An Ag / WS2 / BiOI nanophotocatalyst containing oxygen vacancies and its preparation method

Abstract

This invention relates to the field of nano-photocatalytic materials, specifically to an Ag / WS2 / BiOI nano-photocatalytic material containing oxygen vacancies and its preparation method. The invention employs a stirring-precipitation method to prepare an oxygen-vacancy WS2 / BiOI heterojunction, and then loads Ag onto WS2 / BiOI via a photoreduction method to form an Ag / WS2 / BiOI heterojunction with excellent photocatalytic performance. Experimental results show that the Ag / WS2 / BiOI heterojunction exhibits the best removal effect on 80 mg / L Lanazol Red 5B after 20 minutes under simulated sunlight, with a removal rate of 88.24%, which is 1.81, 9.40, and 1.39 times that of pure BiOI, WS2, and WS2 / BiOI photocatalytic materials, respectively.

Description

Technical Field

[0001] This invention relates to the field of nanophotocatalytic materials, and more particularly to an Ag / WS2 / BiOI nanophotocatalytic material containing oxygen vacancies and its preparation method. Background Technology

[0002] Currently, dye wastewater contains various toxic and recalcitrant components (such as aromatic amines and heavy metals), which can easily poison aquatic organisms, disrupt the food chain, and even increase the risk of cancer and birth defects in humans. Simultaneously, the high chroma and chemical stability of dyes reduce the self-purification capacity of water bodies and pollute soil and groundwater. Traditional water treatment technologies (such as coagulation and adsorption) have limitations in dye removal, including low efficiency, high energy consumption, and secondary pollution. Photocatalysis technology, with its advantages of directly utilizing solar energy to drive reactions and eliminating secondary pollution, is considered one of the effective ways to solve this problem. However, traditional single photocatalytic materials are often limited by problems such as high photogenerated carrier recombination rates and narrow visible light response ranges, severely restricting their practical application. Therefore, developing stable and efficient novel photocatalytic materials has become an important research direction.

[0003] In recent years, bismuth-based semiconductor photocatalytic materials have attracted widespread attention in the field of photocatalysis due to their excellent light absorption performance and efficient carrier separation capability. Bismuth oxyiodide (BiOI), a typical bismuth-based material, exhibits a unique tetragonal layered crystal structure composed of alternating layers of [I-Bi-O-Bi-I] structural units. This layered structure provides an efficient channel for the migration of photogenerated carriers, significantly promoting the separation of electron-hole pairs. From a semiconductor perspective, BiOI belongs to the p-type semiconductor category, with a relatively low Fermi level. This characteristic enables it to exhibit unique charge transport and redox capabilities in photocatalytic reactions. However, BiOI also suffers from drawbacks such as a limited number of active sites, easy aggregation of micro / nano particles, and difficulty in recycling, which limits its photocatalytic performance. Generally, heterostructure construction and noble metal deposition can improve the photocatalytic performance of materials. Tungsten disulfide (WS2), a typical transition metal chalcogenide, possesses a unique two-dimensional layered structure, a large specific surface area, and high carrier mobility, and is widely used in the field of photocatalysis. Oxygen vacancy technology, which optimizes the bandgap of semiconductors and promotes the effective separation of photogenerated electrons and holes, has been widely studied and adopted. Oxygen vacancy technology has a significant impact on the electronic structure and physical properties of semiconductors, reducing the bandgap and improving visible light response. Furthermore, it can generate a large number of local electrons on the surface of photocatalytic materials, increasing the number of active sites for adsorption and photocatalytic reactions. Summary of the Invention

[0004] To address the issues of low visible light utilization, low photogenerated electron-hole separation efficiency, and easy recombination in photocatalytic materials, this invention provides a method for preparing Ag / WS2 / BiOI nanophotocatalytic materials. Ag is loaded onto WS2 / BiOI via a photoreduction method to form an Ag / WS2 / BiOI heterojunction with good photocatalytic performance.

