Confined channel membrane catalytic material as well as preparation method and application thereof

Abstract

The invention provides a confinement channel membrane catalytic material as well as a preparation method and application thereof, and belongs to the technical field of membrane catalytic materials. The confinement channel membrane catalytic material comprises two oppositely arranged porous substrate layers and a catalytic layer arranged between the two porous substrate layers, wherein the catalyst layer comprises a ZIF-8-based porous carbon material and a monatomic catalyst; the ZIF-8-based porous carbon materials are arranged between the two porous substrate layers in parallel, two adjacent ZIF-8-based porous carbon materials form a confinement channel in the direction perpendicular to the porous substrate layers, and the monatomic catalyst is loaded on the inner surface of the confinement channel.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane catalytic materials, and in particular relates to a confined channel membrane catalytic material and a preparation method and application thereof. Background Art

[0002] In the field of catalytic reactions, advanced membrane technologies enable the rapid separation of reaction solutions and catalysts, while confined channels constructed from membrane materials can confine catalytic reactions to nanoscale spaces. This nanoscale confinement effectively lowers reaction energy barriers and significantly improves catalytic efficiency, demonstrating enormous potential for applications in chemical synthesis, environmental pollutant treatment, and other fields.

[0003] Currently, there are two main types of membrane-based confined channels that have been publicly reported: one is the use of two-dimensional porous nanosheets, or nanopore channels formed by artificial drilling in atomically thin two-dimensional nanosheets; the other is the two-dimensional laminar membrane confined channel formed by stacking and assembling two-dimensional nanosheets. Among them, the two-dimensional laminar membrane confined channel technology has made considerable progress. By combining the nanoconfinement effect with flow chemistry, efficient confined flow reactions based on two-dimensional laminar membrane systems have been achieved, providing innovative ideas for constructing high-conversion flow catalytic systems under mild conditions. Other studies have used two-dimensional nanosheets to construct nanochannels between membrane layers, simultaneously confining nanocatalysts, reactive oxygen species (ROS), and fluids in the interlayers, successfully achieving the rapid degradation of organic pollutants.

[0004] However, the two types of membrane-based confined channels mentioned above still face significant technical bottlenecks. For nanopore channels, on the one hand, they are limited by the high drilling cost and complex processing technology, making it difficult to achieve large-scale preparation; on the other hand, the catalytic active sites within the pores are difficult to precisely control, which affects the optimization of catalytic performance. In the case of two-dimensional laminar membrane confined channels, since the channel direction is perpendicular to the liquid flow direction, the resistance of the liquid passing through the transverse channel between the membranes increases significantly, the liquid flow rate is slow, and thus the membrane flux is low (the maximum flux currently reported does not exceed 150 L·m -2 ·h -1 ), the reaction rate is limited and it is difficult to meet the needs of industrial applications.

[0005] Therefore, how to design a membrane catalytic material that can achieve high-throughput transmission and precisely customize active sites remains a major problem that needs to be overcome in the current catalysis field. Summary of the Invention

[0006] In response to the above technical problems, the present invention provides a confined channel membrane catalytic material and a preparation method and application thereof, in order to at least partially solve the above technical problems. The specific technical solutions provided by the present invention are as follows.

[0007] As a first aspect of the present invention, a confined channel membrane catalytic material is provided, comprising: two relatively arranged porous substrate layers, and a catalytic layer arranged between the two porous substrate layers; wherein the catalytic layer comprises a ZIF-8-based porous carbon material and a single-atom catalyst; the ZIF-8-based porous carbon material is arranged in parallel between the two porous substrate layers, and two adjacent ZIF-8-based porous carbon materials form a confined channel in a direction perpendicular to the porous substrate layers, and the single-atom catalyst is loaded on the inner surface of the confined channel.

[0008] As a second aspect of the present invention, a method for preparing a confined channel membrane catalytic material is provided, comprising: adding a dimethylimidazole solution to a mixed solution formed by zinc nitrate and a metal acetylacetonate complex and mixing them evenly, performing a hydrothermal reaction to obtain a first precursor, the first precursor comprising a metal-doped ZIF-8 mixture; placing the first precursor in an inert gas atmosphere for calcination to obtain a second precursor, the second precursor comprising a ZIF-8-based porous carbon material and a single-atom catalyst loaded on the ZIF-8-based porous carbon material; adding the acidified second precursor to a surfactant solution and mixing them evenly, performing an activation treatment to introduce active groups on the surface of the ZIF-8-based porous carbon material to obtain a third precursor; evaporating and self-assembling the dispersion of the third precursor, and as the solvent in the dispersion evaporates, the activated ZIF-8-based porous carbon material self-assembles and arranges on the porous substrate layer to form a confined channel, thereby obtaining a confined channel membrane catalytic material.

[0009] As a third aspect of the present invention, there is provided an application of a confined channel membrane catalytic material in compound detection.

[0010] Based on the above technical solution, the present invention provides a confined channel membrane catalytic material and a preparation method and application thereof, which have at least one of the following beneficial effects.

