A covalent organic framework material, and a preparation method and application thereof

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a covalent organic framework material and a preparation method and application thereof. The covalent organic framework material contains nitrogen-containing A units and B units in a structural unit; the nitrogen-containing A units are connected with the B units through nitrogen-carbon double bonds or nitrogen-carbon single bonds. The covalent organic framework material can produce hydrogen peroxide from pure water through ultrasonic and light irradiation in air without adding a sacrifice agent, has high piezoelectric photocatalytic performance, and the hydrogen peroxide and active oxygen species generated in the catalytic process can effectively degrade pollutants and significantly inhibit the growth and reproduction of bacteria, so that the degradation of pollutants and sterilization are simultaneously realized, the operation is simple, there is no secondary pollution, and the practicality is high.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a covalent organic framework material, its preparation method, and its application. Background Technology

[0002] Covalent organic frameworks (COFs) have attracted widespread attention in catalysis, environmental remediation, and other fields due to their regular pore structure, tunable photoelectric properties, and excellent chemical stability. However, existing COF materials suffer from limitations in variety and functional specificity: most COFs focus on a single application scenario, and the piezoelectric-photoelectric synergistic effect of traditional COFs has not been developed, resulting in low efficiency in piezoelectric photocatalytic hydrogen peroxide production; at the same time, their broad-spectrum degradation ability for complex pollutants is insufficient, and their long-term effectiveness and safety in antibacterial scenarios need to be improved. Although some COFs have been applied to single environmental fields, a multifunctional COF system that simultaneously covers piezoelectric photocatalytic hydrogen (oxygen) production, pollutant degradation, and antibacterial properties has not yet been realized, and there is a lack of research on the classification, design, and synergistic application of COFs with different structures. Summary of the Invention

[0003] In order to solve at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide a covalent organic framework material.

[0004] The second objective of this invention is to provide a method for preparing covalent organic framework materials.

[0005] The third objective of this invention is to provide a composite material.

[0006] The fourth objective of this invention is to provide a method for catalytic water splitting to produce hydrogen peroxide.

[0007] The fifth objective of this invention is to provide the application of the above-mentioned covalent organic framework material or the above-mentioned composite material in the fields of catalytic water splitting, pollutant degradation or sterilization.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a covalent organic framework material, wherein the structural units of the covalent organic framework material contain nitrogen-containing A units and B units; the nitrogen-containing A units and the B units are connected by nitrogen-carbon double bonds or nitrogen-carbon single bonds; The nitrogen-containing A unit is selected from , or ; The B unit is selected from , or ; Each Each is independently selected from N, or ; Each R2 is independently selected from hydroxyl, C 1-6 alkyl, C 1-6 alkoxy groups, , or ; Each Each independently selected , , , , or ; Each Each independently selected , , , , , , , , or ; Each R5 is independently selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy or ; n1 is an integer between 0 and 6; Each n2 is independently selected from integers between 0 and 5.

[0009] In this invention, " "This refers to the connection via a double bond, specifically the connection site of the double bond." "" refers to a connection through a single bond, which is a connection site of a single bond.

[0010] In some embodiments of the present invention, each R2 is independently selected from hydroxyl groups, , or .

[0011] In some embodiments of the present invention, each Each independently selected , or .

[0012] In some embodiments of the present invention, each Each independently selected , , , , or .

[0013] In some embodiments of the present invention, each R5 is independently selected from C. 2-6 alkyl, C 3-6 alkoxy or .

[0014] In some embodiments of the present invention, the C 1-6 The alkyl group is selected from methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, or 2-ethylbutyl.

[0015] In some embodiments of the present invention, the C 1-6 The alkoxy group is selected from methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, n-hexyloxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, or 2-ethylbutoxy.

[0016] In some embodiments of the present invention, n1 is 0, 1, 2, 3, 4, 5, or 6. In some embodiments of the present invention, n1 is an integer from 0 to 3.

[0017] In some embodiments of the present invention, each n2 is independently selected from 0, 1, 2, 3, 4, or 5. In some embodiments of the present invention, each n2 is independently selected from an integer from 1 to 4.

[0018] In some embodiments of the present invention, the covalent organic framework material is assembled from aldehyde monomers and amine monomers through an imine condensation reaction.

[0019] In some embodiments of the present invention, the raw materials for preparing the nitrogen-containing A unit include amine monomers.

[0020] In some embodiments of the present invention, the raw materials for preparing the B unit include aldehyde monomers.

[0021] In some embodiments of the present invention, the aldehyde monomer includes , or .

[0022] In some embodiments of the present invention, the amine monomer includes , or .

[0023] In some embodiments of the present invention, the structural units of the covalent organic framework material are composed of and It is assembled.

[0024] In some embodiments of the present invention, the structural units of the covalent organic framework material are composed of and Assembled; In some embodiments of the present invention, the structural units of the covalent organic framework material are composed of and It is assembled.

[0025] In some embodiments of the present invention, the structural units of the covalent organic framework material are selected from... , or .

[0026] In some embodiments of the present invention, the structural units of the covalent organic framework material are selected from... , , or .

[0027] The present invention provides the above-mentioned COF materials, wherein the pore-modified type introduces alkyl, alkoxy, polyfluoroalkyl, ether chain and hydroxypropyl ether groups through nucleophilic substitution or ring-opening reaction to break the crystal centrosymmetry, regulate the molecular dipole moment and enhance charge separation and transport to improve piezoelectric performance; the piezoelectric group functionalized type relies on benzothiadiazole and its derivatives to construct a non-centrosymmetric structure, enhance molecular polarization and enhance piezoelectric-photoelectric coupling; the photoelectric active unit doping type introduces calix[4] aromatic derivatives with electron donor-π conjugated bridge-electron acceptor (D-π-A) structure to enhance photogenerated carrier separation and construct a non-centrosymmetric polarized structure, and simultaneously improve photoelectric and piezoelectric performance.

[0028] A second aspect of the present invention provides a method for preparing the covalent organic framework material described in the first aspect of the present invention, the method comprising the following steps: The covalent organic framework material is formed by assembling aldehyde monomers and amine monomers through an imine condensation reaction.

[0029] In some embodiments of the present invention, the aldehyde monomer includes , or .

[0030] In some embodiments of the present invention, the reaction temperature of the imine condensation reaction is 50~150°C; in some embodiments of the present invention, the reaction temperature of the imine condensation reaction is any value or a range formed by any two of 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C, such as 80~90°C or 120°C.

