S-type heterojunction photocatalyst of FMO (at) F and M-ZIS as well as preparation method and application of S-type heterojunction photocatalyst

Abstract

The invention discloses an S-type heterojunction photocatalyst of FMO (at) F and M-ZIS as well as a preparation method and application of the S-type heterojunction photocatalyst. According to the invention, the S-type heterojunction photocatalyst of Fe and Mo co-doped ZnIn2S4 coated FeMoO4 (FMO (at) F and M-ZIS) can be prepared without using a template agent and a surfactant. The catalyst can take tetracycline hydrochloride as a pollutant (40 ppm), the degradation efficiency of the catalyst can reach 100% under a 10 W LED lamp for 20 min, and the degradation rates of high performance liquid chromatography and three-dimensional fluorescence detection are 100% and 97.4% respectively.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysts, and particularly relates to an S-type heterojunction photocatalyst of FMO@F, M-ZIS, its preparation method and application. Background Technology

[0002] Antibiotics have made significant contributions to the control of bacterial diseases, but their extensive use and discharge have led to increasingly severe water pollution. Tetracycline antibiotics, hailed as a medical miracle due to their broad-spectrum efficacy, have now become a double-edged sword: over 80% of the administered dose is excreted by livestock without being metabolized, seeping into waterways and persisting as a persistent pollutant. These residues fuel the silent spread of antibiotic-resistant bacteria. Among them, tetracycline hydrochloride (TC), due to its low price and significant efficacy, has become one of the most widely used antibiotics in clinical practice, but also one of the most severely abused. In recent years, tetracycline has been consistently detected in rivers, groundwater, and soil, causing serious harm to human health and the ecological environment. However, traditional biological wastewater treatment technologies are ineffective in removing tetracycline, necessitating the development of new and efficient treatment technologies.

[0003] Photocatalysis, as an advanced oxidation technology, can utilize light energy to generate ·OH and ·O2. - The photocatalytic degradation of tetracycline hydrochloride wastewater, along with reactive oxygen species such as ¹O₂, oxidizes and degrades the tetracycline. This technology boasts advantages such as being green and low-carbon, contributing to the development of wastewater treatment towards a synergistic effect of pollution reduction, carbon reduction, and efficiency enhancement, and is expected to become a demonstration technology for tetracycline wastewater treatment. Therefore, research on the efficient photocatalytic degradation of tetracycline hydrochloride wastewater has significant theoretical and academic value for the development of related demonstration technologies.

[0004] In recent years, various semiconductor materials such as metal oxides, perovskites, and graphitic carbon nitride have been widely used in photocatalysis. However, most metal oxides only respond in the ultraviolet light range, resulting in low utilization of sunlight, and are therefore rarely used directly as photocatalytic materials. In contrast, metal sulfides (such as ZnIn2S4) possess visible light responsiveness and strong photogenerated electron reduction capabilities, making them one of the candidate materials for photocatalytic hydrogen production. However, their performance is still limited by the problem of easy recombination of photogenerated carriers. Therefore, researchers have focused on constructing heterojunctions to improve carrier separation efficiency. Among them, S-type heterojunctions have become a current research hotspot due to their well-defined charge transfer pathways and ability to retain strong redox capabilities. This patent utilizes the tunable structure of ZnIn2S4 (ZIS) to construct a heterojunction photocatalyst (FMO@F, M-ZIS) of Fe and Mo co-doped ZnIn2S4 encapsulating FeMoO4 (FMO), aiming to achieve efficient bulk phase separation of photogenerated carriers while maintaining strong redox capabilities for photo-Fenton catalytic degradation of tetracycline hydrochloride. Summary of the Invention

[0005] The purpose of this invention is to provide an S-type heterojunction photocatalyst of FMO@F,M-ZIS, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing an S-type heterojunction photocatalyst of FMO@F,M-ZIS includes the following steps: Synthesis of S1.FMO: Ammonium molybdate was added to ferric nitrate solution, and then the mixture was transferred to an organic solvent for reaction. The product was then washed, dried, and calcined to obtain FMO. S2. FMO, zinc source, indium source and sulfur source are mixed and reacted in an organic solvent, then washed and dried to obtain FMO@F, M-ZIS.