[0011] (1) In the embodiment of the present invention, ZIF-8-based porous carbon materials are arranged in parallel between porous substrate layers to construct a regular and orderly confined channel structure, which confines the catalytic reaction to the nanoscale space, effectively reduces the reaction energy barrier, and significantly improves the catalytic efficiency. Compared with traditional catalytic systems, it can achieve a catalytic reaction with a high conversion rate under milder conditions. The single-atom catalyst is loaded on the inner surface of the confined channel, accurately positioning the active site, avoiding uneven dispersion of the catalyst, improving the selectivity and stability of the catalytic reaction, and reducing the occurrence of side reactions. The design of the two porous substrate layers and the intermediate catalytic layer allows the reaction solution to pass smoothly through the confined channel, while achieving timely separation from the catalyst to avoid catalyst loss. The porous substrate layer ensures the mechanical strength and permeability of the confined channel membrane catalytic material, which is conducive to fluid transmission. The confined channel membrane catalytic material (hereinafter referred to as membrane catalytic material) provided by the present invention solves the problem of low flux of traditional membrane-based confined channels, realizes high-throughput reactions, and has broad application prospects in the fields of chemical synthesis, environmental pollutant degradation, etc.

[0012] (2) In the embodiment of the present invention, the metal ions in the metal acetylacetonate complex are uniformly doped into the ZIF-8 structure through a hydrothermal reaction, laying the foundation for the subsequent formation of uniformly distributed single-atom catalysts, ensuring the uniformity of catalytic active sites, and effectively improving the catalytic efficiency and stability. The calcination process under an inert gas atmosphere promotes the conversion of ZIF-8 into a ZIF-8-based porous carbon material, while achieving in-situ generation of single-atom catalysts, simplifying the preparation process, and avoiding the problems of agglomeration and loss during the catalyst loading process. The acidification and activation treatment accurately introduces active groups on the surface of the porous carbon material, providing reaction sites for evaporation self-assembly, ensuring the controllability of the evaporation self-assembly process, and thus forming regular and orderly confined channels. The evaporation self-assembly process not only causes the activated ZIF-8-based porous carbon material to be oriented to form a high-throughput confined channel, reducing fluid transmission resistance, but also accurately fixes the single-atom catalyst in the channel, achieving efficient separation of the reaction solution and the catalyst, showing good application potential in the fields of chemical synthesis and environmental governance.

[0013] (3) In the embodiments of the present invention, when the confined channel membrane catalytic material provided by the present invention is applied to compound detection, its unique confined channel structure can significantly enrich the target compound and greatly improve the detection sensitivity; the single-atom catalyst loaded in the channel can undergo a specific catalytic reaction with the compound to be detected, enhancing the signal response and improving the detection accuracy. At the same time, the porous characteristics of the ZIF-8-based porous carbon material and the design of the catalytic layer and the porous substrate layer ensure the high permeability of the membrane catalytic material, allowing the test sample to quickly pass through the membrane catalytic material, achieving efficient and rapid detection. In addition, the confined channel membrane catalytic material is highly stable and reusable, effectively reducing the detection cost and providing a more efficient, sensitive and economical solution for compound detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of the confined channel membrane catalytic material in an embodiment of the present invention;

[0015] Figure 2 for Figure 1 Schematic diagram of the top view of the middle catalytic layer;

[0016] Figure 3 for Figure 1 Schematic diagram of the top view of the middle restricted channel;

[0017] Figure 4 for Figure 3 Schematic diagram of the part shown in 45° top view;

[0018] Figure 5 for Figure 1 Schematic diagram of the middle restricted channel;

[0019] Figure 6 for Figure 5 A magnified view of the details of area A;

[0020] Figure 7 This is a flow chart of a method for preparing a confined channel membrane catalytic material according to an embodiment of the present invention;

[0021] Figure 8 This is an optical photograph of the catalytic layer located on the nylon membrane prepared in Example 1 of the present invention;

[0022] Figure 9 This is a scanning electron microscope image of the catalyst layer surface in Example 1 of the present invention;

[0023] Figure 10 for Figure 9 A magnified view of the details of area B in the middle;

[0024] Figure 11 This is a transmission electron microscope image of the catalyst layer surface in Example 1 of the present invention;

[0025] Figure 12 for Figure 11 A magnified view of the details of the middle C area;

[0026] Figure 13 1 is a catalytic performance diagram of the embodiment and the comparative example in Example 1 of the present invention;

[0027] Figure 14 This is a diagram showing the catalytic performance of the confined channel membrane catalytic material under flow catalytic conditions in Example 1 of the present invention.