[0005] The technical solution adopted in this invention is: a method for preparing Ag / WS2 / BiOI nanophotocatalytic materials containing oxygen vacancies, mainly including the following steps:

[0006] S1. Preparation of binary oxygen vacancy WS2 / BiOI heterojunctions using a stirring-precipitation method:

[0007] WS2 powder was dissolved in an ethanol solution and subjected to ultrasonic treatment to obtain uniformly dispersed WS2 nanosheets. Then, a certain amount of WS2 nanosheets was added to a solution of ethylene glycol and deionized water to obtain solution A. Bi(NO3)3•5H2O was added to solution A and stirring was continued. Thiourea was then added and stirring was continued. KI was added, followed by glacial acetic acid solution. Stirring and reaction were continued. After the reaction was completed, a WS2 / BiOI heterojunction precipitate was obtained. The obtained heterojunction precipitate was washed, dried, and ground into powder for later use.

[0008] S2. Preparation of Ag / WS2 / BiOI nano-photocatalytic materials by photoreduction method:

[0009] The WS2 / BiOI heterojunction powder obtained in step S1 was added to deionized water and subjected to ultrasonic treatment to obtain solution B. The prepared AgNO3 solution was added dropwise to solution B and stirred to obtain solution C. Solution C was placed under a xenon lamp for irradiation, and then solution C was centrifuged and dried to obtain the Ag / WS2 / BiOI photocatalytic material.

[0010] As a preferred embodiment, the step of preparing solution A in step S1 is as follows: 0.2 g to 0.3 g of WS2 powder is dissolved in 80 ml to 120 ml of 70% ethanol solution, ultrasonically treated for 10 hours, and dried to obtain WS2 nanosheets. Then, 0.02 g to 0.04 g of the prepared WS2 nanosheets are weighed and added to 80 ml to 120 ml of a solution with a volume ratio of 50% ethylene glycol and 50% deionized water to obtain solution A.

[0011] As a preferred embodiment, in step S1, 0.4g to 0.5g of Bi(NO3)3•5H2O is added to solution A and stirred for 10 minutes. Then, 10ml to 30ml of 1mol / L thiourea solution is added and stirred for 10 to 15 minutes. After that, 0.1g to 0.2g of KI is added, followed by 80ml to 120ml of 99% glacial acetic acid solution. Stirring is continued for 1 hour.

[0012] As a preferred embodiment, in step S1, the precipitate after the reaction is completed is washed three times each with deionized water and anhydrous ethanol, and then dried in a drying oven at 80°C to 100°C.

[0013] As a preferred embodiment, in step S2, the preparation step of solution B is as follows: 0.4g to 0.6g of WS2 / BiOI heterojunction powder is added to 30ml of deionized water to obtain a suspension, and the suspension is continuously sonicated for 1 hour to form a uniform suspension.

[0014] As a preferred embodiment, in step S2, the concentration of the prepared AgNO3 solution is 3.1 mg / ml to 3.5 mg / ml, and the preparation volume is 4 ml to 6 ml.

[0015] As a preferred embodiment, in step S2, the treatment step of solution C is as follows: after stirring solution C on a magnetic stirrer for 2 to 3 hours, place the fully adsorbed solution C under a 350W xenon lamp for 2 to 3 hours.

[0016] An Ag / WS2 / BiOI nanophotocatalyst material containing oxygen vacancies was prepared using the method described above.

[0017] The beneficial effects of this invention are:

[0018] This invention employs a stirring-precipitation method to prepare oxygen-vacancy WS2 / BiOI heterojunctions. Ag is then loaded onto WS2 / BiOI via photoreduction to form Ag / WS2 / BiOI heterojunctions with excellent photocatalytic performance. Experimental results show that the Ag / WS2 / BiOI heterojunction exhibits the best removal effect on 80 mg / L Lanazol Red 5B after 20 minutes under simulated sunlight, achieving a removal rate of 88.24%, which is 1.81, 9.40, and 1.39 times that of pure BiOI, WS2, and WS2 / BiOI photocatalytic materials, respectively.

