Preparation and photocatalytic application of double-s heterojunction ZIF-67@NiCo-LDH@Ag2S nanobox

Abstract

The application discloses a preparation and photocatalytic application of a double S-type heterojunction ZIF-67@NiCo-LDH@Ag2S (H-Z@NC@Ag2S) nanobox. The application provides a preparation method of the double S-type heterojunction H-Z@NC@Ag2S nanobox material. The prepared H-Z@NC@Ag2S has a unique structure. Hollow ZIF-67-C dodecahedron provides a dodecahedron framework for H-ZIF-67-C@NiCo-LDH nanosheet, inhibits accumulation of the H-ZIF-67-C@NiCo-LDH nanosheet, enriches photocatalytic active sites, increases a specific surface area, and improves a light absorption range and intensity. Meanwhile, the Ag2S nanoparticles have excellent optical performance. Under visible light irradiation, the Ag2S nanoparticles continuously absorb light energy inside, and effectively prevent light loss in a reaction system. Therefore, the hollow layered H-Z@NC@Ag2S composite catalyst has excellent stability and photocatalytic capacity, can photocatalytically degrade norfloxacin antibiotics, and still has a high photocatalytic efficiency after 6 cycles.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic water purification technology, and particularly to the preparation of double S-type heterojunction ZIF-67@NiCo-LDH@Ag2S nanoboxes and their application in the photocatalytic degradation of norfloxacin. Background Technology

[0002] The use of antibiotics in medicine and breeding presents a dual challenge to human health and the environment. While these drugs are widely used in treating bacterial infections, long-term use leads to their accumulation in food and the environment. Norfloxacin (NOR), a representative antibiotic, is an amphiphilic molecule that can exist stably in different ionic forms in acidic or alkaline environments. Common techniques for removing these antibiotics include biodegradation, adsorption, Fenton treatment, membrane separation, ozonation, and photocatalysis. However, due to the high stability and resistance to biotherapy of antibiotics, traditional methods struggle to completely remove these residues. Therefore, adsorption-photocatalysis has emerged as a promising approach. This technology combines the advantages of adsorption and photocatalysis, offering simple operation and no secondary pollution. However, achieving efficient purification requires the development of highly active, interference-resistant, and stable visible light-driven photocatalysts. Therefore, this invention must comprehensively consider technical, economic, and environmental risks to find novel photocatalysts for efficient and sustainable environmental remediation.

[0003] Compared to traditional modification strategies, constructing double-S heterojunctions can continuously improve photocatalytic performance. These double-S heterojunctions maintain high redox performance of photogenerated charges and enhance interfacial electron transfer capabilities, thereby improving photocatalytic activity. The design of double-S heterojunction materials involves adjusting the internal electric field (IEF), which places specific requirements on the energy difference between semiconductors. The unique two-dimensional structure of layered bimetallic hydroxides (LDHs) is conducive to efficient electron transfer and chemical exchange between photocatalysts. However, the stacking of two-dimensional layers often masks many active metal sites, posing a challenge to photocatalysis. Therefore, suitable synthetic strategies must be designed to develop novel, highly efficient photocatalysts based on LDHs. Metal-organic frameworks (MOFs) are promising photocatalytic materials due to their unique structure and corresponding catalytic properties. Among them, ZIF-67 is a promising photocatalyst due to its excellent stability, durability, and photoresponsiveness in aqueous solutions, strongly alkaline environments, and high-temperature environments. Furthermore, the cage-like structure of ZIF-67 facilitates composites with other semiconductor materials, allowing for the design of hollow and core-shell structures with energy level structures tuned to satisfy ·OH and ·O2. -The formation of LDH photocatalysts is possible, but the high carrier recombination rate of pure ZIF-67 limits its widespread application. A notable research direction is the use of MOFs as self-sacrificing templates to prepare LDH photocatalysts. The uniformly distributed metal centers in MOFs provide a reasonable basis for the dispersion of metal sources. By utilizing these dispersed metal sources in situ, the structure of LDH can be obtained, thus avoiding self-packaging. Therefore, the preparation of LDH / MOF hybrid photocatalysts through precise and controllable partial epitaxial transformation of MOF templates can combine MOFs and LDHs with bimetallic centers, fully leveraging the advantages of both to achieve a "whole greater than the sum of its parts" effect. The preparation of hierarchical Ni-Co-MOF / LDH photocatalysts by combining Ni-Co-LDHs with Ni-Co-MOFs can fully utilize the advantages of both, achieving a balance between performance and stability, resulting in a "1+1>2" effect. However, the synthesized binary photocatalysts can only absorb a small range of the solar spectrum, which greatly limits the utilization efficiency of solar energy. Summary of the Invention

[0004] To address the problems of existing technologies, this invention utilizes the synergistic effect of a multispectral system to construct a ternary heterojunction, resulting in a system with a longer photocarrier lifetime and a suitable bandgap position, effectively isolating photocarriers and expanding the light absorption range. Therefore, to overcome this drawback, a third component is chosen to broaden the light absorption range of the composite material. Ag2S has a narrow bandgap of approximately 1.0 eV, which can effectively collect visible and near-infrared light, enhancing the photocatalytic activity in these two regions and achieving a full-spectrum response of the photocatalytic system. Furthermore, Ag2S exhibits strong localized surface plasmon resonance (LSPR) absorption throughout the visible and near-infrared regions. Therefore, this invention rationally designs a double-S-type heterojunction ZIF-67@NiCo-LDH@Ag2S nanobox composite photocatalyst (HZ@NC@Ag2S), that is, using MOF as a self-sacrificing template to prepare a high-efficiency multi-level nanobox photocatalyst for in-situ deposition of silver sulfide in LDH bimetallic organic framework material, and successfully applied it to multiple photocatalytic degradations of norfloxacin.

