A photocatalytic material based on Bi2O2S, its preparation method and application

Abstract

This invention proposes a photocatalytic material based on Bi2O2S, its preparation method, and its application. The Bi2O2S-based photocatalytic material comprises Bi2O2S, oxygen vacancies introduced onto the Bi2O2S, and an S-type heterojunction constructed on the Bi2O2S. The Bi2O2S-based photocatalytic material is O... V -Bi2O2S / Bi4O5I2 composite photocatalytic material; the O V The preparation method of the -Bi2O2S / Bi4O5I2 composite photocatalyst material includes: Step 1) preparing O V -Bi2O2S catalyst; Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalytic material; the O V The Bi2O2S / Bi4O5I2 composite photocatalytic material is suitable for hydrogen peroxide synthesis; this invention is a novel composite photocatalytic material with a novel structure and excellent performance.

Description

Technical Field

[0001] This invention relates to a photocatalytic material based on Bi2O2S, its preparation method and application, belonging to the field of photocatalytic material technology. Background Technology

[0002] Hydrogen peroxide is considered an important industrial chemical raw material due to its oxidation / reduction properties, eco-friendliness, and high energy release. Its applications cover multiple fields such as pulp bleaching, environmental remediation, liquid propellants, and disinfection. In recent years, hydrogen peroxide has also shown great potential to replace hydrogen power generation in single-chamber batteries due to its liquid form, storability, and high safety.

[0003] Currently, hydrogen peroxide is mainly produced through the anthraquinone process, but the traditional anthraquinone process has drawbacks such as high energy consumption and the emission of large amounts of toxic byproducts. Therefore, the search for a low-energy-consumption and environmentally friendly method for producing hydrogen peroxide has attracted widespread attention. Since semiconductor photocatalysis technology only requires H2O, O2, and light energy, and also has the advantages of being pollution-free and having abundant reserves, it is considered one of the most promising H2O2 synthesis technologies. However, the problem of low yield of hydrogen peroxide produced by semiconductor photocatalysis technology still needs to be solved.

[0004] In semiconductor photocatalytic materials, low-dimensional bismuth oxysulfide (Bi2O2S) has attracted widespread attention in the fields of electronics and optoelectronics due to its excellent stability, high carrier mobility and unique structure. Although there is an interesting interaction between the internal electrostatic field and non-equilibrium carrier properties, Bi2O2S has encountered difficulties in photocatalytic applications due to its rapid carrier recombination.

[0005] Introducing oxygen vacancies (O V The formation of heterojunctions can effectively modulate the band structure and light absorption capacity of Bi2O2S, thereby improving the adsorption and activation of O2 molecules; for example, Chinese invention patent application number 202311229674.4 discloses a Bi2O2S / Bi 12 TiO 20 Preparation methods and applications of composite photocatalytic materials, but Bi2O2S / Bi 12 TiO 20 Heterojunctions are affected by strain fields and structural defects caused by lattice mismatch, resulting in poor interface quality. Chinese invention patent application No. 202010967455.6 discloses a Co-doped Bi2O2S catalyst, its preparation method and application. However, Co-doped Bi2O2S catalysts have disadvantages such as narrow band structure, low light absorption capacity and rapid carrier recombination, and still have problems such as insufficient photocatalytic activity. Summary of the Invention

[0006] This invention proposes a photocatalytic material based on Bi2O2S, its preparation method and application, with the aim of improving the photocatalytic activity of Bi2O2S catalysts.

[0007] The technical solution of the present invention: a photocatalytic material based on Bi2O2S, the structure of which includes Bi2O2S, oxygen vacancies introduced on Bi2O2S, and an S-shaped heterojunction constructed on Bi2O2S.

[0008] The photocatalytic material based on Bi2O2S is O V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

[0009] Furthermore, the O V The preparation methods of Bi2O2S / Bi4O5I2 composite photocatalytic materials include:

[0010] Step 1) Preparation of O V -Bi2O2S catalyst;

[0011] Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

[0012] Further, in step 1), O is prepared. V -Bi2O2S, specifically including:

[0013] Step 1-1) Dissolve thiourea and bismuth nitrate in distilled water and stir to form a mixed solution of thiourea and bismuth nitrate. Then add lithium hydroxide to the mixed solution of thiourea and bismuth nitrate and stir to form a first mixture.

[0014] Step 1-2) The first mixture is transferred to a heating container for heating. After heating, the mixture is washed and dried to obtain Bi2O2S.

[0015] Steps 1-3) Calcine Bi₂O₂S under a nitrogen atmosphere to obtain O V -Bi2O2S.

