Bimetal MOF / MXene composite material as well as preparation method and application thereof

Abstract

The invention provides a bimetallic MOF / MXene composite material as well as a preparation method and application thereof, and relates to the technical field of catalysts. In the bimetal MOF / MXene composite material provided by the invention, the bimetal MCuFe-MOF is constructed by CuFe2O4 (at) MIL-100 (Fe, Cu) with a core-shell heterojunction, so that the generation and directional migration of photo-induced electrons are facilitated. According to the invention, a cocatalyst MXene is introduced into the composite material to form a Schottky junction, and the Schottky junction plays a role of a photo-induced electron trap in a photo-Fenton process, so that the charge separation efficiency is improved. Besides, a three-dimensional microsphere structure formed by the cocatalyst MXene provides a larger specific surface area, the dispersity of the MCuFe-MOF is improved, adsorption and mass transfer of organic pollutants are facilitated, and the degradation performance on the organic pollutants is excellent.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a bimetallic MOF / MXene composite material and a preparation method and application thereof. Background Art

[0002] Dye wastewater is a typical organic pollutant that is difficult to degrade. Due to its deep color, it hinders aquatic plants from absorbing light, which is not conducive to photosynthesis, and then leads to a decrease in dissolved oxygen in the water, which harms the growth and reproduction of aquatic plants and animals, which will form a vicious cycle in the water environment. Due to the complex molecular structure and chemical resistance of dyes, dyes are one of the most challenging pollutants that need to be treated.

[0003] Fenton reaction is a commonly used technical means to treat organic pollutants in water. Bimetallic MOF (Metal-organic Framework) has become a hot topic in the field of photo-Fenton because of its bimetallic active center, adjustable pore size, high specific surface area, excellent photocatalytic performance and good thermal stability. 3+ / Fe 2+ The defects of slow circulation, narrow pH range, difficulty in recycling and reusing the catalyst, rapid recombination of photogenerated electron-hole pairs and degradation efficiency need to be further improved, making the photo-Fenton catalyst of bimetallic MOF still difficult to apply industrially. Therefore, it is imperative to develop more efficient, green and easy-to-separate catalysts from wastewater.

[0004] The prior art discloses a composite Schottky photocatalyst Ti 3 C 2 MXene / NH 2 -MIL-88B(Fe), NH 2 -MIL-88B grows in situ on MXene to construct Schottky junctions, avoids the agglomeration of MOF, increases the effective area of ​​the composite material, and acts as a photogenerated electron trap during the photocatalytic process, improving the charge separation efficiency of MOF. This material can be used to eliminate and degrade pollutants in water. Larger dye molecules are mainly adsorbed on the catalyst surface, and smaller dye molecules can diffuse into the catalyst to produce a certain adsorption effect. However, when the MXene addition ratio is 0.125, Fe is not only adsorbed on the surface of MXene, but also enters the middle layer of MXene during the reaction to grow, blocking further growth. However, the limited surface area of ​​MXene with a two-dimensional layered structure and the limited adsorption sites for cationic dye pollutants MB affect the degradation rate of MB.

[0005] The prior art prepared low-crystalline bimetallic MOFs of MIL-53 (Fe, M) (M: Mn or Cu) as photo-Fenton catalysts for the degradation of ciprofloxacin (CIP). The prior art found that the preparation of bimetallic or multimetallic MOFs in a low-crystalline state is a feasible strategy to enhance the synergistic effect between heterogeneous metal nodes in the photo-Fenton system. In addition to the increase of low-crystalline metals (CUSs), both Cu and Mn can increase the specific surface area, promote visible light absorption and separation / transport of low-crystalline carriers, thereby accelerating the Fe 3+ / Fe 2+ and Mn 3+ / Mn 2+ circulation, which is beneficial to H 2 O 2 activation.

[0006] The prior art discloses a method of using bimetallic NH 2 -MIL-88B(Fe, Mn)(FM88B) was used as raw material, perylene diimide (PDI) was modified by ammonolysis reaction, and a heterojunction structure based on Fe-Mn bimetallic MOFs and PDI was constructed in a photo-Fenton system to achieve effective separation of photogenerated electron-hole pairs in Fe-Mn bimetallic MOFs and directional and rapid transmission of photogenerated electrons.

[0007] The above-mentioned prior art adopts the heterogeneous photocatalytic-Fenton synergistic process. The heterogeneous photocatalytic material excites and generates photogenerated electrons, which promotes Fe 3+ / Fe 2+ However, the application of the above-mentioned prior art heterogeneous photo-Fenton method still faces the problem of unsatisfactory efficiency of photogenerated electron transfer in the catalyst, Fe 3+ / Fe 2+ The circulation rate is slow and the degradation activity for organic pollutants is not high enough. Summary of the invention

[0008] In view of this, the object of the present invention is to provide a bimetallic MOF / MXene composite material and a preparation method and application thereof. The bimetallic MOF / MXene composite material provided by the present invention has excellent photocatalytic activity for photo-Fenton reaction to degrade organic pollutants.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a bimetallic MOF / MXene composite material, comprising MXene microspheres and MCuFe-MOF, wherein the MXene microspheres are located on the surface of the MCuFe-MOF, or the MCuFe-MOF is located on the surface of the MXene microspheres; the MXene microspheres comprise PMMA microspheres and a MXene shell located on the surface of the PMMA microspheres; the MCuFe-MOF has a 3D core-shell structure, and the core is CuFe 2 O 4 , the shell is made of MIL-100 (Fe, Cu) material.

[0011] The present invention also provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, which is prepared by a hydrogen bond self-assembly method, comprising the following steps:

[0012] The initiator, polymethylpyrrolidone, MCuFe-MOF, methyl methacrylate and alcohol solvent are mixed to carry out polymerization reaction to obtain MCuFe-MOF@PMMA microspheres;

[0013] The MCuFe-MOF@PMMA microspheres, a single layer of MXene and water are mixed, MXene is self-assembled on the surface of MCuFe-MOF@PMMA through hydrogen bonds, and MXene is wrapped on the surface of MCuFe-MOF@PMMA to obtain the bimetallic MOF / MXene composite material.

[0014] Preferably, the preparation method of MCuFe-MOF comprises the following steps: 2 O 4 The nanoparticles, trimesic acid and ethanol aqueous solution are mixed and subjected to a solvothermal reaction to obtain MCuFe-MOF.

[0015] The present invention also provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, which is prepared by a solvothermal method, comprising the following steps: 2 O 4 The nanoparticles, trimesic acid and an alcohol aqueous solution are mixed and subjected to a solvothermal reaction to obtain the bimetallic MOF / MXene composite material.

[0016] The present invention also provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, which is prepared by an in-situ growth method, comprising the following steps: PMMA@MXene microspheres, CuFe 2 O 4 The nanoparticles, trimesic acid and lower alcohol are mixed, and MCuFe-MOF is in situ grown on the surface of PMMA@MXene to obtain the bimetallic MOF / MXene composite material.

[0017] Preferably, the method for preparing PMMA@MXene microspheres comprises the following steps: mixing an aqueous dispersion of PMMA microspheres and Ti 3 C 2 T x The colloidal solutions were mixed and surface hydrogen bonding self-assembled to obtain PMMA@MXene microspheres.

[0018] The present invention also provides the use of the bimetallic MOF / MXene composite material described in the above technical scheme or the bimetallic MOF / MXene composite material prepared by the preparation method described in the above technical scheme as a catalyst in degrading organic pollutants.

[0019] Preferably, the method of degrading organic pollutants includes degrading organic pollutants by photo-Fenton reaction.

[0020] Preferably, the organic pollutant comprises methylene blue.

[0021] Preferably, the mass ratio of the bimetallic MOF / MXene composite material to the organic pollutant is 1:0.05-4.

[0022] The bimetallic MOF / MXene composite material provided by the present invention degrades the dye MB in a heterogeneous photo-Fenton system, and uses MCuFe-MOF as the main catalyst and MXene as the co-catalyst to construct a bimetallic core-shell CuFe 2 O 4 @MIL-100 (Fe, Cu) heterojunction MCuFe-MOF. MCuFe-MOF has a regular nearly spherical morphology and a 3D core-shell structure, which is conducive to substrate adsorption and diffusion mass transfer. CuFe 2 O 4 The photothermal effect promotes the generation and separation of photogenerated carriers by forming a heterojunction with MIL-100 (Fe, Cu), thus achieving Fe 2+ There are two active centers of Fe and Cu in MCuFe-MOF. 2+ and Cu + Both can catalyze H 2 O 2 ·OH is generated. In addition, the synergistic effect of Fe and Cu in the bimetallic MCuFe-MOF is enhanced, which improves the light absorption ability and promotes Fe 3+ / Fe 2+ , Cu 2+ / Cu + Self-circulation and degradation rate.

