CuBi2O4 / Cu-Bi-MOF photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a CuBi2O4 / Cu-Bi-MOF photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of photocatalyst preparation. The preparation method comprises the following steps: dissolving copper salt and bismuth salt to obtain a solution I; dissolving trimesic acid to obtain a solution II; dropwise adding the solution II into the solution I to obtain a solution III; the solution III is subjected to a hydrothermal reaction, and a Cu-Bi-MOF solid is obtained; the Cu-Bi-MOF solid is calcined, so that part of the Cu-Bi-MOF is decomposed and converted into CuBi2O4, and the CuBi2O4 / Cu-Bi-MOF photocatalyst with good interface contact is obtained. The S-type CuBi2O4 / Cu-Bi-MOF heterojunction material with a compact interface is successfully constructed and is used for photocatalytic production of H2O2, and the yield is high. The raw materials are convenient to obtain, the preparation method is simple and easy to operate, and the product is green and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of photocatalyst preparation technology, specifically relating to a CuBi2O4 / Cu-Bi-MOF photocatalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide (H2O2) has wide applications in the food industry, water treatment, healthcare, fuel cells, and as a hydrogen carrier. Currently, H2O2 is mainly produced industrially via the anthraquinone oxidation process. However, this process requires anthraquinone compounds, organic solvents, hydrogen, and oxygen, involves multiple oxidation steps, is highly complex, and consumes a lot of energy. Furthermore, the large amount of waste generated requires treatment before discharge, making the process complex. Therefore, developing novel photocatalysts with broad-spectrum absorption and efficient charge separation performance is a key challenge that urgently needs to be addressed. Currently, photocatalysts for hydrogen peroxide production include TiO2, g-C3N4, and a small number of bismuth-based photocatalysts. However, these photocatalysts have low H2O2 yields and cannot achieve efficient catalytic production of hydrogen peroxide. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a CuBi2O4 / Cu-Bi-MOF photocatalyst, its preparation method, and its applications. This invention successfully constructs an S-type CuBi2O4 / Cu-Bi-MOF heterojunction with a tight interface for photocatalytic production of H2O2, achieving high yield and long-term, high-efficiency photocatalytic production of H2O2. The raw materials used in this invention are low-cost and readily available, the preparation method is simple and efficient, and it avoids the generation of harmful substances, making it environmentally friendly.

[0004] This invention provides the following technical solution: In a first aspect, a method for preparing a CuBi2O4 / Cu-Bi-MOF photocatalyst is provided, comprising the following steps: Copper and bismuth salts were dissolved in ethanol to obtain solution I; Trimethylbenzene was dissolved in N,N-dimethylformamide to obtain solution II; While stirring, add solution II dropwise to solution I and continue stirring to obtain solution III; Solution III was subjected to a hydrothermal reaction. After the reaction was completed, the solution was washed and dried to obtain Cu-Bi-MOF solid. Cu-Bi-MOF solid was calcined to convert part of Cu-Bi-MOF into CuBi2O4, resulting in a heterojunction CuBi2O4 / Cu-Bi-MOF photocatalyst with good interfacial contact.

[0005] Furthermore, the copper salt is copper nitrate trihydrate, the bismuth salt is bismuth nitrate pentahydrate, and the mass ratio of copper nitrate trihydrate, bismuth nitrate pentahydrate, and trimesic acid is (0.5~1.5):(2~6):(2.6~7.8).

[0006] Furthermore, the molar ratio of copper in copper nitrate trihydrate to bismuth in bismuth nitrate pentahydrate is 1:2.

[0007] Furthermore, the concentration of the pyromellitic acid is 0.1~0.5 mol / L.

[0008] Furthermore, the volume ratio of N,N-dimethylformamide to anhydrous ethanol is (1~3):(2~4).

[0009] Furthermore, while stirring, solution II is added dropwise to solution I, and stirring is continued for 1-3 hours to obtain solution III.

