Nanometer photocatalyst, preparation method and application thereof

Abstract

The application relates to a nano photocatalyst and a preparation method and application thereof. The application relates to an oxygen vacancy-rich Ag2MoO4 / BiOCl nano photocatalyst, which is formed by Ag2MoO4 and BiOCl to form an interlaced Z-type heterojunction, wherein the mass fraction of Ag2MoO4 is 1-15%. The preparation method of the photocatalyst comprises the following steps: S1, adding 0.1503g of BiOCl into 50ml of deionized water and carrying out ultrasonic treatment to realize dispersion; S2, adding 0.0068-0.0363g of AgNO3 solution into the suspension obtained in step S1 drop by drop, continuously stirring to obtain a suspension A; S3, dissolving 0.0014-0.0204g of Na2MoO4.2H2O in 20ml of water to obtain a solution B, continuously stirring, adding the solution A drop by drop, stirring for 0.5-1 hours and standing; and S4, cleaning the obtained precipitate by using deionized water and anhydrous ethanol for several times, and drying to obtain an Ag2MoO4 / BiOCl heterojunction nano material. The application solves the problems of low visible light utilization rate, low photoelectron hole separation efficiency and easy recombination of a photocatalytic material, effectively improves the photocatalytic activity of BiOCl, and has the advantages of simple synthesis method, greenness, safety, low cost and the like.

Description

Technical Field

[0001] This invention relates to a nanophotocatalyst, and more particularly to a method for preparing an oxygen-vacancy-rich Ag2MoO4 / BiOCl nanophotocatalyst. Background Technology

[0002] With the rapid development of industrialization, water pollution has become a major concern. In the medical and health field, water pollution is inevitable, posing a threat to human health and ecological balance. To address this problem, researchers have continuously explored various treatment methods, such as physical adsorption, chemical removal, and biodegradation, but with limited success. In recent years, photocatalysis technology, known for its simple and rapid operation, high efficiency, energy saving, and environmental friendliness, has shown potential for development and application in various fields such as environmental pollution control and clean green energy utilization. However, traditional semiconductor photocatalysts still face many problems in application, such as low utilization of sunlight and easy recombination of photogenerated electrons and holes, which limits their practical application.

[0003] Bismuth oxychloride (BiOCl) is a tetragonal crystalline powder with a silvery-white, pearly luster and a relative molecular mass of 260.43. It is insoluble in water but soluble in hydrochloric acid and nitric acid. Upon heating to 700°C, it decomposes and releases bismuth trichloride. BiOCl is non-toxic, has low oil absorption, strong skin adhesion, and excellent pearlescent effect, making it widely used as a raw material in cosmetic synthesis, such as in face powder, nail polish, and eyeshadow. BiOCl pearlescent paste can be used to manufacture paint pigments and other products. BiOCl is also used in the manufacture of artificial pearls and as a cathode for dry cell batteries.

[0004] Studies have found that bismuth oxychloride, as a bismuth-based semiconductor material with a unique structure, suitable band gap, and good photocatalytic performance, is widely used in the field of photocatalysis. BiOCl belongs to the V-VI-VIII group of ternary semiconductor materials and has a tetragonal fluoride chlorite (PbFCl) structure. BiOCl crystals have a layered structure, consisting of [Bi₂O₂]. 2+ Layers are interspersed in sequence, consisting of double-layer Cl –Ions are linked together by van der Waals forces. The internal electrostatic field generated by the layered structure facilitates the accelerated separation of charge carriers, thus improving photocatalytic activity. Oxygen vacancy (OV) technology can optimize the band gap width of semiconductors and promote the effective separation of photogenerated electrons and holes, and has been widely studied and adopted. By controlling the synthesis process of BiOCl, BiOCl rich in oxygen vacancies can be prepared. OVs have a significant impact on the electronic structure and physical properties of semiconductors, and can reduce the band gap width of BiOCl and improve the visible light response. Oxygen vacancies on the BiOCl (001) surface can also induce the generation of free hydroxyl radicals, while oxygen vacancies on the BiOCl (010) surface selectively generate surface hydroxyl radicals. Hydroxyl radicals in different forms exhibit different organic pollutant removal characteristics, effectively improving the photocatalytic activity of BiOCl.

