A double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst, a preparation method and application thereof

Abstract

The application discloses a kind of double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst and preparation method and application.The double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 composite photocatalyst, the existence of sulfur vacancy in composite material is confirmed by electron paramagnetic resonance.In addition, scanning electron microscopy, X-ray diffraction and fourier infrared analysis show that these results show that there is interaction between composite material and has close interface contact.In addition, the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 composite photocatalyst prepared by the application has good structural stability, and the characteristics of repeated use greatly reduce the processing cost.Further, the catalyst is low in cost, can quickly decompose and convert chloroquine phosphate in wastewater, greatly improves the efficiency of wastewater treatment, and meets the needs of large-scale industrial application.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalysis technology, and in particular relates to a SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst with double sulfur vacancies, a preparation method and an application thereof. Background Art

[0002] Chloroquine phosphate, a common antiviral drug, is found in wastewater at concentrations ranging from 110 ng / L to 33 μg / L (Environ. Sci. Technol. 2023, 57, 7913−7923). Its residues in water bodies can be toxic to aquatic organisms, affecting their growth, reproduction, and survival, and disrupting the balance of aquatic ecosystems. In recent years, photocatalytic materials have been developed that can break down chloroquine phosphate into harmless water, carbon dioxide, and other small molecules. Under illumination, the photocatalytic reaction initiates rapidly, degrading pollutants in a short period of time, significantly improving treatment efficiency and reducing time and costs. Therefore, the design of novel photocatalytic materials with high catalytic activity, stable structure, and the ability to rapidly generate large amounts of free radicals remains a hot topic.

[0003] Bi2S3 has a band gap of approximately 1.8 eV and can effectively absorb visible light, even having a certain absorption capacity in the near-infrared region. This allows it to utilize the more abundant visible light portion of solar energy for photocatalytic reactions, improving the utilization rate of solar energy and showing great potential in the field of photocatalysis. In practical applications, photogenerated electrons and holes in Bi2S3 are easily recombined, which results in a shorter lifetime of photogenerated carriers, a reduction in the number of effective carriers participating in the photocatalytic reaction, and thus a reduction in photocatalytic efficiency. To overcome this problem, it is usually necessary to compound Bi2S3 with other materials or construct a special structure to promote the separation of photogenerated carriers and improve the stability of the catalyst.

[0004] ZnIn2S4 maintains a certain degree of structural and performance stability, facilitating its long-term use in practical applications. Its bandgap, between 2.06 and 2.85 eV, allows it to absorb visible light. While ZnIn2S4 exhibits moderate photocatalytic activity, its quantum efficiency—the efficiency of converting absorbed photons into chemical energy—is still relatively low compared to ideal, high-efficiency photocatalysts. Further improvement is needed to meet the demands of practical applications. Its properties can be manipulated through composites with other materials, defects, and doping. For example, forming a heterojunction with other semiconductor materials can improve the separation and transfer efficiency of photogenerated carriers, enhancing photocatalytic performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst with disulfide vacancies for photodegrading chloroquine phosphate and a preparation method thereof. The catalyst has the ability to degrade chloroquine phosphate and has good structural stability and recycling. As long as it is under light conditions, its catalytic activity can be maintained, thereby reducing material consumption and waste generation, and meeting the requirements of sustainable development.

[0006] The specific technical solution for achieving the purpose of the present invention is:

[0007] A method for preparing a double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst comprises the following steps:

[0008] Step 1: Preparation of SV-Bi2S3 solution

[0009] Polyvinyl pyrrolidone and thiourea are dispersed in ethylene glycol (EG) and continuously stirred at 65°C to obtain solution A. Subsequently, 0.1 mol / L bismuth nitrate solution B (bismuth nitrate is also dissolved in ethylene glycol, labeled as solution B) is added dropwise to solution A in an amount equal to 1 / 4 the volume of solution A. After the addition is complete, stirring is continued for 30-60 minutes. After mixing, the mixture is labeled as solution C, which is the SV-Bi2S3 solution. The molar ratio of polyvinyl pyrrolidone, thiourea, and ethylene glycol is 1-8:1-6:2-15.

[0010] The mixed solution C was then transferred to a polytetrafluoroethylene-lined autoclave and maintained at 120-140 °C for 6-10 h. After the reaction, the resulting black precipitate was collected by centrifugation, thoroughly washed with deionized water and ethanol, and then dried in vacuum at 60 °C overnight to obtain SV-Bi2S3.

