COF material for improving photo-generated charge separation and preparation method and application thereof

Abstract

The invention relates to the field of covalent organic framework materials and photocatalytic organic reactions, in particular to a COF material for improving photo-generated charge separation and a preparation method and application of the COF material. According to the present invention, 1, 3, 5-tri (4-aminophenyl) benzene (TAPB) is adopted as a donor unit, and a novel D-A type multi-bibenzothiadiazole TPAB-DTT-COF covalent organic framework material using a conjugated unit 2, 1, 3-benzothiadiazole as an acceptor unit is prepared; tAPB is an excellent electron donor unit which is widely used at present, polybiphenyl thiadiazolyl is an electron withdrawing group, the combination and matching of TAPB and polybiphenyl thiadiazolyl enhance the electronegativity difference value in molecules, reduce the exciton binding energy, promote the transfer of electrons from TAPB to a DTT unit, enhance the in-plane transmission and exciton separation efficiency, dissociate excitons under illumination, and improve the efficiency of electron transfer. The TAPB-DTT-COF material has the advantages that the TAPB-DTT-COF material has obvious photocurrent response signal, more obvious charge transfer performance and good photocatalytic performance;

Description

Technical Field

[0001] The invention relates to the field of covalent organic framework materials and photocatalytic organic reactions, and in particular to a COF material for improving photogenerated charge separation, and a preparation method and application thereof. Background Art

[0002] With global warming and the deterioration of the ecological environment, the world will face the severe situation of the depletion of fossil energy such as coal and oil in the near future. However, these energy sources are non-renewable, and they will release gases and smoke that are harmful to the ecological environment during combustion and use. Therefore, the development of clean, efficient and sustainable new energy has become an important measure for sustainable development. Solar energy is an inexhaustible clean energy. Photocatalysis, which converts solar energy into chemical energy, has been recognized as one of the most important solutions to meet the current energy and environmental challenges. Covalent organic frameworks (COFs) are a class of porous materials with regular crystalline network structures. They have the advantages of light weight, high light / thermal stability and chemical stability, strong crystalline specific surface area, and adjustable band gap. They have received widespread attention in the fields of energy storage, catalysis, sensing and biotherapy. In recent years, they have become a frontier hotspot in the field of chemistry and materials science at home and abroad.

[0003] Enhancing light harvesting, photogenerated charge generation and charge transfer is the key to improving the photocatalytic activity of COF materials. Since organic materials have a small intrinsic electrostatic constant and strong Coulomb binding forces hinder the separation of excitons into free holes and electrons, reducing the exciton effect is an important direction for designing organic covalent framework materials. Among the many design strategies, the combination of electron-rich and electron-deficient parts to form a periodic ordered donor-acceptor structure is an effective way to achieve more efficient exciton separation and charge transfer, thereby improving photocatalytic performance. Although DA-type COF materials have made good progress, due to the inherent relatively small electrostatic constant of organic semiconductor materials, it is easy to lead to large exciton binding energy and low photogenerated charge separation efficiency, which ultimately leads to low photocatalytic activity of organic photocatalysts. Therefore, by selecting appropriate donor-acceptor units, it is easy to adjust the exciton binding energy and conjugated planarity within the molecule, thereby adjusting the photogenerated charge efficiency of organic catalysts. Summary of the invention

[0004] In order to more effectively achieve exciton separation and charge transfer, and thus improve the photocatalytic performance, the present invention uses 1,3,5-tris(4-aminophenyl)benzene (TAPB) as a donor unit, and prepares a new DA-type polyphenylthiadiazole-based TPAB-DTT-COF covalent organic framework material with a conjugated unit 2,1,3-benzothiadiazole DTT as an acceptor unit. TAPB is an excellent electron donor unit that is widely used at present, and the polyphenylthiadiazole group is an electron-withdrawing group. The combination of the two enhances the difference in electronegativity within the molecule, reduces the exciton binding energy, promotes the transfer of electrons from TAPB to the DTT unit, enhances the efficiency of in-plane transmission and exciton separation, and dissociates excitons under light, and then separates electron holes to form photocurrent. The obtained TAPB-DTT-COF material exhibits a significant photocurrent response signal, a more obvious charge transfer performance, and good photocatalytic performance.

