Preparation of Bi2O3 / Zr-BTB composite photocatalytic material and application of Bi2O3 / Zr-BTB composite photocatalytic material in photocatalytic degradation of phenol

Abstract

The invention relates to preparation of a Bi2O3 / Zr-BTB composite photocatalytic material and application of the Bi2O3 / Zr-BTB composite photocatalytic material in photocatalytic degradation of phenol. The preparation method comprises the following steps: step 1, weighing ZrCl4 and 1, 3, 5-tri (4-carboxyphenyl) benzene, and adding N, N-dimethylformamide into the ZrCl4 and the 1, 3, 5-tri (4-carboxyphenyl) benzene; obtaining a mixed solution, performing ultrasonic treatment on the mixed solution, and sequentially adding formic acid and distilled water; heating, cooling to room temperature, and drying to obtain a Zr-BTB nanosheet; 2, bismuth nitrate is added into a mixed solution composed of ammonia water and deionized water, then the mixed solution is fully dispersed, and then the solution is put into a hydrothermal kettle; after the solid is precipitated, putting the precipitate into a crucible, carrying out hydrothermal reaction in a muffle furnace, taking out a sample, cooling to room temperature, and collecting Bi2O3; step 3, respectively weighing Bi2O3 and the Zr-BTB nanosheet, respectively putting the Bi2O3 and the Zr-BTB nanosheet into an N, N-dimethylformamide solvent, and carrying out ultrasonic treatment; the Bi2O3 solution is dropwise added into the Zr-BTB nanosheet solution; and after the reaction is finished, taking out a sample, and cooling the sample to room temperature to obtain the Bi2O3 / Zr-BTB composite photocatalytic material. The method has the characteristics of simple synthesis process, greenness and environmental protection.

Description

Technical Field

[0001] This invention belongs to the technical field of visible light-induced MOF composite material degradation of phenol pollutants in water, specifically involving the preparation of a Bi2O3 / Zr-BTB composite photocatalytic material and its application in photocatalytic degradation of phenol. Background Technology

[0002] Among numerous water pollutants, phenol is of particular concern. Phenol is widely used in the production of important chemical products such as phenolic resins and caprolactam, and is a crucial raw material for fine chemicals such as dyes, pharmaceuticals, perfumes, and pesticides. However, phenol is difficult to biodegrade and is highly toxic. Current phenol wastewater treatment technologies mainly include adsorption, biological methods, and advanced oxidation processes. For example, Chen Liqun et al. (China Pulp & Paper, 2020, 39(05):23-28) used black liquor lignin and Fenton sludge as raw materials and potassium hydroxide as an activator to prepare magnetic activated carbon (MAC) to treat phenol wastewater. When the MAC dosage was 500 mg / L and the initial phenol concentration was 200 mg / L, the equilibrium adsorption capacity of MAC for phenol reached 98 mg / g. Liu et al. (Chemosphere, 2022, 294:133732) selected halophilic archaea and their extracellular polymers to treat high-salt phenol-containing wastewater, and the phenol degradation rate reached 83.7%. Abou-Talab et al. (Water and Environment Journal, 2020, 35(1):259-268) used graphite electrodes as anodes and stainless steel electrodes as cathodes. When the initial phenol concentration was about 6.8 mg / L and the current density was 3 mA / cm², the MAC achieved a high-salt phenol degradation rate of 98 mg / g. 2 The treatment time was 15 minutes, and the phenol removal rate reached 100%. Manasfi et al. (Comprehensive Analytical Chemistry, 2021, 92:85-116) found that when ozone was used for removal, the removal rate reached 99% within 30 minutes when the initial phenol concentration was 100 mg / L.

[0003] However, the above-mentioned water treatment technologies are not very effective in treating emerging pollutants such as phenols. Photocatalytic degradation technology, as an emerging technology for removing organic pollutants, has become a research hotspot for scholars at home and abroad. Metal-organic frameworks (MOFs) are ideal composite materials for constructing photocatalytic degradation of organic pollutants due to their inherent and uniformly distributed catalytic active sites, high specific surface area and porosity. For example, the team of Ouyang Gangfeng (Angew. Chem. Int. Ed., 2024, 63(45): e202412279) used CC covalently to connect MIL-68 and COF-V to prepare a series of MIL-68@COF-Vs materials with highly controllable shell thickness and interpenetration, which were used for the efficient degradation of various pollutants: under solar irradiation, 96.5% of tetracycline was successfully degraded within 15 min, 97.6% of rhodamine 6G was degraded within 25 min, and 95.3% of phenol was degraded within 40 min. Wang et al. (Surfaces and Interfaces, 2024, 48, 104319) demonstrated that Ag3PO4 combined with Ni-MOF via in-situ precipitation can effectively degrade phenol. Under visible light irradiation, the Ag-Ni-70 / CQDs-0.45 composite material achieved a degradation rate of 98% for 10 mg / L phenol within 30 minutes, with a corresponding rate constant of 0.0620 min. -1 Wang Zhijuan (Modern Chemical Industry, 2025, https: / / link.cnki.net / urlid / 11.2172.TQ.20250521.1051.021.) prepared a CdS-modified MIL-88B(Fe)S-type heterojunction composite material. When the concentration of 2-chlorophenol was 15 mg / L (50 mL) and the composite material loading was 12 mg, the degradation rate of 2-chlorophenol reached 88.4% after 2 hours of light irradiation.