[0028] Description of reference numerals:

[0029] 100-porous base layer;

[0030] 200-catalytic layer;

[0031] 201-ZIF-8 based porous carbon materials;

[0032] 202-limited channel;

[0033] 203-Single-atom catalyst. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0035] In the process of realizing the concept of the present invention, it was found that the existing catalytic membrane materials have obvious deficiencies in terms of catalytic efficiency, active site distribution and separation performance. Traditional catalytic membranes have low catalytic efficiency due to the dispersion of active sites and uncontrollable reaction space; and it is difficult to separate the catalyst from the reaction solution after the reaction, making it difficult to reuse. In order to solve the above problems, the present invention proposes a confined channel membrane catalytic material and its preparation method and application based on the optimization of the catalytic reaction space and the catalyst loading method. By constructing a structure in which two porous substrate layers clamp the catalytic layer, a nanoscale confined channel is formed with parallel arranged ZIF-8-based porous carbon materials, and the catalytic reaction is confined to a regular space, effectively reducing the reaction energy barrier. At the same time, the single-atom catalyst is precisely loaded on the inner surface of the confined channel to achieve an orderly distribution of active sites, thereby enhancing catalytic activity and selectivity. The confined channel membrane catalytic material provided by the present invention realizes the synergistic optimization of catalytic reaction and separation of reaction solution, which not only improves the catalytic efficiency, but also facilitates catalyst recovery, providing an efficient and stable catalytic solution for the fields of chemical industry and environmental protection.

[0036] Figure 1 Schematic diagram of the structure of the confined channel membrane catalytic material in an embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the top view of the middle catalytic layer; Figure 3 for Figure 1 Schematic diagram of the top view of the middle restricted channel; Figure 4 for Figure 3 Schematic diagram of the part shown in 45° top view; Figure 5 for Figure 1 Schematic diagram of the middle restricted channel; Figure 6 for Figure 5 A magnified view of the details of area A.

[0037] As a first aspect of the present invention, a confined channel membrane catalytic material is provided, such as Figures 1-6As shown, it includes: two relatively arranged porous substrate layers 100, and a catalytic layer 200 arranged between the two porous substrate layers; wherein the catalytic layer includes a ZIF-8 based porous carbon material 201 and a single atom catalyst 203; the ZIF-8 based porous carbon material is arranged in parallel between the two porous substrate layers, and two adjacent ZIF-8 based porous carbon materials form a confined channel 202 in a direction perpendicular to the porous substrate layers, and the single atom catalyst 203 is loaded on the inner surface of the confined channel 202.

[0038] In the embodiment of the present invention, Figures 1-6 As shown, the ZIF-8-based porous carbon material 201 is arranged in parallel between the porous substrate layer 100, constructing a regular and orderly confined channel 202 structure, limiting the catalytic reaction to the nanoscale space, effectively reducing the reaction energy barrier, significantly improving the catalytic efficiency, and compared with the traditional catalytic system, a catalytic reaction with high conversion rate can be achieved under milder conditions. The single-atom catalyst 203 is loaded on the inner surface of the confined channel 202, accurately positioning the active sites, avoiding uneven dispersion of the catalyst, improving the selectivity and stability of the catalytic reaction, and reducing the occurrence of side reactions. The design of the two porous substrate layers 100 and the intermediate catalytic layer 200 allows the reaction solution to pass smoothly through the confined channel 202, while achieving timely separation from the catalyst to avoid catalyst loss, and the porous substrate layer 100 ensures the mechanical strength and permeability of the confined channel membrane catalytic material, which is conducive to fluid transmission. The confined channel membrane catalytic material provided by the present invention solves the problem of low flux of the traditional membrane-based confined channel, realizes high-throughput reaction, and has broad application prospects in the fields of chemical synthesis, environmental pollutant degradation, etc.

[0039] According to an embodiment of the present invention, the shape of the ZIF-8-based porous carbon material 201 includes a rhombic dodecahedron or a cube.

[0040] In an embodiment of the present invention, the regular geometric shape enables the ZIF-8-based porous carbon material 201 in the catalytic layer to be arranged in parallel more closely and orderly between the porous substrate layer 100, forming a uniform and stable confined channel 202 structure, effectively reducing the fluid transmission resistance, significantly improving the flux of the membrane catalyst material, and providing protection for the rapid passage of the reaction solution. At the same time, the rhombic dodecahedron or cubic structure has a large specific surface area, provides abundant loading sites for the single atom catalyst 203, increases the catalyst loading, improves the density of catalytic active centers, and thus enhances catalytic efficiency. In addition, the regular shape helps the membrane catalyst material to achieve accurate size control and morphological regulation during the preparation process, makes the pore size and distribution of the confined channel 202 more uniform, ensures the consistency of the catalytic reaction environment, effectively avoids the problem of low local reaction efficiency caused by channel size differences, and has good application stability and reliability.

[0041] According to an embodiment of the present invention, the single-atom catalyst 203 includes any one of a ruthenium single-atom catalyst, a platinum single-atom catalyst, a palladium single-atom catalyst, an iron single-atom catalyst, a cobalt single-atom catalyst, and a nickel single-atom catalyst.

[0042] In an embodiment of the present invention, these single-atom catalysts 203 have a unique electronic structure and crystal structure, which can provide efficient active sites for catalytic reactions, significantly reduce the reaction activation energy, and exhibit excellent catalytic performance in a variety of catalytic reactions. For example, ruthenium single-atom catalysts have extremely high catalytic activity and selectivity in some redox reactions; platinum single-atom catalysts have good catalytic effects on specific organic synthesis reactions. At the same time, they are loaded on the inner surface of the confined channel formed by the ZIF-8-based porous carbon material, which can avoid catalyst agglomeration and loss and extend the service life. Different types of single-atom catalysts can be selected for different target reactions, which greatly expands the application range of the confined channel membrane catalytic material. Whether in the fields of fine chemical synthesis, energy conversion, or environmental pollutant degradation, efficient catalysis can be achieved by rationally selecting single-atom catalysts 203, providing a diverse and flexible solution for practical applications.

