Iodine-doped biocl photocatalyst and preparation method and application thereof

Abstract

The application discloses an iodine-doped BiOCl photocatalyst and a preparation method and application thereof, and the preparation method comprises the following steps: S1, mixing polyethylene glycol and deionized water to prepare a premix solution, adding a water-soluble bismuth salt into the premix solution, and uniformly stirring to obtain a first mixed solution; S2, adding a water-soluble chlorine salt into the first mixed solution, and uniformly stirring at room temperature to obtain a second mixed solution; S3, adding a water-soluble iodine salt into the second mixed solution, and uniformly stirring at room temperature to obtain a pre-product; and S4, separating, washing and drying the precipitate in the pre-product. The preparation method has the advantages of simple steps, mild conditions, low energy consumption, environmental protection, easy scale production, and the like, the prepared iodine-doped BiOCl photocatalyst has the advantages of wide visible light response range, high photo-generated carrier separation efficiency, excellent photocatalytic activity and good stability, and the like, and the iodine-doped BiOCl photocatalyst has high photocatalytic degradation capacity for ciprofloxacin, tetracycline and rhodamine B, and has a wide application prospect in the field of sewage treatment.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic material preparation technology, specifically, it relates to an iodine-doped BiOCl photocatalyst, its preparation method and application. Background Technology

[0002] Recalcitrant pollutants such as antibiotics and organic dyes are widely present in medical, domestic, agricultural, and industrial wastewater, posing a serious threat to global water safety and human health. Because these pollutants exhibit biological resistance or have stable chemical structures, they are difficult to remove efficiently using traditional physical adsorption, flocculation sedimentation, and biodegradation technologies. To address this issue, photocatalytic degradation technology has been developed in recent years. Photocatalytic degradation is an advanced oxidation technology based on semiconductor photocatalysis. Due to its advantages such as directly utilizing sunlight to drive the reaction, mild reaction conditions, and the potential for deep mineralization of pollutants, it is considered one of the most promising environmental remediation technologies.

[0003] However, the commercial application of this technology has long been constrained by two major bottlenecks: first, common wide-bandgap semiconductors (such as TiO2) can only absorb a small portion of ultraviolet light from sunlight, resulting in low solar energy utilization; second, the rapid recombination rate of photogenerated electrons and holes leads to low quantum efficiency. Therefore, developing novel visible light photocatalysts that combine broad spectral response with efficient carrier separation capabilities has become the key to overcoming these technical bottlenecks.

[0004] In recent years, bismuth-based semiconductors have attracted widespread attention due to their many excellent properties: (1) Bismuth-based semiconductors have visible light response characteristics, enabling them to efficiently utilize solar energy; (2) Bismuth-based semiconductors have a unique layered structure, which is stable and conducive to ion and charge transport; (3) The electronic band structure of bismuth-based semiconductors is tunable, allowing for the directional design of electronic properties; (4) Bismuth-based semiconductors have excellent chemical stability and can maintain long-term stability under harsh conditions. Among bismuth-based semiconductors, bismuth oxyhalides (BiOX, X=Cl, Br, I) series materials have particularly outstanding performance and have shown great application potential. Among them, BiOCl has the advantages of a relatively positive valence band potential and strong oxidation ability, but its band gap is relatively wide (about 3.4 eV), which seriously limits its absorption and utilization of visible light. In contrast, BiOI has a narrower band gap (about 1.8 eV) and excellent visible light capture ability, but its conduction band potential is relatively positive, resulting in a fast recombination rate of photogenerated carriers and a relatively weak oxidation ability. Therefore, the above two types of bismuth oxyhalides are still difficult to meet the application requirements for degrading pollutants in industrial wastewater. In addition, traditional bismuth halide photocatalysts are usually prepared by high-pressure hydrothermal / solvothermal methods or high-temperature calcination methods. These preparation methods have problems such as high energy consumption, harsh reaction conditions, complex process steps or the need to use organic solvents. They have high production costs and environmental and safety hazards, which limit the large-scale production and practical application of photocatalysts.

[0005] In view of this, it is necessary to further improve the existing preparation methods of bismuth halide photocatalysts. Summary of the Invention

[0006] Therefore, the technical problem to be solved by this invention is that the performance of existing bismuth halides is difficult to meet the requirements for degrading pollutants in industrial wastewater, and the preparation methods are energy-intensive and costly, subject to harsh conditions, complex processes, and pose environmental load and safety hazards. Therefore, this invention proposes an iodine-doped BiOCl photocatalyst with excellent performance, easy preparation, simple preparation process, mild conditions, and green environmental protection, as well as its preparation method and application.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: The first aspect of this invention provides a method for preparing an iodine-doped BiOCl photocatalyst, the method comprising the following steps: S1. Polyethylene glycol is mixed with deionized water to prepare a premixed solution. Water-soluble bismuth salt is added to the premixed solution and stirred until homogeneous to obtain a first mixed solution. The mass percentage of the water-soluble bismuth salt in the first mixed solution is 2-30 wt%. S2. Add water-soluble chloride salt to the first mixed solution and stir evenly at room temperature to obtain a second mixed solution, wherein the molar ratio of the water-soluble chloride salt to the water-soluble bismuth salt is 0.6-0.99:1; S3. Add water-soluble iodine salt to the second mixed solution and stir evenly at room temperature to obtain a preproduct. The molar ratio of the water-soluble iodine salt to the water-soluble bismuth salt is 0.01-0.4:1. S4. Separate, wash, and dry the precipitate in the preproduct.

[0008] Preferably, the water-soluble bismuth salt is Bi(NO3)3·5H2O or bismuth acetate.

[0009] Preferably, the water-soluble chloride salt is potassium chloride or sodium chloride.

[0010] Preferably, the water-soluble iodized salt is potassium iodide or sodium iodide.

[0011] Preferably, the molecular weight of the polyethylene glycol is 200-20000.

[0012] Preferably, the premixed liquid contains polyethylene glycol at a mass percentage of 0.2-1 wt%.