[0004] However, these MOF composites have limited ability to degrade phenolic pollutants. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a preparation method for Bi2O3 / Zr-BTB composite photocatalytic material and its application in photocatalytic degradation of phenol. The preparation method is simple, green and environmentally friendly.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A Bi2O3 / Zr-BTB composite photocatalytic material is composed of Bi2O3 particles supported on Zr-BTB nanosheets.

[0008] Bi2O3 was loaded onto Zr-BTB nanosheets via a solvothermal method to form a Z-shaped heterojunction. The conduction band potential of the Z-shaped heterojunction was lower than that of the Zr-BTB nanosheets, while its valence band potential was higher than that of Bi2O3. This enhanced its redox ability while suppressing electron-hole pair recombination.

[0009] The thickness of the Zr-BTB nanosheets is approximately 2.5 nm;

[0010] A method for preparing a Bi2O3 / Zr-BTB composite photocatalytic material includes the following steps;

[0011] Step 1: Preparation of Zr-BTB nanosheets

[0012] ZrCl4 and 1,3,5-tris(4-carboxyphenyl)benzene (C) were weighed sequentially into a transparent glass bottle. 27 H 18 Add N,N-dimethylformamide (DMF) to O6; obtain a mixed solution; sonicate the mixed solution and then add formic acid and distilled water in sequence; seal with tin foil and place in an oven for heating, then cool to room temperature; wash three times with DMF and ethanol respectively; dry to obtain Zr-BTB nanosheet samples;

[0013] Step 2: Preparation of Bi2O3

[0014] First, bismuth nitrate (Bi(NO3)3·5H2O) was added to a mixed solution of ammonia (NH3·H2O) and deionized water. The mixed solution was then fully dispersed and placed in a hydrothermal reactor. The material was washed with ethanol and deionized water. After the solid precipitate was formed, the precipitate was placed in a crucible and hydrothermally reacted in a muffle furnace. The sample was then removed and allowed to cool naturally to room temperature before the precipitate was collected, which is Bi2O3.

[0015] Step 3: Preparation of Bi2O3 / Zr-BTB composite material

[0016] Bi₂O₃ and Zr-BTB nanosheets were weighed separately and placed in N,N-dimethylformamide (DMF) solvent. The Bi₂O₃ and Zr-BTB nanosheet solutions were ultrasonically treated. Then, the Bi₂O₃ solution was slowly added dropwise to the Zr-BTB nanosheet solution to promote thorough and uniform mixing of the two components. The mixture was then transferred to a hydrothermal reactor. After the hydrothermal reaction was completed, the sample was removed and allowed to cool naturally to room temperature. It was then washed three times with deionized water and anhydrous ethanol alternately to remove impurities and allowed to air dry naturally at room temperature to obtain the Bi₂O₃ / Zr-BTB composite photocatalytic material.

[0017] In step 1, the molar ratio of ZrCl4, 1,3,5-tris(4-carboxyphenyl)benzene and DMF is 1.5:1:1 to 2:1:1.

[0018] In step 1, the molar ratio of ZrCl4, 1,3,5-tris(4-carboxyphenyl)benzene and formic acid is 1.5:1:3.8-2:1:5.

[0019] In step 1, the oven is heated at 120°C for 24-48 hours.

[0020] In step 2, the ratio of bismuth nitrate to ammonia is in the range of 8.5:1 to 9:1.

[0021] In step 2, the mixed solution is placed on a magnetic stirrer and stirred continuously at 500-600 rpm for 1-1.5 hours to fully disperse it. The mixture is then placed in a hydrothermal reactor and heated in an oven at 200°C for 12 hours.

[0022] In step 2, the temperature inside the muffle furnace is increased to 550°C at a heating rate of 5-10°C / min, and the hydrothermal reaction is carried out for 3 hours.

[0023] In step 2, the precipitated product is washed three times alternately with deionized water and anhydrous ethanol to remove impurities, and finally a yellow powder material, namely Bi2O3, is obtained, which is sealed and stored in a sample tube for later use.

[0024] In step 3, the mass ratio between Bi2O3 and Zr-BTB nanosheets is 2:3-10:17.

[0025] In step 3, the mixture is continuously stirred at 500-600 rpm for 1 hour on a magnetic stirrer; and then reacted at 120°C in an oven for 12-24 hours to ensure that the two components are fully and evenly mixed.

[0026] The Bi2O3 / Zr-BTB composite photocatalytic material is used for the photocatalytic degradation of phenol.

[0027] Degradation conditions: visible light, 20 mg Bi2O3 / Zr-BTB composite material, 20 mg / L phenol.

[0028] The beneficial effects of this invention are:

[0029] The composite of Zr-BTB nanosheets and Bi2O3 forms a Z-shaped heterojunction. This composite material retains the lower conduction band potential of Zr-BTB nanosheets and the higher valence band potential of Bi2O3, which enhances its redox ability while suppressing electron-hole pair recombination and improving the photocatalytic performance of the material.

[0030] The Bi₂O₃ / Zr-BTB composite photocatalyst (20 mg) achieved a degradation efficiency of up to 97% for 20 mg / L phenol within 35 min, with a degradation rate constant of 0.1133 min. -1 .

[0031] Under extreme conditions (pH=1), the Bi2O3 / Zr-BTB composite photocatalyst achieved a degradation efficiency of 87% for phenol within 35 min, with a degradation rate constant of 0.0422 min. -1 .