[0031] In some embodiments of the present invention, the imine condensation reaction takes 1 to 72 hours, such as 24 to 26 hours or 72 hours.

[0032] In some embodiments of the present invention, the amine monomer includes , or .

[0033] A third aspect of the present invention provides a composite material comprising a complex formed by hydrogen bonding of a covalent organic framework material as described in the first aspect of the present invention and a fluoropolymer.

[0034] In some embodiments of the present invention, the fluoropolymer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, perfluoroethylene propylene, polychlorotrifluoroethylene, perfluorosulfonic acid resin, and ethylene-chlorotrifluoroethylene copolymer.

[0035] A fourth aspect of the present invention provides a method for producing hydrogen peroxide by catalytic water splitting, the method comprising the following steps: The covalent organic framework material described in the first aspect of the present invention or the composite material described in the third aspect of the present invention is mixed with water, and hydrogen peroxide is produced by catalytic water decomposition under light and / or ultrasound.

[0036] In some embodiments of the present invention, the illumination refers to the irradiation with ultraviolet light and / or visible light.

[0037] In some embodiments of the present invention, the wavelength of the visible light is 380 nm to 760 nm, such as 400 nm to 760 nm or 420 nm to 760 nm.

[0038] In some embodiments of the present invention, the wavelength of the ultraviolet light is 10 nm to 380 nm, such as 50 nm to 380 nm.

[0039] In some embodiments of the present invention, the intensity of the light is 50~150 W / m². 2 .

[0040] In some embodiments of the present invention, the frequency of the ultrasound is 20 kHz to 60 kHz.

[0041] The fifth aspect of the present invention provides the application of the covalent organic framework material described in the first aspect of the present invention or the composite material described in the third aspect of the present invention in the fields of catalytic water splitting, pollutant degradation or sterilization.

[0042] In some embodiments of the present invention, the contaminant includes at least one of Rhodamine B, methylene blue, and methyl orange.

[0043] In some embodiments of the present invention, the bactericidal strain includes at least one of Staphylococcus aureus and Escherichia coli.

[0044] In some embodiments of the present invention, the products formed by the catalytic water splitting include at least one of hydrogen peroxide, oxygen, reactive oxygen, and hydrogen.

[0045] This invention utilizes covalent organic framework materials or composite materials to generate hydrogen peroxide and reactive oxygen species (·OH, ·O2) during the catalytic water splitting process. - , 1 O2 can be used to degrade pollutants and kill bacteria.

[0046] The beneficial effects of this invention are as follows: the covalent organic framework material of this invention can decompose pure water to produce hydrogen peroxide in air by ultrasound and light without the addition of sacrificial agents. It has highly efficient piezoelectric photocatalytic performance, and the hydrogen peroxide and reactive oxygen species generated during the catalytic process can effectively degrade pollutants (such as Rhodamine B, methylene blue, methyl orange) and significantly inhibit the growth and reproduction of bacteria (such as Staphylococcus aureus and Escherichia coli). It simultaneously achieves pollutant degradation and sterilization, is suitable for integrated water treatment scenarios, is easy to operate, has no secondary pollution, and is highly practical. Attached Figure Description

[0047] Figure 1 The images show the infrared spectrum, solid-state carbon NMR spectrum, powder X-ray diffraction, and scanning electron microscopy results of COF-A1 in Example 1.

[0048] Figure 2 The images show the powder X-ray diffraction and solid-state carbon NMR spectrum of COF-A2 in Example 1.

[0049] Figure 3 The images show the UV-Vis diffuse reflectance spectrum, Tauc plot, Mott-Schottky curve, valence band X-ray photoelectron spectrum, and energy level test diagram of COF-A2 in Example 1.

[0050] Figure 4 The diagram shows the resonance peak, phase hysteresis loop, and amplitude butterfly loop of COF-A2 under different applied voltages in Example 1.

[0051] Figure 5 The graph shows the bactericidal performance of COF-A2 in catalyzing the degradation of Rhodamine B under different conditions and the piezoelectric catalytic reaction solution in Example 1.

[0052] Figure 6 The images show the infrared spectrum, powder X-ray diffraction, scanning electron microscope, and transmission electron microscope images of COF-B in Example 2.

[0053] Figure 7 The images show the UV-Vis diffuse reflectance spectrum, Tauc plot, Mott-Schottky curve, valence band X-ray photoelectron spectrum, and energy level test diagram of COF-B in Example 2.

[0054] Figure 8 The diagram shows the resonance peak, phase hysteresis loop, and amplitude butterfly loop of COF-B under different applied voltages in Example 2.

[0055] Figure 9 The graph shows the bactericidal performance of COF-B catalyzing the degradation of Rhodamine B under different conditions and the piezoelectric catalytic reaction solution in Example 2.

[0056] Figure 10 This is a schematic diagram of the 3D simulation structure of COF-C in Example 3.

[0057] Figure 11 The images show the infrared spectrum, solid-state carbon NMR spectrum, powder X-ray diffraction, and scanning electron microscope images of COF-C in Example 3.

[0058] Figure 12 The images show the UV-Vis diffuse reflectance spectrum, Tauc plot, Mott-Schottky curve, valence band X-ray photoelectron spectrum, and energy level diagram of COF-C in Example 3.

[0059] Figure 13 The diagram shows the resonance peak, phase hysteresis loop, and amplitude butterfly loop of COF-C under different applied voltages in Example 3.

[0060] Figure 14 The graph shows the performance test results of COF-C in Example 3 for piezoelectric photocatalytic degradation of pollutants and catalytic degradation of Rhodamine B under different conditions.

[0061] Figure 15 The graph shows the bactericidal performance of PVDF@COF-A1 in Example 4 under different conditions in catalyzing the degradation of Rhodamine B and the piezoelectric catalytic reaction solution.