[0013] Preferably, in step S1, the stirring time at room temperature is 30-120 min; in step S2, the stirring time at room temperature is 30-120 min; and in step S3, the stirring time at room temperature is 30-120 min.

[0014] Preferably, in step S4, the drying process is vacuum drying, with a temperature of 40-60°C and a drying time of 6-8 hours.

[0015] A second aspect of the present invention provides an iodine-doped BiOCl photocatalyst, wherein the iodine-doped BiOCl photocatalyst is prepared by the above method.

[0016] The third aspect of this invention provides an application of the iodine-doped BiOCl photocatalyst in the photocatalytic degradation of organic pollutants in wastewater, wherein the organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0017] The technical solution of the present invention has the following advantages compared with the prior art: The method for preparing iodine-doped BiOCl photocatalyst provided by the present invention includes the following steps: S1, mixing polyethylene glycol with deionized water to obtain a premixed solution, adding water-soluble bismuth salt to the premixed solution, stirring evenly to obtain a first mixed solution, wherein the mass percentage of water-soluble bismuth salt in the first mixed solution is 2-30 wt%; S2, adding water-soluble chloride salt to the first mixed solution, stirring evenly at room temperature to obtain a second mixed solution, wherein the molar ratio of water-soluble chloride salt to water-soluble bismuth salt is 0.6-0.99:1; S3, adding water-soluble iodine salt to the second mixed solution, stirring evenly at room temperature to obtain a preproduct, wherein the molar ratio of water-soluble iodine salt to water-soluble bismuth salt is 0.01-0.4:1; S4, separating and washing the precipitate in the preproduct, and drying it. This method is a solvent-free, room-temperature hydrolysis precipitation method. The procedure is simple, requires no complex equipment, has mild preparation conditions, low energy consumption, is environmentally friendly, and is easy to scale up. The resulting iodine-doped BiOCl photocatalyst has a wide visible light response range, high photogenerated carrier separation efficiency, excellent photocatalytic activity, and good stability. It exhibits highly efficient photocatalytic degradation capabilities for various recalcitrant organic pollutants such as ciprofloxacin, tetracycline, and rhodamine B, and has broad application prospects in the field of wastewater treatment. Attached Figure Description

[0018] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 These are XRD test images of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 of this application; Figure 2 This is an enlarged schematic diagram of the 26°-36° section in the XRD test image; Figure 3 These are FT-IR test images of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 of this application; Figure 4 (a)-(c) are SEM images of the photocatalyst provided in Example 1 of this application; Figure 4 (d) is an EDS image of the photocatalyst provided in Example 1 of this application; Figure 4 (e) is a distribution map of elements; Figure 4 (f) is a TEM image of the photocatalyst provided in Example 1 of this application; Figure 4 (g) is an HR-TEM test image of the photocatalyst provided in Example 1 of this application; Figure 4 (h) is a SAED image of the photocatalyst provided in Example 1 of this application. Figure 5 The adsorption-desorption curve of the photocatalyst provided for Comparative Example 1; Figure 6 This is an adsorption-desorption curve of the photocatalyst provided in Example 1 of this application; Figure 7 (a) is the full XPS spectrum of the photocatalyst provided in Example 1 of this application; Figure 7 (b) is the high-resolution XPS spectrum of Bi 4f; Figure 7 (c) is the high-resolution XPS spectrum of Cl 2p; Figure 7 (d) is the high-resolution XPS spectrum of I 3d; Figure 7 (e) is the O 1s high-resolution XPS spectrum. Figure 8 The ultraviolet-visible diffuse reflectance spectra of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 of this application; Figure 9 These are the band structure calculation curves of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 of this application; Figure 10 Schottky curve of the photocatalyst provided in Example 1 of this application; Figure 11 (a)-(b) are Schottky curves of the photocatalysts provided in Comparative Examples 1-2; Figure 12 The photocatalytic degradation curves of CIP under visible light provided by the photocatalysts in Examples 1-4 and Comparative Examples 1-2 of this application are shown. Figure 13 The kinetic fitting curve for CIP degradation; Figure 14The UV-Vis absorption spectra of the photocatalyst provided in Example 1 of this application for the degradation of CIP in the dark and under visible light irradiation; Figure 15 This is a cyclic experimental test diagram of the photocatalyst degradation of CIP provided in Example 1 of this application; Figure 16 The test results show the degradation of CIP by the photocatalysts provided in Example 1 and Comparative Example 1 of this application under visible light irradiation. Figure 17 The test results show the degradation of CIP, TC and RhB by the photocatalyst provided in Example 1 of this application under visible light and simulated sunlight irradiation. Figure 18 The adsorption and photocatalytic degradation curves of CIP by the photocatalyst provided in Example 1 of this application under free radical capture; Figure 19 Histogram of photocatalytic degradation of CIP by the photocatalyst provided in Example 1 of this application under free radical capture; Figure 20 The fluorescence spectrum of the photocatalyst provided in Example 1 of this application under visible light irradiation is obtained by the terephthalic acid fluorescent probe method for detecting hydroxyl radicals. Figure 21 This is a diagram illustrating the photocatalytic degradation mechanism of the photocatalyst provided in Example 1 of this application. Figure 22 Transient photocurrent test diagrams of the photocatalysts provided in Example 1 and Comparative Example 1 of this application; Figure 23 Electrochemical impedance spectroscopy (EIS) plots of the photocatalysts provided in Example 1 and Comparative Example 1 of this application; Figure 24 The fluorescence spectra of the photocatalysts provided in Example 1 and Comparative Example 1 of this application are shown. Detailed Implementation

[0019] Example 1 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, wherein the general formula of the iodine-doped BiOCl photocatalyst is BiOCl. 1-x I x , where x is 0.01-0.4.

[0020] In this embodiment, the preparation method specifically includes the following steps: S1. Polyethylene glycol (PEG-2000) with a molecular weight of 2000 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 1 wt%. Bi(NO3)3·5H2O is added to the premixed solution and stirred at room temperature for 60 min until the mixture is homogeneous to obtain a first mixed solution. The mass percentage of water-soluble bismuth salt in the first mixed solution is 3 wt%.

