CQDs (at) HOF-101 composite microcrystal and preparation method and application thereof

Abstract

The embodiment of the invention discloses a CQDs-coated HOF-101 composite microcrystal as well as a preparation method and application thereof, relates to the technical field of photocatalytic materials, and aims to solve the technical problem that an existing photocatalytic material is relatively low in light utilization rate. The preparation method of the CQDs (at) HOF-101 composite microcrystal comprises the following steps: uniformly dissolving HOF-101 micromolecule 1, 3, 6, 8-tetra (4-carboxybenzene) pyrene in a polar aprotic solvent, filling the solution and carbon dots into a small glass bottle through an organic filter membrane, uncapping the small bottle, placing the small bottle into a beaker filled with an alcohol solvent, and after the alcohol solvent enters the organic solvent, adding the organic filter membrane into the beaker, so as to obtain the CQDs (at) HOF-101 composite microcrystal, namely the CQDs (at) HOF-101 micromolecule 1, 3, 6, 8-tetra (4-carboxybenzene) pyrene. And after crystals grow out, centrifuging to obtain precipitates, and washing the precipitates to obtain the CQDs (at) HOF-101 crystals.

Description

Technical Field

[0001] The present application relates to the technical field of photocatalytic materials, and in particular to CQDs@HOF-101 composite microcrystals and their preparation methods and applications. Background Art

[0002] As human civilization rapidly develops, energy consumption is increasing. The overuse of fossil fuels has not only triggered an energy crisis but also led to a series of environmental problems, including an intensified greenhouse effect, air pollution, and water pollution. These issues pose a serious threat to ecological balance and sustainable human development. Therefore, exploring energy-saving and environmentally friendly energy conversion strategies has become a key path to resolving the energy crisis and achieving green development, and is a top priority for humanity's future. Among numerous renewable energy projects, photocatalytic technology stands out as one of the most promising research areas due to its unique ability to directly harness solar energy to drive chemical reactions, converting solar energy into chemical energy or degrading pollutants.

[0003] With the continuous advancement of photocatalytic research, researchers have devoted considerable effort to developing a wide variety of photocatalytic materials. Graphitic carbon nitride (g-C3N4), a typical non-metallic photocatalytic material, has attracted considerable attention in areas such as photocatalytic water splitting to produce hydrogen and organic pollutant degradation due to its facile synthesis, excellent chemical stability, and suitable band structure. Titanium dioxide (TiO2), with its excellent photocatalytic activity, high chemical stability, low cost, and non-toxicity, has long been a "star material" in the photocatalytic field, widely used in practical applications such as air purification and self-cleaning coatings. Cadmium sulfide (CdS) has a narrow bandgap and can effectively absorb visible light, exhibiting advantages in visible-light-driven photocatalytic reactions. Metal-organic frameworks (MOFs), with their highly tunable pore structures and abundant active sites, provide a unique microenvironment for photocatalytic reactions, showing great potential for photocatalytic hydrogen production and carbon dioxide reduction.

[0004] However, despite their respective advantages, these photocatalytic materials still face many bottlenecks in practical applications. Photogenerated electron-hole pairs migrate slowly within the material, just like a vehicle struggling to move forward on a crowded road, making it difficult for them to quickly reach the reaction site to participate in the catalytic reaction; and the rapid recombination of photogenerated carriers is like the strong "attraction" between electrons and holes, causing them to recombine before they take effect, resulting in a significant reduction in photocatalytic efficiency. In addition, the stability of materials during long-term illumination and chemical reactions cannot be ignored. After multiple cycles of use, many photocatalytic materials will experience a reduction in active sites and structural collapse. This makes the construction of photocatalytic materials with both stable durability and efficient photocatalytic activity a difficult problem that researchers urgently need to overcome. Only by overcoming these challenges can photocatalytic technology truly achieve large-scale industrial applications and provide practical and effective solutions to energy and environmental problems. Summary of the Invention

[0005] The main purpose of this application is to provide CQDs@HOF-101 composite microcrystals and their preparation method and application, aiming to solve the technical problem of low light utilization efficiency of existing photocatalytic materials.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows: In a first aspect, the present invention provides a method for preparing CQDs@HOF-101 composite microcrystals, comprising the following steps: After the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent, it was placed into a glass vial together with carbon dots through an organic filter membrane. The vial was opened and placed in a beaker filled with an alcohol solvent. After the alcohol solvent entered the organic solvent and crystals grew, centrifugation was performed to obtain a precipitate. The precipitate was washed to obtain CQDs@HOF-101 crystals.

