Carbon nanotube macroassembly / MOF flexible composite material, preparation method therefor and use thereof

Abstract

The present application relates to the technical field of chemical manufacturing and carbon materials and provides a carbon nanotube macroassembly / MOF flexible composite material, a preparation method therefor, and a use thereof. The flexible composite material is formed by combining a carbon nanotube macroassembly and MOF. The MOF is bound on the surface of the carbon nanotube macroassembly in a chemical bond crosslinking manner; and the carbon nanotube macroassembly is a carbon nanotube film with a free-standing structure, or a carbon nanotube fiber formed by cutting and twisting a carbon nanotube film with a free-standing structure. In the present application, after a surface functionalization treatment is carried out on the carbon nanotube macroassembly, an MOF porous material layer is stably and uniformly loaded on the surface of the carbon nanotube macroassembly with a high curvature in a solution impregnation manner. The morphology and density of the porous material grown on the surface of the carbon nanotube macroassembly are regulated by regulating the degree of surface functionalization, so that a flexible composite material with excellent structural stability and conductivity is obtained.

Description

A carbon nanotube macrobody / MOF flexible composite material, preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on February 28, 2024, with application number 202410222734.8 and entitled “A Carbon Nanotube Macrobody / MOF Flexible Composite Material, Preparation Method and Application Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the fields of chemical manufacturing and carbon material technology, and in particular to a carbon nanotube macrobody / MOF flexible composite material, a preparation method and applications thereof. Background Art

[0004] Metal-organic framework (MOF) materials are a new type of porous material with different framework structures constructed by the mutual linkage of metal cations and organic ligands. They have the excellent characteristics of large specific surface area, large porosity, and adjustable structure and chemical properties. They show important application potential in the fields of adsorption separation, storage, energy conversion and industrial catalysis.

[0005] Despite this, the current promotion and application of MOF materials still faces significant challenges in material formation. Powdered MOFs are difficult to assemble into stable macrostructures, limiting their practical applications. A typical assembly technique involves loading MOF materials onto a substrate to form a two-dimensional MOF membrane. For this assembly method, selecting the appropriate substrate and deposition method are crucial for the composite's ultimate performance and practical application. Currently, non-flexible inorganic or organic materials, such as copper mesh, iron mesh, and polytetrafluoroethylene, are commonly used as substrates.

[0006] However, non-flexible membranes are prone to stress concentration, which can cause the MOF layer to break and fall off.

[0007] Overview

[0008] In response to the above-mentioned problems existing in the prior art, the present application provides a simple, widely applicable and efficient carbon nanotube macrobody / MOF flexible composite material, a preparation method and its application. By using chemical bond cross-linking, a dense MOF layer is loaded on the surface of a flexible carbon nanotube macrobody, thereby obtaining a carbon nanotube macrobody / MOF flexible composite material with stable and adjustable structure and morphology.

[0009] The specific content of the invention is as follows:

[0010] In a first aspect, the present application provides a carbon nanotube macrobody / MOF flexible composite material, wherein the carbon nanotube macrobody / MOF flexible composite material is composed of a carbon nanotube macrobody and a MOF, wherein the MOF is bonded to the surface of the carbon nanotube macrobody in the form of chemical cross-linking;

[0011] The carbon nanotube macrobody is a carbon nanotube film or carbon nanotube fiber with a self-supporting structure;

[0012] The carbon nanotube fiber is formed by twisting the strip-shaped carbon nanotube film.

[0013] Optionally, the carbon nanotube film is prepared by a floating catalytic chemical vapor deposition method, and the thickness of the carbon nanotube film is 1-30 μm;

[0014] The diameter of the carbon nanotube fiber is 20-200 μm.

[0015] Optionally, the MOF is HKUST-1, ZIF-8, ZIF-67, UIO-66 or MIL-100(Fe).

