Ce-MOF enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production and application of Ce-MOF enhanced C3N4 catalyst in fabric rinsing and dye degradation

Abstract

The invention discloses a Ce-MOF enhanced C3N4 catalyst for photocatalytic production of hydrogen peroxide. The Ce-MOF enhanced C3N4 catalyst is prepared from Ce-MOF, sulfide, a carbon-nitrogen precursor and an alkali metal source through high-temperature calcination, the Ce-MOF is prepared by the following steps: adding terephthalic acid into N, N-dimethylformamide for ultrasonic dispersion, then adding a cerium source and formic acid, fully stirring and reacting at 80-100 DEG C, and finally washing, centrifuging and drying. The dosage ratio of the terephthalic acid to the N, N-dimethylformamide to the cerium source to the formic acid is 1g: (10-50) mL: (1-5) g: (5-20) mL; the cerium source is selected from one of ceric ammonium nitrate, cerium chloride and cerium sulfate. The obtained Ce-MOF enhanced C3N4 catalyst has the advantages of high activity, high stability, low cost, simplicity in operation and the like, can overcome the defect of low activity of existing polymer carbon nitride, shows excellent photocatalytic reaction performance, can catalyze optical rinsing of fabrics and degradation of dyes, and is particularly used for catalyzing rinsing of denim and degradation of indigo wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts for photocatalytic production of hydrogen peroxide, specifically to a Ce-MOF enhanced C3N4 catalyst and its preparation, as well as application of the catalyst in fabric bleaching, especially denim bleaching, and degradation of indigo dye. Background Art

[0002] The textile industry has always played a vital role in the process of social, economic and cultural development. It is not only a key industry that promotes economic growth and creates a large number of jobs, but also an important carrier for inheriting and promoting various cultural characteristics. However, with the continuous expansion of the textile industry, the accompanying problem of dye wastewater treatment has become increasingly prominent. It faces many serious problems such as large wastewater discharge volume and complex composition, prominent high chroma problems, strong biological toxicity, and poor biodegradability, which poses a huge challenge to environmental protection. Among them, due to the extremely common application of indigo dye in the field of denim production, indigo wastewater has become a major source of pollution in the field of textile dyeing wastewater, posing a huge risk to human health and the ecological environment that cannot be ignored. Therefore, the degradation treatment of indigo is particularly important and urgent.

[0003] Over the past few decades, with growing awareness of environmental protection and continuous technological advancements, dye treatment technology has made significant progress. Photocatalytic technology stands out due to its unique and significant advantages, including mild reaction conditions, wide applicability, and ability to prevent secondary pollution. Furthermore, heterogeneous advanced oxidation technologies, such as hydrogen peroxide (H2O2), can generate large amounts of reactive oxygen species (ROS) through the Fenton reaction, which can remove various organic pollutants, including dyes. Therefore, using photocatalytic technology to generate hydrogen peroxide can be used for both rinsing denim and degrading indigo dye.

[0004] However, the key to photocatalytic technology lies in the photocatalyst. An efficient photocatalyst must have the following characteristics: a wide light absorption range, excellent light absorption capacity, a band gap structure corresponding to light energy excitation, and photogenerated electrons / holes (e - / h + ) high separation ability and rapid transport. Graphitic carbon nitride (g-C3N4) has recently attracted much attention due to its non-toxicity, good chemical stability, and suitable band gap (≈2.7 eV). However, issues such as small specific surface area, rapid recombination of photogenerated electrons and holes, and weak redox ability hinder its photocatalytic activity. Therefore, the development of C3N4 catalysts with both high activity and high stability will be of great significance for promoting photocatalytic hydrogen peroxide production technology for denim bleaching and indigo dye degradation. Summary of the Invention

[0005] The present invention addresses the technical bottleneck of existing C3N4 catalysts, which have a low photocatalytic hydrogen peroxide production due to their poor activity, and affects the progress of the photocatalytic reaction. The invention provides a Ce-MOF-enhanced C3N4 catalyst, which not only significantly improves the activity and stability of the C3N4 catalyst and excels in hydrogen peroxide production efficiency, but also is convenient to prepare, low in cost, and simple to operate. It is beneficial to promote the rinsing of fabrics and the degradation of dyes, and can especially optimize the rinsing process of denim and the degradation process of indigo dye, thereby significantly promoting the application of C3N4 in the printing and dyeing industry.

