Preparation method and application of TAPT-EFIB-20 photocatalyst

Abstract

The invention belongs to the technical field of photocatalysis, and particularly relates to a preparation method and application of a TAPT-EFIB-20 photocatalyst. The catalyst is prepared by taking 2, 4, 6-tri (4-aminophenyl)-1, 3, 5-triazine, terephthalaldehyde and 1-ethyl-3-(4-formyl benzyl)-4, 5-dihydro-1H-imidazole-3-bromide as reaction monomers through a one-step solvothermal method. The TAPT-EFIB-20 photocatalyst has a strong electron-deficient unit due to introduction of ion groups, exciton binding energy is reduced, a strong intermolecular built-in electric field is formed, oriented distribution of electrons is promoted, and meanwhile, interaction between orbits enables the TAPT-EFIB-20 photocatalyst to have higher adsorption capacity on oxygen, so that the generation efficiency of a total reaction of hydrogen peroxide is improved, and the total reaction efficiency of hydrogen peroxide is improved. The method has important application value in hydrogen peroxide generation through photocatalytic reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalysis, and specifically relates to a preparation method and application of a TAPT-EFIB-20 photocatalyst. Background Art

[0002] Hydrogen peroxide is an important chemical widely used in disinfection, bleaching, mining and metallurgy, sterilization and disinfection. In traditional industrial production, hydrogen peroxide is often synthesized by the anthraquinone method, in addition to alcohol oxidation, electrochemical method, and direct hydrogen-oxygen synthesis method. Currently, 95% of the world's total production still comes from the anthraquinone method. Although this method is mature and efficient, it is often accompanied by problems such as high energy consumption and difficulty in product separation and transfer. Photocatalytic technology provides a potential alternative strategy that is more environmentally friendly and economical.

[0003] As a new type of structurally ordered porous crystalline material with covalently linked repeating nodes and linking groups, covalent organic frameworks have unique advantages in the field of photocatalytic hydrogen peroxide generation due to their high specific surface area, adjustable inner surface, adjustable pore size, good sustainability, and high stability compared with materials such as metal oxides, metal sulfides, and graphite carbon nitride. However, most of them require the addition of sacrificial agents or metals under visible light irradiation to achieve a relatively considerable product generation effect. The introduction of these substances will result in, for example, the COF-JLU52 studied by Zhang et al. (Angew. Chem. Int. Ed. 63 (2024) e202411546) showed 7624.7 μmol g -1 h -1 Yang et al. (Chem. Eng. J. 449 (2022) 137802) pointed out that the introduction of Pt single metal site into covalent organic framework can significantly improve the 2e - The promotion effect of ORR; Zhang et al. (J. Mater. Sci. Technol, 2023, 166, 241–249) prepared an S-type heterojunction with ethanol as a sacrificial agent to achieve 7624.7 μmol g -1 h -1 The rate at which hydrogen peroxide is generated.

[0004] Defect engineering is a method that manipulates defect composition and local environment while considering the overall structural integrity. It is difficult to avoid defects caused by factors such as stacking obstacles or dislocations during the crystallization of covalent organic frameworks. Currently, there are still few studies on applying defect engineering to covalent organic frameworks. The appearance of defects can better anchor reactive molecules in the host-guest units, helping to adsorb and activate reactive molecules. However, the introduction of excessive defects will affect the stability of the COF structure, and different degrees of collapse will occur. How to appropriately make defects play a positive role in the structure-activity relationship and the exposure of active sites within a certain range is the focus we need to pay attention to currently. Triazine-based covalent organic frameworks have become one of the candidate materials for incorporating defects to improve COF performance due to their strong aromatic bonds, extended π-conjugated systems, and nitrogen-rich sites. There are no reports on such research. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a metal-ion-free COF that is used for the generation of hydrogen peroxide without the participation of sacrificial agents. The present invention precisely controls the content of defects in the COF by regulating the proportion of ionic groups introduced into the COF, making the electrons show an asymmetric distribution inside the framework, adjusting its local electronic environment, preparing the TAPT-EFIB-20 photocatalyst, and applying it to efficiently generate hydrogen peroxide from oxygen and water.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] The present invention provides a preparation method of a TAPT-EFIB-20 photocatalyst, using 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, terephthalaldehyde, and 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide as reaction raw materials, and obtaining the TAPT-EFIB-20 photocatalyst through a one-step solvothermal method. Among them, the structural formula of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine is as follows:

[0008]

[0009] The structural formula of terephthalaldehyde is as follows:

[0010]

[0011] The structural formula of 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide is as follows:

[0012]

[0013] In the above technical solution, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, terephthalaldehyde, and 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide synthesized by an organic method are used as reaction monomers, and a covalent organic framework material that maintains a certain integrity of the overall structure while introducing appropriate defects to improve its performance is formed through the Knoevenagel condensation reaction.