[0021] S2. Add potassium chloride (KCl) to the first mixed solution and stir at room temperature for 60 minutes until homogeneous to obtain the second mixed solution, wherein the molar ratio of KCl to Bi(NO3)3·5H2O is 0.9:1.

[0022] S3. Add potassium iodide (KI) to the second mixed solution and stir at room temperature for 60 min until homogeneous to obtain the preproduct. The molar ratio of KI to Bi(NO3)3·5H2O is 0.1:1.

[0023] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 60℃ for 6 hours to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.9 I 0.1 .

[0024] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0025] Example 2 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, which specifically includes the following steps: S1. Polyethylene glycol (PEG-200) with a molecular weight of 200 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 0.2 wt%. Bi(NO3)3·5H2O is added to the premixed solution and stirred at room temperature for 30 min until the mixture is homogeneous to obtain a first mixed solution. The mass percentage of water-soluble bismuth salt in the first mixed solution is 5 wt%.

[0026] S2. Add potassium chloride (KCl) to the first mixed solution and stir at room temperature for 90 minutes until homogeneous to obtain the second mixed solution, wherein the molar ratio of KCl to Bi(NO3)3·5H2O is 0.8:1.

[0027] S3. Add potassium iodide (KI) to the second mixed solution and stir at room temperature for 30 minutes until homogeneous to obtain the preproduct. The molar ratio of KI to Bi(NO3)3·5H2O is 0.2:1.

[0028] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 40℃ for 8 hours to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.8 I 0.2 .

[0029] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0030] Example 3 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, which specifically includes the following steps: S1. Polyethylene glycol (PEG-20000) with a molecular weight of 20000 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 1 wt%. Bi(NO3)3·5H2O is added to the premixed solution and stirred at room temperature for 120 min until homogeneous to obtain a first mixed solution. The mass percentage of water-soluble bismuth salt in the first mixed solution is 10 wt%.

[0031] S2. Add potassium chloride (KCl) to the first mixed solution and stir at room temperature for 120 min until homogeneous to obtain the second mixed solution, wherein the molar ratio of KCl to Bi(NO3)3·5H2O is 0.7:1.

[0032] S3. Add potassium iodide (KI) to the second mixed solution and stir at room temperature for 60 min until homogeneous to obtain the preproduct. The molar ratio of KI to Bi(NO3)3·5H2O is 0.3:1.

[0033] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 60℃ for 6 hours to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.7 I 0.3 .

[0034] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0035] Example 4 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, which specifically includes the following steps: S1. Polyethylene glycol (PEG-10000) with a molecular weight of 10000 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 0.6 wt%. Bi(NO3)3·5H2O is added to the premixed solution and stirred at room temperature for 90 min until homogeneous to obtain a first mixed solution. The mass percentage of water-soluble bismuth salt in the first mixed solution is 20 wt%.

[0036] S2. Add potassium chloride (KCl) to the first mixed solution and stir at room temperature for 50 minutes until homogeneous to obtain the second mixed solution, wherein the molar ratio of KCl to Bi(NO3)3·5H2O is 0.6:1.

[0037] S3. Add potassium iodide (KI) to the second mixed solution and stir at room temperature for 120 min until homogeneous to obtain the preproduct. The molar ratio of KI to Bi(NO3)3·5H2O is 0.4:1.

[0038] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 50°C for 7 hours to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.6 I 0.4 .

[0039] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0040] Example 5 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, which specifically includes the following steps: S1. Polyethylene glycol (PEG-5000) with a molecular weight of 5000 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 0.5 wt%. Bismuth acetate (Bi(CH3COO)3) is added to the premixed solution and stirred at room temperature for 50 min until homogeneous to obtain a first mixed solution. The mass percentage of Bi(CH3COO)3 in the first mixed solution is 15 wt%.

[0041] S2. Add sodium chloride (NaCl) to the first mixed solution and stir at room temperature for 45 minutes until homogeneous to obtain the second mixed solution, wherein the molar ratio of NaCl to Bi(CH3COO)3 is 0.99:1.

[0042] S3. Add sodium iodide (NaI) to the second mixed solution and stir at room temperature for 55 min until homogeneous to obtain the preproduct. The molar ratio of NaI to Bi(CH3COO)3 is 0.01:1.

[0043] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 55℃ for 8 hours to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.99 I 0.01 .

[0044] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0045] Example 6 This embodiment provides a method for preparing an iodine-doped BiOCl photocatalyst, which specifically includes the following steps: S1. Polyethylene glycol (PEG-2000) with a molecular weight of 2000 is mixed with deionized water to prepare a premixed solution. The mass percentage of polyethylene glycol in the premixed solution is 0.7 wt%. Bismuth acetate (Bi(CH3COO)3) is added to the premixed solution and stirred at room temperature for 100 min until homogeneous to obtain a first mixed solution. The mass percentage of Bi(CH3COO)3 in the first mixed solution is 25 wt%.

[0046] S2. Add sodium chloride (NaCl) to the first mixed solution and stir at room temperature for 70 minutes until homogeneous to obtain the second mixed solution, wherein the molar ratio of NaCl to Bi(CH3COO)3 is 0.6:1.

[0047] S3. Add sodium iodide (NaI) to the second mixed solution and stir at room temperature for 40 min until homogeneous to obtain the preproduct. The molar ratio of NaI to Bi(CH3COO)3 is 0.4:1.

[0048] S4. After separating the precipitate from the preproduct and washing it with deionized water, dry it at 45℃ for 7.5 h to obtain the iodine-doped BiOCl photocatalyst: BiOCl 0.6 I 0.4 .

[0049] The iodine-doped BiOCl photocatalyst prepared by the method provided in this embodiment can be applied to the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are at least one of ciprofloxacin, rhodamine B, and tetracycline.

[0050] Comparative Example 1 This comparative example provides a method for preparing a bismuth halide photocatalyst, which is basically the same as that in Example 1, except that step S3 is not included, i.e., the photocatalyst obtained is BiOCl.

[0051] Comparative Example 2 This comparative example provides a method for preparing a bismuth halide photocatalyst, which is basically the same as that in Example 1, except that step S2 is not included, i.e., the bismuth halide obtained is BiOI.