[0062] Figure 16 This diagram illustrates the piezoelectric photocatalytic mechanism of the covalent organic framework material of this invention across multiple application scenarios. Detailed Implementation

[0063] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0064] Example 1 This embodiment prepares a pore-modified covalent organic framework material, denoted as COF-A2. COF-A2 is characterized by the introduction of a glycidyl ether fragment after glycidyl ring-opening via a nucleophilic ring-opening reaction using a phenolic hydroxyl group as the nucleophilic site. The structural formula of its repeating unit is shown below:

[0065] The specific synthesis steps of the organic framework material in this example are as follows:

[0066] 1,3,5-Tris(4-aminophenyl)benzene (TAPB, 21.1 mg, 0.06 mmol), 2,5-dihydroxyterephthalaldehyde (25DHTA, 15.0 mg, 0.09 mmol), o-dichlorobenzene (0.50 mL), n-butanol (0.50 mL), and an aqueous solution of acetic acid (0.10 mL, 6 mol / L) were mixed in a Pyrex tube. The mixture was sonicated for 10 minutes to homogenize. The Pyrex tube was rapidly frozen in a liquid nitrogen bath at 77 K, followed by three freeze-evacuation-thawing cycles, and then evacuated to an internal pressure of 100 mTorr. After sealing, the tube was heated to 120 °C for 3 days. A brown precipitate was obtained by centrifugation, followed by washing with tetrahydrofuran and anhydrous acetone. The powder sample was dispersed in dimethyl sulfoxide and stirred for 6 hours for activation. Then it was thoroughly washed with tetrahydrofuran. The solid was collected and dried under vacuum at 60°C for 12 hours to obtain orange powder COF-A1 (30 mg, yield 83%).

[0067]

[0068] COF-A1 (10.0 mg), glycidyl ether (0.20 mL), and anhydrous ethanol (5.00 mL) were added to a round-bottom flask and sonicated to ensure uniform dispersion. The reaction mixture was then heated to reflux and reacted for 24 h. After cooling, the mixture was filtered and washed with anhydrous ethanol to remove unreacted glycidyl ether. The solid was collected and dried under vacuum at 70 °C for 12 h to obtain 11.6 mg of red powder COF-A2.

[0069] The FT-IR plot of COF-A1 is shown below. Figure 1 As shown in Figure (A); solid COF-A1 13 CCP / MAS NMR spectrum as shown Figure 1 As shown in Figure (B), it is achieved through cross-polarization / magic angle rotation (CP / MAS). 13 The spectrum obtained by nuclear magnetic resonance spectroscopy; the powder X-ray diffraction (PXRD) spectrum of COF-A1 is as follows. Figure 1 As shown in Figure (C); the SEM image of COF-A1 is shown in Figure (C). Figure 1 As shown in Figure (D) of the diagram. (From...) Figure 1 3428 cm in Figure (A) -1 and 3346 cm -1 The primary amino group signal disappears at 1668 cm. -1 The appearance of imine signals, and Figure 1 The presence of the imine carbon signal at 153 ppm in Figure (B) confirms the successful synthesis of COF-A1. Figure 1 Figures (C) and (D) confirm that COF-A1 has a highly crystalline two-dimensional layered structure. The PXRD pattern of COF-A2 is shown below. Figure 2 As shown in Figure (A), the solid COF-A2 13 CCP / MAS NMR spectra as follows Figure 2 As shown in Figure (B) of the diagram. From Figure 2 It can be seen that the glycidyl fragment was successfully introduced through modification, while the crystallinity was preserved.

[0070] The light-harvesting performance and band gap of COF-A2 were evaluated using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The UV-visible diffuse reflectance spectrum is shown below. Figure 3 As shown in Figure (A), the Tauc plot curve is as follows: Figure 3 As shown in Figure (B) of the diagram. From Figure 3 Figures (A) and (B) show that the absorption initiation wavelength of COF-A2 is 585 nm, and the direct optical band gap is 2.17 eV, indicating that COF-A2 has a broad absorption spectrum in the visible light range, further demonstrating its strong photocatalytic potential. The electronic band positions of COF-A2 were determined by Mott-Schottky (MS) spectroscopy and valence band X-ray photoelectron spectroscopy (VB-XPS). The results of the Mott-Schottky (MS) spectroscopy performed in 0.5 M sodium sulfate aqueous solution are shown below. Figure 3 As shown in Figure (C), the test frequencies were 500 Hz, 1000 Hz, and 1500 Hz; the valence band X-ray photoelectron spectroscopy (VB-XPS) test results are as follows. Figure 3 As shown in Figure (D) of the diagram. (From...) Figure 3As shown in Figure (C), COF-A2 exhibits typical n-type semiconductor characteristics, with its Fermi level (E) relative to the standard hydrogen electrode (NHE) being... f The value is -0.89 V. (By...) Figure 3 As shown in Figure (D), the E of COF-A2 f The energy difference between the valence band (VB) and conduction band (CB) levels is 2.03 eV. Therefore, the valence band level of COF-A2 is 1.14 V relative to the standard hydrogen electrode, and its conduction band (CB) level is -1.03 V relative to the standard hydrogen electrode. The energy level diagram of COF-A2 is shown below. Figure 3 As shown in Figure (E), the results indicate that the positions of the conduction band and valence band of COF-A2 are suitable for promoting oxygen reduction and water oxidation reactions.

[0071] The piezoelectric properties of COF-A2 were tested using piezoelectric force microscopy, and the resonance diagrams under different applied voltages are shown below. Figure 4 As shown in Figure (A), the phase hysteresis loop and amplitude butterfly loop diagram are as follows: Figure 4 As shown in Figure (B) of the diagram. From Figure 4 As shown in Figure (A), COF-A2 exhibits a distinct resonance peak at 62 kHz, indicating voltage-induced piezoelectric vibrations within the COF-A2 material. Furthermore, a significant linear correlation between the vibration amplitude and the applied excitation voltage is observed, confirming the linear piezoelectric properties of the COF-A2 material. Figure 4 As shown in Figure (B), the butterfly-shaped amplitude hysteresis loop and phase curve further demonstrate the strong piezoelectricity of COF-A2. Under a scanning bias voltage ranging from -5 to 5 V, the maximum effective piezoelectric coefficient of COF-A2 was measured to be approximately 13.41 nm·V. -1 These results demonstrate that COF-A2 possesses strong intrinsic piezoelectricity.

