets grow uniformly on the GO / CC surface, forming a stable network structure with a large number of open spaces. This unique structure greatly promotes rapid and efficient ion charge transfer and electron transport by providing a shorter mass transfer distance.

[0099] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing MOFs / GO / CC composite materials, characterized in that, Includes the following steps: Step (1): Ultrasonically wash the carbon cloth and dry it to obtain the washed carbon cloth; The washed carbon cloth was electrochemically peeled off using an electrochemical method. After peeling, it was taken out, washed, and dried to obtain the GO / CC composite material. Step (2): Place the GO / CC composite material in a mixed solution of methyl-tetra(4-carboxyphenyl)porphyrin, polyvinylpyrrolidone and Co(NO3)2•6H2O, and react it using a one-step hydrothermal method. After the reaction is completed, remove the material to obtain the MOFs / GO / CC composite material.

2. The method for preparing a MOFs / GO / CC composite material according to claim 1, characterized in that, In step (1), the ultrasonic washing operation includes: ultrasonically washing the carbon cloth with acetone, ethanol and water in sequence.

3. The method for preparing a MOFs / GO / CC composite material according to claim 1, characterized in that, In step (1), the electrochemical stripping operation includes: connecting the washed carbon cloth to the electrochemical workstation as the working electrode, immersing the working electrode, reference electrode, and counter electrode in the electrolyte, applying a constant voltage of +1.5~+2.5 V between the working electrode and the counter electrode, and performing electrochemical stripping for 10~15 min.

4. The method for preparing a MOFs / GO / CC composite material according to claim 3, characterized in that, In the electrochemical stripping operation in step (1), the reference electrode is Ag / AgCl; the counter electrode is a platinum sheet electrode; and the electrolyte is a 0.65~0.75mol / L Na2SO4 aqueous solution.

5. The method for preparing a MOFs / GO / CC composite material according to claim 1, characterized in that, In step (2), the solid-liquid ratio of the GO / CC composite material to the mixed solution of 1g:150mL~160mL is 1g:150mL~160mL. The mixed solution of 1g:150mL~160mL is prepared by mixing the mixed solution of 1g:150mL~160mL with the Co(NO3)2•6H2O solution.

6. The method for preparing a MOFs / GO / CC composite material according to claim 5, characterized in that, In step (2): The mixture of methyl-tetra(4-carboxyphenyl)porphyrin is prepared by the following steps: dissolving 8-10 mg of methyl-tetra(4-carboxyphenyl)porphyrin and 15-20 mg of polyvinylpyrrolidone in 10-12 mL of mixed solvent and stirring until homogeneous; The Co(NO3)2•6H2O solution is prepared by the following steps: dissolving 0.0180~0.0185g of Co(NO3)2•6H2O in 4~6mL of mixed solvent and sonicating for 5~10min; The above-mentioned mixed solvents were all prepared by mixing N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to 3:1.

3.

7. The method for preparing a MOFs / GO / CC composite material according to claim 6, wherein step (2), the one-step hydrothermal method includes: The mixture of 1,4-tetra(4-carboxyphenyl)porphyrin was used as solution A, and the Co(NO3)2•6H2O solution was used as solution B. The GO / CC composite material was placed in solution B and ultrasonically treated for 20-30 min. Then, the GO / CC composite material and solution B were poured into solution A and stirred for 10-15 min to react.

8. The method for preparing a MOFs / GO / CC composite material according to claim 7, wherein in step (2), the reaction conditions are: reacting at 110~140℃ for 10~12h.

9. A MOFs / GO / CC composite material prepared by the method for preparing MOFs / GO / CC composite materials as described in any one of claims 1 to 8.

10. An application of the MOFs / GO / CC composite material as described in claim 9 in the field of electrochemical energy storage.

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