[0005] In order to solve the problems existing in the prior art, the present invention aims to provide a COF material with improved photogenerated charge separation efficiency, and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A COF material for improving photogenerated charge separation is a TAPB-DTT-COF material, and the structural formula is shown in Formula I:

[0007] Formula Ⅰ.

[0008] The method for preparing a COF material for improving photogenerated charge separation comprises the following steps: (1) The synthesis of 7,7''-di(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT) is shown in Formula II:

[0009] Formula II; Take 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole, 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole, tri-tert-butylphosphine tetrafluoroborate, potassium phosphate aqueous solution and tetrahydrofuran, add them into a pressure-resistant reaction tube and mix well; degas with nitrogen, and then add Pd2(dba)3; heat the reaction and then cool to room temperature, and post-treat to obtain a yellow powder 7,7''-di(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT); (2) COF material synthesis: 7,7''-di(5,5-dimethyl-1,3-dioxy-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole DTT, 1,3,5-tri(4-aminophenyl)benzene (TAPB) and a mixed solution of o-dichlorobenzene / n-butanol with a volume ratio of 1:1 are mixed and ultrasonically treated, and then a mixed aqueous solution of trifluoroacetic acid and acetic acid is added; ultrasonication is performed again, and then flash freezing is performed in a liquid nitrogen bath, and then degassing is performed through three freeze-thaw-freeze cycles, vacuum sealing, and finally heating for reaction; after filtering, washing, and drying, a red powder of the COF material is obtained.

[0010] Preferably, in the step (1), the amount of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole is 378.31-597.7 mg, more preferably 378.31 mg, the amount of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzothiadiazole is 0.706-1.1154 g, more preferably 0.706 g, and the concentration of the potassium phosphate aqueous solution is 2 mol / L; the amount of tri-tert-butylphosphine tetrafluoroborate is 19.8 - 41.77 mg, preferably 19.8 mg.

[0011] Further preferably, the amount of catalyst Pd2(dba)3 used in step (1) is 17.9-37.67 mg.

[0012] Preferably, the heating temperature in step (1) is 80-90°C, more preferably 80°C.

[0013] Preferably, the heating time in step (1) is 24 to 26 hours.

[0014] Preferably, the post-treatment in step (1) is: extracting the reaction solution with ethyl acetate and saturated sodium chloride solution, then collecting the organic phase, drying it over anhydrous magnesium sulfate, and removing the solvent in vacuo; dissolving the obtained solid in dichloromethane, and purifying it by silica gel column chromatography to obtain a yellow powder monomer.

[0015] Preferably, in step (2), the mass ratio of 7,7''-di(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT) to 1,3,5-tri(4-aminophenyl)benzene (TAPB) is (26-27):10.

[0016] Preferably, in step (2), the ultrasonic treatment time is 1 min, the concentration of trifluoroacetic acid in the mixed aqueous solution of trifluoroacetic acid and acetic acid is 0.6 M, and the concentration of acetic acid is 6 M; and the temperature of the liquid nitrogen bath is 77 K.

[0017] Preferably, in step (2), the heating reaction temperature is 120° C.-130° C., and the heating time is 3 to 4 days.

[0018] Preferably, in step (2), washing is performed using tetrahydrofuran, dichloromethane, acetone and anhydrous ethanol respectively; and the drying condition is vacuum drying at 120° C. for 24 hours.

[0019] The invention discloses an application of the COF material for improving the separation of photogenerated charges in the photocatalytic production of sulfoxide from anisyl thioether.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a preparation method and application of a COF material based on a poly-benzothiadiazole group. The covalent organic framework material designed by the present invention introduces a benzothiadiazole group. On the one hand, the strong electron-withdrawing property can reduce the exciton binding effect within the molecule and promote the separation and transmission of photogenerated electrons and holes; on the other hand, the poly-benzothiadiazole unit can enhance the molecular conjugation, enhance the molecular crystallinity and stability, and promote the in-plane transmission and separation of carriers.

