A method for preparing and applying a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst

Abstract

This invention discloses a method for preparing and applying a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst. The method employs a one-step perovskite conversion process. First, indium chloride, zinc chloride, and TAA are reacted in anhydrous ethanol to obtain ZnIn2S4. Then, the obtained ZnIn2S4, CsBr, and BiBr3 are added to DMSO to prepare a precursor solution, which is then injected into isopropanol to obtain Cs3Bi2Br9 / ZnIn2S4. Finally, the solution is dispersed in deionized water to obtain the Bi-doped ZnIn2S4 / BiOBr photocatalyst. This invention shows significant effectiveness in treating organic dye wastewater, greatly improving wastewater treatment efficiency.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to the preparation method and application of Bi-doped ZnIn2S4 / BiOBrZ type heterojunction photocatalysts. Background Technology

[0002] The development of clean and sustainable energy technologies has become an urgent need. With the successful synthesis of various semiconductor photocatalysts, which can generate electron-hole pairs to initiate redox reactions, photocatalysis technology has great potential in many fields. It can remove harmful gases and organic pollutants, thus becoming a new governance method and receiving increasing attention. Advances in nanotechnology and materials science have made the design and modification of photocatalysts crucial for improving efficiency. Traditional photocatalysts such as titanium dioxide, zinc oxide, and cadmium sulfide have advantages such as chemical stability and low cost, but they also have disadvantages such as narrow spectral response (low utilization of multi-response ultraviolet light energy), high photogenerated carrier recombination rate, and low quantum efficiency, limiting their application and performance improvement. BiOBr has advantages over traditional photocatalysts such as a wide visible light response, high conductivity, and superior quantum efficiency, but it is constrained by problems related to photogenerated carrier recombination, aggregation, and light energy utilization. ZnIn2S4 has advantages such as simple preparation, low cost, and a visible light response band gap, but its performance is limited by photogenerated carrier recombination, low solar energy conversion efficiency, and weak oxidation capacity. Both require improvement to enhance their photocatalytic performance.

[0003] Both BiOBr and ZnIn2S4 can improve photocatalytic rates by constructing heterojunctions. Due to their different band structures, the built-in electric field at the heterojunction interface under illumination causes photogenerated carriers to migrate directionally, reducing recombination; the light absorption range is also expanded, allowing for the capture of more light energy, thus significantly improving the rate in photocatalytic applications, showing superior performance in pollutant treatment and water splitting for hydrogen production. For example, HHSS-NH2@BiOBr / ZnIn2S4 (CN118594576A) and type II heterostructure BiOBr / ZnIn2S4 (CN118807794A) have improved photocatalytic rates by constructing heterojunctions. However, the preparation process of HHSS-NH2@BiOBr / ZnIn2S4 is complex, with multiple reaction steps and strict condition control making it difficult to stabilize quality and performance during industrial production, and the cost is high; its stability is limited, and factors such as temperature, humidity, and pH in the actual environment can easily alter its structure and properties. Although the type II heterostructure BiOBr / ZnIn2S4 has a simple preparation process and good stability, its photogenerated carrier redox ability is weak, which affects the reaction efficiency and results in low efficiency; its light absorption range is narrow, concentrated in a certain band of visible light, and its absorption of other light is weak.

[0004] Therefore, there is an urgent need to propose a preparation method for BiOBr / ZnIn2S4 that can effectively expand the spectral response range of the material, enhance its redox ability, and has simple and efficient synthesis process characteristics, so as to meet the needs of practical applications and overcome the limitations of existing related materials and preparation methods. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of traditional photocatalyst preparation methods, such as cumbersome steps and limited catalytic efficiency, by providing a method for preparing and applying a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst. This method innovatively introduces Bi doping and constructs a ZnIn2S4 / BiOBr Z-type heterojunction structure in terms of material composition. In terms of preparation method, unlike traditional multi-step complex processes, it employs a one-step perovskite conversion method, achieving efficient and stable photocatalyst preparation. This invention shows significant effects in treating organic dye wastewater, greatly improving wastewater treatment efficiency.

[0006] The technical solution of this invention is as follows:

[0007] A method for preparing a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst, comprising the following steps:

[0008] ZnIn2S4 was added to the Cs3Bi2Br9 precursor to prepare Cs3Bi2Br9 / ZnIn2S4 by antisolvent method. Cs3Bi2Br9 / ZnIn2S4 was then dispersed in deionized water to obtain Bi-doped ZnIn2S4 / BiOBr photocatalyst.