[0052] Experimental Example 1. X-ray diffraction analysis (XRD) The XRD patterns of the photocatalysts obtained by the preparation methods of Examples 1-4 and Comparative Examples 1-2 were tested, and the test results are as follows: Figure 1-2 As shown.

[0053] XRD analysis was performed on the photocatalyst BiOCl prepared by the methods provided in the embodiments and comparative examples of this application. 1-x I x The crystal structure of BiOCl and BiOI provided in Comparative Examples 1-2 is used as a comparison sample. The test results show that BiOCl and BiOI belong well to the tetragonal phase and are free of impurities. The diffraction peaks at 12.0°, 25.9°, 32.5° and 33.4° correspond to the (001), (101), (110) and (102) planes of the tetragonal phase BiOCl (PDF#82-0485), and the peaks at 29.7°, 31.7°, 45.4° and 55.3° correspond to the (102), (100), (200) and (212) planes of the tetragonal phase BiOI (PDF#73-2062).

[0054] When x is 0.1, in addition to the characteristic peak of BiOCl, there are other peaks in BiOCl. 1-x I x No BiOI characteristic peaks were observed. A weak BiOI characteristic peak appeared near 29.7° when x was 0.2. When x was 0.3 and 0.4, BiOCl… 1-x I x The XRD patterns show characteristic coexistence peaks of BiOI and BiOCl. Furthermore, from... Figure 2 In the magnified image of the mid-range diffraction peaks (2θ = 26°~36°), it can be clearly observed that, compared with pure BiOCl, the peaks corresponding to BiOCl... 1-x I x The diffraction peaks in the (110) plane (x=0.1, 0.2, 0.3, 0.4) shift towards lower angles, indicating that some iodine ions have entered the BiOCl lattice and formed BiOCl. 1-x I x Solid solution. According to Bragg's law of diffraction: , When Cl with a radius of 1.81 Å in the BiOCl lattice - Part of it was affected by I with a larger radius (2.16 Å). - During substitution, the interplanar spacing increases, causing the diffraction angle to shift to lower angles. When the proportion of iodide ions is low (x=0.1), the obtained sample exists entirely in solid solution form. When the proportion of iodide ions exceeds a certain value (x>0.2), except for BiOCl... 1-x I xIn vitro, BiOCl / BiOI complexes can also be observed. (BiOCl) 1-x I x The solid solution is easy to form at room temperature mainly because BiOCl and BiOI have a layered structure, in which halide ions in the lattice are connected by weak van der Waals forces, which makes it easy for halogen atoms to substitute for each other.

[0055] 2. Fourier transform infrared spectroscopy analysis (FT-IR) The FT-IR spectra of the photocatalysts obtained by the preparation methods of Examples 1-4 and Comparative Examples 1-2 were tested, and BiOCl, BiOI, and BiOCl were also analyzed. 1-x I x The FT-IR spectrum of the sample is as follows Figure 3 As shown.

[0056] As can be seen from the figure, the FT-IR spectrum at 1635 cm⁻¹ -1 and 1385 cm -1 There are two absorption peaks nearby, both caused by the bending vibrations of OH bonds, possibly due to the adsorption of water molecules on the catalyst surface. At 1099 cm⁻¹... -1 and 950 cm -1 Two absorption peaks were observed at 529 cm⁻¹, which is due to the stretching vibrations of the COC and C-OH bonds in polyethylene glycol. -1 and 484cm -1 The absorption peaks at these locations are caused by the stretching vibrations of the Bi-O bonds in BiOCl and BiOI, respectively.

[0057] 3. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis The iodine-doped BiOCl photocatalyst BiOCl prepared by the preparation method provided in Example 1 of this application was tested. 0.9 I 0.1 The microstructure of the solid solution, as shown in the test results are as follows: Figure 4 (a)- Figure 4 As shown in (h), in, Figure 4 (a)- Figure 4 (c) is BiOCl 0.9 I 0.1 The SEM image shows that the BiOCl obtained by the method provided in Embodiment 1 of this application... 0.9 I 0.1It is a micro-flower-like hierarchical structure composed of interlaced ultrathin nanosheets with a diameter of 2-3 μm and a thickness of 15 nm. The flower-like hierarchical structure easily exposes more active sites, which helps in the separation of photogenerated charge carriers and the adsorption and transfer of organic pollutants (such as ciprofloxacin). The formation of the flower-like microsphere structure is mainly due to the dispersion and morphology control of polyethylene glycol during sample formation.

[0058] Figure 4 (d) is BiOCl 0.9 I 0.1 The EDS spectrum of BiOCl shows that the test results indicate that BiOCl 0.9 I 0.1 It is composed of four elements: O, Bi, Cl, and I. The elemental distribution diagram is shown below. Figure 4 As shown in (e), it can be seen from the figure that BiOCl 0.9 I 0.1 It is composed of O, Bi, Cl and I elements, and all elements are evenly distributed.

[0059] Figure 4 (f) is BiOCl 0.9 I 0.1 TEM images, Figure 4 (g) is BiOCl 0.9 I 0.1 High-resolution transmission electron microscopy (HR-TEM) images show that BiOCl... 0.9 I 0.1 The solid solution contains two sets of lattice fringes spaced at 0.308 nm and 0.343 nm, which correspond to the (102) lattice plane of tetragonal BiOI and the (101) lattice plane of BiOCl, respectively, indicating that BiOCl... 0.9 I 0.1 The formation of solid solutions.

[0060] Figure 4 (h) represents BiOCl 0.9 I 0.1 The selected area electron diffraction (SEAD) image shows that under continuous bombardment by a high-energy electron beam, BiOCl... 0.9 I 0.1 The SEAD pattern shows diffraction rings, indicating polycrystalline properties and confirming the coexistence of BiOCl and BiOI crystal phases.