[0005] In recent years, silver-based metal oxides such as Ag₂CrO₄, Ag₂MoO₄, Ag₂WO₄, and Ag₃PO₄ have been studied. Among them, Ag₂MoO₄ has attracted much attention due to its good performance in photocatalysis and antibacterial activity. Silver molybdate (Ag₂MoO₄) is a white solid with a tetrahedral ionic structure, stable properties, and insoluble in any solvent. As a commonly used photocatalyst, Ag₂MoO₄ exhibits good visible light response and is widely used in environmental remediation. Silver molybdate has good chemical stability during photocatalysis and is not easily decomposed. The crystal form and morphology of Ag₂MoO₄ can be controlled through synthesis methods to optimize its photocatalytic performance. Although silver molybdate has a good response to visible light, the high recombination rate of photogenerated electron-hole pairs still limits its photocatalytic performance. Silver molybdate typically has poor electrical conductivity, which may affect charge transport efficiency. Through defect engineering, heterojunction construction, and doping modification strategies, the photocatalytic performance of the material can be further improved, expanding its application in environmental remediation.

[0006] Based on the above, if we can utilize the unique characteristics of BiOCl and Ag2MoO4 to develop Ag2MoO4 / BiOCl nanocatalysts rich in oxygen vacancies, we can certainly improve the photocatalytic performance of the materials. Currently, no research in this area has been reported. Summary of the Invention

[0007] To address the problems of low visible light utilization, low efficiency of photogenerated electron-hole separation, and easy recombination in photocatalytic materials, this invention proposes an oxygen-vacancy-rich Ag2MoO4 / BiOCl nanocatalyst and its preparation method.

[0008] To achieve the above objectives, the specific solution adopted by the present invention is as follows:

[0009] On one hand, the present invention provides an Ag2MoO4 / BiOCl nanophotocatalyst, wherein the Ag2MoO4 / BiOCl nanophotocatalyst is an interlaced Z-shaped heterojunction formed by Ag2MoO4 and BiOCl, wherein the mass fraction of Ag2MoO4 is 1-15%.

[0010] Furthermore, Ag2MoO4 has a cubic structure, and the cubic Ag2MoO4 is dispersed in the plate-like BiOCl.

[0011] Furthermore, the mass fraction of Ag2MoO4 is 5%.

[0012] On the other hand, the present invention provides an Ag2MoO4 / BiOCl nanocatalyst and its preparation method, which mainly includes the following steps:

[0013] S1. BiOCl nanosheets were prepared by low-temperature water bath method. The BiOCl nanosheets were ultrasonically dispersed in deionized water to obtain a suspension.

[0014] S2. Add AgNO3 to the suspension and ultrasonically disperse it evenly. This allows the AgNO3 particles to dissolve better, ensuring the Ag... + It can be effectively adsorbed on the BiOCl surface to form Ag. + The solution was prepared by adding excess Na₂MoO₄·2H₂O to BiOCl, and then stirring thoroughly at room temperature to ensure that the dissolved Ag was completely dissolved. + The reaction proceeds completely, and Ag2MoO4 precipitates at room temperature. Ag2MoO4 is deposited on the surface of BiOCl, forming an Ag2MoO4 / BiOCl heterojunction. Then, the mixture is centrifuged, and the supernatant is discarded to obtain the precipitate.

[0015] S3. The precipitate was washed with deionized water and anhydrous ethanol respectively, and then placed in a drying oven for vacuum drying to obtain Ag2MoO4 / BiOCl nano-photocatalyst, which was then ground into powder for later use.

[0016] Furthermore, in step S1, the method for preparing BiOCl nanosheets by low-temperature water bath is as follows:

[0017] 1) First, dissolve 3 mmol of Bi(NO3)3·5H2O in 45 mL of deionized water to form solution A;

[0018] 2) Disperse 1.2g of polyvinylpyrrolidone (PVP) in solution A;

[0019] 3) Then, take 6 mmol of NaCl and disperse it in 22.5 mL of deionized water to prepare solution B, and make the solution evenly dispersed;

[0020] 4) After the solution is evenly dispersed, add solution B dropwise to solution A, stir magnetically for 2 hours in a 90℃ water bath, and let stand.

[0021] 5) Wash the precipitate obtained by settling several times with deionized water and anhydrous ethanol, then vacuum dry it. After drying, grind it for later use. The drying temperature is 60-90°C and the time is 12-24 hours.

