Preparation method of sulfur defect regulated sulfur-indium-zinc piezoelectric catalyst and application thereof

Abstract

The application discloses a preparation method of a sulfur-defect-regulated sulfur-indium-zinc piezoelectric catalyst and application thereof, and belongs to the field of environmental functional materials and water pollution control technology. Sulfur-acetamide is used as a sulfur source and is used as a precursor together with zinc ions and indium ions to perform a hydrothermal reaction. The product of the hydrothermal reaction is calcined at a high temperature of 300-450 DEG C to obtain the piezoelectric catalyst. The sulfur-acetamide is used as the sulfur source to prepare the sulfur-indium-zinc piezoelectric material, and the sulfur-indium-zinc piezoelectric material with a micron flower-like structure, a stoichiometric ratio close to an ideal value, a complete crystal structure and stable crystal phases is obtained. Further, the sulfur defects are introduced into the sulfur-indium-zinc piezoelectric material, and the piezoelectric catalytic reaction efficiency can be remarkably improved. Meanwhile, the piezoelectric catalyst can generate hydrogen peroxide in situ, the hydrogen peroxide is activated by an iron source to generate hydroxyl radicals, and the deep degradation of organic pollutants can be realized.

Description

Technical Field

[0001] This invention relates to the field of environmental functional materials and water pollution control technology, specifically to a method for preparing a sulfur defect-regulated indium zinc sulfide piezoelectric catalyst and its application. Background Technology

[0002] With the acceleration of industrialization, a large amount of organic pollutants have entered the aquatic environment. Traditional biological treatment and physical separation methods are difficult to achieve efficient removal of recalcitrant organic pollutants. Traditional Fenton reaction usually relies on the addition of hydrogen peroxide, the reaction conditions are limited to an acidic environment, and iron sludge is easily generated during the reaction process, which increases the difficulty of subsequent treatment and may cause secondary pollution.

[0003] In recent years, piezoelectric catalysis has attracted attention as a novel technology that uses mechanical energy to drive chemical reactions. Piezoelectric materials can generate polarized charges under mechanical strain, thereby driving surface redox reactions and providing a new technical pathway for pollutant degradation. Therefore, it is of great significance to develop a piezoelectric catalytic material with tunable structure, excellent catalytic performance and suitability for environmental conditions.

[0004] Sulfide semiconductors are considered to be one of the potential piezoelectric catalytic material systems due to their non-centrosymmetric structure and good piezoelectric response characteristics. However, existing research on the regulation of sulfide piezoelectric materials mainly focuses on morphology control or heterostructure construction, lacking systematic research on the relationship between their intrinsic defect structure and piezoelectric catalytic reaction. In particular, there are still problems such as insufficient catalytic activity and unclear reaction pathways in achieving in-situ hydrogen peroxide production and self-Fenton reaction.

[0005] The invention patent with announcement number CN111790404B discloses a defective zinc indium sulfide microsphere visible light photocatalyst, its preparation method, and its application. The preparation method involves heating ZnIn2S4 microspheres to 90-120℃ in a hydrogen atmosphere to obtain the defective zinc indium sulfide microsphere visible light photocatalyst. However, the L-cysteine ​​used in this invention, due to its multifunctional structure, easily undergoes strong coordination with metal ions, introducing more structural defects and local distortions during nucleation and growth. Although these defects can enhance local polarization to some extent, they may also act as recombination centers, affecting the continuity of carrier migration and the stability of piezoelectric response. Therefore, under long-term operation or strong mechanical stimulation conditions, the reproducibility and stability of its piezoelectric catalytic performance are relatively limited. Summary of the Invention

[0006] Indium zinc sulfide (IZS) materials possess a non-centrosymmetric crystal structure, enabling them to generate piezoelectric polarization under external mechanical stimulation, forming directionally distributed polarization charges. However, in uncontrolled IZS materials, the electrons and holes generated by piezoelectricity readily recombine rapidly, resulting in a limited number of effective charge carriers participating in surface reactions and low piezoelectric energy utilization efficiency.

[0007] To address the aforementioned technical problems, this invention provides a method for preparing a sulfur defect-controlled indium zinc sulfide piezoelectric catalyst and its application. The method uses thioacetamide as a sulfur source to prepare the indium zinc sulfide piezoelectric material, and improves its piezoelectric catalytic activity by controlling the sulfur defect structure of the material. Furthermore, this sulfur defect-controlled indium zinc sulfide piezoelectric catalyst is applied to a piezoelectric catalytic self-Fenton system, achieving efficient degradation of organic pollutants without the need for external energy or harsh reaction conditions, thereby overcoming the problems of low catalytic efficiency and limited applicability in existing technologies.