[0009] The molar ratio of Bi-doped ZnIn2S4 / BiOBr is BiOBr:ZnIn2S4 = 1:(0.015~0.075);

[0010] Specifically:

[0011] 1) Add indium chloride, zinc chloride and TAA to anhydrous ethanol, stir evenly and transfer to polytetrafluoroethylene reactor, seal and react at 150-170 degrees for 10-14 hours, cool and wash with water and dry to obtain ZnIn2S4.

[0012] The molar ratio of indium chloride, zinc chloride, and thioacetamide is 2:1:4.

[0013] 2) Add the ZnIn2S4, CsBr, and BiBr3 obtained in step 1) to DMSO to prepare a precursor solution. After stirring for 0.5 to 1.0 h, inject the precursor solution into isopropanol and stir for 1 to 3 min. Then centrifuge at 8000 to 10000 rpm / min for 1 to 3 min to separate the yellow precipitate. Wash the precipitate with ethanol, centrifuge, and dry at 50 to 70 °C to obtain Cs3Bi2Br9 / ZnIn2S4.

[0014] The molar ratio of ZnIn2S4 to cesium bromide and bismuth bromide is (0.015–0.75):1.5:1;

[0015] Add 0.0010–0.010 mmol ZnIn2S4 per 10 ml DMSO; the volume ratio is precursor solution: isopropanol = 1:5–10.

[0016] 3) Disperse the Cs3Bi2Br9 / ZnIn2S4 obtained in step 2) into deionized water, stir, centrifuge, and vacuum dry to obtain Bi-doped ZnIn2S4 / BiOBr photocatalyst.

[0017] Add 0.06–0.1 g of Cs3Bi2Br9 / ZnIn2S4 to every 10 mL of deionized water;

[0018] The stirring time mentioned in step 3) is 5 to 15 minutes.

[0019] The Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst prepared by the method is used to degrade Rhodamine B contaminants under visible light irradiation.

[0020] Bi-doped ZnIn2S4 / BiOBr photocatalyst was uniformly dispersed in Rhodamine B aqueous solution and irradiated under visible light for 5–15 minutes.

[0021] The concentration of the Rhodamine B aqueous solution is 20 mg / L; 20 mg of Bi-doped ZnIn2S4 / BiOBr photocatalyst is added to every 20 mL of Rhodamine B aqueous solution.

[0022] The essential features of this invention are:

[0023] This invention successfully synthesized a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst using a one-step perovskite conversion method. This process achieves Bi ion doping while forming a Z-shaped heterojunction, extending the photoresponse range into the infrared region. Compared to standalone BiOBr and ZnIn2S4 photocatalysts, the Bi-doped ZnIn2S4 / BiOBr composite material exhibits superior light absorption, enhanced charge transfer efficiency, and improved photogenerated carrier efficiency.

[0024] The beneficial effects of this invention are:

[0025] (1) The present invention adopts a one-step strategy to synthesize Bi-doped ZnIn2S4 / BiOBr composite material by converting ZnIn2S4 / Cs3Bi2Br9, and simultaneously realizes the construction of Z-type heterojunction and Bi ion doping. This is significantly different from the traditional multi-step, complex and separate preparation method, greatly simplifies the process steps and improves production efficiency.

[0026] (2) The Bi-doped ZnIn2S4 / BiOBr photocatalyst prepared by this invention is low in cost and has a simple and efficient synthesis method. The entire experimental process does not require high-temperature synthesis, which not only reduces energy consumption costs but also lowers the requirements for equipment.

[0027] (3) The Bi-doped ZnIn2S4 / BiOBr prepared by the present invention has a significant effect on the photocatalytic treatment of organic dye wastewater, and completes the degradation of organic dye wastewater within 5 minutes, which greatly improves the efficiency of wastewater treatment.

[0028] (4) The photocatalyst synthesized in this invention has good cycle stability. After five photocatalytic degradation cycles, the photocatalytic degradation effect does not decrease significantly and can be recycled and reused multiple times. Attached Figure Description

[0029] Figure 1 The image shows the XRD pattern of the synthesized photocatalyst, where... Figure 1 (a) is the XRD pattern of ZnIn2S4 synthesized in Example 1. Figure 1 (b) shows the XRD patterns of the Bi-doped ZnIn2S4 / BiOBr photocatalysts synthesized in Examples 1-4.