[0016] In a second aspect, the present application provides a method for preparing the carbon nanotube macrobody / MOF flexible composite material described in the first aspect, the preparation method comprising:

[0017] Step 1: Immersing the carbon nanotube macrobody in an inorganic base solution to pre-deposit the inorganic base on the surface of the carbon nanotube macrobody; or immersing the carbon nanotube macrobody in a strong oxidizing acid solution to carboxylate the surface of the carbon nanotube macrobody to obtain a surface functionalized carbon nanotube macrobody;

[0018] Step 2: Immersing the surface functionalized carbon nanotube macrobody in a metal cation solution, wherein the metal ions are bonded to the surface of the surface functionalized carbon nanotube macrobody in the form of chemical cross-linking to form a composite material precursor;

[0019] Step 3: further immersing the composite material precursor in an organic ligand solution for 10 to 90 minutes, wherein the organic ligand combines with the metal ions to form MOF, thereby preparing the carbon nanotube macrobody / MOF composite material.

[0020] Optionally, in step 1, the inorganic alkaline solution is one or more of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate or ammonium bicarbonate;

[0021] The concentration of the inorganic alkali solution is 1 to 3 mol / L;

[0022] The carbon nanotube macro-body is immersed in the inorganic alkaline solution for 10-60 minutes.

[0023] Optionally, in step 1, the strong oxidizing acid is a mixed acid solution or a 30% hydrogen peroxide solution, wherein the mixed acid solution is formed by mixing concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1; or the mixed acid solution is formed by mixing potassium permanganate and concentrated sulfuric acid, and the content of potassium permanganate is 0.5-1.5 g / L;

[0024] The carbon nanotube macro-body is immersed in the strong oxidizing acid solution for 0.5-4 hours.

[0025] Optionally, the carbon nanotube fibers are obtained by the following method:

[0026] Spreading and compacting the carbon nanotube film, and cutting out uniform strip-shaped carbon nanotube film with a blade;

[0027] The strip-shaped carbon nanotube film is twisted by a twisting machine to obtain carbon nanotube fibers with a diameter of 20-200 μm.

[0028] Optionally, in step 2, the concentration of the metal cation solution is 0.1-1 mol / L;

[0029] The solvent of the metal cation solution is one or more of water, ethanol, methanol, ethylene glycol and DMF;

[0030] The metal cation of the metal cation solution is Cu 2+ 、Zn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zr 4+ One or more of;

[0031] The surface functionalized carbon nanotube macro-body is immersed in the metal cation solution for 12 to 24 hours.

[0032] Optionally, in step 3, the concentration of the organic ligand solution is 0.01 to 0.1 mol / L;

[0033] The solvent of the organic ligand solution is formed by mixing water and an organic solvent in a volume ratio of 5-25:75-95, and the organic solvent is one or more of ethanol, methanol, ethylene glycol and DMF;

[0034] The organic ligand of the organic ligand solution is one or more of trimesic acid, terephthalic acid, biphenyl dicarboxylic acid and dimethylimidazole;

[0035] The flexible composite material precursor is immersed in the organic ligand solution for 10 to 90 minutes.

[0036] In a third aspect, the present application provides an application of the carbon nanotube macrobody / MOF flexible composite material described in the first aspect above, wherein the carbon nanotube macrobody / MOF flexible composite material is used for gas sensing and flexible electrode materials.

[0037] Compared with the prior art, this application has the following advantages:

[0038] The present application provides a flexible composite material composed of a carbon nanotube macrobody and MOF. The MOF is bonded to the surface of the carbon nanotube macrobody in the form of chemical crosslinking; the carbon nanotube macrobody is a carbon nanotube film with a self-supporting structure, or a carbon nanotube fiber cut from a carbon nanotube film with a self-supporting structure. The present application achieves a stable and uniform loading of a MOF porous material layer on the surface of a carbon nanotube macrobody with a high curvature by solution impregnation after surface functionalization of the carbon nanotube macrobody. The morphology and density of the porous material grown on the surface of the carbon nanotube macrobody are regulated by regulating the degree of surface functionalization, thereby obtaining a flexible composite material with excellent structural stability and conductive properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following is a brief introduction to the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] FIG1 shows a flow chart of a method for preparing a carbon nanotube macrobody / MOF flexible composite material provided in an embodiment of the present application;

[0041] FIG2 shows a scanning electron microscope image of a carbon nanotube film / HKUST-1 flexible composite material provided in an embodiment of the present application;

[0042] FIG3 shows a scanning electron microscope image of another carbon nanotube film / HKUST-1 flexible composite material provided in an embodiment of the present application;