[0008] This invention discloses a method for preparing a sulfur defect-regulated indium zinc sulfide piezoelectric catalyst. The piezoelectric catalyst is a micron-shaped flower structure composed of indium zinc sulfide nanosheets containing sulfur defects. Thioacetamide is used as a sulfur source, and zinc ions and indium ions are used as precursors to carry out a hydrothermal reaction. The product of the hydrothermal reaction is then calcined at a high temperature of 300~450 °C to obtain the piezoelectric catalyst.

[0009] This invention uses thioacetamide as a sulfur source. Compared to some drawbacks of using L-cysteine ​​as a sulfur source in existing technologies, thioacetamide mainly releases sulfur through thermal decomposition under hydrothermal or solvothermal conditions. 2- Not participating in Zn 2+ and In 3+ The coordination process makes the nucleation and growth of zinc sulfide more controllable, and can guide the gradual assembly of zinc ions and indium ions, which is conducive to obtaining a micron flower-like structure with an ideal stoichiometric ratio, complete crystal structure and stable crystal phase.

[0010] In this invention, the hydrothermal reaction yields indium zinc sulfide. During calcination heat treatment in air, oxygen atoms in the air combine with some sulfur atoms to form SO2, thereby creating sulfur defects. These sulfur defects cause localized lattice distortion and asymmetric charge distribution, forming a defect-induced built-in electric field within the material. Under mechanical excitation, this built-in electric field synergistically works with the piezoelectric polarization field to significantly suppress bulk recombination behavior of polarized charge carriers, prolong the effective lifetime of electrons and holes, and improve the migration efficiency of piezoelectric polarization charges to the material surface.

[0011] Furthermore, in the hydrothermal reaction process, the molar ratio of thioacetamide to zinc ions, indium ions, and water is 2:0.5:1:1389~2780.

[0012] The chemical equation for the reaction of thioacetamide with zinc and indium ions during the hydrothermal reaction is as follows: Zn 2+ +2In 3+ +4S 2- →ZnIn2S4; In the above reaction process, each component reacts according to the above molar ratio, and the amount of water can be adjusted.

[0013] Furthermore, the zinc ions are selected from zinc chloride, zinc acetate, and... Zinc nitrate The indium ions are selected from indium trichloride tetrahydrate and indium nitrate.

[0014] Note: The precursor combination of the present invention can be flexibly selected. The core is any appropriate combination of zinc ion source, indium ion source and thioacetamide (sulfur source), as follows: zinc ions can be any one of zinc chloride, zinc acetate and zinc nitrate; indium ions can be any one of indium trichloride tetrahydrate and indium nitrate. The selected substances are combined with thioacetamide in the aforementioned molar ratio to serve as the reaction precursor of the present invention. All feasible combinations are applicable to this preparation method, and will not be described in detail here.

[0015] The present invention also provides a specific process for the above preparation method, including the following steps: S1. Mix thioacetamide, zinc ions, indium ions and water according to the specified ratio, stir to form a suspension, and carry out a hydrothermal reaction at 160~200℃ for 1.5~2.5h. S2. Wash and dry the reaction product obtained in S1 at a temperature of 50-80°C for 12-24 hours. S3. The product dried in S2 is placed in a muffle furnace and calcined for 0.5-1.5 hours. The product obtained is the sulfur defect-regulated indium zinc sulfide piezoelectric catalyst.

[0016] Furthermore, in S1, the stirring is carried out using a magnetic stirrer at a speed of 500-600 r / min.

[0017] Note: By controlling the stirring rate, zinc chloride, indium trichloride tetrahydrate, and thioacetamide can be fully dispersed in deionized water to form a uniform and stable suspension. This prevents excessively high local concentrations from causing uneven growth of indium thiosulfate crystal nuclei and irregular product morphology, laying the foundation for the subsequent controllable introduction of sulfur defects.

[0018] Furthermore, in S1, the hydrothermal reaction is carried out at a temperature of 180°C for a time of 2 hours.

[0019] Note: The hydrothermal reaction conditions of 180℃ and 2h are conducive to the efficient and stable decomposition of thioacetamide to produce sulfur. 2-The optimal temperature and time are crucial; when the hydrothermal reaction temperature is below 160℃, the decomposition rate of thioacetamide is too slow, S 2- Insufficient concentration leads to incomplete reaction, leaving unreacted precursors in the product, resulting in incomplete crystal growth of indium sulfide (ZNSSF) and affecting subsequent sulfur defect control. When the hydrothermal reaction temperature exceeds 200℃, thioacetamide decomposes rapidly, leading to sulfur degradation. 2- Excessive concentration can lead to rapid agglomeration and uneven growth of indium sulfide (ILS) crystal nuclei, damaging the micron-like flower structure and even generating impurity phases. When the hydrothermal reaction time is less than 1.5 hours, the reaction is incomplete, resulting in low product purity and numerous ILS crystal phase defects. If the hydrothermal reaction time is greater than 2.5 hours, ILS crystals grow excessively, and the crystal structure is prone to distortion, which in turn affects the piezoelectric polarization performance of the ILS piezoelectric catalyst regulated by sulfur defects.