[0014] Preferably, the specific steps are as follows:

[0015] (1) Place 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, terephthalaldehyde, and 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide in a glass tube, add a mixed solution of dioxane / n-butanol / acetic acid, and mix well by ultrasonic.

[0016] (2) Remove the air in the glass tube through an oil pump in a liquid nitrogen bath, and perform a freeze-pump-thaw cycle to seal the reaction system. After the glass tube returns to room temperature, place it in an oven for reaction.

[0017] (3) After the reaction is completed, take out the glass tube, let it stand until its temperature drops to room temperature, filter, wash, and dry the reaction product to obtain the TAPT-EFIB-20 photocatalyst.

[0018] Preferably, in step (1), the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide to terephthalaldehyde is 2:0.3 - 1.2:1.8 - 2.7, and the glass tube is a Pyrex tube or a Schlenk tube.

[0019] Preferably, in the mixed solution of dioxane / n-butanol / acetic acid in step (1), the volume ratio of dioxane, n-butanol to acetic acid is 7:3:1, and the concentration of acetic acid is 3 - 8M.

[0020] Preferably, in step (2), the reaction temperature is 100 - 150 °C and the time is 3 - 5 days.

[0021] Preferably, in step (3), the solvents used for washing are methanol and absolute ethanol, and the drying temperature is 60 - 80 °C and the time is 12h.

[0022] Preferably, in the step (1), 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide is synthesized via an organic reaction, and the synthesis steps are as follows: p-bromomethylbenzaldehyde and 1-ethylimidazole are mixed in a molar ratio of 1:3, and then acetonitrile is added. The mixture is refluxed at 81-86 °C for 36-48 h. After the reaction, the solvent is removed by rotary evaporation, and then ethyl acetate is added for reflux purification to obtain an oily substance of 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide.

[0023] The present invention also provides a TAPT-EFIB-20 photocatalyst prepared by the above-described preparation method.

[0024] The present invention also provides an application of the above-described TAPT-EFIB-20 photocatalyst in the photocatalytic reaction for generating hydrogen peroxide.

[0025] Preferably, the atmosphere of the photocatalytic reaction is a saturated atmosphere of oxygen, air or argon.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The strong polarization effect of TAPT-EFIB-20 in the present invention offsets the steric barrier effect generated after the introduction of ionic groups, regulates the local electron distribution environment, an asymmetric electron distribution unit appears, reduces the exciton binding energy, and accelerates the reaction of photocatalytic hydrogen peroxide generation.

[0028] (2) TAPT-EFIB-20 in the present invention has a small water contact angle and strong hydrophilicity, and can be better dispersed in an aqueous system.

[0029] (3) The new hybrid orbitals formed by the strong electron-deficient units of TAPT-EFIB-20 in the present invention can establish a stronger interaction with the π orbitals of oxygen, and obtain a faster radical accumulation ability.

[0030] (4) The formation of strong reduction centers in TAPT-EFIB-20 of the present invention is beneficial to exposing more active available sites for oxidation reactions and reduction reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the synthesis of the TAPT-EFIB-20 photocatalyst of the present invention;

[0032] Figure 2 It is an infrared spectrum diagram of Example 1;

[0033] Figure 3 It is a Mott-Schottky diagram of Example 2;

[0034] Figure 4 The energy band structure diagram of Example 2;

[0035] Figure 5 The electrochemical impedance diagram of Example 3;

[0036] Figure 6 The contact angle diagram of Example 4;

[0037] Figure 7 The stability test diagram of Example 4;

[0038] Figure 8 The liquid ultraviolet diagram of hydrogen peroxide concentration - time dependence of Example 5;

[0039] Figure 9 The photocatalytic hydrogen peroxide generation diagram of Example 5;

[0040] Figure 10 The apparent quantum yield diagram at 400 nm of Example 5;

[0041] Figure 11 The SCC diagram of Example 5. Detailed implementation manners

[0042] For the convenience of understanding the present invention, the present invention will be described more comprehensively below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0043] As Figure 1 shown, the present invention synthesizes a metal - free ionic catalyst with a specific defect content by a one - step method. Using a determined monomer, a condensation reaction is carried out via a solvothermal method to obtain a TAPT - EFIB - 20 photocatalyst with an asymmetric electron distribution unit. Since the introduced ionic groups can improve the electron distribution in the framework, regions rich in holes and electrons appear, so that while maintaining a certain crystallinity, the polarity plays a stronger role to form a strong built - in electric field and reduce the exciton binding energy.