[0032] In anion (I - CO3 2- ) and cations (Ca 2+ Co 2+ Even in the presence of ), the Bi2O3 / Zr-BTB composite photocatalyst can still efficiently degrade phenol pollutants;

[0033] In step 1 of the method, Zr-BTB nanosheets can be obtained by adjusting the amount of formic acid and DMF. The ultrathin nanosheet structure effectively reduces the carrier transport distance, accelerates carrier migration, and exposes Zr activation centers.

[0034] In step 3 of the method, by adjusting the ratio of Zr-BTB nanosheets and Bi2O3, a Z-shaped heterojunction of Bi2O3 / Zr-BTB composite material can be obtained, which promotes the effective separation and transport of photogenerated carriers and significantly improves the photocatalytic activity. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of Zr-BTB nanosheets. Structural analysis shows that Zr-BTB nanosheets are a two-dimensional layered structure.

[0036] Figure 2 This is an atomic force microscopy image of Zr-BTB nanosheets.

[0037] Figure 3 These are X-ray powder diffraction patterns of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB.

[0038] Figure 4 These are the infrared spectra of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB.

[0039] Figure 5The following are X-ray photoelectron spectra of Bi2O3, Zr-BTB nanosheets and Bi2O3 / Zr-BTB: XPS total spectrum of Bi2O3 (a) and Bi 4f spectrum (b); XPS total spectrum of Zr-BTB nanosheets (c) and Zr 3d spectrum (d); XPS total spectrum of Bi2O3 / Zr-BTB (e), Zr 3d spectrum (f) and Bi 4f spectrum (g).

[0040] Figure 6 The microstructure and elemental distribution mappings of Bi2O3, Zr-BTB nanosheets and Bi2O3 / Zr-BTB are shown: (ae)Bi2O3; (fj)Zr-BTB nanosheets; (ko)Bi2O3 / Zr-BTB.

[0041] Figure 7 Here are high-resolution morphology images of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB: (a) Bi2O3; (b) Zr-BTB nanosheets; (c) Bi2O3 / Zr-BTB.

[0042] Figure 8 These are the UV-Vis diffuse reflectance spectra and band gap energies of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB.

[0043] Figure 9 The Mott-Schottky diagrams and charge carrier densities of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB at different frequencies are shown.

[0044] Figure 10 These are transient photocurrent spectra of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB.

[0045] Figure 11 These are impedance spectra of Bi2O3, Zr-BTB nanosheets, and Bi2O3 / Zr-BTB.

[0046] Figure 12 The UV absorption curves of phenol degradation and elimination by different loading amounts of Bi2O3 / Zr-BTB over time are shown: (a) Bi2O3 / Zr-BTB loading amount is 5 mg; (b) Bi2O3 / Zr-BTB loading amount is 15 mg; (c) Bi2O3 / Zr-BTB loading amount is 20 mg; (d) Bi2O3 / Zr-BTB loading amount is 25 mg.

[0047] Figure 13The first-order kinetic curves of phenol degradation and elimination by Bi2O3 / Zr-BTB with different loading amounts are shown: (a) Bi2O3 / Zr-BTB loading amount of 5 mg; (b) Bi2O3 / Zr-BTB loading amount of 15 mg; (c) Bi2O3 / Zr-BTB loading amount of 20 mg; (d) Bi2O3 / Zr-BTB loading amount of 25 mg.

[0048] Figure 14 The UV absorption curves of 10 mg Bi2O3 / Zr-BTB on the degradation and elimination of phenol at different concentrations over time are as follows: (a) phenol concentration of 5 mg / L; (b) phenol concentration of 10 mg / L; (c) phenol concentration of 15 mg / L; (d) phenol concentration of 20 mg / L; (e) phenol concentration of 30 mg / L; (f) phenol concentration of 50 mg / L.

[0049] Figure 15 The first-order kinetic curves of the degradation and elimination of phenol by 10 mg Bi2O3 / Zr-BTB at different concentrations are shown: (a) phenol concentration of 5 mg / L; (b) phenol concentration of 10 mg / L; (c) phenol concentration of 15 mg / L; (d) phenol concentration of 20 mg / L; (e) phenol concentration of 30 mg / L; (f) phenol concentration of 50 mg / L.

[0050] Figure 16 The UV absorption curves of phenol degradation and elimination by Bi2O3 / Zr-BTB in solutions with different pH values ​​are as follows: (a) pH=1; (b) pH=3; (c) pH=5; (d) pH=8; (e) pH=10; (f) pH=12.

[0051] Figure 17 The first-order kinetic curves of phenol degradation and elimination by Bi2O3 / Zr-BTB in solutions with different pH values ​​are shown: (a) pH=1; (b) pH=3; (c) pH=5; (d) pH=8; (e) pH=10; (f) pH=12.

[0052] Figure 18 The degradation and removal efficiency of phenol by Bi2O3 / Zr-BTB composite material in the presence of different interfering ions is as follows: (a) degradation and removal efficiency of phenol by Bi2O3 / Zr-BTB composite material in the presence of different interfering anions; (b) degradation and removal efficiency of phenol by Bi2O3 / Zr-BTB composite material in the presence of different interfering cations.

[0053] Figure 19 This is a diagram illustrating the mechanism by which Bi2O3 / Zr-BTB composite materials degrade phenol pollutants. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to the accompanying drawings.