[0020] Furthermore, in S2, the washing method is as follows: water and ethanol are used as solvents to wash the reaction product sequentially; the drying temperature is 60°C and the time is 12 hours.

[0021] Note: The sequential washing with water and ethanol aims to remove residual soluble impurities (such as unreacted precursors and salts formed in the reaction) and adsorbed organic matter from the surface of the reaction product, preventing residual impurities from affecting the subsequent calcination process and the formation of sulfur defects. The optimal drying conditions of 60℃ and 12h are the best drying temperature and time for the reaction product, ensuring thorough removal of moisture and ethanol. Drying below 50℃ or for less than 12h will result in incomplete drying, allowing residual moisture to react with sulfur atoms, leading to excessive and disordered sulfur defects, and damaging the crystals. Regarding structural stability, when the drying temperature exceeds 80℃ or the drying time exceeds 24 hours, on the one hand, the excessively high temperature will cause the reaction products to be oxidized prematurely, introducing unnecessary oxygen defects and interfering with the controllable regulation of sulfur defects. On the other hand, the excessively long drying time will cause the reaction product particles to undergo irreversible agglomeration. The particles will form a tight packing due to the interaction of surface hydroxyl groups, resulting in uneven heat transfer and obstructed gas diffusion during subsequent calcination. This will not only further aggravate the uneven distribution of sulfur defects, but also cause excessive volatilization of sulfur elements in some areas due to local overheating, causing the number of sulfur defects to deviate from the expected control range.

[0022] Furthermore, in S3, the calcination temperature is 400°C and the time is 1 hour.

[0023] Note: Calcination at 400℃ for 1 hour represents the optimal calcination temperature and time. Under these conditions, oxygen atoms in the air can react with some sulfur atoms in the indium sulfide (ILS) crystal, generating SO2 gas that escapes from the ILS crystal surface. This results in uniformly distributed sulfur defects within the ILS crystal without damaging its main crystal structure and micron-like morphology. When the calcination temperature is below 300℃, the reaction rate between oxygen and sulfur atoms is too slow, resulting in insufficient sulfur defect generation. This makes it difficult to form an effective defect-induced built-in electric field, suppress carrier recombination, and significantly improve sulfur defect regulation. The piezoelectric catalytic performance of indium zinc piezoelectric catalysts is affected by several factors. When the calcination temperature exceeds 450℃, the oxidation reaction becomes too vigorous, resulting in the oxidation and removal of a large number of sulfur atoms. This leads to an excess of sulfur defects, causing severe distortion of the indium zinc sulfide crystal structure and resulting in the loss of the piezoelectric response characteristics of the sulfur defect-controlled indium zinc sulfide piezoelectric catalyst. When the calcination time is less than 0.5 h, the number of sulfur defects is small, the built-in electric field effect is weak, and the suppression effect on carrier recombination is limited. When the calcination time is greater than 1.5 h, the excess of sulfur defects leads to intensified lattice distortion and the formation of carrier recombination centers, which in turn reduces the catalytic performance of the sulfur defect-controlled indium zinc sulfide piezoelectric catalyst.

[0024] On the other hand, the present invention also provides the application of the sulfur defect-regulated indium zinc sulfide piezoelectric catalyst prepared in the first aspect above in piezoelectric catalytic hydrogen peroxide production and self-Fenton removal of organic matter.

[0025] The sulfur-defect-regulated indium zinc sulfide piezoelectric catalyst prepared in this invention possesses internal defects. These sulfur defects alter the coordination environment of adjacent metal cations, forming electron-rich metal active centers. Driven by piezoelectric polarization, the surface-rich electrons preferentially participate in the stepwise reduction reaction of dissolved oxygen, promoting the in-situ generation of superoxide radicals and hydrogen peroxide. This achieves in-situ hydrogen peroxide production without the need for an external power source or oxidant. Furthermore, the in-situ generated hydrogen peroxide is activated by an iron source to produce hydroxyl radicals, which can efficiently oxidize and decompose organic pollutants. Using this sulfur-defect-regulated indium zinc sulfide piezoelectric catalyst in piezoelectric catalytic hydrogen peroxide production and Fenton removal of organic matter enables the deep degradation of pollutants.

[0026] Furthermore, the organic matter is a recalcitrant organic matter, which is one or more of sulfamethoxazole, tetracycline, and methylene blue.