[0010] Further, solution III was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and subjected to a hydrothermal reaction at 100-150°C for 8-12 h. After the reaction was completed, the solution was cleaned with deionized water and ethanol alternately and dried at 50-70°C to obtain a light blue Cu-Bi-MOF solid.

[0011] Furthermore, the Cu-Bi-MOF solid was placed in a muffle furnace for calcination. During calcination, the temperature was raised to 300~500℃ and held for 5~30 min, so that some Cu-Bi-MOF was decomposed into CuBi2O4. After the holding time was completed, a CuBi2O4 / Cu-Bi-MOF heterogeneous photocatalyst with good interfacial contact was obtained.

[0012] In a second aspect, a CuBi2O4 / Cu-Bi-MOF photocatalyst prepared by the method described in any one of the first aspects is provided.

[0013] Thirdly, the application of the CuBi2O4 / Cu-Bi-MOF photocatalyst described in the second aspect in the preparation of H2O2 is provided.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention uses an in-situ thermal conversion method to convert part of Cu-Bi-MOF into CuBi2O4, which retains the Cu-Bi-MOF framework and successfully constructs an S-type CuBi2O4 / Cu-Bi-MOF heterojunction photocatalyst with a tight interface. Due to the difference in Fermi levels, a built-in electric field is generated at the interface between CuBi2O4 and Cu-Bi-MOF, thereby forming a band structure that is conducive to charge separation. Under visible light irradiation, the S-type CuBi2O4 / Cu-Bi-MOF heterojunction effectively promotes the separation of photogenerated carriers through the built-in electric field, enabling the recombination of carriers with low redox capabilities, while retaining highly active photogenerated electrons and holes. At the same time, the retained Cu-Bi-MOF framework has a high specific surface area, which can provide more catalytic active sites for the catalytic reaction and enhance the redox capability of the photocatalyst. The photocatalyst provided by this invention has high activity and can be used for photocatalytic production of H2O2. It can enhance the redox ability of the catalytic system and produce H2O2 with high yield. At the same time, the CuBi2O4 / Cu-Bi-MOF photocatalyst provided by this invention has good stability and can achieve long-term and efficient photocatalytic production of H2O2. (2) The raw materials of the present invention are low in cost and easy to obtain, the preparation method is simple and efficient, and at the same time avoids the generation of harmful substances, making it green and environmentally friendly. Attached Figure Description

[0015] Figure 1 This is a SEM image of Cu-Bi-MOF in Comparative Example 1 of this invention; Figure 2 This is a SEM image of CuBi2O4 / Cu-Bi-MOF from Example 1 of the present invention; Figure 3 These are the XRD patterns of CuBi2O4 / Cu-Bi-MOF prepared in Example 1 of the present invention, Cu-Bi-MOF prepared in Comparative Example 1, and CuBi2O4 prepared in Comparative Example 2. Figure 4 These are the infrared spectra of CuBi2O4 / Cu-Bi-MOF prepared in Example 1 of the present invention, Cu-Bi-MOF prepared in Comparative Example 1, and CuBi2O4 prepared in Comparative Example 2. Figure 5 These are the Raman spectra of CuBi₂O₄ / Cu-Bi-MOF prepared in Example 1 of this invention, Cu-Bi-MOF prepared in Comparative Example 1, and CuBi₂O₄ prepared in Comparative Example 2. Figure 6 This is a graph showing the H2O2 cycling performance of CuBi2O4 / Cu-Bi-MOF preparation in Example 1 of this invention; Figure 7 This is a schematic diagram of the charge transfer mechanism of CuBi2O4 / Cu-Bi-MOF in the embodiments of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0017] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0018] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0019] Example 1

[0020] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 25 mL of anhydrous ethanol, denoted as solution I; 1.261 g of trimesic acid was dissolved in 25 mL of N,N-dimethylformamide (DMF), denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 2 h, denoted as solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 120 °C for 10 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid. The Cu-Bi-MOF solid was placed in a muffle furnace and calcined. The temperature was increased to 400 °C at a rate of 10 °C / min and held for 10 min, so that some Cu-Bi-MOF was decomposed into CuBi2O4, and finally a CuBi2O4 / Cu-Bi-MOF heterojunction material with good interfacial contact was formed.