[0055] Example 1:

[0056] Preparation of Zr-BTB nanosheets

[0057] 10.12 mg of ZrCl4 and 12.5 mg of 1,3,5-tris(4-carboxyphenyl)benzene (C) were weighed into a transparent glass bottle in sequence. 27 H 18 Add 1.5 mL of N,N-dimethylformamide (DMF) to a glass bottle. Sonicate the mixture for 20 min, then add 0.75 mL of formic acid and 0.15 mL of distilled water. Seal the bottle with aluminum foil and heat at 120 °C for 48 h. Finally, cool to room temperature and wash three times with DMF and ethanol by centrifugation.

[0058] Preparation of Bi2O3

[0059] First, 1.2 g of bismuth nitrate (Bi(NO3)3·5H2O) was added to a mixed solution consisting of 10 mL of ammonia water (NH3·H2O) and 8 mL of deionized water. The mixture was then stirred continuously at 600 rpm for 1 hour on a magnetic stirrer to ensure thorough dispersion. The mixture was then transferred to a hydrothermal reactor and reacted at 200°C for 12 hours. The material was washed with ethanol and deionized water, and after precipitation, the precipitate was placed in a crucible and heated to 550°C in a muffle furnace at a rate of 5°C / min for 3 hours. Afterward, the sample was removed and allowed to cool naturally to room temperature. The precipitate was collected and washed three times alternately with deionized water and anhydrous ethanol to remove impurities, finally yielding a yellow powder material, which was sealed and stored in a sample tube for later use.

[0060] Preparation of Bi2O3 / Zr-BTB composite material

[0061] 0.1 g of Bi₂O₃ and 0.17 g of Zr-BTB nanosheets were weighed separately. The Bi₂O₃ and Zr-BTB nanosheets were each placed in 10 mL of N,N-dimethylformamide (DMF) solvent and ultrasonically treated for 15 min. Then, the Bi₂O₃ solution was slowly added dropwise to the Zr-BTB nanosheet solution, and the mixture was stirred continuously at 600 rpm for 1 h on a magnetic stirrer to ensure thorough and uniform mixing of the two components. The mixture was transferred to a hydrothermal reactor, sealed, and placed in an oven at 120 °C for 12 h. After the reaction was complete, the sample was removed and allowed to cool naturally to room temperature. It was then washed three times alternately with deionized water and anhydrous ethanol to remove impurities and allowed to air dry at room temperature to obtain the Bi₂O₃ / Zr-BTB composite material.

[0062] In this embodiment, Bi2O3 was successfully loaded onto Zr-BTB nanosheets in the Bi2O3 / Zr-BTB composite material. X-ray powder diffraction (PXRD) analysis showed that the diffraction peaks of Bi2O3 / Zr-BTB matched well with those of Bi2O3 and Zr-BTB nanosheets, proving the successful preparation of the Bi2O3 / Zr-BTB composite material. Infrared (IR) spectroscopy showed that the peaks at 3233.3, 1623.8, 1541.2, 1245.4, and 629.8 cm⁻¹ were... -1 The stretching vibrations corresponding to CH, C=O, C=C, Zr-O, and Bi-O bonds respectively indicate the successful synthesis of the Bi2O3 / Zr-BTB composite material. Compared with Bi2O3 and Zr-BTB nanosheets, the Bi2O3 / Zr-BTB composite material exhibits a significantly increased light absorption range, a significantly improved transient photocurrent response, and a smaller impedance, indicating that the composite of Bi2O3 and Zr-BTB can effectively avoid the recombination of photogenerated electrons and holes in the catalyst, thus effectively improving the charge separation efficiency.

[0063] Example 2:

[0064] Preparation of Zr-BTB nanosheets

[0065] 10.12 mg of ZrCl4 and 12.5 mg of 1,3,5-tris(4-carboxyphenyl)benzene (C) were weighed into a transparent glass bottle in sequence. 27 H 18 Add 1.5 mL of N,N-dimethylformamide (DMF) to a glass bottle. Sonicate the mixture for 20 min, then add 0.75 mL of formic acid and 0.25 mL of distilled water sequentially. Seal the bottle with aluminum foil and heat at 120 °C for 48 h. Finally, cool to room temperature and wash three times with DMF and ethanol to obtain the Zr-BTB sample.

[0066] Preparation of Bi2O3

[0067] First, 1.2 g of bismuth nitrate (Bi(NO3)3·5H2O) was added to a mixed solution consisting of 10 mL of ammonia water (NH3·H2O) and 8 mL of deionized water. The mixture was then stirred continuously at 600 rpm for 1 hour on a magnetic stirrer to ensure thorough dispersion. The solution was then transferred to a hydrothermal reactor and placed in an oven at 200°C for 12 hours. The material was then washed with ethanol and deionized water. After precipitation, the precipitate was placed in a crucible and heated to 550°C in a muffle furnace at a rate of 5°C / min for 3 hours. The sample was then removed and allowed to cool naturally to room temperature. The precipitate was collected and washed three times alternately with deionized water and anhydrous ethanol to remove impurities, ultimately yielding a yellow powder material, which was sealed and stored in a sample tube for later use.