[0027] Note: This invention enables the efficient degradation of sulfamethoxazole, tetracycline, methylene blue, etc., due to the sulfur defect-regulated piezoelectric properties of the indium sulfide-zinc piezoelectric catalyst. This catalyst generates hydroxyl radicals through in-situ hydrogen peroxide production, efficiently disrupting the molecular structure of sulfamethoxazole, tetracycline, methylene blue, etc., degrading them into harmless CO2, H2O, and inorganic ions. This demonstrates the practicality and versatility of this sulfur defect-regulated indium sulfide-zinc piezoelectric catalyst in the treatment of recalcitrant organic wastewater, and provides reliable experimental evidence for its application in actual industrial wastewater treatment. Of course, besides degrading the aforementioned recalcitrant organics, the sulfur defect-regulated indium sulfide-zinc piezoelectric catalyst of this invention also exhibits excellent degradation effects on other common organic pollutants, which will not be elaborated upon here.

[0028] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects: First, this invention uses thioacetamide as a sulfur source to prepare indium zinc sulfide piezoelectric materials, obtaining indium zinc sulfide piezoelectric materials with a near-ideal stoichiometry, complete crystal structure, and stable micron-sized flower-like structure. Furthermore, by introducing sulfur defects into this indium zinc sulfide piezoelectric material, the separation efficiency and utilization efficiency of piezoelectric polarization charge under mechanical excitation conditions are effectively improved, the bulk recombination of polarization carriers is reduced, and more electrons and holes generated by piezoelectricity can participate in surface reactions, thereby significantly improving the efficiency of piezoelectric catalytic reactions.

[0029] Secondly, the sulfur defect-regulated indium zinc sulfide piezoelectric catalyst prepared in this invention can be used in piezoelectric catalytic hydrogen peroxide production and Fenton removal of organic matter without the need for an external power source or external hydrogen peroxide. The dissolved oxygen is reduced in situ on the surface of the piezoelectric catalyst through the piezoelectric effect, and hydrogen peroxide is stably generated. This avoids the increased operating costs and secondary pollution problems caused by the addition of external oxidants in the traditional Fenton system.

[0030] Third, this invention achieves the regulation of piezoelectric catalytic performance through defect engineering, and can systematically regulate the crystal structure, electronic structure and interfacial reaction behavior of the material. The preparation method is highly controllable, easy to prepare in batches, and has good prospects for industrial application. Attached Figure Description

[0031] Figure 1 These are the XRD patterns of the catalysts in Examples 1-4 of this invention and uncalcined ZIS; Figure 2 These are SEM images of the catalyst and uncalcined ZIS in Example 3 of the present invention; wherein, a and b are SEM images of ZIS at a scale of 1 μm and 500 nm, respectively, and c and d are SEM images of ZIS-Vs-400 at a scale of 1 μm and 500 nm, respectively. Figure 3The XRD patterns of the catalyst of Example 3 of the present invention and uncalcined ZIS are shown. Figure 4 These are the XPS full spectrum of the catalyst of Example 3 of the present invention and uncalcined ZIS, as well as the XPS spectra of Zn, In and S elements; wherein, a is the XPS full spectrum of the catalyst of Example 3 and uncalcined ZIS, b is the XPS spectrum of Zn element, c is the XPS spectrum of In element, and d is the XPS spectrum of S element. Figure 5 These are the EDS spectra of the catalyst of Example 3 of the present invention and uncalcined ZIS; wherein, a is the EDS spectra of uncalcined ZIS and b is the EDS spectra of the catalyst of Example 3. Figure 6 These are the EPR spectra of the catalyst of Example 3 of the present invention and uncalcined ZIS; Figure 7 This is a time-concentration distribution diagram of the hydrogen peroxide production yield of the catalyst in Test Example 1 of the present invention via piezoelectric catalysis; Figure 8 This is a bar chart showing the yield of hydrogen peroxide produced by piezoelectric catalysis of the catalyst in Test Example 2 of the present invention under different calcination and holding time conditions; Figure 9 This is a bar chart of hydrogen peroxide decomposition of the catalyst in Test Example 3 of the present invention; Figure 10 This is a degradation curve of sulfamethoxazole by the catalyst in Test Example 4 of the present invention; Figure 11 This is a graph showing the degradation curves of sulfamethoxazole by the catalyst and different concentrations of divalent iron sources in Test Example 5 of the present invention. Figure 12 This is a degradation curve of sulfamethoxazole by the catalyst and 1mM ferrous iron source in the test example of the present invention. Detailed Implementation

[0032] Example 1: A method for preparing a sulfur defect-modulated indium zinc sulfide piezoelectric catalyst, comprising the following steps: (1) 68.1 mg zinc chloride, 293 mg indium trichloride tetrahydrate and 150 mg thioacetamide were used as precursors, dispersed in 50 mL of deionized water, and stirred with a magnetic stirrer at 500 r / min at room temperature to form a suspension. (2) The resulting suspension was transferred to a polytetrafluoroethylene-lined reactor and reacted at 180°C for 2 hours. (3) After cooling to room temperature, the product is washed with water and ethanol in sequence, and dried in a forced-air drying oven at 60°C for 12 hours to obtain a yellow powder, which is denoted as ZIS; (4) The obtained yellow powder is placed in a muffle furnace and heated to 300°C at a rate of 5°C / min, and kept at the temperature for 1 hour for calcination. The resulting product is sulfur defect-controlled zinc indium sulfide powder, denoted as ZIS-Vs-300.