[0043] FIG4 shows a scanning electron microscope image of a carbon nanotube film / ZIF-8 flexible composite material provided in an embodiment of the present application;

[0044] FIG5 shows a scanning electron microscope image of another carbon nanotube film / ZIF-8 flexible composite material provided in an embodiment of the present application;

[0045] FIG6 shows a scanning electron microscope image of a carbon nanotube fiber / HKUST-1 flexible composite material provided in an embodiment of the present application;

[0046] FIG7 shows a scanning electron microscope image of a carbon nanotube film / ZIF-8 flexible composite material provided in a comparative example of the present application;

[0047] FIG8 shows a scanning electron microscope image of another carbon nanotube film / ZIF-8 flexible composite material provided in a comparative example of the present application. Specific embodiments

[0048] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0049] If no specific experimental steps or conditions are specified in the examples, the experiments can be carried out according to the conventional experimental steps or conditions described in the prior art. The reagents and other instruments used, if the manufacturers are not specified, are all commercially available conventional reagents.

[0050] Carbon nanotubes (CNTs) are a new class of carbon materials. Due to their unique structure and exceptional performance, they are expected to become a key material in cutting-edge fields such as aerospace, military equipment, and communications sensing. For practical applications, the preparation of multidimensional CNT macrostructures is a prerequisite for realizing their potential. Common examples include CNT films and fibers. These macrostructures, assembled from a large number of individual CNTs with excellent mechanical and electrical properties, also exhibit exceptional mechanical and electrical properties at the macroscale, forming a self-supporting, cross-linked network capable of effectively transferring loads and transporting electrons.

[0051] Based on this, the embodiment of the present application uses flexible self-supporting carbon nanotube macro-bodies as carriers for the growth and assembly of MOF porous materials. The self-supporting flexible carbon nanotube macro-body network structure constructed with a large number of carbon nanotubes with large length, high aspect ratio and large specific surface area can provide a large number of nucleation sites for the assembly of MOF materials, and the network structure composed of long carbon nanotubes has both flexibility and high strength, which can effectively ensure the stability of the self-supporting structure. Moreover, since the self-supporting network structure can provide a large number of dispersed nucleation sites, it effectively reduces the aggregation of MOF porous materials on the surface of the substrate, which is conducive to maintaining the stability of the structure and morphology of the composite material. At the same time, the assembly process of the self-supporting substrate and MOF porous material involves the formation of a more complex multi-level structure. The rich multi-level structure design and assembly are conducive to the effective realization of rich structure-function regulation. The specific implementation content is as follows:

[0052] In a first aspect, the present application provides a carbon nanotube macrobody / MOF flexible composite material composed of a carbon nanotube macrobody and a MOF, wherein the MOF is chemically cross-linked to the surface of the carbon nanotube macrobody, thereby achieving a stable and uniform loading of a porous material layer (MOF) on the surface of the carbon nanotube macrobody having a certain curvature.

[0053] In a specific implementation, the carbon nanotube macrostructure is a self-supporting carbon nanotube film. The self-supporting carbon nanotube film can be prepared by floating catalytic chemical vapor deposition. The specific preparation method can be referenced in CN 113279090 B and CN 109436916 A. Other preparation methods are also possible and are not limited in this application. The thickness of the carbon nanotube film ranges from 1 to 30 μm.

[0054] Alternatively, the carbon nanotube macrobody can also be a carbon nanotube membrane with a self-supporting structure cut into strips, and then twisted to form carbon nanotube fibers with a certain diameter. The specific processing process includes: flattening and compacting the carbon nanotube membrane, and cutting out a uniform strip of carbon nanotube membrane with a blade; twisting the strip of carbon nanotube membrane through a twisting machine to obtain carbon nanotube fibers with a diameter of 20-200μm.

[0055] In a specific implementation, MOF is selected from HKUST-1, ZIF-8, ZIF-67, UIO-66 or MIL-100(Fe).