[0016] Further, in step 2), O is prepared. V -Bi2O2S / Bi4O5I2 composite photocatalytic materials, specifically including:

[0017] Step 2-1) Add bismuth nitrate to the mannitol solution and stir to form a bismuth nitrate solution;

[0018] Step 2-2) Take the O prepared in step 1) V -Bi2O2S is added to bismuth nitrate solution;

[0019] Steps 2-3) Add potassium iodide to the mannitol solution and stir to form a potassium iodide solution. Then, add the potassium iodide solution dropwise to the above-mentioned solution containing O. V Bismuth nitrate solution of -Bi2O2S, and pH adjusted with sodium hydroxide to form a second mixture;

[0020] Steps 2-4) The second mixture is then transferred to a heating container for heating, washed, and dried to obtain O. V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

[0021] Further, in step 1-1), the mass concentrations of thiourea and bismuth nitrate dissolved in distilled water are 2.2 g / L to 2.8 g / L and 30 g / L to 35 g / L, respectively; in step 1-1), the mass-to-volume ratio of lithium hydroxide to the mixed solution of thiourea and bismuth nitrate is 35 g / L to 45 g / L; in step 1-2), when the first mixture is transferred to a heating container for heating, the heating temperature is 200℃ to 220℃ and the heating time is 68h to 72h; in step 1-3), when Bi2O2S is calcined under a nitrogen atmosphere, the calcination temperature is 380℃ to 400℃ and the calcination time is 2h to 4h.

[0022] Further, in steps 2-1) and 2-3), the mass concentration of mannitol in the mannitol solution is preferably 15 g / L to 20 g / L; in step 2-4), when the second mixture is transferred to a heating container for heating, the heating temperature is 120℃ to 140℃ and the heating time is 20h to 24h; in step 2-4), after washing and drying, O is obtained. V The drying temperature for Bi2O2S / Bi4O5I2 photocatalytic materials is 60℃~80℃, and the drying time is 10h~12h.

[0023] Further, in step 2-1), the mass-to-volume ratio of bismuth nitrate to mannitol solution is 45 g / L to 50 g / L; in step 2-2), O V The mass-to-volume ratio of Bi₂O₂S to bismuth nitrate solution is 5 g / L to 15 g / L; the mass-to-volume ratio of potassium iodide to mannitol solution in step 2-3) is preferably 15 g / L to 20 g / L; the pH of the second mixture after adjusting the pH with sodium hydroxide in step 2-3) is 9 to 11.

[0024] Furthermore, the O V -Bi2O2S / Bi4O5I2 composite photocatalyst material is suitable for hydrogen peroxide synthesis; the O V The application of Bi2O2S / Bi4O5I2 composite photocatalysts in hydrogen peroxide synthesis specifically includes: ... VThe Bi2O2S / Bi4O5I2 composite photocatalyst material was added to deionized water containing glycerol, stirred in the dark at room temperature, and oxygen was injected to reach adsorption equilibrium. Then, the reaction was carried out for a certain period of time under visible light irradiation and oxygen supply.

[0025] Furthermore, the O V The proportion of the Bi2O2S / Bi4O5I2 composite photocatalyst material added to deionized water containing glycerol is 0.2 g / L to 0.8 g / L; the volume ratio of glycerol to deionized water in the deionized water containing glycerol is 1:30 to 1:10; the reaction time under visible light irradiation and oxygen supply is 20 min to 60 min.

[0026] The beneficial effects of this invention are:

[0027] 1) The O prepared by this invention V -Bi2O2S / Bi4O5I2 photocatalytic materials, by introducing oxygen vacancies, inject additional delocalized electrons into the conduction band, thereby increasing the O2 content. V -Carrier density and mobility of Bi2O2S / Bi4O5I2 photocatalytic materials;

[0028] 2) Due to O V - An S-type heterojunction is formed between Bi2O2S and Bi4O5I2, and strong interfacial interactions are present, which is beneficial to the transport of photogenerated carriers between the complexes, can suppress the recombination of photogenerated electron-hole pairs, and improve photocatalytic activity.

[0029] 3) O V The Bi₂O₂S / Bi₄O₅I₂ photocatalyst possesses locally localized electronic states (composed of Bi₆p orbitals), allowing electrons to be directly excited into the conduction band. Therefore, it exhibits excellent light-harvesting ability and effective separation of photoinduced carriers across a broad spectrum, thereby enhancing the O₂ photocatalysis efficiency. V -Photocatalytic performance of Bi2O2S / Bi4O5I2 photocatalytic materials;

[0030] 4) The O prepared by this invention V -Bi2O2S / Bi4O5I2 photocatalytic material has the advantages of being green and economical, having good stability and high catalytic activity. It is a novel composite photocatalytic material with a novel structure and excellent performance. Attached Figure Description

[0031] Appendix Figure 1 O prepared in Example 5 V SEM image of -Bi2O2S / Bi4O5I2.