[0043] According to an embodiment of the present invention, the porous base layer 100 is independently selected from any one of nylon membrane, cellulose membrane, chitosan membrane, polyimide membrane, polyacrylonitrile membrane, polyethersulfone membrane, polyvinylidene fluoride membrane, aluminum oxide membrane, titanium dioxide membrane, and silicon dioxide membrane.

[0044] In an embodiment of the present invention, a variety of porous substrate material selections can be adapted to different application scenarios and needs. For example, nylon membranes have good mechanical strength and chemical stability, and can ensure the structural integrity of membrane catalytic materials under high-intensity, corrosive environments; polyvinylidene fluoride membranes have excellent solvent resistance and antioxidant properties, and are suitable for catalytic reactions in organic solvent systems. These porous substrate layers 100 all have rich pore structures, which can effectively promote the rapid passage of reaction solutions, improve the flux of membrane catalytic materials, and provide a stable support structure for the catalytic layer 200 to ensure the stability of the confined channel 202 structure. In addition, inorganic material substrates such as aluminum oxide membranes and titanium dioxide membranes have unique surface properties and chemical activity, which can synergize with the catalytic layer to further improve the catalytic efficiency; and natural polymer material substrates such as cellulose membranes and chitosan membranes have good biocompatibility, which provides possibilities for applications in the fields of biocatalysis, drug synthesis, etc., greatly expanding the application range of confined channel membrane catalytic materials and meeting the diverse demands for membrane catalytic material performance in different fields.

[0045] According to an embodiment of the present invention, the width of the confined channel 202 is 1-3 nm; the particle size of the ZIF-8-based porous carbon material 201 is 450-550 nm; and the pore size of the porous base layer 100 is 50-300 nm.

[0046] In an embodiment of the present invention, the width of the confined channel 202 is controlled at 1-3 nm, forming a highly adapted nano-reaction space, effectively reducing the diffusion distance of the reactant molecules, strengthening the confinement effect, significantly reducing the reaction energy barrier, and improving the catalytic efficiency. The particle size of the ZIF-8-based porous carbon material 201 is 450-550 nm, ensuring stable arrangement between the porous substrate layer 100, forming a regular channel array, reducing fluid transmission resistance, and improving membrane flux. The pore size of the porous substrate layer 100 is 50-300 nm, which not only ensures the rapid passage of the reaction solution, but also provides stable support for the catalytic layer 200, preventing the catalytic layer 200 from collapsing and deforming, ensuring the stability of the overall structure of the membrane catalytic material, and realizing efficient and stable catalytic reactions.

[0047] Figure 7 This is a flow chart of the preparation method of the confined channel membrane catalytic material in an embodiment of the present invention.

[0048] As a second aspect of the present invention, a method for preparing a confined channel membrane catalytic material is provided, such as Figure 7 As shown, it includes steps S1 to S4.

[0049] Step S1: adding a dimethylimidazole solution to a mixed solution of zinc nitrate and a metal acetylacetonate complex and mixing them evenly, and then performing a hydrothermal reaction to obtain a first precursor, wherein the first precursor includes a metal-doped ZIF-8 mixture.

[0050] Step S2: calcining the first precursor in an inert gas atmosphere to obtain a second precursor, wherein the second precursor includes a ZIF-8-based porous carbon material and a single-atom catalyst supported on the ZIF-8-based porous carbon material.

[0051] Step S3: adding the acidified second precursor to a surfactant solution and mixing them evenly, performing an activation treatment to introduce active groups on the surface of the ZIF-8-based porous carbon material to obtain a third precursor.

[0052] Step S4: evaporating and self-assembling the dispersion of the third precursor. As the solvent in the dispersion evaporates, the activated ZIF-8-based porous carbon material self-assembles and arranges on the porous substrate layer to form confined channels, thereby obtaining a confined channel membrane catalytic material.

[0053] In an embodiment of the present invention, the metal ions in the metal acetylacetone complex are uniformly doped in the ZIF-8 structure through a hydrothermal reaction, laying the foundation for the subsequent formation of uniformly distributed single-atom catalysts, ensuring the uniformity of catalytic active sites, and effectively improving catalytic efficiency and stability. The calcination process under an inert gas atmosphere promotes the conversion of ZIF-8 into a ZIF-8-based porous carbon material, while realizing the in-situ generation of single-atom catalysts, simplifying the preparation process, and avoiding the problems of agglomeration and loss during the catalyst loading process. The acidification and activation treatments accurately introduce active groups on the surface of the porous carbon material, provide reaction sites for evaporation self-assembly, ensure the controllability of the evaporation self-assembly process, and thus form regular and orderly confined channels. The evaporation self-assembly process not only causes the activated ZIF-8-based porous carbon material to be oriented to form a high-throughput confined channel, reducing fluid transmission resistance, but also accurately fixes the single-atom catalyst in the channel, realizing efficient separation of the reaction solution and the catalyst, and showing good application potential in the fields of chemical synthesis and environmental governance.