[0072] The piezoelectric photocatalytic hydrogen peroxide production performance of COF-A2 material was tested under conditions of no sacrificial agent, ultrasound, or simultaneous ultrasound and light irradiation. The specific test method was as follows: 2 mg of covalent organic framework material was added to a quartz reactor, followed by 20 mL of pure water. The reactor was then subjected to ultrasound (40 kHz) for 2.5 hours, or to a combination of light and ultrasound (visible light > 420 nm and 40 kHz ultrasound) for 2.5 hours. A certain amount of liquid was collected every 30 minutes for hydrogen peroxide detection. The quantification of hydrogen peroxide was performed using TMB. H2O2 The HRP enzymatic assay was performed using horseradish peroxidase as a transient catalyst for the reaction between hydrogen peroxide and tetramethylbenzidine. Preparation of the 3,3',5,5'-tetramethylbenzidine (TMB) solution: 0.015 g TMB was dissolved in 0.3 mL of dimethyl sulfoxide, followed by the addition of 5 mL of glycerol and 45 mL of deionized water containing 0.02 g ethylenediaminetetraacetic acid and 0.095 g citric acid. The solution was then brought to a final volume of 500 mL with deionized water. Preparation of the horseradish peroxidase (HRP) solution: 0.002 g HRP was dissolved in 10 μL of deionized water. Construction of the calibration curve: 200 μL of TMB solution and 10 μL of HRP solution were added to a hydrogen peroxide solution of known concentration. After 3 minutes, 10 μL of hydrochloric acid was added, and the resulting solution was analyzed by UV-Vis spectroscopy at 450 nm. The concentration of hydrogen peroxide in the sample was estimated using the linear relationship between signal intensity and hydrogen peroxide concentration. Under visible light (λ > 420 nm) irradiation and ultrasonic (40 kHz) conditions, the hydrogen peroxide production efficiency of COF-A2 was 4551 μmol / g / h; under ultrasonic (40 kHz) conditions only, the hydrogen peroxide production efficiency of COF-A2 was 3686 μmol / g / h.

[0073] The piezoelectric photocatalytic degradation of Rhodamine B (RhB) by COF-A2 was conducted as follows: Rhodamine B (RhB, 1 mg) was dissolved in 100 mL of pure water to prepare a 10 mg / L pollutant solution. 2 mg of covalent organic framework material was added to a quartz reactor, followed by 20 mL of the above pollutant solution. After stirring in the dark for 30 minutes, the reactor was subjected to ultrasonic / light irradiation and ultrasonic treatment. A certain amount of liquid was taken at regular intervals to record the color change over time. The absorbance of the solution was measured at a wavelength of λ = 552 nm (RhB) using a UV-Vis spectrophotometer. The performance test graph of COF-A2 catalyzing the degradation of Rhodamine B under different conditions is shown in the figure. Figure 5 As shown in Figure (A). From Figure 5 As shown in Figure (A), the C / C ratio slightly decreased during the dark adsorption stage (before 0 min), indicating that the COF-A2 material adsorbs pollutants. From 0 min onwards, the curves showed a significant decrease after applying light (λ > 420 nm) and ultrasound (40 kHz), or ultrasound only (40 kHz), indicating a catalytic degradation process. With increasing reaction time, the C / C ratio of RhB continued to decrease. Under the combined use of light and ultrasound, RhB was almost completely degraded after 45 min; even under ultrasound only, COF-A2 showed a significant degradation effect on RhB.

[0074] The sterilization of the piezoelectric catalytic water splitting reaction solution of COF-A2 material was tested. The specific experimental method was as follows: 1 mL of Staphylococcus aureus and Escherichia coli were inoculated into 50 mL of nutrient broth and cultured at 150 rpm for 12 hours in a shaker at 37°C. The bacterial solutions were then diluted 10... 5 Then, 400 μL of the diluent was added to each of the following groups of materials: 0.01 M phosphate-buffered saline (PBS), COF-A2 material (2 mg), and reaction solution in pure water (20 mL) sonicated for 1 h. The mixture was then incubated for 2 hours at 150 rpm in a shaker at 37°C. Afterward, 200 μL of the mixture was spread onto nutrient agar plates, which were then inverted and incubated at 37°C for 12 hours. Finally, the plates were removed to observe the number of bacterial strains. The piezoelectric catalytic reaction solution bactericidal performance test graph of COF-A2 is shown below. Figure 5 As shown in Figure (B) of the diagram. From Figure 5 As shown in Figure (B), the reaction solution produced by COF-A2 under ultrasonic (40 kHz) conditions for 60 minutes can significantly inhibit the growth of Escherichia coli and Staphylococcus aureus.

[0075] Example 2 This embodiment prepares a piezoelectric functionalized covalent organic framework material, denoted as COF-B. The structural feature of COF-B is the introduction of benzothiadiazole groups as piezoelectric functional units, and the structural formula of its repeating unit is as follows:

[0076] The covalent organic framework material in this example was prepared using the following synthetic method, the specific steps of which are as follows:

[0077] 2,4,6-Trihydroxybenzene-1,3,5-tricarboxaldehyde (TP, 10.5 mg, 0.05 mmol), 4,4'-(benzo-2,1,3-thiadiazol-4,7-diyl)diphenylamine (BT-NH2, 23.9 mg, 0.08 mmol), o-dichlorobenzene (0.75 mL), n-butanol (0.25 mL), and pyridine (0.10 mL) were mixed in a Pyrex tube. The mixture was sonicated for 10 minutes to homogenize. The tube was then rapidly frozen in a liquid nitrogen bath at 77 K, followed by three freeze-evacuation-thawing cycles, and then evacuated to an internal pressure of 100 mTorr. After sealing, the tube was heated to 120 °C. oC, and kept for 3 days. A brown precipitate was obtained by centrifugation, followed by washing with tetrahydrofuran and anhydrous acetone. The powder sample was activated by stirring in dimethyl sulfoxide for 6 hours, then thoroughly washed with tetrahydrofuran, and the solid was collected and vacuum dried at 60 °C for 12 hours to obtain orange powder COF-B (26.0 mg, yield 75%).

[0078] The FT-IR plot of COF-B is shown below. Figure 6 As shown in Figure (A), the PXRD spectrum of COF-B is as follows: Figure 6 As shown in Figure (B), the SEM image of COF-B is as follows. Figure 6 As shown in Figure (C), the TEM image of COF-B is as follows. Figure 6 As shown in Figure (D), Figure 6 A magnified view of the boxed area in Figure (D) is shown below. Figure 6 As shown in Figure (E). Figure 6 Figure (A) shows 1619 cm. -1 β-ketoenamine structural features, C=O signal, 1451 cm⁻¹ -1 C=C signal, 1253 cm -1 CN signal and 950 cm -1 The appearance of the characteristic peak of the benzothiadiazole (BT) unit confirmed the successful synthesis of COF-B. Figure 6 As can be seen from the three sub-figures (B), (C) and (D), COF-B has a highly crystalline two-dimensional sheet structure.