[0033] Example 2: The difference from Example 1 is that the calcination temperature in step (4) is 350°C, and the resulting product is denoted as ZIS-Vs-350.

[0034] Example 3: The difference from Example 1 is that the calcination temperature in step (4) is 400℃, and the resulting product is denoted as ZIS-Vs-400.

[0035] Example 4: The difference from Example 1 is that the calcination temperature in step (4) is 450℃, and the product obtained is denoted as ZIS-Vs-450.

[0036] XRD analysis was performed on the products ZIS-Vs-300, ZIS-Vs-350, ZIS-Vs-400, and ZIS-Vs-450 obtained in Examples 1-4, and on uncalcined ZIS. The X-ray diffraction (XRD) characterization results of ZIS-Vs-300, ZIS-Vs-350, ZIS-Vs-400, ZIS-Vs-450, and ZIS and ZIS are as follows: Figure 1 As shown: During the heat treatment process from 300℃ to 450℃, the formation of vacancies did not affect the characteristic peaks of ZIS. ZIS, ZIS-Vs-300, and ZIS-Vs-450 all exhibited similar crystal structures. The basic layered crystal structure of ZIS has good thermal stability. The characteristic diffraction peaks at diffraction angles of 21.5°, 27.4°, and 47.1° correspond to the (006), (102), and (110) crystal planes in the hexagonal structure of ZIS, respectively. During the heat treatment process at 300℃ to 350℃, the XRD diffraction peaks of ZIS-Vs-300 and ZIS-Vs-350 highly overlapped with those of ZIS, with sharp peaks and high intensity, maintaining high crystallinity. This indicates that the calcination temperatures of 300℃ and 350℃ were insufficient to generate a high concentration of sulfur vacancies, and the material maintained a high long-range order. Although this is beneficial for carrier transport, its piezoelectric catalytic activity is low due to the lack of sufficient active sites and defect-induced symmetry breaking. During the heat treatment at 400℃, the diffraction peak intensity of ZIS-Vs-400 showed a significant decrease, reflecting the formation of a high concentration of sulfur vacancies in the lattice. This moderate "structural perturbation" significantly enhanced the non-centrosymmetry of the lattice, thereby increasing the yield of piezoelectric polarization charge. On the other hand, the large number of exposed defect sites provided abundant sites for redox reactions. When the temperature was further increased to 450℃, the main peaks such as (102) broadened dramatically, which meant that excessive energy caused excessive loss of sulfur elements and partial disintegration of the hexagonal phase lattice. At this time, the continuity of charge transport was interrupted, the core structure of the piezoelectric response was destroyed, and the performance deteriorated. Therefore, the calcination temperature of 400°C in Example 3 is the key "activation window" to maximize the piezoelectric catalytic potential of ZnIn2S4 by balancing atomic-scale defects and structural integrity.

[0037] Furthermore, the product ZIS-Vs-400 obtained in Example 3 above was compared and analyzed with ZIS that had not been calcined.

[0038] 1. SEM Analysis: ZIS and ZIS-Vs-400 were observed using a scanning electron microscope (SEM), such as... Figure 2 As shown, it can be clearly observed that both ZIS and ZIS-Vs-400 have a micro-flower-like structure composed of stacked nanolayers. It was also observed that when sulfur atoms escaped and sulfur defects were formed by calcination, the structure of the nanosheets was not destroyed. Among them, the micro-flower structure of ZIS is regular and the interlayer is relatively dense. In contrast, the micro-flower of ZIS-Vs-400 is more wrinkled, looser and has rougher edges. Such a structure is more likely to undergo deformation, which is conducive to the piezoelectric process.

[0039] 2. XRD Analysis: The X-ray diffraction (XRD) characterization results of ZIS and ZIS-Vs-400 are as follows: Figure 3 As shown, the formation of vacancies did not affect the characteristic peaks of ZIS. Both ZIS and ZIS-Vs-400 exhibit similar crystal structures. The characteristic diffraction peaks at diffraction angles of 21.5°, 27.4° and 47.1° correspond to the (006), (102) and (110) crystal planes in the hexagonal structure of ZIS, respectively. The presence of defects slightly reduced the intensity of the diffraction peaks of ZIS-Vs-400, and no new diffraction peaks corresponding to the crystals appeared, which fully demonstrates the successful preparation of ZIS and ZIS-Vs-400.