[0007] Furthermore, in step S1, the reaction temperature is 160~200℃ and the reaction time is 0.5~2h.

[0008] Furthermore, in step S1, the mass ratio of ferric nitrate to ammonium molybdate is 10:1.

[0009] Furthermore, in step S1, the calcination conditions are as follows: the temperature is increased to 300~400℃ at a heating rate of 3℃ / min, and then calcined for 0.5~1.5h.

[0010] Furthermore, in step S2, the zinc source is anhydrous zinc chloride, the indium source is indium chloride tetrahydrate, and the sulfur source is thioacetamide.

[0011] Furthermore, in step S2, the molar ratio of zinc source, indium source and sulfur source is 1:2:4, and the molar ratio of FMO mass to zinc source is 21.15-84.6:1.

[0012] Furthermore, in step S2, the reaction temperature is 60~200℃ and the reaction time is 1~12h.

[0013] Furthermore, in step S1, the organic solvent is ethylene glycol, and the washing and drying conditions are: washing with water / ethanol, and vacuum drying at 60~100℃ for 12~24h.

[0014] Furthermore, in step S2, the organic solvent is ethylene glycol, and the washing and drying conditions are: washing with ethanol and vacuum drying at 60~100℃ for 12~24h.

[0015] The above method yields an FMO@F, M-ZIS heterojunction photocatalyst. Furthermore, the FMO@F, M-ZIS heterojunction photocatalyst exhibits both high bulk photogenerated carrier separation efficiency and strong reducing and oxidizing capabilities.

[0016] The above-mentioned FMO@F, M-ZIS heterojunction photocatalyst is used in the photocatalytic degradation of pollutants.

[0017] The XFMO@F,M-ZIS S-type heterojunction photocatalyst prepared in this invention, where XFMO@F,M-ZIS represents the theoretical molar mass percentage of FMO in ZIS, F,M-ZIS indicates the incorporation of ZIS crystal structure, and @ indicates that FMO is encapsulated by F,M-ZIS. This invention can prepare an S-type heterojunction photocatalyst of Fe and Mo co-doped ZIS-encapsulated FMO without the use of template agents or surfactants. This catalyst can achieve a 100% degradation efficiency of tetracycline hydrochloride (40 ppm) under a 10W LED lamp for 20 min, with degradation rates of 100% and 97.4% as determined by high-performance liquid chromatography and three-dimensional fluorescence detection, respectively. Currently, no method for preparing and applying an FMO@F,M-ZIS S-type heterojunction photocatalyst has been reported.

[0018] Mechanism: This invention prepares FMO photocatalysts via a one-step hydrothermal method. Guided by ion exchange theory, Fe and Mo are further introduced into the ZIS structure via a solvothermal method, and FMO is further encapsulated to obtain an S-type heterojunction photocatalyst of FMO@F, M-ZIS. Secondly, theoretical calculations show that the work functions of FMO and ZIS are significantly different, and the S-type heterojunction charge transport mechanism is achieved through the close contact between their heterojunction interfaces. Simultaneously, Fenton catalytic elements are introduced at both the oxidation and reduction ends to synergistically enhance the Fenton reaction. Finally, the construction of the S-type heterojunction achieves bulk phase separation of photogenerated carriers while retaining strong reducing and oxidizing capabilities. Furthermore, the introduction of FMO in this invention inhibits ZIS aggregation, increases the specific surface area, exposes more active sites, and enhances photocatalytic activity. The preparation method of the FMO@F, M-ZIS S-type heterojunction photocatalyst described in this invention is simple, uses abundant raw materials, exhibits excellent photocatalytic performance, and has significant economic and social benefits. It also provides important insights for the development of sustainable chemical synthesis.