[0068] Preparation of Bi2O3 / Zr-BTB composite material

[0069] 0.1 g of Bi₂O₃ and 0.1 g of Zr-BTB nanosheets were weighed separately. The Bi₂O₃ and Zr-BTB nanosheets were each placed in 10 mL of N,N-dimethylformamide (DMF) solvent and ultrasonically treated for 15 min. Then, the Bi₂O₃ solution was slowly added dropwise to the Zr-BTB nanosheet solution, and the mixture was stirred continuously at 600 rpm for 1 h on a magnetic stirrer to ensure thorough and uniform mixing of the two components. The mixture was transferred to a hydrothermal reactor, sealed, and placed in an oven at 120 °C for 12 h. After the reaction was complete, the sample was removed and allowed to cool naturally to room temperature. It was then washed three times alternately with deionized water and anhydrous ethanol to remove impurities and allowed to air dry at room temperature to obtain the Bi₂O₃ / Zr-BTB composite material.

[0070] In this embodiment, Bi2O3 was successfully loaded onto Zr-BTB nanosheets in the Bi2O3 / Zr-BTB composite material. X-ray powder diffraction (PXRD) analysis showed that the diffraction peaks of Bi2O3 / Zr-BTB matched well with those of Bi2O3 and Zr-BTB nanosheets, proving the successful preparation of the Bi2O3 / Zr-BTB composite material. Infrared (IR) spectroscopy showed that the peaks at 3233.3, 1623.8, 1541.2, 1245.4, and 629.8 cm⁻¹ were... -1 The stretching vibrations corresponding to CH, C=O, C=C, Zr-O, and Bi-O bonds respectively indicate the successful synthesis of the Bi2O3 / Zr-BTB composite material. Compared with Bi2O3 and Zr-BTB nanosheets, the Bi2O3 / Zr-BTB composite material exhibits a significantly increased light absorption range, a significantly improved transient photocurrent response, and a smaller impedance, indicating that the composite of Bi2O3 and Zr-BTB can effectively avoid the recombination of photogenerated electrons and holes in the catalyst, thus effectively improving the charge separation efficiency.

[0071] Example 3:

[0072] Preparation of Zr-BTB nanosheets

[0073] 10 mg of ZrCl4 and 10 mg of 1,3,5-tris(4-carboxyphenyl)benzene (C) were weighed into a transparent glass bottle in sequence. 27 H 18Add 3 mL of N,N-dimethylformamide (DMF) to a glass bottle. Sonicate the mixture for 20 min, then add 0.91 mL of formic acid. Seal the bottle with aluminum foil and heat at 120°C for 24 h. Finally, cool to room temperature and wash three times with DMF and ethanol by centrifugation.

[0074] Preparation of Bi2O3

[0075] First, 1.2 g of bismuth nitrate (Bi(NO3)3·5H2O) was added to a mixed solution consisting of 10 mL of ammonia water (NH3·H2O) and 8 mL of deionized water. The mixture was then stirred continuously at 600 rpm for 1 hour on a magnetic stirrer to ensure thorough dispersion. The solution was then transferred to a hydrothermal reactor and placed in an oven at 200°C for 12 hours. The material was then washed with ethanol and deionized water. After precipitation, the precipitate was placed in a crucible and heated to 550°C in a muffle furnace at a rate of 5°C / min for 3 hours. The sample was then removed and allowed to cool naturally to room temperature. The precipitate was collected and washed three times alternately with deionized water and anhydrous ethanol to remove impurities, ultimately yielding a yellow powder material, which was sealed and stored in a sample tube for later use.

[0076] Preparation of Bi2O3 / Zr-BTB composite material

[0077] 0.1 g of Bi₂O₃ and 0.24 g of Zr-BTB nanosheets were weighed separately. The Bi₂O₃ and Zr-BTB nanosheets were each placed in 10 mL of N,N-dimethylformamide (DMF) solvent and ultrasonically treated for 15 min. Then, the Bi₂O₃ solution was slowly added dropwise to the Zr-BTB nanosheet solution, and the mixture was stirred continuously at 600 rpm for 1 h on a magnetic stirrer to ensure thorough and uniform mixing. The mixture was then transferred to a hydrothermal reactor, sealed, and placed in an oven at 120 °C for 12 h. After the reaction was complete, the sample was removed and allowed to cool naturally to room temperature. It was then washed three times alternately with deionized water and anhydrous ethanol to remove impurities and allowed to air dry at room temperature to obtain the Bi₂O₃ / Zr-BTB composite material.

[0078] In this embodiment, Bi2O3 was successfully loaded onto Zr-BTB nanosheets in the Bi2O3 / Zr-BTB composite material. X-ray powder diffraction (PXRD) analysis showed that the diffraction peaks of Bi2O3 / Zr-BTB matched well with those of Bi2O3 and Zr-BTB nanosheets, proving the successful preparation of the Bi2O3 / Zr-BTB composite material. Infrared (IR) spectroscopy showed that the peaks at 3233.3, 1623.8, 1541.2, 1245.4, and 629.8 cm⁻¹ were... -1The stretching vibrations corresponding to CH, C=O, C=C, Zr-O, and Bi-O bonds respectively indicate the successful synthesis of the Bi2O3 / Zr-BTB composite material. Compared with Bi2O3 and Zr-BTB nanosheets, the Bi2O3 / Zr-BTB composite material exhibits a significantly increased light absorption range, a significantly improved transient photocurrent response, and a smaller impedance, indicating that the composite of Bi2O3 and Zr-BTB can effectively avoid the recombination of photogenerated electrons and holes in the catalyst, thus effectively improving the charge separation efficiency.