[0056] In a second aspect, the present application provides a method for preparing the carbon nanotube macrobody / MOF flexible composite material described in the first aspect above. FIG1 shows a flow chart of the method for preparing the carbon nanotube macrobody / MOF flexible composite material provided in an embodiment of the present application. As shown in FIG1 , the preparation method comprises:

[0057] S1. Immersing the carbon nanotube macrobody in an inorganic base solution to pre-deposit an inorganic base on the surface of the carbon nanotube macrobody; or immersing the carbon nanotube macrobody in a strong oxidizing acid solution to carboxylate the surface of the carbon nanotube macrobody to obtain a surface-functionalized carbon nanotube macrobody;

[0058] S2, immersing the surface functionalized carbon nanotube macrobody in a metal cation solution, wherein the metal ions are bonded to the surface of the surface functionalized carbon nanotube macrobody in the form of chemical cross-linking to form a composite material precursor;

[0059] S3. The composite material precursor is further immersed in an organic ligand solution for 10 to 90 minutes, wherein the organic ligand combines with the metal ions to form MOF, thereby preparing a carbon nanotube macrobody / MOF composite material.

[0060] In specific implementation, the carbon nanotube film is prepared using a floating catalyst chemical vapor deposition reaction system in a safe atmosphere, which specifically includes the following steps:

[0061] Ferrocene and sulfur powder in a mass ratio of 5 to 30 are ground and evenly mixed to obtain a solid catalyst. 10 to 30 mg of the solid catalyst is placed in a small quartz boat and placed in the inlet area of ​​the quartz tube. The outer wall of this area is wrapped with a heating tape for heating and sublimating the catalyst, which is carried into the reaction tube by the carrier gas to react.

[0062] Raise the temperature of the constant temperature zone of the reaction tube to a reaction temperature of 1050-1150°C at a rate of less than 30°C / min. Simultaneously, introduce 100 sccm of argon to expel air from the reaction tube. Once the reaction zone reaches the reaction temperature, maintain the constant temperature for 15-30 minutes. Simultaneously, turn on the heating zone and set the temperature to 80-120°C to allow the catalyst to slowly sublime and be carried into the reaction tube by the carrier gas.

[0063] After maintaining a constant temperature for 15 to 30 minutes, 5 to 10 sccm of methane carbon source is introduced. A large number of carbon nanotubes begin to react in the reaction tube and agglomerate into a cylindrical carbon nanotube aerogel structure. At the same time, the argon carrier gas flow rate is adjusted to 1000 to 2000 sccm to carry the carbon nanotube aerogel product out of the reaction tube.

[0064] The roller driven by the stepper motor winds up the carbon nanotube aerogel discharged from the reaction tube layer by layer to obtain a uniform carbon nanotube film; the roller material can be one of quartz, polytetrafluoroethylene, and polyvinylidene fluoride. The collection time is 5 to 40 minutes, and the thickness of the carbon nanotube film can be adjusted by the collection time.

[0065] The roller wrapped with the carbon nanotube film is removed and placed in acetone for densification treatment, and then the carbon nanotube film on the roller is directly peeled off with tweezers to obtain a self-supporting carbon nanotube film structure.

[0066] In specific implementation, the carbon nanotube fibers are assembled using the carbon nanotube film prepared in a safe atmosphere as the material basis. The assembly process includes:

[0067] The densified carbon nanotube film was spread flat and compacted with a polytetrafluoroethylene plate, and then cut out with a blade to obtain a uniform strip-like structure.

[0068] One end of the cut carbon nanotube strip is clamped with a small twisting machine clamp and the other end is clamped with tweezers. The carbon nanotube fiber is twisted by the twisting machine. The diameter of the carbon nanotube fiber can be controlled by controlling the width and thickness of the strip. The diameter range is 20-200μm. The smaller the diameter, the greater the curvature of the carbon nanotube fiber.

[0069] The embodiments of the present application perform surface functionalization on carbon nanotube macrobodies to render their surfaces reactive. Combined with the method of growing MOF through immersion, this method allows for the growth of a relatively stable and uniform porous material layer (MOF) on the surface of a carbon nanotube macrobodies with high curvature. Compared to existing composite powder materials prepared by ultrasonically mixing a carbon nanotube dispersion with a MOF precursor solution, the morphology of the materials differs significantly, and the structure and overall stability are inferior to those of the present application. Compared to composite powder materials prepared by connecting carbon nanotubes and MOFs via van der Waals forces, relying solely on weak van der Waals forces makes it difficult to form a stable interface connection, resulting in poor stability.