[0023] There are two active centers of Fe and Cu in MCuFe-MOF. 3+ / Fe2+ , Cu 2+ / Cu + The continuous and efficient cycle of binary redox couples enhances the photo-Fenton reaction activity and reduces H 2 O 2 Dosage.

[0024] In the present invention, the MCuFe-MOF material itself constructs a heterojunction, and the photothermal effect promotes the Fe 2+ cycle; the in situ growth of MCuFe-MOF on MXene microspheres can improve the dispersibility and stability of MCuFe-MOF; the main catalyst MCuFe-MOF and the co-catalyst MXene construct a Schottky junction, which acts as a photogenerated electron trap in the photo-Fenton process and improves the charge separation efficiency.

[0025] In the bimetallic MOF / MXene composite material provided by the present invention, MCuFe-MOF has a core-shell heterojunction, which is conducive to the generation and directional migration of photogenerated electrons. The present invention also introduces a cocatalyst MXene into the composite material, and the cocatalyst MXene serves as the structural skeleton of the bimetallic CuFe-MOF to construct a Schottky junction (MCuFe-MOF and Ti 3 C 2 T x ), which acts as a photogenerated electron trap in the photo-Fenton process, improving the charge separation efficiency and carrier separation efficiency. In addition, the three-dimensional microsphere structure formed by the co-catalyst MXene provides a larger specific surface area, improves the dispersibility of MCuFe-MOF, and is conducive to the adsorption and mass transfer of organic pollutants, and has excellent degradation performance for organic pollutants.

[0026] MXene is a 3D microsphere structure with a high specific surface area. It can be used as a growth matrix for catalysts and as a structural support for semiconductor self-assembly or in-situ growth to prevent the overlapping and stacking of 2D MXene nanosheets of catalyst components (such as MXene nanosheets) and increase the exposure of more active sites, thereby improving the photo-Fenton catalytic performance of bimetallic MOF / MXene composites. At the same time, MXene has excellent conductivity and acts as an electron capture center and charge separation medium.

[0027] Under light conditions, MCuFe-MOF can generate photogenerated electrons (e - ) and photogenerated holes (h + ) cooperates with the hot electrons generated by its photothermal conversion to promote Fe 3+ / Fe 2+ , improving the photo-Fenton efficiency.

[0028] The MCuFe-MOF with a mesoporous structure has a larger specific surface area, making it easier to expose active centers. The 3D microsphere structure is conducive to mass transfer and light capture, and has better catalytic performance. Moreover, the bimetallic MOF / MXene composite material is a magnetic material, which is conducive to magnetic separation and recovery.

[0029] The present invention uses PMMA microspheres as templates, wraps MXene on the surface of PMMA through hydrogen bonds to achieve the construction of MXene three-dimensional structure, synthesizes PMMA@MXene microspheres, constructs Schottky junctions (MCuFe-MOF and MXene), accelerates interfacial electron transmission, and promotes Fe 3+ and Cu 2+ The rapid reduction improves the Fenton reaction efficiency and has excellent photo-Fenton catalytic activity.

[0030] The present invention adopts hydrogen bond self-assembly method, solvent thermal method and in-situ growth method to prepare bimetallic MOF / MXene composite materials. The present invention adopts different preparation methods to construct a variety of bimetallic MOF / MXene composite materials with 3D microsphere structures. The preparation method of the bimetallic MOF / MXene composite material provided by the present invention is simple to operate, simple in process, low in cost, and suitable for industrial production.

[0031] The existing one-step solvothermal method has a high temperature (150°C), which makes it difficult to ensure the stability of the bimetallic MOF / MXene composite structure and the consistency of particle morphology. 2 O 4 and Cu are partially oxidized, and there is no good degradation effect. The bimetallic MOF / MXene composite material constructed by the room temperature in-situ growth method of the present invention maintains a spherical three-dimensional structure, the prepared composite material has a high specific surface area, promotes the mass transfer of organic pollutants, and has a simple preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 XRD spectra of DL-MXene, MCuFe-MOF, MCuFe-MOF@PMMA and hydrogen-bonded self-assembled MCuFe-MOF@PMMA@MXene microspheres in Example 1;

[0033] Figure 2 XRD of PMMA@MXene, MCuFe-MOF and solvothermal MCuFe-MOF / PMMA@MXene microspheres in Example 2;

[0034] Figure 3 XRD of PMMA@MXene and in-situ grown MCuFe-MOF / PMMA@MXene microspheres in Example 3;

[0035] Figure 4SEM images of PMMA microspheres (left) and PMMA@MXene microspheres (right) in Example 2;

[0036] Figure 5 SEM images of MCuFe-MOF (left) and MCuFe-MOF@PMMA microspheres (right) in Example 1;

[0037] Figure 6 This is the SEM image of MCuFe-MOF@PMMA@MXene microspheres produced by hydrogen bond self-assembly in Example 1;

[0038] Figure 7 This is the SEM image of the MCuFe-MOF / PMMA@MXene microspheres prepared by the solvothermal method in Example 2;

[0039] Figure 8 This is the SEM image of the MCuFe-MOF / PMMA@MXene microspheres grown by the in-situ method in Example 3;

[0040] Fig. 9 N is the N of MCuFe-MOF / PMMA@MXene microspheres grown by in-situ method in Example 3 2 Adsorption-desorption curve

[0041] Fig.10 This is the pore size distribution curve of the MCuFe-MOF / PMMA@MXene microspheres grown by the in-situ method in Example 3;

[0042] Fig.11 The performance diagram of the photo-Fenton catalyst for MB degradation using hydrogen-bonded self-assembled MCuFe-MOF@PMMA@MXene microspheres, MCuFe-MOF@PMMA and MCuFe-MOF in Example 1;

[0043] Fig.12 Performance diagram of photo-Fenton degradation of MB by in-situ growth method MCuFe-MOF / PMMA@MXene microspheres, MCuFe-MOF and PMMA@MXene in Example 3;

[0044] Fig.13 H 2 O 2 The effect of the addition amount on the degradation of MB by in-situ growth method MCuFe-MOF / PMMA@MXene microspheres;

[0045] Fig.14 The degradation curves of MB under different conditions.

[0046] Fig.15 This is the degradation curve of MCuFe-MOF / PMMA@MXene grown by the in situ method in Example 3 for low concentration (50 mg / L) MB.

[0047] Fig.16 This is the degradation curve of MCuFe-MOF / PMMA@MXene grown by the in situ method in Example 3 for low concentration (1 g / L) MB. DETAILED DESCRIPTION

[0048] The present invention provides a bimetallic MOF / MXene composite material, comprising MXene microspheres and MCuFe-MOF, wherein the MXene microspheres are located on the surface of the MCuFe-MOF, or the MCuFe-MOF is located on the surface of the MXene microspheres; the MXene microspheres comprise PMMA microspheres and a MXene shell located on the surface of the PMMA microspheres; the MCuFe-MOF has a 3D core-shell structure, and the core is CuFe 2 O 4 , the shell is made of MIL-100 (Fe, Cu) material.

[0049] The present invention adopts hydrogen bond self-assembly method, solvent thermal method and in-situ growth method to prepare bimetallic MOF / MXene composite materials. The present invention adopts different preparation methods to construct a variety of bimetallic MOF / MXene composite materials with 3D microsphere structures.

[0050] The following is an explanation of the preparation of bimetallic MOF / MXene (MCuFe-MOF@PMMA@MXene) by hydrogen bond self-assembly method.

[0051] The present invention also provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, comprising the following steps:

[0052] The initiator, polymethylpyrrolidone, MCuFe-MOF, methyl methacrylate and alcohol solvent are mixed to carry out polymerization reaction to obtain MCuFe-MOF@PMMA microspheres;

[0053] The MCuFe-MOF@PMMA microspheres, a single layer of MXene and water are mixed and hydrogen bond self-assembled to obtain the bimetallic MOF / MXene composite material.

[0054] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0055] The invention mixes an initiator, polymethylpyrrolidone (PVP), MCuFe-MOF, methyl methacrylate (MMA) and an alcohol solvent, and performs a polymerization reaction to obtain MCuFe-MOF@PMMA microspheres.

[0056] In the present invention, the initiator preferably includes azobisisobutyronitrile (AIBN). In the present invention, the mass ratio of the initiator to MCuFe-MOF is preferably 1:10 to 15, and in specific embodiments may be 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15.

[0057] In the present invention, the mass ratio of the MCuFe-MOF to polymethylpyrrolidone is preferably 1:3-4, and in specific embodiments may be 1:3, 1:3.5 or 1:4.

[0058] In the present invention, the ratio of the mass of the MCuFe-MOF to the volume of methyl methacrylate is preferably 1 g: 10.5-10.7 mL, and in specific embodiments may be 1 g: 10.5 mL, 1 g: 10.6 mL or 1 g: 10.7 mL.

[0059] In the present invention, the alcohol solvent preferably includes methanol. In the present invention, the ratio of the mass of the MCuFe-MOF to the volume of the alcohol solvent is preferably 1 g:100-120 mL, and in specific embodiments may be 1 g:100 mL, 1 g:110 mL or 1 g:120 mL.