[0079] The light-harvesting performance and band gap of COF-B were evaluated using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The UV-visible diffuse reflectance spectrum of COF-B is shown below. Figure 7 As shown in Figure (A), the Tauc plot curve test graph is as follows. Figure 7 As shown in Figure (B) of the diagram. From Figure 7 Figures (A) and (B) show that the absorption initiation wavelength of COF-B is 599 nm, and the direct optical band gap is 2.07 eV, indicating that COF-B has a broad absorption spectrum in the visible light range, thus suggesting that COF-B has strong photocatalytic potential. The electronic band positions of COF-B were determined by Mott-Schottky (MS) measurement and valence band X-ray photoelectron spectroscopy (VB-XPS). The results of the Mott-Schottky (MS) measurement performed in 0.5 M sodium sulfate aqueous solution are shown below. Figure 7 As shown in Figure (C), the test frequencies were 500 Hz, 1000 Hz, and 1500 Hz; the valence band X-ray photoelectron spectroscopy (VB-XPS) test results are as follows. Figure 7 As shown in Figure (D) of the diagram. (From...) Figure 7As shown in Figure (C), COF-B exhibits typical n-type semiconductor characteristics, with its Fermi level (E) relative to the standard hydrogen electrode (NHE) being... f The value is -0.79 V. (By...) Figure 7 As shown in Figure (D), the E of COF-B f The energy difference between the valence band (VB) and conduction band (CB) levels is 1.98 eV. Therefore, the valence band level of COF-B is 1.19 V relative to the standard hydrogen electrode, and its conduction band (CB) level is -0.88 V relative to the standard hydrogen electrode. The energy level diagram of COF-B is shown below. Figure 7 As shown in Figure (E), the results indicate that the positions of the COF-B conduction band and valence band are suitable for promoting oxygen reduction and water oxidation reactions.

[0080] The piezoelectric properties of COF-B were tested using piezoelectric force microscopy, and the resonance peak diagrams under different applied voltages are shown below. Figure 8 As shown in Figure (A), the phase hysteresis loop and amplitude butterfly loop diagram are as follows: Figure 8 As shown in Figure (B) of the diagram. From Figure 8 As shown in Figure (A), COF-B exhibits a distinct resonance peak at 112 kHz, indicating voltage-induced piezoelectric vibrations within the COF-B material. Furthermore, a significant linear correlation between the vibration amplitude and the applied excitation voltage is observed, confirming the linear piezoelectric properties of the COF-B material. Figure 8 As shown in Figure (B), the butterfly-shaped amplitude hysteresis loop and phase curve of the COF-B material further demonstrate its strong piezoelectricity. Under a scanning bias voltage ranging from -5 to 5 V, the maximum effective piezoelectric coefficient of COF-B was measured to be approximately 0.92 nm·V. -1 These results demonstrate that COF-B possesses strong intrinsic piezoelectricity.

[0081] The piezoelectric photocatalytic hydrogen peroxide production performance of COF-B material was tested under conditions of no sacrificial agent, ultrasound, or simultaneous ultrasound and light irradiation, using the same testing method as in Example 1. Under visible light (λ > 420 nm) irradiation and ultrasound (40 kHz) conditions, the hydrogen peroxide production efficiency of COF-B was 1258 μmol / g / h; under ultrasound only (40 kHz) conditions, the hydrogen peroxide production efficiency of COF-B was 876 μmol / g / h.

[0082] The piezoelectric photocatalytic degradation of Rhodamine B (RhB) by COF-B was conducted as follows: the testing method was the same as in Example 1. The performance test results of COF-B in catalyzing the degradation of Rhodamine B under different conditions are shown in the figure. Figure 9 As shown in Figure (A). From Figure 9As shown in Figure (A), the C / C ratio decreased slightly during the dark adsorption stage (before 0 min), indicating that the COF-B material has adsorption properties for pollutants. From 0 min onwards, when light irradiation (λ>420 nm) and ultrasound (40 kHz) or ultrasound (40 kHz) were applied respectively, the curves decreased significantly, indicating the catalytic degradation process. With the extension of reaction time, the C / C ratio of RhB continued to decrease, indicating that the surface COF-B has a significant degradation effect on RhB.

[0083] The sterilization performance of the piezoelectric catalytic water splitting reaction solution of COF-B material was tested using the same method as in Example 1. The test results for the sterilization performance of the COF-B piezoelectric catalytic reaction solution are shown in the figure below. Figure 9 As shown in Figure (B) of the diagram. From Figure 9 As shown in Figure (B), the reaction solution produced by COF-B under ultrasonic (40 kHz) conditions for 60 minutes can significantly inhibit the growth of Escherichia coli and Staphylococcus aureus.

[0084] Example 3 In this embodiment, a photoelectric active unit doped covalent organic framework material, denoted as COF-C, was prepared. The structural feature of this COF is the introduction of a calix[4] aromatic derivative containing an “electron donor-π conjugated bridge-electron acceptor (D-π-A)” structure as a photoelectric active unit. The structural formula of its repeating unit is as follows:

[0085] The covalent organic framework material in this example was prepared using a method that includes the following steps: (1) Synthesis of ligand intermediate C-1

[0086] Compound TH-C4 (25,26,27,28-tetrahydroxycalix[4]arene) (2.12 g, 5.00 mmol), sodium hydride (60% by mass, dispersed in mineral oil) (1.60 g, 0.96 g, 40.00 mmol as pure NaH) and 40 mL of anhydrous DMF were added to a 100 mL round-bottom flask and heated to 60 °C and stirred for 0.5 hours. Then 1-bromobutane (0.82 g, 6.00 mmol) was added, and the mixture was heated to 80 °C and stirred for 12 hours. After the reaction was completed, the system was quenched in 50 mL of ice water, and then extracted with 30 mL of dichloromethane. The organic phase was collected, washed with saturated brine, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized with 30 mL of anhydrous methanol. The solid was filtered, collected, and dried under vacuum at 60 °C overnight to obtain 2.79 g of white solid C-1, with a yield of 86%. 1¹H NMR (400 MHz, deuterated chloroform) δ (ppm): 6.61-6.52 (m, 12H), 4.43 (d, J = 13.32 Hz, 4H), 3.87 (t, J = 7.35 Hz, 8H), 3.13 (d, J = 13.46 Hz, 4H), 1.93-1.83 (m, 8H), 1.51-1.37 (m, 8H), 0.98 (t, J = 7.42 Hz, 12H).