[0070] In specific implementation, the surface functionalization adopts pre-deposition of inorganic base or surface carboxylation treatment. The inorganic base solution involved in the pre-deposition of inorganic base is one or more of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate or ammonium bicarbonate, with a concentration between 1 and 3 mol / L. The immersion time of the carbon nanotube macrobody in the inorganic base solution is controlled to be 10-60 min; the strong oxidizing acid involved in the surface carboxylation treatment is a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of potassium permanganate and concentrated sulfuric acid or a hydrogen peroxide solution, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid formed by concentrated sulfuric acid and concentrated nitric acid is 3:1, and the content of potassium permanganate in the mixed acid formed by potassium permanganate and concentrated sulfuric acid is 0.5-1.5 g / L; the immersion time of the carbon nanotube macrobody in the strong oxidizing acid solution is 0.5-4 h.

[0071] This application uses an impregnation method to achieve in-situ assembly of MOF on the surface of a carbon nanotube macrobody, resulting in a flexible composite material. Specifically, the carbon nanotube macrobody is sequentially immersed in a metal cation solution and then an organic ligand solution. The metal cations chemically crosslink and bond with the surface-functionalized carbon nanotube macrobody. The organic ligands further bind to the metal cations, thereby growing a relatively stable and uniform MOF porous material layer on the surface of the highly curvatured carbon nanotube macrobody.

[0072] In specific implementation, the concentration of the metal cation solution involved in the impregnation process is 0.1-1 mol / L; the solvent of the metal cation solution is one or more of water, ethanol, methanol, ethylene glycol and DMF; the metal cation of the metal cation solution is Cu 2+ 、Zn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zr 4+one or more of the following: the immersion time of the surface functionalized carbon nanotube macrobody in the metal cation solution is 12 to 24 hours; the concentration of the organic ligand solution is 0.01 to 0.1 mol / L; the solvent of the organic ligand solution is formed by mixing water and an organic solvent in a volume ratio of 5-25:75-95, and the organic solvent is one or more of ethanol, methanol, ethylene glycol and DMF; the organic ligand of the organic ligand solution is one or more of trimesic acid, terephthalic acid, diphenyl dicarboxylic acid and dimethylimidazole; the immersion time of the flexible composite material precursor in the organic ligand solution is 10 to 90 minutes.

[0073] In a third aspect, the present application provides an application of the carbon nanotube macrobody / MOF flexible composite material according to the first aspect, wherein the carbon nanotube macrobody / MOF flexible composite material is used for gas sensing and flexible electrode materials.

[0074] In order to enable those skilled in the art to understand the present application more clearly, the carbon nanotube macrobody / MOF flexible composite material, preparation method and application thereof described in the present application are now described in detail through the following examples.

[0075] Example 1: Preparation of carbon nanotube film / HKUST-1 flexible composite material

[0076] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0077] A three-temperature-zone horizontal tube furnace with a constant temperature section greater than 40 cm was used as a reactor to carry out a gas-solid reaction under normal pressure. A polytetrafluoroethylene roller was placed at the outlet to receive the produced carbon nanotube film. A mixture of ferrocene / sulfur (mass ratio 20) was selected as a catalyst, which was fully ground and mixed. 10 mg was weighed into a small quartz boat and placed at the inlet of the reaction tube in contact with the air. The quartz tube was wrapped with a heating tape and heated to 80°C during the reaction stage to allow the catalyst to sublime and be entrained into the reaction system by the gas. The reactor was heated to a target reaction temperature of 1100°C at a heating rate of 30°C / min, while a flow rate of 100 sccm was used. Argon is used as a carrier gas to exhaust the air in the reactor; during the reaction stage, the system temperature is maintained at 1100°C, and the carrier gas is replaced with 1000sccm of argon, the reaction carbon source is 5sccm of methane, and 3sccm of hydrogen is passed as an etchant to improve the quality of carbon nanotubes; when the reaction is stable, the cylindrical carbon nanotube aerogel produced by the reaction is stably ejected from the outlet of the reaction tube under the blowing of argon carrier gas, and contacts a polytetrafluoroethylene roller driven by a stepper motor for winding and collection, and the collection time is 30 minutes; after the reaction is completed, the roller is removed and immersed in acetone to densify, and the carbon nanotube film on the roller is directly peeled off with tweezers to obtain a self-supporting carbon nanotube film structure.