[0011] Step 2: Preparation of SV-ZnIn2S4

[0012] The SV-ZnIn2S4 powder was synthesized via a one-step hydrothermal method. Specifically, zinc chloride, indium chloride tetrahydrate, and thioacetamide were dissolved in ethylene glycol. The solution was then transferred to a Teflon-lined stainless steel autoclave and maintained at 120-160°C for 10-12 hours. After cooling to room temperature, the solution was washed with ethanol and deionized water to remove any unreacted precursors. The resulting pale yellow SV-ZnIn2S4 powder was vacuum-dried at 60°C. The molar ratio of zinc chloride to indium chloride tetrahydrate to thioacetamide to ethylene glycol was 0.5-1.5:1-2:2-10:5-15.

[0013] Step 3: Preparation of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst

[0014] The SV-ZnIn2S4 prepared in step 2 is weighed and placed in a polytetrafluoroethylene-lined high-pressure reactor, and solution C in step 1 is poured in, stirred for 1-2 h, the reactor is tightened, and heated in an electric constant temperature blast drying oven, the reaction temperature is 120-160 ° C, and the reaction time is 12-18 h; naturally cooled to room temperature, the reactor is opened, and the solid powder is recovered by centrifugal washing at a speed of 8000-10000 rpm and a centrifugal time of 10-20 min. The solid powder is washed with deionized water and ethanol for 3-5 times respectively, and finally placed in a vacuum drying oven at a drying temperature of 60-80 ° C and a drying time of 12-18 h, and ground to obtain the disulfide vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst; wherein the mass volume ratio of the SV-ZnIn2S4 to the solution C is 0.1-0.8 g: 10-30 mL.

[0015] A double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst prepared based on the above method can detect the presence of double sulfur vacancies through EPR spectrometry; scanning electron microscopy shows that the lily-shaped SV-Bi2S3 with double sulfur vacancies and the hydrangea-shaped SV-ZnIn2S4 are tightly combined.

[0016] A disulfide vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst is used to degrade chloroquine phosphate in wastewater. The application process specifically comprises: placing the catalyst in chloroquine phosphate wastewater with a concentration of 5-50 mg / L, adsorbing it in the dark for 30-90 minutes under stirring, and after reaching adsorption equilibrium, turning on a white light LED with a power of 10-80 W for 5-90 minutes. The disulfide vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst generates a large number of free radicals that attack the chloroquine phosphate matrix to promote cracking, and the photodegradation efficiency reaches 72.4-99.3% after 60 minutes of illumination. The mass of the photocatalyst: the volume of the wastewater is 5-200 mg: 5-200 ml.

[0017] The present invention has the following advantages:

[0018] 1) The SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst prepared in the present invention can achieve a maximum degradation efficiency of 99.3% for CQ in 60 min.

[0019] 2) The introduction of sulfur vacancies improves the adsorption and degradation efficiency of CQ on the SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst.

[0020] 3) Compared with the original SV-Bi2S3 and SV-ZnIn2S4, the prepared SV-Bi2S3 / SV-ZnIn2S4 composite photocatalyst can effectively heterogeneous electron / hole recombination, accelerate interfacial electron transfer and thus improve the photocatalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Scanning electron micrographs of SV-Bi2S3, SV-ZnIn2S4 and SV-BZI-50 prepared in Example 3 of the present invention;

[0022] Figure 2 This is a transmission electron micrograph of SV-BZI-50 prepared in Example 3 of the present invention;

[0023] Figure 3 Electron paramagnetic resonance images of sulfur vacancies in SV-Bi2S3, SV-ZnIn2S4, and SV-BZI-50 prepared in Example 3 of the present invention;

[0024] Figure 4 XRD patterns of SV-Bi2S3, SV-ZnIn2S4 and SV-BZI-50 prepared in Example 3 of the present invention;

[0025] Figure 5 FT-IR images of SV-Bi2S3, SV-ZnIn2S4 and SV-BZI-50 prepared in Example 3 of the present invention;

[0026] Figure 6 This is a graph showing the degradation performance of the SV-Bi2S3, SV-ZnIn2S4 and SV-BZI-X series composite photocatalysts of the present invention;

[0027] Figure 7 The cycle performance diagram of SV-BZI-50 prepared in Example 3 of the present invention and the XRD pattern, FT-IR and SEM images before and after five cycle tests;

[0028] Figure 8 The electron paramagnetic resonance images of different types of free radicals are obtained from the capture experiment of SV-BZI-50 prepared in Example 3 of the present invention;

