A titanium-porous organic cage photocatalyst and its preparation method and application

Abstract

The present invention discloses a titanium-porous organic cage photocatalyst, a preparation method thereof, and an application thereof. The present invention utilizes a resorcinol cup[4]arene-based porous organic cage HPOC-401 as a raw material, and obtains a titanium-porous organic cage HPOC-401-Ti photocatalyst with highly dispersed metal sites through a post-modification metallization reaction (PSM). This invention provides a new method for preparing an inorganic-organic composite photocatalyst containing titanium. The method requires inexpensive materials, has a simple preparation process, is easy to operate, has a low reaction temperature, and the obtained product has a large specific surface area, good stability and repeatability, and has strong operability and practicality. The method has potential application value and strong practicality in the photocatalytic degradation of dye pollutants in water.

Description

Technical Field

[0001] The present invention belongs to the field of material synthesis and catalysis, and in particular relates to a non-noble metal titanium (Ti)-porous organic cage (POC) composite material, a preparation method and application thereof. Background Art

[0002] Over the past few decades, with the continued development of the printing and dyeing industry, dye wastewater has become a significant pollutant in environmental water bodies. Scientists have developed a variety of methods for removing dye contaminants from water, including chemical precipitation, electrolysis, evaporation, distillation, adsorption separation, ion exchange, solvent extraction, reverse osmosis, microfiltration, and photocatalytic degradation. Among these methods, photocatalytic degradation is a green, environmentally friendly, novel, efficient, and energy-efficient method for removing dye contaminants from dye wastewater. It can ultimately convert the remaining dye in the water into carbon dioxide, water, or other non-toxic and harmless small molecules.

[0003] Among the catalysts used in photocatalytic degradation, titanium dioxide (TiO2) semiconductor materials have attracted widespread attention due to their wide range of applications, high catalytic efficiency, low toxicity, clean and pollution-free properties, and low price. However, due to the relatively wide band gap of TiO2 semiconductors, the light they absorb is primarily concentrated in the ultraviolet range (<5% of the solar spectrum), resulting in a low utilization rate of sunlight, which greatly restricts their practical application in photocatalysis. Therefore, it is imperative to develop simple, reproducible, and low-cost synthetic methods to prepare titanium-based photocatalysts that can efficiently utilize sunlight. Summary of the Invention

[0004] To address these technical issues, the present invention provides a method for preparing a highly dispersed titanium-porous organic cage photocatalyst using porous organic cages under simple, mild conditions. This method utilizes a post-modification metallization synthesis method to prepare the titanium-porous organic cage photocatalyst, resulting in a simple process, mild reaction, and excellent repeatability and controllability.

[0005] In order to achieve the above-mentioned object of the invention, the specific technical solutions of the present invention are as follows:

[0006] The present invention provides a composite material (abbreviated as HPOC-401-Ti), which comprises a porous organic cage compound and metallic titanium supported on the porous organic cage compound.

[0007] According to an embodiment of the present invention, in the composite material, the porous organic cage compound is used as a ligand, and metallic titanium is used as an active component. 4+ Chelated on the porous organic cage compound to form a complex. Preferably, Ti 4+Chelates on porous organic cage compounds to form complexes.

[0008] Preferably, the composite material has Figure 15 The molecular structure is shown.

[0009] According to an embodiment of the present invention, in the composite material, the mass percentage of Ti is 5-10%, exemplified by 5%, 8.63%, and 10%.

[0010] According to an embodiment of the present invention, the composite material has substantially Figure 17 The UV-visible diffuse reflectance spectrum (UV-vis) shown in FIG. 1 shows that the UV absorption edge is located at 872 nm. According to an embodiment of the present invention, the composite material is a red powder sample with a rough surface.

[0011] According to an embodiment of the present invention, the BET surface area of ​​the composite material is 976-977 m 2 g -1 , for example 976.5m 2 g -1 .

[0012] According to an embodiment of the present invention, the porous organic cage compound (abbreviated as HPOC-401), (C 384 H 408 N 48 O 72 ), having a structure as shown in Formula I:

[0013]

[0014] According to an embodiment of the present invention, the HPOC-401 is obtained by reacting tetraaldehyde resorcinol calix[4]arene (C4RACHO) and p-dibenzoic acid dihydrazide (TPHA).