[0006] To achieve the above objectives, the present invention provides a Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production, which is prepared by high-temperature calcination of Ce-MOF, sulfide, carbon and nitrogen precursors, and an alkali metal source; The Ce-MOF is prepared by adding terephthalic acid to N,N-dimethylformamide for ultrasonic dispersion, then adding a cerium source and formic acid, stirring and reacting at 80-100°C, and finally washing, centrifuging, and drying. The dosage ratio of the terephthalic acid, N,N-dimethylformamide, cerium source and formic acid is 1g: (10-50)mL: (1-5)g: (5-20)mL; the cerium source is selected from one of ammonium cerium nitrate, cerium chloride and cerium sulfate.

[0007] The catalyst of the present invention modifies the structure of the C3N4 catalyst by simply mixing the raw materials and then calcining them together at high temperature. This allows alkali metal ions and sulfur from the sulfide to enter the Ce-MOF carbide heterojunction structure, while simultaneously creating cyano and nitrogen defects within the heterojunction. This significantly increases the specific surface area of the original catalyst, reduces the photogenerated electron / hole recombination rate, enhances the redox capacity, and thus promotes the catalytic efficiency of C3N4 in the photocatalytic reaction to produce hydrogen peroxide. The Ce-MOF carbide in the raw material uses a MOF in which the rare earth element Ce is in situ loaded to increase defects and narrow the band gap, thereby effectively modifying the C3N4 catalyst structure and improving catalytic activity.

[0008] As a limitation of the above technical solution, Ce-MOF, sulfide, carbon and nitrogen precursor and alkali metal source are mixed in a mass ratio of 1:(1~5):(1~5):(1~5), and then calcined at high temperature.

[0009] As a limitation of the above technical solution, the sulfide is selected from one of thiourea, sulfur, sodium sulfide, cystine, and cysteine; the carbon-nitrogen precursor is selected from one of urea, melamine, and dicyandiamide; and the alkali metal source is selected from one of potassium chloride, lithium chloride, sodium chloride, potassium iodide, sodium iodide, lithium iodide, sodium bromide, potassium bromide, and lithium bromide.

[0010] As a limitation of the above technical solution, the high temperature calcination condition is to keep the temperature at 450-650° C. for 1-6 hours in an air atmosphere.

[0011] As a limitation of the above technical solution, the structure of the Ce-MOF enhanced C3N4 catalyst is a double-defect heterojunction containing cyano groups and N vacancies.

[0012] The obtained Ce-MOF enhanced C3N4 catalyst has a double-defect heterojunction structure.

[0013] Further limit the preparation conditions of the catalyst, such as the reaction treatment conditions and raw material dosage, to effectively regulate the microstructure of the catalyst and improve the catalyst activity and stability.

[0014] The present invention also provides a method for preparing the Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production, comprising the following steps: a. Preparation of Ce-MOF: Add N,N-dimethylformamide and terephthalic acid to a glass flask, ultrasonicate for 10-30 min, then add cerium source and formic acid solution, stir and react in a water bath at 80-100°C for 15-30 min, centrifuge after completion of the reaction, wash, centrifuge, and dry to obtain Ce-MOF; b. Preparation of Ce-MOF enhanced C3N4 catalyst: Ce-MOF, sulfide, carbon nitrogen precursor and alkali metal source were mixed according to the amount, placed in a muffle furnace, and heated to 450-650°C at a rate of 2-5°C / min in an air atmosphere. The temperature was kept at this temperature for 1-6 hours. After the reaction, the material was washed with water several times and centrifuged and dried to obtain the Ce-MOF enhanced C3N4 catalyst.

[0015] As a limitation of the above technical solution, in step a, N,N-dimethylformamide and ethanol are used for washing twice each; and the drying temperature is 60-100°C.

[0016] The preparation of the Ce-MOF enhanced C3N4 catalyst of the present invention is simple to operate, stable product performance can be obtained without complicated treatment, and the promotion and application of the catalyst are convenient.

[0017] At the same time, the present invention also provides the use of the Ce-MOF enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production as described above in fabric rinsing and dye degradation, wherein the Ce-MOF enhanced C3N4 catalyst is used as a catalyst for the photocatalytic hydrogen peroxide production reaction. Preferably, the photocatalytic hydrogen peroxide production reaction using the Ce-MOF enhanced C3N4 catalyst is used for fabric rinsing and / or dye degradation.