[0029] Figure 9 This is a schematic diagram of the degradation pathway of CQ by SV-BZI-50 prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described with reference to the accompanying drawings. All reagents used in the following examples are conventional reagents of analytical purity and do not require further purification before use; the relevant preparation methods and detection methods are conventional methods. Example

[0031] (1) The synthesis of SV-ZnIn2S4 powder was achieved via a one-step hydrothermal method. Specifically, zinc chloride, indium chloride tetrahydrate, and thioacetamide at a molar ratio of 1:1:2 were dissolved in 20 mL of ethylene glycol. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 160 °C for 12 h. After cooling to room temperature, the solution was washed with ethanol and deionized water to remove any unreacted precursors. After vacuum drying at 60 °C, pale yellow SV-ZnIn2S4 powder was obtained.

[0032] (2) Synthesis of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst

[0033] Polyvinyl pyrrolidone and thiourea were dispersed in ethylene glycol (EG) and stirred continuously at 65°C to obtain solution A. Subsequently, 0.1 mol / L bismuth nitrate solution B (bismuth nitrate was also dissolved in ethylene glycol and marked as solution B) was added dropwise to solution A. The amount of solution B added was 1 / 4 of the volume of solution A. After the addition was completed, stirring was continued for 30 min, and the mixture was marked as solution C. 0.10 g of SV-ZnIn2S4 was weighed and placed in a polytetrafluoroethylene-lined high-pressure reactor in step 1. 30 mL of solution C was poured in and stirred for 1 h. The reactor was tightened and heated in an electric constant temperature blast drying oven. The reaction temperature was 140°C and the reaction time was 12 h. The reactor was naturally cooled to room temperature, the reactor was opened, and the solid powder was recovered by centrifugal washing at a speed of 8000 rpm and a centrifugal time of 10 min. The solid powder was washed 3 times with deionized water and ethanol respectively, and finally placed in a vacuum drying oven at a drying temperature of 60°C and a drying time of 12 h, grinding; the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst was prepared and recorded as SV-BZS-10. Example

[0034] (1) The synthesis of SV-ZnIn2S4 powder was achieved via a one-step hydrothermal method. Specifically, zinc chloride, indium chloride tetrahydrate, and thioacetamide in a molar mass ratio of 1:1:2 were dissolved in 20 m ethylene glycol. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 160°C for 12 h. After cooling to room temperature, the solution was washed with ethanol and deionized water to remove any unreacted precursors. The pale yellow SV-ZnIn2S4 powder was obtained after vacuum drying at 60°C.

[0035] (2) Synthesis of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst

[0036] Polyvinyl pyrrolidone and thiourea were dispersed in ethylene glycol (EG) and stirred continuously at 65°C to obtain solution A. Subsequently, 0.1 mol / L bismuth nitrate solution B (bismuth nitrate was also dissolved in ethylene glycol, marked as solution B) was added dropwise to solution A. The amount of solution B added was 1 / 4 of the volume of solution A. After the addition was completed, stirring was continued for 30 min, and the mixture was marked as solution C. 0.30 g of SV-ZnIn2S4 was weighed and placed in a polytetrafluoroethylene-lined high-pressure reactor in step 1. 30 mL of solution C was poured in and stirred for 1 h. The reactor was tightened and heated in an electric constant temperature blast drying oven. The reaction temperature was 140°C and the reaction time was 12 h. The reactor was naturally cooled to room temperature, the reactor was opened, and the solid powder was recovered by centrifugal washing at a speed of 8000 rpm, centrifugal time 10min, washed with deionized water and ethanol three times respectively, and finally placed in a vacuum drying oven, dried at 60°C, dried for 12h, and ground; the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst was prepared, recorded as SV-BZS-30. Example

[0037] (1) Polyvinyl pyrrolidone and thiourea were dispersed in ethylene glycol (EG) and stirred continuously at 65°C to obtain solution A. Subsequently, 0.1 mol / L bismuth nitrate solution B (bismuth nitrate was also dissolved in ethylene glycol, marked as solution B) was added dropwise to solution A. The amount of solution B added was 1 / 4 of the volume of solution A. After the addition was completed, stirring was continued for 30 min. After mixing, the mixture was marked as solution C. Then, the mixed solution C was transferred to a polytetrafluoroethylene-lined autoclave and maintained at 140°C for 8 h. After the reaction was completed, the black precipitate was collected by centrifugation, thoroughly washed with deionized water and ethanol, and then vacuum dried at 60°C overnight to obtain SV-Bi2S3. The molar ratio of polyvinyl pyrrolidone, thiourea, and EG was 1:1:2.