[0022] The Ag2MoO4 / BiOCl nanocatalysts described above can be used for the photocatalytic degradation of organic pollutants.

[0023] Beneficial effects of the invention:

[0024] 1. This invention synthesizes oxygen-vacancy BiOCl nanosheets via a water bath method and prepares Ag₂MoO₄ / BiOCl heterojunctions using an in-situ precipitation method. These heterojunctions are constructed from BiOCl nanosheets and Ag₂MoO₄ crystals. The resulting Ag₂MoO₄ / BiOCl heterojunctions exhibit highly efficient photocatalytic activity against various organic pollutants under visible light (LR5B (100% removal rate), SAT (100% removal rate), CIP (80.44% removal rate), TC (60.24% removal rate), RhB (51.74% removal rate)). The loading of Ag₂MoO₄ significantly affects the photocatalytic properties of the composite material. A loading of 5% Ag₂MoO₄ exhibits the best photocatalytic effect, achieving a CIP degradation rate of 80.44% after 180 minutes, which is 3.27 times and 1.90 times that of pure Ag₂MoO₄ and BiOCl, respectively.

[0025] 2. The preparation method of Ag₂MoO₄ / BiOCl nanocatalyst of this invention produces BiOCl containing oxygen vacancies. The formation of oxygen vacancies is beneficial to improving the photocatalytic performance of the material. For the Ag₂MoO₄ / BiOCl heterojunction, the band gap of BiOCl is approximately 3.2 eV, and the band gap of Ag₂MoO₄ is approximately 2.9 eV, which can form an interleaved Z-shaped heterojunction, which is conducive to the rapid separation of photogenerated electron-hole pairs and improves the photocatalytic performance of the material. Oxygen vacancy (OV) technology can optimize the band gap of semiconductors and promote the effective separation of photogenerated electrons and holes, and has been widely studied and used. By controlling the BiOCl synthesis process, BiOCl rich in oxygen vacancies can be prepared. OVs have a significant impact on the electronic structure and physical properties of semiconductors, and can reduce the band gap of BiOCl and improve the visible light response. Oxygen vacancies on the BiOCl(001) surface can induce the generation of free hydroxyl radicals, while oxygen vacancies on the BiOCl(010) surface selectively generate surface hydroxyl radicals. The different forms of hydroxyl radicals exhibit different organic pollutant removal characteristics, effectively enhancing the photocatalytic activity of BiOCl.

[0026] 3. The preparation method of the Ag2MoO4 / BiOCl nanocatalyst of this invention is simple and does not require large-scale synthesis equipment; the synthesis conditions are mild, at 90°C under normal pressure; and the reagents required for synthesis are all conventional reagents with low toxicity and low cost. In summary, this scheme is a simple, green, safe, and low-cost synthesis process for preparing efficient and stable photocatalysts. Attached Figure Description

[0027] Figure 1 The XRD patterns of the photocatalytic materials in each embodiment and comparative example are shown below.

[0028] Figure 2 SEM images of the photocatalytic materials prepared in Comparative Examples 1, 2 and Example 3;

[0029] Figure 3 The photocatalytic degradation spectra of ciprofloxacin by the photocatalytic materials in each embodiment and comparative example are shown.

[0030] Figure 4 The reaction rate constants for the degradation of ciprofloxacin under control conditions in each embodiment and comparative example are plotted.

[0031] Figure 5 The graph shows the degradation effect of the photocatalytic material prepared in Example 3 on ciprofloxacin in the presence of different ions.

[0032] Figure 6 This is a spectrum showing the degradation of ciprofloxacin by the photocatalytic material prepared in Example 3 when multiple pollutants coexist.

[0033] Figure 7 The image shows the free radical capture experiment spectrum of the photocatalytic material prepared in Example 3. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the present invention and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0035] This invention provides an oxygen-vacancy-rich Ag₂MoO₄ / BiOCl nanocatalyst, wherein the Ag₂MoO₄ / BiOCl nanocatalyst is a staggered Z-shaped heterojunction formed by Ag₂MoO₄ and BiOCl, wherein the Ag₂MoO₄ has a cubic structure, and the cubic AgBiO₃ is dispersed in the sheet-like BiOCl. The mass fraction of Ag₂MoO₄ is 1–15%.