[0060] In the present invention, the mixing preferably includes: stirring and mixing the initiator, polymethylpyrrolidone, MCuFe-MOF and alcohol solvent, and then adding methyl methacrylate for mixing. In the present invention, the stirring and mixing temperature is preferably room temperature, and the stirring and mixing time is preferably 30 to 35 minutes, and in specific embodiments, it can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes or 35 minutes.

[0061] In the present invention, the polymerization temperature is preferably 54-56°C, and in a specific embodiment, it can be 54°C, 55°C or 56°C; the polymerization time is preferably 24-26h, and in a specific embodiment, it can be 24h, 25h or 26h; the polymerization is preferably carried out under a protective atmosphere, and the protective atmosphere preferably includes nitrogen, argon or helium. In the present invention, during the polymerization reaction, PMMA is polymerized on the surface of MCuFe-MOF to obtain MCuFe-MOF@PMMA microspheres.

[0062] After completing the polymerization reaction, the present invention preferably further comprises: centrifuging the reaction system obtained by the polymerization reaction, washing the obtained solid component with water and then drying it to obtain MCuFe-MOF@PMMA microspheres. In the present invention, the number of water washings is preferably 3 to 4 times. In the present invention, the drying temperature is preferably 58 to 62°C, and in a specific embodiment it can be 58°C, 60°C or 62°C; the present invention has no special limitation on the drying time, and it can be dried to constant weight.

[0063] In the present invention, the preparation method of the MCuFe-MOF preferably comprises the following steps:

[0064] CuFe 2 O 4 The nanoparticles, trimesic acid and ethanol aqueous solution are mixed and subjected to a solvothermal reaction to obtain MCuFe-MOF.

[0065] In the present invention, the CuFe 2 O 4 Nanoparticles and trimesic acid (H 3 The mass ratio of BTC) is preferably 1:1-2, and in specific embodiments it can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.

[0066] In the present invention, the CuFe 2 O 4 The ratio of the mass of the nanoparticles to the volume of the ethanol aqueous solution is preferably 1g:320-340mL, and in specific embodiments can be 1g:320mL, 1g:330mL, 1g:333mL or 1g:340mL. In the present invention, the volume fraction of ethanol in the ethanol aqueous solution is preferably 40-60%.

[0067] In the present invention, the temperature of the solvothermal reaction is preferably 130-170°C, and in specific embodiments, it can be 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C or 170°C; the time of the solvothermal reaction is preferably 10-14h, and in specific embodiments, it can be 10h, 11h, 12h, 13h or 14h. In the present invention, during the solvothermal reaction, CuFe 2 O 4 The nanoparticles were subjected to in situ surface pyrolysis and complexed with trimesic acid to obtain MCuFe-MOF with a mesoporous structure.

[0068] After completing the solvothermal reaction, the present invention preferably further comprises: using a magnet to collect the solid components obtained by the solvothermal reaction, washing with water and then drying to obtain MCuFe-MOF. In the present invention, the water washing is preferably deionized water washing; the number of water washings is preferably 3 to 4 times. In the present invention, the drying temperature is preferably 50 to 70°C, and in specific embodiments it can be 50°C, 60°C or 70°C. The present invention has no special limitation on the drying time, and drying to constant weight is sufficient; the drying preferably includes vacuum drying.

[0069] In the present invention, the CuFe 2 O 4 The method for preparing the nanoparticles preferably comprises the following steps: mixing an iron ion source, a copper ion source, ethylene glycol, sodium acetate and polyethylene glycol, and performing a solvent thermal reduction reaction to obtain CuFe 2 O 4 Nanoparticles.

[0070] In the present invention, the iron ion source preferably includes FeCl 3 6H 2 In the present invention, the copper ion source preferably includes CuCl 2 ·H 2 In the present invention, the molar ratio of iron in the iron ion source to copper in the copper ion source is preferably 1:0.2-0.8, and in specific embodiments may be 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7 or 1:0.8.

[0071] In the present invention, the ratio of the amount of the iron ion source to the volume of ethylene glycol is preferably 1 mol: 7 to 9 L, and in specific embodiments, it can be 1 mol: 7 L, 1 mol: 7.5 L, 1 mol: 8 L, 1 mol: 8.5 L or 1 mol: 9 L. In the present invention, ethylene glycol is added as a reducing agent to convert FeCl 3 Reduction to Fe 3 O 4 .

[0072] In the present invention, the mass ratio of the iron ion source to sodium acetate is preferably 1:2-3, and in specific embodiments, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.5, 1:2.67, 1:2.7, 1:2.8, 1:2.9 or 1:3. The present invention adds sodium acetate for electrostatic stabilization to prevent particle agglomeration, which helps the ethylene glycol-mediated FeCl 3 Reduction to Fe 3 O 4 .

[0073] In the present invention, the mass ratio of the iron ion source to the polyethylene glycol is preferably 1:0.5-1, and in specific embodiments can be 1:0.5, 1:0.6, 1:0.7, 1:0.74, 1:0.8, 1:0.9 or 1:1. The present invention adds polyethylene glycol as a surfactant and prevents particles from agglomerating.

[0074] In the present invention, the mixing of the iron ion source, the copper ion source, ethylene glycol, sodium acetate and polyethylene glycol preferably comprises: dissolving the iron ion source and the copper ion source in ethylene glycol to obtain an iron-copper mixed ion solution, and mixing the iron-copper mixed ion solution, sodium acetate and polyethylene glycol. In the present invention, the mixing time of the iron-copper mixed ion solution, sodium acetate and polyethylene glycol is preferably 25 to 35 minutes, and in a specific embodiment can be 25 minutes, 28 minutes, 30 minutes, 32 minutes or 35 minutes; the mixing is preferably stirring mixing.

[0075] In the present invention, the temperature of the solvent thermal reduction reaction is preferably 180-220°C, and in specific embodiments it can be 180°C, 190°C, 200°C, 210°C or 220°C. The time of the solvent thermal reduction reaction is preferably 6-10h, and in specific embodiments it can be 6h, 7h, 8h, 9h or 10h.

[0076] After the solvent thermal reduction reaction is completed, the present invention preferably further comprises: using a magnet to collect the solid components obtained by the solvent thermal reduction reaction, washing with deionized water and then drying to obtain CuFe 2 O 4 Nanoparticles. In the present invention, the drying temperature is preferably 50-70°C, and in specific embodiments can be 50°C, 60°C or 70°C. The present invention has no special limitation on the drying time, and drying to constant weight is sufficient; the drying preferably includes vacuum drying.

[0077] After obtaining the MCuFe-MOF@PMMA microspheres, the present invention mixes the MCuFe-MOF@PMMA microspheres, a single layer of MXene and water to perform hydrogen bond self-assembly to obtain the CuFe-MOF@PMMA@MXene composite material.

[0078] In the present invention, the mixing preferably includes: mixing the MCuFe-MOF@PMMA microsphere aqueous dispersion and the monolayer MXene aqueous dispersion. In the present invention, the concentration of the MCuFe-MOF@PMMA microsphere aqueous dispersion is preferably 9.5 to 10.5 g / L, and in a specific embodiment it can be 9.5 g / L, 10 g / L or 10.5 g / L. In the present invention, the concentration of the monolayer MXene aqueous dispersion is preferably 2.4 to 2.6 g / L, and in a specific embodiment it can be 2.4 g / L, 2.5 g / L or 2.6 g / L.

[0079] In the present invention, the mass ratio of the MCuFe-MOF@PMMA microspheres and the monolayer MXene is preferably 9.5-10.5:2.4-2.6, and in specific embodiments it can be 9.5:2.4, 9.5:2.5, 9.5:2.6, 10:2.4, 10:2.5, 10:2.6, 10.5:2.4, 10.5:2.5 or 10.5:2.6.

[0080] In the present invention, the temperature of the hydrogen bond self-assembly is preferably room temperature; the time of the hydrogen bond self-assembly is preferably 40 to 45 minutes, and in a specific embodiment, it can be 40 minutes, 41 minutes, 42 minutes, 43 minutes, 44 minutes or 45 minutes; the hydrogen bond self-assembly is preferably carried out under stirring conditions. In the present invention, during the hydrogen bond self-assembly process, MXene self-assembles on the surface of MCuFe-MOF@PMMA through hydrogen bonds to synthesize MCuFe-MOF@PMMA@MXene microspheres.

[0081] After completing the hydrogen bond self-assembly, the present invention preferably further comprises: centrifugally washing the reaction system obtained by the hydrogen bond self-assembly and freeze-drying it to obtain the bimetallic MOF / MXene composite material. In the present invention, the number of centrifugal washings is preferably 2 to 3 times; the speed of the centrifugal washing is preferably 8000 to 8500 r / min, and in a specific embodiment it can be 8000 r / min, 8100 r / min, 8200 r / min, 8300 r / min, 8400 r / min or 8500 r / min. The present invention does not specifically limit the freeze-drying conditions, and freeze-drying is sufficient.