[0038] (2) The synthesis of SV-ZnIn2S4 powder was achieved via a one-step hydrothermal method. Specifically, zinc chloride, indium chloride tetrahydrate, and thioacetamide in a molar mass ratio of 1:1:2 were dissolved in 20 mL of ethylene glycol. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 160 °C for 12 h. After cooling to room temperature, the solution was washed with ethanol and deionized water to remove any unreacted precursors. After vacuum drying at 60 °C, pale yellow SV-ZnIn2S4 powder was obtained.

[0039] (3) Synthesis of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst

[0040] Weigh 0.50 g of SV-ZnIn2S4 and place it in the polytetrafluoroethylene-lined high-pressure reactor of step 1, pour in 30 mL of solution C of step 1 and stir for 1 h; tighten the reactor and heat it in an electric constant temperature forced air drying oven, the reaction temperature is 140°C, and the reaction time is 12 h; cool naturally to room temperature, open the reactor, and recover the solid powder by centrifugal washing at a speed of 8000 rpm and a centrifugal time of 10 min, wash it with deionized water and ethanol three times respectively, and finally place it in a vacuum drying oven at a drying temperature of 60°C and a drying time of 12 h, and grind it; the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst is obtained, which is recorded as SV-BZS-50 heterojunction photocatalyst. Example

[0041] (1) The synthesis of SV-ZnIn2S4 powder was achieved via a one-step hydrothermal method. Specifically, zinc chloride, indium chloride tetrahydrate, and thioacetamide in a molar mass ratio of 1:1:2 were dissolved in 20 mL of ethylene glycol. The solution was then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 160°C for 12 h. After cooling to room temperature, the solution was washed with ethanol and deionized water to remove any unreacted precursors. The pale yellow SV-ZnIn2S4 powder was obtained after vacuum drying at 60°C.

[0042] (2) Synthesis of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst

[0043] Polyvinyl pyrrolidone and thiourea were dispersed in ethylene glycol (EG) and stirred continuously at 65°C to obtain solution A. Subsequently, bismuth nitrate solution B with a concentration of 0.1 mol / L (bismuth nitrate was also dissolved in ethylene glycol, marked as solution B) was added dropwise to the solution A. The amount of solution B added was 1 / 4 of the volume of solution A. After the addition was completed, stirring was continued for 30 min, and the mixture was marked as solution C. 0.70 g of SV-ZnIn2S4 was weighed and placed in a polytetrafluoroethylene-lined high-pressure reactor in step 1, and 30 mL of solution C in step 1 was poured in and stirred for 1 h. The reactor was tightened and heated in an electric constant temperature blast drying oven at a reaction temperature of 140°C and a reaction time of 12 h. The solid powder was recovered by centrifugal washing at a speed of 8000 rpm and a centrifugal time of 10 min. The solid powder was washed 3 times with deionized water and ethanol respectively, and finally placed in a vacuum drying oven at a drying temperature of 60°C and a drying time of 12 h, grinding; the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst was prepared and recorded as SV-BZS-70. Example

[0044] Weigh 10 mg of the photocatalyst and 15 mg / L CQ solution, respectively, into a 50 ml reaction volume. Stir at 500 rpm in a photocatalytic reactor for 5-60 minutes of dark adsorption. Samples were collected for testing after reaching adsorption equilibrium (CQ's characteristic absorption peak is at 342 nm; adsorption equilibrium is achieved when the absorbance remains constant after two measurements). Then, illuminate with a white LED for 5-60 minutes. Calculate the specific photodegradation efficiency based on the test results.

[0045] To demonstrate the stability of the catalyst's structure and performance, the catalyst was centrifugally washed 3-5 times with water and ethanol, respectively, and recovered by centrifugation. The resulting product was then dried in a vacuum oven at 60°C for 12 hours. In the cyclic experiment, this procedure was repeated five times, resulting in five test cycles. Example

[0046] Capture experiments verified the presence of different photocatalytically active species in SV-BZI-50. 1 mmol / L of capture agents, such as isopropyl alcohol, benzoquinone, silver nitrate, L-histidine, and triethanolamine, were added to a typical photocatalytic reaction solution to capture •OH, •O₂−, e⁻, 1O₂, and h⁺, respectively. Sampling and testing methods were consistent with the original photocatalytic reaction procedure.