[0036] Example 1

[0037] This embodiment provides a method for preparing Ag2MoO4 / BiOCl nanocatalysts, wherein the mass fraction of Ag2MoO4 in the photocatalyst is 1% (denoted as AB-1), and mainly includes the following steps:

[0038] S1. First, dissolve 3 mmol of Bi(NO3)3·5H2O in 45 mL of deionized water to form solution A;

[0039] S2. Disperse 1.2g of polyvinylpyrrolidone (PVP) in solution A;

[0040] S3. Disperse 6 mmol of NaCl in 22.5 mL of deionized water until the solution is evenly dispersed to form solution B;

[0041] S4. Add solution B dropwise to solution A, then stir magnetically under a 90°C water bath until homogeneous. After standing, discard the supernatant to obtain a precipitate.

[0042] S5. Wash the precipitate with deionized water, and then dry it in a vacuum drying oven to obtain BiOCl nanosheets. After drying and grinding, they are ready for use.

[0043] S6. Place 0.1503g of BiOCl nanopowder in 50ml of deionized water, and sonicate it in an ultrasonic machine for 10min to disperse the BiOCl nanopowder into the deionized water to obtain a suspension.

[0044] S7. Add 0.0014g AgNO3 to the suspension and continue to disperse by ultrasonication for 30min. Then add 0.0024g Na2MoO4·2H2O and stir at 25℃ for 1h. Then centrifuge and discard the supernatant to obtain the precipitate.

[0045] S8. The precipitate was washed with deionized water and anhydrous ethanol respectively, and then placed in a drying oven and vacuum dried at 80°C to obtain Ag2MoO4 / BiOCl nanophotocatalyst, which was then ground into powder for later use.

[0046] Example 2

[0047] The difference between this embodiment and Example 1 is that: (1) the mass fraction of Ag2MoO4 in the Ag2MoO4 / BiOCl nanophotocatalyst is 3% (denoted as AB-3); (2) in step S7, the amount of AgNO3 added is 0.0041g and the amount of Na2MoO4·2H2O added is 0.0073g.

[0048] Example 3

[0049] The difference between this embodiment and Example 1 is that: (1) the mass fraction of Ag2MoO4 in the Ag2MoO4 / BiOCl nanophotocatalyst is 5% (denoted as AB-5); (2) in step S7, the amount of AgNO3 added is 0.0068g and the amount of Na2MoO4·2H2O added is 0.0121g.

[0050] Example 4

[0051] The difference between this embodiment and Example 1 is that: (1) the mass fraction of Ag2MoO4 in the Ag2MoO4 / BiOCl nanophotocatalyst is 10% (denoted as AB-10); (2) in step S7, the amount of AgNO3 added is 0.0136g and the amount of Na2MoO4·2H2O added is 0.0242g.

[0052] Example 5

[0053] The difference between this embodiment and Example 1 is that: (1) the mass fraction of Ag2MoO4 in the Ag2MoO4 / BiOCl nanophotocatalyst is 15% (denoted as AB-15); (2) in step S7, the amount of AgNO3 added is 0.0204g and the amount of Na2MoO4·2H2O added is 0.0363g.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that it only includes steps S1 to S5, which yields a BiOCl photocatalyst.

[0056] 1. Phase structure: The phase structure was analyzed using X-ray diffraction. Detailed test results are available in [link to relevant documentation]. Figure 1 .

[0057] The composition and structure of BiOCl, Ag2MoO4, and a series of Ag2MoO4 / BiOCl composites were investigated by XRD testing. Figure 1As shown, the pure BiOCl sample exhibits distinct diffraction peaks at 25.8°, 32.5°, 33.4°, 40.8°, 46.6°, 49.7°, 54.1°, and 58.6°, corresponding to the (101), (110), (102), (112), (200), (113), (211), and (212) crystal planes of BiOCl, respectively, indicating a tetragonal phase structure (JCPDS No. 06-0249). In contrast, Ag₂MoO₄ shows characteristic diffraction peaks at 27.1°, 31.8°, 33.3°, 38.6°, 50.1°, and 55.8°, consistent with the diffraction peaks of Ag₂MoO₄ (JCPDS No. 08-0473). Overall, the Ag₂MoO₄ / BiOCl composite material exhibits diffraction peaks consistent with those of the tetragonal BiOCl phase. When the Ag₂MoO₄ loading exceeds 5% (AB-5, AB-10, AB-15), a diffraction peak of Ag₂MoO₄ appears at 33.3°, corresponding to the (222) plane of Ag₂MoO₄. This diffraction peak gradually intensifies with increasing Ag₂MoO₄ content, indicating the formation of an Ag₂MoO₄ / BiOCl heterojunction. The absence of other impurity peaks indicates high phase purity of the sample.