[0007] As some optional embodiments of the present application, before placing the vial with the cap opened in a beaker containing an alcohol solvent, the method further comprises: ultrasonically mixing the vial for 10 minutes to achieve uniform mixing; The step of opening the vial and placing it in a beaker filled with an alcohol solvent, and waiting for the alcohol solvent to enter the organic solvent refers to storing the vial with the vial opened, placing the vial in a beaker filled with an alcohol solvent, the alcohol solvent not covering the vial, sealing the beaker, and letting it stand for 24 hours, and waiting for the alcohol solvent to enter the organic solvent.

[0008] As some optional embodiments of the present application, the solid-liquid ratio of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene to the polar aprotic solvent is: 20 mg-30 mg: 2 ml-3 ml.

[0009] As some optional embodiments of the present application, the polar aprotic solvent includes any one of N,N-dimethylformamide and dimethyl sulfoxide.

[0010] As some optional embodiments of the present application, the pore size of the organic filter membrane is 0.22 μm.

[0011] As some optional embodiments of the present application, the alcohol solvent includes any one of methanol and ethanol; 10ml-15ml of alcohol solvent is used for every 20mg-30mg of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; When washing the precipitate to obtain HOF-101 crystals, the washing solvents used were methanol and acetone, and the washing times were 3 times each.

[0012] As some optional embodiments of the present application, the loading amount of the carbon dots is 0.5 wt %.

[0013] As some optional embodiments of the present application, the parameters of the centrifugal treatment are 10000 rpm and 10 min.

[0014] In a second aspect, the embodiments of the present application further provide a CQDs@HOF-101 composite microcrystal, which is prepared by the method described above.

[0015] In a third aspect, an embodiment of the present application further provides an application of CQDs@HOF-101 composite microcrystals, wherein the CQDs@HOF-101 composite microcrystals are used to prepare photocatalytic materials.

[0016] Compared with the prior art, the present invention has the following advantages: At a time when photocatalytic material research and development is constantly pursuing breakthroughs, the preparation method of CQDs@HOF-101 composite microcrystals described in this application demonstrates unique innovation and application value. This preparation process cleverly combines hydrogen-bonded organic framework (HOF) materials with carbon dots (CQDs) through carefully designed steps. First, the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene is used as a building block, and a polar aprotic solvent provides a suitable self-assembly environment. The two interact, driving the self-assembly process through intermolecular hydrogen bonds, like building "Lego blocks" at the molecular level, gradually forming HOF-101 crystals with a regular pore structure.

[0017] On this basis, during the HOF-101 crystal growth process, the carbon dots are evenly dispersed in the system, allowing them to precisely embed into the pores or lattice gaps of the HOF-101 crystal, avoiding the agglomeration or uneven distribution problems that may occur with traditional loading methods. After the crystals are fully grown, the precipitate is separated by centrifugation and then washed multiple times to remove impurities and excess solvent that did not participate in the reaction, ultimately obtaining pure CQDs@HOF-101 crystals.

[0018] From the perspective of raw material selection, this preparation method offers significant advantages in environmental protection and resource utilization. The use of cellulose, a naturally derived raw material with excellent biocompatibility, as a precursor for carbon dots not only leverages cellulose's widespread and renewable resources but also achieves high-value utilization of biomass. Transforming common biomass materials into carbon dots with specialized functions not only reduces reliance on non-renewable resources but also opens up a new path for biomass resource utilization, aligning with the concept of sustainable development.