[0054] According to an embodiment of the present invention, the metal acetylacetonate complex includes any one of ruthenium acetylacetonate, platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate.

[0055] In an embodiment of the present invention, the acetylacetonato group has good coordination ability and thermal stability. In the hydrothermal reaction, the complex formed with the metal ion can be stably dispersed in the solution system, ensuring that the metal ions are uniformly doped in the ZIF-8 structure, laying the foundation for the subsequent formation of a uniformly distributed single-atom catalyst. During the calcination process under an inert gas atmosphere, the acetylacetonato group decomposes, and the released metal ions react with the nitrogen source to generate a single-atom catalyst in situ, and are accurately loaded in the ZIF-8-based porous carbon material. This in situ generation mechanism not only avoids the problems of catalyst agglomeration and shedding in the traditional loading method, but also achieves accurate control of the particle size and distribution of the single-atom catalyst, so that it fits closely to the inner surface of the confined channel to form an efficient active site. In addition, the single-atom catalysts generated by the corresponding acetylacetonato metal complexes of different types each have a unique electronic structure and catalytic activity, which can be flexibly selected for different reaction requirements, greatly expanding the application scenarios of confined channel membrane catalytic materials and improving the catalytic performance and adaptability of membrane catalytic materials.

[0056] In an embodiment of the present invention, during the hydrothermal reaction, dimethylimidazole can undergo ligand exchange reaction with the metal ions in zinc ion and metal acetylacetonate complex. The zinc ion in zinc nitrate is combined with dimethylimidazole, and the metal ion in metal acetylacetonate complex also gradually forms a coordination bond with dimethylimidazole, and then begins to form the nucleus of metal-organic framework. Along with the reaction, on the nucleus surface, more zinc ions, metal ions and dimethylimidazole continue to coordinate, grow according to the crystal structure of ZIF-8, and gradually form metal-doped ZIF-8 crystals. Meanwhile, the ions in the solution continuously diffuse to the crystal surface and participate in the reaction, so that the crystal is continuously grown.

[0057] According to an embodiment of the present invention, the temperature of the hydrothermal reaction is 100-140°C and the time is 3-5 hours. The appropriate temperature range provides sufficient energy for the reaction, accelerates the movement speed and reaction rate of the ions, enables the zinc ions and dimethylimidazole to react more quickly, and is conducive to the formation of ZIF-8 crystals; it also enables the metal ions in the metal acetylacetonate complex to be more stably doped into the ZIF-8 crystal lattice. Within the appropriate time, the zinc ions and dimethylimidazole can fully coordinate to form a sufficient number of crystal nuclei, and the crystal nuclei gradually grow into complete ZIF-8 crystals, while ensuring that the metal ions are evenly doped into the crystal structure.

[0058] Furthermore, the concentration of zinc nitrate in the mixed solution is 0.1-0.5 mol / L, the molar ratio of zinc nitrate to the metal acetylacetonate complex is 10-50:1, the concentration of the dimethylimidazole solution is 0.1-2 mol / L, and the molar ratio of zinc nitrate to dimethylimidazole is 1:1-4.

[0059] In an embodiment of the present invention, during the calcination process, the ZIF-8 structure in the first precursor will undergo thermal decomposition and carbonization, the organic ligand will gradually be converted into porous carbon, and the metal ions will react with the nitrogen source in the system (from nitrogen-containing substances such as dimethylimidazole) to generate a single-atom catalyst. At the same time, the single-atom catalyst will be evenly loaded on the formed ZIF-8-based porous carbon material.

[0060] According to an embodiment of the present invention, the temperature of calcination is 900-1000 ℃, and the time is 1-3h. Within a suitable temperature range, it is conducive to the full carbonization of the organic ligand of ZIF-8, forming a porous carbon material with a rich pore structure, providing a large specific surface area and a good mass transfer channel for subsequent catalytic reactions. At the same time, it can also promote the metal ions to react with the nitrogen source to generate single-atom catalysts, and contribute to the uniform dispersion and stable existence of the single-atom catalysts in the porous carbon material. Within a suitable time, it can ensure that the carbonization of ZIF-8 and the generation reaction of the single-atom catalyst are fully carried out, so that the organic ligand is completely converted into porous carbon, the metal ions are completely converted into single-atom catalysts, and the uniform loading of the single-atom catalysts in the porous carbon material is achieved.

[0061] In an embodiment of the present invention, impurities and unstable groups remaining on the surface of ZIF-8 based porous carbon material are removed by acidification, the surface of ZIF-8 based porous carbon material is purified, and a clean surface environment is provided for subsequent reactions. Secondly, the chemical property of the surface of ZIF-8 based porous carbon material can be adjusted by acidification so that the surface is rich in acidic functional groups such as carboxyl and hydroxyl. The introduction of these functional groups increases the activity of the surface of ZIF-8 based porous carbon material, improves its adsorption capacity to materials such as surfactants and single-atom catalysts, and contributes to the uniform dispersion of subsequent surfactants and the stable load of catalyst. In addition, acidification can also appropriately corrode the surface of ZIF-8 based porous carbon material, increase surface roughness, further increase the specific surface area of ZIF-8 based porous carbon material, for the construction of active sites and the carrying out of catalytic reaction create more favorable conditions.

