Preparation method and application of MIL-101 (Fe) cage packaged ZnO nanoparticle composite material

Abstract

The invention belongs to the technical field of new materials, and particularly relates to a preparation method and application of an MIL-101 (Fe) cage packaged ZnO nanoparticle composite material. According to the invention, a metal-organic framework (MOF) material MIL-101 (Fe) with two mesoporous cages and a microporous cage is used as a carrier, and nano particles of ZnO, which is a metal oxide, are packaged by using three cage structures in the structure of the metal-organic framework (MOF) material, so that the ZnO-coated MIL-101 (Fe) composite material prepared by enabling the ZnO nano particles to completely enter pores of the MOF material is prepared. The ZnO coated MIL-101 (Fe) is a catalytic material with efficient catalytic capability, is highly dispersed nano-scale ZnO, and can effectively exert the photocatalytic H2O2 production performance of the ZnO coated MIL-101 (Fe). Meanwhile, the preparation method disclosed by the invention is simple to operate, good in repeatability, mild in condition and environment-friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new materials, and particularly relates to a preparation method and application of a MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material. BACKGROUND

[0002] In recent years, with the increasing energy shortage and environmental pollution problems, the demand for fossil fuels is growing, so it has become an urgent scientific challenge to develop green and sustainable energy alternatives. H2O2, as a green oxidant and clean fuel, is widely used in chemical synthesis, pharmaceutical industry and water treatment industrial processes. Therefore, it is urgent to find a fast, large-scale, environmentally friendly and pollution-free method for preparing H2O2.

[0003] So far, more than 95% of H2O2 is produced in industry by anthraquinone oxidation method, and photocatalytic method is considered as the most promising green synthesis approach due to its mild reaction conditions, sustainable solar energy driving and zero carbon emission. It has become one of the important methods for preparing H2O2. Common photocatalysts are noble metals, transition metal oxides, etc. Although the catalytic performance and stability of noble metal catalysts are good, the cost of noble metals is too high, and the natural reserves are low, which is difficult to be used in large-scale actual production. Transition metal oxides are easy to obtain and cheap, but they have the disadvantages of poor catalytic efficiency and stability. ZnO has unique photoelectric structure and significant cost advantage, and its preparation method is environmentally friendly and green, so it is an important precursor for researching photocatalysts. Therefore, it has obvious advantages and great significance to prepare H2O2 catalyst by preparing a composite material based on ZnO.

[0004] MOF is a kind of framework material formed by combining metal centers and numerous organic ligands, which has the characteristics of designable pore structure size and super-high specific surface area. These characteristics provide a new idea for photocatalysis. By putting metal oxides into suitable MOF to expose more active sites, the high dispersity of ZnO nanoparticles and the particularity of pore structure can further enhance the catalytic ability of the composite material. Therefore, designing a new type of catalytic material by this method has good development prospects for synthesizing H2O2. SUMMARY

[0005] To solve the above problems, the application provides a preparation method and application of a MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material.

[0006] The technical solution adopted by the present invention is: a method for preparing a MIL-101 (Fe) cage-encapsulated ZnO nanoparticle composite material, comprising the following steps:

[0007] 1) dissolving a zinc source and urea in ultrapure water, fully dissolving and mixing to obtain a ZnO precursor solution, and storing the ZnO precursor solution at room temperature;

[0008] 2) suspending the MIL-101(Fe) powder in a hydrophobic solvent, ultrasonicating for 5-20 minutes, and vigorously stirring to mix the mixture evenly to obtain a MIL-101(Fe) suspension;

[0009] 3) Add the ZnO precursor solution dropwise to the MIL-101(Fe) suspension at room temperature with vigorous stirring and continue stirring for 2-3 hours;

[0010] 4) After filtering and removing the solvent, the ZnO precursor was microwaved for 25 minutes to gradually age and generate ZnO nanoparticles, which were further dried. The resulting powder was collected to obtain the MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material ZnO@MIL-101(Fe).

[0011] In the above preparation method, in step 1), the zinc source is zinc nitrate, and the mass ratio of the zinc source to urea is 1:1.

[0012] In the above preparation method, in step 2), the hydrophobic solvent is one or more of n-hexane, cyclohexane, ethyl acetoacetate, and ethyl acetate.

[0013] In the above preparation method, in step 2), the concentration of the MIL-101(Fe) suspension is 5 g / L in the ZnO precursor solution.

[0014] In the above preparation method, in step 3), the volume ratio of the MIL-101(Fe) suspension to the ZnO precursor is 100:1.