[0019] In terms of performance enhancement, the CQDs@HOF-101 composite material exhibits significant advantages. On the one hand, the introduction of carbon dots effectively enhances the intrinsic photogenerated electron transport efficiency of the HOF material. The unique conjugated structure and excellent conductivity of the carbon dots act as a "highway" for photogenerated electrons, significantly shortening the electron migration path and reducing the recombination probability of photogenerated electron-hole pairs. On the other hand, the porous structure and abundant active sites of the HOF-101 crystals provide a broad reaction interface and ample adsorption space for the photocatalytic reaction. The synergistic effect of these two factors endows the composite material with excellent electron transport capacity and good photocatalytic hydrogen evolution performance.

[0020] Considering its potential applications, this preparation method is simple and easy, requires mild preparation conditions, and does not require complex equipment or harsh reaction conditions, making it suitable for large-scale industrial production. The CQDs@HOF-101 composite material demonstrates potential in photocatalytic hydrogen evolution, potentially providing a new technological solution to addressing the energy crisis. Its excellent biocompatibility also lays the foundation for its application in biomedical photocatalysis, such as photocatalytic antibacterial and controlled drug release, demonstrating broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a powder X-ray diffraction analysis result diagram of the CQDs@HOF-101 composite microcrystals involved in the examples of this application; Figure 2 This is a transmission electron microscopy analysis result of the CQDs@HOF-101 composite microcrystals involved in the examples of this application; Figure 3 This is a graph showing the nitrogen adsorption analysis results of the CQDs@HOF-101 composite microcrystals involved in the examples of this application; Figure 4 This is a photocurrent test result diagram of the CQDs@HOF-101 composite microcrystals involved in the examples of this application; Figure 5 This is a graph showing the electrochemical impedance spectroscopy test results of the CQDs@HOF-101 composite microcrystals involved in the examples of this application; Figure 6 This is a graph showing the hydrogen evolution performance test results of the CQDs@HOF-101 composite microcrystals involved in the examples of this application. DETAILED DESCRIPTION

[0022] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] At the forefront of materials science, hydrogen-bonded organic frameworks (HOFs) have become a research hotspot due to their unique construction method and potential applications. These materials form porous networks through the self-assembly of small organic molecular building blocks. Their appeal lies in the ability to precisely control the type and structure of the functional groups within the building blocks, enabling customized design of the pore structure and functionality of the HOF material. When HOFs are constructed using building blocks containing large π-conjugated structures, a shape-matched π-π stacking strategy, like a precise puzzle of intermolecular structures, significantly enhances pore stability, maintaining structural integrity even in complex environments. Furthermore, the intramolecular DA (donor-acceptor) structure and proton transport channels collaborate to create an ideal platform for efficient HER (hydrogen evolution reaction), bringing hope to the development of clean energy. However, HOFs face numerous challenges in practical applications. The rapid recombination of photogenerated charge carriers presents a significant roadblock in photocatalysis, resulting in consistently low visible light utilization. Furthermore, the material's inherent instability limits its application in a wider range of scenarios.

[0024] As an emerging member of the carbon-based zero-dimensional nanomaterial family, carbon dots (CDs) have rapidly emerged as a promising candidate for semiconductor materials due to their low cost, non-toxicity, environmental friendliness, and simple synthesis process. Their excellent photostability and electrical conductivity make them highly promising candidates for semiconductor materials. Studies have confirmed that CDs have adjustable energy level configurations, like sophisticated molecular circuits that can be optimized according to different needs; their unique conjugated structure gives them special optical and electrical properties. However, like the two sides of a coin, carbon dots themselves have obvious shortcomings: as photocatalysts, their photocatalytic efficiency cannot meet the needs of practical applications, and insufficient solar energy utilization seriously restricts their effectiveness. The existence of photobleaching greatly reduces their stability under long-term light exposure.

[0025] It is worth noting that there are currently no reports on the application of CDs / HOF composite materials in the field of photocatalysis. The solution processing method based on small molecules of HOF materials provides a new idea for breaking through the bottleneck of existing material applications. This method can achieve in-situ coating of carbon dots. This process is not only a simple combination of two materials, but also an innovative practice in the utilization of biomass resources. The introduction of carbon dots can effectively improve the intrinsic photogenerated electron transmission efficiency of HOF materials. The synergistic effect of the two is expected to construct a HER composite material with excellent performance. This preparation method does not require complex equipment and cumbersome processes. It is simple, easy and cost-controlled. It shows broad application prospects in the field of photocatalysis in the future and may become a key breakthrough in promoting the innovation of clean energy technology.

