A visible light photocatalyst for in-situ synthesis of hydrogen peroxide and its preparation method and application

Abstract

The invention discloses a visible light photocatalyst for in-situ synthesis of hydrogen peroxide and a preparation method and application thereof, belonging to the technical field of photocatalytic material preparation; the invention adopts a wet impregnation method to impregnate a covalent organic polymer with chloroauric acid so that the chloroauric acid is evenly distributed on the inner surface of the covalent organic polymer, thereby assisting sodium borohydride reduction to obtain gold nanoparticles and loading them on the covalent organic polymer to synthesize a gold-loaded covalent organic polymer (Au / COFs) visible light photocatalyst; the photocatalyst can significantly improve the absorption capacity of visible light, has good visible light photoresponse and excellent photocatalytic performance, and can efficiently reduce oxygen to synthesize hydrogen peroxide in situ under visible light; the photocatalyst can be applied to the environmental field of sustainable development and the field of clean production, sterilizes water bodies by combining with advanced oxidation technology, and the preparation method is simple, the synthesis efficiency is high, meets the actual production needs, and has high practical value and good environmental significance.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalytic material preparation, and specifically relates to a visible light photocatalyst for in-situ synthesis of hydrogen peroxide and a preparation method and application thereof. Background Art

[0002] Disinfection is a necessary step in the water treatment industry to prevent the spread of pathogenic bacteria and related diseases. Although there are many methods to deal with microorganisms in water, some traditional technologies are too complicated, inefficient, and sometimes affected by the environment, and even cause secondary pollution to the environment.

[0003] The use of photocatalytic technology to synthesize hydrogen peroxide in situ and carry out advanced oxidation processes (AOPs) has become a research hotspot in the field of photocatalysis and environmental chemistry. Compared with the traditional anthraquinone process, this process does not use the more dangerous hydrogen (H2) to participate in the reaction. It only uses the abundant oxygen on the earth as a raw material, sunlight as an energy source, and semiconductors as photocatalysts, and the whole process is pollution-free. It abandons the limitation of high energy consumption of traditional photoelectric in situ synthesis of hydrogen peroxide.

[0004] Advanced oxidation technology (AOPs) is one of the most promising technologies for treating industrial wastewater and water disinfection. Its main advantage is that with the participation of hydroxyl radicals, it can effectively remove stubborn components and pathogens in water, and the whole process will not produce secondary waste. 2+ The Fenton reaction, which reacts with hydrogen peroxide to produce hydroxyl radicals, is the main method for water disinfection [Equation (1)]. Divalent iron reacts with hydrogen peroxide to produce hydroxyl radicals, 1 mol of trivalent iron (Fe 3+ ) and 1 mol of hydroxyl groups (OH - ). It is precisely because of the presence of hydroxyl radicals that the Fenton reaction has strong oxidizing properties. Therefore, the application of Fenton technology for water disinfection and degradation of pollutants has broad prospects.

[0005] Fe 2+ +H2O2→Fe 3+ +OH - + OH (1)

[0006] As an emerging porous material, COFs is a type of crystalline porous organic polymer with permanent porosity and highly ordered structure. It has high thermal stability, high surface area, extremely low density and better modifiability. It is mainly composed of a series of light elements such as C, N, H, O, B, etc., and is connected by structural units such as covalent bonds to form a polygonal topological structure with a rich nitrogen atom skeleton and a stable chemical structure. It can provide more sites for oxygen adsorption and in-situ generation of hydrogen peroxide, which is conducive to the photocatalytic reaction. It is a new type of organic photocatalytic material with potential development prospects.