[0018] As a limitation of the above technical solution, the photocatalytic hydrogen peroxide production reaction using Ce-MOF enhanced C3N4 catalyst is used in the denim rinsing process and indigo dye degradation process; Preferably, the denim rinsing process is to place the denim in a water washing device containing a Ce-MOF enhanced C3N4 catalyst, the catalyst is immersed in a 10wt% isopropanol solution and wrapped with a semipermeable membrane, the water washing device contains a visible light source for irradiating the catalyst, and oxygen is continuously introduced; The degradation process of indigo dye is to place the wastewater containing indigo dye in a water washing device containing a Ce-MOF enhanced C3N4 catalyst. The catalyst is immersed in a 10wt% isopropanol solution and wrapped by a semipermeable membrane. The water washing device contains a visible light source for irradiating the catalyst.

[0019] As a limitation of the above technical solution, the denim rinsing process is to rinse under visible light for 3 to 6 hours and let it stand in a lightless state for 12 to 24 hours, then take out the denim, wash it with water and dry it, and the K / S reduction value of the obtained denim is not less than 3.5; the degradation process has a 1-hour degradation rate of not less than 60% for a 30 mg / L indigo dye standard solution.

[0020] The Ce-MOF-enhanced C3N4 catalyst of the present invention has the advantages of high hydrogen peroxide yield and stable activity when used in photocatalytic reactions. It is used for rinsing and dye degradation of fabrics, especially denim, and is simple to operate, which has a positive promoting effect on the green development of the textile industry.

[0021] In summary, the Ce-MOF enhanced C3N4 catalyst of the present invention uses MOF carbide and carbon-nitrogen precursors that in situ load the rare earth element Ce, and then adds sulfide and alkali metal sources, and is in situ modified by high-temperature calcination, which significantly improves the microstructure of the catalyst, thereby improving the activity and stability of the C3N4 catalyst, so that it can greatly improve the production efficiency of hydrogen peroxide produced by photocatalytic reaction. Moreover, the application operation is simple, which is beneficial to promote the rinsing of fabrics and the degradation of dyes, especially the rinsing of denim and the degradation process of indigo dye, thereby significantly promoting the application of C3N4 in the printing and dyeing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 , Scanning electron microscope image of the catalyst Ce-MOF / KSCN of Example 1; Figure 2 , XRD pattern of catalyst Ce-MOF / KSCN of Example 1; Figure 3 , hydrogen peroxide production diagram of the catalysts of various examples at different times; Figure 4 , the K / S reduction value of denim fabrics at different times for the catalysts of each embodiment; Figure 5, the dye degradation rate of the catalyst in each embodiment at different times; Figure 6 , infrared images of each catalyst sample of Example 1 and Comparative Example; Figure 7 , UV diffuse reflectance images of each catalyst sample of Example 1 and Comparative Example; Figure 8 , Kulbelka-Munk transformation diagrams of each catalyst sample of Example 1 and Comparative Example; Figure 9 , photocurrent diagrams of the catalysts of Example 1 and Comparative Examples 3 and 4; Figure 10 , hydrogen peroxide standard curve equation. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The experimental methods in the following examples and comparative examples, unless otherwise specified, are conventional methods; the raw materials or test materials used, unless otherwise specified, are typical commercially available products. The quantitative tests in the following examples and comparative examples were all repeated three times, and the results were averaged. Example

[0025] To prepare Ce-MOF enhanced C3N4 catalyst, follow the following steps.

[0026] a. Preparation of Ce-MOF: Add N,N-dimethylformamide to a glass flask, then add terephthalic acid, ultrasonicate for 10-30 min, then add cerium source and formic acid, wherein the amount ratio of terephthalic acid, N,N-dimethylformamide, cerium source, and formic acid is 1g:10-50mL:1-5g:5-20mL, stir and react in a water bath at 80-100°C for 15-30 min, centrifuge after completion of the reaction to obtain a solid, wash the solid twice with N,N-dimethylformamide and ethanol, then centrifuge and dry at 60-100°C to obtain Ce-MOF; b. Preparation of Ce-MOF enhanced C3N4 catalyst: Ce-MOF, sulfide, carbon nitrogen precursor and alkali metal source were mixed according to the amount, placed in a muffle furnace, and heated to 450-650°C at a rate of 2-5°C / min in an air atmosphere. The temperature was kept at this temperature for 1-6 hours. After the reaction, the material was washed with water several times and centrifuged and dried to obtain the Ce-MOF enhanced C3N4 catalyst.

[0027] The catalyst formulation compositions of different embodiments are shown in Table 1.