[0019] The advantages of this invention are: 1. This invention uses ethylene glycol as a reactant to prepare FMO@F, M-ZIS S-type heterojunction photocatalysts. The preparation conditions are mild, the equipment requirements are low, no additional surfactants or templates are required, the raw material cost is low and the atom utilization rate is high, and it is easy to realize industrial-scale production. 2. Ethylene glycol has high viscosity, which can effectively inhibit FMO deposition and make it easier to form uniform FMO@F, M-ZIS S-type heterojunction photocatalysts, significantly increasing the specific surface area of ​​the catalyst and exposing more active iron sites and photoresponse sites; 3. The reducing environment provided by ethylene glycol is favorable for Fe. 2+ and Mo5+ The stable existence of [a specific substance] and its successful doping into ZIS further promoted the [a specific process] of Mo under photoexcitation conditions. 5+ Xiang Mo 4+ The conversion of Fe accelerates the Fenton reaction. 3+ To Fe 2+ The cycle is cyclical, and the hydrolysis and precipitation of iron ions are suppressed. Simultaneously, the Fe at the oxidation and reduction ends... 2+ The efficiency of the photo-Fenton reaction can be enhanced through the synergistic effect of two sites. In addition, the construction of the S-type heterojunction not only achieves efficient separation of photogenerated carriers, but also retains the strong oxidation and reduction capabilities of the material, ultimately significantly improving the photocatalytic activity of the catalyst. 4. Based on reasonable theoretical design, the heterojunction photocatalyst prepared by the present invention using ethylene glycol as a reactant exhibits excellent pollutant degradation activity in the photo-Fenton system, with a wide range of applications and good recyclability. Attached Figure Description

[0020] Figure 1 Photocatalyst structure characterization diagram. Among them: (a) XRD, (b) N2 adsorption-desorption curve, (c) pore size distribution, (d) Raman spectrum, (e) FTIR, (f) XPS full spectrum, (g) XPS fine spectrum of Fe, (h) XPS fine spectrum of Mo, (i) CP-OES.

[0021] Figure 2 Morphological characterization of the photocatalysts. (a) SEM images of FMO, (b) ZIS and (c) 10-FMO@F, M-ZIS; (d) TEM image of 10-FMO@F, M-ZIS; (e) HRTEM image of 10-FMO@F, M-ZIS and (f) corresponding lattice fringes; (g) SAED image of 10-FMO@F, M-ZIS; (g1-g6) Mapping images of different elements in 10-FMO@F, M-ZIS.

[0022] Figure 3 Photocatalytic degradation activity. Concentration versus time curves at different times: (a) photodegradation and (b) photocatalytic degradation; three-dimensional fluorescence spectroscopy: (c) 40 ppm tetracycline hydrochloride and (d) after 20 min photo-Fenton degradation; high performance liquid chromatography: (e) 40 ppm tetracycline hydrochloride and (d) after 20 min photo-Fenton degradation. Detailed Implementation

[0023] Example 1 A method for preparing an S-type heterojunction photocatalyst of FMO@F,M-ZIS includes the following steps: (1) Add 2 mmol Fe(NO3)3 to 2 ml of water, then add 0.3 mmol of ammonium molybdate to dissolve the above solution. Add the solution to 36 ml of ethylene glycol, sonicate and stir until completely dissolved. Transfer to a 100 ml reactor, react at 190 °C for 1 h, cool to room temperature, wash three times with water / ethanol, and dry under vacuum at 80 °C for 12 h. Calcine the obtained product at 3 °C / min to 350 °C for 1 h to obtain FMO; (2) The FMO (21.15 mg, 42.3 mg and 84.6 mg) obtained above were added to 20 ml of ethylene glycol and ultrasonically dispersed. 1 mmol ZnCl2, 2 mmol InCl3 and 4 mmol TAA were added respectively, and the mixture was ultrasonically stirred for 10 min. The mixture was placed in a 50 mmol polytetrafluoroethylene reactor and heated at 80 °C for 2 h. The mixture was washed with ethanol and vacuum dried at 80 °C for 12 h to obtain XFMO@F, M-ZIS S-type heterojunction photocatalyst, where X is 5, 10 or 20.

[0024] Test conditions: Photocatalytic degradation of pollutants: Using 40 ppm tetracycline hydrochloride as the pollutant: 3 mg of catalyst was added to 15 mL of tetracycline hydrochloride solution, and the mixture was darkly adsorbed for 20 min. Under the excitation of a 10 W LED lamp, a sample was taken every 20 min, filtered through a 0.22 μm filter membrane, and the absorbance of the filtrate was measured.