[0019] This invention prepares BiOI containing oxygen vacancies by introducing thiourea and glacial acetic acid. The formation of oxygen vacancies is beneficial to improving the photocatalytic performance of the material.

[0020] For Ag / WS2 / BiOI heterojunctions, the band gap of BiOI is approximately 2.2 eV, and the band gap of AgBiO3 is approximately 0.8 eV. They can form staggered Z-shaped heterojunctions, which is beneficial for the rapid separation of photogenerated electron-hole pairs and improves the photocatalytic performance of the material.

[0021] This invention combines the advantages of two-dimensional materials to construct an Ag / WS2 / BiOI heterojunction. The introduction of WS2 nanosheets and the SPR effect of Ag enhance visible light absorption and promote charge separation and transfer. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The XRD patterns of the photocatalytic materials in Example 1 and the comparative examples are shown below.

[0024] Figure 2 The SEM images of Example 1 and each comparative example are shown below;

[0025] Figure 3 XPS graphs of Example 1 and each comparative example;

[0026] Figure 4 The EDS-mapping spectrum of Example 1;

[0027] Figure 5 The degradation diagrams of Lanazon Red 5B by the photocatalytic materials in Example 1 and the comparative examples are shown.

[0028] Figure 6 The degradation spectra of different pollutants by the photocatalytic material in Example 1 are shown.

[0029] Figure 7 The image shows the free radical capture experiment spectrum of the photocatalytic material prepared in Example 1. Detailed Implementation

[0030] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0031] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," or "the," etc., used in this patent application specification do not express a quantity limitation, but rather indicate the presence of at least one; terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function.

[0032] Example 1: Ag / WS2 / BiOI photocatalyst material with a mass fraction of 2wt%

[0033] An Ag / WS2 / BiOI nanophotocatalytic material containing oxygen vacancies, wherein the mass fraction of the Ag / WS2 / BiOI heterojunction is 2wt%, is prepared by the following steps:

[0034] Preparation of S1 and oxygen vacancy WS2 / BiOI:

[0035] A binary oxygen-vacancy WS2 / BiOI heterojunction was prepared using a stirring-precipitation method. First, 0.3 g of WS2 powder was dissolved in 100 mL of 70% ethanol solution, sonicated for 10 h, and then dried to obtain WS2 nanosheets. Then, 0.035 g of WS2 nanosheets were added to 100 mL of a solution containing 50% ethylene glycol and 50% deionized water (v / v), and stirred for 10 min to obtain solution A. 0.482 g of Bi(NO3)3•5H2O was added to solution A, and stirring continued for 10 min. Subsequently, 20 mL of a 1 mol / L thiourea solution was added, and stirring continued for 10 min, followed by the addition of 0.165 g of KI. Next, 100 mL of a 99% glacial acetic acid solution was added, and stirring continued for 1 h. After precipitation, the mixture was centrifuged and washed three times with deionized water and anhydrous ethanol, respectively. Finally, it was dried at 100 °C to obtain the WS2 / BiOI heterojunction, denoted as WB.

[0036] Preparation of S2, Ag / WS2 / BiOI:

[0037] A ternary Ag / WS2 / BiOI heterojunction was prepared using a photoreduction method. 0.5 g of the binary WS2 / BiOI heterojunction was added to 30 mL of deionized water and sonicated for 1 h to ensure complete dispersion; this solution was designated as solution B. 5 mL of a 3.15 mg / mL AgNO3 solution was prepared. The AgNO3 solution was added dropwise to solution B to obtain solution C, which was then stirred on a magnetic stirrer for 2 h. The fully adsorbed solution C was then irradiated under a 350 W xenon lamp for 2 h. After centrifugation and drying, a 2 wt% Ag / WS2 / BiOI photocatalytic material was synthesized, designated as AWB.