[0087] (2) Synthesis of ligand intermediate C-2

[0088] Ligand intermediate C-1 (1.30 g, 2.00 mmol) and 50 mL of 2-butanone were added to a 100 mL round-bottom flask, stirred until dissolved, and then placed in a 0°C container. o Add to C's ice water bath in batches N 1,78 g of bromosuccinimide (NBS, 1.78 g, 10.00 mmol) was added and allowed to rise naturally to room temperature. The reaction was then stirred for 24 hours. After the reaction was complete, saturated sodium thiosulfate aqueous solution was added to quench the reaction. Then, 50 mL of water and 30 mL of dichloromethane were added for extraction. The organic phase was collected, washed successively with saturated brine, dried over anhydrous sodium sulfate, and finally concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to give 1.52 g of white solid C-2, with a yield of 79%. 1 ¹H NMR (400 MHz, deuterated chloroform) δ (ppm): 6.80 (s, 8H), 4.34 (d, J = 13.4 Hz, 4H), 3.85 (t, J = 7.5 Hz, 8H), 3.08 (d, J = 13.5 Hz, 4H), 1.84 (p, J = 7.6 Hz, 8H), 1.41 (h, J = 7.4 Hz, 8H), 0.98 (t, J = 7.4 Hz, 12H).

[0089] (3) Synthesis of ligand intermediate C-3

[0090] Under a nitrogen atmosphere, ligand C-2 (0.48 g, 0.50 mmol), pinacol ester of 2,2'-bithiophene-5-boronic acid (1.17 g, 4.00 mmol), and Pd(PPh3)4 (0.23 g, 0.20 mmol) were added to a reaction flask, followed by 10 mL of a 2 mol / L aqueous solution of K2CO3 and 100 mL of ethylene glycol dimethyl ether. The mixture was heated to 85°C. o The reaction was stirred for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, and 50 mL of water and 30 mL of dichloromethane were added sequentially for extraction. The organic phase was collected, washed sequentially with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to give 0.36 g of yellow solid C-3, with a yield of 55%. 1 ¹H NMR (400 MHz, deuterated chloroform) δ (ppm): 7.11 (d, J = 5.2 Hz, 4H), 7.02(d, J = 3.5 Hz, 4H), 6.97-6.89 (m, 12H), 6.82 (d, J = 3.6 Hz, 4H), 6.73 (d, J =3.8 Hz, 4H), 4.49 (d, J = 13.3 Hz, 4H), 3.95 (t, J = 7.5 Hz, 8H), 3.23 (d, J =13.4 Hz, 4H), 1.97-1.90 (m, 8H), 1.52-1.46 (m, 8H), 1.03 (t, J = 7.4 Hz, 12H).

[0091] (4) Synthesis of ligand intermediate C-4

[0092] Ligand intermediate C-3 (0.46 g, 0.35 mmol) and 20 mL of chloroform were added to a 100 mL round-bottom flask, stirred until dissolved, and then placed in a 0°C container. o In an ice-water bath, NBS (0.26 g, 1.40 mmol) was added in batches. After the addition was complete, the mixture was allowed to rise naturally to room temperature, and the reaction was stirred for 12 hours. After the reaction was complete, saturated sodium thiosulfate aqueous solution was added to quench the reaction, followed by extraction with 30 mL of water and 20 mL of dichloromethane. The organic phase was collected, washed successively with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to give 0.46 g of yellow solid C-4, with a yield of 81%.1 H NMR (400 MHz, Chloroform- d ) δ (ppm): 6.92 (s, 8H), 6.87 (d, J = 3.9 Hz, 4H), 6.78 (d, J = 3.7Hz, 4H), 6.75-6.72 (m, 8H), 4.49 (d, J = 13.3 Hz, 4H), 3.95 (t, J = 7.4 Hz, 8H), 3.22 (d, J = 13.4 Hz, 4H), 1.97-1.89 (m, 8H), 1.53-1.42 (m, 8H), 1.02 (t, J = 7.4 Hz, 12H).

[0093] (5) Synthesis and characterization of organic ligand C-5:

[0094] Under a nitrogen atmosphere, compound C4-2SF-Br (i.e., ligand intermediate C-4, 100 mg, 0.06 mmol), 4-formylphenylboronic acid (76 mg, 0.50 mmol), and Pd(PPh3)4 (46 mg, 0.04 mmol) were added to a 100 mL reaction flask. Then, 2 mL of a 2 mol / L K2CO3 aqueous solution and 20 mL of DMF were added, and the mixture was heated to 100 °C and stirred for 12 hours. After the reaction was complete, the mixture was cooled to room temperature, and extracted successively with 50 mL of water and 30 mL of dichloromethane. The collected organic phase was washed successively with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to give 74 mg of orange solid C-5, with a yield of 72%. 1 ¹H NMR (400 MHz, deuterated chloroform) δ (ppm): 9.82 (s, 4H), 7.63 (d, J = 8.0 Hz, 8H), 7.46 (d, J = 8.0 Hz, 8H), 7.11 (d, J = 3.9 Hz, 4H), 6.94-6.85 (m, 12H), 6.74 (s, 4H), 4.45 (d, J = 13.3 Hz, 4H), 3.90 (t, J= 7.4 Hz, 8H), 3.19 (d, J = 13.5 Hz, 4H), 1.92-1.84 (m, 8H), 1.46-1.40 (m, 8H), 0.97 (t, J = 7.4 Hz, 12H). 13 C NMR (101 MHz, deuterated chloroform) δ (ppm): 13.08, 18.36, 31.26,52.41, 74.18, 121.68, 123.11, 123.89, 124.17, 124.65, 124.70, 127.03, 129.30,133.71, 133.90, 134.40, 138.42, 138.56, 139.22, 143.31, 155.71, 190.16.MALDI-TOF (m / z): [C 104 H 88 O8S8+H] + The calculation is: 1721.4245 ([M+H]) + The test revealed: 1721.4275 ([M+H]) + ).