[0082] In the present invention, the method for preparing the monolayer MXene preferably comprises the following steps: LiF, HCl aqueous solution and Ti 3 AlC 2 After mixing, etching and ultrasonic exfoliation were performed to obtain a single layer of MXene.

[0083] In the present invention, the ratio of the mass of LiF to the molar amount of HCl in the HCl aqueous solution is preferably 1g:125-160mmol, and in specific embodiments, it can be 1g:125mmol, 1g:130mmol, 1g:135mmol, 1g:140mmol, 1g:145mmol, 1g:150mmol, 1g:155mmol or 1g:160mmol. In the present invention, the concentration of the HCl aqueous solution is preferably 10-12M (mol / L), and in specific embodiments, it can be 10M, 10.5M, 11M, 11.5M or 12M.

[0084] In the present invention, the LiF and Ti 3 AlC 2 The mass ratio is preferably 1:0.6-0.7, and in specific embodiments it can be 1:0.6, 1:0.61, 1:0.62, 1:0.63, 1:0.64, 1:0.65, 1:0.66, 1:0.67, 1:0.68, 1:0.69 or 1:0.7.

[0085] In the present invention, the LiF, HCl aqueous solution and Ti 3 AlC 2 The mixing preferably comprises: adding LiF to the HCl solution, stirring to mix, and then adding Ti 3 AlC 2 In the present invention, the stirring and mixing temperature is preferably room temperature, and the stirring and mixing time is preferably 12 to 18 minutes, and in specific embodiments, it can be 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes or 18 minutes.

[0086] In the present invention, the etching temperature is preferably 35-40°C, and in specific embodiments it can be 35°C, 36°C, 37°C, 38°C, 39°C or 40°C; the etching time is preferably 45-50h, and in specific embodiments it can be 45h, 46h, 47h, 48h, 49h or 50h.

[0087] After completing the etching, the present invention preferably further comprises: subjecting the mixed solution obtained by the etching to a first centrifugal separation, washing the obtained solid component with an HCl aqueous solution, a LiCl aqueous solution and deionized water in sequence until the pH value is 5 to 7, and subjecting the last deionized water washing solution to vacuum freeze drying to obtain a multilayer MXene (ML-MXene). In the present invention, the rotation speed of the first centrifugal separation is preferably 3400 to 3600 r / min, and in a specific embodiment, it can be 3400 r / min, 3500 r / min or 3600 r / min; the time of the first centrifugal separation is preferably 4 to 6 min, and in a specific embodiment, it can be 4 min, 5 min or 6 min. In the present invention, the concentration of the HCl aqueous solution for washing is preferably 0.5 to 1 M, and in a specific embodiment, it can be 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M or 1 M. In the present invention, the concentration of the LiCl aqueous solution for washing is preferably 0.5 to 1 M, and in a specific embodiment it can be 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M or 1 M. In the present invention, the number of times of washing with HCl aqueous solution, washing with LiCl aqueous solution and washing with deionized water is independently preferably 3 to 4 times. In a specific embodiment of the present invention, the pH value can be 5, 5.5, 6, 6.5 or 7. In the present invention, the drying is -75 to -85°C, and in a specific embodiment it can be -75°C, -80°C or -85°C; the present invention has no special limitation on the drying time, and drying to constant weight is sufficient, such as drying for 72 hours; the drying preferably includes vacuum freeze drying.

[0088] In the present invention, the ultrasonic exfoliation is preferably to ultrasonically exfoliate the multilayer MXene (ML-MXene) dispersion under a protective atmosphere. In the present invention, the temperature of the ultrasonic treatment is preferably room temperature, the power of the ultrasonic treatment is preferably 500-700W, and in a specific embodiment, it can be 500W, 550W, 600W, 650W or 700W; the time of the ultrasonic treatment is preferably 40-50min, and in a specific embodiment, it can be 40min, 45min or 50min; the protective atmosphere preferably includes argon or helium.

[0089] After completing the ultrasonic stripping, the present invention preferably further comprises subjecting the ultrasonic stripping solution to a second centrifugal separation, and freeze-drying the obtained supernatant to obtain a monolayer MXene (DL-MXene). In the present invention, the rotation speed of the second centrifugal separation is preferably 8000-8500 r / min, and in specific embodiments, it can be 8000 r / min, 8100 r / min, 8200 r / min, 8300 r / min, 8400 r / min or 8500 r / min; the time of the second centrifugal separation is preferably 5-6 min, and in specific embodiments, it can be 5 min, 5.5 min or 6 min. The present invention does not specifically limit the time of the freeze-drying, and it can be dried to constant weight.

[0090] The following is an explanation of the solvothermal preparation of bimetallic MOF / MXene composite materials (MCuFe-MOF / PMMA@MXene).

[0091] The present invention provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, comprising the following steps: 2 O 4 The nanoparticles, trimesic acid and an alcohol aqueous solution are mixed and subjected to a solvothermal reaction to obtain the bimetallic MOF / MXene composite material.

[0092] In the present invention, the PMMA@MXene microspheres and CuFe 2 O 4 The mass ratio of the nanoparticles is preferably 100:0.12-0.18, and in specific embodiments may be 100:0.12, 100:0.13, 100:0.14, 100:0.15, 100:0.16, 100:0.17 or 100:0.18.

[0093] In the present invention, the PMMA@MXene microspheres and trimesic acid (H 3 The mass ratio of BTC) is preferably 100:0.220-0.230, and in specific embodiments can be 100:0.220, 100:0.222, 100:0.225, 100:0.228 or 100:0.230.

[0094] In the present invention, the alcohol in the alcohol aqueous solution preferably includes ethanol; the volume fraction of the alcohol in the alcohol aqueous solution is preferably 30-50%, and in a specific embodiment it can be 30%, 35%, 40%, 45% or 50%. In the present invention, the ratio of the mass of PMMA@MXene microspheres to the volume of the alcohol aqueous solution is preferably 100g:45-55mL, and in a specific embodiment it can be 100g:45mL, 100g:50mL or 100g:55mL.

[0095] In the present invention, the temperature of the solvothermal reaction is preferably 145-155°C, and in specific embodiments, it can be 145°C, 148°C, 150°C, 152°C, or 155°C; the time of the solvothermal reaction is preferably 11-13h, and in specific embodiments, it can be 12h. The present invention adopts a solvothermal method, introduces PMMA@MXene microspheres in the process of preparing MCuFe-MOF, and loads MCuFe-MOF on the surface of PMMA@MXene microspheres.

[0096] After completing the solvothermal reaction, the present invention preferably further comprises: subjecting the reaction system obtained by the solvothermal reaction to magnetic separation, washing the obtained solid components with water and then drying, to obtain the bimetallic MOF / MXene composite material. In the present invention, the magnetic separation is preferably magnet separation. In the present invention, the number of water washings is preferably 3 to 4 times. In the present invention, the drying temperature is preferably 50 to 70°C, and in specific embodiments it can be 50°C, 60°C or 70°C. The present invention has no special limitation on the drying time, and drying to constant weight is sufficient; the drying preferably includes vacuum drying.

[0097] In the present invention, the method for preparing PMMA@MXene microspheres preferably comprises the following steps: mixing an aqueous dispersion of PMMA microspheres and Ti 3 C 2 T x The MXene colloidal solution was mixed and coated to obtain PMMA@MXene microspheres.

[0098] In the present invention, the concentration of the aqueous dispersion of PMMA microspheres is preferably 8 to 12 mg / mL, and in specific embodiments, it can be 8 mg / mL, 9 mg / mL, 10 mg / mL, 11 mg / mL or 12 mg / mL; the aqueous dispersion of PMMA microspheres is preferably subjected to ultrasonic treatment before use, and the ultrasonic treatment time is preferably 9 to 12 minutes, and in specific embodiments, it can be 9 minutes, 10 minutes, 11 minutes or 12 minutes. In the present invention, the Ti 3 C 2 T xThe concentration of the MXene colloidal solution is preferably 2 to 3 g / L, and in specific embodiments may be 2 g / L, 2.2 g / L, 2.5 g / L, 2.8 g / L or 3 g / L. 3 C 2 T x The volume ratio of the MXene colloidal solution is preferably 10:3.5-4.5, and in specific embodiments may be 10:3.5, 10:3.8, 10:4, 10:4.2 or 10:4.5.

[0099] In the present invention, the coating temperature is preferably room temperature, the coating time is preferably 18 to 30 min, and in specific embodiments it can be 18 min, 20 min, 22 min, 25 min, 28 min or 30 min; the coating is preferably carried out under stirring conditions, and the stirring speed is preferably 500 to 600 r / min, and in specific embodiments it can be 500 r / min, 550 r / min or 600 r / min.