[0079] Example 4:

[0080] Preparation of Zr-BTB nanosheets

[0081] 10.12 mg of ZrCl4 and 12.5 mg of 1,3,5-tris(4-carboxyphenyl)benzene (C) were weighed into a transparent glass bottle in sequence. 27 H 18 Add 5 mL of N,N-dimethylformamide (DMF) to a glass bottle. Sonicate the mixture for 5 min, then add 0.91 mL of formic acid and 0.25 mL of distilled water. Seal the bottle with aluminum foil and heat at 120°C for 48 h. Finally, cool to room temperature and wash three times with DMF and ethanol by centrifugation.

[0082] Preparation of Bi2O3

[0083] First, 1.2 g of bismuth nitrate (Bi(NO3)3·5H2O) was added to a mixed solution consisting of 10 mL of ammonia water (NH3·H2O) and 8 mL of deionized water. The solution was then stirred continuously at 600 rpm for 1 hour on a magnetic stirrer to ensure thorough dispersion. The solution was then transferred to a hydrothermal reactor and placed in an oven at 200°C for 12 hours. After washing the material with ethanol and deionized water, the precipitate was placed in a crucible and heated to 550°C in a muffle furnace at a rate of 5°C / min for 3 hours. The sample was then removed and allowed to cool naturally to room temperature. The precipitate was collected and washed three times alternately with deionized water and anhydrous ethanol to remove impurities, ultimately yielding a yellow powder material, which was sealed and stored in a sample tube for later use.

[0084] Preparation of Bi2O3 / Zr-BTB composite material

[0085] 0.1 g of Bi₂O₃ and 0.31 g of Zr-BTB nanosheets were weighed separately. The Bi₂O₃ and Zr-BTB nanosheets were each placed in 10 mL of N,N-dimethylformamide (DMF) solvent and ultrasonically treated for 15 min. Then, the Bi₂O₃ solution was slowly added dropwise to the Zr-BTB nanosheet solution, and the mixture was stirred continuously at 600 rpm for 1 h on a magnetic stirrer to ensure thorough and uniform mixing. The mixture was then transferred to a hydrothermal reactor, sealed, and placed in an oven at 120 °C for 12 h. After the reaction was complete, the sample was removed and allowed to cool naturally to room temperature. It was then washed three times alternately with deionized water and anhydrous ethanol to remove impurities and allowed to air dry at room temperature to obtain the Bi₂O₃ / Zr-BTB composite material.

[0086] In this embodiment, Bi2O3 was successfully loaded onto Zr-BTB nanosheets in the Bi2O3 / Zr-BTB composite material. X-ray powder diffraction (PXRD) analysis showed that the diffraction peaks of Bi2O3 / Zr-BTB matched well with those of Bi2O3 and Zr-BTB nanosheets, proving the successful preparation of the Bi2O3 / Zr-BTB composite material. Infrared (IR) spectroscopy showed that the peaks at 3233.3, 1623.8, 1541.2, 1245.4, and 629.8 cm⁻¹ were... -1 The stretching vibrations corresponding to CH, C=O, C=C, Zr-O, and Bi-O bonds respectively indicate the successful synthesis of the Bi2O3 / Zr-BTB composite material. Compared with Bi2O3 and Zr-BTB nanosheets, the Bi2O3 / Zr-BTB composite material exhibits a significantly increased light absorption range, a significantly improved transient photocurrent response, and a smaller impedance, indicating that the composite of Bi2O3 and Zr-BTB can effectively avoid the recombination of photogenerated electrons and holes in the catalyst, thus effectively improving the charge separation efficiency.

[0087] Morphological characterization of Bi2O3, Zr-BTB nanosheets and Bi2O3 / Zr-BTB composites: Zr-BTB nanosheets are ultrathin two-dimensional structures. Figure 1 Atomic force microscopy (AFM) showed that the thickness of the Zr-BTB nanosheets was approximately 2.5 nm. Figure 2 X-ray powder diffraction (PXRD) analysis showed that the diffraction peaks of Bi2O3 / Zr-BTB matched well with those of Bi2O3 and Zr-BTB nanosheets, proving the successful preparation of the Bi2O3 / Zr-BTB composite material. Figure 3 The infrared (IR) spectra of Bi₂O₃ / Zr-BTB show that at 3233.3, 1623.8, 1541.2, 1245.4, and 629.8 cm⁻¹, [the desired effect is not specified in the original text]. -1The stretching vibrations corresponding to CH, C=O, C=C, Zr-O, and Bi-O bonds respectively indicate the successful synthesis of the Bi2O3 / Zr-BTB composite material. Figure 4 X-ray photoelectron spectroscopy (XPS) showed that Bi₂O₃ / Zr-BTB contained Zr 3d, Bi 4f, C 1s, and O 1s peaks. Figure 5 e). The peak values ​​at 180.4 eV and 183.0 eV are respectively Zr 3+ 3D 5 / 2 and Zr 4+ 3D 3 / 2 Compared to Zr-BTB, Zr 3+ 3D 5 / 2 and Zr 4+ 3D 3 / 2 The value decreases ( Figure 5 f); The peak values ​​at 158.2 eV and 163.4 eV are respectively Bi 4f in Bi2O3 / Zr-BTB. 7 / 2 and Bi 4f 5 / 2 Compared to Bi2O3, Bi4f 7 / 2 and Bi4f 5 / 2 The value decreases ( Figure 5 g). The decrease in Zr 3d and Bi 4f values ​​in Bi2O3 / Zr-BTB indicates a possible interaction between Bi2O3 and Zr-BTB. Scanning electron microscopy (SEM) images of Bi2O3 / Zr-BTB demonstrate the successful composite of Bi2O3 and Zr-BTB nanosheets. Figure 6 Transmission electron microscopy (TEM) of Bi2O3 / Zr-BTB revealed the presence of Zr(011), ZrBi2(101), and Bi2O3(111) crystal planes, indicating the successful preparation of the Bi2O3 / Zr-BTB composite material. Figure 7 ).