[0061] 4. Specific surface area measurement and analysis (BET) The iodine-doped BiOCl photocatalyst BiOCl prepared by the preparation method provided in Example 1 of this application was tested. 0.9 I 0.1 The N2 adsorption-desorption isotherms of BiOCl provided in Comparative Example 1 are shown below. The test results are as follows: Figure 5 and Figure 6 As shown, according to the IUPAC classification, BiOCl and BiOCl 0.9 I 0.1 The sample exhibits a type IV adsorption-desorption isotherm characteristic with an H3 hysteresis loop, indicating a plate-like, slit-like mesoporous structure. BiOCl and BiOCl 0.9 I 0.1 The specific surface area is 19.1 m². 2 / g and 28.5 m 2 / g. Because BiOCl 0.9 I 0.1 It has a micro-flower hierarchical structure, resulting in a larger specific surface area, thereby exposing more active sites, which is beneficial for the separation of photogenerated electrons and holes as well as the adsorption and transfer of organic pollutants.

[0062] 5. X-ray photoelectron spectroscopy (XPS) analysis The iodine-doped BiOCl photocatalyst BiOCl prepared by the preparation method provided in Example 1 of this application was tested. 0.9 I 0.1 XPS spectra, test results are as follows Figure 7 (a)- Figure 7 As shown in (e).

[0063] Figure 7 (a) is the XPS full spectrum. From the figure, it can be seen that BiOCl... 0.9 I 0.1 It is composed of Bi, C, Cl, I and O elements, and contains no other impurities.

[0064] Figure 7 (b) is a high-resolution Bi 4f orbital plot, in which the peaks at 158.11 eV and 163.43 eV can be attributed to Bi 4f, respectively. 7 / 2 and Bi 4f 5 / 2 This indicates that bismuth in BiOCl 0.9 I 0.1 Chinese and Israeli Bi 3+ It exists in the form of.

[0065] Figure 7 (c) is a high-resolution Cl 2p orbital plot. The peaks at 196.78 eV and 198.36 eV in the plot can be attributed to the Cl 2p orbitals of BiOCl, respectively. 3 / 2 and Cl 2p 1 / 2 This indicates that chlorine in BiOCl 0.9 I 0.1 China and Israel Cl - It exists in form.

[0066] Figure 7(d) is a high-resolution I 3d orbital plot. The peaks at 618.00 eV and 629.49 eV in the figure can be attributed to the I 3d orbitals of BiOI, respectively. 3 / 2 and I3d 5 / 2 .

[0067] Figure 7 (e) is a high-resolution O 1s orbital plot. The peaks at 528.93 eV and 531.42 eV in the plot can be attributed to BiOCl. 0.9 I 0.1 Oxygen in the lattice and hydroxyl oxygen adsorbed on the surface.

[0068] XPS also measured BiOCl. 0.9 I 0.1 The surface atomic ratio of Bi4f:Cl2p:O1s:I3d is 6:7:1:1. The higher O content compared to the theoretical value is likely due to the adsorption of O2 and CO2 on the sample surface.

[0069] 6. UV-Vis DRS and bandgap analysis The UV-Vis diffuse reflectance absorption spectra and band gap diagrams of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 of this application were tested, and the test results are as follows: Figure 8-9 As shown.

[0070] Test results show that BiOCl with different chloride-iodine ratios 1-x I x The samples exhibited different visible light absorption ranges. Compared to the BiOCl sample, with increasing iodine content, the BiOCl... 1-x I x As light absorption shifts towards longer wavelengths, the color of the corresponding sample gradually changes from white to orange-red (e.g., ...). Figure 8 (As shown in the illustration). When the molar ratio of Cl / I is 0.9 / 0.1, 0.8 / 0.2, 0.7 / 0.3, and 0.6 / 0.4, BiOCl... 1-x I x The band gap absorption edges of the samples extended to 493 nm, 647 nm, 647 nm and 668 nm, respectively.

[0071] Using the KM formula: , The band gap energy (Eg) values ​​for all samples can be obtained. In the above formula, α is the absorption coefficient, hv is the photon energy, A is the absorption constant, Eg is the band gap energy, and n is the transition exponent. Due to the indirect transition characteristics, the n value of BiOCl is 4, (αhv) 1 / 2 The relationship between hv and hv is shown in the figure below. Figure 9 As shown. BiOCl, BiOCl0.9 I 0.1 BiOCl 0.8 I 0.2 BiOCl 0.7 I 0.3 BiOCl 0.6 I 0.4 The Eg values ​​of BiOI were 3.07 eV, 2.25 eV, 1.72 eV, 1.79 eV, 1.70 eV and 1.78 eV, respectively.

[0072] 7. Schottky diagram analysis The Schottky curves of the photocatalysts provided in Example 1 and Comparative Examples 1-2 of this application were tested, and the test results are as follows: Figure 10-11 As shown.

[0073] For BiOCl 0.9 I 0.1 Mott-Schottky (MS) experiments were performed on BiOCl and BiOI to determine the flat band potential and further obtain the valence band (VB) and conduction band (CB) edges. The experimental results are as follows: Figure 10 As shown, at a frequency of 2.0 kHz, the slope of the MS curve is negative, indicating that BiOCl... 0.9 I 0.1 BiOCl and BiOI are p-type semiconductors. The flat-band potential can be obtained from the following MS equation: .

[0074] Where C and A are the interface capacitance and area, respectively; ε0 and ε are the dielectric constant of free space and the dielectric constant of the semiconductor, respectively; N D It is the number of charge carriers, E and E fb Let k represent the applied electric potential and the surface electric potential, respectively. B Let k represent the Boltzmann constant, and T and e represent the absolute temperature and electric charge, respectively. At room temperature, k... B T / e is approximately 0.026V, which can be ignored. According to... Figure 10 and Figure 11 Extrapolating to C -2 =0,BiOCl 0.9 I 0.1 E of BiOCl and BiOI fb The values ​​can be determined to be 1.73V, 2.49V, and 1.92V (vs. Ag / AgCl). The reversible hydrogen electrode potential (RHE) can be obtained according to the Nernst equation.