[0047] The characteristics of the composite photocatalyst of the present invention can be fully demonstrated by referring to the accompanying drawings of the present invention. Figure 1 The scanning electron microscopy of a shows that pure SV-Bi2S3 is 1 μm lily-shaped, while SV-ZnIn2S4 is 3 μm hydrangea-shaped ( Figure 1 b). After the heterojunction photocatalyst is prepared, the morphology of SV-BZI-50 is a close combination of lily-shaped SV-Bi2S3 and hydrangea-shaped SV-ZnIn2S4 ( Figure 1 c), the size and morphology of the two remain unchanged, and transmission electron microscopy also confirms the successful preparation of the heterojunction catalyst ( Figure 2 ).

[0048] Figure 3 All samples prepared according to Example 3 showed a Lorentzian line with a g value of 2.003, which proves the generation of sulfur vacancies, which not only provide more unsaturated sites for the formation of unpaired electrons but also promote the photoinduced electron / hole separation.

[0049] Figure 4Fourier transform infrared spectroscopy shows that SV-BZS-50 exhibits a spectrum similar to that of SV-Bi2S3. It is worth noting that the stretching vibration at 562 cm-1 is attributed to SV-ZnIn2S4, which indicates that the interaction between SV-BZS-50 and their interface is complex, not just a simple combination.

[0050] Figure 5 X-ray diffraction shows that not only the characteristic peaks of SV-Bi2S3 and SV-ZnIn2S4 can be observed in SV-BZS-50, but also the diffraction peak intensity of SV-ZnIn2S4 in the composite sample increases slightly with the increase of SV-ZnIn2S4 content, which indicates the strong interaction between SV-Bi2S3 and SV-ZnIn2S4 and represents the successful synthesis of heterojunction catalysts.

[0051] Figure 6 The results of CQ photodegradation experiments showed that the CQ degradation efficiency of SV-BZI-50 could reach up to 99.3% within 60 min, which was much higher than that of SV-Bi2S3 and SV-ZnIn2S4. Figure 7 The CQ degradation rate of SV-BZI-50 in a still reached 91.6% after 5 consecutive cycles. The XRD ( Figure 7 b), FT-IR ( Figure 7 c) and SEM( Figure 7 d), demonstrating that the crystal structure, functional groups, and morphology of SV-BZI-50 remain consistent, indicating that it has no catalyst poisoning, is reusable, and has good structural stability.

[0052] The types of reactive oxygen species produced by photocatalytic reactions were detected by capture experiments and electron spin resonance spectroscopy. Figure 8 As shown in Figure 7a, the degradation efficiency without any scavenger was 99.3%, while the addition of AgNO3, BQ, and L-histidine reduced the degradation efficiency to only 28.2%, 21.5%, and 39.7%, respectively. This confirms that the primary active species in the photodegradation of CQ by SV-BZI-50 are e-, .O2-, and •OH. Figures 7b-c show that no characteristic peaks of .O2- and •OH were observed under dark conditions, demonstrating that these species are virtually absent. However, under illumination, characteristic peaks of .O2- and •OH were clearly observed, indicating that more .O2- and •OH species attack CQ under illumination, thereby enhancing the photodegradation efficiency. Furthermore, the reduction of TEMPO by electrons results in the formation of TEMPOH, which decreases the intensity of the electron spin resonance spectrum. Figure 7d shows that under light conditions, the TEMPO signal is significantly reduced, which confirms that the SV-BZI-50 prepared by the constructed heterojunction can generate more electrons and has stronger reduction ability.

[0053] like Figure 9 The initial substrate shown was ionized in positive mass spectrometry mode to yield the corresponding proton adduct quasi-molecular ion [M+H]+ A at m / z 320. Possible reaction pathways are: 1) Cleavage of the Csp2-N bond connecting the quinoline to product B (m / z 159), which may further undergo deamination to produce product D (m / z 142) or de-N-ethylation to produce product Em (m / z 131), which then undergoes further de-N-ethylation to produce product F (m / z 103); 2) Cleavage of the Csp3-N bond to produce aminochloroquinoline (m / z 179) and product D (m / z 142), which then undergoes further deethylation via deethylation to produce product G (m / z 114), which further undergoes deethylation via deethylation to produce product H (m / z 86). Product D (m / z 142) undergoes deethylation via deethaneation to produce product P (m / z 112), which then undergoes oxidative degradation to produce product Q (m / z 112). Furthermore, product D m / z 142 was further oxidized to product I m / z 158, which further degraded by C-C bond cleavage to product m / z 130, followed by deethylation via deethylene to product K m / z 102 or deethylation via deethanization to product P m / z 110. Product I m / z 158 also degraded to product M m / z 130, which further deethylated via deethylene to product N m / z 102 or deethylation via deethanization to product O m / z 100. Based on these oxidative degradation behaviors, it is speculated that the degradation of these products yields small acids, ultimately producing H2O, CO2, CO32-, and NH4+, thereby achieving complete degradation of the compound.

