Preparation method and application of a kind of photocatalyst based on tetraphenyl ethane organic framework

Abstract

The application discloses a preparation method and application of a photocatalyst based on a tetraphenyl ethylene organic framework, and belongs to the photocatalyst field. In the application, a tetraphenyl ethylene organic framework TPE-B is used as a parent unit, and a photocatalyst for producing H2O2 is prepared by using a proper crosslinking agent through a Friedel-Crafts alkylation reaction. The photocatalyst prepared in the application has excellent photocatalytic H2O2 production capacity, and the photocatalyst is used to photocatalytically prepare H2O2, and the raw materials required for the photocatalytic preparation are only water and oxygen, the raw materials are simple and easy to obtain, the production cost is low, and the photocatalyst has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the preparation and application of a photocatalyst, and more particularly to a method for preparing and applying a photocatalyst based on a tetraphenylethylene organic framework. Background Technology

[0002] Tetraphenylene (TPE)-based organic frameworks exhibit significant advantages in the photocatalytic production of hydrogen peroxide (H₂O₂). Their unique aggregation-induced emission (AIE) properties enable them to demonstrate excellent optical performance in the aggregated state, significantly improving photocatalytic efficiency. A broad light absorption range and tunable electronic structure further enhance the separation efficiency of photogenerated electrons and holes, thereby increasing the yield of hydrogen peroxide. Simultaneously, TPE organic frameworks possess excellent chemical and thermal stability, maintaining catalytic activity over long periods under reaction conditions. Their molecular structure is easily functionalized, and catalytic performance can be further optimized by introducing different functional groups. Furthermore, this material is typically based on metal-free organic compositions, making it environmentally friendly and non-toxic, demonstrating immense application potential.

[0003] Hydrogen peroxide (H2O2) is a colorless and transparent liquid with strong oxidizing and bleaching properties, widely used in medical disinfection, industrial bleaching, oxygen production, wastewater treatment, and food preservation. Currently, there are many methods for producing H2O2, such as the anthraquinone process, the direct hydrogen-oxygen synthesis method (DSHP), and electrolysis, but most of these methods suffer from drawbacks such as high energy consumption, high investment, and complex processes. Photocatalytic hydrogen peroxide production, however, offers advantages such as green and sustainable synthesis, high selectivity, high quantum efficiency, and high photochemical conversion efficiency.

[0004] Currently, there are no reports on the application of tetraphenylethylene organic frameworks in the photocatalytic preparation of H2O2. How to prepare a catalyst based on tetraphenylethylene organic frameworks that can efficiently produce H2O2 by photocatalysis has become an urgent technical problem to be solved. Summary of the Invention

[0005] Objective of this invention: The objective of this invention is to provide a method for preparing a photocatalyst based on a tetraphenylethylene organic framework, thus solving the problem of how to prepare photocatalysts. Another objective of this invention is to propose the application of a photocatalyst based on a tetraphenylethylene organic framework in the photocatalytic production of H2O2, thereby solving the problem of how to efficiently produce H2O2 through photocatalysis.

[0006] Technical solution: The present invention discloses a method for preparing a photocatalyst based on a tetraphenylethylene organic framework, characterized by comprising the following steps:

[0007]

[0008] Where X is a halogen.

[0009] This invention uses tetraphenylethylene (TPE-B) organic framework as the parent unit and employs a suitable crosslinking agent to prepare a photocatalyst for H2O2 production via a Friedel-Crafts alkylation reaction. The crosslinking sites in the polymerization product can be between the phenyl groups of different TPE-B molecules or between pyridine groups.

[0010] Preferably, the halogen is Cl or Br.

[0011] Preferably, the catalyst is a Lewis acid catalyst.

[0012] More preferably, the Lewis acid catalyst is aluminum chloride or ferric chloride.

[0013] Preferably, the solvent is at least one selected from toluene, dichloromethane, N,N-dimethylformamide, tetrahydrofuran, 1,2-dichloroethane, 1,4-dioxane, trichloromethane, and dimethyl sulfoxide.

[0014] Preferably, the inert atmosphere is a nitrogen or helium atmosphere, and the heating conditions are a reaction at 75-105°C for 3-6 days.

[0015] Preferably, the molar ratio of compound II to compound III is 1:2-6.

[0016] In some embodiments, the following product purification step is further included after completion:

[0017] The reaction product was filtered to obtain a solid crude product. The crude product was washed with methanol and hydrochloric acid aqueous solution, and then extracted with methanol using a Soxhlet extractor for 2-3 days. After vacuum drying, the photocatalyst was obtained.

[0018] Another aspect of the present invention discloses the application of the photocatalyst prepared by the above-described method in the photocatalytic preparation of hydrogen peroxide.