[0078] (2) Assembly of carbon nanotube film and HKUST-1

[0079] The carbon nanotube film prepared by chemical vapor deposition was immersed in a 1 mol / L K2CO3 solution. After soaking at room temperature for 30 minutes, the carbon nanotube film was taken out from the K2CO3 solution and heated to dry in air. The treated carbon nanotube film was then immersed in a 0.5 mol / L Cu(NO3)2 ethanol solution. After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in sequence, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L tricarboxylic acid solution, the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, the film was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0080] FIG2 shows a scanning electron microscope image of the carbon nanotube film / HKUST-1 flexible composite material provided in an embodiment of the present application. As shown in FIG2 , a dense layer of HKUST-1 can be grown on the surface of the carbon nanotube film with good crystal phase and uniformity.

[0081] Example 2: Preparation of carbon nanotube film / HKUST-1 flexible composite material

[0082] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0083] The preparation steps are the same as those in Example 1.

[0084] (2) Assembly of carbon nanotube film and HKUST-1

[0085] The carbon nanotube film prepared by chemical vapor deposition was immersed in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, with the volume ratio of the two acids being 3:1. The film was immersed at 80°C for 4 hours, and then washed thoroughly with deionized water to remove the residual mixed acid on the surface, and then heated and dried in air. The treated carbon nanotube film was then immersed in a 0.5 mol / L Cu(NO3)2 ethanol solution. After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in turn, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L tricarboxylic acid solution, with the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, the film was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0086] FIG3 shows a scanning electron microscope image of the carbon nanotube film / HKUST-1 flexible composite material provided in an embodiment of the present application. As shown in FIG3 , in this embodiment, HKUST-1 can be grown on the surface of the carbon nanotube film, but the density and uniformity are lower than those of the preparation method provided in Example 2.

[0087] Example 3: Preparation of carbon nanotube film / ZIF-8 flexible composite material

[0088] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0089] The preparation steps are the same as those in Example 1.

[0090] (2) Assembly of carbon nanotube film / ZIF-8

[0091] The carbon nanotube film prepared by chemical vapor deposition was immersed in a 1 mol / L K2CO3 solution. After soaking at room temperature for 60 minutes, the carbon nanotube film was taken out from the K2CO3 solution and heated to dry in air. The treated carbon nanotube film was then immersed in a 0.05 mol / L zinc acetate solution, the solvent being a mixed solution of deionized water and ethanol (3:7). After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in sequence, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L dimethylimidazole solution, the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, it was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0092] Figure 4 shows a scanning electron microscope image of the carbon nanotube film / ZIF-8 flexible composite material provided in an embodiment of the present application. As shown in Figure 4, a relatively dense layer of ZIF-8 can be grown on the surface of the carbon nanotube film in this embodiment, and has good crystal phase and uniformity.

[0093] Example 4: Preparation of carbon nanotube film / ZIF-8 flexible composite material

[0094] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0095] The preparation steps are the same as those in Example 1.

[0096] (2) Assembly of carbon nanotube film / ZIF-8

[0097] The carbon nanotube film prepared by chemical vapor deposition was immersed in a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, with the volume ratio of the two acids being 3:1. The film was immersed at 80°C for 2 hours, and then washed thoroughly with deionized water to remove the residual mixed acid on the surface, and then heated to dry in air. The treated carbon nanotube film was then immersed in a 0.05 mol / L zinc acetate solution, with the solvent being a mixed solution of deionized water and ethanol (3:7). After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in sequence, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L dimethylimidazole solution, with the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, the film was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0098] Figure 5 shows a scanning electron microscope image of the carbon nanotube film / ZIF-8 flexible composite material provided in an embodiment of the present application. As shown in Figure 5, ZIF-8 grains with a good crystalline phase can also grow on the surface of the carbon nanotube film in this embodiment, but the uniformity is reduced and a densely packed structure is presented.

[0099] Example 5: Preparation of carbon nanotube fiber / HKUST-1 flexible composite material

[0100] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0101] The preparation steps are the same as those in Example 1.