[0038] Comparative Example 1: BiOI Sample

[0039] Add 0.482 g of Bi(NO3)3•5H2O to 100 mL of a solution containing 50% ethylene glycol and 50% deionized water (v / v), and continue stirring for 10 min. Then add 20 mL of 1 mol / L thiourea and continue stirring for 10 min, followed by the addition of 0.165 g of KI. Next, add 100 mL of 99% glacial acetic acid solution and continue stirring for 1 h to obtain BiOI.

[0040] Comparative Example 2: WS2 Sample

[0041] 0.3 g of WS2 powder was dissolved in 100 mL of ethanol / water (70% / 30%), sonicated for 10 h and then dried to obtain WS2 nanosheets.

[0042] Comparative Example 3: WS2 / BiOI heterojunction

[0043] The difference between Comparative Example 3 and Example 1 is that only step S1 is used to prepare the desired Comparative Example 3. The specific steps are as follows:

[0044] First, 0.3 g of WS2 powder was dissolved in 100 mL of 70% ethanol solution, sonicated for 10 h, and then dried to obtain WS2 nanosheets. Then, 0.035 g of WS2 nanosheets were added to 100 mL of a solution of 50% ethylene glycol and 50% deionized water (v / v), and stirred for 10 min. Next, 0.482 g of Bi(NO3)3•5H2O was added to the mixture, and stirring continued for 10 min. Then, 20 mL of a 1 mol / L thiourea solution was added, and stirring continued for 10 min, followed by the addition of 0.165 g of KI. Then, 100 mL of a 99% glacial acetic acid solution was added, and stirring continued for 1 h. After precipitation, the mixture was centrifuged and washed three times with deionized water and anhydrous ethanol, respectively. Finally, it was dried at 100 °C to obtain a WS2 / BiOI heterojunction, denoted as WB.

[0045] Performance testing:

[0046] The photocatalytic materials prepared in the above embodiments and comparative examples were characterized and tested for photocatalytic degradation performance. The specific test items are as follows:

[0047] 1. Phase structure: The phase structure was analyzed using X-ray diffraction. Detailed test results are available in [link to relevant documentation]. Figure 1 .

[0048] The XRD pattern of the sample is as follows Figure 1 As shown, pure BiOI in 2 The diffraction peaks at 29.65°, 31.66°, 45.38°, 55.15°, 66.12°, and 74.09° correspond to the (012), (110), (200), (212), (220), and (302) crystal planes, respectively, consistent with the tetragonal crystal form of BiOI (JCPDS:10-0445). Pure WS2 at 2 The diffraction peaks at 14.32° and 28.88° correspond to the (002) and (004) crystal planes (JCPDS:08-0237), confirming the hexagonal structure of WS2. In the WS2 / BiOI heterojunction, the characteristic diffraction peaks are similar to those of BiOI, and the (002) diffraction peak of WS2 is clearly visible, indicating the successful synthesis of the WS2 / BiOI heterojunction. In Ag / WS2 / BiOI, no characteristic diffraction peaks of Ag were clearly observed, possibly due to the low Ag loading. Furthermore, no other impurity peaks appeared in the spectrum, indicating the successful synthesis of the high-purity Ag / WS2 / BiOI sample.

[0049] The above phase structure analysis results show that the Ag / WS2 / BiOI heterojunction photocatalytic material was successfully synthesized in the embodiments of the present invention.

[0050] 2. Morphology and Structure: The surface morphology of the catalyst material was observed using field emission scanning electron microscopy. Detailed test results are available in [link to relevant documentation]. Figure 2 .