[0058] The above phase structure analysis results show that the present invention successfully synthesized Ag2MoO4 / BiOCl heterojunction photocatalytic material.

[0059] 2. Morphology and Structure: The surface morphology of the catalyst was observed using field emission scanning electron microscopy. Detailed test results are available in [link to relevant documentation]. Figure 2 .

[0060] Figure 2 SEM images of BiOCl, Ag2MoO4, and Ag2MoO4 / BiOCl heterojunctions. From... Figure 2 As can be seen in (a), pure BiOCl exhibits a smooth nanosheet structure. Figure 2 (b) Pure Ag₂MoO₄ exhibits a cubic crystal structure with a diameter of approximately 1-2 μm. Ag₂MoO₄ / BiOCl heterojunction ( Figure 2 (c) shows that the cubic crystal Ag2MoO4 is surrounded by plate-like BiOCl, confirming that Ag2MoO4 and BiOCl have good interfacial contact, which is conducive to the interfacial reaction.

[0061] 3. Figure 3 The photocatalytic degradation spectra of ciprofloxacin by the photocatalytic materials of each embodiment and comparative example are shown.

[0062] 40 mg of photocatalysts (BiOCl, Ag₂MoO₄, AB-1, AB-3, AB-5, AB-10, AB-15) were dispersed in 40 mL of a 10 mg / L ciprofloxacin solution. Adsorption was carried out in the dark for 30 minutes to reach adsorption-desorption equilibrium. Irradiation was performed for 180 minutes using a 350 W xenon lamp (with a 420 nm cutoff filter), with samples taken every 30 minutes. The samples were centrifuged, and the absorbance was measured using a UV-Vis spectrophotometer to analyze the photocatalytic degradation effect. Detailed test results are available in [link to test results]. Figure 3 .

[0063] The photocatalytic performance of the synthesized sample was tested under visible light with CIP as the target pollutant. Figure 3 To evaluate the degradation performance of CIP by different catalysts under visible light, pure Ag₂MoO₄ and BiOCl photocatalysts showed degradation rates of only 24.60% and 42.25% respectively within 180 minutes. Under the same conditions, the 5% Ag₂MoO₄ / BiOCl heterojunction exhibited the strongest photocatalytic activity, achieving a CIP degradation rate of 80.44%. Figure 3 As shown, the degradation efficiency of the Ag2MoO4 / BiOCl heterojunction first increases and then decreases with increasing Ag2MoO4 content, indicating that Ag2MoO4 plays an important role in the photocatalytic degradation process. This is mainly because Ag2MoO4 is beneficial for enhancing light absorption and promoting the separation of photogenerated charge carriers. However, excessive Ag2MoO4 may form electron-hole recombination centers, ultimately reducing photocatalytic activity. The photocatalytic activity of the mechanically mixed BiOCl and Ag2MoO4 nanosheets is lower than that of the Ag2MoO4 / BiOCl heterojunction, indicating that a good interfacial reaction is formed between Ag2MoO4 and BiOCl.

[0064] 4. Figure 4 The reaction rate constants for the degradation of ciprofloxacin by the photocatalytic materials in each embodiment and comparative example are plotted. Figure 4 In the AB-5 heterojunction, the kinetic rate constant (k) is approximately 0.01192 min. -1 It is 2.76, 5.67, 1.71, 1.01, 1.33 and 1.13 times that of pure BiOCl, Ag2MoO4, AB-1, AB-3, AB-10 and AB-15, respectively.