[0044] Example 1

[0045] As Figure 1 shown, the preparation method of the TAPT - EFIB - 20 photocatalyst in this example includes the following steps:

[0046] (1) Weigh 10 mmol of 4-bromomethylbenzaldehyde and 30 mmol of 1-ethylimidazole into a three-necked flask; then add 100 mL of acetonitrile, and the mixture is refluxed at 86 °C for 36 h; after the reaction, the solution is rotary-evaporated to remove a large amount of solvent, and ethyl acetate is added for reflux purification to obtain the oily substance 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide monomer;

[0047] (2) Put 0.08 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 0.024 mmol of 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazole-3-bromide and 0.096 mmol of terephthalaldehyde into a Pyrex tube or a Schlenk tube, add 1.1 mL of a mixed solution of dioxane / n-butanol / acetic acid with a volume ratio of 7:3:1 (acetic acid concentration is 6 M), and ultrasonically mix the solute and the solvent;

[0048] (3) In a liquid nitrogen bath, pump out the air in the glass tube through an oil pump, perform a freeze-pump-thaw cycle to seal the reaction system, and after the glass tube returns to room temperature, place it in an oven and react at 150 °C for 4 days;

[0049] (4) After the reaction is completed, take out the glass tube, let it stand until the temperature drops to room temperature, filter off the liquid, and wash the crude product with methanol and absolute ethanol as solvents respectively;

[0050] (5) Dry the product after washing to remove impurities in a vacuum drying oven at 70 °C for 12 h to obtain the TAPT-EFIB-20 photocatalyst.

[0051] The prepared TAPT-EFIB-20 photocatalyst was subjected to ordinary infrared testing. The experimental results are shown in Figure 2 , and a stretching vibration peak of C=N appeared at 1621 cm -1 , while the peaks at 1699 cm -1 attributed to the C=O of the monomer and the peaks at 3205 and 3500 cm -1 attributed to the N-H bond weakened or even disappeared, and these results confirmed the successful condensation of the monomer.

[0052] Example 2

[0053] The preparation steps are the same as those in Example 1, except that: in step (2), the acetic acid concentration is 8 M; in step (3), after the glass tube returns to room temperature, place it in an oven and react at 120 °C for 4 days.

[0054] The prepared TAPT-EFIB-20 photocatalyst was subjected to Mott-Schottky testing. The experimental results are shown in Figure 3, it was found that the flat-band potential of TAPT-EFIB-20 was -0.74 V relative to Ag / AgCl. This material is an n-type material, and its conduction-band potential can be calculated. Then, the energy-band structure diagram can be drawn by combining the band-gap value. The results are shown in Figure 4 , indicating that TAPT-EFIB-20 has appropriate energy-band values to simultaneously complete the ORR and WOR reactions.

[0055] Example 3

[0056] The preparation steps are the same as those in Example 1, except that: after the glass tube returns to room temperature in step (3), it is placed in an oven at 100 °C for reaction for 4 days.

[0057] The prepared TAPT-EFIB-20 photocatalyst was tested by electrochemical impedance spectroscopy. The experimental results are shown in Figure 5 , indicating that TAPT-EFIB-20 has a low interfacial charge-transfer internal resistance. The introduction of ionic groups improves the conductivity of the material, confirming its excellent electrical properties.

[0058] Example 4

[0059] The preparation steps are the same as those in Example 1, except that: the acetic acid concentration in step (2) is 8 M; after the glass tube returns to room temperature in step (3), it is placed in an oven at 150 °C for reaction for 3 days.

[0060] The prepared TAPT-EFIB-20 photocatalyst was tested for contact angle. The experimental results are shown in Figure 6 , indicating that TAPT-EFIB-20 has good hydrophilicity and can be evenly dispersed in water, so that hydrogen peroxide can be well generated in the aqueous system. Then, its stability was tested. The experimental results are shown in Figure 7 , after six tests lasting up to 6 h, the hydrogen peroxide generation rate showed an almost negligible decrease, indicating that the material has a stable structure and sustainable durability.

[0061] Example 5:

[0062] The preparation steps are the same as those in Example 1, except that: after the glass tube returns to room temperature in step (3), it is placed in an oven at 120 °C for reaction for 5 days.