[0051] Figure 2 SEM images of BiOI, WS2, and Ag / WS2 / BiOI heterojunctions. Figure 2 (a) The pure BiOI sample exhibits a flower-like structure formed by the interlocking and stacking of nanosheets. Figure 2 (a) The nanosheets have smooth surfaces and a diameter of approximately 2-3 μm. WS2 exhibits a sheet-like structure with a diameter of approximately 2-5 μm. Figure 2 (b) In the ternary Ag / WS2 / BiOI heterojunction, sheet-like WS2 is scattered on the flower-like BiOI surface. At the same time, Ag is observed to be scattered on WS2 and BiOI in the form of nanoparticles, which confirms that Ag and WS2 / BiOI have good interfacial contact, which is conducive to the interfacial reaction.

[0052] 3. Phase structure: XPS was used to analyze the elemental composition and valence states of the sample surface. See attached table for detailed test results. Figure 3 .

[0053] Figure 3 Strong I3d and Bi4f peaks and a relatively weak O1s peak were detected in the full spectrum of pure BiOI. W4f, S2p, Ag3d, I3d, Bi4f and O1s were detected in the ternary composite material, further confirming the successful synthesis of AWB heterojunction.

[0054] Fitting the high-resolution spectra of the elements, such as Figure 3 As shown in (af), all binding energies were calibrated using the C1s peak at the binding energy of 284.8 eV. Figure 3 In (a), the binding energy exhibits two characteristic peaks at 164.80 eV and 159.50 eV, corresponding to Bi4f, respectively. 5 / 2 Bi4f 7 / 2 Electron orbitals indicate that BiOI contains Bi 3+ The existence of. Figure 3 Of the three characteristic peaks appearing in (b), the peak corresponding to the Bi-O bond has a binding energy of 530.45 eV. The other two peaks are located at 532.24 eV and 534.00 eV, which may be related to hydroxyl groups and water adsorbed on the surface. Figure 3 In (c), the characteristic peaks of 619.55 eV and 631.02 eV correspond to I3d, respectively. 5 / 2 and I3d 3 / 2 . Figure 3 In (d), the characteristic peaks appear at binding energies of 33.01 eV and 35.15 eV, indicating the presence of WS2 in the sample. Figure 3 In (e), the characteristic peaks of S and Bi are merged together, but this also proves the presence of S in the synthesized sample. Figure 3 In (f), the characteristic peaks at binding energies of 368.78 eV and 374.78 eV correspond to Ag3d. 3 / 2 and Ag3d 5 / 2 The binding energy difference between the two peaks is 6.0 eV, indicating the presence of zero-valent silver.

[0055] 4. Figure 4 The image shows the EDS-mapping pattern of the photocatalytic material in Example 1.

[0056] As shown in the figure, Bi, O, I, S, W, and Ag are uniformly distributed on the surface of the heterojunction, indicating that the synthesized material is composed of BiOI, WS2, and Ag, further proving the successful preparation of AWB.

[0057] 5. Figure 5The photocatalytic degradation spectra of Lanazon Red 5B by the photocatalytic materials in each embodiment and comparative example are shown.