[0028] Table 1 Catalyst formulations for various examples

[0029] The catalyst sample of Example 1 was taken and recorded as catalyst Ce-MOF / KSCN. The microstructure of the catalyst was detected by scanning electron microscopy and XRD diffraction. Figure 1 SEM images and Figure 2 The XRD pattern of the SEM image shows that the bulk structure is C3N4, and the particles loaded on the surface are Ce-MOF. The XRD pattern shows the peaks of C3N4 and Ce-MOF, proving that the two are successfully composited. Comparative Example 1

[0030] This comparative example is a standard C3N4 catalyst, specifically, 10 g of urea is placed in a muffle furnace, heated to 550° C. at a rate of 2° C. / min under air conditioning, and kept warm for 4 hours, which is recorded as catalyst CN. Comparative Example 2

[0031] This comparative example is a double-defect catalyst, specifically, 10g of urea, 5g of potassium chloride, and 10g of thiourea are mixed evenly, placed in a muffle furnace, and heated to 550°C at a rate of 2°C / min under air atmosphere, and kept warm for 4 hours, which is recorded as catalyst KSCN. Comparative Example 3

[0032] This comparative example is a double-defect heterojunction catalyst, specifically, 5 g of ammonium cerium nitrate, 10 g of urea, 5 g of potassium chloride, and 10 g of thiourea are mixed evenly, placed in a muffle furnace, and heated to 550°C at a rate of 2°C / min under an air atmosphere. The mixture is kept warm for 4 hours and is recorded as catalyst CeO2 / KSCN. Comparative Example 4

[0033] This comparative example is also a double-defect heterojunction catalyst, specifically, 10 g of Ce-MOF (the same as Ce-MOF in Example 1) and 10 g of KSCN (the same as KSCN in Comparative Example 2) are mixed evenly, placed in a muffle furnace, and heated to 550°C at a rate of 2°C / min under air conditioning. The mixture is kept warm for 4 hours and is recorded as catalyst Ce-MOF / KSCN (secondary calcination).

[0034] The catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were used in a photocatalytic hydrogen peroxide production experiment, a photocatalytic denim rinsing experiment, and a photocatalytic indigo aqueous solution degradation experiment, respectively. The performance of each catalyst was demonstrated through the experimental results.

[0035] For the photocatalytic hydrogen peroxide production experiment, 1 g of catalyst was immersed and dispersed in 1 L of a 10 wt% isopropanol solution. The solution was then enclosed in a water-permeable semipermeable membrane and added to the reactor. The reaction solution outside the membrane consisted of water, and oxygen was pre-aerated for 15 minutes to establish a saturated dissolved oxygen environment. A 300 W xenon lamp (AM 1.5G) was used to illuminate the catalyst-containing isopropanol solution vertically from above. A condensation cycle (25 ± 1°C) was also used to ensure efficient mass transfer and thermal equilibrium. From 0 to 60 minutes into the experiment, 2 mL of the reaction solution (i.e., the H₂O₂-containing aqueous solution outside the membrane) was periodically sampled for colorimetric analysis.

[0036] The color developer system uses a KI-ammonium molybdate synergistic catalytic system: accurately weigh 0.498 g KI (0.1 M) and dissolve it in 30 mL of deionized water, and ultrasonically disperse it (40 kHz, 10 min) to obtain a KI solution. Accurately weigh 0.12 g (NH4)2MoO4 (0.01 M) and dissolve it in 10 mL of deionized water, and ultrasonically disperse it (40 kHz, 10 min) to obtain an ammonium molybdate solution. Both solutions should be stored in the dark and prepared immediately before use.

[0037] Take 1 mL of the hydrogen peroxide solution to be tested (i.e. the solution after the reaction solution is filtered through a membrane), 4 mL of KI solution, and 100 μL of ammonium molybdate solution in a centrifuge tube, mix well, and let it stand for 5 minutes. Measure the absorbance at λmax=322nm, and combine Figure 10 Calculate the concentration of hydrogen peroxide using the standard curve equation.

[0038] In a photocatalytic denim rinsing experiment, 1 g of the catalyst was impregnated and dispersed in 1 L of a 10 wt% isopropanol solution. The solution was then enclosed in a semipermeable membrane and placed in a reaction vessel. The reaction solution outside the membrane was water, pre-oxygenated for 15 minutes to establish a saturated dissolved oxygen environment. A 300 W xenon lamp (AM 1.5G) was used to illuminate the catalyst-containing isopropanol solution vertically from above for 2 hours. After the reaction was complete, 0.21 g of sodium silicate and 600 μL of fatty alcohol polyoxyethylene ether were added to the reaction solution outside the membrane. A 4 cm × 4 cm denim sample was then immersed in the reaction solution, achieving in situ generation of hydrogen peroxide and simultaneous bleaching. After immersion bleaching for 0–3 hours, the light and oxygen supply were removed, and the denim sample was allowed to react in the dark for 21 hours. The sample was then removed, washed in 95°C hot water, then in room temperature water, and dried at 80°C.