[0062] According to embodiments of the present invention, the acidification temperature is 70-90°C for 8-16 hours, which can precisely control the number and type of active groups on the surface of the ZIF-8-based porous carbon material, providing ideal conditions for subsequent evaporation self-assembly. In some specific embodiments, the acid solution used during the acidification is a 0.5 mol / L sulfuric acid solution or a 1 mol / L hydrochloric acid solution.

[0063] In an embodiment of the present invention, during the activation process, hexadecyltrimethylammonium bromide (CTAB) can be selected as a surfactant. CTAB interacts with the acidic groups on the surface of the acidified ZIF-8-based porous carbon material. CTAB is a cationic surfactant whose positively charged head group can bind to the negatively charged acidic groups through electrostatic attraction. The positively charged CTAB molecules can generate electrostatic repulsion with the positively charged single-atom catalyst, effectively preventing catalyst aggregation during the activation process and ensuring its uniform dispersion on the surface of the ZIF-8-based porous carbon material, fully exposing the active sites and improving catalytic efficiency.

[0064] According to an embodiment of the present invention, the activation reaction temperature is 20-30°C and the time is 0.5-1h, which can effectively activate the active groups on the surface of the ZIF-8-based porous carbon material without destroying the structure of the ZIF-8-based porous carbon material. In some specific embodiments, the concentration of CTAB is 0.5-1.5mmol / L. The appropriate concentration of CTAB can form a stable molecular layer on the surface of the ZIF-8-based porous carbon material. During the evaporation self-assembly process, it guides the ZIF-8-based porous carbon material to arrange in an orderly manner, accurately controls the structure and size of the confined channel, ensures the uniformity of the channel width, reduces the fluid transmission resistance, achieves high throughput, and enhances the stability and repeatability of the catalytic reaction.

[0065] In an embodiment of the present invention, during the evaporative self-assembly process, as the solvent evaporates, self-assembly occurs between the surfactant molecules. Because the surfactant molecules have a hydrophilic head and a hydrophobic tail, they tend to form ordered structures, such as micelles or liquid crystal phases. In this process, the interactions between the surfactant molecules (such as hydrophobic interactions, hydrogen bonds, etc.) will promote the orderly arrangement of the ZIF-8-based porous carbon material, forming confined channels between adjacent ZIF-8-based porous carbon materials.

[0066] According to an embodiment of the present invention, the temperature for evaporative self-assembly is 70-90°C. Evaporative self-assembly is performed at 70-90°C to ensure that the solvent evaporates at an appropriate rate, allowing the ZIF-8-based porous carbon material to be orderly arranged to form regular confined channels, ultimately obtaining a confined channel membrane catalytic material with excellent performance and stable structure, effectively improving the catalytic efficiency and reusability of the membrane catalytic material.

[0067] According to an embodiment of the present invention, the solvents used in the dimethylimidazole solution and the mixed solution are both methanol. Methanol, as a solvent, can provide a suitable environment for the reaction. By precisely controlling the reaction conditions, such as reactant concentration, reaction temperature and time, ZIF-8 with a dodecahedral structure or a cubic structure can be formed. These two structures have unique physical and chemical properties. The dodecahedral structure helps to increase the specific surface area of the membrane catalytic material and improve the adsorption performance; the cubic structure can optimize the pore structure of the membrane catalytic material, which is beneficial to material transport and diffusion, thereby showing excellent application prospects in the fields of gas adsorption, separation and catalysis, and providing strong support for the development of related technologies.

[0068] As a third aspect of the present invention, there is provided an application of a confined channel membrane catalytic material in compound detection.

[0069] In an embodiment of the present invention, when the confined channel membrane catalytic material provided by the present invention is applied to compound detection, its unique confined channel structure can significantly enrich the target compound and greatly improve the detection sensitivity; the single-atom catalyst loaded in the channel can undergo a specific catalytic reaction with the compound to be tested, thereby enhancing the signal response and improving the detection accuracy. At the same time, the porous characteristics of the ZIF-8-based porous carbon material and the design of the catalytic layer and the porous base layer ensure the high permeability of the material, so that the test sample can quickly pass through the membrane catalytic material to achieve efficient and rapid detection. In addition, the confined channel membrane catalytic material is highly stable and reusable, effectively reducing the detection cost and providing a more efficient, sensitive and economical solution for compound detection.

[0070] The present invention is further illustrated below by examples and related test experiments. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments can also be implemented without these specific details. Moreover, in the case of no conflict, the details in the following embodiments can be arbitrarily combined into other feasible embodiments. All instruments, consumables and reagents in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0071] Example 1

[0072] In this Example 1, a confined channel membrane catalytic material was prepared and its structure was characterized and related tests were performed. The specific preparation process is described as follows.