[0030] Figure 2 Here is a SEM image of the photocatalyst synthesized in Example 1, wherein, Figure 2 (a) is a SEM image of the ZnIn2S4 photocatalyst synthesized in Example 1. Figure 2 (b) is a SEM image of the Bi-doped ZnIn2S4 / BiOBr synthesized in Example 1.

[0031] Figure 3 The graphs show the time-degradation rate of Rhodamine B solution by the ZnIn2S4 and Bi-doped ZnIn2S4 / BiOBr photocatalysts synthesized in Examples 1-4. Detailed Implementation

[0032] The invention will be further explained below with reference to specific implementation examples.

[0033] Example 1:

[0034] (1) Dissolve 1 mmol of indium chloride tetrahydrate (InCl34H2O), 0.5 mmol of zinc chloride (ZnCl2), and 2 mmol of thioacetamide (TAA) in 30 mL of anhydrous ethanol and stir thoroughly for 60 min. Then, transfer the solution to a 50 mL polyvinyl fluoride reactor and react at 160 °C for 12 h. After natural cooling, centrifuge three times with anhydrous ethanol and ultrapure water. The resulting product is dried at 70 °C and ground into a uniform powder to obtain ZnIn2S4.

[0035] (2) Add 0.0045 mmol ZnIn2S4, 0.45 mmol cesium bromide (CsBr) and 0.3 mmol bismuth bromide (BiBr3) to 10 ml dimethyl sulfoxide (DMSO), stir for 60 min, then inject into 50 ml isopropanol and stir at the same time. After stirring for 1 min, centrifuge at 10000 r / min for 3 min to collect the yellow precipitate. Wash the precipitate three times with ethanol and dry at 50 °C to obtain Cs3Bi2Br9 / ZnIn2S4.

[0036] (3) Disperse 0.08g of Cs3Bi2Br9 / ZnIn2S4 into 10ml of water, stir for 10 minutes, centrifuge at 10000r / min for 3 minutes, and vacuum dry the precipitate obtained by centrifugation for 24 hours. The product obtained is Bi-doped ZnIn2S4 / BiOBr photocatalyst, wherein the mass ratio of BiOBr to ZnIn2S4 is 1:0.015 (theoretical value), and is labeled as BOB / ZIS-1.

[0037] During the synthesis of Cs3Bi2Br9, ZnIn2S4 will become Bi-doped ZnIn2S4 when it encounters BiBr3, while Cs3Bi2Br9 will decompose into BiOBr when it encounters water.

[0038] Figure 1 The ZnIn2S4 prepared in (a) matches the standard PDF card (65-2023 very well), proving that ZnIn2S4 was successfully prepared. Figure 1 In (b), the XRD pattern mainly shows the peaks of BiOBr. As the ZnIn2S4 content increases, the XRD peaks of ZnIn2S4 gradually appear, proving that the ZnIn2S4 / BiOBr composite material was successfully prepared.

[0039] Figure 2 (a) is a SEM image of pure ZnIn2S4, showing the flower-like morphology. Figure 2 (b) shows that some nanosheets with a size of 0.507 μm were loaded on the flower-like morphology, proving that BiOBr nanosheets were successfully loaded onto ZnIn2S4.

[0040] Example 2:

[0041] Compared with Example 1, the molar mass of ZnIn2S4 in step 2 was changed to 0 mmol, and the rest was the same as in Example 1. The molar mass ratio of BiOBr to ZnIn2S4 in the synthesized Bi-doped ZnIn2S4 / BiOBr photocatalyst was 1:0, and it was labeled as BOB / ZIS-0.

[0042] Example 3:

[0043] Compared with Example 1, the molar mass of ZnIn2S4 in step 2 was changed to 0.009 mmol, while the rest was the same as in Example 1. The molar mass ratio of BiOBr to ZnIn2S4 in the synthesized Bi-doped ZnIn2S4 / BiOBr photocatalyst was 1:0.03, and it was labeled as BOB / ZIS-2.

[0044] Example 4:

[0045] Compared with Example 1, the molar mass of ZnIn2S4 in step 2 was changed to 0.0018 mmol, while the rest was the same as in Example 1. The molar mass ratio of BiOBr to ZnIn2S4 in the synthesized Bi-doped ZnIn2S4 / BiOBr photocatalyst was 1:0.075, and it was labeled as BOB / ZIS-3.