[0007] Literature reports that a covalent organic polymer connected by an imine bond (He, S., Yin, B., Niu, H., Cai, Y., Targeted synthesis of visible-light-driven covalent organic framework photocatalyst via molecular design and precise construction. Applied Catalysis B: Environmental 2018, 239, 147-153.) is a photocatalyst with application potential, but the covalent organic polymer has problems such as narrow light response range and high recombination rate of photogenerated carriers, which restricts its further application in the field of photocatalysis. The introduction of precious metals as co-catalysts can significantly improve the material's absorption capacity for visible light while inhibiting the recombination of photogenerated carriers. Therefore, loading gold nanoparticles on covalent organic polymers can greatly improve their photocatalytic performance.

[0008] The invention with publication number CN104397026A provides a potassium ferrate bactericide for water treatment and a preparation method thereof, but it does not solve the problem of low efficiency of potassium ferrate combining with electrons to generate Fe(IV) and Fe(V) with strong oxidizing ability, cannot fully utilize the oxidizing ability of potassium ferrate, is not suitable for industrial applications, and uses phosphorus trichloride in the production process, which is likely to cause further environmental pollution; the invention with publication number CN104014352A discloses a multi-controllable synthesis method of a BiOCl photocatalyst, which can be used for photocatalytic degradation of pollutants in water, especially carbamazepine drugs, but a large amount of reagents are used in the catalyst preparation process, and the preparation process is relatively complicated and time-consuming, which increases the burden on the environment. Summary of the invention

[0009] The present invention discloses a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, and a preparation method and application thereof. The photocatalyst can significantly improve the absorption capacity of visible light, has good visible light light response and excellent photocatalytic performance, can efficiently reduce oxygen to synthesize hydrogen peroxide in situ under visible light irradiation, sterilizes water bodies by combining advanced oxidation technology, effectively removes stubborn components and pathogenic bacteria in water, and the preparation method is simple, the synthesis efficiency is high, and the photocatalyst has high practical value and good environmental significance.

[0010] The technical solution of the present invention is as follows:

[0011] One of the purposes of the present invention is to provide a method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, wherein a covalent organic polymer is impregnated with chloroauric acid by a wet impregnation method so that the chloroauric acid is evenly distributed on the inner surface of the covalent organic polymer, thereby assisting sodium borohydride reduction to obtain gold nanoparticles and loading them on the covalent organic polymer.

[0012] Furthermore, the preparation method is as follows:

[0013] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine are dissolved in a ternary solvent consisting of mesitylene, 1,4-dioxane, and 3M acetic acid, the mixed solution is sonicated in an ultrasonic machine and nitrogen is introduced, and then the mixed solution is placed in an oven for reaction to form a light yellow precipitate by self-nucleation, and the reaction is naturally cooled to room temperature after completion;

[0014] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying the precipitate in a vacuum oven to obtain a covalent organic polymer;

[0015] S3, placing the covalent organic polymer obtained in S2 in ultrapure water, ultrasonicating it, and then adding chloroauric acid and stirring to mix well;

[0016] S4. Slowly add the sodium borohydride aqueous solution to the solution described in S3 and stir vigorously for 60 minutes. Then place it in an oil bath and continue stirring until the reaction is complete. After the reaction is completed, naturally cool to room temperature, wash with pure water and anhydrous ethanol, and freeze-dry to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0017] Furthermore, the volume ratios of mesitylene, 1,4-dioxane and 3M acetic acid in the ternary solvent in S1 are 5:5:1 respectively, and the amount of the ternary solvent added is 11 mL.

[0018] Furthermore, the mixed solution in S1 is sonicated for 10-20 min, and nitrogen is introduced for 10-20 min.

[0019] Furthermore, the reaction temperature in the oven in S1 is 110-130° C., and the reaction time is 2-4 days.

[0020] Furthermore, the drying temperature in S2 is 110-130° C., and the drying time is 8-12 hours.

[0021] Furthermore, the volume of the sodium borohydride aqueous solution in S4 is 15-25 μL, and the concentration is 0.2-0.4 gmL -1 .

[0022] Furthermore, the S4 is stirred in an oil bath at a temperature of 50-70° C. for 2-4 h.