[0073] Preparation of the first precursor: Dissolve 1.904 g of zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and 84.9 mg of ruthenium acetylacetonate (Ru(acac)₃) in 20 mL of methanol to form Solution A. Dissolve 2.1 g of dimethylimidazole in 40 mL of methanol to form Solution B. Quickly pour Solution B into Solution A and stir continuously for 10 minutes. The mixed solution is then transferred to a 100 mL polytetrafluoroethylene-lined container, placed in a hydrothermal reactor, and reacted at 120°C for 4 hours. After the reaction, cool to room temperature, collect the precipitate by centrifugation, rinse three times with methanol, and dry overnight in a vacuum oven at 60°C to obtain the first precursor, designated Ru / ZIF-8.

[0074] Preparation of the second precursor: The first precursor powder was placed in a magnetic boat, heated to 950°C at a rate of 5°C / min in a tube furnace, and kept at this temperature for 2 hours. After cooling to room temperature, the second precursor was obtained, which was recorded as DA. Ru / NC .

[0075] Preparation of the third precursor: The second precursor powder was dissolved in a 0.5M dilute sulfuric acid solution and stirred in an 80°C oil bath for 12 hours. After the solution cooled to room temperature, it was centrifuged and washed three times with deionized water and dried in a vacuum oven at 60°C overnight. The obtained powder was redissolved in deionized water and ultrasonicated for 1 hour. The upper black solution was filtered and then redispersed in a 0.5mmol / mL CTAB solution. It was shaken with an oscillator for 30 minutes and stirred at room temperature for 1 hour. It was then centrifuged and washed three times with deionized water and dried in a vacuum oven at 60°C overnight to obtain the third precursor, which was recorded as CTAB-DA. Ru / NC .

[0076] Construction of confined channels: First, place a 30mm×30mm×1mm glass slide on the filter bottle, place a nylon membrane with a pore size of 0.2μm on the glass slide, place a filter cup with a diameter of 1.5cm on the nylon membrane, and clamp the filter bottle and filter cup with a clamp to prevent leakage. The obtained third precursor powder is re-ultrasonic dispersed in water to obtain a 1mg / mL dispersion. Use a pipette to transfer 2mL of the above dispersion into the filter cup, and then place the filter bottle and filter cup together in an 80℃ oven for evaporation and self-assembly until the solution evaporates completely, remove the filter cup, and obtain a catalytic layer assembled on the nylon membrane. Superimpose a layer of nylon membrane on the catalytic layer to obtain a confined channel membrane catalytic material.

[0077] Catalytic performance testing of the confined channel membrane catalyst material: A nylon membrane was superimposed on the catalytic layer, and the filter cup and filter flask were clamped to prevent leakage. 500 μL of 5 mmol / L 3,3',5,5'-tetramethylbenzidine (TMB) and 4.5 mL of 0.2 mol / L acetic acid-sodium acetate buffer solution (pH 4.4) were mixed and poured into the filter cup. The vacuum filtration device was activated, and the solution was passed through the confined channel membrane catalyst material under vacuum pressure. The solution at the bottom of the filter flask was collected and measured for UV absorbance. A catalytic experiment was also conducted by placing the confined channel membrane catalyst material directly in a mixture of TMB and acetic acid-sodium acetate buffer solution as a control.

[0078] Figure 8 This is an optical photograph of the catalytic layer located on the nylon membrane prepared in Example 1 of the present invention; Figure 9 This is a scanning electron microscope image of the catalyst layer surface in Example 1 of the present invention; Figure 10 for Figure 9 A magnified view of the details of area B in the middle; Figure 11 This is a transmission electron microscope image of the catalyst layer surface in Example 1 of the present invention; Figure 12 for Figure 11 Enlarged detail of area C in the middle.

[0079] from Figures 8-12As can be seen from the figure, individual ZIF-8-based porous carbon materials have relatively consistent shapes and sizes, and the distance between adjacent ZIF-8-based porous carbon materials is stable. The ZIF-8-based porous carbon materials are evenly and orderly arranged, with confined channels formed between adjacent ZIF-8-based porous carbon materials. The catalytic layer formed by multiple ZIF-8-based porous carbon materials is relatively regular and uniform, without obvious unevenness such as localized accumulation or vacancies.

[0080] Figure 13 1 is a catalytic performance diagram of the embodiment and the comparative example in Example 1 of the present invention; Figure 14 This is a diagram showing the catalytic performance of the confined channel membrane catalytic material under flow catalytic conditions in Example 1 of the present invention.

[0081] from Figure 13-14 It can be seen that the conventional solution incubation method cannot achieve the timely separation of the catalyst and the reaction solution, and will continue to catalyze the TMB color development reaction, making the absorbance of the solution unstable. The confined channel membrane catalytic material prepared by the present invention can achieve the effect of timely separation of the reaction solution and the catalyst on the one hand, and on the other hand, it can enhance the catalytic activity by relying on the confined channel, and can complete the reaction within 10 seconds that requires more than 30 minutes of conventional solution incubation. After the colorless TMB flows through the membrane catalytic material, it turns into blue oxidized state TMB. The amount of the reaction solution is changed to test the absorbance of the obtained solution and calculate the flux. The absorbance remains basically unchanged with the change of the solution volume, indicating that the confined channel has continuous catalytic ability and the reaction solution does not damage the structure of the membrane catalytic material after flowing through. The average flux of the membrane catalytic material is calculated to be 14297 L·m -2 ·h -1 bar -1 This value is much larger than that reported in the prior art (<150 L·m -2 ·h -1 bar -1 ), the performance is improved by two orders of magnitude.