[0102] (2) Assembly of carbon nanotube fibers

[0103] A carbon nanotube film prepared by chemical vapor deposition was laid flat and compacted with a polytetrafluoroethylene sheet. A blade was used to cut the resulting uniform ribbons. One end of the cut ribbons was clamped with a small twisting machine fixture and the other end with tweezers. Three different diameters of carbon nanotube fibers (40 μm, 100 μm, and 160 μm) were twisted using the twisting machine.

[0104] (3) Assembly of carbon nanotube fibers and HKUST-1

[0105] Carbon nanotube fibers of three different diameters (40 μm, 100 μm, and 160 μm) were immersed in a 1 mol / L K2CO3 solution at room temperature for 30 minutes. The carbon nanotube fibers were then removed from the K2CO3 solution and heated to dry in air. The treated carbon nanotube fibers were then immersed in a 0.5 mol / L Cu(NO3)2 ethanol solution. After 24 hours, the carbon nanotube fibers were removed and washed with ethanol and deionized water, respectively, and dried at room temperature. The dried carbon nanotube fibers were then immersed in a 0.1 mol / L tricarboxylic acid solution (a mixture of deionized water and ethanol (1:9)) for 1 hour. After immersion, the fibers were removed, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The samples were then stored in a vacuum environment. Table 1 shows the average particle size of the HKUST-1 porous material supported on the surface of carbon nanotube fibers with different diameters.

[0106] Table 1 Average particle size of porous materials on the surface of carbon nanotube fibers with different diameters

[0107] Figure 6 shows a scanning electron microscope image of the carbon nanotube fiber / HKUST-1 flexible composite material provided in an embodiment of the present application. As shown in Figure 6 and Table 1, in this embodiment, a dense layer of HKUST-1 can be grown on the surface of the carbon nanotube fiber with good crystal phase and uniformity, and the particle size of the surface porous material is affected by the curvature of the fiber substrate surface.

[0108] Comparative Example 1: Preparation of carbon nanotube film / HKUST-1 flexible composite material without surface functionalization treatment

[0109] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0110] The preparation steps are the same as those in Example 1.

[0111] (2) Assembly of carbon nanotube film without surface functionalization treatment and HKUST-1

[0112] The carbon nanotube film prepared by chemical vapor deposition was immersed in a 0.5 mol / L Cu(NO3)2 ethanol solution. After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in turn, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L tricarboxylic acid solution, the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, it was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0113] FIG7 shows a scanning electron microscope image of the carbon nanotube film / ZIF-8 flexible composite material provided in the comparative example of the present application. As shown in FIG7 , the carbon nanotube film can also grow MOF with good crystallinity, but the particle size and distribution density are reduced.

[0114] Comparative Example 2: Preparation of carbon nanotube film / ZIF-8 flexible composite material without surface functionalization treatment

[0115] (1) Preparation of carbon nanotube film by floating catalyst chemical vapor deposition

[0116] The preparation steps are the same as those in Example 1.

[0117] (2) Assembly of carbon nanotube film without surface functionalization and ZIF-8

[0118] The carbon nanotube film prepared by chemical vapor deposition was immersed in a 0.05 mol / L zinc acetate solution, the solvent being a mixed solution of deionized water and ethanol (3:7). After 24 hours, the carbon nanotube film was taken out and washed with ethanol and deionized water in sequence, and dried at room temperature. The dried carbon nanotube film was then immersed in a 0.1 mol / L dimethylimidazole solution, the solvent being a mixed solution of deionized water and ethanol (1:9). After soaking for 1 hour, it was taken out, washed thoroughly with ethanol, and dried in a vacuum oven at 100°C for 24 hours. The sample was stored in a vacuum environment.

[0119] Figure 8 shows a scanning electron microscope image of the carbon nanotube film / ZIF-8 flexible composite material provided in the comparative example of the present application. As shown in Figure 8, agglomerates of some grains were observed on the surface of the carbon nanotube film in this comparative example, and no grains with obvious ZIF-8 morphology were observed.

[0120] References herein to "one embodiment," "an embodiment," or "one or more embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Furthermore, please note that instances of the phrase "in one embodiment" do not necessarily all refer to the same embodiment.