[0019] The method for photocatalytically preparing hydrogen peroxide using the above-mentioned photocatalyst includes the following steps:

[0020] Under aerobic conditions, the photocatalyst is mixed with water and then continuously irradiated with light to produce H2O2.

[0021] Preferably, the aerobic conditions are in the air environment, and the light conditions are 500-700 mW / cm². 2 Under intense light irradiation, the ratio of the photocatalyst to water is 5-10 mg: 10-30 mL.

[0022] The photocatalyst can be mixed with water by ultrasonic dispersion, with a power of 2000-4500 Hz and a time of 5-10 min.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0024] The photocatalyst prepared in this invention has excellent photocatalytic H2O2 production capability. The only raw materials required for the photocatalytic preparation of H2O2 using this catalyst are water and oxygen. The raw materials are simple and readily available, and the production cost is low. Moreover, the photocatalytic reaction is not sensitive to changes in the acidity or alkalinity of the reaction environment. It can efficiently prepare H2O2 under production conditions with large fluctuations, which can meet the relatively stringent production requirements for industrial applications. Attached Figure Description

[0025] Figure 1 The Fourier transform infrared absorption spectrum of the photocatalyst prepared in this invention;

[0026] Figure 2 The solid ultraviolet-visible absorption spectrum of the photocatalyst prepared in this invention is shown below.

[0027] Figure 3 Impedance diagram of the photocatalyst prepared in this invention;

[0028] Figure 4 The effect of different pH values ​​on the photocatalytic activity of the photocatalyst prepared in this invention;

[0029] Figure 5 This is a graph showing the change in photocatalytic activity of the photocatalyst prepared in this invention as a function of reaction time.

[0030] Figure 6 The experimental results show the degradation of hydrogen peroxide by the photocatalyst prepared in this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0032] Example 1: A method for preparing a photocatalyst is as follows:

[0033]

[0034] Tetra(4-pyridinylphenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (1.09 g, 4.36 mmol), and dichloromethane (100 mL) were added to a 500 mL Shrek tube and thoroughly dissolved and mixed. Then, 1.09 g of aluminum trichloride was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 90 °C and reacted for 6 days, with TLC monitoring. After the reaction was complete, the solid was filtered to obtain the crude product, which was washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-NF, with a yield of 53%. The infrared spectrum of TPE-NF is shown below. Figure 1 As shown.

[0035] Example 2: A method for preparing a photocatalyst is as follows:

[0036] In a 500 mL Shrek tube, tetra(4-pyridinephenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (1.64 g, 6.54 mmol), and 1,2-dichloroethane (100 mL) were added and thoroughly dissolved and mixed. Then, 1.09 g of aluminum trichloride was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 85 °C and reacted for 5 days, with TLC monitoring. After the reaction was complete, the solid was filtered to obtain the crude product, which was washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-NA, in 11% yield.

[0037] Example 3: A method for preparing a photocatalyst is as follows:

[0038] Tetra(4-pyridinylphenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (548 mg, 2.12 mmol), and toluene (100 mL) were added to a 500 mL Shrek tube, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 95 °C and reacted for 4 days, with TLC monitoring. After the reaction was complete, the solid was collected by filtration and washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-NS, in 58% yield. The infrared spectrum of the product is shown below. Figure 1 As shown.

[0039] Example 4: A method for preparing a photocatalyst is as follows:

[0040] In a 500 mL Shrek tube, tetra(4-pyridinephenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (1.64 g, 6.54 mmol), and tetrahydrofuran (100 mL) were added and thoroughly dissolved and mixed. Then, 1.09 g of ferric chloride was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 75 °C and reacted for 6 days, with TLC monitoring. After the reaction was complete, the solid was filtered to obtain the crude product, which was washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-ND, in 50% yield.

[0041] Example 5: A method for preparing a photocatalyst is as follows:

[0042] Tetra(4-pyridinephenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (1.64 g, 6.54 mmol), and 1,4-dioxane (100 mL) were added to a 500 mL Shrek tube and thoroughly dissolved and mixed. Then, 1.09 g of ferric chloride was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 90 °C and reacted for 6 days, with TLC monitoring. After the reaction was complete, the solid was filtered to obtain the crude product, which was washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-NQ, in 34% yield.