[0015] Preferably, the molar ratio of tetraaldehyde resorcinol calix[4]arene (C4RACHO) to 4-dibenzoyl dihydrazine (TPHA) is 1:(1-3), exemplified by 1:1, 1:2, and 1:3.

[0016] Preferably, the reaction temperature is 80-120° C., for example, 100° C.; and the reaction time is 6-20 h, for example, 12 h.

[0017] Preferably, the reaction is carried out in an organic solvent. For example, the solvent may be N,N-dimethylformamide (DMF).

[0018] Preferably, the preparation method of HPOC-401 further comprises sonicating the reaction mixture to dissolve the solid raw materials before the heating reaction. Preferably, the sonication time can be 10 to 30 minutes, exemplarily about 20 minutes.

[0019] Preferably, the preparation method of HPOC-401 further comprises: collecting the HPOC-401 compound from the reaction solution after the reaction is completed.

[0020] Preferably, the HPOC-401 preparation method may further include evaporating the reaction solution obtained after the reaction at a constant temperature to obtain porous organic cage HPOC-401 crystals. For example, the evaporation temperature is room temperature; in another example, the evaporation time is 6-20 hours, for example, 12 hours.

[0021] Preferably, the preparation method further comprises purifying the product obtained after evaporation and crystallization, for example, by filtering, washing with methanol, exchanging methanol several times, and drying to obtain yellow powdery HPOC-401 crystals from which the guest solvent molecules have been removed.

[0022] For example, the drying method may be vacuum drying. Preferably, the drying temperature may be 60-100° C., exemplarily 100° C.; and the drying time may be 6-20 hours, for example 12 hours.

[0023] According to an embodiment of the present invention, the porous organic cage HPOC-401 crystal has a symmetry center, a space group of Pnnn, and a unit cell parameter of α=β=γ=90°.

[0024] According to an embodiment of the present invention, the porous organic cage HPOC-401 crystal is an octahedral organic cage assembled from six tetraaldehyde resorcinol calix[4]arene ligands as vertices and 12 dihydrazine benzoate ligands as edges. Preferably, the porous organic cage HPOC-401 crystal contains an ultra-large octahedral cavity and eight triangular windows.

[0025] According to an embodiment of the present invention, the maximum cavity diameter and volume of the porous organic cage HPOC-401 crystal are about 3.25 nm and

[0026] According to an embodiment of the present invention, the number of molecules Z in a unit cell of the porous organic cage HPOC-401 crystal is 4.

[0027] According to an embodiment of the present invention, the average length of the triangular windows of the porous organic cage HPOC-401 crystal is about 2.0 nm (which can pass molecules with a diameter of about 0.95 nm).

[0028] According to an embodiment of the present invention, the size of the porous organic cage HPOC-401 crystal is 1 to 3 mm, and the surface is relatively smooth.

[0029] According to an embodiment of the present invention, the porous organic cage HPOC-401 crystal is a light yellow tetrahedral crystal.

[0030] According to an embodiment of the present invention, the porous organic cage HPOC-401 crystal has the following characteristics: Figure 3 The crystal structure is shown.

[0031] According to an embodiment of the present invention, the porous organic cage HPOC-401 crystal has substantially Figure 7 The X-ray powder diffraction pattern is shown.

[0032] According to an embodiment of the present invention, the BET surface area of ​​the porous organic cage HPOC-401 crystal is 3.5 to 3.6 m 2 g -1 , for example 3.57m 2 g -1 .

[0033] The present invention also provides a method for preparing the composite material, which comprises mixing the porous organic cage compound with a precursor containing a Ti active metal component, and reacting the mixture to obtain the composite material.

[0034] According to an embodiment of the present invention, the precursor containing the Ti active metal component may be titanyl acetylacetonate.

[0035] Preferably, the reaction mass volume ratio (mg:mL) of the porous organic cage compound to the precursor containing the Ti active metal component is (1-5):1, exemplified by 1:1, 2:1, 3:1, 4:1, and 5:1.

[0036] According to an embodiment of the present invention, the reaction temperature is room temperature; for example, the reaction time is 12-24 hours, for example, 24 hours.