[0032] Appendix Figure 2 O prepared in Example 5 VTEM image of Bi2O2S / Bi4O5I2.

[0033] Appendix Figure 3 O prepared in Example 5 V HRTEM image of -Bi2O2S / Bi4O5I2.

[0034] Appendix Figure 4 It is pure Bi2O2S (prepared in Example 1), O V -Bi2O2S (prepared in Example 2), Bi4O5I2 (prepared in Example 3), O V XRD pattern of the Bi2O2S / Bi4O5I2 composite visible light catalytic material (prepared in Examples 4, 5, and 6).

[0035] Appendix Figure 5 This invention provides pure Bi₂O₂S (prepared in Example 1) and O. V -Bi2O2S (prepared in Example 2), Bi4O5I2 (prepared in Example 3), O V Comparison of the efficiency of hydrogen peroxide production by the Bi2O2S / Bi4O5I2 composite visible light catalytic material (prepared in Examples 4, 5, and 6) under visible light conditions.

[0036] Appendix Figure 6 For the present invention O V -Bi2O2S (S2 prepared in Example 2), Bi4O5I2 (S3 prepared in Example 3), O V -UV-Vis diffuse reflectance spectrum of the Bi2O2S / Bi4O5I2 (S5 prepared in Example 5) composite visible photocatalytic material.

[0037] Appendix Figure 7 For the present invention O V -Bi2O2S (S2 prepared in Example 2), Bi4O5I2 (S3 prepared in Example 3), O V Photoluminescence spectrum of the Bi2O2S / Bi4O5I2 (S5 prepared in Example 5) composite visible light catalytic material. Detailed Implementation

[0038] A photocatalytic material based on Bi2O2S, the structure of which includes Bi2O2S, oxygen vacancies introduced on Bi2O2S, and an S-shaped heterojunction constructed on Bi2O2S.

[0039] The photocatalytic material based on Bi2O2S is O V -Bi2O2S / Bi4O5I2 composite photocatalytic material; the O VThe Bi₂O₂S / Bi₄O₅I₂ composite photocatalyst increases the number of oxygen vacancies by introducing oxygen vacancies and constructing an S-shaped heterojunction. V -Carrier density and mobility of Bi2O2S / Bi4O5I2 composite photocatalysts; Meanwhile, O V -Bi2O2S / Bi4O5I2 exhibits strong interfacial interactions, which facilitates the transport of photogenerated carriers between the complexes, suppresses the recombination of photogenerated electron-hole pairs, and enhances photocatalytic activity.

[0040] A kind of O V A method for preparing Bi2O2S / Bi4O5I2 composite photocatalytic materials, comprising the following steps:

[0041] Step 1) Preparation of O V -Bi2O2S catalyst;

[0042] Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

[0043] Step 1) Preparation of O V -Bi2O2S, specifically includes the following steps:

[0044] Step 1-1) Dissolve thiourea and bismuth nitrate in distilled water and stir to form a mixed solution of thiourea and bismuth nitrate. Then add lithium hydroxide to the mixed solution of thiourea and bismuth nitrate and stir to form a first mixture.

[0045] Steps 1-2) The first mixture is transferred to a heating container for heating. After heating, the mixture is washed and dried to obtain Bi2O2S. The heating container is preferably a 100 mL high-pressure autoclave lined with polytetrafluoroethylene.

[0046] Steps 1-3) Calcine Bi₂O₂S under a nitrogen atmosphere to obtain O V -Bi2O2S; preferably, Bi2O2S is calcined in a tube furnace under a nitrogen atmosphere to obtain O. V -Bi2O2S.