[0043] Example 6: A method for preparing a photocatalyst is as follows:

[0044] Tetra(4-pyridinephenyl)ethylene (700 mg, 1.09 mmol), biphenyl dichlorobenzyl (1.64 g, 6.54 mmol), and DMSO (100 mL) were added to a 500 mL Shrek tube and thoroughly dissolved and mixed. Then, 1.09 g of ferric chloride was added, and the reaction was carried out under a nitrogen atmosphere for 30 minutes. The mixture was heated to 105 °C and reacted for 3 days, with TLC monitoring. After the reaction was complete, the solid was filtered to obtain the crude product, which was washed with methanol and hydrochloric acid aqueous solution. Methanol extraction for 2-3 days yielded a pale yellow powder, TPE-NT, in 22% yield.

[0045] The structure of the photocatalyst was confirmed by FT-IR. In the FT-IR spectrum, at 1382 cm⁻¹... -1 and 1644cm -1 The characteristic absorption peaks at these locations correspond to the stretching vibrations of the double bond (-C=C-) and the benzene ring skeleton, respectively; after the introduction of methylene linkages in the crosslinking reaction, two new characteristic absorption peaks appeared in the spectrum: 2705 cm⁻¹ -1 The absorption peak at 1118 cm⁻¹ is attributed to the symmetric stretching vibration of the methylene group, while the peak at 1118 cm⁻¹ is attributed to the symmetric stretching vibration of the methylene group. -1 The absorption peak at that point corresponds to the bending vibration of the methylene group. Figure 1 The appearance of these characteristic peaks not only confirms the successful introduction of methylene groups, but also further confirms the successful preparation of TPE-NF and TPE-NS.

[0046] The light absorption performance and impedance of the photocatalysts prepared in Examples 1 and 3 were tested, and the results are as follows: Figure 2 and 3 As shown. The ultraviolet-visible diffuse reflectance spectrum shows ( Figure 2 TPE-NS exhibits a wider light absorption range, indicating its potential advantage in light-harvesting capabilities. The EIS spectrum shows ( Figure 3 TPE-NF exhibits a smaller EIS radius, demonstrating its superior e — and h + Low composite rate.

[0047] Example 7: Photocatalytic hydrogen peroxide production test

[0048] The photocatalyst TPE-NF (5 mg) prepared in Example 1 was added to 20 mL of pure water at pH 7.0 and sonicated at 3500 Hz for 7 minutes to ensure uniform dispersion. The mixed solution was then slowly poured into a 50 mL specific reactor and subjected to a 300 W xenon lamp (600 mW / cm²) in air. 2Illuminate the solution. Every 10 minutes, take 1.5 mL of the reaction solution, filter it through a 0.22 μm filter membrane to remove catalyst particles, and then add 1 mL of potassium titanium oxalate solution (0.02 M). Finally, measure the absorbance of the solution at 400 nm using a UV spectrophotometer, and calculate that the concentration of hydrogen peroxide in the reaction solution after 60 minutes of reaction is 0.87 mmol / L.

[0049] Example 8: The rest is the same as Example 7, except that:

[0050] The pH of pure water was adjusted to 3, 5, 7, and 9 using hydrochloric acid or NaOH, respectively. Water with different pH values ​​was then mixed with the photocatalyst TPE-NF to produce H₂O₂. The results are shown in Figure 4. Figure 4 This indicates that the photocatalyst prepared by the present invention can stably catalyze the generation of H2O2 over a wide pH range, and the yield of H2O2 is even higher under neutral solution conditions.

[0051] Example 9: The rest is the same as Example 7, except that:

[0052] Add 10 mg of TPE-NF to 20 mL of pure water at pH 7.0, under a light intensity of 500 mW / cm². 2 .

[0053] The concentration of hydrogen peroxide in the reaction solution was calculated to be 0.75 mmol / L after 60 min of reaction.

[0054] Example 10: The rest is the same as Example 7, except that:

[0055] Add 10 mg of TPE-NF to 20 mL of seawater at a light intensity of 700 mW / cm². 2 .

[0056] The concentration of hydrogen peroxide in the reaction solution was calculated to be 0.61 mmol / L after 60 min of reaction.

[0057] Example 11: Everything else is the same as in Example 7, except that:

[0058] TPE-NF (25 mg) was added to 100 mL of pure water at pH 7.0 for reaction. 1.5 mL of the reaction solution was taken every 1 hour to measure the concentration of hydrogen peroxide. The results are as follows: Figure 5 As shown. Figure 5 To further explore the long-term stability and recyclability of the photocatalyst, continuous photocatalytic experiments and multiple cycle tests were conducted. The experimental results showed that the H2O2 formation rate continuously increased in the first 9 hours, then gradually stabilized. Figure 5 This indicates that the photocatalyst exhibits good stability during long-term operation.