[0021] The covalent organic framework material prepared by the present invention has high stability, high crystallinity, high charge transfer efficiency and low charge recombination rate, can catalyze the oxidation of anisyl thioether to sulfoxide under light and has good universality, and can be widely used in medicines and pesticides. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is 7,7''-bis(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT) in Example 1 of the present invention. 1 H NMR spectra; Figure 2 is 7,7''-bis(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT) in Example 1 of the present invention. 13 C NMR spectra; Figure 3 is the chemical reaction formula of TAPB-DTT-COF of the present invention; Figure 4 is the PXRD pattern of TAPB-DTT-COF described in the present invention; Figure 5 This is a structural simulation diagram of the TAPB-DTT-COF of the present invention; Figure 6 is a Fourier transform infrared spectrum (FT-IR) diagram of the TAPB-DTT-COF of the present invention; Figure 7 This is a scanning electron microscope image of the TAPB-DTT-COF of the present invention; Figure 8 TEM image of TAPB-DTT-COF of the present invention; Fig. 9 is the UV-visible absorption light of the TAPB-DTT-COF of the present invention; Fig.10 This is the photocurrent response diagram of the TAPB-DTT-COF of the present invention; Fig.11 The chemical reaction formula and catalytic yield of TAPB-DTT-COF catalyzing sulfide of the present invention; Fig.12 The TAPB-DTT-COF catalytic product of the present invention 1 H NMR spectra; Fig.13 The TAPB-DTT-COF catalytic product of the present invention 1 H NMR spectra; Fig.14 The TAPB-DTT-COF catalytic product of the present invention 1 H NMR spectra; Fig.15 The TAPB-DTT-COF catalytic product of the present invention 1 H NMR spectra. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, the embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0024] Example 1 A COF material for improving photogenerated charge separation, the preparation method of which comprises the following steps: (1) Synthesis of monomeric DTT: Take 378.31 mg of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole and 706 mg of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole, 19.8 mg of tri-tert-butylphosphine tetrafluoroborate, add them to a mixture of 1 mL of 2M potassium phosphate aqueous solution and 10 mL of tetrahydrofuran, and then add them to a 100 mL pressure-resistant reaction tube; after nitrogen degassing 3-5 times, add 17.9 mg of Pd2(dba)3 catalyst, heat the reaction system to 80°C for 24 hours, cool to room temperature, extract the reaction solution with ethyl acetate and saturated sodium chloride solution, and then collect the organic phase; after drying with anhydrous magnesium sulfate, remove the solvent in vacuo. The solid was dissolved in a small amount of dichloromethane and purified by silica gel column chromatography (eluent: dichloromethane:ethyl acetate, v / v = 40:1) to obtain a yellow powder monomer (352 mg).

[0025] The yellow powder monomer is subjected to 1 H-NMR analysis and 13 C-NMR analysis, the results are as follows Figure 1 , Figure 2 As shown, it can be concluded from the figure: 1 H-NMR (CDCl3, 400 MHz): δ(ppm) 8.42 (s, J = 4.0 Hz, 2H), 8.39-8.37 (d,J = 8.0 Hz, 2H), 816-8.15 (d, J = 8.0 Hz, 2H), 6.29 (s, J = 4.0 Hz, 2H), 3.89 (s, J = 4.0 Hz, 8H), 1.41 (s, 6H), 0.89 (s, 6H).

[0026] 13 C-NMR (CDCl3, 100 MHz): δ(ppm) 154.11, 153.83, 153.26, 130.99,130.84, 130.41, 129.90, 126.87, 98.09, 77.99, 77.38, 77.06, 76.74, 30.57, 23.09, 21.95.

[0027] (2) Synthesis of COF materials: 27 mg, 0.0427 mmol of the obtained yellow powder monomer, 10 mg, 0.03 mmol of 1,3,5-tri(4-aminophenyl)benzene (TAPB) monomer, and 1.2 mL of o-dichlorobenzene / n-butanol with a volume ratio of 1:1 were added to the reaction vessel, ultrasonically treated for 1 min, and 0.12 mL of a mixed aqueous solution of trifluoroacetic acid (0.6 M) and acetic acid (6 M) was added; ultrasonicated again for 20 seconds, flash-frozen at 77 K in a liquid nitrogen bath, and then degassed by liquid nitrogen freeze-thaw-freeze cycle 3 times under vacuum conditions; vacuum sealed, and finally heated at 120°C for 3 days. After the precipitate was formed, it was collected by suction filtration; it was thoroughly washed with acetone, anhydrous ethanol, tetrahydrofuran and dichloromethane solvents, respectively, and vacuum dried to obtain red powder TAPB-DTT-COF (25 mg, yield 86%).