[0023] A second object of the present invention is to provide a visible light photocatalyst for in-situ synthesis of hydrogen peroxide.

[0024] The third object of the present invention is to provide an application of a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, by utilizing visible light to reduce oxygen to synthesize hydrogen peroxide in situ, and combining it with advanced oxidation technology to sterilize water.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The present invention is the first to introduce gold nanoparticles into a new covalent organic polymer, and develop a new type of photocatalytic material with noble metal elements as the catalyst, which significantly improves the absorption capacity of visible light, achieves a rapid response under visible light, and has good visible light response and photocatalytic performance. In addition, the H2O2 production performance test was carried out under the premise of the same metal loading amount. Compared with other metals, the loading performance of Au is the most outstanding, and its H2O2 production can reach about 1932μmol g -1 h -1 .

[0027] 2. The visible light photocatalyst provided by the present invention can efficiently utilize visible light to reduce oxygen to synthesize hydrogen peroxide in situ, and combine with advanced oxidation technology to produce more hydroxyl free radicals, making the Fenton reaction highly oxidizing, thereby effectively removing stubborn components and pathogens in water, and no secondary waste is generated in the whole process.

[0028] 3. The present invention adopts a chemical reduction method and uses sodium borohydride as a reducing agent to prepare gold-loaded covalent organic polymer visible light photocatalyst Au / COFs. Compared with other traditional methods such as photoreduction and high-temperature calcination, the sodium borohydride reduction method can obtain a composite material with a high metal loading in a very short time.

[0029] 4. The preparation method provided by the present invention overcomes the time-consuming and labor-intensive problems of traditional preparation methods. The preparation method is simple, easy to operate, controllable in process, easy to implement, does not require high temperature and high pressure preparation conditions, has a fast synthesis rate, high efficiency, and meets environmentally friendly requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a transmission electron microscope image of the visible light photocatalyst of Example 2 of the present invention;

[0031] Figure 2 It is a Fourier transform infrared spectrum of the covalent organic polymer and the visible light photocatalyst of Example 2 of the present invention;

[0032] Figure 3 This is a diagram showing the effect of in-situ synthesis of hydrogen peroxide by a covalent organic polymer and a visible light photocatalyst in Example 2 of the present invention;

[0033] Figure 4 This is a diagram showing the bactericidal effect of a covalent organic polymer and the visible light photocatalyst of Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments. The given embodiments are only for illustrating the present invention, rather than for limiting the scope of the present invention.

[0035] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources;

[0036] The quantitative tests in the following examples were repeated three times, and the results were averaged.

[0037] The experimental methods in the following embodiments are conventional methods unless otherwise specified.

[0038] Example 1

[0039] This embodiment provides a method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, which specifically comprises the following steps:

[0040] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine were dissolved together in a ternary solvent of mesitylene, 1,4-dioxane, and 3M acetic acid. The volume ratio of the three solvents was 5:5:1, and the total volume of the three solvents was 11 mL. Ultrasonication was performed in an ultrasonic machine for 10 minutes to make it evenly dispersed, and nitrogen was introduced for 10 minutes. Then, the mixed solution was placed in an oven at 110°C for reaction for 2 days to form a light yellow precipitate, and then naturally cooled to room temperature.

[0041] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying it in a vacuum oven at 110° C. for 8 h to obtain a covalent organic polymer;

[0042] S3, placing 100 mg of the covalent organic polymer in 150 mL of ultrapure water and ultrasonicating for 30 min, then adding 0.5 mg of Au chloroauric acid into the aqueous solution and stirring for 30 min to allow the two to fully contact;

[0043] S4, 15 μL 0.2 g mL -1 Sodium borohydride aqueous solution was slowly added to the solution described in S3 and stirred vigorously for 60 minutes, then placed on an oil bath and stirred at 50°C for 2 hours. After cooling to room temperature, it was washed with pure water and anhydrous ethanol, and freeze-dried to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0044] The gold content in the visible light photocatalyst prepared according to the method of Example 1 is 0.5 mg.