[0015] In the above preparation method, in step 3), the dropwise addition rate of the ZnO precursor solution is 0.001-0.01 mL·min -1 .

[0016] In the above preparation method, in step 4), the microwave temperature is 30-150°C.

[0017] The MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material prepared by the above preparation method is used as a catalyst in the catalytic production of H2O2.

[0018] The above application method is as follows: the MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material is dispersed in deionized water, placed in a sealed container, oxygen is introduced to fill the sealed container with oxygen, and irradiated with a xenon lamp to catalytically produce H2O2.

[0019] The beneficial effects of the present invention are:

[0020] 1. The ZnO@MIL-101(Fe) composite catalytic material prepared by the present invention has the following characteristics: a) MIL-101(Fe), a classic MOF, is used as a carrier for encapsulating ZnO. At the same time, its crystal structure is well preserved throughout the preparation process; b) Under the action of the hydrophobic solvent in the two-solvent method, ZnO nanoparticles are encapsulated into the interior of the three cage-shaped channels in MIL-101(Fe) instead of aggregating on the surface; c) ZnO nanoparticles grown in the MIL-101(Fe) channels do not block the channels, and the composite material still maintains good porosity.

[0021] 2. The preparation method of the present invention has low cost, simple operation, high repeatability and mild conditions.

[0022] 3. The ZnO@MIL-101(Fe) composite catalytic material prepared by the present invention can effectively solve the problems of insufficient catalytic ability, poor moisture resistance and short service life of zinc oxide in the process of catalytic production of H2O2. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 20% ZnO@MIL-101(Fe) prepared in Example 1 and the original MIL-101(Fe) are PXRD patterns.

[0024] Figure 2 77K nitrogen adsorption curves of 20% ZnO@MIL-101(Fe) prepared in Example 1 and original MIL-101(Fe).

[0025] Figure 3 This is the H2O2 yield curve of 20% ZnO@MIL-101(Fe) prepared in Example 1 and original MIL-101(Fe) and MnO2 under visible light irradiation for 0.5h. DETAILED DESCRIPTION

[0026] To clarify the purpose, technical solutions and advantages of the present invention, the following will describe the technical solutions in the embodiments of the present invention in more detail in conjunction with the preferred embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of them.

[0027] Example 1

[0028] A method for preparing a MIL-101 (Fe) cage-encapsulated ZnO nanoparticle composite material comprises the following steps:

[0029] 1) Dissolve 600 mg of zinc nitrate and 600 mg of urea in 1 mL of ultrapure water at a mass ratio of 1:1, fully dissolve and mix to obtain a ZnO precursor solution, and store the ZnO precursor solution at room temperature;

[0030] 2) The preparation method of MIL-101(Fe) is supplemented here.

[0031] 3) 100 mg of MIL-101(Fe) powder was suspended in 20 mL of n-hexane, ultrasonicated for 15-20 min, and vigorously stirred to mix uniformly to obtain a MIL-101(Fe) suspension;

[0032] 4) At room temperature and under vigorous stirring, 0.2 mL of ZnO precursor solution was added dropwise to the MIL-101(Fe) suspension obtained in step 2) at a rate of 0.005 mL min -1 , and continue stirring for 2-3 hours;

[0033] 5) After filtering out the n-hexane, the obtained solid was microwaved at 100° C. for 25 minutes to gradually age the ZnO precursor to generate ZnO nanoparticles. The solid was dried at 60° C. and the obtained powder was collected to obtain 20% ZnO@MIL-101(Fe).

[0034] Example 2

[0035] 1) Dissolve 600 mg of zinc nitrate and 600 mg of urea in 1 mL of ultrapure water at a mass ratio of 1:1, fully dissolve and mix to obtain a ZnO precursor solution, and store the ZnO precursor solution at room temperature;

[0036] 2) Suspend 100 mg of MIL-101(Fe) powder in 20 mL of n-hexane, sonicate for 15-20 minutes, and stir vigorously to mix thoroughly to obtain a MIL-101(Fe) suspension;

[0037] 3) At room temperature and under vigorous stirring, 0.1 mL of ZnO precursor solution was added dropwise to the MIL-101(Fe) suspension obtained in step 2) at a rate of 0.005 mL min -1 , and continue stirring for 2-3 hours;

[0038] 4) After filtering to remove the n-hexane, the resulting solid was microwaved at 100°C for 25 minutes to gradually age the ZnO precursor to form ZnO nanoparticles. The solid was then dried at 60°C and the resulting powder was collected to obtain 10% ZnO@MIL-101(Fe);

[0039] Figure 1 The PXRD patterns of 20% ZnO@MIL-101(Fe) and original MIL-101(Fe) prepared in Example 1 are shown. The test instrument is Advance D8 from Bruker, Germany, using a Cu target and scanning in the 2theta range of 5-40°.