[0028] The chemical reaction formula of the TAPB-DTT-COF material described in Example 1 is as follows: Figure 3 As shown in , TAPB and DTT are used as monomers for the reaction, and a mixed aqueous solution of o-dichlorobenzene / n-butanol, trifluoroacetic acid and acetic acid is used as the reaction site.

[0029] The following analysis and testing were performed on the obtained TAPB-DTT-COF material: Figure 4 is the PXRD pattern of TAPB-DTT-COF, Figure 5 This is a structural simulation diagram of TAPB-DTT-COF. It can be seen from the figure that the COF stacking model matches the simulation well, and there is a strong diffraction peak at about 2θ of 1.8 degrees, indicating that the COF material has good crystallinity.

[0030] Figure 6 This is the Fourier transform infrared spectrum (FT-IR) of TAPB-DTT-COF. In the figure, in TAPB-DTT-COF, 1103 cm -1 The C=O stretching vibration peak and TAPB (3354 cm -1 、3433 cm -1 The NH stretching vibration peak of ) disappeared after the reaction, while two new C=N (1670 cm -1 ) bonds, indicating the successful synthesis of the COF material.

[0031] Figure 7 , Figure 8 The scanning electron microscope and TEM images of TAPB-DTT-COF are shown respectively. It can be seen that the molecules of TAPB-DTT-COF material are in a relatively orderly aggregation state at scale.

[0032] Fig. 9The UV-visible absorption spectrum of TAPB-DTT-COF material. It can be seen that the COF material has a wide absorption range and high intensity, indicating that the COF material has good light absorption in the UV-visible region. The introduction of the strong electron-withdrawing group DTT makes the band gap of TAPB-DTT-COF material smaller and the absorption range wider, which shows that the conjugated planar DTT unit has significant advantages.

[0033] Fig.10 This is the photocurrent response diagram of TAPB-DTT-COF material, where the current intensity of TAPB-DTT-COF is as high as 1500nA / cm 3 , indicating that the material has a very good ability to generate photoelectric charges under light.

[0034] Fig.11 The chemical reaction formula and catalytic yield diagram of TAPB-DTT-COF material catalyzing various sulfides with electron-rich and electron-deficient substituents. As can be seen from the figure, the catalytic yield is very high, up to nearly 90%, and the COF material has good universality.

[0035] The COF material was used to photocatalyze the reaction of anisole thioether to produce sulfoxide: 0.3 mmol anisole thioether, 10 mg COF material and 3 mL solvent ethanol were mixed in a quartz tube, and then under an oxygen atmosphere, a light power density of 1800 W / m 2 The photocatalytic experiment was carried out under 10W blue LED light irradiation, and the wavelength of LED emission was 460nm. The reaction process was monitored by thin layer chromatography (TLC) and 1H-NMR analysis. The yield of sulfoxide produced by photocatalytic anisyl thioether is shown in Fig.11 As shown, product 1a: p-methoxyanisole; 1b: p-fluoroanisole; 1c: p-chloroanisole; 1d: 2-(methylthio)naphthalene, product 2a: dimethyl sulfoxide; 2b: p-methoxysulfoxide; 2c: p-fluorosulfoxide; 2d: p-chlorosulfoxide).

[0036] The results show that the COF material of the present invention can realize the photocatalysis of sulfides and has good selective catalytic performance of sulfides. Fig.12 This is the 1H NMR spectrum of the product obtained by catalyzing anisyl thioether with TAPB-DTT-COF material.

[0037] Fig.13 This is the 1H NMR spectrum of the product obtained by the catalytic reaction of p-methoxyanisole with TAPB-DTT-COF material.

[0038] Fig.14 This is the 1H NMR spectrum of the product obtained by the catalysis of p-fluoroanisyl thioether by TAPB-DTT-COF material.