[0039] Photocatalytic degradation of indigo: 1 g of the catalyst was immersed and dispersed in 1 L of a 10 wt% isopropanol solution, then wrapped with a semipermeable membrane and added to a reaction device. The reaction liquid outside the semipermeable membrane was water. At the same time, indigo dye was added to the reaction liquid to prepare a 30 mg / L indigo dye standard solution. A 300 W xenon lamp light source (AM 1.5G) was used to vertically irradiate the isopropanol solution containing the catalyst from the top (0-60 min). During the experiment, 2 mL of the reaction liquid was collected at regular intervals for absorbance testing and the degradation rate was calculated.

[0040] The data of hydrogen peroxide production, denim K / S reduction value and dye degradation rate corresponding to different photocatalytic reaction times of each catalyst in Examples 1 to 5 are summarized as follows: Figure 3 、 Figure 4 and Figure 5 .

[0041] The performance data of each catalyst in the examples and comparative examples are summarized and shown in Table 2.

[0042] Table 2. Performance data of catalysts in Examples and Comparative Examples

[0043] Results analysis: By changing the synthesis conditions in Examples 1 to 5, the structure of Ce-MOF-enhanced C3N4 can be adjusted to a certain extent, and good catalytic performance can be maintained. The hydrogen peroxide production is all around 2.80 mmol·g -1 ·h -1 The above results show that the K / S reduction value of rinsed jeans is above 3.5, and the dye degradation rate in 1 hour is above 60%.

[0044] The catalyst samples of Example 1 and the comparative example were subjected to infrared, ultraviolet diffuse reflectance and Kulbelka-Munk transformation analysis, wherein the infrared images are as follows: Figure 6 As shown in the figure, it can be seen that the alkali metal K ion doped Example 1 and Comparative Examples 2 to 4 have a high -1 There is a clear peak of cyano group near the UV diffuse reflectance graph. Figure 7 As shown, the Kulbelka-Munk transformation diagram is as follows Figure 8As shown, the results show that the catalyst of Example 1 has a narrower band gap than the catalysts in the comparative examples. Comparative Example 1 is a standard C3N4 catalyst, and due to the lack of defects, its hydrogen peroxide production is relatively low. Comparative Example 2 is a potassium sulfur-doped C3N4 catalyst, and its hydrogen peroxide production is higher than that of Comparative Example 1. However, compared with Example 1, its production is also significantly lower than that of Example 1 due to the lack of a heterojunction structure with the MOF. Comparative Example 3 directly uses ammonium cerium nitrate to calcine with carbon and nitrogen precursors, sulfides, and alkali metal sources. The resulting catalyst is significantly inferior to the heterojunction-forming catalyst Ce-MOF / KSCN (secondary calcination) in all performance data of Comparative Example 4, demonstrating that the Ce source has a significant impact on the activity of the catalyst. Comparative Example 4 uses a heterojunction formed by Ce-MOF and synthesized KSCN, which affects the microstructure of the catalyst and the catalytic effect is significantly inferior to that of Example 1. It can be seen that the preparation method has a direct impact on the structure and activity of the catalyst. Figure 9 The photocurrent diagrams of the catalysts in Example 1 and Comparative Examples 3 and 4 prove that the change in the preparation method changes the light response ability of the catalyst.

[0045] In summary, the Ce-MOF enhanced C3N4 catalyst of the present invention is obtained by simply mixing the MOF carbide loaded with the rare earth element Ce in situ with a carbon nitrogen precursor, a sulfide, and an alkali metal source and then calcining them together at high temperature. The catalyst has the advantages of high activity, high stability, low cost and simple operation. It can overcome the shortcomings of low activity of existing polymer carbon nitrides and exhibit excellent photocatalytic reaction performance, thereby greatly improving the production efficiency of hydrogen peroxide produced by photocatalytic reaction, which is beneficial to promoting the rinsing of fabrics and the degradation of dyes, and especially can optimize the rinsing of denim and the degradation process of indigo dye, thereby significantly promoting the application of C3N4 in the printing and dyeing industry.