[0100] After the coating is completed, the present invention preferably further comprises: centrifuging the coating system obtained by the coating, washing the obtained solid component with water and then drying it to obtain PMMA@MXene microspheres. In the present invention, the number of water washings is preferably 3 to 4 times. In the present invention, the drying temperature is preferably 50 to 70°C, and in specific embodiments it can be 50°C, 60°C or 70°C. The present invention has no special limitation on the drying time, and drying to constant weight is sufficient; the drying preferably includes vacuum drying.

[0101] The present invention uses PMMA microspheres as templates, wraps MXene on the surface of PMMA through hydrogen bonds to achieve the construction of MXene three-dimensional structure, and synthesizes PMMA@MXene microspheres.

[0102] In the present invention, the PMMA microspheres are preferably prepared by a polymerization method, and the specific steps are as follows: an initiator, polymethylpyrrolidone (PVP), methyl methacrylate (MMA) and an alcohol solvent are mixed and subjected to a polymerization reaction to obtain PMMA microspheres.

[0103] In the present invention, the initiator preferably includes azobisisobutyronitrile (AIBN). In the present invention, the volume ratio of the methyl methacrylate to the mass ratio of the initiator is preferably 10.5-10.7 mL: 0.1-0.3 g, and in specific embodiments, it can be 10.5 mL: 0.1 g, 10.6 mL: 0.1 g, 10.7 mL: 0.1 g, 10.5 mL: 0.2 g, 10.6 mL: 0.2 g, 10.7 mL: 0.2 g, 10.5 mL: 0.3 g, 10.6 mL: 0.3 g or 10.7 mL: 0.3 g.

[0104] In the present invention, the volume ratio of methyl methacrylate to the mass ratio of polymethylpyrrolidone is preferably 10.5-10.7 mL: 0.1-4 g. In specific embodiments, it can be 10.5 mL: 0.1 g, 10.6 mL: 0.1 g, 10.7 mL: 0.1 g, 10.5 mL: 0.5 g, 10.6 mL: 0.5 g, 10.7 mL: 0.5 g, 10.5 mL: 1 g, 10.6 mL: 1 g, 10.7 mL: 1 g, 10.5 mL: 2 g, 10.6 mL: 2 g, 10.7 mL: 2 g, 10.5 mL: 3 g, 10.6 mL: 3 g, 10.7 mL: 3 g, 10.5 mL: 4 g, 10.6 mL: 4 g or 10.7 mL: 4 g.

[0105] In the present invention, the alcohol solvent preferably includes methanol. In the present invention, the volume ratio of the methyl methacrylate to the alcohol solvent is preferably 10.5-10.7:110, and in a specific embodiment can be 10.5:110, 10.6:110 or 10.7:110.

[0106] In the present invention, the mixing preferably comprises: stirring and mixing the initiator, polymethylpyrrolidone and alcohol solvent, and then adding methyl methacrylate for mixing. In the present invention, the stirring and mixing temperature is preferably room temperature, and the stirring and mixing time is preferably 30 to 35 minutes, and in a specific embodiment, it can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes or 35 minutes. In the present invention, the methyl methacrylate is preferably added with bubbling of a protective atmosphere; the protective atmosphere preferably comprises nitrogen, argon or helium.

[0107] In the present invention, the polymerization reaction temperature is preferably 54-56°C, and in a specific embodiment it can be 54°C, 55°C or 56°C; the polymerization reaction time is preferably 24-26h, and in a specific embodiment it can be 24h, 25h or 26h; the polymerization reaction is preferably carried out under a protective atmosphere, and the protective atmosphere preferably includes nitrogen, argon or helium.

[0108] After completing the polymerization reaction, the present invention preferably further comprises: centrifuging the reaction system obtained by the polymerization reaction, washing the obtained solid component with water and then drying it to obtain PMMA microspheres. In the present invention, the number of water washings is preferably 3 to 4 times. In the present invention, the drying temperature is preferably 58 to 62°C, and in a specific embodiment it can be 58°C, 60°C or 62°C; the present invention has no special limitation on the drying time, and it can be dried to constant weight.

[0109] The following is an explanation of the in situ growth method for preparing bimetallic MOF / MXene composite materials (MCuFe-MOF / PMMA@MXene).

[0110] The present invention provides a method for preparing the bimetallic MOF / MXene composite material described in the above technical solution, comprising the following steps: 2 O 4 The nanoparticles, trimesic acid and lower alcohol are mixed, and MCuFe-MOF is in situ grown on the surface of PMMA@MXene microspheres to obtain the bimetallic MOF / MXene composite material.

[0111] In the present invention, the PMMA@MXene microspheres and CuFe 2 O 4 The mass ratio of the nanoparticles is preferably 50:749-751, and in specific embodiments may be 50:749, 50:750 or 50:751.

[0112] In the present invention, the lower alcohol preferably includes methanol.

[0113] In the present invention, the mixing temperature is preferably room temperature; the mixing preferably includes: ultrasonically dispersing PMMA@MXene microspheres in lower alcohol to obtain a PMMA@MXene microsphere alcohol dispersion, adding CuFe 2 O 4The nanoparticles are first stirred and mixed to obtain a mixed solution; the mixed solution is secondly stirred and mixed with the alcohol solution of trimesic acid. In the present invention, the ratio of the mass of the PMMA@MXene microspheres to the volume of the lower alcohol is preferably 50g:98~101L, and in specific embodiments, it can be 50g:98L, 50g:99L, 50g:100L or 50g:101L. In the present invention, the ultrasonic dispersion is 10~13min, and in specific embodiments, it can be 10min, 11min, 12min or 13min. In the present invention, the time of the first stirring and mixing is preferably 30~32min, and in specific embodiments, it can be 30min, 31min or 32min. In the present invention, the ratio of the mass of trimesic acid to the volume of the lower alcohol in the alcohol solution of trimesic acid is preferably 0.8g:99~101L, and in specific embodiments, it can be 0.8g:99L, 0.8g:100L or 0.8g:101L. In the present invention, the rotation speed of the second stirring and mixing is preferably 500-600 r / min, and in a specific embodiment can be 500 r / min, 550 r / min or 600 r / min; the present invention has no special limitation on the time of the second stirring and mixing, as long as the raw materials can be mixed evenly.

[0114] In the present invention, the temperature of the in-situ growth is preferably room temperature; the time of the in-situ growth is preferably 23 to 25 hours, and in a specific embodiment, it can be 23 hours, 24 hours or 25 hours; the in-situ growth is preferably carried out under stirring conditions, and the stirring speed is preferably 500 to 600 r / min, and in a specific embodiment, it can be 500 r / min, 550 r / min or 600 r / min. In the present invention, during the in-situ growth process, MCuFe-MOF grows in-situ on the surface of PMMA@MXene.

[0115] After the in-situ growth is completed, the present invention preferably further comprises: centrifugally washing the reaction system obtained by the in-situ growth and then freeze-drying to obtain the bimetallic MOF / MXene composite material. In the present invention, the number of centrifugal washing is preferably 3 to 4 times. The present invention has no special restrictions on the freeze-drying conditions, and freeze-drying is sufficient.

[0116] The present invention also provides the use of the bimetallic MOF / MXene composite material described in the above technical solution or the bimetallic MOF / MXene composite material obtained by the preparation method described in the above technical solution as a catalyst in the degradation of organic pollutants. In the present invention, the method of degrading organic pollutants preferably includes photo-Fenton reaction to degrade organic pollutants. In the present invention, the organic pollutant preferably includes methylene blue (MB). In the present invention, the mass ratio of the bimetallic MOF / MXene composite material and the organic pollutant is preferably 1:0.05-4, and in a specific embodiment it can be 1:0.05, 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.

[0117] The photo-Fenton reaction of the bimetallic MOF / MXene composite material provided by the present invention to degrade organic pollutants works as follows: (1) The presence of Fe-O and Cu-O clusters in the bimetallic MCuFe-MOF makes the catalyst have visible light absorption characteristics, in which a ligand-metal charge transfer (LMCT) process occurs, and the photogenerated electrons are conducted through MXene, inhibiting carrier recombination. (2) Under light irradiation, CuFe 2 O 4 and MIL-100(Fe,Cu) are excited, CuFe 2 O 4 The photothermal effect of the core transfers the “hot electrons” to the surface of the MIL-100 (Fe, Cu) shell and then is absorbed by H 2 O 2 Capture and generate OH. At the same time, it significantly promotes Fe 3+ Reduction to Fe 2+ . Fe in MCuFe-MOF 2+ and Cu + The chemically reduced valence state can react with H 2 O 2 The reaction generates active OH, which is beneficial for the degradation of difficult-to-degrade pollutants in water. (3) MCuFe-MOF improves Fe 3+ / Fe 2+ , Cu 2+ / Cu + The continuous and efficient cycle of binary redox couples enhances the photo-Fenton reaction activity and reduces H 2 O 2Dosage. ④MXene can be used as a structural support. Due to the electrostatic driving force, MCuFe-MOF particles are attached to the surface of PMMA@MXene microspheres to form a catalyst with a 3D microsphere structure. When MCuFe-MOF and PMMA@MXene are composited, due to the different work functions of the two, an interfacial electric field is generated, resulting in band bending and enhancing the Schottky contact of the interface. Accelerate interfacial electron transfer, and its redox potential meets the conditions for complete degradation of MB. At the same time, MXene acts as a co-catalyst to provide electron capture traps, which accelerates the separation rate of photogenerated electron-hole pairs of MCuFe-MOF. After the dye MB is adsorbed on the catalyst surface, the multi-effect synergy, the interfacial interaction force formed between different components, such as the built-in electric field formed by the Schottky contact, not only reduces the energy barrier and forms an electron transmission channel, but also has a promoting effect on the photo-Fenton reaction process. More electrons are prompted to participate in the photo-Fenton reaction to solve the above-mentioned technical problem of degrading MB. The bimetallic MOF / MXene composite material provided by the present invention has high catalytic activity for the degradation of organic pollutants by the photo-Fenton reaction.