[0040] 3. XPS Analysis: The X-ray photoelectron spectroscopy (XPS) characterization results of ZIS and ZIS-Vs-400 are as follows: Figure 4As shown, the XPS full spectrum fully demonstrates the presence of Zn, In, and S elements in ZIS and ZIS-Vs-400. In the high-resolution XPS spectrum of Zn 2p, Zn 2p exhibits double peaks at 1045.1 and 1022.1 eV, corresponding to Zn 2p 1 / 2 and Zn 2p 3 / 2 In the high-resolution XPS spectrum of In 3d, In 3d can be decomposed into two peaks at 452.5 and 444.9 eV, which are attributed to In 3d. 3 / 2 and In 3d 5 / 2 In the high-resolution XPS spectrum of S 2p, the S 2p peak of ZIS was decomposed into a doublet with binding energies of 162.8 and 161.6 eV, corresponding to S 2p peaks, respectively. 1 / 2 and S 2p 3 / 2 These characteristics are related to S 2− Consistent with ZIS, the binding energy of S 2p in ZIS-Vs-400 shifts by 0.3 eV towards higher binding energies, which is attributed to the presence of sulfur vacancies and causes slight changes in the binding energies of Zn 2p and In 3d in ZIS-Vs-400.

[0041] 4. EDS Analysis: The energy-dispersive X-ray (EDS) characterization results of ZIS and ZIS-Vs-400 are as follows: Figure 5 As shown, the atomic ratios of Zn / In / S in ZIS and ZIS-Vs-400 are 1 / 1.90 / 3.35 and 1 / 2.01 / 3.26, respectively. This indicates that the calcination process creates sulfur vacancies in ZIS-Vs-400, resulting in a significant change in the atomic ratios.

[0042] 5. EPR Test: The EPR test of ZIS and ZIS-Vs-400 further characterized the presence of sulfur defects, and the results are as follows: Figure 6 As shown, the unpaired electron signal of ZIS-Vs-400 is stronger than that of ZIS, and the number of free charge carriers is increased, which further confirms the formation of sulfur vacancies.

[0043] Example 5: The difference from Example 3 is that zinc nitrate, indium nitrate, and thioacetamide can be used as precursors, or zinc acetate, indium nitrate, and thioacetamide can be used as precursors. This application does not impose any special limitations on these examples; those skilled in the art can select appropriate combinations of zinc ions, indium ions, and thioacetamide.

[0044] Example 6: The difference between this example and Example 3 is that the hydrothermal reaction temperature is 160℃ and the time is 2.5h.

[0045] Example 7: The difference between this example and Example 3 is that the hydrothermal reaction temperature is 200℃ and the time is 1.5h.

[0046] Of course, the temperature of the hydrothermal reaction can be any other temperature within the range of 160~200℃, and the reaction time can be adjusted accordingly, as long as the hydrothermal reaction can proceed normally and be completed. This application does not impose any special limitations on the embodiments.

[0047] Example 8: The difference between this example and Example 3 is that the drying temperature is 50°C and the time is 24 hours.

[0048] Example 9: The difference between this example and Example 3 is that the drying temperature is 80℃ and the time is 12h.

[0049] Example 10: The difference between this example and Example 3 is that the magnetic stirring speed is 600 r / min. In some other specific embodiments, the stirring speed can also be 550 r / min or 580 r / min. This application does not limit the stirring speed.

[0050] It should be noted that, in the embodiments of this application, the calcination temperature is the most important influencing parameter, while the temperature, time and other parameters in the hydrothermal reaction process, as well as the washing and drying of the reaction products obtained from the hydrothermal reaction, do not have a significant impact on the performance of the final piezoelectric catalyst, and we will not analyze them one by one here.

[0051] Example 11: The difference between this example and Example 3 is that the calcination time is 0.5h.

[0052] Example 12: The difference between this example and Example 3 is that the calcination time is 1.5 hours.

[0053] Test Example 1: Performance Test of Catalyst in Producing Hydrogen Peroxide in Pure Water The hydrogen peroxide production performance of ZIS-Vs-300, ZIS-Vs-350, ZIS-Vs-400, ZIS-Vs-450 and ZIS in pure water was tested in Examples 1-4, including the following steps: (1) Add 20 mg of catalyst to 30 mL of deionized water to form a uniform suspension; (2) Stir the suspension at 500 r / min for 20 min; (3) Excite the suspension with 200W and 40kHz ultrasound, and extract 2mL of the reaction solution every 20min; (4) The concentration of generated hydrogen peroxide was measured using a colorimetric ultraviolet spectrophotometer: ① Disperse 10 mg of catalase and 100 mg of N,N-diethyl-p-phenylenediamine in 10 mL of deionized water, and name them solution A and solution B, respectively. ②The mixed solution of disodium hydrogen phosphate (10 mL, 0.1 M) and sodium dihydrogen phosphate (90 mL, 0.1 M) is called solution C; ③ Mix 3 mL of deionized water, 30 µL of solution A, 30 µL of solution B, and 300 µL of solution C thoroughly and name the mixture solution D. ④ When measuring with a UV spectrophotometer, take 1 mL of the reaction solution (a clear solution of the hydrogen peroxide concentration to be measured) from step (3) and add it to solution D. Then shake the mixture thoroughly and measure the absorbance at 551 nm to evaluate the concentration of H2O2 during each reaction period.