[0037] Preferably, the preparation method further comprises a process of performing solid-liquid separation on the reaction system to obtain a reaction product after the reaction is completed. For example, the solid-liquid separation can be performed by means known in the art, such as filtration.

[0038] According to an embodiment of the present invention, the preparation method further comprises washing the reaction product obtained by solid-liquid separation. For example, the washing solvent may be methanol. For another example, the washing may be performed once, twice, or more times.

[0039] According to an embodiment of the present invention, the preparation method further includes drying the washed reaction product. For example, the drying method may be vacuum drying. Preferably, the drying temperature may be 60-100°C, exemplarily 100°C, and the drying time may be 6-20 hours, for example 12 hours.

[0040] According to an embodiment of the present invention, the preparation method of the composite material comprises placing HPOC-401 in a titanium acetylacetonate solution, soaking the solution at room temperature, and then filtering, washing, and drying the solution to obtain a red powdered composite material HPOC-401-Ti.

[0041] The present invention also provides the use of the composite material as a photocatalytic material, preferably in the photocatalytic degradation of dye pollutants.

[0042] According to an embodiment of the present invention, the dye pollutants include but are not limited to methylene blue, rhodamine B, and methyl orange.

[0043] Beneficial effects of the present invention:

[0044] Porous organic cages (POCs) are a new type of porous material that has emerged in recent years. They contain cavities of a specific size and are stacked into an ordered structure by discrete building units through weak interactions. Their pores are composed of cavities within the cage and stacked through-holes. They have potential application prospects in the fields of gas storage and separation, sensing, catalysis, and smart materials. Because their structure contains abundant nitrogen, oxygen and other sites, they can be modified by post-synthetic metalation (PSM) methods to the original POC. Studies have shown that a variety of metals, such as iron, cobalt, silver, and gold, can be loaded on the surface or cavity of POC to modify its performance. In view of this:

[0045] The present invention proposes a POC material functionalized with metallic titanium. The titanium-modified POC material not only combines the high specific surface area of ​​the POC material to enable the material to efficiently enrich pollutants in water; at the same time, the POC can sensitize the titanium metal sites, thereby increasing the material's absorption spectrum of sunlight, thereby promoting the photocatalytic degradation performance of the metal sites on dye pollutants in water.

[0046] The present invention utilizes resorcinol calix[4]arene-based porous organic cage HPOC-401 as a raw material and obtains a titanium-porous organic cage HPOC-401-Ti photocatalyst with highly dispersed metal sites through a post-modification metallization reaction (PSM). This provides a novel method for preparing inorganic-organic composite photocatalysts containing titanium. The method requires inexpensive materials, has a simple preparation process, is easy to operate, has a low reaction temperature, and the product has a large specific surface area, good stability and reproducibility, and is highly operable and practical. The method has potential application value and strong practicality in the photocatalytic degradation of dye pollutants in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the preparation of HPOC-401 according to the present invention.

[0048] Figure 2 This is a picture of the powdered HPOC-401 sample after removing the solvent molecules.

[0049] Figure 3 Schematic diagram of the synthesis of porous organic cage HPOC-401.

[0050] Figure 4 The H NMR spectra of HPOC-401 and HPOC-401 after being immersed in water ( 1 1H NMR).

[0051] Figure 5 This is the high-resolution mass spectrum (HR-MS) of HPOC-401.

[0052] Figure 6 This is the infrared spectrum (FT-IR) of HPOC-401.

[0053] Figure 7 This is the powder X-ray diffraction (PXRD) pattern of HPOC-401.

[0054] Figure 8 This is the thermogravimetric curve (TGA) of HPOC-401.

[0055] Figure 9 This is the N2 adsorption-desorption curve of HPOC-401.

[0056] Figure 10 This is a picture of the powdered HPOC-401-Ti sample after removing the solvent molecules.

[0057] Figure 11 Schematic diagram of the construction of polydispersed HPOC-401-Ti photocatalyst using post-synthetic metalation (PSM) synthesis method.

[0058] Figure 12 This is the scanning electron microscope SEM-EDS spectrum of HPOC-401-Ti.

[0059] Figure 13 This is the infrared spectrum (FT-IR) of HPOC-401-Ti.

[0060] Figure 14 This is the powder X-ray diffraction (PXRD) pattern of HPOC-401-Ti.

[0061] Figure 15 This is the molecular structure of HPOC-401-Ti.