[0075] E Ag / AgClThe potential measured in the experiment. E 0 Ag / AgCl The standard potential of Ag / AgCl at 298 K is 0.1976 V. The pH of a 0.1 M Na₂SO₄ aqueous solution is 7. Therefore, the calculations of BiOCl, BiOCl₀.₈I₀.₁, and BiOI are as follows. E RHE ( E fb The values ​​are 3.10 eV, 2.34 eV, and 2.53 eV, respectively. For p-type semiconductors, the flat-band potential is 0.1~0.3V lower than the VB edge potential. When E VB and E fb When the potential difference between them is set to 0.2V, BiOCl 0.9 I 0.1 E of BiOCl and BiOI VB The values ​​are 2.54 eV, 3.30 eV, and 2.73 eV, respectively, according to the following formula: BiOCl 0.9 I 0.1 E of BiOCl and BiOI CB The values ​​obtained are 0.29 eV, 0.23 eV, and 0.95 eV. 8. Photocatalytic performance test The photocatalytic degradation effects of the photocatalysts provided in Examples 1-4 and Comparative Examples 1-2 on ciprofloxacin (CIP) were tested.

[0076] The photocatalytic degradation of BiOCl by CIP (20 mg / L) under visible light irradiation (λ≥400 nm) was evaluated. 1-x I x The photocatalytic degradation efficiency of solid solutions was compared with that of pure BiOCl and BiOI provided in the comparative example. The test results are as follows: Figure 12 As shown. Test results indicate that, without any photocatalyst (blank), the self-degradation rate of CIP under visible light is 4%, which is negligible. Before light irradiation, the photocatalytic reaction system was placed in the dark and stirred for 30 minutes to achieve adsorption-desorption equilibrium. From Figure 12 It can be seen that BiOCl and BiOCl 1-x I x BiOCl exhibits strong adsorption capacity for CIP. It shows the strongest adsorption capacity, with an adsorption rate of 55% for CIP. 0.9 I 0.1 BiOCl 0.8 I 0.2 BiOCl 0.7 I0.3 BiOCl 0.6 I 0.4 The adsorption rates of CIP by BiOCl and BiOI were 40%, 24%, 14%, 28%, and 27%, respectively. The strong adsorption capacity of BiOCl is likely due to the opposite charge between it and CIP, and the strong electrostatic adsorption between them. After 70 minutes of irradiation, the degradation rate of CIP by BiOCl was 84.4%, while that by BiOCl... 0.9 I 0.1 The photocatalytic degradation rate of CIP was 94.1%. However, BiOCl... 0.8 I 0.2 BiOCl 0.7 I 0.3 BiOCl 0.6 I 0.4 Besides adsorption, the BiOI sample exhibited very low photocatalytic degradation activity for CIP. The degradation curve of pure BiOI showed that the CIP degradation rate was entirely due to adsorption, with desorption occurring later. This is mainly because BiOI has a very narrow band gap, which allows photogenerated carriers to recombine rapidly and easily during irradiation. With the development of BiOCl... 1-x I x The increased substitution rate of iodide ions not only leads to the formation of solid solutions but also results in the presence of more BiOI, which reduces their photocatalytic activity.

[0077] To visually compare photocatalytic activity, the Langmuir Hinshelwood kinetic model was used: , The apparent reaction rate constant (k) was fitted in the above formula, where k and t are the reaction rate constant and irradiation time, respectively. C0 and C are the CIP concentrations at irradiation times t=0 and t, respectively. According to the above equation, the higher the value of k, the better the photocatalytic activity. Figure 13 As can be seen, the change in CIP concentration with irradiation reaction time follows a pseudo-first-order kinetic. (BiOCl) 0.9 I 0.1 The rate constant is the highest (0.038 min). -1 It is twice that of BiOCl (0.018 min). -1 To eliminate the influence of specific surface area on degradation efficiency, BiOCl and BiOCl 0.9 I 0.1 The rate constant per unit specific surface area was calculated to be 0.00068 g•min. -1 m 2 and 0.0013 g•min -1 m 2 This indicates that BiOCl 0.9 I0.1 Excellent photocatalytic efficiency does not depend entirely on its large specific surface area.

[0078] Figure 14 The addition of BiOCl provided in Example 1 is shown. 0.9 I 0.1 The UV-Vis absorption spectra of CIP under photocatalysis in the dark and under visible light irradiation are shown in the figure. As can be seen from the figure, the maximum absorption peak of CIP is located at 276 nm, and this peak gradually decreases with increasing irradiation time. During the degradation process, a blue shift can be observed at the maximum absorption wavelength, indicating that chemical bonds in CIP break and new intermediate products are generated during photocatalytic degradation.

[0079] To further study BiOCl 0.9 I 0.1 The recyclability was assessed by recovering the photocatalyst powder after the photocatalytic reaction through static precipitation, removal of the supernatant, and drying. Five repeated photocatalytic experiments were then conducted on the recovered catalyst powder, and the test results are as follows: Figure 15 As shown. After 5 cycles of experimentation, BiOCl... 0.9 I 0.1 The fact that the photocatalyst can still maintain excellent photocatalytic degradation efficiency indicates that it has excellent photochemical stability and good prospects for practical application.

[0080] To further compare BiOCl 0.9 I 0.1 The visible light photocatalytic activity of the solid solution and BiOCl was investigated using a xenon lamp with a 420 nm cutoff filter as the visible light source. The photocatalytic degradation effect of the two photocatalysts on CIP was further studied. The test results are as follows: Figure 16 As shown, the test results indicate that after 50 minutes of light irradiation, BiOCl achieved a degradation rate of 62.7% for CIP, primarily due to adsorption. In contrast, BiOCl... 0.9 I 0.1 The degradation rate of CIP was 87.6%, indicating that BiOCl... 0.9 I 0.1 It exhibits excellent visible light photocatalytic activity in the visible light region with a relatively large wavelength.