[0054] The results are as follows Figure 7 As shown, ZIS-Vs-400 (352 μM) showed the highest improvement, approximately 10 times that of ZIS (34 μM), indicating that the introduction of sulfur defects enhanced the ability of ZIS piezoelectric hydrogen peroxide production.

[0055] Test Example 2: Testing the effect of different calcination holding times on the catalyst's hydrogen peroxide production performance. For ZIS-Vs-400 in Example 3, piezoelectric catalytic hydrogen peroxide production was tested under different calcination holding times (0.5h, 1h, 1.5h). The specific test procedure was the same as that in Test Example 1 above, and will not be repeated here. The test results are as follows: Figure 8 As shown, calcination at 400℃ for different calcination times exhibited high piezoelectric hydrogen peroxide production performance, with the highest performance observed at a holding time of 60 min.

[0056] Test Example 3: Test of the hydrogen peroxide decomposition performance of the catalyst Hydrogen peroxide decomposition tests were performed on ZIS-Vs-400 and ZIS in Example 3. The test method included the following steps: (1) Under conditions without ultrasonic excitation, 20 mg of catalyst powder was mixed with 100 mL of H2O2 of a certain concentration (e.g., 1 mmol / L) to carry out H2O2 decomposition experiment; (2) Extract 2 mL of the reaction solution every 20 min and determine the residual concentration of H2O2; (3) The corresponding H2O2 concentration was detected according to the hydrogen peroxide concentration detection method described in Test Example 1. The calculation formula for the H2O2 decomposition rate is as follows: H2O2 decomposition rate (%) = (1 - C / C0) × 100%; Where C0 is the initial concentration of H2O2, and C is the concentration of H2O2 at different times.

[0057] Test results are as follows Figure 9 As shown, ZIS-Vs-400 and water can generate hydrogen peroxide under ultrasonic conditions, and the in-situ generation of hydrogen peroxide is often accompanied by its in-situ decomposition. Figure 9 The decomposition rate of H2O2 by ZIS-Vs-400 is lower than that of hydrogen peroxide by ZIS. This indicates that the decomposition effect of hydrogen peroxide by ZIS-Vs-400 is much lower than that of ZIS, which is conducive to the continuous accumulation of hydrogen peroxide in the in-situ generation process.

[0058] Test Example 4: Degradation Performance Test of Catalyst for Sulfamethoxazole Using ZIS-Vs-400 in Example 3 on Fe 2+ Iron source and Fe 3+ The degradation performance of sulfamethoxazole in a self-Fenton system composed of an iron source was tested. The test method included the following steps: (1) Add 20 mg of catalyst to 50 mL of sulfamethoxazole solution (10 mg / L) to form a uniform suspension; (2) Stir the suspension at 500 r / min for 30 min, take 2 mL of supernatant every 15 min, and then detect the residual concentration of pollutants by high performance liquid chromatography; (3) Add 1 mM Fe to the suspension respectively 2+ (Ferrous sulfate heptahydrate) and 1 mM Fe 3+ (Ferric sulfate hydrate); (3) The suspension was excited by ultrasound at 200W and 40kHz. 2mL of the reaction solution was extracted every 20min and then the residual concentration of pollutants was detected by high performance liquid chromatography.

[0059] Test results as follows Figure 10 As shown, ZIS-Vs-400 in Example 3 in Fe 2+ Iron source and Fe 3+ In the self-Fenton system composed of iron source, Fe 3+ Ions have a negligible effect on initiating the self-Fenton reaction, compared to Fe. 2+ Ions have a significant effect on initiating the self-Fenton reaction, and the removal rate of sulfamethoxazole can reach 96% within 120 min.

[0060] Test Example 5: Degradation performance of sulfamethoxazole by catalyst and different concentrations of ferrous iron source The degradation performance of ZIS-Vs-400 on sulfamethoxazole in a self-Fenton system composed of different concentrations of ferrous iron sources in Example 3 was tested. The test method included the following steps: (1) Add 20 mg of catalyst to 50 mL of sulfamethoxazole solution (10 mg / L) to form a uniform suspension; (2) Stir the suspension at 500 r / min for 30 min, take 2 mL of supernatant every 15 min, and then detect the residual concentration of pollutants by high performance liquid chromatography; (3) Add different concentrations of Fe to the suspension. 2+ (0.5, 1, 1.5, 2mM); (3) The suspension was excited by ultrasound at 200W and 40kHz. 2mL of the reaction solution was extracted every 20min and then the residual concentration of pollutants was detected by high performance liquid chromatography.