[0062] Figure 16 This is the thermogravimetric analysis (TGA) diagram of HPOC-401-Ti under nitrogen atmosphere.

[0063] Figure 17 N2 adsorption-desorption curve of HPOC-401-Ti.

[0064] Figure 18 This is the ultraviolet-visible diffuse reflectance spectrum (UV-vis) of HPOC-401-Ti.

[0065] Figure 19 This is the UV-visible absorption spectrum of the photocatalytic degradation of methylene blue dye pollutant in water by HPOC-401-Ti.

[0066] Figure 20 This is the UV-visible absorption spectrum of the photocatalytic degradation of Rhodamine B dye pollutant in water by HPOC-401-Ti.

[0067] Figure 21 This is the UV-visible absorption spectrum of the photocatalytic degradation of methyl orange dye pollutant in water by HPOC-401-Ti. DETAILED DESCRIPTION

[0068] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0069] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0070] Example 1

[0071] The preparation method of HPOC-401-Ti comprises the following steps:

[0072] (1) A conventional solvent thermal method was used to synthesize HPOC-401 crystals based on hydroquinone cup[4]arene in a pressure tube. C4RACHO (C4RACHO = tetraaldehyde hydroquinone cup[4]arene, 81 mg, 0.1 mmol) and TPHA (TPHA = dihydrazine dibenzoate, 39 mg, 0.2 mmol) were dissolved in 12 mL of DMF (DMF = N,N-dimethylformamide). The solid sample was dissolved by ultrasonic cleaning for about 20 minutes, and then the solution was heated in an oil bath at 100°C for 12 hours. After that, the reaction solution was allowed to stand at room temperature for 12 hours to evaporate, and light yellow tetrahedral crystals were obtained. The grain size was 1-3 mm (such as Figure 1 Then, the mixture was filtered, washed with methanol, and exchanged with methanol several times. Finally, it was dried in a vacuum drying oven (100°C) for 12 hours to obtain HPOC-401 (as shown in the figure) in yellow powder form after the guest solvent molecules were removed. Figure 2 As shown), yield 70%.

[0073] HPOC-401 characterization methods:

[0074] (1) The structure of HPOC-401 was characterized by single crystal diffraction (SCXRD), and the results are shown in Table 1 below.

[0075] Table 1 is the crystallographic data of HPOC-401

[0076]

[0077]

[0078] R1 a =∑||F o |-|F c || / ∑|F o |. b wR2={∑[w(F o 2 -F c 2 ) 2 ] / ∑[w(F o 2 ) 2 ]} 1 / 2

[0079] The single crystal structure in Table 1 shows that HPOC-401 crystallizes in the orthorhombic Pnnn space group, and is composed of 6 tetraaldehyde resorcinol calix[4]arene ligands as vertices and 12 dibenzoic acid dihydrazine ligands as edges to form an octahedral organic cage. It contains an ultra-large octahedral cavity and 8 triangular windows. Its maximum cavity diameter and volume are approximately 3.25nm and In addition, the average length of the triangular window is about 2.0 nm, which can pass molecules with a diameter of about 0.95 nm (such as Figure 3 For simplicity, the isobutyl tail chain in HPOC-401 is not shown in the schematic structure).

[0080] (2) The dried HPOC-401 sample was subjected to nuclear magnetic proton spectroscopy ( 1 H NMR) characterization, the results are as follows Figure 4 The appearance of characteristic NH and HC=N peaks in the figure indicates the effective synthesis of the HPOC-401 organic cage. Subsequently, the HPOC-401 sample was immersed in water for a week and then dried and analyzed by H-NMR spectroscopy. The spectrum remained unchanged, confirming the stability of HPOC-401 in aqueous environments.

[0081] HPOC-401 was further characterized by high resolution mass spectrometry (HR-MS). Figure 5 A peak around 2281.3015 can be observed in the high-resolution mass spectrum, which can be attributed to HPOC-401 after the removal of three protons, thus confirming its water stability. The unchanged signal indicates the stability of HPOC-401 in water, thus indicating that it can also exist stably in the solution phase.