[0121] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0122] In the claims, any reference signs placed between brackets shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application may be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A carbon nanotube macrobody / MOF flexible composite material, characterized in that: The carbon nanotube macrobody / MOF flexible composite material is composed of a carbon nanotube macrobody and MOF, and the MOF is bonded to the surface of the carbon nanotube macrobody in the form of chemical cross-linking; The carbon nanotube macrobody is a carbon nanotube film or carbon nanotube fiber with a self-supporting structure; The carbon nanotube fiber is formed by twisting the strip-shaped carbon nanotube film.

2. The carbon nanotube macrobody / MOF flexible composite material according to claim 1, characterized in that: The carbon nanotube film is prepared by a floating catalytic chemical vapor deposition method, and the thickness of the carbon nanotube film is 1-30 μm; The diameter of the carbon nanotube fiber is 20-200 μm.

3. The carbon nanotube macrobody / MOF composite material according to claim 1, characterized in that: The MOF is HKUST-1, ZIF-8, ZIF-67, UIO-66 or MIL-100(Fe).

4. A method for preparing the carbon nanotube macrobody / MOF flexible composite material according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Step 1: Immersing the carbon nanotube macrobody in an inorganic base solution to pre-deposit the inorganic base on the surface of the carbon nanotube macrobody; or immersing the carbon nanotube macrobody in a strong oxidizing acid solution to carboxylate the surface of the carbon nanotube macrobody to obtain a surface functionalized carbon nanotube macrobody; Step 2: Immersing the surface functionalized carbon nanotube macrobody in a metal cation solution, wherein the metal ions are bonded to the surface of the surface functionalized carbon nanotube macrobody in the form of chemical cross-linking to form a composite material precursor; Step 3: further immersing the composite material precursor in an organic ligand solution for 10 to 90 minutes, wherein the organic ligand combines with the metal ions to form MOF, thereby preparing the carbon nanotube macrobody / MOF flexible composite material.

5. The preparation method according to claim 4, characterized in that In step 1, the inorganic alkaline solution is one or more of potassium carbonate, sodium carbonate, ammonium carbonate, potassium bicarbonate or ammonium bicarbonate; The concentration of the inorganic alkali solution is 1 to 3 mol / L; The carbon nanotube macro-body is immersed in the inorganic alkaline solution for 10-60 minutes.

6. The preparation method according to claim 4, characterized in that In step 1, the strong oxidizing acid is a mixed acid solution or a 30% hydrogen peroxide solution, wherein the mixed acid solution is formed by mixing concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1; or the mixed acid solution is formed by mixing potassium permanganate and concentrated sulfuric acid, and the content of potassium permanganate is 0.5-1.5 g / L; The carbon nanotube macro-body is immersed in the strong oxidizing acid solution for 0.5-4 hours.

7. The preparation method according to claim 4, characterized in that In step 1, the carbon nanotube fibers are obtained by the following method: Spreading and compacting the carbon nanotube film, and cutting out uniform strip-shaped carbon nanotube film with a blade; The strip-shaped carbon nanotube film is twisted by a twisting machine to obtain carbon nanotube fibers with a diameter of 20-200 μm.

8. The preparation method according to claim 4, characterized in that In step 2, the concentration of the metal cation solution is 0.1-1 mol / L; The solvent of the metal cation solution is one or more of water, ethanol, methanol, ethylene glycol and DMF; The metal cation of the metal cation solution is Cu 2+ 、Zn 2+ 、Fe 2+ 、Co 2+ 、Ni 2+ and Zr 4+ One or more of; The surface functionalized carbon nanotube macro-body is immersed in the metal cation solution for 12 to 24 hours.

9. The preparation method according to claim 4, characterized in that In step 3, the concentration of the organic ligand solution is 0.01 to 0.1 mol / L; The solvent of the organic ligand solution is formed by mixing water and an organic solvent in a volume ratio of 5-25:75-95, and the organic solvent is one or more of ethanol, methanol, ethylene glycol and DMF; The organic ligand of the organic ligand solution is one or more of trimesic acid, terephthalic acid, biphenyl dicarboxylic acid and dimethylimidazole; The flexible composite material precursor is immersed in the organic ligand solution for 10 to 90 minutes.

10. An application of the carbon nanotube macrobody / MOF flexible composite material according to any one of claims 1 to 3, characterized in that: The carbon nanotube macrobody / MOF flexible composite material is used for gas sensing and flexible electrode materials.

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