[0025] Photo-Fenton degradation of pollutants: Using 40 ppm tetracycline hydrochloride as the pollutant: A certain amount of catalyst was added to 15 mL of tetracycline hydrochloride solution, and the mixture was allowed to adsorb in the dark for 20 min. Then, 15 µL of H2O2 was added, and a sample was taken at a certain time under the excitation of a 10 W LED lamp. The sample was then filtered through a 0.22 μm filter membrane, and the absorbance of the filtrate was measured.

[0026] Comparative Example 1 ZnCl2, InCl3, and TAA were dispersed in 20 mL of ethylene glycol at a molar ratio of 1:2:4. The mixture was stirred for 30 min and then transferred to a 50 mL polytetrafluoroethylene high-pressure reactor. The reactor was kept at 80 °C for 2 h and then allowed to cool naturally to room temperature. The resulting product was washed with anhydrous ethanol by centrifugation and dried under vacuum to obtain ZnIn2S4, which was named ZIS.

[0027] Comparative Example 2 2 mmol Fe(NO3)3 was added to 2 ml of water, followed by 0.3 mmol of ammonium molybdate. The solution was dissolved and then added to 36 ml of ethylene glycol. The solution was sonicated and stirred until completely dissolved. The solution was transferred to a 100 ml reactor and incubated at 190 °C for 1 h. After cooling to room temperature, the product was washed three times with water / ethanol and dried under vacuum at 80 °C for 12 h. The resulting product was calcined in air at 350 °C for 1 h at a rate of 3 ppm to obtain FeMoO4, which was named FMO.

[0028] Comparative Example 3 21.15 mg of FMO was added to 20 mL of ethylene glycol solvent and sonicated for 10 min. Then, 1 mmol of ZnCl2, 2 mmol of InCl3·4H2O and 4 mmol of TAA were added sequentially, stirred for 30 min and transferred to a 50 mL polytetrafluoroethylene reactor and kept at 80 °C for 2 h. After washing three times with anhydrous ethanol and vacuum drying at 80 °C, ZIS loaded with and intercalated with FMO was obtained and named 5-FMO@F, M-ZIS.

[0029] Comparative Example 4 42.3 mg of FMO was added to 20 mL of ethylene glycol solvent and sonicated for 10 min. Then, 1 mmol ZnCl2, 2 mmol InCl3·4H2O and 4 mmol TAA were added sequentially, stirred for 30 min and transferred to a 50 mL polytetrafluoroethylene reactor and kept at 80 °C for 2 h. After washing three times with anhydrous ethanol and vacuum drying at 80 °C, ZIS loaded with and intercalated with FMO was obtained and named 10-FMO@F, M-ZIS.

[0030] Comparative Example 5 84.6 mg of FMO was added to 20 mL of ethylene glycol solvent and sonicated for 10 min. Then, 1 mmol of ZnCl2, 2 mmol of InCl3·4H2O and 4 mmol of TAA were added sequentially, stirred for 30 min and transferred to a 50 mL polytetrafluoroethylene reactor. The mixture was kept at 120 °C for 2 h, washed three times with anhydrous ethanol and dried under vacuum at 80 °C to obtain ZIS loaded with FMO, named 20-FMO@F, M-ZIS.

[0031] Comparative Example 6 Add 100 mg of 10FMO / ZIS to 20 ml of 1 M HCl, stir for 6 h, wash three times with anhydrous ethanol, and dry under vacuum at 80 °C to obtain F, M-ZIS.

[0032] Comparative Example 7 42.3 mg of FMO was added to 20 mL of ethylene glycol solvent, sonicated for 10 min, then 423 mg of ZIS was added, stirred for 2 hours, washed three times with anhydrous ethanol, and vacuum dried at 80 °C to obtain 10-FMO / F, M-ZIS.