[0026] Based on the above content, this application provides the following technical solutions: A method for preparing CQDs@HOF-101 composite microcrystals comprises the following steps: After the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent, it was placed into a glass vial together with carbon dots through an organic filter membrane. The vial was opened and placed in a beaker filled with an alcohol solvent. After the alcohol solvent entered the organic solvent and crystals grew, centrifugation was performed to obtain a precipitate. The precipitate was washed to obtain CQDs@HOF-101 crystals.

[0027] Specifically, before placing the vial with the cap opened in a beaker containing an alcohol solvent, the method further comprises: ultrasonically mixing the vial for 10 minutes to uniformly mix the vial; The step of opening the vial and placing it in a beaker filled with an alcohol solvent, and waiting for the alcohol solvent to enter the organic solvent refers to storing the vial with the vial opened, placing the vial in a beaker filled with an alcohol solvent, the alcohol solvent not covering the vial, sealing the beaker, and letting it stand for 24 hours, and waiting for the alcohol solvent to enter the organic solvent.

[0028] More specifically, the material-liquid ratio of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene to the polar aprotic solvent is: 20 mg-30 mg: 2 ml-3 ml; preferably 20 mg, 2 ml, so as to reduce the amount of organic solvent while satisfying the condition of complete dissolution as much as possible.

[0029] More specifically, the polar aprotic solvent includes any one of N,N-dimethylformamide and dimethyl sulfoxide to destroy hydrogen bonds and dissolve HOF-101 small molecules.

[0030] More specifically, the pore size of the organic filter membrane is 0.22 μm to filter out most insoluble impurities.

[0031] More specifically, the alcohol solvent includes any one of methanol and ethanol; 10ml-15ml of the alcohol solvent is used for every 20mg-30mg of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; when washing the precipitate to obtain HOF-101 crystals, the washing solvents used are methanol and acetone, and the number of washes is 3 times each; it should be noted that the alcohol reagent corresponding system is a poor solvent and can effectively precipitate HOF crystals. Methanol and acetone are used as washing reagents to wash away the organic solvent (DMF, also known as N,N-dimethylformamide or DMSO, also known as dimethyl sulfoxide) in the pores. Acetone has a low boiling point and is easy to remove.

[0032] Specifically, the loading amount of the carbon dots is 0.5wt%, and the material has the best hydrogen evolution performance at this loading amount. Too much loading will destroy the crystal structure, and too little loading will have a low hydrogen evolution enhancement effect. The centrifugal treatment parameters are 10,000 rpm and 10 min, which can completely centrifuge the precipitate.

[0033] In a second aspect, the embodiments of the present application further provide a CQDs@HOF-101 composite microcrystal, which is prepared by the method described above.

[0034] In a third aspect, an embodiment of the present application further provides an application of CQDs@HOF-101 composite microcrystals, wherein the CQDs@HOF-101 composite microcrystals are used to prepare photocatalytic materials.

[0035] To facilitate those skilled in the art to understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments: The carbon dots described in the following examples were prepared by the following steps: 2.00 g of microcrystalline cellulose was placed in 60.00 mL of deionized water and magnetically stirred at 500 rpm for 10 minutes. The suspension was then transferred to a polytetrafluoroethylene-lined hydrothermal reactor. The reactor was then placed in an electrically heated constant-temperature forced-air drying oven and reacted at 200°C for 12 hours. After cooling to room temperature, the reaction solution was centrifuged at 10,000 rpm for 10 minutes. The centrifuged solution was passed through a 0.22 μm aqueous pinhole filter membrane and placed in a dialysis bag with a 1000 Da molecular weight cutoff for 48 hours. Finally, the solution was freeze-dried to obtain cellulose carbon dots (CQDs).

[0036] Example 1: Raw materials: microcrystalline cellulose, 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; Solvents: DMF and methanol; Reaction device: oven; The cellulose carbon dot / hydrogen bond organic framework composite material was prepared from the following raw materials: 2 g of microcrystalline cellulose and 20 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene.