[0040] Figure 2 The graph is a 77K nitrogen adsorption curve of 20% ZnO@MIL-101(Fe) and original MIL-101(Fe) prepared in Example 1. The test instrument is 3H-2000PS1 of China Best Instruments, and the test was performed at 70°C for 6 hours.

[0041] The PXRD peaks of the 20% ZnO@MIL-101(Fe) composite are not significantly different from those of the original MIL-101(Fe). The absence of diffraction peaks from the individual ZnO crystal planes in the PXRD pattern indicates that the ZnO has entered the pores of the MIL-101(Fe) composite, forming nanoscale particles that are not visible through PXRD. Furthermore, the diffraction peaks of the MIL-101(Fe) composite remain unchanged due to the introduction of ZnO, indicating that its structure remains stable throughout the preparation process.

[0042] Example 3 Catalytic H2O2 Generation Performance of ZnO@MIL-101(Fe) Composite Material

[0043] First, 5mg of 20% ZnO@MIL-101(Fe) was dispersed in 10mL of deionized water as the test solution and added to a sealed container. A large amount of oxygen was introduced into the container to ensure it filled the entire container, and the solution was treated in the dark for 30 minutes. At room temperature, the solution was illuminated using a 300W xenon lamp for two hours, with samples taken every 0.5 hours. The sample was then subjected to a colorimetric reaction using potassium iodide and potassium hydrogen phthalate, and the absorbance was measured using a UV spectrophotometer to calculate the H2O2 yield.

[0044] Experimental findings (such as Figure 3 ). The 20% ZnO@MIL-101(Fe) composite material of the present invention produced H₂O₂ at a rate of 446 μmol / L / 2h under visible light irradiation for 2h, and this efficiency was maintained for a long time. Furthermore, the 10% ZnO@MIL-101(Fe) composite prepared in Example 2 also produced 187 μmol / L / 2h of H₂O₂.

[0045] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for preparing a MIL-101 (Fe) cage-encapsulated ZnO nanoparticle composite material, characterized in that: The steps include: 1) dissolving a zinc source and urea in ultrapure water, fully dissolving and mixing to obtain a ZnO precursor solution, and storing the ZnO precursor solution at room temperature; 2) suspending the MIL-101(Fe) powder in a hydrophobic solvent, ultrasonicating for 5-20 minutes, and vigorously stirring to mix the mixture evenly to obtain a MIL-101(Fe) suspension; 3) Add the ZnO precursor solution dropwise to the MIL-101(Fe) suspension at room temperature with vigorous stirring and continue stirring for 2-3 hours; 4) After filtering and removing the solvent, the ZnO precursor was microwaved for 25 minutes to gradually age and generate ZnO nanoparticles, which were further dried. The resulting powder was collected to obtain the MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material ZnO@MIL-101(Fe).

2. The preparation method according to claim 1, characterized in that In step 1), the zinc source is zinc nitrate, and the mass ratio of the zinc source to urea is 1:

1.

3. The preparation method according to claim 1, characterized in that In step 2), the hydrophobic solvent is one or more of n-hexane, cyclohexane, ethyl acetoacetate, and ethyl acetate.

4. The preparation method according to claim 1, characterized in that In step 2), the concentration of the MIL-101(Fe) suspension is 5 g / L in the ZnO precursor solution.

5. The preparation method according to claim 1, characterized in that In step 3), the volume ratio of the MIL-101(Fe) suspension to the ZnO precursor is 100:

1.

6. The preparation method according to claim 1, characterized in that In step 3), the dropwise addition rate of the ZnO precursor solution is 0.001-0.01 mL min -1 .

7. The preparation method according to claim 1, characterized in that In step 4), the microwave temperature is 30-150°C.

8. Use of the MIL-101(Fe) cage-encapsulated ZnO nanoparticle composite material prepared by the preparation method according to any one of claims 1 to 7 as a catalyst in the catalytic production of H2O2.

9. The use according to claim 8, characterized in that The method is as follows: a MIL-101 (Fe) cage-encapsulated ZnO nanoparticle composite material is dispersed in deionized water, placed in a sealed container, oxygen is introduced to fill the sealed container with oxygen, and irradiated with a xenon lamp to catalytically produce H2O2.

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