[0063] The prepared TAPT-EFIB-20 photocatalyst was subjected to a photocatalytic hydrogen peroxide generation reaction performance test experiment, specifically including: adding 5 mg of the catalyst into 12 mL of deionized water solution, ultrasonically dispersing it well, using a 300W xenon lamp light source to irradiate through a filter to retain the range of λ≥420nm, and before irradiation, stirring the mixed solution in an oxygen-saturated atmosphere under dark conditions for 30 minutes to achieve adsorption and desorption equilibrium between the catalyst and water molecules and oxygen molecules; then using a light source to carry out a photocatalytic reaction; using a syringe to take samples at equidistant time intervals, filtering with a 0.22μm water filter element, mixing with a color developer, standing for 45 minutes, and then analyzing the amount of hydrogen peroxide generated during the catalytic reaction by a UV-visible spectrophotometer. Figure 8 , 9 It shows that TAPT-EFIB-20 has reached adsorption equilibrium under dark conditions and has a very impressive hydrogen peroxide generation rate in an oxygen-saturated atmosphere, reaching 13871 μmol g in 100 min. cat -1 The hydrogen peroxide yield.

[0064] The prepared TAPT-EFIB-20 photocatalyst was subjected to AQY and SCC experiments, specifically including: using 15 mg and 20 mg of the catalyst for the experiment, respectively, using a 300 W xenon lamp equipped with different cut-off wavelength bandpass filters (400, 420, 450, 500, 550 nm) and a 100 mW / cm 2 The simulated sunlight xenon lamp was used as the light source, and the 2 and 3.14cm 2 The hydrogen peroxide experiment was carried out under the irradiation area of ​​the catalyst, supplemented by UV-visible absorption spectroscopy, to further verify the photocatalytic hydrogen peroxide generation effect of the catalyst. The experimental results are shown in Figure 10 , 11 , indicating that TAPT-EFIB-20 has a high AQY yield and good utilization of visible light.

[0065] The above description is only for better explaining the embodiments of the present invention, and is not intended to limit the present invention. Any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A preparation method of a TAPT-EFIB-20 photocatalyst, characterized in that, Using 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, terephthalaldehyde, and 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide as reaction raw materials, the TAPT-EFIB-20 photocatalyst was obtained via a one-step solvothermal method.

2. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, characterized in that, The specific steps are as follows: (1) Place 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, terephthalaldehyde, and 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide in a glass tube, add a mixed solution of dioxane / n-butanol / acetic acid, and mix well by ultrasound. (2) Remove the air in the glass tube through an oil pump in a liquid nitrogen bath, perform a freeze-pump-thaw cycle to seal the reaction system, and place the glass tube in an oven for reaction after it warms up. (3) After the reaction, take out the glass tube, let it stand until the temperature drops to room temperature, filter, wash, and dry the reaction product to obtain the TAPT-EFIB-20 photocatalyst.

3. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, characterized in that, In step (1), the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide to terephthalaldehyde is 2:0.3 - 1.2:1.8 - 2.7, and the glass tube is a Pyrex tube or a Schlenk tube.

4. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, characterized in that, In the mixed solution of dioxane / n-butanol / acetic acid in step (1), the volume ratio of dioxane, n-butanol, and acetic acid is 7:3:1, and the concentration of acetic acid is 3 - 8 M.

5. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, wherein In step (2), the reaction temperature is 100 - 150 °C, and the reaction time is 3 - 5 days.

6. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, characterized in that, In step (3), the solvents used for washing are methanol and absolute ethanol, the drying temperature is 60 - 80 °C, and the drying time is 12 h.

7. The preparation method of a TAPT-EFIB-20 photocatalyst according to claim 1, characterized in that, In step (1), 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide is synthesized via an organic reaction. The synthesis steps are as follows: Mix p-bromomethylbenzaldehyde and 1-ethylimidazole in a molar ratio of 1:3, add acetonitrile, reflux at 81 - 86 °C for 36 - 48 h, remove the solvent by rotary evaporation from the reaction solution, and then add ethyl acetate for reflux purification to obtain the oily substance 1-ethyl-3-(4-formylbenzyl)-4,5-dihydro-1H-imidazol-3-bromide.

8. The TAPT-EFIB-20 photocatalyst prepared by the preparation method according to any one of claims 1 - 7.

9. The application of the TAPT-EFIB-20 photocatalyst according to claim 8 in the photocatalytic reaction for generating hydrogen peroxide.

10. Use of the TAPT-EFIB-20 photocatalyst according to claim 9, characterized in that, The atmosphere of the photocatalytic reaction is a saturated atmosphere of oxygen, air, or argon.

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