[0039] Fig.15 This is the 1H NMR spectrum of the product obtained by the catalysis of p-chloroanisyl thioether by TAPB-DTT-COF material.

[0040] Example 2 A COF material for improving photogenerated charge separation, the preparation method of which comprises the following steps: (1) Synthesis of monomeric DTT: Take 0.5977 g of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole and 1.1154 g of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole, control the molar ratio at 1:2.1, 31.3 g of tri-tert-butylphosphine tetrafluoroborate, mix and add potassium phosphate aqueous solution (1 mL, 2M) and 10 mL of tetrahydrofuran solution.

[0041] 28.2 mg Pd2(dba)3 (catalyst) was added, and the reaction system was heated to 85°C for 25 h and then cooled to room temperature after nitrogen degassing for 3-5 times. The reaction solution was extracted with ethyl acetate and saturated sodium chloride solution, and the organic phase was collected. After drying with anhydrous magnesium sulfate, the solvent was removed in vacuo. The solid was dissolved in a small amount of dichloromethane, and the crude product was purified by silica gel chromatography. The eluent of the silica gel chromatography consisted of dichloromethane and ethyl acetate in a volume ratio of 50:1. 451.7 mg of yellow powder monomer was obtained by silica gel column chromatography.

[0042] (2) Synthesis of COF materials: 7,7''-bis(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT, 26 mg, 0.0411 mmol), 1,3,5-tri(4-aminophenyl)benzene (TAPB, 10 mg, 0.03 mmol) and o-dichlorobenzene / n-butanol (1:1 v / v, 1.0 mL) were added to a 10 mL glass tube. After the mixture was sonicated for 1 min, 0.1 mL of a mixed aqueous solution of trifluoroacetic acid (0.6 M) and acetic acid (6 M) was added. After the mixture was sonicated again for 20 seconds, the tube was flash frozen at 77 K using a liquid nitrogen bath, degassed using three freeze pump-thaw cycles, vacuum sealed, and then heated at 125 °C for 4 days. A red precipitate was formed, which was collected by suction filtration and washed thoroughly with acetone, anhydrous ethanol, tetrahydrofuran and dichloromethane, respectively. The collected sample was dried under vacuum at 120°C for 24 hours to obtain a red powder (24 mg, 83% yield).

[0043] Example 3 A COF material for improving photogenerated charge separation, the preparation method of which comprises the following steps: (1) Synthesis of monomeric DTT: Take 0.498 g of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole and 975.3 mg of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole, 41.77 mg of tri-tert-butylphosphine tetrafluoroborate, add (1 mL, 2 mol) potassium phosphate and 10 mL of tetrahydrofuran solution and then add to the container.

[0044] 37.67 mg Pd2(dba)3 (catalyst) was added, and the reaction system was heated to 90°C for 26 h and then cooled to room temperature. The reaction solution was extracted with ethyl acetate and saturated sodium chloride solution, and the organic phase was collected. After drying with anhydrous magnesium sulfate, the solvent was removed in vacuo. The solid was dissolved in a small amount of dichloromethane, and the crude product was purified by silica gel chromatography. The eluent of the silica gel chromatography consisted of dichloromethane and ethyl acetate in a volume ratio of 40:1. 300.5 mg of yellow powder monomer was obtained by silica gel column chromatography.

[0045] (2) Synthesis of COF materials: 7,7''-bis(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole (DTT, 26.5 mg, 0.0419 mmol), 1,3,5-tri(4-aminophenyl)benzene (TAPB, 10 mg, 0.03 mmol) and o-dichlorobenzene / n-butanol (1:1 v / v, 1.0 mL) were added to a 10 mL glass tube. After the mixture was sonicated for 1 min, 0.1 mL of a mixed aqueous solution of trifluoroacetic acid (0.6 M) and acetic acid (6 M) was added. After the mixture was sonicated again for 20 seconds, the tube was flash-frozen at 77 K using a liquid nitrogen bath, degassed using three freeze pump-thaw cycles, sealed under vacuum, and then heated at 130 °C for 3.5 days. A red precipitate was formed, which was collected by suction filtration and washed thoroughly with acetone, anhydrous ethanol, tetrahydrofuran and dichloromethane, respectively. The collected sample was dried under vacuum at 120 °C for 24 h to obtain a red powder (25 mg, 90% yield).