[0118] Moreover, the bimetallic MOF / MXene composite material provided by the present invention has high magnetism and structural stability, and the composite material can be recovered by magnetic separation, with a high reuse rate.

[0119] In order to further illustrate the present invention, the bimetallic MOF / MXene composite material provided by the present invention and its preparation method and application are described in detail below in combination with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0120] Example 1

[0121] Bimetallic MOF / MXene composites (MCuFe-MOF@PMMA@MXene) were prepared by hydrogen bond self-assembly method.

[0122] Preparation of DL-MXene: Pour 5.46 g LiF into 70 mL 12 M HCl aqueous solution and stir at room temperature for 15 min to obtain a mixed solution. 3 AlC 2 Slowly add it to the mixed solution, stir at 38°C for 48h, centrifuge at 3500r / min for 5min, and discard the supernatant. Wash with 1M HCl aqueous solution 3-4 times, 1M LiCl aqueous solution 3-4 times, and deionized water 3-4 times until pH = 6, take the last deionized water wash, pass argon ultrasound for 45min, centrifuge at 8000r / min for 5min, collect the supernatant, and freeze-dry to obtain a single-layer MXene (DL-MXene).

[0123] CuFe 2O 4 Preparation of nanoparticles: FeCl 3 6H 2 O (1.35 g, 5 mmol) and CuCl 2 ·H 2 A mixture of 1,4-dihydro-1,4-dihydro-2-nitropropene (0.426 g, 2.5 mmol) and 1,0-dihydro-1,4-dihydro-2-nitropropene (0.426 g, 2.5 mmol) was dissolved in 40 mL of ethylene glycol to form a transparent solution. Then 3.6 g of NaAc and 1.0 g of polyethylene glycol were added, stirred at 550 r / min for 30 min, transferred to a Teflon-lined reactor, and kept at 200 °C for 8 h. The solid product was collected with a magnet, washed with deionizers for 3 to 4 times, and dried in a vacuum oven at 60 °C to constant weight to obtain CuFe 2 O 4 Nanoparticles.

[0124] Preparation of MCuFe-MOF: 150 mg CuFe 2 O 4 Nanoparticles and 225 mg H 3 BTC was mixed with 50 mL of ethanol aqueous solution (ethanol volume fraction was 50%), transferred to a Teflon-lined reactor, and kept at 150°C for 12 h. The solid product was collected with a magnet, washed with deionized water 3 to 4 times, and dried in a vacuum at 60°C to constant weight to obtain MCuFe-MOF.

[0125] Preparation of MCuFe-MOF@PMMA microspheres: 0.1 g azobisisobutyronitrile (AIBN), 4.0 g polymethylpyrrolidone (PVP), 1 g MCuFe-MOF and 110 mL methanol were stirred for 30 min, and then 10.6 mL methyl methacrylate (MMA) was added and heated under N 2 The mixture was protected and stirred at 55°C for 24 h, centrifuged at 8000 r / min for 5 min, the solid components were collected, washed with deionized water for 3 to 4 times, and dried at 60°C to constant weight to obtain MCuFe-MOF@PMMA microspheres.

[0126] Preparation of bimetallic MOF / MXene composite material (MCuFe-MOF@PMMA@MXene) by hydrogen bond self-assembly method: 10mL 10mg / mL MCuFe-MOF@PMMA microsphere aqueous dispersion and 4mL 2.5DL-MXene dispersion were mixed and stirred for 40min, centrifuged and washed twice at 8000r / min, and freeze-dried for 24h to obtain MCuFe-MOF@PMMA@MXene composite material. The water was deionized water.

[0127] Example 2

[0128] Solvothermal preparation of bimetallic MOF / MXene composites (MCuFe-MOF / PMMA@MXene)

[0129] Preparation of PMMA microspheres: 0.1 g of azoisobutyronitrile (AIBN) and 4.0 g of polymethylpyridone (PVP) were dissolved in 110 mL of methanol and stirred for 30 min. Then 10.6 mL of methyl methacrylate monomer (MMA) was added and the mixture was stirred at N 2 The mixture was stirred at 55° C. for 24 h under protection and centrifuged at 8000 r / min for 5 min. The solid components were collected and washed with deionized water for 3 to 4 times to obtain PMMA microspheres. The PMMA microspheres were dispersed in deionized water to obtain a PMMA ball dispersion with a concentration of 10 mg / mL, and the dispersion was sonicated for 10 min before use.

[0130] Preparation of PMMA@MXene microspheres: 10 mL of 10 mg / mL PMMA sphere dispersion was mixed with 4 mL of 2.5 mg / mL Ti 3 C 2 T x The MXene colloidal solution was stirred at 550 r / min for 20 min and centrifuged at 8000 r / min for 5 min. The solid components were collected, washed with deionized water for 3 to 4 times, and vacuum dried at 60 °C to constant weight to obtain PMMA@MXene microspheres.

[0131] Preparation of bimetallic MOF / MXene composites (MCuFe-MOF / PMMA@MXene) by solvothermal method: 150 mg of CuFe prepared in Example 1 was added to 2 O 4 、100gPMMA@MXene microspheres、225mg H 3 BTC was mixed with 50 mL of ethanol aqueous solution (ethanol volume fraction was 50%), and the mixture was transferred to a Teflon-lined reactor and kept reacting at 150 °C for 12 h. The solid product was collected with a magnet, washed with deionized water for 3 to 4 times, and vacuum dried at 60 °C to constant weight to obtain MCuFe-MOF / PMMA@MXene.

[0132] Example 3

[0133] Preparation of bimetallic MOF / MXene composites (MCuFe-MOF / PMMA@MXene) by in situ growth method

[0134] 50 mg of PMMA@MXene microspheres prepared in Example 2 were dispersed in 100 mL of methanol and ultrasonically dispersed for 10 min. 750 mg of CuFe prepared in Example 1 was added. 2 O 4 , stirred for 30 min to obtain solution A. 800 mg H3 BTC was dissolved in 100 mL of methanol to obtain solution B. Solution B was poured into solution A, stirred at 550 r / min for 24 h, centrifuged at 8000 r / min, and then centrifuged and washed 3 to 4 times with deionized water. The obtained solid component was freeze-dried to obtain MCuFe-MOF / PMMA@MXene microspheres.

[0135] Test Example 1

[0136] Chemical composition analysis of bimetallic MOF / MXene composite microspheres prepared by different methods

[0137] X-ray powder diffractometer (XRD): XRD is used to characterize the crystal structure of the sample. The powder sample with uniform particle size after grinding is spread in a groove of suitable size and flattened, and then placed in the sample testing room for testing.

[0138] (1) Chemical composition analysis of MCuFe-MOF@PMMA@MXene microspheres prepared by hydrogen bond self-assembly

[0139] Figure 1 The XRD spectra of DL-MXene, MCuFe-MOF, MCuFe-MOF@PMMA and hydrogen-bonded self-assembled MCuFe-MOF@PMMA@MXene microspheres in Example 1. As can be seen from the figure, the XRD of DL-MXene has an obvious diffraction peak at about 2θ=6.25°, which is the (002) crystal plane of MXene. The interlayer spacing of MXene is calculated according to the Bragg equation. It shows that MXene has a typical layered nanosheet structure. The diffraction peaks around 18.8° and 62° correspond to MXene (004) and (006). Diffraction peaks similar to MCuFe-MOF were detected in MCuFe-MOF@PMMA, and their intensity was reduced, which may be due to the assembly of MCuFe-MOF inside PMMA microspheres. MXene self-assembled on the surface of MCuFe-MOF@PMMA through hydrogen bonds to synthesize MCuFe-MOF@PMMA@MXene microspheres, and obvious MXene diffraction peaks were detected, indicating that MXene was successfully wrapped on the surface of MCuFe-MOF@PMMA.