[0037] The solvents were prepared by the following volumes: DMF was 2 ml, methanol was 15 ml; After the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent, it was poured into a 20ml glass vial through an organic filter membrane. At the same time, carbon dots were added to the glass vial and ultrasonicated for 10 minutes to mix them evenly. The vial was placed in a beaker filled with an alcohol solvent, the beaker was sealed and allowed to stand for 24 hours to allow the alcohol solvent to enter the organic solvent. After crystals grew, they were centrifuged to obtain a precipitate, which was washed to obtain CQDs@HOF-101 crystals.

[0038] Specifically, the carbon dot loading is 0.5 wt %. The alcohol solvent includes either methanol or ethanol. The precipitate is washed three times with methanol and three times with acetone, and finally dried in a vacuum oven at 60°C for 24 hours. The centrifugation parameters are 10,000 rpm for 10 minutes.

[0039] Example 2: Raw materials: microcrystalline cellulose, 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; Solvents: DMSO and ethanol; Reaction device: oven; The cellulose carbon dot / hydrogen bond organic framework composite material was prepared from the following raw materials: 2 g of microcrystalline cellulose and 25 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene.

[0040] The solvents were prepared by the following volumes: DMSO was 2.5 ml, ethanol was 30 ml; After the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent, it was poured into a 20ml glass vial through an organic filter membrane. At the same time, carbon dots were added to the glass vial and ultrasonicated for 10 minutes to mix them evenly. The vial was placed in a beaker filled with an alcohol solvent, the beaker was sealed and allowed to stand for 24 hours to allow the alcohol solvent to enter the organic solvent. After crystals grew, they were centrifuged to obtain a precipitate, which was washed to obtain CQDs@HOF-101 crystals.

[0041] Specifically, the carbon dot loading is 0.5 wt %. The alcohol solvent includes either methanol or ethanol. The precipitate is washed with methanol and acetone three times each, and finally dried in a vacuum oven at 60° C. for 24 hours. The centrifugation parameters are 10,000 rpm for 10 minutes.

[0042] Example 3: Raw materials: microcrystalline cellulose, 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; Solvents: DMSO and ethanol; Reaction device: oven; The cellulose carbon dot / hydrogen bond organic framework composite material was prepared from the following raw materials: 1.5 g of microcrystalline cellulose and 25 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene.

[0043] The solvents were prepared by the following volumes: DMSO was 2.5 ml, ethanol was 30 ml; The HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent and then loaded into a 20ml glass vial through an organic filter membrane. At the same time, carbon dots were added to the glass vial and ultrasonicated for 10 minutes to uniformly mix them. The vial was placed in a beaker filled with an alcohol solvent and the beaker was sealed. After crystals grew, centrifugation was performed to obtain a precipitate, which was washed to obtain CQDs@HOF-101 crystals.

[0044] Specifically, the carbon dot loading is 0.5 wt %. The alcohol solvent includes either methanol or ethanol. When washing the precipitate to obtain HOF-101 crystals, the washing solvents used are methanol and acetone, and the number of washes is three for each. The centrifugation parameters are 10,000 rpm and 10 min.

[0045] Experimental Example 1: The following structural analysis was performed on the CQDs@HOF-101 crystal prepared in Example 1: 1) Powder X-ray diffraction: After the CQDs@HOF-101 crystals were dried into powder, the crystals were qualitatively analyzed by X-ray diffraction.

[0046] The results are as follows Figure 1 As shown: the composite has a certain crystal structure, and the diffraction intensity becomes lower after loading.

[0047] 2) Transmission electron microscopy: CQDs@HOF-101 crystals were uniformly dispersed in ethanol by ultrasonication. A drop of the dispersion was added to a copper grid and allowed to dry naturally at room temperature.

[0048] The results are as follows Figure 2 As shown: It shows that the carbon dots are successfully loaded on HOF-101.

[0049] 3) Nitrogen adsorption: The CQDs@HOF-101 crystals were activated overnight on a nitrogen adsorption instrument and then subjected to nitrogen adsorption test.