[0021] Example 2

[0022] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 30 mL of anhydrous ethanol, denoted as solution I; 2.522 g of trimesic acid was dissolved in 30 mL of DMF, denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 1 h to obtain solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 100 °C for 8 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid. The Cu-Bi-MOF was placed in a muffle furnace and heated to 400 °C at a rate of 10 °C / min and held for 15 min, causing some Cu-Bi-MOF to decompose into CuBi₂O₄, ultimately forming a CuBi₂O₄ / Cu-Bi-MOF heterojunction material with good interfacial contact.

[0023] Example 3

[0024] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 20 mL of anhydrous ethanol, denoted as solution I; 1.261 g of trimesic acid was dissolved in 20 mL of DMF, denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 1 h to obtain solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 110 °C for 12 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid. The Cu-Bi-MOF was placed in a muffle furnace and heated to 400 °C at a rate of 10 °C / min and held for 20 min, causing partial decomposition of Cu-Bi-MOF into CuBi₂O₄, ultimately forming a CuBi₂O₄ / Cu-Bi-MOF heterojunction material with good interfacial contact.

[0025] Example 4

[0026] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 20 mL of anhydrous ethanol, denoted as solution I; 0.840 g of trimesic acid was dissolved in 25 mL of DMF, denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 2 h to obtain solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 130 °C for 10 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid. The Cu-Bi-MOF was placed in a muffle furnace and heated to 400 °C at a rate of 10 °C / min and held for 25 min, causing some Cu-Bi-MOF to decompose into CuBi₂O₄, ultimately forming a CuBi₂O₄ / Cu-Bi-MOF heterojunction material with good interfacial contact.

[0027] Comparative Example 1

[0028] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 25 mL of anhydrous ethanol, denoted as solution I; 1.261 g of trimesic acid was dissolved in 25 mL of DMF, denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 2 h to obtain solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 120 °C for 10 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid.

[0029] Comparative Example 2

[0030] 0.2416 g of copper nitrate trihydrate and 0.970 g of bismuth nitrate pentahydrate were dissolved in 25 mL of anhydrous ethanol, denoted as solution I; 1.261 g of trimesic acid was dissolved in 25 mL of DMF, denoted as solution II. Solution II was added dropwise to solution I under stirring. After the addition was complete, stirring was continued for 2 h to obtain solution III. Solution III was then transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene and reacted at 120 °C for 10 h. After the reaction, the resulting precipitate was washed several times alternately with deionized water and ethanol, and dried at 60 °C to obtain a pale blue Cu-Bi-MOF solid. The Cu-Bi-MOF was placed in a muffle furnace and heated to 400 °C at a rate of 10 °C / min and held for 2 h to decompose all Cu-Bi-MOF into CuBi₂O₄, obtaining CuBi₂O₄ solid.

[0031] like Figure 1The image shown is a SEM image of Cu-Bi-MOF in Comparative Example 1. Before calcination, Cu-Bi-MOF is a rod-shaped structure with a diameter of 0.2~1.5 µm; Figure 2 The CuBi2O4 / Cu-Bi-MOF of Example 1 is shown. After heat treatment at 400 °C for 10 min, Cu-Bi-MOF is transformed into CuBi2O4 / Cu-Bi-MOF. CuBi2O4 / Cu-Bi-MOF still maintains its rod-shaped morphology and does not undergo significant changes.