[0061] Test results as follows Figure 11 As shown, ZIS-Vs-400 in Example 3 in Fe 2+ When the concentration of sulfamethoxazole is 1 mM, the ratio of the real-time concentration to the initial concentration of the solution is the smallest, therefore Fe 2+ The optimal concentration of 1 mM of sulfamethoxazole has the best degradation effect. This is because less iron source will result in low utilization of hydrogen peroxide and slow start-up of the Fenton reaction, while excessive iron source will form iron sludge and affect the cyclic transformation of iron valence state during catalysis.

[0062] Test Example 6: Degradation performance test of sulfamethoxazole by catalyst and 1mM ferrous iron source The degradation performance of ZIS-Vs-300, ZIS-Vs-350, ZIS-Vs-400, ZIS-Vs-450, and ZIS in a self-Fenton system composed of a 1 mM ferrous iron source for sulfamethoxazole was tested. The test method included the following steps: (1) Add 20 mg of catalyst to 50 mL of sulfamethoxazole solution (10 mg / L) to form a uniform suspension; (2) Stir the suspension at 500 r / min for 30 min, take 2 mL of supernatant every 15 min, and then detect the residual concentration of pollutants by high performance liquid chromatography; (3) Add 1 mM Fe to the suspension 2+ ; (3) The suspension was excited by ultrasound at 200W and 40kHz. 2mL of the reaction solution was extracted every 20 min and then the residual concentration of pollutants was detected by high performance liquid chromatography.

[0063] Test results as follows Figure 12As shown, in the self-Fenton system composed of a 1mM ferrous iron source, ZIS-Vs-400 exhibited the smallest ratio of real-time concentration to initial concentration of sulfamethoxazole solution. Therefore, ZIS-Vs-400 showed the best degradation effect, and the self-Fenton reaction could be initiated rapidly, achieving a removal rate of 96% for sulfamethoxazole within 120 minutes. This indicates that the presence of an appropriate amount of sulfur defects promotes the participation of electrons in the piezoelectric self-Fenton process, and the activation of hydrogen peroxide is conducive to the generation of active species, thereby achieving efficient degradation of pollutants.

Claims

1. A method for preparing a sulfur-defect-regulated indium-zinc sulfide piezoelectric catalyst, characterized in that, The piezoelectric catalyst is a micron-shaped flower structure composed of sulfur-defect-containing indium zinc sulfide nanosheets. Thioacetamide is used as the sulfur source, and zinc ions and indium ions are used as precursors to carry out a hydrothermal reaction. The product of the hydrothermal reaction is then calcined at a high temperature of 300~450℃ to obtain the piezoelectric catalyst.

2. The method according to claim 1, characterized in that, In the hydrothermal reaction process, the molar ratio of thioacetamide to zinc ions, indium ions, and water is 2:0.5:1:1389~2780.

3. The method according to claim 1, characterized in that, The zinc ions are selected from zinc chloride, zinc acetate, and zinc nitrate, and the indium ions are selected from indium trichloride tetrahydrate and indium nitrate.

4. The method according to claim 1, characterized in that, Includes the following steps: S1. Mix thioacetamide, zinc ions, indium ions and water according to the specified ratio, stir to form a suspension, and carry out a hydrothermal reaction at 160~200℃ for 1.5~2.5h. S2. Wash and dry the reaction product obtained in S1 at a temperature of 50-80°C for 12-24 hours. S3. The product dried in S2 is placed in a muffle furnace and calcined for 0.5-1.5 hours. The product obtained is the sulfur defect-regulated indium zinc sulfide piezoelectric catalyst.

5. The method according to claim 4, characterized in that, In S1, the stirring is carried out using a magnetic stirrer at a speed of 500-600 r / min.

6. The method according to claim 4, characterized in that, In S1, the hydrothermal reaction is carried out at a temperature of 180°C for 2 hours.

7. The method according to claim 4, characterized in that, In S2, the washing method is as follows: water and ethanol are used as solvents to wash the reaction product sequentially; the drying temperature is 60°C and the time is 12 hours.

8. The method according to claim 4, characterized in that, In S3, the calcination temperature is 400℃ and the time is 1 hour.

9. The application of the sulfur defect-modulated indium zinc sulfide piezoelectric catalyst prepared by any one of claims 1 to 8 in piezoelectric catalytic hydrogen peroxide production and self-Fenton removal of organic matter.

10. The application as described in claim 9, characterized in that, The organic matter is a recalcitrant organic matter, which is one or more of sulfamethoxazole, tetracycline, and methylene blue.

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