[0082] (3) Figure 6 The infrared spectrum (FT-IR) of HPOC-401 is shown. Through Fourier transform infrared spectroscopy (FT-IR) test, CN (1274 cm -1 )、C=N(1614cm -1 )、C=O(1670cm -1 ), OH and NH (3270 cm -1 ) characteristic infrared vibration signals, indicating that HPOC-401 is stable in solid state.

[0083] (4) Figure 7 : The X-ray powder diffraction (PXRD) pattern of HPOC-401 has a large broad peak in the range of 4-40°, which indicates that the HPOC-401 sample is amorphous after activation.

[0084] (5) Figure 8 This is the thermogravimetric curve (TGA) of HPOC-401. It can be seen from the thermogravimetric (TGA) analysis that HPOC-401 can be stable up to 320°C.

[0085] (6) Figure 9The N2 adsorption-desorption curve of HPOC-401 is shown in Figure 2. The BET test shows that the surface area of ​​HPOC-401 is 3.57 m 2 g -1 .

[0086] (2) The polydispersed HPOC-401-Ti (such as Figure 10 shown).

[0087] The powdered HPOC-401 (100 mg) was placed in 50 mL of saturated titanium acetylacetonate solution and soaked at room temperature for 24 h. It was then filtered, washed with methanol, and exchanged with methanol several times. Finally, it was dried in a vacuum drying oven (100 ° C) for 12 h to obtain a red powdered HPOC-401-Ti (such as Figure 11 This indicates that the present invention can obtain HPOC-401-Ti by simply soaking HPOC-401 in a saturated methanol solution of titanium acetylacetonate, with a yield of 87%.

[0088] HPOC-401-Ti characterization methods:

[0089] (1) The composition of HPOC-401-Ti was confirmed by field emission scanning electron microscopy (FE-SEM) and EDS spectroscopy, indicating that C, N, O, and Ti were uniformly distributed in HPOC-401-Ti. It also showed that Ti metal ions were successfully chelated on HPOC-401 (e.g. Figure 12 shown).

[0090] (2) The Ti content in the HPOC-401-Ti sample was determined to be 8.63% by plasma emission spectroscopy (ICP) characterization.

[0091] (3) Figure 13 The infrared spectrum (FT-IR) of HPOC-401-Ti is shown. CN (1290 cm -1 )、C=N(1614cm -1 )、C=O(1670cm -1 ), OH and NH (3270 cm -1 ) The characteristic infrared vibration signals have changed significantly. Among them, CN, C=N, and C=O have blue-shifted to 1274cm -1 、1567cm -1 、1602cm -1, which further indicates that Ti metal ions are successfully chelated on HPOC-401.

[0092] (4) Figure 14 : The X-ray powder diffraction (PXRD) pattern of HPOC-401-Ti has a broad peak in the range of 4-40°, which indicates that the HPOC-401-Ti sample is amorphous.

[0093] (5) HPOC-401-Ti was dried in a vacuum drying oven at 80°C for 5 h, and then subjected to thermogravimetric testing under a nitrogen atmosphere. The results are as follows: Figure 16 As shown in the thermogravimetric (TGA) analysis, HPOC-401 can be stable up to 300°C.

[0094] (6) The N2 adsorption-desorption curve of HPOC-401-Ti is as follows Figure 17 As shown in the figure, the nitrogen adsorption results at 77K show that the surface area of ​​HPOC-401-Ti is as high as 976.5m 2 g -1 .

[0095] (7) The UV-visible diffuse reflectance spectrum (UV-vis) of HPOC-401-Ti was tested by UV-vis. The results are as follows: Figure 18 As shown in the figure, it can be seen that the ultraviolet absorption edge of HPOC-401-Ti is located at 872nm, which can effectively absorb visible light. The corresponding energy band is 1.42eV, indicating that it has semiconductor properties.

[0096] (8) The degradation performance of HPOC-401-Ti on dye pollutants in water was determined by ultraviolet-visible absorption spectroscopy (UV). The specific method is as follows:

[0097] 5 mg of HPOC-401-Ti was added to 10 mL of 50 ppm methylene blue solution and exposed to sunlight for 5 hours. The degradation efficiency of HPOC-401-Ti on methylene blue in water was determined by ultraviolet-visible absorption spectroscopy (UV). The results are as follows: Figure 19 The results in the figure show that HPOC-401-Ti can degrade up to 99% of methylene blue in water under sunlight conditions.