Claims

1. A Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production, characterized by: The Ce-MOF enhanced C3N4 catalyst is prepared by calcining Ce-MOF, sulfide, carbon and nitrogen precursors and alkali metal sources at high temperature; The Ce-MOF is prepared by adding terephthalic acid to N,N-dimethylformamide for ultrasonic dispersion, then adding a cerium source and formic acid, stirring and reacting at 80-100°C, and finally washing, centrifuging, and drying. The dosage ratio of the terephthalic acid, N,N-dimethylformamide, cerium source and formic acid is 1g: (10-50)mL: (1-5)g: (5-20)mL; the cerium source is selected from one of ammonium cerium nitrate, cerium chloride and cerium sulfate.

2. The Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 1, characterized in that: Ce-MOF, sulfide, carbon nitrogen precursor and alkali metal source are mixed in a mass ratio of 1:(1~5):(1~5):(1~5) and then calcined at high temperature.

3. The Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 1, characterized in that: The sulfide is selected from one of thiourea, sulfur, sodium sulfide, cystine, and cysteine; the carbon-nitrogen precursor is selected from one of urea, melamine, and dicyandiamide; and the alkali metal source is selected from one of potassium chloride, lithium chloride, sodium chloride, potassium iodide, sodium iodide, lithium iodide, sodium bromide, potassium bromide, and lithium bromide.

4. The Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 1, characterized in that: The high temperature calcination condition is to keep the temperature at 450~650℃ for 1~6 hours in air atmosphere.

5. The Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 1, characterized in that: The structure of the Ce-MOF enhanced C3N4 catalyst is a double-defect heterojunction containing cyano groups and N vacancies.

6. A method for preparing a Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to any one of claims 1 to 5, characterized in that: The following steps are included: a. Preparation of Ce-MOF: Add N,N-dimethylformamide and terephthalic acid to a glass flask, ultrasonicate for 10-30 min, then add cerium source and formic acid solution, stir and react in a water bath at 80-100°C for 15-30 min, centrifuge after completion of the reaction, wash, centrifuge, and dry to obtain Ce-MOF; b. Preparation of Ce-MOF enhanced C3N4 catalyst: Ce-MOF, sulfide, carbon nitrogen precursor and alkali metal source were mixed according to the amount, placed in a muffle furnace, and heated to 450-650°C at a rate of 2-5°C / min in an air atmosphere. The temperature was kept at this temperature for 1-6 hours. After the reaction, the mixture was washed with water, centrifuged and dried to obtain a Ce-MOF enhanced C3N4 catalyst.

7. The method for preparing a Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 6, characterized in that: In step a, N,N-dimethylformamide and ethanol are used for washing; and the drying temperature is 60-100°C.

8. Use of the Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to any one of claims 1 to 7 in fabric rinsing and dye degradation, characterized in that: The Ce-MOF enhanced C3N4 catalyst is used as a catalyst for the photocatalytic hydrogen peroxide production reaction. Preferably, the photocatalytic hydrogen peroxide production reaction using the Ce-MOF enhanced C3N4 catalyst is used for fabric rinsing and / or dye degradation.

9. The use of a Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 8, characterized in that: The photocatalytic hydrogen peroxide production reaction using Ce-MOF enhanced C3N4 catalyst was used in the denim rinsing process and indigo dye degradation process; Preferably, the denim rinsing process is to place the denim in a water washing device containing a Ce-MOF enhanced C3N4 catalyst, the catalyst is immersed in a 10wt% isopropanol solution and wrapped with a semipermeable membrane, the water washing device contains a visible light source for irradiating the catalyst, and oxygen is continuously introduced; The degradation process of indigo dye is to place the wastewater containing indigo dye in a water washing device containing a Ce-MOF enhanced C3N4 catalyst. The catalyst is immersed in a 10wt% isopropanol solution and wrapped by a semipermeable membrane. The water washing device contains a visible light source for irradiating the catalyst.

10. The use of a Ce-MOF-enhanced C3N4 catalyst for photocatalytic hydrogen peroxide production according to claim 9, characterized in that: The denim rinsing process involves rinsing under visible light for 3 to 6 hours and leaving it in a dark state for 12 to 24 hours. The denim is then taken out, washed, and dried, and the K / S reduction value of the resulting denim is no less than 3.

5. The degradation process requires a 1-hour degradation rate of no less than 60% for a 30 mg / L indigo dye standard solution.

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