[0047] Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalyst material, specifically including the following steps:

[0048] Step 2-1) Add bismuth nitrate to mannitol solution and stir to form bismuth nitrate solution; wherein, the mass-volume ratio of bismuth nitrate to mannitol solution is preferably 45g / L to 50g / L, that is, 45g to 50g of bismuth nitrate is added to every 1L of mannitol solution;

[0049] Step 2-2) Take the O prepared in step 1) VBi₂O₂S was added to a bismuth nitrate solution and stirred magnetically; O V The mass-to-volume ratio of Bi₂O₂S to bismuth nitrate solution is 5 g / L to 15 g / L, that is, 5 g to 15 g of O₂S is added to every 1 L of bismuth nitrate solution. V -Bi2O2S;

[0050] Steps 2-3) Add potassium iodide to the mannitol solution and stir to form a potassium iodide solution. After ultrasonic stirring, slowly add the ultrasonically stirred potassium iodide solution dropwise to the above-mentioned solution containing O. V In a bismuth nitrate solution of -Bi2O2S, ultrasonic stirring is performed, and the pH is adjusted with sodium hydroxide to form a second mixture; wherein, the mass-volume ratio of potassium iodide to mannitol solution is preferably 15 g / L to 20 g / L, that is, 15 g to 20 g of potassium iodide is added to every 1 L of mannitol solution.

[0051] Steps 2-4) The second mixture is then transferred to a heating container for heating, washed, and dried to obtain O. V -Bi2O2S / Bi4O5I2 composite photocatalytic material; the heating container is preferably a 100 mL high-pressure autoclave lined with polytetrafluoroethylene.

[0052] In step 1-1), the mass concentrations of thiourea and bismuth nitrate dissolved in distilled water are 2.2 g / L to 2.8 g / L and 30 g / L to 35 g / L, respectively, that is, 2.2 g to 2.8 g of thiourea and 30 g to 35 g of bismuth nitrate are dissolved in 1 L of distilled water.

[0053] In step 1-1), the mass-to-volume ratio of lithium hydroxide to the mixed solution of thiourea and bismuth nitrate is 35 g / L to 45 g / L, that is, 35 g to 45 g of lithium hydroxide is added to every 1 L of the mixed solution of thiourea and bismuth nitrate.

[0054] In step 1-2), when the first mixture is transferred to a heating container for heating, the heating temperature is preferably 200℃~220℃ and the heating time is preferably 68h~72h.

[0055] In steps 1-3), when Bi2O2S is calcined under a nitrogen atmosphere, the preferred calcination temperature is 380℃~400℃ and the preferred calcination time is 2h~4h.

[0056] In step (2), the stirring and magnetic stirring times are preferably 10 min to 30 min, and the ultrasonic stirring time is preferably 20 min to 40 min.

[0057] In steps 2-1) and 2-3), the preferred mass concentration of mannitol in the mannitol solution is 15 g / L to 20 g / L.

[0058] In steps 2-3), the pH after adjusting the pH with sodium hydroxide to form the second mixture is preferably 9-11, and more preferably 10.

[0059] In steps 2-4), when the second mixture is transferred to a heating container for heating, the preferred heating temperature is 120℃~140℃ and the preferred heating time is 20h~24h.

[0060] O is obtained by washing and drying in steps 2-4). V The preferred drying temperature for Bi2O2S / Bi4O5I2 photocatalytic materials is 60℃~80℃, and the preferred drying time is 10h~12h.

[0061] The O V -Bi2O2S / Bi4O5I2 composite photocatalyst material is suitable for hydrogen peroxide synthesis.

[0062] A kind of O V The application of Bi2O2S / Bi4O5I2 composite photocatalysts in hydrogen peroxide synthesis specifically includes: ... V The Bi2O2S / Bi4O5I2 composite photocatalyst material was added to deionized water containing glycerol, stirred in the dark at room temperature, and oxygen was injected to reach adsorption equilibrium. Then, the reaction was carried out for a certain period of time under visible light irradiation and oxygen supply.

[0063] The O V The preferred ratio of the Bi2O2S / Bi4O5I2 composite photocatalyst material added to deionized water containing glycerol is 0.2 g / L to 0.8 g / L, that is, 0.2 g to 0.8 g of composite photocatalyst material is added to every 1 L of deionized water containing glycerol; the preferred volume ratio of glycerol to deionized water is 1:30 to 1:10; the preferred reaction time under visible light irradiation and oxygen supply is 20 min to 60 min.

[0064] The mechanism of this invention is: O V The existence of O V The localized electronic states below the conduction band of Bi₂O₂S (composed of Bi₆p orbitals) facilitate the direct excitation of localized electrons to O₂. V -In the conduction band of Bi2O2S; O V It can act as an electron donor, injecting additional delocalized electrons into the conduction band, thereby increasing carrier density and mobility; furthermore, in O V During the formation of an S-type heterojunction between Bi2O2S and Bi4O5I2, electrons migrate from Bi4O5I2 to O. V -Bi2O2S, when O VWhen the Bi₂O₂S surface reaches equilibrium, an electron depletion layer forms on the surface, while an electron accumulation layer forms on the Bi₄O₅I₂ surface near the interface; electron loss leads to O V -Bi₂O₂S band bends upwards, while Bi₄O₅I₂ band bends downwards; simultaneously, Bi₄O₅I₂ and O V The internal electric field between Bi₂O₂S and Bi₄O₅I₂ more quickly separates electron-hole pairs with high redox capabilities; then, under visible light, photogenerated electrons easily move from the CB (conduction band) of Bi₄O₅I₂ to the O₂ region. V -Bi2O2S has a VB (valence band); therefore, electrons interact with dissolved O2 in water to produce H2O2.