[0045] Example 2

[0046] This embodiment provides a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, which specifically includes the following steps:

[0047] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine were dissolved together in a ternary solvent of mesitylene, 1,4-dioxane, and 3M acetic acid. The volume ratio of the three solvents was 5:5:1, and the total volume of the three solvents was 11 mL. Ultrasonication was performed in an ultrasonic machine for 15 minutes to make it evenly dispersed, and nitrogen was introduced for 15 minutes. The mixed solution was then placed in an oven at 120°C for reaction for 3 days to form a light yellow precipitate, and then naturally cooled to room temperature.

[0048] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying it in a vacuum oven at 120° C. for 10 h to obtain a covalent organic polymer;

[0049] S3, placing 100 mg of the covalent organic polymer in 150 mL of ultrapure water and ultrasonicating for 30 min, then adding chloroauric acid with a content of 1 mg Au into the aqueous solution and stirring for 30 min to allow the two to be in full contact;

[0050] S4, 20 μL 0.3 g mL -1Sodium borohydride aqueous solution is slowly added to the solution described in S3 and stirred vigorously for 60 minutes, then placed on an oil bath and stirred at 60°C for 3 hours. After cooling to room temperature, it is washed with pure water and anhydrous ethanol, and freeze-dried to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0051] The gold content in the visible light photocatalyst prepared according to the method of Example 2 is 1 mg.

[0052] Example 3

[0053] This embodiment provides a method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, which specifically comprises the following steps:

[0054] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine were dissolved together in a ternary solvent of mesitylene, 1,4-dioxane, and 3M acetic acid. The volume ratio of the three solvents was 5:5:1, and the total volume of the three solvents was 11 mL. Ultrasonication was performed in an ultrasonic machine for 15 minutes to make it evenly dispersed, and nitrogen was introduced for 15 minutes. The mixed solution was then placed in an oven at 120°C for reaction for 3 days to form a light yellow precipitate, and then naturally cooled to room temperature.

[0055] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying it in a vacuum oven at 120° C. for 10 h to obtain a covalent organic polymer;

[0056] S3, placing 100 mg of the covalent organic polymer in 150 mL of ultrapure water and ultrasonicating for 30 min, then adding chloroauric acid containing 1.5 mg of Au into the aqueous solution and stirring for 30 min to allow the two to be in full contact;

[0057] S4, 20 μL 0.3 g mL -1 Sodium borohydride aqueous solution is slowly added to the solution described in S3 and stirred vigorously for 60 minutes, then placed on an oil bath and stirred at 60°C for 3 hours. After cooling to room temperature, it is washed with pure water and anhydrous ethanol, and freeze-dried to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0058] The gold content in the visible light photocatalyst prepared according to the method of Example 3 is 1.5 mg.

[0059] Example 4

[0060] This embodiment provides a method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, which specifically comprises the following steps:

[0061] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine were dissolved together in a ternary solvent of mesitylene, 1,4-dioxane, and 3M acetic acid. The volume ratio of the three solvents was 5:5:1, and the total volume of the three solvents was 11 mL. Ultrasonication was performed in an ultrasonic machine for 15 minutes to make it evenly dispersed, and nitrogen was introduced for 15 minutes. The mixed solution was then placed in an oven at 120°C for reaction for 3 days to form a light yellow precipitate, and then naturally cooled to room temperature.