[0058] Lanazon Red 5B is a common reactive dye often used for dyeing protein fibers such as wool and silk. However, its wastewater discharge is causing increasingly serious pollution to rivers. Therefore, this experiment tested the photocatalytic performance of synthesized samples under simulated sunlight conditions, using Lanazon Red 5B as the target pollutant. Figure 5 (b) To simulate the degradation performance of Lanazol Red 5B by different catalytic materials under sunlight. The control experiment showed that the photodegradation rate of Lanazol Red 5B was low within 50 minutes of dark reaction with Ag / WS2 / BiOI heterojunction, indicating that the process was mainly photocatalytic degradation. At the same time, in the absence of catalytic materials, i.e., the blank control, the photodegradation efficiency of Lanazol Red 5B was also relatively low, but it still degraded by 20.68%, indicating that Lanazol Red 5B undergoes some decomposition under simulated sunlight. Figure 5 (a) The degradation efficiencies of pure BiOI, WS2, and WS2 / BiOI for Lanazon Red 5B solution within 20 minutes were only 48.78%, 9.39%, and 63.69%, respectively, indicating relatively weak photocatalytic activity. For the Ag / WS2 / BiOI heterostructure, the best degradation efficiency was observed in the photocatalytic degradation experiment, reaching 88.24%, which was 1.81, 9.40, and 1.39 times that of pure BiOI, WS2, and WS2 / BiOI, respectively. The enhanced photocatalytic activity is due to the synergistic effect between the heterojunction and noble metal deposition, which improves the separation efficiency of photogenerated carriers. Further observation of the photocatalytic degradation process of Lanazon Red 5B by the Ag / WS2 / BiOI heterojunction under simulated sunlight was conducted using real-time monitoring of UV-Vis absorption spectroscopy. Figure 5 As shown in (c), the results indicate that the characteristic absorption peak (529 nm) of Lanazol Red 5B gradually weakens with increasing reaction time, confirming that the concentration of Lanazol Red 5B gradually decreases. Furthermore, this can be confirmed by a pseudo-first-order kinetic model (ln(C0 / C...). t Further research on photocatalytic activity will be conducted using the formula kt. For example... Figure 5 As shown in (d), the kinetic rate constant (k) of the Lanners Red 5B heterojunction is approximately 0.08866 min. -1 The values ​​were 3.87, 69.27, and 2.33 times higher than those of pure BiOI, WS2, and WB, respectively.

[0059] 6. Figure 6 The degradation spectra of different pollutants by the photocatalytic material prepared in Example 1 are shown.

[0060] Figure 6 (a), Figure 6As shown in (b), when Lanazor Red 5B and methylene blue coexist, the adsorption of the mixed solution is enhanced and the degradation is inhibited, with a Lanazor Red 5B removal rate of 80.93%. This may be due to the competition between organic pollutants and the active species. Figure 6 As shown in (c), the photocatalytic degradation rates of Lanazor Red 5B, Rhodamine B (RhB), Methyl Orange (MO), Methyl Red (MR), Methylene Blue (MB), and Congo Red (CR) by Ag / WS2 / BiOI were 88.24%, 2.45%, 11.57%, 91.62%, 22.83%, and 81.04%, respectively. These differences in removal efficiency may be due to the different chemical structures of various pollutants, leading to differences in adsorption and degradation capabilities on the surface of the photocatalytic material, thus affecting the photocatalytic efficiency.

[0061] 7. Free radical capture experiment: Figure 7 This is an experimental spectrum of free radical capture of the photocatalytic material prepared in Example 1.

[0062] Capture experiments are used to study the main active substances involved in photocatalysis, which is of great significance for exploring the mechanism of photocatalytic reactions. Disodium ethylenediaminetetraacetate (EDTA-2Na), p-benzoquinone (BQ), and isopropanol (IPA) are used as capture agents for holes (h) and other reactive substances, respectively. + ), superoxide radicals ( Capture of reactive substances such as hydroxyl radicals (•OH) and hydroxyl radicals (•OH). Figure 7 As shown, after the addition of EDTA-2Na, the degradation rate of Lanazon Red 5B decreased to 22.58%, indicating that EDTA-2Na effectively captured the h generated during the photocatalytic process. + BQ inhibits the degradation of Lanazol Red 5B. After the addition of BQ, the degradation rate of Lanazol Red 5B decreased to 25.13%, indicating that BQ effectively captured [the degradation]. This hinders the degradation of Lanazol Red 5B. When IPA is used as a scavenger, the degradation rate of Lanazol Red 5B is 83.96%, slightly lower than the degradation rate under normal conditions. The results indicate that h + and It is the main active species in this photocatalytic reaction, while •OH plays an auxiliary role in degradation.

[0063] In summary, the Ag / WS2 / BiOI photocatalytic material prepared in this invention exhibits the best removal effect on 80 mg / L Lanazol Red 5B after 20 minutes of simulated sunlight irradiation, with a removal rate of 88.24%, which is 1.81, 9.40, and 1.39 times that of pure BiOI, WS2, and WS2 / BiOI photocatalytic materials, respectively. The photocatalytic degradation efficiency of Ag / WS2 / BiOI is significantly improved.