[0065] The photocatalytic material based on Bi2O2S prepared in this invention overcomes the shortcomings of existing technologies, such as poor interface quality, narrow band structure, low light absorption capacity, and rapid carrier recombination. The O2O2S photocatalytic material prepared in this invention... V -Bi2O2S / Bi4O5I2 composite photocatalysts, by introducing oxygen vacancies and constructing S-type heterojunctions, thereby increasing O2 V -Carrier density and mobility of Bi2O2S / Bi4O5I2 composite photocatalysts; Meanwhile, O V -Bi2O2S / Bi4O5I2 exhibits strong interfacial interactions, which facilitates the transport of photogenerated carriers between the complexes, suppresses the recombination of photogenerated electron-hole pairs, and enhances photocatalytic activity.

[0066] The present invention will be described in detail below with reference to the embodiments, so that those skilled in the art can better understand the present invention. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the materials and instruments used in the following embodiments are commercially available, and the equipment used is conventional equipment. Example 1

[0067] Thiourea and bismuth nitrate were dissolved in distilled water and stirred to form a mixed solution of thiourea and bismuth nitrate. The mass concentrations of thiourea and bismuth nitrate to distilled water were 2.53 g / L and 32.4 g / L, respectively, meaning that 2.53 g of thiourea and 32.4 g of bismuth nitrate were dissolved in 1 L of distilled water. The mass-volume ratio of lithium hydroxide in the mixed solution of thiourea and bismuth nitrate was 40 g / L. Subsequently, lithium hydroxide was added to the mixed solution of thiourea and bismuth nitrate and stirred. After stirring, the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and heated at 200 °C for 72 h. After washing and drying, Bi2O2S (labeled as S1) was obtained. Example 2

[0068] The Bi₂O₂S catalyst prepared in Example 1 was calcined in a tube furnace at 400°C for 4 h under a nitrogen atmosphere to prepare O₂. V -Bi2O2S catalyst (labeled as S2). Example 3

[0069] Bismuth nitrate was added to a mannitol solution and stirred to form a bismuth nitrate solution, wherein the mass-to-volume ratio of bismuth nitrate to mannitol solution was 48.5 g / L. Potassium iodide was added to a mannitol solution and stirred for 20 min to form a potassium iodide solution. After ultrasonic stirring for 30 min, the ultrasonically stirred potassium iodide solution was slowly added dropwise to the above bismuth nitrate solution, and ultrasonically stirred for 30 min. The pH was adjusted to 10 with sodium hydroxide to form a mixture. The preferred mass-to-volume ratio of potassium iodide to mannitol solution in the potassium iodide solution was 16.6 g / L. The mass concentration of mannitol in the mannitol solution used was 18.2 g / L. The mixture was then transferred to a 100 mL polytetrafluoroethylene-lined autoclave and heated at 140 °C for 24 h. After washing, it was dried at 60 °C to obtain Bi4O5I2 (labeled as S3). Example 4

[0070] Bismuth nitrate was added to a mannitol solution and stirred to form a bismuth nitrate solution, wherein the mass-to-volume ratio of bismuth nitrate to mannitol solution was 48.5 g / L; the O prepared in Example 2 was then added to the mannitol solution. V -Bi₂O₂S was added to a bismuth nitrate solution, wherein the O prepared in Example 2... V The mass-to-volume ratio of Bi₂O₂S to bismuth nitrate solution was 5 g / L. Potassium iodide was added to mannitol solution and stirred for 20 min to form a potassium iodide solution. After ultrasonic stirring for 30 min, the potassium iodide solution was slowly added dropwise to the above solution containing O₂O₂S. V Bismuth nitrate solution of -Bi₂O₂S was ultrasonically stirred for 30 min, and the pH was adjusted to 10 with sodium hydroxide to form a mixture. The mass-to-volume ratio of potassium iodide to mannitol solution in the potassium iodide solution was 16.6 g / L; the mannitol concentration in the mannitol solution was 18.2 g / L. The mixture was then transferred to a 100 mL PTFE-lined autoclave and heated at 140 °C for 24 h. After washing, it was dried at 60 °C to obtain O₂. V -Bi2O2S / Bi4O5I2 (labeled as S4). Example 5