[0033] result: Figure 1 The structure of the composite material prepared in this invention is characterized. Figure 1 The results show that both FMO and ZIS correspond to the standard card. However, with the addition of FMO, its diffraction peaks are not obvious in the composite material, which is due to its reduced strength and lower proportion. The characteristic peaks of FMO become visible when its proportion increases to 20%. Figure 1 b and c indicate that the specific surface area of ​​10-FMO@F, M-ZIS is significantly increased (70 m²). 2 ( / g) and the average pore size is significantly increased, which is more conducive to mass transfer and improves the active sites. Figure 1 As shown in d and e, the composite material surface lacks Mo-S bonds, while the interface contains Mo-S bonds, which is more conducive to the separation of photogenerated charges. This is further confirmed by XPS (…). Figure 1 fh) confirms that Fe 2+ and Mo 5+ Successfully incorporated into the ZIS crystal structure, and further confirmed by IXP-OES, it substituted Zn. 2+ The site. In summary, we successfully prepared 10-FMO@F, M-ZIS. Furthermore, Figure 2 The microstructure of the photocatalyst in this invention was characterized by SEM and TEM. FMO exhibited a spherical structure. Figure 2 a), and in the introduction of the ZIS system, the sheet-like structure of ZIS ( Figure 2 b) Encapsulated on the surface of FMO, the composite material exhibits a nanosheet-encapsulated spherical structure. Figure 2 c). HRTEM confirmed that the interplanar spacing was 0.33 nm ( Figure 2 e and f), which correspond to the 110 crystal plane of ZIS, a result further confirmed by electron diffraction, and the 220 crystal plane of FMO also exists ( Figure 2 g). The elemental mapping diagram confirms the uniform distribution of elements in the FMO@F, M-ZIS S-type heterojunction photocatalyst. Figure 2 g1-g6). Figure 3 The degradation activity of the obtained photocatalysts was evaluated. Among them, 10FMO@F and M-ZIS showed the best photocatalytic degradation activity and photo-Fenton activity. Figure 3 (a and b), and in photo-Fenton degradation, the degradation rate of tetracycline hydrochloride can reach 100% within 20 minutes. High performance liquid chromatography and three-dimensional fluorescence also confirmed that its overall degradation rate was 100% and 97.4%, respectively. Figure 3c-f)。

Claims

1. A method for preparing an S-type heterojunction photocatalyst of FMO@F,M-ZIS, characterized in that, Includes the following steps: Synthesis of S1.FMO: Ammonium molybdate was added to ferric nitrate solution, and then the mixture was transferred to an organic solvent for reaction. The product was then washed, dried, and calcined to obtain FMO. S2. FMO, zinc source, indium source and sulfur source are mixed and reacted in an organic solvent, then washed and dried to obtain FMO@F, M-ZIS.

2. The preparation method according to claim 1, characterized in that: In step S1, the reaction temperature is 160~200℃ and the reaction time is 0.5~2h.

3. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of ferric nitrate to ammonium molybdate is 10:

1.

4. The preparation method according to claim 1, characterized in that: In step S1, the calcination conditions are as follows: the temperature is increased to 300~400℃ at a heating rate of 3℃ / min, and then calcined for 0.5~1.5h.

5. The preparation method according to claim 1, characterized in that: In step S2, the zinc source is anhydrous zinc chloride, the indium source is indium chloride tetrahydrate, and the sulfur source is thioacetamide.

6. The preparation method according to claim 1, characterized in that: In step S2, the molar ratio of zinc source, indium source and sulfur source is 1:2:4, and the molar ratio of FMO mass to zinc source is 21.15-84.6:

1.

7. The preparation method according to claim 1, characterized in that: In step S2, the reaction temperature is 60~200℃ and the reaction time is 1~12h.

8. The preparation method according to claim 1, characterized in that: The organic solvent used in steps S1 and S2 is ethylene glycol, and the washing and drying conditions are: washing with water / ethanol and vacuum drying at 60~100℃ for 12~24h.

9. The S-type heterojunction photocatalyst of FMO@F,M-ZIS prepared by the preparation method according to any one of claims 1-8.

10. The application of the photocatalyst as described in claim 9 in photo-Fenton catalysis.

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