[0088] Photoelectric Properties Study of Bi₂O₃, Zr-BTB Nanosheets and Bi₂O₃ / Zr-BTB Composites: UV-Vis spectroscopy studies show that the absorption wavelengths of Bi₂O₃ / Zr-BTB are 262-291 nm and 364-406 nm, respectively. Compared with Zr-BTB (259-303 nm), the significantly increased absorption wavelength range indicates that Bi₂O₃ / Zr-BTB has potentially excellent photocatalytic performance. Figure 8 a) The band gaps of Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB were calculated based on the Tauc plot, which describes the relationship between the frequency and optical absorption coefficient of semiconductor materials. Figure 8As shown in b, the estimated band gaps for Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB are 2.79, 3.25, and 2.63 eV, respectively. Mott-Schottky (MS) measurements (1500, 2000, 2500 Hz) show that the flat band potentials for Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB are -0.5, -1.74, and -0.52 V (versus Ag / AgCl). Figure 9 The slope of the tangent line reflects the n-type semiconductor characteristics of Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB. Therefore, the lowest unoccupied molecular orbital (LUMO) energy levels of Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB are -0.4, -1.64, and -0.42 V, respectively, which are related to E(O₂ / O₂) ·- Compared to (-0.33V), Bi₂O₃, Zr-BTB, and Bi₂O₃ / Zr-BTB exhibit relatively low potentials, indicating that these materials are more effective in photocatalytically generating superoxide anion radicals (O₂). ·- This demonstrates considerable potential. Based on the above results, the highest occupied molecular orbital (HOMO) energy levels of Bi2O3, Zr-BTB, and Bi2O3 / Zr-BTB were obtained as 2.39, 1.61, and 2.21 V, respectively. Notably, the HOMO energy level of Bi2O3 / Zr-BTB is more positive than the oxidation potential of phenol (0.84-1.0 V), indicating that Bi2O3 / Zr-BTB can serve as a visible light-driven photocatalyst for the degradation and elimination of phenol pollutants.

[0089] To further investigate the separation efficiency of photogenerated electrons and holes in Bi2O3, Zr-BTB, and Bi2O3 / Zr-BTB photocatalysts, transient photocurrent response and electrochemical impedance spectroscopy (EIS) tests were conducted. The transient photocurrent response results showed that the transient photocurrent response of Bi2O3 / Zr-BTB was significantly improved compared to Bi2O3 and Zr-BTB. Specifically, the photocurrent density of Bi2O3 / Zr-BTB was nearly 1.5 times that of Bi2O3 and nearly twice that of Zr-BTB. Figure 10 Electrochemical impedance spectroscopy showed that Bi2O3 / Zr-BTB had the lowest impedance compared to Bi2O3 and Zr-BTB. Figure 11 This indicates that the composite of Bi2O3 and Zr-BTB can effectively avoid the recombination of photogenerated electrons and holes in the catalyst, thus effectively improving the charge separation efficiency. Figure 19As shown, the photocatalytic degradation performance of phenol by Bi2O3 / Zr-BTB composite material was studied: The synthesized Bi2O3 / Zr-BTB composite material was applied to the photocatalytic degradation of phenol. Firstly, the effect of Bi2O3 / Zr-BTB composite material loading on phenol degradation efficiency was studied. The results showed that with increasing Bi2O3 / Zr-BTB loading (5 mg → 25 mg), both the degradation efficiency and degradation rate constant of phenol gradually increased. Figure 12 and Figure 13 When the phenol concentration was 20 mg / L, the photocatalyst loading was 20 mg, and the degradation time was 35 min, the phenol degradation efficiency reached as high as 97%. Figure 12 c) The degradation rate constant is 0.1133 min. -1 ( Figure 13 c). Studies on the effect of phenol concentration on phenol degradation efficiency show that as the phenol concentration increases (5 mg / L → 70 mg / L), the degradation efficiency of phenol gradually decreases. Figure 14 and Figure 15 When the photocatalyst loading was 10 mg, the phenol concentration was 20 mg / L, and the time was 55 min, the phenol degradation efficiency reached 80%. Figure 14 d) The degradation rate constant is 0.034 min. -1 ( Figure 15 d). In summary, 20 mg Bi2O3 / Zr-BTB composite material and 20 mg / L phenol were selected as the optimal reaction conditions for subsequent research on the photocatalytic degradation of phenol by Bi2O3 / Zr-BTB composite material.