[0032] Depend on Figure 3 As shown in the XRD patterns, the Cu-Bi-MOF prepared in Comparative Example 1 exhibits a highly crystalline MOF structure, indicating the successful synthesis of the bimetallic Cu-Bi-MOF. All diffraction peaks of CuBi₂O₄ in Comparative Example 2 are consistent with those of monoclinic CuBi₂O₄ (JCPDS No. 72-0493), and no impurity peaks are observed, indicating that the Cu-Bi-MOF was completely converted to CuBi₂O₄ after heat treatment at 400 °C for 2 h. In contrast, the Cu-Bi-MOF from Example 1, after treatment at 400 °C for 10 min, exhibits broad and weak diffraction peaks, indicating its amorphous structure.

[0033] Depend on Figure 4 The infrared spectrum shown indicates that Cu-Bi-MOF exhibits high activity at 725 cm⁻¹. -1 The absorption peak at 1557 cm⁻¹ is attributed to the out-of-plane bending vibration of the benzene ring CH. -1 and 1365 cm -1 The peaks at 1093 cm⁻¹ correspond to the asymmetric and symmetric stretching vibrations of the carboxylate group, respectively; -1 The vibration peak at 539 cm⁻¹ is attributed to the stretching vibration of COM (M = Cu or Bi); -1 and 451 cm -1 The absorption peaks at 1557 cm⁻¹ correspond to the vibrations of Cu-O and Bi-O in CuBi₂O₄, respectively. In Example 1, the product showed an absorption peak at 1557 cm⁻¹. -1 and 1365 cm -1 Characteristic peaks of carboxylate ions are still present at 539 cm⁻¹, and the intensities of these peaks are significantly weaker than those in Cu-Bi-MOF. -1 and 451 cm -1 Inorganic metal-oxygen bonds of Cu-O and Bi-O appeared at the site, indicating that heat treatment decomposed some organic matter into inorganic phase. With the heat treatment time of Cu-Bi-MOF at 400℃ extended to 2 hours, the 1557 cm⁻¹... -1 and 1365 cm -1 The organic characteristic peaks at 539 cm⁻¹ disappeared. -1 and 451 cm-1 The stronger peak of the inorganic metal-oxygen bond indicates that Cu-Bi-MOF is completely transformed into CuBi2O4.

[0034] Depend on Figure 5 As shown in the Raman spectrum, the Cu-Bi-MOF in Comparative Example 1 that was not calcined exhibits a high Raman spectrum at 812 cm⁻¹. -1 and 743 cm -1 The band at 489 cm⁻¹ is attributed to the C₂C and CH stretching vibrations of the benzene ring; -1 and 440 cm -1 The peaks at these locations correspond to Cu-O and Bi-O bond vibrations. In Comparative Example 2, after heat treatment at 400 ℃ for 2 h, the Cu-Bi-MOF sample showed peaks at 128, 262, and 404 cm⁻¹. -1 Typical CuBi₂O₄ characteristic peaks appeared at the [location], representing CuO₄ plane translational vibration, CuO₄ antiphase rotation, and Bi-O bond stretching vibration, respectively, consistent with the XRD results, indicating that Cu-Bi-MOF was completely transformed into CuBi₂O₄. In Example 1, the Raman signal of the product of Cu-Bi-MOF calcined for 10 min was weak, but characteristic peaks of Cu-Bi-MOF and CuBi₂O₄ could still be identified simultaneously, indicating that Example 1 was a composite of Cu-Bi-MOF and CuBi₂O₄. This further confirms that the preparation method of the present invention can successfully prepare CuBi₂O₄ / Cu-Bi-MOF photocatalysts.

[0035] Application examples

[0036] The CuBi₂O₄ / Cu-Bi-MOF prepared in Examples 1-4 above, the Cu-Bi-MOF prepared in Comparative Examples 1 and 2, and CuBi₂O₄ were used as photocatalysts to prepare H₂O₂. The preparation of H₂O₂ included the following steps: The photocatalyst was added to deionized water containing ethanol and then stirred with O2. A 300 W xenon lamp equipped with a 420 nm cutoff filter was used as the light source to irradiate the deionized water for 0, 30 min, 60 min, 90 min and 120 min. After each irradiation, the suspension was centrifuged and filtered, and the concentration of H2O2 in the treated solution was tested. The test results are shown in Table 1.