[0050] The results are as follows Figure 3As shown: the nitrogen adsorption amount of HOF-101 decreased after loading carbon dots, indicating that the carbon dots were successfully embedded in the pores.

[0051] Experimental Example 2: The following performance tests were performed on the CQDs@HOF-101 crystal prepared in Example 2: 1) Photocurrent test: CQDs@HOF-101 was dispersed in ethanol, dropped onto the working electrode, illuminated with a 1W LED lamp, and the photocurrent test was performed on an electrochemical workstation.

[0052] The results are as follows Figure 4 As shown in the figure: the photocurrent response of CQDs@HOF-101 after loading carbon dots is significantly stronger than that of HOF-101, indicating that the separation and bulk transmission efficiency of photogenerated electron-hole pairs are better after loading carbon dots.

[0053] 2) Electrochemical impedance spectroscopy: CQDs@HOF-101 was dispersed in ethanol and dropped onto the working electrode, and the photocurrent was measured on an electrochemical workstation.

[0054] The results are as follows Figure 5 As shown: The electrochemical impedance of CQDs@HOF-101 after loading carbon dots is lower than that of HOF-101, indicating that the transfer rate of photogenerated electrons and holes is fast and the recombination loss is less.

[0055] 3) Hydrogen evolution performance test: Carbon dots (CQDs) and HOF-101 were added in the loading step, with the mass ratios of the two being: 0.3:100, named 0.3 CQDs@HOF-101; 0.5:100, named 0.5 CQDs@HOF-101; 0.7:100, named 0.7 CQDs@HOF-101; 1.0:100, named 1.0 CQDs@HOF-101.

[0056] The results are as follows Figure 6 As shown in the figure, the hydrogen evolution performance of HOF-101 is improved after loading carbon dots with different masses, and the hydrogen evolution performance of 0.5 CQDs@HOF-101 is the best.

[0057] In summary, the CQDs@HOF-101 crystals prepared in this application are simple to prepare under mild conditions. The use of cellulose, a naturally occurring biocompatible raw material, as a precursor for the carbon dots enables high-value utilization of biomass. This composite material exhibits excellent electron transport and photocatalytic hydrogen evolution performance, promising promising applications.

[0058] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing CQDs@HOF-101 composite microcrystals, characterized in that: The following steps are involved: After the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was uniformly dissolved in a polar aprotic solvent, it was placed into a glass vial together with carbon dots through an organic filter membrane. The vial was opened and placed in a beaker filled with an alcohol solvent. After the alcohol solvent entered the organic solvent and crystals grew, centrifugation was performed to obtain a precipitate. The precipitate was washed to obtain CQDs@HOF-101 crystals.

2. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 1, characterized in that: Before the vial is opened and placed in a beaker filled with an alcohol solvent, the method further comprises: performing ultrasonic treatment for 10 minutes to uniformly mix the vial.

3. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 2, characterized in that: The material-liquid ratio of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene to the polar aprotic solvent is: 20 mg-30 mg: 2 ml-3 ml.

4. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 2, characterized in that: The polar aprotic solvent includes any one of N,N-dimethylformamide and dimethyl sulfoxide.

5. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 2, characterized in that: The pore size of the organic filter membrane is 0.22 μm.

6. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 2, characterized in that: The alcohol solvent includes any one of methanol and ethanol; 10ml-15ml of alcohol solvent is used for every 20mg-30mg of the HOF-101 small molecule 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene; When washing the precipitate to obtain HOF-101 crystals, the washing solvents used were methanol and acetone, and the washing times were 3 times each.

7. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 1, characterized in that: The loading amount of the carbon dots is 0.5 wt %.

8. The method for preparing CQDs@HOF-101 composite microcrystals according to claim 1, characterized in that: The processing parameters of the centrifugation are 10000 rpm and 10 min.

9. A CQDs@HOF-101 composite microcrystal, characterized in that: The method is prepared by any one of claims 1 to 8.

10. An application of CQDs@HOF-101 composite microcrystals, characterized in that: The CQDs@HOF-101 composite microcrystals as described in claim 9 are used to prepare photocatalytic materials.

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