[0082] Furthermore, the confined channel membrane catalytic material provided by the present invention can be used to analyze and detect absorbance changes during the redox process of a chromogenic substrate driven by a nanozyme. For example, substances that can generate hydrogen peroxide (H2O2) to facilitate TMB oxidation (glucose oxidase, cholesterol oxidase, D-amino acid oxidase, etc.) can also be used to detect reducing substances that inhibit TMB oxidation, such as ascorbic acid, glutathione, cysteine, dopamine, acid phosphatase, alkaline phosphatase, and α-glucosidase. The chromogenic agent 3,3',5,5'-tetramethylbenzidine (TMB) used in this example can be replaced with o-phenylenediamine (OPD) or ABTS (2,2-azino-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt).

[0083] In summary, the present invention proposes a confined channel membrane catalytic material, in which the confined channel is formed by self-assembly of a ZIF-8-based porous carbon material, and the surfaces of two ZIF-8-based porous carbon materials are arranged in parallel to each other, forming a confined channel consistent with the direction of liquid flow. By rationally regulating the single-atom catalyst loaded on the surface of the ZIF-8-based porous carbon material in the early stage, the catalytic active sites on both sides of the confined channel can be precisely customized. On the one hand, the confined channel can achieve highly selective and efficient catalytic reactions by precisely positioning the active sites. On the other hand, the confined channel parallel to the fluid direction can be used to achieve ultrafast liquid flow with a high flux, and the average flux is greater than 14,000 L·m -2 ·h -1 bar -1 , which is two orders of magnitude higher than the best result reported previously.

[0084] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A confined channel membrane catalytic material, characterized in that: include: Two porous substrate layers disposed opposite to each other, and a catalytic layer disposed between the two porous substrate layers; Wherein, the catalytic layer comprises ZIF-8 based porous carbon material and single atom catalyst; The ZIF-8-based porous carbon material is arranged in parallel between the two porous substrate layers, and two adjacent ZIF-8-based porous carbon materials form a confined channel in a direction perpendicular to the porous substrate layers, and the single-atom catalyst is loaded on the inner surface of the confined channel.

2. The membrane catalytic material according to claim 1, characterized in that The shape of the ZIF-8-based porous carbon material includes a rhombic dodecahedron or a cube.

3. The membrane catalytic material according to claim 1, characterized in that The single-atom catalyst includes any one of a ruthenium single-atom catalyst, a platinum single-atom catalyst, a palladium single-atom catalyst, an iron single-atom catalyst, a cobalt single-atom catalyst, and a nickel single-atom catalyst.

4. The membrane catalytic material according to claim 1, characterized in that The porous substrate layer is independently selected from any one of nylon membrane, cellulose membrane, chitosan membrane, polyimide membrane, polyacrylonitrile membrane, polyethersulfone membrane, polyvinylidene fluoride membrane, aluminum oxide membrane, titanium dioxide membrane and silicon dioxide membrane.

5. The membrane catalytic material according to claim 1, characterized in that The width of the confined channel is 1-3 nm; The particle size of the ZIF-8-based porous carbon material is 450-550 nm; The pore size of the porous base layer is 50-300 nm.

6. A method for preparing a confined channel membrane catalytic material according to any one of claims 1 to 5, characterized in that: include: Adding a dimethylimidazole solution to a mixed solution of zinc nitrate and a metal acetylacetonate complex and mixing them evenly, and then performing a hydrothermal reaction to obtain a first precursor, wherein the first precursor includes a metal-doped ZIF-8 mixture; calcining the first precursor in an inert gas atmosphere to obtain a second precursor, wherein the second precursor includes a ZIF-8-based porous carbon material and a single-atom catalyst supported on the ZIF-8-based porous carbon material; adding the acidified second precursor to a surfactant solution and mixing them evenly, and then performing an activation treatment to introduce active groups on the surface of the ZIF-8-based porous carbon material to obtain a third precursor; The dispersion of the third precursor is evaporated and self-assembled. As the solvent in the dispersion evaporates, the activated ZIF-8-based porous carbon material self-assembles and arranges on the porous substrate layer to form confined channels, thereby obtaining a confined channel membrane catalytic material.

7. The preparation method according to claim 6, characterized in that The metal acetylacetonate complex includes any one of ruthenium acetylacetonate, platinum acetylacetonate, palladium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate.

8. The preparation method according to claim 6, characterized in that The temperature of the hydrothermal reaction is 100-140° C., and the time of the hydrothermal reaction is 3-5 hours; The calcination temperature is 900-1000°C, and the calcination time is 1-3h; The acidification temperature is 70-90°C, and the acidification time is 8-16h; The activation reaction temperature is 20-30°C, and the activation reaction time is 0.5-1h; The temperature of the evaporation self-assembly is 70-90°C.

9. The preparation method according to claim 6, characterized in that The solvents used in the dimethylimidazole solution and the mixed solution are both methanol.

10. Use of the confined channel membrane catalytic material according to any one of claims 1 to 5 in compound detection.

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