[0071] Bismuth nitrate was added to a mannitol solution and stirred to form a bismuth nitrate solution, wherein the mass-to-volume ratio of bismuth nitrate to mannitol solution was 48.5 g / L; the O prepared in Example 2 was then added to the mannitol solution. V -Bi₂O₂S was added to a bismuth nitrate solution, wherein the O prepared in Example 2...V The mass-to-volume ratio of Bi₂O₂S to bismuth nitrate solution is 10 g / L. Potassium iodide is added to mannitol solution and stirred for 20 min to form a potassium iodide solution. After ultrasonic stirring for 30 min, the potassium iodide solution is slowly added dropwise to the above solution containing O₂O₂S. V Bismuth nitrate solution of -Bi₂O₂S was ultrasonically stirred for 30 min, and the pH was adjusted to 10 with sodium hydroxide to form a mixture. The mass-to-volume ratio of potassium iodide to mannitol solution in the potassium iodide solution was 16.6 g / L; the mannitol concentration in the mannitol solution was 18.2 g / L. The mixture was then transferred to a 100 mL PTFE-lined autoclave and heated at 140 °C for 24 h. After washing, it was dried at 60 °C to obtain O₂. V -Bi2O2S / Bi4O5I2 (labeled as S5). Example 6

[0072] Bismuth nitrate was added to a mannitol solution and stirred to form a bismuth nitrate solution, wherein the mass-to-volume ratio of bismuth nitrate to mannitol solution was 48.5 g / L; the O prepared in Example 2 was then added to the mannitol solution. V -Bi₂O₂S was added to a bismuth nitrate solution, wherein the O prepared in Example 2... V The mass-to-volume ratio of Bi₂O₂S in the bismuth nitrate solution is 15 g / L; potassium iodide is added to mannitol solution and stirred for 20 min to form a potassium iodide solution, which is then ultrasonically stirred for 30 min. Subsequently, the potassium iodide solution is slowly added dropwise to the above solution containing O₂O₂S. V Bismuth nitrate solution of -Bi₂O₂S was ultrasonically stirred for 30 min, and the pH was adjusted to 10 with sodium hydroxide to form a mixture. The mass-to-volume ratio of potassium iodide to mannitol solution in the potassium iodide solution was 16.6 g / L; the mannitol concentration in the mannitol solution was 18.2 g / L. The mixture was then transferred to a 100 mL PTFE-lined autoclave and heated at 140 °C for 24 h. After washing, it was dried at 60 °C to obtain O₂. V -Bi2O2S / Bi4O5I2 (labeled as S6).

[0073] Appendix Figure 1 O prepared in Example 5 V SEM images of Bi2O2S / Bi4O5I2 are attached. Figure 1 It can be seen that the prepared O V -Bi2O2S / Bi4O5I2 composite visible light photocatalyst material is in the form of nanosheets.

[0074] Appendix Figure 2 O prepared in Example 5 V TEM image of Bi2O2S / Bi4O5I2, from the attached image. Figure 2 It can be seen that the nanosheets have a planar spacing of 0.277 nm, corresponding to the (130) plane of Bi₂O₂S; in addition, the lattice spacing of 0.310 nm is attributed to Bi₄O₅I₂, corresponding to the (-4-11) plane; O V A compact interface is formed between -Bi2O2S and Bi4O5I2.

[0075] Appendix Figure 3 O prepared in Example 5 V HRTEM image of -Bi2O2S / Bi4O5I2, from the attached... Figure 3 It can be seen that O V The discontinuous and blurred crystal fringes of the -Bi2O2S / Bi4O5I2 composite visible light photocatalyst material indicate structural defects, leading to incomplete and disordered lattice, confirming the enrichment of O. V As an active site for generation.