[0140] (2) Chemical composition analysis of MCuFe-MOF / PMMA@MXene microspheres prepared by solvothermal method

[0141] Figure 2The XRD spectra of PMMA@MXene, MCuFe-MOF and solvothermal MCuFe-MOF / PMMA@MXene microspheres in Example 2 show that in MCuFe-MOF, there are clear peaks at 30.2, 35.5, 43.3, 53.6, 57.1 and 62.7°, corresponding to CuFe 2 O 4 The diffraction peaks at 43.3, 50.7 and 74.1° correspond to the (111), (200) and (220) crystal planes of Cu. The introduction of metal elements can promote the Fe-ionization reaction in the process of photo-Fenton degradation of MB. 3+ / Fe 2+ The cycle provides electrons, thereby increasing the degradation rate.

[0142] (3) Chemical composition analysis of MCuFe-MOF / PMMA@MXene microspheres prepared by in situ growth method

[0143] Figure 3 Figure 3 shows the XRD spectra of PMMA@MXene and in-situ grown MCuFe-MOF / PMMA@MXene microspheres. It can be seen from the figure that there are obvious diffraction peaks at 6.72° and 60.85° in PMMA@MXene, corresponding to the (002) and (110) crystal planes of MXene, indicating that MXene is successfully assembled on the PMMA surface. In MCuFe-MOF / PMMA@MXene microspheres, the broad peak at about 2θ=13.1° can be attributed to the (100) crystal plane of MCuFe-MOF, CuFe 2 O 4 There are clear peaks at 30.2, 35.5, 43.3, 53.6, 57.1 and 62.7°, corresponding to the crystal planes (220), (311), (400), (422), (511) and (440), respectively (JCPDS card 77-0010). 3 After BTC reaction, it belongs to CuFe 2 O 4 The peak still exists, indicating that MCuFe-MOF is successfully assembled on the MXene@PMMA surface.

[0144] Test Example 2

[0145] Morphology of bimetallic MOF / MXene composites prepared by different methods

[0146] Figure 4The SEM images of PMMA microspheres (left) and PMMA@MXene microspheres (right) in Example 2 show that the PMMA microspheres prepared by emulsion polymerization have a regular spherical structure, and the MXene three-dimensional structure is constructed by wrapping MXene on the surface of PMMA through hydrogen bonds.

[0147] Figure 5 The SEM images of MCuFe-MOF (left) and MCuFe-MOF@PMMA microspheres (right) in Example 1, CuFe 2 O 4 It is directly prepared by hydrothermal reaction. 2 O 4 As a magnetic substrate and metal precursor, H 3 BTC and Fe 3+ and Cu 2+ Interfacial reaction occurs in the magnetic CuFe 2 O 4 MIL-100 (Fe, Cu) was generated in situ on the surface, with homologous bimetallic copper and iron elements, and MCuFe-MOF had a regular, nearly spherical morphology.

[0148] Figure 6 This is the SEM image of the MCuFe-MOF@PMMA@MXene microspheres prepared by the hydrogen bond self-assembly method in Example 1. After the MCuFe-MOF@PMMA surface is coated with MXene, the hydrogen bond self-assembled MCuFe-MOF@PMMA@MXene microspheres are obtained.

[0149] Figure 7 This is the SEM image of MCuFe-MOF / PMMA@MXene prepared by the solvothermal method in Example 2. It can be seen from the figure that MCuFe-MOF / PMMA@MXene failed to maintain a spherical three-dimensional structure during the solvothermal process and the microspheres were severely agglomerated and had insufficient dispersion.

[0150] Figure 8 This is the SEM image of the MCuFe-MOF / PMMA@MXene microspheres prepared by the in-situ growth method in Example 3. It can be seen from the figure that the MCuFe-MOF / PMMA@MXene microspheres grown by the in-situ growth method have a spherical structure similar to that of the PMMA@MXene microspheres, and the MCuFe-MOF is evenly distributed on the surface of the PMMA@MXene.

[0151] Test Example 3

[0152] Catalytic performance test of MCuFe-MOF / PMMA@MXene microspheres prepared by in situ growth method in Example 3

[0153] The surface properties are crucial to the catalytic performance of the material. In order to understand the porous structure of MCuFe-MOF / PMMA@MXene microspheres, N 2 Adsorption-desorption test.

[0154] Fig. 9 N of MCuFe-MOF / PMMA@MXene microspheres prepared by in situ growth method 2 Adsorption-desorption curve, Fig.10 The pore size distribution curve of MCuFe-MOF / PMMA@MXene microspheres prepared by in-situ growth method. According to the latest IUPAC classification, MCuFe-MOF / PMMA@MXene microspheres prepared by in-situ growth method have H4 type hysteresis loop and I type isotherm, and the specific surface area is 288.853m 2 / g, and the average pore size is 2.312nm. The large specific surface area is conducive to the adsorption of substrates on the catalyst surface, and the presence of mesoporous structure can promote the material transfer between oxidants and pollutants.

[0155] Test Example 4

[0156] Photo-Fenton degradation performance test of MCuFe-MOF / PMMA@MXene microspheres prepared by the in situ growth method in Example 3.

[0157] (1) Photo-Fenton degradation of methylene blue using different catalysts

[0158] The catalysts are MCuFe-MOF@PMMA, MCuFe-MOF / PMMA@MXene microspheres and MCuFe-MOF.

[0159] Add 100 mL of MB solution with an initial concentration of 4 g / L and pH = 3 and 0.1 g of catalyst to the conical flask, seal the conical flask with plastic wrap, and place it in a 47°C constant temperature oscillator for 30 minutes for adsorption-desorption. After the adsorption-desorption is completed, take out the conical flask, take a certain amount of the mixed solution and filter it with a filter membrane to obtain a clear solution. Test the absorbance of the filtered clear solution at a wavelength of 664 nm and record the data. Then add H 2 O 2 aqueous solution, and the resulting mixed solution (H 2 O 2 The concentration was 70 mM) and the degradation reaction was carried out under a xenon lamp. Every 10 minutes, about 8 mL of the mixed solution was taken out with a syringe, filtered through a 0.22 μm filter head, and then 0.3 mL of tert-butyl alcohol was added to quench the free radicals and terminate the Fenton reaction. The instantaneous concentration of MB at a wavelength of 664 nm was tested by UV-visible spectrophotometry. The calculation formula of MB removal rate ω is shown in Formula 1:

[0160]

[0161] Where, ω is the removal rate of MB; C 0 is the initial concentration of MB in the solution, in mg / L; C is the instantaneous concentration of MB in the solution during degradation, in mg / L.

[0162] Fig.11 The performance of hydrogen-bonded self-assembled MCuFe-MOF@PMMA@MXene microspheres as a photo-Fenton catalyst for MB degradation (70 mM H 2 O 2 , pH = 3, 100mL4g / LMB, catalyst dosage 0.1g / L, 47℃), it can be seen that the performance of MCuFe-MOF@PMMA microspheres in photo-Fenton degradation of MB is significantly lower than that of MCuFe-MOF. This is because MCuFe-MOF is wrapped by PMMA, H 2 O 2 It cannot be excited by the Cu and Fe active centers of MCuFe-MOF. After assembling the DL-MXene shell on the surface of MCuFe-MOF@PMMA, the adsorption performance is significantly improved, which may be due to the large specific surface area and rich functional groups of MXene. At the same time, the efficiency of MB degradation by MCuFe-MOF@PMMA@MXene microspheres is slightly improved, which is attributed to the good conductivity of MXene, which can be used as a co-catalyst to improve the transfer efficiency of photogenerated electrons.

[0163] Fig.12 Photo-Fenton degradation performance of MB in MCuFe-MOF / PMMA@MXene microspheres prepared by in situ growth method (70 mM H 2 O 2 , pH = 3, 100mL4g / LMB, catalyst dosage of 0.1g / L, 47℃), it can be seen that the degradation rates of MB by MCuFe-MOF and MXene@PMMA are 83.5% and 10% respectively, indicating that the active center of degradation is mainly MCuFe-MOF. The catalytic performance of MCuFe-MOF / PMMA@MXene microspheres is improved to 91.9%, indicating that MXene microspheres as co-catalysts construct Schottky junctions with MCuFe-MOF, synergistically improving the catalytic performance of the catalyst.

[0164] (2)H 2 O 2 Effect of dosage on photo-Fenton degradation of methylene blue by in situ growth MCuFe-MOF / PMMA@MXene microspheres

[0165] H 2 O 2 The amount of H affects the catalytic activity of MCuFe-MOF / PMMA@MXene microspheres.2 O 2 The concentration of is closely related to the generation of OH. As shown in Equations 2 and 3, the excess H 2 O 2 Can react with OH to generate HO with lower redox potential 2 ·, resulting in the removal of ·OH.

[0166] H 2 O 2 +·OH→H 2 O+HO 2 (Formula 2)

[0167] HO 2 ·+·OH→H 2 O+O 2 (Formula 3).