[0095] (6) Synthesis and characterization of compound COF-C:

[0096] Compound C-5 (43 mg, 0.025 mmol), 4,4'-(benzo[C][1,2,5]thiadiazole-4,7-diyl)diphenylamine (BT-NH2, 16 mg, 0.05 mmol) were added to a 6.0 mm diameter Pyrex tube, followed by 0.5 mL of 6M aqueous acetic acid solution, 1.50 mL of mesitylene, and 1.50 mL of 1,4-dioxane. The mixture was ultrasonically dispersed for 10 minutes, then rapidly frozen and evacuated in a liquid nitrogen bath at 77.3 K. Thawing was performed at vacuum levels of 120 Pa and 80 Pa, respectively. After two cycles of freezing-evacuation-thawing, the Pyrex tube was sealed and placed in an oven at 120 °C for 3 days. After the reaction was completed, the mixture was filtered, washed with THF, and then dried under vacuum in an oven at 80°C to obtain an orange solid powder COF-C (34 mg, yield 58%).

[0097] The 3D simulation structure diagram of the COF-C of the compound in this example is shown below. Figure 10 As shown. The FT-IR spectrum of COF-C is as follows. Figure 11As shown in Figure (A), the solid COF-C 13 CCP / MAS NMR spectrum as shown Figure 11 As shown in Figure (B), the PXRD spectrum of COF-C is as follows: Figure 11 As shown in Figure (C), the SEM image of COF-C is as follows. Figure 11 As shown in Figure (D) of the diagram. (From...) Figure 11 In Figure (A), 3403cm -1 and 3333 cm -1 The primary amino group signal disappears at 1621 cm. -1 The appearance of imine signals, and Figure 11 The presence of an imine carbon signal at 153 ppm in Figure (B) confirms the successful synthesis of COF-C. Figure 11 Figures (C) and (D) confirm that COF-C has a highly crystalline spherical structure.

[0098] The light-harvesting performance and band gap of COF-C were evaluated using ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The UV-visible diffuse reflectance spectrum of COF-C is shown below. Figure 12 As shown in Figure (A), the Tauc plot curve is as follows: Figure 12 As shown in Figure (B) of the diagram. From Figure 12 Figures (A) and (B) show that the absorption initiation wavelength of COF-C is 525 nm, and the direct optical band gap is 2.27 eV, indicating that COF-C has a broad absorption spectrum in the visible light range, thus suggesting that COF-C has strong photocatalytic potential. The electronic band positions of COF-C were determined by Mott-Schottky (MS) spectroscopy and valence band X-ray photoelectron spectroscopy (VB-XPS). The results of the Mott-Schottky (MS) spectroscopy performed in 0.5 M sodium sulfate aqueous solution are shown below. Figure 12 As shown in Figure (C), the test frequencies were 800 Hz, 1000 Hz, 1200 Hz, and 1500 Hz; the valence band X-ray photoelectron spectroscopy (VB-XPS) test results are as follows. Figure 12 As shown in Figure (D) of the diagram. (From...) Figure 12 As shown in Figure (C), COF-C exhibits typical n-type semiconductor characteristics, with its Fermi level (E) relative to the standard hydrogen electrode (NHE) being... f The value is -0.84 V. (By...) Figure 12 As shown in Figure (D), the E of COF-C f The energy difference between the valence band (VB) and conduction band (CB) levels is 1.97 eV. Therefore, the valence band level of COF-C is 1.13 V relative to the standard hydrogen electrode, and its conduction band (CB) level is -1.14 V relative to the standard hydrogen electrode. The energy level diagram of COF-C is shown below. Figure 12 As shown in Figure (E), the results indicate that the positions of the conduction band and valence band of COF-C are suitable for promoting oxygen reduction and water oxidation reactions.

[0099] The piezoelectric properties of COF-C were tested using piezoelectric force microscopy. The resonance peak diagrams of COF-C under different applied voltages are shown below. Figure 13 As shown in Figure (A), the phase hysteresis loop and amplitude butterfly loop diagram are as follows: Figure 13 As shown in Figure (B) of the diagram. From Figure 13 As shown in Figure (A), COF-C exhibits a distinct resonance peak at 62 kHz, indicating voltage-induced piezoelectric vibrations within the COF-C material. Furthermore, a significant linear correlation between the vibration amplitude and the applied excitation voltage is observed, confirming the linear piezoelectric properties of the COF-C material. Figure 13 As shown in Figure (B), the butterfly-shaped amplitude hysteresis loop and phase curve of the COF-C material further demonstrate its strong piezoelectricity. Under a scanning bias voltage ranging from -5 to 5 V, the maximum effective piezoelectric coefficient of COF-C was measured to be approximately 17.13 nm·V. -1 These results demonstrate that COF-C possesses strong intrinsic piezoelectricity.

[0100] The piezoelectric photocatalytic hydrogen peroxide production performance of COF-C material was tested under conditions of no sacrificial agent, ultrasound, or simultaneous ultrasound and light irradiation, following the testing methods described in Example 1. Under visible light (λ > 420 nm) irradiation and ultrasound (40 kHz) conditions, the hydrogen peroxide production efficiency of COF-C was 1816 μmol / g / h; under ultrasound only (40 kHz) conditions, the hydrogen peroxide production efficiency of COF-C was 1373 μmol / g / h.

[0101] The following method was used to conduct experiments on the piezoelectric photocatalytic degradation of pollutants (i.e., methyl orange, rhodamine B, and methylene blue) using COF-C. Specifically, rhodamine B (RhB, 1 mg), methylene blue (MB, 1 mg), and methyl orange (MO, 1 mg) were dissolved in 100 mL of pure water to prepare 10 mg / L solutions of each pollutant. 2 mg of covalent organic framework material was added to a quartz reactor, followed by 20 mL of one of the above pollutant solutions. After stirring in the dark for 30 minutes, the reactor was subjected to ultrasonic / light irradiation and ultrasonic treatment. A certain amount of liquid was taken at regular intervals to record the color change over time. The absorbance of the solution was measured using a UV-Vis spectrophotometer at wavelengths λ = 552 nm (RhB), λ = 664 nm (MB), and λ = 464 nm (MO). Specific test results are shown below. Figure 14 As shown, where, Figure 14Figure (A) shows the degradation effect of COF-C on three pollutants under ultrasonic and light conditions. Figure 14 Figure (B) shows the degradation effect of COF-C on Rhodamine B under ultrasonic or ultrasonic and light irradiation conditions. Figure 14 It can be seen that the C / C ratio of the three pollutants decreased slightly during the dark adsorption stage (before 0 min), indicating that the COF-C material has a certain adsorption capacity for the three pollutants. After the application of light (λ>420 nm) and ultrasound (40 kHz) at 0 min, the curves dropped significantly, which corresponds to the piezoelectric photocatalytic degradation process. As the reaction time increased, the C / C ratio of the three pollutants continued to decrease, indicating that the COF-C material has a piezoelectric photocatalytic degradation effect on the three pollutants, and performs well in the degradation of RhB and methylene blue (MB). Both are basically completely degraded at 45 min. When only ultrasound is applied, COF-C also shows a significant degradation effect on RhB.