[0046] A series of experiments were conducted on the Bi-doped ZnIn2S4 / BiOBr photocatalysts obtained in Examples 1, 2, 3, and 4 to catalyze the degradation of organic dyes under visible light. Rhodamine B aqueous solution was used as a model wastewater to evaluate the high photocatalytic activity of the catalyst. The experimental conditions were set as follows: a) 20 mg of Bi-doped ZnIn2S4 / BiOBr photocatalyst was dispersed in 20 mL of a 20 mg / L Rhodamine B aqueous solution and stirred for 30 minutes in the dark to allow Rhodamine B to reach adsorption-desorption equilibrium on the catalyst surface; b) Using a xenon lamp as the light source, 0.5 mL of solution was taken from the reactor every 2.5 min after the lamp was turned on for illumination. During illumination, a 420 nm filter was used to filter out light with wavelengths smaller than this, and the xenon lamp power was 300 W. Samples were taken every 2.5 min, centrifuged, and the change in the UV-Vis absorption peak of Rhodamine B in the solution was monitored until the characteristic absorption peak of Rhodamine B could no longer be detected. The concentration of Rhodamine B in the solution at adsorption equilibrium was defined as C0.

[0047] Depend on Figure 3 It is evident that the Bi-doped ZnIn2S4 / BiOBr photocatalyst exhibits excellent photocatalytic activity, especially with a degradation rate of 96% for BOB / ZIS-1 after 5 minutes of illumination. This further demonstrates that the Bi-doped ZnIn2S4 / BiOBr photocatalyst synthesized in this invention is a very good photocatalyst with promising applications in the field of photocatalysis.

[0048] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing a Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst, characterized in that, The method includes the following steps: 1) Indium chloride, zinc chloride and TAA were added to anhydrous ethanol, stirred and then transferred to a polytetrafluoroethylene reactor. After sealing, the reactor was reacted at 150-170°C for 10-14 hours. After cooling, the reactor was washed with water and dried to obtain ZnIn2S4. The molar ratio of indium chloride, zinc chloride, and thioacetamide is 2:1:

4. 2) Add the ZnIn2S4, CsBr, and BiBr3 obtained in step 1) to DMSO to prepare a precursor solution. After stirring for 0.5 to 1.0 h, inject the precursor solution into isopropanol and stir for 1 to 3 min. Then centrifuge at 8000 to 10000 rpm / min for 1 to 3 min to separate the precipitate. Wash the precipitate with ethanol and dry at 50 to 70 °C to obtain Cs3Bi2Br9 / ZnIn2S4. The molar ratio of ZnIn2S4 to cesium bromide and bismuth bromide is (0.015~0.75):1.5:1; the volume ratio is precursor solution:isopropanol = 1:5~10. 3) Disperse the Cs3Bi2Br9 / ZnIn2S4 obtained in step 2) into deionized water, stir, centrifuge, and vacuum dry to obtain Bi-doped ZnIn2S4 / BiOBr photocatalyst; Add 0.06–0.1 g of Cs3Bi2Br9 / ZnIn2S4 to every 10 mL of deionized water.

2. The preparation method of the Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst as described in claim 1, characterized in that, The stirring time mentioned in step 3) is 5 to 15 minutes.

3. The preparation method of the Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst as described in claim 1, characterized in that, each Add 0.0010–0.010 mmol ZnIn2S4 to 10 ml DMSO.

4. The preparation method of the Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst as described in claim 1, characterized in that, The molar ratio of Bi-doped ZnIn2S4 / BiOBr is BiOBr:ZnIn2S4 = 1:(0.015~0.075).

5. The application of the Bi-doped ZnIn2S4 / BiOBr heterojunction photocatalyst prepared by the method described in claim 1, which degrades Rhodamine B contaminants under visible light irradiation.

6. The application as described in claim 5, characterized in that, Bi-doped ZnIn2S4 / BiOBr photocatalyst was uniformly dispersed in Rhodamine B aqueous solution and irradiated under visible light for 5–15 minutes. The concentration of the Rhodamine B aqueous solution is 20 mg / L; 20 mg of Bi-doped ZnIn2S4 / BiOBr photocatalyst is added to every 20 mL of Rhodamine B aqueous solution.

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