[0062] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying it in a vacuum oven at 120° C. for 10 h to obtain a covalent organic polymer;

[0063] S3, placing 100 mg of the covalent organic polymer in 150 mL of ultrapure water and ultrasonicating for 30 min, then adding chloroauric acid with a content of 2 mg Au into the aqueous solution and stirring for 30 min to allow the two to be fully in contact;

[0064] S4, 20 μL 0.3 g mL -1 Sodium borohydride aqueous solution is slowly added to the solution described in S3 and stirred vigorously for 60 minutes, then placed on an oil bath and stirred at 60°C for 3 hours. After cooling to room temperature, it is washed with pure water and anhydrous ethanol, and freeze-dried to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0065] The gold content in the visible light photocatalyst prepared according to the method of Example 4 is 2 mg.

[0066] Example 5

[0067] This embodiment provides a method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, which specifically comprises the following steps:

[0068] S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine were dissolved together in a ternary solvent of mesitylene, 1,4-dioxane, and 3M acetic acid. The volume ratio of the three solvents was 5:5:1, and the total volume of the three solvents was 11 mL. Ultrasonication was performed in an ultrasonic machine for 20 minutes to make it evenly dispersed, and nitrogen was introduced for 20 minutes. The mixed solution was then placed in an oven at 130°C for reaction for 4 days to form a light yellow precipitate, and then naturally cooled to room temperature.

[0069] S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying it in a vacuum oven at 130° C. for 12 h to obtain a covalent organic polymer;

[0070] S3, placing 100 mg of the covalent organic polymer in 150 mL of ultrapure water and ultrasonicating for 30 min, then adding 3 mg Au chloroauric acid into the aqueous solution and stirring for 30 min to allow the two to fully contact;

[0071] S4, 25 μL 0.4 g mL -1 Sodium borohydride aqueous solution was slowly added to the solution described in S3 and stirred vigorously for 60 minutes, then placed on an oil bath and stirred at 70°C for 4 hours. After cooling to room temperature, it was washed with pure water and anhydrous ethanol, and freeze-dried to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

[0072] The gold content in the visible light photocatalyst prepared according to the method of Example 5 is 3 mg.

[0073] Performance Testing

[0074] 1. Structural testing of visible light photocatalysts

[0075] Figure 1 This is a transmission electron microscope image of the visible light photocatalyst in Example 2; it can be clearly seen from the image that the gold nanoparticles are uniformly loaded on the surface of the covalent organic polymer, and the particle size is about 2 nm;

[0076] Figure 2 is a Fourier transform infrared spectrum of the covalent organic polymer and the visible light photocatalyst in Example 2; Figure 2 It can be clearly seen that the covalent organic polymer and the gold-loaded covalent organic polymer visible light photocatalyst in Example 2 have consistent absorption characteristic peaks, which indicates that the introduction of gold nanoparticles does not change the parent polymer structure of the covalent organic polymer.

[0077] 2. Test of visible light photocatalyst synthesis of hydrogen peroxide

[0078] Figure 3 This is a diagram showing the effect of in-situ synthesis of hydrogen peroxide by covalent organic polymer and visible light photocatalyst in Example 2; 10 mg of photocatalyst was dissolved in 50 mL of deionized water, and the solution was stirred in the dark for 30 min after being shielded from light and ultrasonicated for 30 min. It was placed under a 300W xenon lamp with a UV filter for irradiation, and the entire reaction temperature was controlled at about 25°C; 3 mL of the reaction solution was taken in a fixed time period to detect the concentration of hydrogen peroxide, and the method used was iodine titration; 1 ml of potassium hydrogen phthalate solution (0.1 mol·L -1) and potassium iodide solution (0.4 mol·L -1 ) was mixed with the reaction solution and stored in the dark for 30 min; hydrogen peroxide molecules would react with iodine ions (I - ) reacts to generate iodine triion (I3 -) , iodine triion will have a strong absorption peak at 350nm, and this process is detected by UV-vis photometer; the content of hydrogen peroxide can be estimated by the absorption peak intensity at 350nm; it can be clearly seen from the experimental results that compared with the parent material, the performance of visible light photocatalyst for in situ synthesis of hydrogen peroxide has been greatly improved.