[0065] 5. Figure 5 The image shows the degradation effect of the photocatalytic material prepared in Example 3 on ciprofloxacin in the presence of different ions. To simulate a real aquatic environment, 1 mmol of chloride ions (Cl) was added to the ciprofloxacin solution in this experiment. - ), sulfate ions (SO4) 2- ), phosphate ions (PO4) 3-) and dihydrogen phosphate ions (H2PO4) - To investigate the effect of ions on photocatalytic activity. For example... Figure 5 As shown, the degradation of CIP was inhibited to varying degrees after the addition of ions, with PO4 being the most significant inhibitory effect. 3- The inhibitory effect was most significant, with the removal rate decreasing to 7.81%, possibly due to PO4. 3- It participates in the photocatalytic reaction process, competing with the generated electrons and holes, thereby reducing the number of effective charge carriers involved in the degradation of ciprofloxacin. H2PO4 - After its addition, the removal rate of CIP decreased to 40.48%, indicating that H2PO4 removal was reduced. - It has some impact on the degradation of CIP, possibly due to H2PO4. - It undergoes ionization and hydrolysis in aqueous solution, with the ionization reaction being more pronounced than the hydrolysis reaction, ultimately releasing H₂. + This lowers the pH of the solution, leading to a decrease in photocatalytic activity. SO4 2- and Cl - The inhibitory effect was relatively weak, with CIP removal rates of 47.22% and 58.80%, respectively. SO4 2- The main mechanism is to reduce the catalyst activity by capturing hydroxyl radicals and photogenerated holes. - The capture of ·OH forms corresponding inorganic anionic free radicals, thereby reducing the activity of the catalyst.

[0066] 6. Figure 6 This is a spectrum showing the degradation of ciprofloxacin by the photocatalytic material prepared in Example 3 under the coexistence of multiple pollutants. In studying the photocatalytic activity of the Ag₂MoO₄ / BiOCl heterojunction, the possibility of multiple pollutants coexisting in real aquatic environments was considered. Experimental results are as follows... Figure 6 As shown, when LR5B and RhB coexisted with CIP, the degradation of CIP was significantly inhibited, with CIP removal rates of 52.80% and 34.54%, respectively. This may be due to the competition between organic pollutants and the bioactive species.

[0067] 7. Free radical capture experiment: Figure 7 The image shows the free radical capture experiment spectrum of the photocatalytic material prepared in Example 3.

[0068] To investigate the photocatalytic mechanism of Ag2MoO4 / BiOCl heterojunctions, three different trapping agents were introduced, namely those commonly used to trap holes (h + Disodium ethylenediaminetetraacetate (EDTA-2Na) is often used to capture superoxide radicals (·O2). -The study investigated the active substances that play a major role in the photocatalysis of Ag₂MoO₄ / BiOCl heterojunctions, using p-benzoquinone (BQ) and isopropanol (IPA), which is commonly used to capture hydroxyl radicals (·OH). Figure 7 As shown, the degradation rate of CIP was extremely low, only 10%, with the addition of EDTA-2Na. This indicates that EDTA-2Na may have effectively captured the holes generated during photocatalysis, thus hindering further degradation of CIP. When BQ was added, the degradation rate of CIP was very low at 30.16%, significantly lower than the degradation rate under normal conditions. When IPA was used as a capture agent, the degradation rate of CIP was 42.13%, lower than the normal 80.44%. The results indicate that holes are the main active substance in this photocatalytic reaction. - Both ·OH and ·OH play a role in assisting degradation.

[0069] In summary, the Ag2MoO4 / BiOCl photocatalytic material synthesized in this invention achieves a degradation efficiency of 80.44% for ciprofloxacin within 180 minutes under visible light irradiation. This is 3.27 times and 1.90 times that of pure Ag2MoO4 and BiOCl photocatalysts, respectively. The photocatalytic degradation efficiency of Ag2MoO4 / BiOCl is significantly improved, with the Ag2MoO4 / BiOCl heterojunction with a doping amount of 5% exhibiting the best photocatalytic degradation efficiency.

[0070] The above description is merely a preferred embodiment of the present invention and does not constitute a limitation thereof. Those skilled in the art, guided by existing technology, can make other modifications to the implementation of the present invention without creative effort. Any modifications made within the spirit and principles of the present invention, or simple substitutions or equivalent replacements using conventional techniques in the art, should be included within the scope of protection of the present invention.