[0064] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. Application of Ag / WS2 / BiOI nano-photocatalytic material containing oxygen vacancies in photocatalytic degradation of Lanasol Red 5B, characterized in that, The preparation method of the photocatalytic material comprises the following steps: S1, a stirring-precipitation method is used to prepare a binary oxygen vacancy WS2 / BiOI heterojunction: WS2 powder is dissolved in an ethanol solution and ultrasonic treatment is performed to obtain uniformly dispersed WS2 nanosheets; then, a certain amount of WS2 nanosheets is added to a solution of ethylene glycol and deionized water to obtain solution A, Bi(NO3)3·5H2O is added to solution A, stirring is continued, then thiourea is added, stirring is continued, KI is added, then glacial acetic acid solution is added, stirring is continued and reaction is performed, and after the reaction is completed, WS2 / BiOI heterojunction precipitate is obtained, the obtained heterojunction precipitate is washed, dried and ground into powder for use; S2, an Ag / WS2 / BiOI nano photocatalytic material is prepared by using a light reduction method: The WS2 / BiOI heterojunction powder obtained in step S1 is added to deionized water and ultrasonic treatment is performed to obtain solution B; an AgNO3 solution prepared is added dropwise to solution B and stirring is performed to obtain solution C, and solution C is placed under a xenon lamp for light irradiation, and then solution C is centrifuged and dried to obtain the Ag / WS2 / BiOI photocatalytic material; In step S1, the steps for preparing solution A are as follows: 0.2-0.3 g of WS2 powder is dissolved in 80-120 ml of 70% ethanol solution, ultrasonic treatment is performed for 10 hours, and after drying, WS2 nanosheets are obtained, then 0.02-0.04 g of the prepared WS2 nanosheets is weighed and added to 80-120 ml of a solution of 50% ethylene glycol and 50% deionized water to obtain solution A; In step S1, 0.4-0.5 g of Bi(NO3)3·5H2O is added to solution A and stirring is performed for 10 minutes, then 10-30 ml of thiourea solution with a concentration of 1 mol / L is added, stirring is continued for 10-15 minutes, then 0.1-0.2 g of KI is added, and then 80-120 ml of glacial acetic acid solution with a concentration of 99% is added, and stirring is continued for 1 hour. 2.The application of the Ag / WS 2 / BiOI nanophotocatalytic material containing oxygen vacancies in photocatalytic degradation of rhodamine 5B according to claim 1, characterized in that, In step S1, the precipitate after the reaction is completed is washed with deionized water and anhydrous ethanol three times each, and then is placed in a drying oven for drying at 80-100°C. 3.The application of the Ag / WS 2 / BiOI nanophotocatalytic material containing oxygen vacancies in photocatalytic degradation of rhodamine 5B according to claim 1, characterized in that, In step S2, the preparation steps of solution B are as follows: 0.4-0.6 g of WS2 / BiOI heterojunction powder is added to 30 ml of deionized water to obtain a suspension and ultrasonic treatment is continued for 1 hour to form a uniform suspension. 4.The application of the Ag / WS 2 / BiOI nanophotocatalytic material containing oxygen vacancies in photocatalytic degradation of rhodamine 5B according to claim 1, characterized in that, In step S2, the prepared AgNO3 solution has a concentration of 3.1-3.5 mg / ml and a preparation amount of 4-6 ml.

5. The application of the Ag / WS2 / BiOI nano-photocatalytic material containing oxygen vacancies in photocatalytic degradation of rhodamine 5B according to claim 1, characterized in that, In step S2, the treatment steps of solution C are as follows: after solution C is stirred on a magnetic stirrer for 2-3 h, the fully adsorbed solution C is placed under a 350 W xenon lamp for light irradiation for 2-3 h.

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