[0037] Table 1. Concentration of H2O2 prepared by different photocatalysts at different irradiation times

[0038] As shown in Table 1, different concentrations of H2O2 were generated in Examples 1-4, Comparative Example 1, and Comparative Example 2 as time increased. Under the same irradiation time gradient, the H2O2 concentration prepared by the photocatalysts in Examples 1-4 was significantly higher than that prepared by Comparative Example 1 and Comparative Example 2. This indicates that the H2O2 production activity of CuBi2O4 / Cu-Bi-MOF provided by the present invention is significantly higher than that of single Cu-Bi-MOF and CuBi2O4. This further confirms that the CuBi2O4 / Cu-Bi-MOF prepared by the present invention can be used as a photocatalyst for photocatalytic production of H2O2, and the H2O2 yield is high. Furthermore, the concentration of hydrogen peroxide prepared in Example 1 within 120 min was 1.95 mmol / L, which is superior to the performance of the CuBi2O4@CuBi2S4 photocatalyst published in patent CN111468138A (0.202 mmol / L of hydrogen peroxide prepared within 180 min) and the existing photocatalyst Au / BiVO4@HSnO (0.211 mmol / L of hydrogen peroxide prepared within 120 min), demonstrating a significantly superior photocatalytic hydrogen peroxide production capability.

[0039] As shown in Table 2, the photocatalytic hydrogen peroxide performance of CuBi2O4 / Cu-Bi-MOF in Example 1 of the present invention is 975 μmol / gh, which is superior to the existing photocatalysts fluorine-modified TiO2 (F-(001) face) and bulk g-C3N4.

[0040] Table 2 Performance Comparison

[0041] The performance data of fluorine-modified TiO2 (F-(001) face), bulk g-C3N4 and Au / BiVO4 are from [1], [2] and [3], respectively: [1] Manipulating the H2O2 Reactivity on Pristine Anatase TiO2 withVarious Surface Features and Implications in Oxidation Reactions [J]. TheJournal of Physical Chemistry Letters 2024, 15 (46), 11620-11628. [2] Hydrogen peroxide production under visible light from ultrathin g-C3N4 nanosheets with carbon vacancies [J]. Chemical Industry and Engineering Progress, 2024, 43(7): 4148-4154. [3] Hydroxyl-enriched hydrous tin dioxide-coated BiVO4 with boosted photocatalytic H2O2 production, Chinese Journal of Structural Chemistry, 2024,43(12), 100457, 0254-5861.

[0042] like Figure 6 The figure shown is a performance graph of H2O2 production in Example 1 after 5 cycles. Figure 6 It can be seen that the yield of the CuBi2O4 / Cu-Bi-MOF photocatalyst provided in Example 1 decreased by only 0.2% after 5 cycles of testing, indicating that the photocatalyst provided in Example 1 has good stability. This further confirms that the CuBi2O4 / Cu-Bi-MOF photocatalyst prepared by the preparation method of the present invention has good H2O2 production stability.