Claims

1. A photocatalyst for Ag₂MoO₄ / BiOCl nanoparticles rich in oxygen vacancies, characterized in that: The Ag2MoO4 / BiOCl nanocatalyst is a staggered Z-shaped heterojunction formed by Ag2MoO4 and BiOCl, wherein the Ag2MoO4 has a cubic structure and is dispersed in sheet-like BiOCl, with a mass fraction of Ag2MoO4 of 1-15%; the preparation method of the nanocatalyst includes the following steps: S1. BiOCl nanosheets were prepared by low-temperature water bath method. The BiOCl nanosheets were ultrasonically dispersed in deionized water to obtain a suspension. S2, AgNO3 is added to the suspension, ultrasonic dispersion, uniform dissolution to ensure Ag + can be effectively adsorbed on the surface of BiOCl, forming Ag + -BiOCl solution, then an excess of Na2MoO4·2H2O is added thereto, and stirred uniformly at room temperature to ensure that the dissolved Ag + react completely, Ag2MoO4 is deposited on the surface of BiOCl, forming Ag2MoO4 / BiOCl heterojunction, centrifugation, pour the supernatant to obtain the precipitate; S3. The precipitate was washed with deionized water and anhydrous ethanol respectively, and then placed in a drying oven for vacuum drying to obtain Ag2MoO4 / BiOCl nano-photocatalyst, which was then ground into powder for later use.

2. The Ag₂MoO₄ / BiOCl nanocatalyst according to claim 1, characterized in that: The mass fraction of Ag2MoO4 is 5%.

3. A method for preparing the oxygen-vacancy-rich Ag₂MoO₄ / BiOCl nanocatalyst as described in claim 1, characterized in that, The steps include the following: S1. BiOCl nanosheets were prepared by low-temperature water bath method. The BiOCl nanosheets were ultrasonically dispersed in deionized water to obtain a suspension. S2. Add AgNO3 to the suspension, disperse by ultrasonication, and dissolve evenly to ensure Ag... + It can be effectively adsorbed on the BiOCl surface to form Ag. + The solution was prepared by adding excess Na₂MoO₄·2H₂O to BiOCl, and then stirring thoroughly at room temperature to ensure that the dissolved Ag was completely dissolved. + After complete reaction, Ag2MoO4 is deposited on the BiOCl surface to form Ag2MoO4 / BiOCl heterojunction. After centrifugation, the supernatant is discarded to obtain the precipitate. S3. The precipitate was washed with deionized water and anhydrous ethanol respectively, and then placed in a drying oven for vacuum drying to obtain Ag2MoO4 / BiOCl nano-photocatalyst, which was then ground into powder for later use.

4. The preparation method of Ag2MoO4 / BiOCl nanocatalyst according to claim 3, characterized in that: In step S1, the process of preparing BiOCl nanosheets by low-temperature water bath method includes: 1) First, dissolve 3 mmol of Bi(NO3)3·5H2O in 45 mL of deionized water to form solution A; 2) Then, take 1.2g of polyvinylpyrrolidone and disperse it in solution A; 3) Then, take 6 mmol of NaCl and disperse it in 22.5 mL of deionized water to prepare solution B, and make the solution evenly dispersed; 4) After the solution is evenly dispersed, add solution B dropwise to solution A, stir magnetically for 2 hours in a 90℃ water bath, and let stand. 5) Wash the precipitate obtained by standing with deionized water and anhydrous ethanol, vacuum dry, and grind it for later use.

5. The preparation method of Ag2MoO4 / BiOCl nanocatalyst according to claim 3, characterized in that: In step S1, 0.1503 g of BiOCl is added to 50 mL of deionized water and ultrasonically treated to achieve dispersion.

6. The method for preparing Ag₂MoO₄ / BiOCl nanocatalyst according to claim 3, 4, or 5, characterized in that: In step S2, 0.0068 g to 0.0363 g of AgNO3 solution is added dropwise to the suspension obtained in step S1, and the mixture is stirred continuously for 30 to 40 minutes to obtain suspension A; then 0.0014 g to 0.0204 g of Na2MoO4·2H2O is dissolved in 20 mL of water to obtain solution B. Solution B is stirred continuously, and solution A is added dropwise while stirring for another 0.5 to 1 hour; then the mixture is allowed to stand to obtain the precipitate.

7. The preparation method of Ag2MoO4 / BiOCl nanocatalyst according to claim 6, characterized in that: In step S3, the precipitate obtained by standing is washed several times with deionized water and anhydrous ethanol, then vacuum dried at a temperature of 60-90℃ for 12-24 hours.

8. The application of the Ag2MoO4 / BiOCl nanophotocatalyst according to claim 1 or the Ag2MoO4 / BiOCl nanophotocatalyst prepared by the preparation method according to claim 3 in the photocatalytic degradation of organic pollutants.

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