[0168] H 2 O 2 The difference between the experimental operation of photo-Fenton degradation of methylene blue and (2) photo-Fenton degradation of methylene blue with different catalysts is that: 2 O 2 The concentrations were 30mM, 50mM, 70mM and 90mM respectively, and the catalyst was MCuFe-MOF / PMMA@MXene microspheres.

[0169] Fig.13 H 2 O 2 The effect of the addition amount of H on the degradation of MB by in-situ growth method MCuFe-MOF / PMMA@MXene microspheres (pH = 3, MB concentration of 4 g / L, catalyst dosage of 0.1 g / L, 47 ° C) shows that when H 2 O 2 When the dosage was 30 mM, the MB degradation rate was only 68.3%, indicating that a small amount of H 2 O 2 It is not enough to support the photo-Fenton reaction to produce enough OH to completely oxidize and degrade MB. 2 O 2 When the dosage increased to 70 mM, the degradation rate gradually increased to 91.9%. 2 O 2 When the concentration further increased to 90 mM, the degradation rate of MB slowed down and the degradation rate decreased. 2 O 2 The dosage is 70mM.

[0170] Test Example 5

[0171] Study on the photo-Fenton degradation mechanism of MB by in-situ growth MCuFe-MOF / PMMA@MXene microspheres: Batch experiment, photocatalyst (in-situ growth MCuFe-MOF / PMMA@MXene), light (with or without xenon lamp irradiation), Fenton (H 2 O 2 ), and measure its MB degradation rate.

[0172] Photo-Fenton degradation of methylene blue: Add 100 mL of MB aqueous solution with initial concentrations of 4 g / L, 1 g / L, and 50 mg / L at pH = 3 and 0.1 g of catalyst to a conical flask, seal the conical flask with plastic wrap, and place it in a constant temperature oscillator for 30 minutes. After adsorption-desorption is completed, take out the conical flask, take a certain amount of the mixed solution and filter it with a filter membrane to obtain a clear solution, measure the absorbance of the filtered clear solution, and record the data. Then add 715 μL of 9.79 MH 2 O 2 The MB-H 2 O 2 The mixed solution was subjected to degradation reaction under a xenon lamp. Every 10 minutes, about 8 mL of the mixed solution was taken out with a syringe, filtered through a 0.22 μm filter head, and then 0.3 mL of tert-butyl alcohol was added to quench the free radicals and terminate the Fenton reaction. The instantaneous MB concentration in the solution was studied by UV-visible spectrophotometry at a wavelength of 664 nm. 2 O 2 H in the mixed solution 2 O 2 The concentration is 70mM.

[0173] Fig.14 The degradation curves of MB under different conditions show that when no catalyst is added (in H 2 O 2 + light condition), the degradation rate of MB was low, and the degradation rate within 60 min was 3.6%. When adding catalyst and introducing light, the degradation rate of MB was slightly improved, and the degradation rate within 60 min was 12.7%. 2 O 2 After the photo-Fenton reaction was started, the degradation rate of MB was significantly improved, and the degradation rate of 4 g / L MB reached 91.9% within 60 min. In order to explore the effect of light on the reaction, the MCuFe-MOF / PMMA@MXene microsphere composite material was placed in a dark environment and H 2 O 2The Fenton reaction was started, and the results showed that the degradation rate was 68.2% within 60 minutes. The degradation rate was significantly lower than that of the photo-Fenton reaction, but significantly higher than that of photocatalysis. This shows that the degradation of MB by the MCuFe-MOF / PMMA@MXene microsphere heterogeneous photo-Fenton system is not a simple addition of photocatalysis and Fenton reaction, but the two complement each other and synergistically improve the degradation rate of MB.

[0174] Fig.15 This is the degradation curve of low concentration (50 mg / L) MB by in-situ growth method MCuFe-MOF / PMMA@MXene in Example 3. The degradation rate of 50 mg / L MB reached 98.1% within 60 min (under H 2 O 2 +lighting conditions).

[0175] Fig.16 This is the degradation curve of low concentration (1 g / L) MB by in situ growth method MCuFe-MOF / PMMA@MXene in Example 3. The degradation rate of 1 g / L MB reached 96.7% within 60 min (under H 2 O 2 +lighting conditions).

[0176] In summary, the possible mechanism of MB degradation by photo-Fenton of MCuFe-MOF / PMMA@MXene microspheres prepared by in situ growth method is: MB is first adsorbed on the surface of the catalyst due to the large specific surface area and developed pore structure of MCuFe-MOF; then, Fe 2+ and Cu 2+ Catalytic H 2 O 2 The generated OH is oxidized to Fe 3+ (Fe 3+ It can also catalyze H 2 O 2 Generate O 2- , which is reduced to Fe 2+ , but this reaction is extremely slow). Finally, MB is oxidatively degraded on the surface of MCuFe-MOF / PMMA@MXene microspheres.

[0177] There are two active centers of Fe and Cu in MCuFe-MOF. + Not only does it participate in the Fenton-like reaction to activate H 2 O 2 , and Fe 3+ Reduction to Fe 2+ Under light conditions, the structural unit composed of Fe-O clusters has the properties of metal oxide semiconductors, mainly composed of O 2pThe electrons in the valence band of the orbital are excited by the energy of photons and jump to the conduction band, generating photogenerated electrons (e - ) and photogenerated holes (h + ), the electrons are from O 2- Fe 3+ Transfer occurs (Fe 3+ →Fe 2+ ), can also be conducted through MXene to inhibit carrier recombination. At the same time, CuFe 2 O 4 The heterojunction formed with MCuFe-MOF greatly improves the e - and h + The separation efficiency of Fe 2+ regeneration; due to h + It has high oxidizability, so it can directly degrade MB and improve the photo-Fenton efficiency.

[0178] In addition, visible light can directly decompose H 2 O 2 Generate ·OH. ·OH attacks MB and destroys its structure, thus achieving the purpose of degradation and decolorization.

[0179] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bimetallic MOF / MXene composite material, comprising MXene microspheres and MCuFe-MOF, wherein the MXene microspheres are located on the surface of the MCuFe-MOF, or the MCuFe-MOF is located on the surface of the MXene microspheres; the MXene microspheres comprise PMMA microspheres and a MXene shell located on the surface of the PMMA microspheres; the MCuFe-MOF has a 3D core-shell structure, wherein the core is CuFe2O4 and the shell is MIL-100 (Fe, Cu) material.

2. The method for preparing the bimetallic MOF / MXene composite material according to claim 1 is prepared by hydrogen bond self-assembly method, comprising the following steps: The initiator, polymethylpyrrolidone, MCuFe-MOF, methyl methacrylate and alcohol solvent are mixed to carry out polymerization reaction to obtain MCuFe-MOF@PMMA microspheres; The MCuFe-MOF@PMMA microspheres, a single layer of MXene and water are mixed, MXene is self-assembled on the surface of MCuFe-MOF@PMMA through hydrogen bonds, and MXene is wrapped on the surface of MCuFe-MOF@PMMA to obtain the bimetallic MOF / MXene composite material.

3. The preparation method according to claim 2, characterized in that: The preparation method of the MCuFe-MOF comprises the following steps: CuFe2O4 nanoparticles, trimesic acid and ethanol aqueous solution were mixed and subjected to a solvothermal reaction to obtain MCuFe-MOF.

4. The method for preparing the bimetallic MOF / MXene composite material according to claim 1 is prepared by a solvothermal method, comprising the following steps: PMMA@MXene microspheres, CuFe2O4 nanoparticles, trimesic acid and an alcohol aqueous solution are mixed and subjected to a solvothermal reaction to obtain the bimetallic MOF / MXene composite material.

5. The method for preparing the bimetallic MOF / MXene composite material according to claim 1, prepared by an in-situ growth method, comprises the following steps: PMMA@MXene microspheres, CuFe2O4 nanoparticles, trimesic acid and lower alcohols are mixed, and MCuFe-MOF is in situ grown on the surface of PMMA@MXene to obtain the bimetallic MOF / MXene composite material.

6. The preparation method according to claim 4 or 5, characterized in that: The preparation method of the PMMA@MXene microspheres comprises the following steps: The aqueous dispersion of PMMA microspheres and Ti3C2T x The colloidal solutions were mixed and surface hydrogen bonding self-assembled to obtain PMMA@MXene microspheres.

7. Use of the bimetallic MOF / MXene composite material according to claim 1 or the bimetallic MOF / MXene composite material prepared by the preparation method according to any one of claims 2 to 6 as a catalyst in the degradation of organic pollutants.

8. The use according to claim 7, characterized in that: The method for degrading organic pollutants includes degrading organic pollutants by photo-Fenton reaction.

9. The use according to claim 7 or 8, characterized in that: The organic contaminants include methylene blue.

10. The use according to claim 7 or 8, characterized in that: The mass ratio of the bimetallic MOF / MXene composite material to the organic pollutant is 1:0.05-4.

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