[0081] Considering the practical feasibility of using sunlight for wastewater treatment, we investigated the photocatalytic degradation of CIP by BiOCl0.9I0.1 under simulated sunlight. Furthermore, we also studied the photocatalytic degradation of TC and RhB under simulated sunlight and visible light, respectively. Figure 17As shown, the degradation rate of CIP under simulated sunlight (SS) was significantly higher than that under visible light. After 70 minutes of illumination, the CIP degradation rate reached 97.5%. Under visible light (VL) and simulated sunlight for 30 minutes, the degradation rates of TC reached 98.0% and 96.7%, respectively. For RhB, BiOCl0.9I0.1 exhibited an adsorption rate of 60%–70%. After 4 minutes of simulated sunlight irradiation, the RhB degradation rate reached 99.5%. After 3 minutes of visible light irradiation, the RhB solution achieved a degradation rate of 99.6%. 9. Photocatalytic mechanism analysis: To determine the effect of different reactant species on the photocatalytic degradation of CIP, p-benzoquinone (BQ), isopropanol (IPA), and potassium iodide (KI) were used as scavengers to catalyze the degradation of BiOCl catalyst. 0.9 I 0.1 A trapping experiment was conducted to eliminate the scavenger and BiOCl. 0.9 I 0.1 The effect of scavenging agent on CIP solution adsorption was investigated by adding the scavenging agent to the CIP solution at different stages and stirring in the dark for 60 minutes. Figure 18 As shown, under dark conditions, various active species scavengers were added to the reaction system and stirred for 30 minutes (Stage I). A decrease of approximately 10%–16% in the CIP solution concentration was observed. When IPA was used as the scavenger, the CIP solution concentration decreased significantly, indicating that IPA had the most significant adsorption effect on CIP. Adding BiOCl to the system... 0.9 I 0.1 After stirring for 30 minutes (Stage II), the concentration of the CIP solution containing BQ, KI, and IPA decreased significantly, and the solution system reached adsorption-desorption equilibrium. Simultaneously, a comparative study was conducted on the catalyst system without a scavenger. Without a scavenger, BiOCl... 0.9 I 0.1 The adsorption rate of CIP reached 40.3% under dark conditions, indicating that the presence of the scavenger affected BiOCl. 0.9 I 0.1 The absorption capacity of BiOCl was determined. After the system reached adsorption-desorption equilibrium, the photocatalytic system was exposed to visible light (λ≥400nm) for 70 minutes, and the absorbance at the maximum absorption wavelength was measured to obtain the BiOCl content. 0.9 I 0.1 CIP photocatalytic degradation rate in the presence of different scavengers (stage III).

[0082] Figure 19 Various scavengers were shown to be effective against BiOCl. 0.9 I 0.1The histogram shows the effect of adsorption on CIP degradation. When KI is used as the trapping agent, the CIP degradation rate reaches only 23.7%, indicating that holes play a crucial role in this photocatalytic system. When BQ is used as the trapping agent, the CIP degradation rate significantly decreases to 15.0%. However, previous studies have shown that BQ can react with ·OH. Therefore, the above results showing that CIP degradation is inhibited after the addition of BQ alone cannot effectively confirm the effect of ·O2. - The presence of [a specific substance, likely O2] is also noted. Furthermore, BQ is readily oxidized under air and light conditions, and the intermediate products generated may have adsorption properties for pollutants. To further verify whether this system generates O2... - We quantitatively determined its yield by capturing ·O2 under visible light using nitrotetrazole blue (NBT). - By observing the formation of the blue formazan product, we can qualitatively determine the presence of O2. - The presence of O2 was observed. However, contrary to the results of the BQ capture experiment, no obvious blue product was observed under visible light irradiation, and the absorbance of the NBT solution at 259 nm remained essentially unchanged, indicating that the catalyst did not produce O2 under visible light irradiation. - Active species. We believe that NBT can be used to quantitatively detect O2. - The method described above is more accurate, while experiments using BQ as a trapping agent are highly unreliable. Therefore, ·O2 - CIP is not a major active species in this photocatalytic process. When IPA is used as a capture agent, the photocatalytic degradation rate of CIP decreases only slightly, which may indicate that ·OH is not the main active species. However, Wang L. et al. found that traditional alcohol-based ·OH detection methods are unreliable and can even produce misleading results. To accurately verify the presence of ·OH, a terephthalic acid (TA) fluorescent probe method was used to capture and quantitatively detect the ·OH generated in the reaction system. Figure 20 As shown, significant fluorescence peaks were observed at 425 nm after 30 and 60 minutes of illumination. The fluorescence intensity gradually increased with increasing illumination time, indicating the generation of a large amount of ·OH under visible light. Fluorescence detection experiments using TA to capture ·OH confirmed that IPA cannot act as a ·OH scavenger. ·OH is the main active species in this photocatalytic reaction system. The photocatalytic degradation reaction is shown below.

[0083] ; ; BiOCl, BiOI and BiOCl 0.9 I 0.1 The band structure and photocatalytic degradation mechanism diagram are shown below. Figure 21As shown, due to the wide bandgap of BiOCl (Eg=3.26eV), photogenerated carriers cannot transition from VB to CB under visible light irradiation (λ>400nm). Although BiOCl achieves a total removal rate of 82.7% for CIP, the actual photocatalytic degradation rate is only 27.7%, with 55% attributed to adsorption. Furthermore, as the previous test results show, under irradiation in the visible light region at larger wavelengths (λ>420nm), the photocatalytic efficiency of BiOCl is significantly lower than that of BiOCl. 0.9 I 0.1 Photocatalyst. Although BiOI has a relatively narrow band gap (1.78 eV), it does not exhibit photocatalytic activity for CIP, mainly due to the faster recombination rate of photogenerated carriers.

[0084] BiOCl 0.9 I 0.1 With a band gap of 2.25 eV, it can readily generate photogenerated carriers under visible light (λ>400 nm) illumination. These photogenerated electrons on CB and holes on VB rapidly migrate to BiOCl. 0.9 I 0.1 The surface of the photocatalyst. However, due to the conduction band edge potential (0.29 eV) relative to O2 / The redox potential of O2- (-0.33 eV vs. NHE) is corrected, causing the electrons that transition to CB to be unable to reduce the O2 molecule to a superoxide radical (·O2). - This finding is consistent with the results of the aforementioned NBT capture experiments, indicating that superoxide radicals are not the primary reactive species.