[0076] Appendix Figure 4 It is pure Bi2O2S (prepared in Example 1), O V -Bi2O2S (prepared in Example 2), Bi4O5I2 (prepared in Example 3), O V XRD patterns of the Bi2O2S / Bi4O5I2 (prepared in Examples 4, 5, and 6) composite visible light photocatalysts, as shown in the attached diagram. Figure 4 It can be seen that Bi2O2S material exhibits typical characteristic diffraction peaks at 14.88°, 24.23°, 27.42°, 29.96°, 32.29°, 32.40°, 32.78°, and 36.19°, corresponding to (020), (110), (120), (040), (130), (031), (101), and (121) of Bi2O2S; Bi2O2S and O V -Bi₂O₂S has the same peak profile; O V The peak intensity of -Bi₂O₂S is lower, and the peak shifts to a higher angle than that of Bi₂O₂S. This is due to the lower peak intensity of O₂O₂S. V The structural changes are due to surface disorder; the XRD spectrum of Bi4O5I2 shows typical diffraction peaks at 28.8°, matching the standard Bi4O5I2 crystal phase (-4-11); in O V Diffraction peaks can be observed in the -Bi2O2S / Bi4O5I2 photocatalyst, indicating that O V -Bi₂O₂S has been effectively doped into Bi₄O₅I₂; O V The peak of -Bi2O2S / Bi4O5I2 shifts to a higher angle relative to Bi4O5I2 because O V -Interfacial interaction between Bi2O2S material and Bi4O5I2. Example 7

[0077] Take 20 mg Bi2O2S (S1 prepared in Example 1) and 20 mg O V -Bi2O2S (S2 prepared in Example 2), 20 mg Bi4O5I2 (S3 prepared in Example 3), 20 mg O V -Bi2O2S / Bi4O5I2 (S4 prepared in Example 4), 20 mg O V -Bi2O2S / Bi4O5I2 (S5 prepared in Example 5) and 20 mg O V Bi₂O₂S / Bi₄O₅I₂ (S₆ prepared in Example 6) were each separately added to 50 mL of deionized water containing glycerol to form six mixed solutions for the synthesis of hydrogen peroxide. The volume ratio of glycerol to deionized water in the glycerol-containing deionized water was 1:20. Oxygen was injected into each mixed solution for hydrogen peroxide synthesis under dark conditions and the mixture was stirred for 30 min. The resulting mixtures were then subjected to a photocatalytic reaction under visible light for 30 min. After the reaction, 10 μL aliquots were taken and the photocatalyst was filtered through a 0.22 μm cellulose membrane. The H₂O₂ production rate was determined by iodometric titration. The results are shown below. Figure 5 As shown.

[0078] Appendix Figure 5 This invention provides pure Bi₂O₂S (prepared in Example 1) and O. V -Bi2O2S (prepared in Example 2), Bi4O5I2 (prepared in Example 3), O V A comparison of the efficiency of the Bi2O2S / Bi4O5I2 composite visible light photocatalyst (prepared in Examples 4, 5, and 6) in producing hydrogen peroxide under visible light conditions is shown in the attached figure. Figure 5 It can be seen that after 30 minutes of light exposure, the O prepared in Example 5 of this invention (S5) V The hydrogen peroxide production efficiency of (Bi₂O₂S / Bi₄O₅I₂) is highest under visible light conditions, which indicates that the present invention O V -Bi2O2S / Bi4O5I2 composite photocatalysts can effectively synthesize hydrogen peroxide.

[0079] Appendix Figure 6 For the present invention O V -Bi2O2S (S2 prepared in Example 2), Bi4O5I2 (S3 prepared in Example 3), O V The UV-Vis diffuse reflectance spectrum of the Bi2O2S / Bi4O5I2 (S5 prepared in Example 5) composite visible photocatalyst material is shown in the attached... Figure 6 It can be seen that S5 exhibits a broader light absorption spectrum than S3, which indicates that OV The combination of Bi₂O₂S and Bi₄O₅I₂ to form an S-shaped heterojunction can enhance the light absorption of the composite material; simultaneously, the O₂ content can be determined using the Tauc method. V Band structures of Bi2O2S and Bi4O5I2.

[0080] Appendix Figure 7 For the present invention O V -Bi2O2S (S2 prepared in Example 2), Bi4O5I2 (S3 prepared in Example 3), O V The photoluminescence spectrum of the Bi2O2S / Bi4O5I2 (S5 prepared in Example 5) composite visible light photocatalyst material is obtained from the attached... Figure 7 It can be seen that S5 has the lowest PL strength, indicating that O V - The combination of Bi2O2S and Bi4O5I2 to form an S-type heterojunction reduces photogenerated carrier recombination.