[0054] The above examples demonstrate that the disulfide-vacancy SV-Bi2S3 / SV-Zn2S4 heterojunction photocatalyst prepared by this invention exhibits excellent recyclability and structural stability, enabling efficient treatment of CQ wastewater. Its preparation process is simple and easy to implement, exhibits excellent photocatalytic activity, and demonstrates good operability for large-scale production. This research provides theoretical support for the design of novel heteroatom-deficient heterojunction photocatalysts for the removal of novel water pollutants, contributing to the protection of the ecological environment and the sustainable utilization of water resources.

Claims

1. A method for preparing a double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst, characterized in that: The method comprises the following steps: Step 1: Preparation of SV-Bi2S3 solution Polyvinyl pyrrolidone and thiourea are dispersed in ethylene glycol and continuously stirred at 65°C to obtain solution A. Subsequently, bismuth nitrate solution B having a concentration of 0.1 mol / L is added dropwise to solution A in an amount corresponding to 1 / 4 the volume of solution A. After the addition is completed, stirring is continued for 30-60 minutes. After mixing, the mixture is labeled as solution C, i.e., SV-Bi2S3 solution. The molar ratio of polyvinyl pyrrolidone, thiourea, and ethylene glycol is 1-8:1-6:2-15. Step 2: Preparation of SV-ZnIn2S4 Zinc chloride, indium chloride tetrahydrate, and thioacetamide are dissolved in ethylene glycol, and the solution is then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and maintained at 120-160°C for 10-12 hours. After cooling to room temperature, the solution is washed with ethanol and deionized water to remove any unreacted precursors, and vacuum dried at 60°C to obtain a pale yellow SV-ZnIn2S4 powder. The molar ratio of zinc chloride, indium chloride tetrahydrate, thioacetamide, and ethylene glycol is 0.5-1.5:1-2:2-10:5-15. Step 3: Preparation of SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst Weigh the SV-ZnIn2S4 obtained in step 2 and place it in a polytetrafluoroethylene-lined high-pressure reactor. Pour the solution C obtained in step 1 into the reactor, stir for 1-2 h, tighten the reactor, and heat it in an electric constant-temperature blast drying oven. The reaction temperature is 120-160°C and the reaction time is 12-18 h. Cool the reactor naturally to room temperature, open the reactor, and recover the solid powder by centrifugal washing at a speed of 8000-10000 rpm and a centrifugal time of 10-20 min. Wash the solid powder with deionized water and ethanol for 3-5 times, respectively. Finally, place the solid powder in a vacuum drying oven at a drying temperature of 60-80°C and a drying time of 12-18 h, and grind the solid powder to obtain the disulfide vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst. The mass volume ratio of the SV-ZnIn2S4 to the solution C is 0.1-0.8 g: 10-30 mL.

2. A double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst prepared based on the method described in claim 1.

3. The double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst according to claim 2, characterized in that: The presence of disulfur vacancies can be detected by EPR spectroscopy; scanning electron microscopy shows that the lily-shaped SV-Bi2S3 with disulfur vacancies and the hydrangea-shaped SV-ZnIn2S4 are tightly bound.

4. Use of the disulfide vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst according to claim 2 in degrading chloroquine phosphate in wastewater.

5. The use according to claim 4, characterized in that The specific process includes: placing the catalyst in chloroquine phosphate wastewater with a concentration of 5-50 mg / L, adsorbing in the dark for 30-90 minutes under stirring, and after reaching adsorption equilibrium, turning on a white light LED with a power of 10-80 W for irradiation for 5-90 minutes; the double sulfur vacancy SV-Bi2S3 / SV-ZnIn2S4 heterojunction photocatalyst generates a large number of free radicals to attack the chloroquine phosphate mother body to promote cracking, and the photodegradation efficiency reaches 72.4-99.3% after 60 minutes of illumination; wherein, the mass of the photocatalyst: the volume of wastewater is 5-200 mg: 5-200 ml.

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