[0059] Example 12: The photocatalyst prepared in Example 1 was tested for its degradation effect on hydrogen peroxide. The method is as follows:

[0060] In the experiment of photocatalytic degradation of H2O2, a 300W xenon lamp (Xe lamp) was used to simulate sunlight irradiation. Before the experiment, 5 mg of photocatalyst was uniformly dispersed in 20 mL of 1 M H2O2. Subsequently, at 600 mW / cm², the photocatalyst was... 2 The solution was irradiated under light intensity, and a circulating cooling system was used to maintain a stable temperature and prevent solvent evaporation due to overheating. During the irradiation process, 1.5 mL of the suspension was drawn every 10 minutes, filtered through a syringe with a 0.22 μm filter membrane, and the concentration of H₂O₂ generated was measured using 0.02 M potassium titanium oxalate solution. The results are as follows: Figure 6 As shown, by Figure 6 As can be seen, in the H2O2 decomposition experiment conducted in the N2 atmosphere, the H2O2 concentration of TPE-NF showed a significant increasing trend with the extension of light exposure time. TPE-NF can not only effectively promote the accumulation of H2O2, but also better resist its decomposition.

[0061] Comparative Example 1: Everything else is the same as in Example 1, except that:

[0062] Replace the tetraphenylethylene organic framework with tetraphenylethylene.

[0063] Comparative Example 2: Everything else is the same as in Example 1, except that:

[0064] Replace tetra(4-pyridinylphenyl)ethylene with:

[0065]

[0066] Comparative Example 3: Everything else is the same as in Example 1, except that:

[0067] Replace tetra(4-pyridinephenyl)ethylene with 4-phenylpyridine.

[0068] Comparative Example 4: Everything else is the same as in Example 1, except that:

[0069] Replace tetra(4-pyridinephenyl)ethylene with pyridine.

[0070] Comparative Example 5: Without cross-linking reaction, tetra(4-pyridinephenyl)ethylene was directly used as the photocatalyst sample for subsequent testing.

[0071] The catalyst samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested for their photocatalytic H2O2 production capacity according to the method in Example 7. The reaction time was 12 h, and the results are as follows:

[0072] Table 1. Results of photocatalytic activity tests for different photocatalyst samples.

[0073]

[0074] As shown in Table 1, the sample prepared by crosslinking unsubstituted tetraphenylethylene does not possess the ability to photocatalyze the production of H2O2. Similarly, the sample prepared by reacting 4-phenylpyridine or pyridine molecules alone with biphenyl dichlorobenzyl also lacks the ability to photocatalyze the production of H2O2. These results indicate that the tetraphenylethylene group and its pyridine substituents are essential for the photocatalytic production of H2O2 in this invention. In Comparative Example 2, when the substituents on the tetraphenylethylene group were replaced with phenyl groups, the photocatalytic production of H2O2 decreased significantly, indicating that the tetraphenylethylene group and the pyridine substituents have a synergistic effect, significantly enhancing the catalytic activity of the photocatalyst. Therefore, only by using the tetraphenylethylene organic framework as the parent material and appropriately crosslinking it can the efficient catalytic production of H2O2 using oxygen and water as substrates be achieved. Comparative Example 5 shows that the uncrosslinked tetra(4-pyridinephenyl)ethylene monomer does not possess photocatalytic activity for H2O2 production; it only acquires photocatalytic activity after appropriate crosslinking.

Claims

1. The application of a photocatalyst based on a tetraphenylethylene organic framework in the photocatalytic preparation of hydrogen peroxide, characterized in that, The preparation method of the photocatalyst based on the tetraphenylethylene organic framework includes the following steps: Where X is a halogen; The molar ratio of compound II to compound III is 1:2-4.

2. The application according to claim 1, characterized in that, The halogen is Cl or Br.

3. The application according to claim 1, characterized in that, The catalyst is a Lewis acid catalyst.

4. The application according to claim 3, characterized in that, The Lewis acid catalyst is aluminum chloride or ferric chloride.

5. The application according to claim 1, characterized in that, The solvent is toluene, dichloromethane, N , N - At least one of dimethylformamide, tetrahydrofuran, 1,2-dichloroethane, 1,4-dioxane, chloroform, and dimethyl sulfoxide.

6. The application according to claim 1, characterized in that, The inert atmosphere is nitrogen or helium, and the heating conditions are a reaction at 75-105°C for 3-6 days.

7. The application according to claim 1, characterized in that, Includes the following steps: Under aerobic conditions, the photocatalyst is mixed with water and then continuously irradiated with light to produce H2O2.

8. The application according to claim 7, characterized in that, The aerobic conditions refer to an air environment with a light intensity of 500-700 mW / cm². 2 Under intense light irradiation, the ratio of the photocatalyst to water is 5-10 mg: 10-30 mL.

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