[0098] 5 mg of HPOC-401-Ti was added to 10 mL of 50 ppm Rhodamine B solution, and 2 drops of hydrogen peroxide were added. The degradation efficiency of HPOC-401-Ti on Rhodamine B in water was determined by ultraviolet-visible absorption spectroscopy (UV). The results are as follows: Figure 20 The results in the figure show that after 5 hours of sunlight exposure, HPOC-401-Ti can degrade up to 99% of Rhodamine B in water.

[0099] 5 mg of HPOC-401-Ti was added to 10 mL of 50 ppm methyl orange solution and 2 drops of hydrogen peroxide were added. The degradation efficiency of HPOC-401-Ti on methyl orange in water was determined by ultraviolet-visible absorption spectroscopy (UV). The results are as follows: Figure 21 The results in the figure show that after 5 hours of sunlight exposure, HPOC-401-Ti can degrade up to 95% of methyl orange in water.

[0100] In summary, HPOC-401-Ti can efficiently degrade pollutants including methylene blue (>99%), rhodamine B (>99%), and methyl orange (>95%) under sunlight conditions.

[0101] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing a composite material, characterized in that: The preparation method comprises the steps of: 401 is placed in a titanium acetylacetonate solution and soaked at room temperature for 12-24 hours, followed by filtration, washing, and drying to obtain a red powdery composite material; The reaction mass volume ratio (mg:mL) of the porous organic cage compound and titanium acetylacetonate is (1-5): 1; The HPOC-401 is obtained by reacting tetraaldehyde resorcinol calix[4]arene (C4RACHO) and 4-dibenzoic acid dihydrazide (TPHA); the reaction temperature is 80-120°C and the reaction time is 6-20h; The molar ratio of tetraaldehyde resorcinol calix[4]arene (C4RACHO) to 4-dibenzoic acid dihydrazine (TPHA) is 1:(1-3); The composite material comprises a porous organic cage compound and metallic titanium supported on the porous organic cage compound; The molecular formula of the porous organic cage compound HPOC-401 is C 384 H 408 N 48 O 72 , having a structure as shown in Formula I: Formula I.

2. The method for preparing a composite material according to claim 1, wherein: In the composite material, the mass percentage of Ti is 5-10%.

3. The method for preparing a composite material according to claim 1 or 2, wherein: The BET surface area of ​​the composite material is 976~977 m 2 g -1 .

4. The method for preparing a composite material according to claim 1, wherein: The preparation method of HPOC-401 further comprises: evaporating the reaction liquid obtained after the reaction is completed at a constant temperature to obtain porous organic cage HPOC-401 crystals.

5. The method for preparing a composite material according to claim 1, wherein: The porous organic cage HPOC-401 crystal has a symmetry center, a space group of Pnnn, unit cell parameters of a=44.0956(9)Å, b=44.5782(8)Å, c=48.2469(9)Å, and α=β=γ=90°.

6. The method for preparing a composite material according to claim 1, wherein: The porous organic cage HPOC-401 crystal is an octahedral organic cage assembled by 6 tetraaldehyde resorcinol calix[4]arene ligands as vertices and 12 dihydrazine 4-dibenzoate ligands as edges.

7. The method for preparing a composite material according to claim 6, wherein: The porous organic cage HPOC-401 crystal contains an ultra-large octahedral cavity and eight triangular windows; And / or, the maximum cavity diameter and volume of the porous organic cage HPOC-401 crystal are 3.25 nm and 6800 Å 3 ; And / or, the number of molecules Z in a unit cell of the porous organic cage HPOC-401 crystal is 4; and / or, the average length of the triangular windows of the porous organic cage HPOC-401 crystal is 2.0 nm; And / or, the size of the porous organic cage HPOC-401 crystal is 1-3 mm; And / or, the porous organic cage HPOC-401 crystal is a light yellow tetrahedral crystal; And / or, the BET surface area of ​​the porous organic cage HPOC-401 crystal is 3.5-3.6 m 2 g -1 .

8. Use of the composite material prepared by the preparation method according to any one of claims 1 to 7 as a photocatalytic material in photocatalytic degradation of dye pollutants.

9. The use according to claim 8, wherein the dye pollutant is methylene blue, rhodamine B, or methyl orange.

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