Claims

1. A COF material for improving photogenerated charge separation, characterized in that: It is a TAPB-DTT-COF material, and its structural formula is shown in Formula I: Formula Ⅰ.

2. The method for preparing a COF material for improving photogenerated charge separation according to claim 1, characterized in that: The following steps are involved: (1) The synthesis of 7,7''-bis(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole is shown in Formula II: Formula II; Take 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole, 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole, tri-tert-butylphosphine tetrafluoroborate, potassium phosphate aqueous solution and tetrahydrofuran, add them into a pressure-resistant reaction tube and mix well; degas with nitrogen, and then add Pd2(dba)3; heat the reaction and then cool to room temperature, and post-treat to obtain a yellow powder 7,7''-di(5,5-dimethyl-1,3-dioxo-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole; (2) COF material synthesis: 7,7''-di(5,5-dimethyl-1,3-dioxy-2-alkyl)-4,4':7',4''-terbenzo[c][1,2,5]thiadiazole DTT, 1,3,5-tri(4-aminophenyl)benzene TAPB and o-dichlorobenzene / n-butanol in a volume ratio of 1:1 are mixed and ultrasonically treated, and then a mixed aqueous solution of trifluoroacetic acid and acetic acid is added; ultrasonication is performed again, and then flash freezing is performed in a liquid nitrogen bath, and then degassing is performed through three freeze-thaw-freeze cycles, vacuum sealing, and finally heating for reaction; after filtering, washing, and drying, the COF material red powder is obtained.

3. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: In the step (1), the amount of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole is 378.31-597.7 mg, the amount of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole is 0.706-1.1154 g, the concentration of the potassium phosphate aqueous solution is 2 mol / L; the amount of tri-tert-butylphosphine tetrafluoroborate is 19.8-41.77 mg, and the amount of the catalyst Pd2(dba)3 in the step (1) is 17.9-37.67 mg.

4. The method for preparing a COF material for improving photogenerated charge separation according to claim 3, characterized in that: In the step (1), the amount of 1,4-diphenylboronic acid pinacol ester benzo[c][1,2,5]thiadiazole is 378.31 mg; the amount of 4-bromo-7-(5,5-dimethyl-1,3-dioxo-2-alkyl)benzo[c][1,2,5]thiadiazole is 0.706 g; and the amount of tri-tert-butylphosphine tetrafluoroborate is 19.8 mg.

5. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: The heating temperature of step (1) is 80-90° C.; the heating time of step (1) is 24-26 h; the post-treatment in step (1) is: extracting the reaction solution with ethyl acetate and saturated sodium chloride solution, then collecting the organic phase, drying it over anhydrous magnesium sulfate, and removing the solvent in vacuo; dissolving the obtained solid in dichloromethane, and purifying it through silica gel column chromatography to obtain a yellow powder monomer.

6. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: In the step (2), the mass ratio of DTT monomer to 1,3,5-tris(4-aminophenyl)benzene TAPB monomer is (2.6-2.7):

1.

7. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: In the step (2), the ultrasonic treatment time is 1 min, the concentration of trifluoroacetic acid in the mixed aqueous solution of trifluoroacetic acid and acetic acid is 0.6 M, and the concentration of acetic acid is 6 M; the temperature of the liquid nitrogen bath is 77 K.

8. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: In the step (2), the heating reaction temperature is 120°C-130°C, and the heating time is 3-4 days.

9. The method for preparing a COF material for improving photogenerated charge separation according to claim 2, characterized in that: In the step (2), the washing is performed using tetrahydrofuran, dichloromethane, acetone and anhydrous ethanol respectively; and the drying is performed by vacuum drying at 120° C. for 24 hours.

10. Use of the COF material for improving photogenerated charge separation according to claim 1 or the COF material for improving photogenerated charge separation prepared by the preparation method according to any one of claims 2 to 9 in photocatalytic production of sulfoxide from anisyl thioether.

Images