Claims

1. A photocatalytic material based on Bi2O2S, characterized in that... This includes Bi2O2S, oxygen vacancies introduced on Bi2O2S, and an S-type heterostructure constructed on Bi2O2S; the Bi2O2S-based photocatalytic material is O V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

2. The photocatalytic material based on Bi2O2S according to claim 1, characterized in that: The O V The preparation methods of Bi2O2S / Bi4O5I2 composite photocatalytic materials include: Step 1) Preparation of O V -Bi2O2S catalyst; Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

3. The photocatalytic material based on Bi2O2S according to claim 2, characterized in that: Step 1) Preparation of O V -Bi2O2S, specifically including: Step 1-1) Dissolve thiourea and bismuth nitrate in distilled water and stir to form a mixed solution of thiourea and bismuth nitrate. Then add lithium hydroxide to the mixed solution of thiourea and bismuth nitrate and stir to form a first mixture. Step 1-2) The first mixture is transferred to a heating container for heating. After heating, the mixture is washed and dried to obtain Bi2O2S. Steps 1-3) Calcine Bi₂O₂S under a nitrogen atmosphere to obtain O V -Bi2O2S.

4. The photocatalytic material based on Bi2O2S according to claim 2, characterized in that... Step 2) Preparation of O V -Bi2O2S / Bi4O5I2 composite photocatalytic materials, specifically including: Step 2-1) Add bismuth nitrate to the mannitol solution and stir to form a bismuth nitrate solution; Step 2-2) Take the O prepared in step 1) V -Bi2O2S is added to bismuth nitrate solution; Steps 2-3) Add potassium iodide to the mannitol solution and stir to form a potassium iodide solution. Then, add the potassium iodide solution dropwise to the above-mentioned solution containing O. V Bismuth nitrate solution of -Bi2O2S, and pH adjusted with sodium hydroxide to form a second mixture; Steps 2-4) The second mixture is then transferred to a heating container for heating, washed, and dried to obtain O. V -Bi2O2S / Bi4O5I2 composite photocatalytic material.

5. A photocatalytic material based on Bi2O2S according to claim 3, characterized in that... In step 1-1), the mass concentrations of thiourea and bismuth nitrate dissolved in distilled water are 2.2 g / L to 2.8 g / L and 30 g / L to 35 g / L, respectively; in step 1-1), the mass-to-volume ratio of lithium hydroxide to the mixed solution of thiourea and bismuth nitrate is 35 g / L to 45 g / L; in step 1-2), when the first mixture is transferred to a heating container for heating, the heating temperature is 200℃ to 220℃ and the heating time is 68h to 72h; in step 1-3), when Bi2O2S is calcined under a nitrogen atmosphere, the calcination temperature is 380℃ to 400℃ and the calcination time is 2h to 4h.

6. A photocatalytic material based on Bi2O2S according to claim 4, characterized in that... In steps 2-1) and 2-3), the mannitol concentration in the mannitol solution is 15 g / L to 20 g / L; in step 2-4), when the second mixture is transferred to a heating container for heating, the heating temperature is 120℃ to 140℃ and the heating time is 20h to 24h; in step 2-4), O is obtained after washing and drying. V The drying temperature for Bi2O2S / Bi4O5I2 photocatalytic materials is 60℃~80℃, and the drying time is 10h~12h.

7. A photocatalytic material based on Bi2O2S according to claim 4, characterized in that... In step 2-1), the mass-to-volume ratio of bismuth nitrate to mannitol solution is 45 g / L to 50 g / L; in step 2-2), O V The mass-to-volume ratio of Bi₂O₂S to bismuth nitrate solution is 5 g / L to 15 g / L; the mass-to-volume ratio of potassium iodide to mannitol solution in step 2-3) is 15 g / L to 20 g / L; and the pH of the second mixture after adjusting the pH with sodium hydroxide in step 2-3) is 9 to 11.

8. A photocatalytic material based on Bi2O2S according to any one of claims 1-7, characterized in that... The O V -Bi2O2S / Bi4O5I2 composite photocatalyst material is suitable for hydrogen peroxide synthesis; the O V The application of Bi2O2S / Bi4O5I2 composite photocatalysts in hydrogen peroxide synthesis specifically includes: ... V The Bi2O2S / Bi4O5I2 composite photocatalyst material was added to deionized water containing glycerol, stirred in the dark at room temperature, and oxygen was injected to reach adsorption equilibrium. Then, the reaction was carried out for a certain period of time under visible light irradiation and oxygen supply.

9. A photocatalytic material based on Bi2O2S according to claim 8, characterized in that... The O V The proportion of the Bi2O2S / Bi4O5I2 composite photocatalyst material added to deionized water containing glycerol is 0.2 g / L to 0.8 g / L; the volume ratio of glycerol to deionized water in the deionized water containing glycerol is 1:30 to 1:10; the reaction time under visible light irradiation and oxygen supply is 20 min to 60 min.

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