[0102] Example 4 This embodiment prepares a covalent organic framework-based composite material, denoted as PVDF@COF-A1, and the specific preparation process is as follows: Polyvinylidene fluoride (PVDF, 2 mg) and tetrahydrofuran (10 mL) were added to a 50 mL reaction flask. The mixture was stirred and heated to 50 °C in an oil bath until the PVDF was completely dissolved. Then, COF-A1 (10 mg) prepared in Example 1 was added, and the mixture was stirred and heated for another hour. After the reaction was completed, the mixture was concentrated under reduced pressure to remove the tetrahydrofuran. The solid was collected and dried under vacuum in a 60 °C oven to obtain 11.8 mg of red powder PVDF@COF-A1. In this composite material, the phenolic hydroxyl groups in COF-A1 act as hydrogen bond donors and are linked to a large number of highly electronegative fluorine atoms in PVDF via hydrogen bonds.

[0103] The piezoelectric photocatalytic hydrogen peroxide production performance of PVDF@COF-A1 material was tested under conditions of no sacrificial agent, ultrasound, or simultaneous ultrasound and light irradiation, using the same testing method as in Example 1. Under visible light (λ > 420 nm) irradiation and ultrasound (40 kHz) conditions, the hydrogen peroxide production efficiency of PVDF@COF-A1 was 3356 μmol / g / h; under ultrasound only (40 kHz) conditions, the hydrogen peroxide production efficiency of PVDF@COF-A1 was 2573 μmol / g / h.

[0104] The piezoelectric photocatalytic degradation of Rhodamine B using PVDF@COF-A1 was conducted using the same methods as in Example 1. The performance test results of PVDF@COF-A1 in catalyzing the degradation of Rhodamine B under different conditions are shown in the following figures. Figure 15 As shown in Figure (A). From Figure 15As shown in Figure (A), the C / C ratio slightly decreased during the dark adsorption stage (before 0 min), indicating that the PVDF@COF-A1 material has adsorption capacity for pollutants. From 0 min onwards, the curves showed a significant decrease after applying light irradiation (λ>420 nm) and ultrasound (40 kHz), or ultrasound only (40 kHz), indicating a catalytic degradation process. With the extension of reaction time, the C / C ratio of RhB continued to decrease. Under the combined use of light and ultrasound, RhB was almost completely degraded after 45 min. When ultrasound was used alone, PVDF@COF-A1 also showed a significant degradation effect on RhB.

[0105] The sterilization performance of the PVDF@COF-A1 material in the piezoelectric catalytic water splitting reaction solution was tested according to the method described in Example 1. The test results for the sterilization performance of the PVDF@COF-A1 piezoelectric catalytic reaction solution are shown in the figure below. Figure 15 As shown in Figure (B) of the diagram. From Figure 15 As shown in Figure (B), the reaction solution produced by PVDF@COF-A1 under ultrasonic (40 kHz) conditions for 60 minutes can significantly inhibit the growth of Escherichia coli and Staphylococcus aureus.

[0106] The piezoelectric photocatalytic multi-scenario application mechanism of the covalent organic framework material prepared in this invention is as follows: Figure 16 As shown, covalent organic framework (COF) materials, when activated by light and ultrasound, or ultrasound alone, catalyze water splitting to produce hydrogen peroxide and ·OH and ·O2. - , 1 O2 and other reactive oxygen species can be used for antibacterial and pollutant degradation.

[0107] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A covalent organic framework material, characterized in that: The structural units of the covalent organic framework material contain nitrogen-containing A units and B units; the nitrogen-containing A units and the B units are connected by nitrogen-carbon double bonds or nitrogen-carbon single bonds. The nitrogen-containing A unit is selected from , or ; The B unit is selected from , or ; Each of them Each is independently selected from N, or ; Each R2 is independently selected from hydroxyl, C 1-6 alkyl, C 1-6 alkoxy groups, , or ; Each Each independently selected , , , , or ; Each Each independently selected , , , , , , , , or ; Each R5 is independently selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy or ; n1 is an integer between 0 and 6; Each n2 is independently selected from integers between 0 and 5.

2. The covalent organic framework material according to claim 1, characterized in that: Each R2 is independently selected from hydroxyl groups, , or ; And / or, Each Each independently selected , or ; And / or, Each Each independently selected , , , , or ; And / or, Each R5 is independently selected from C 2-6 alkyl, C 3-6 alkoxy or ; And / or, n1 is an integer between 0 and 3; And / or, Each n2 is independently selected from integers from 1 to 4.

3. The covalent organic framework material according to claim 1, characterized in that: The structural unit of the covalent organic framework material is composed of and Assembled; Alternatively, the structural units of the covalent organic framework material are composed of and Assembled; Alternatively, the structural units of the covalent organic framework material are composed of and It is assembled.

4. The covalent organic framework material according to claim 1, characterized in that: The structural units of the covalent organic framework material are selected from... , , , , , or .

5. The method for preparing the covalent organic framework material according to any one of claims 1-4, characterized in that: The preparation method includes the following steps: The covalent organic framework material is formed by imine condensation reaction of aldehyde monomers and amine monomers.

6. The method for preparing the covalent organic framework material according to claim 5, characterized in that: The aldehyde monomers include , or ; And / or, the amine monomers include , or .

7. A composite material, characterized in that: This includes complexes formed by hydrogen bonding of a covalent organic framework material as described in any one of claims 1-4 and a fluoropolymer.

8. The composite material according to claim 7, characterized in that: The fluoropolymer includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, perfluoroethylene propylene, polychlorotrifluoroethylene, perfluorosulfonic acid resin, and ethylene-chlorotrifluoroethylene copolymer.

9. A method for producing hydrogen peroxide by catalytic water splitting, characterized in that: The method includes the following steps: The covalent organic framework material according to any one of claims 1-4 or the composite material according to any one of claims 7-8 is mixed with water, and hydrogen peroxide is produced by catalytic water splitting under light and / or ultrasound.

10. The application of the covalent organic framework material according to any one of claims 1-4 or the composite material according to any one of claims 7-8 in the fields of catalytic water splitting, pollutant degradation or sterilization.

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