[0079] 3. Visible light photocatalyst sterilization test

[0080] Figure 4 The figure is a diagram of the sterilization effect of the covalent organic polymer and the visible light photocatalyst in Example 2; the bacteria used for sterilization are Escherichia coli. Before the experiment, Escherichia coli was first cultured in 75 mL of LB culture medium at a constant temperature of 37°C for 16 h, 1 mL of the bacterial liquid was taken out and centrifuged for 1 min, and washed twice with 0.9% sterile saline, and then the bacteria were cultured in saline; the concentration of the bacterial liquid was 2×10 7 cfu·mL -1 First, 10 mg of photocatalyst was placed in a beaker and mixed with bacteria for dark adsorption for 30 min, and then Fe was added when the light was turned on. 2+ Used to activate the generated hydrogen peroxide to produce hydroxyl radicals, Fe 2+ The concentration was controlled at about 2.7 mM; at specific time intervals, 1 mL of the reaction solution was diluted step by step, and the inactivation of bacteria was observed by the plate counting method; from the experimental results, it can be seen that the sterilization effect of the visible light photocatalyst was significantly enhanced compared with the parent.

[0081] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide, characterized in that: The wet impregnation method is used to impregnate the covalent organic polymer with chloroauric acid, so that the chloroauric acid is evenly distributed on the inner surface of the covalent organic polymer, thereby assisting sodium borohydride reduction to obtain gold nanoparticles and loading them on the covalent organic polymer, which specifically includes the following steps: S1. Under normal temperature conditions, 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) tribenzaldehyde and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl) triphenylamine are dissolved in a ternary solvent consisting of mesitylene, 1,4-dioxane, and 3M acetic acid, the mixed solution is sonicated in an ultrasonic machine and nitrogen is introduced, and then the mixed solution is placed in an oven for reaction to form a light yellow precipitate by self-nucleation, and the reaction is naturally cooled to room temperature after completion; S2, washing the precipitate in the reaction kettle with acetone and tetrahydrofuran respectively, and drying the precipitate in a vacuum oven to obtain a covalent organic polymer; S3, placing the covalent organic polymer obtained in S2 in ultrapure water, ultrasonicating it, and then adding chloroauric acid and stirring to mix well; S4. Slowly add the sodium borohydride aqueous solution to the solution of S3 and stir vigorously for 60 minutes. Then place it on an oil bath and continue stirring until the reaction is complete. After the reaction is completed, naturally cool to room temperature, wash with pure water and anhydrous ethanol, and freeze-dry to obtain a gold-loaded covalent organic polymer visible light photocatalyst.

2. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The volume ratios of mesitylene, 1,4-dioxane and 3M acetic acid in the ternary solvent in S1 are 5:5:1 respectively, and the amount of the ternary solvent added is 11 mL.

3. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The mixed solution in S1 is ultrasonicated for 10-20 min, and nitrogen is introduced for 10-20 min.

4. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The reaction temperature in the oven in S1 is 110-130° C., and the reaction time is 2-4 days.

5. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The drying temperature in S2 is 110-130° C., and the drying time is 8-12 hours.

6. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The volume of the sodium borohydride aqueous solution in S4 is 15-25 μL, and the concentration is 0.2-0.4 g mL -1 .

7. The method for preparing a visible light photocatalyst for in-situ synthesis of hydrogen peroxide according to claim 1, characterized in that: The S4 is stirred in an oil bath at a temperature of 50-70° C. for 2-4 h.

8. A visible light photocatalyst for in-situ synthesis of hydrogen peroxide prepared according to the method of any one of claims 1 to 7.

9. Use of a visible light photocatalyst for in-situ synthesis of hydrogen peroxide prepared by the method according to any one of claims 1 to 7, characterized in that: Gold-loaded covalent organic polymers are used as photocatalysts, visible light is used to reduce oxygen to synthesize hydrogen peroxide in situ, and advanced oxidation technology is combined to sterilize water.

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