[0043] Figure 7 This is a mechanism diagram of CuBi2O4 / Cu-Bi-MOF in an embodiment of the present invention. (See diagram for example.) Figure 7 As shown in (a), when constructing the p-CuBi2O4 / n-Cu-Bi-MOF heterojunction system, due to the difference in Fermi levels when semiconductor catalysts are combined, surface electrons flow from the side with the higher Fermi level to the side with the lower Fermi level. That is, surface electrons of CuBi2O4 flow to Cu-Bi-MOF, causing the Fermi level of p-CuBi2O4 to shift downward and the Fermi level of n-Cu-Bi-MOF to shift upward, eventually reaching an equilibrium state. This results in a built-in electric field (IEF) at the interface, pointing from p-CuBi2O4 to n-Cu-Bi-MOF. This IEF further induces the valence band (VB) of p-CuBi2O4 to bend upward and the conduction band (CB) of n-Cu-Bi-MOF to bend downward, forming a band structure that is conducive to charge separation. Figure 7As shown in (b), under visible light irradiation, the S-type CuBi2O4 / Cu-Bi-MOF heterojunction effectively promotes the separation of photogenerated carriers through its built-in electric field, enabling the recombination of carriers with low redox capabilities while retaining highly active photogenerated electrons and holes. Simultaneously, the photocatalyst prepared in this invention also retains the Cu-Bi-MOF framework. Metal-organic frameworks (MOFs) are considered ideal platforms for achieving efficient photocatalytic H2O2 synthesis due to their high specific surface area and excellent gas adsorption performance. Photocatalysts retaining the Cu-Bi-MOF framework have a large specific surface area, providing more catalytic active sites for the catalytic reaction and enhancing the redox capability of the photocatalyst. The photocatalyst prepared in this invention exhibits a large number of highly active photogenerated carriers under visible light irradiation, resulting in high photocatalyst activity. When used for photocatalytic H2O2 production, it enhances the redox capability of the catalytic system, leading to a high H2O2 yield. Furthermore, the CuBi2O4 / Cu-Bi-MOF photocatalyst provided in this invention has good stability, enabling long-term, efficient photocatalytic H2O2 production.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a CuBi2O4 / Cu-Bi-MOF photocatalyst, characterized in that, It comprises the following steps: dissolving copper salt and bismuth salt in ethanol to obtain solution I; dissolving trimesic acid in N,N-dimethylformamide to obtain solution II; adding solution II into solution I drop by drop under stirring, and continuing to stir to obtain solution III; carrying out hydrothermal reaction on solution III, washing and drying after the reaction to obtain Cu-Bi-MOF solid; calcining Cu-Bi-MOF solid to make part of Cu-Bi-MOF decompose and convert into CuBi2O4, thereby obtaining heterojunction CuBi2O4 / Cu-Bi-MOF photocatalyst with good interface contact. 2.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, The copper salt is copper nitrate trihydrate, and the bismuth salt is bismuth nitrate pentahydrate; the mass ratio of copper nitrate trihydrate, bismuth nitrate pentahydrate and trimesic acid is (0.5-1.5):(2-6):(2.6-7.8). 3.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 2, characterized in that, The molar ratio of copper in the copper nitrate trihydrate to bismuth in the bismuth nitrate pentahydrate is 1:

2. 4.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, The concentration of the trimesic acid is 0.1-0.5 mol / L. 5.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, The volume ratio of solution I to solution II is (1-3):(2-4). 6.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, Adding solution II into solution I drop by drop under stirring, and continuing to stir for 1-3 h to obtain solution III. 7.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, Transferring solution III into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, carrying out hydrothermal reaction at 100-150℃ for 8-12 h, washing with deionized water and ethanol alternately after the reaction, and drying at 50-70℃ to obtain light blue Cu-Bi-MOF solid. 8.The method for preparing CuBi2O4 / Cu-Bi-MOF photocatalyst according to claim 1, characterized in that, Placing Cu-Bi-MOF solid in a muffle furnace for calcination, heating to 300-500℃ for 5-30 min to make part of Cu-Bi-MOF decompose and convert into CuBi2O4, and obtaining CuBi2O4 / Cu-Bi-MOF heterojunction photocatalyst with good interface contact after the heat preservation. 9.A CuBi2O4 / Cu-Bi-MOF photocatalyst prepared by the method of any one of claims 1-8. 10.Use of the CuBi2O4 / Cu-Bi-MOF photocatalyst of claim 9 in preparing H2O2.

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