[0085] The valence band potential is 2.54 eV, which is more positive than ·OH / H2O (1.99 eV). Therefore, photogenerated holes can oxidize H2O into hydroxyl radicals, thus degrading pollutants. Photogenerated holes have a strong oxidizing ability and can directly oxidize and degrade pollutants.

[0086] BiOCl 0.9 I 0.1 The suitable band gap structure of solid solution photocatalysts not only enhances their adsorption capacity for visible light but also effectively separates and transfers photogenerated carriers. This is the main factor leading to their high photocatalytic efficiency. Furthermore, BiOCl with a micro-flower-like hierarchical structure assembled from ultrathin nanosheets... 0.9 I 0.1 Solid solutions exhibit good dispersibility and a larger specific surface area, easily exposing more active sites, which is beneficial for the separation of photogenerated carriers and the adsorption and transfer of pollutants. Therefore, BiOCl... 0.9 I 0.The enhanced photocatalytic activity of the solid solution can be attributed to improved visible light absorption, efficient separation and transfer of photogenerated charge carriers, and the synergistic effect of the flower-like hierarchical structure assembled from ultrathin nanosheets. Holes and superoxide radicals are BiOCl... 0.9 I 0.1 The main active substances in solid solution photocatalytic reactions.

[0087] 10. Electrochemical performance testing Generally speaking, the separation and transfer efficiency of photogenerated carriers has a significant impact on the photocatalytic performance of semiconductors. The separation and transfer efficiency of photogenerated carriers were evaluated by measuring transient photocurrent response, electrochemical impedance spectroscopy (EIS), and photoluminescence spectroscopy (PL).

[0088] Test results are as follows Figure 22-24 As shown, from Figure 22 As can be seen from this, BiOCl 0.9 I 0.1 The higher photocurrent response compared to BiOCl indicates better transfer and migration of photogenerated carriers. Figure 23 As can be seen from this, BiOCl 0.9 I 0.1 The arc radius is smaller than that of BiOCl, indicating that BiOCl 0.9 I 0.1 It has a stronger charge transfer capability. BiOCl and BiOCl 0.9 I 0.1 The PL emission spectrum at an excitation wavelength of 365 nm is as follows: Figure 24 As shown, BiOCl 0.9 I 0.1 The peak intensity near 417 nm is much weaker than that of pure BiOCl, indicating that BiOCl 0.9 I 0.1 It has the lowest photogenerated electron-hole pair recombination efficiency, which means that BiOCl 0.9 I 0.1 It has a longer excitation lifetime and higher separation efficiency.

[0089] In summary, the embodiments of this application synthesized BiOCl with a micro-flower-like morphology at room temperature via a simple and mild one-step ion exchange method. 1-x -I x A solid solution photocatalyst was developed, and its photocatalytic performance under visible light was investigated. Test results show that the BiOCl provided in Example 1 of this application… 0.9 I 0.1 The photocatalyst exhibited the best photodegradation performance for pollutants such as CIP, achieving a degradation rate of 94.1% for CIP after 70 minutes of illumination. (BiOCl) 0.9 I 0.1(0.038min) -1 The rate constant of is twice that of pure BiOCl. 0.9 I 0.1 The solid solution also exhibited excellent photochemical stability after five cycles of CIP degradation. Furthermore, BiOCl... 0.9 I 0.1 It also exhibits excellent removal efficiency for TC and RhB. BiOCl 0.9 I 0.1 The enhanced photocatalytic activity of the solid solution can be attributed to the synergistic effect of improved visible light absorption, efficient separation and transfer of photogenerated charge carriers, and the micro-flower-like hierarchical structure assembled from ultrathin nanosheets. Capture experiments and terephthalic acid fluorescent probe experiments show that h + and Hydroxyl radicals play a dominant role in the degradation of CIP, and a possible photocatalytic mechanism has been proposed. The preparation method provided in this application is simple, energy-efficient, environmentally friendly, and easy to scale up.

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an iodine-doped BiOCl photocatalyst, characterized in that: The preparation method includes the following steps: S1. Polyethylene glycol is mixed with deionized water to prepare a premixed solution. A water-soluble bismuth salt is added to the premixed solution and stirred evenly at room temperature to obtain a first mixed solution. The mass percentage of the water-soluble bismuth salt in the first mixed solution is 2-30 wt%. S2. Add water-soluble chloride salt to the first mixed solution and stir evenly at room temperature to obtain a second mixed solution, wherein the molar ratio of the water-soluble chloride salt to the water-soluble bismuth salt is 0.6-0.99:1; S3. Add water-soluble iodine salt to the second mixed solution and stir evenly at room temperature to obtain a preproduct. The molar ratio of the water-soluble iodine salt to the water-soluble bismuth salt is 0.01-0.4:

1. S4. Separate, wash, and dry the precipitate in the preproduct.

2. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 1, characterized in that, The water-soluble bismuth salt is Bi(NO3)3·5H2O or bismuth acetate.

3. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 1 or 2, characterized in that, The water-soluble chloride salt is potassium chloride or sodium chloride.

4. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 3, characterized in that, The water-soluble iodized salt is potassium iodide or sodium iodide.

5. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 4, characterized in that, The molecular weight of the polyethylene glycol is 200-20000.

6. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 5, characterized in that, In the premixed solution, the mass percentage of polyethylene glycol is 0.2-1 wt%.

7. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 6, characterized in that, In step S1, the stirring time at room temperature is 30-120 min; in step S2, the stirring time at room temperature is 30-120 min; in step S3, the stirring time at room temperature is 30-120 min.

8. The method for preparing the iodine-doped BiOCl photocatalyst according to claim 7, characterized in that, In step S4, the drying process is vacuum drying, with a temperature of 40-60℃ and a drying time of 6-8 hours.

9. An iodine-doped BiOCl photocatalyst, characterized in that, The iodine-doped BiOCl photocatalyst is prepared by the method described in any one of claims 1-8.

10. The application of the iodine-doped BiOCl photocatalyst as described in claim 9 in the photocatalytic degradation of organic pollutants in wastewater, wherein the organic pollutant is at least one of ciprofloxacin, rhodamine B, and tetracycline.

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