[0090] Under optimal conditions, the effect of solution pH on phenol degradation performance studies show that the Bi2O3 / Zr-BTB composite material still exhibits good degradation performance for phenol in acidic, neutral, and weakly alkaline solutions (pH = 1-10). Figure 16 and Figure 17 It is worth mentioning that when the solution pH = 1 and the time is 35 minutes, the degradation efficiency of phenol reaches 87%. Figure 16 a) The degradation rate constant is 0.0422 min. -1 ( Figure 17 a). To test the practicality of the Bi2O3 / Zr-BTB composite material, various interfering anions (I₂O₃ / Zr-BTB) were added to the solution. - PO4 3- CO3 2- SO3 2- ), cations (Cd) 2+ Na + Co 2+ Ni 2+ Zn 2+ Ca 2+The study investigated the effect of interfering ions on the degradation and removal performance of phenol. The results showed that, in I... - CO3 2- Co 2+ and Ca 2+ Even in the presence of interfering ions, Bi2O3 / Zr-BTB still exhibits high degradation efficiency for phenol pollutants. Figure 18 ).

Claims

1. A Bi₂O₃ / Zr-BTB composite photocatalytic material, characterized in that, It consists of Bi2O3 particles supported on Zr-BTB nanosheets.

2. The Bi₂O₃ / Zr-BTB composite photocatalytic material according to claim 1, characterized in that, Bi2O3 was loaded onto Zr-BTB nanosheets via a solvothermal method to form a Z-shaped heterojunction. The Z-shaped heterojunction has a lower conduction band potential than Zr-BTB nanosheets and a higher valence band potential than Bi2O3, which enhances its redox ability while suppressing electron-hole pair recombination.

3. The Bi₂O₃ / Zr-BTB composite photocatalytic material according to claim 1, characterized in that, Zr-BTB nanosheets are ultrathin two-dimensional structures with a thickness of approximately 2.5 nm.

4. A method for preparing a Bi₂O₃ / Zr-BTB composite photocatalytic material according to any one of claims 1-3, characterized in that, Includes the following steps; Step 1: Weigh ZrCl4 and 1,3,5-tris(4-carboxyphenyl)benzene in sequence and add them to N,N-dimethylformamide; obtain a mixed solution, sonicate the mixed solution and then add formic acid and distilled water in sequence; heat, cool to room temperature, and dry to obtain Zr-BTB nanosheet samples; Step 2: First, add bismuth nitrate to a mixed solution of ammonia and deionized water, then disperse the mixed solution thoroughly, and then put the solution into a hydrothermal reactor; after the solid precipitates, place the precipitate in a crucible and perform a hydrothermal reaction in a muffle furnace. Then, take out the sample and let it cool naturally to room temperature before collecting Bi2O3. Step 3: Weigh out Bi2O3 and Zr-BTB nanosheets separately and place them in N,N-dimethylformamide solvent. Sonicate the Bi2O3 and Zr-BTB nanosheet solutions. Then, slowly add the Bi2O3 solution to the Zr-BTB nanosheet solution to promote thorough and uniform mixing of the two components. Transfer the above mixed solution to a hydrothermal reactor. After the hydrothermal reaction is completed, remove the sample and allow it to cool naturally to room temperature. Let it air dry at room temperature to finally obtain the Bi2O3 / Zr-BTB composite photocatalytic material.

5. The preparation method of a Bi2O3 / Zr-BTB composite photocatalytic material according to claim 4, characterized in that, In step 1, the molar ratio of ZrCl4, 1,3,5-tris(4-carboxyphenyl)benzene, and N,N-dimethylformamide is: 1.5:1:1-2:1:1； In step 1, the molar ratio of ZrCl4, 1,3,5-tris(4-carboxyphenyl)benzene, and formic acid is: 1.5:1:3.8-2:1:5。 6. The method for preparing a Bi2O3 / Zr-BTB composite photocatalytic material according to claim 4, characterized in that, In step 1, the oven is heated at 120°C for 24-48 hours.

7. The preparation method of a Bi2O3 / Zr-BTB composite photocatalytic material according to claim 4, characterized in that, In step 2, the ratio of bismuth nitrate to ammonia is in the range of 8.5:1 to 9:

1.

8. The preparation method of the Bi2O3 / Zr-BTB composite photocatalytic material according to claim 4, characterized in that, In step 2, the mixed solution is placed on a magnetic stirrer and stirred continuously at a speed of 500-600 rpm for 1-1.5 hours to fully disperse it. The mixture is then placed in a hydrothermal reactor and heated in an oven at 200°C for 12 hours. In step 2, the temperature inside the muffle furnace is increased to 550°C at a heating rate of 5-10°C / min, and the hydrothermal reaction is carried out for 3 hours. In step 2, the precipitated product is washed three times alternately with deionized water and anhydrous ethanol to remove impurities, and finally a yellow powder material, namely Bi2O3, is obtained, which is sealed and stored in a sample tube for later use.

9. The preparation method of a Bi2O3 / Zr-BTB composite photocatalytic material according to claim 4, characterized in that, In step 3, the mass ratio of Bi2O3 to Zr-BTB nanosheets is 2:3-10:

17. In step 3, the two components are thoroughly and evenly mixed on a magnetic stirrer at a speed of 500-600 rpm for 1 hour; the mixture is then reacted at 120°C in an oven for 12-24 hours.

10. The application of the Bi2O3 / Zr-BTB composite photocatalytic material prepared by the method according to any one of claims 4-9, characterized in that, The Bi2O3 / Zr-BTB composite photocatalytic material is used for the photocatalytic degradation of phenol. Degradation conditions: visible light, 20 mg Bi2O3 / Zr-BTB composite material, 20 mg / L phenol.

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