[0005] This invention first provides a method for preparing a double S-type heterojunction HZ@NC@Ag2S nanobox, the preparation process of which is as follows: Figure 1 As shown, the specific steps include: Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 ℃ at a heating rate of 5 ℃ / min, and annealed at 450 ℃ for 4 h. Then it was cooled to room temperature to obtain purple calcined ZIF-67.

[0006] Step 2: Calcined ZIF-67 and nickel nitrate hexahydrate were dissolved in 85 mL of ethanol and sonicated for 30 min to disperse and mix evenly. The mixture was then transferred to a 100 mL PTFE-lined stainless steel autoclave and heated to 120 °C at a rate of 5 °C / min, and held at 120 °C for 2 hours to obtain a core-shell structured ZIF-67-C@NiCo-LDH. To further obtain a hollow core-shell structured H-ZIF-67-C@NiCo-LDH with a larger specific surface area, 100 mg of ZIF-67-C@NiCo-LDH was placed in 80 mL of an ethanol-water solution (ethanol to water volume ratio of 8:3) and sonicated for 30 min. The mixture was then transferred to a 250 mL three-necked flask and refluxed with stirring for 1 hour. After reflux, the product was washed three times each with ethanol and pure water, vacuum filtered, and then dried in a vacuum oven at 60 °C for 12 hours to obtain the product H-ZIF-67-C@NiCo-LDH.

[0007] Step 3: Using ultrasound treatment, 100 mg of H-ZIF-67-C@NiCo-LDH was dispersed in 80 mL of ethanol. Then, silver nitrate and thioacetamide were dissolved in 50 mL of ethanol. After ultrasound treatment for half an hour, the ethanol solution of silver nitrate and thioacetamide was added to the former H-ZIF-67-C@NiCo-LDH dispersion, and ultrasound treatment was continued for 5 minutes to mix thoroughly. The mixture was then stirred and refluxed for 1 hour, followed by vacuum filtration and collection. The mixture was washed three times with ethanol and finally dried in a vacuum oven at 60°C for 12 hours to obtain the final sample, HZ@NC@Ag2S.

[0008] In the preparation method of the aforementioned double S-type heterojunction HZ@NC@Ag2S nanobox, the preparation method of the rhombic dodecahedron ZIF-67 is as follows: Co(NO3)2·6H2O (0.1455 g) solution and dimethylimidazole (0.1640 g) solution are prepared separately using 5 mL of methanol solution. The dimethylimidazole solution is poured into the Co(NO3)2·6H2O solution and stirred at high speed to ensure thorough mixing of the two solutions. The mixture is stirred at room temperature for 30 minutes, then allowed to stand for 24 hours. After the reaction is complete, the sample is washed with methanol and deionized water, respectively. The washed sample is then vacuum dried in a 60°C oven for 12 hours, yielding a purple powder, which is the rhombic dodecahedron ZIF-67.

[0009] In the preparation method of the above-mentioned double S-type heterojunction HZ@NC@Ag2S nanobox, the total mass of the calcined ZIF-67 and nickel nitrate hexahydrate in step 2 is 200 mg, and the mass ratio is 1:1~3:1.

[0010] In the preparation method of the above-mentioned double S-type heterojunction HZ@NC@Ag2S nanobox, the mass ratio of silver nitrate and thioacetamide in step 3 is 1:0.5~1.

[0011] In the above-mentioned method for preparing the double S-type heterojunction HZ@NC@Ag2S nanobox, in the silver nitrate and thioacetamide ethanol solution described in step 3, the total mass ratio of silver nitrate and thioacetamide to the volume ratio of ethanol is 1:1 to 3.5.

[0012] The HZ@NC@Ag2S nanobox composite catalyst prepared in this invention has a hollow, layered structure, such as... Figure 2 and Figure 3 As shown, it can be used for the adsorption-photocatalytic degradation of norfloxacin.

[0013] The HZ@NC@Ag2S nanobox composite catalyst prepared in this invention is characterized by: an adsorption rate of norfloxacin greater than 10% under dark conditions, a photodegradation rate greater than 90% under visible light irradiation, a mineralization degree greater than 80%, and a degradation rate constant of 0.035~0.040 min. -1 .

[0014] In summary, the beneficial effects of this invention are reflected in: This invention prepares LDH / MOF hybrid photocatalysts through precise and controllable partial epitaxial conversion of MOF templates, giving full play to the advantages of both and achieving the effect of "the whole being greater than the sum of its parts".

[0015] This invention significantly enhances the photocatalytic effect by autonomously assembling a narrow-bandgap silver sulfide and a multifunctional LDH bimetallic organic framework composite photocatalyst based on ZIF-67 into a double S-type heterojunction structure HZ@NC@Ag2S composite catalyst.

[0016] The hollow, layered HZ@NC@Ag2S double S-type heterojunction structure prepared in this invention has a unique structure. The hollow ZIF-67-C rhombic dodecahedron provides a rhombic dodecahedral framework for the derived H-ZIF-67-C@NiCo-LDH nanosheets, inhibiting the accumulation of H-ZIF-67-C@NiCo-LDH nanosheets, enriching photocatalytic active sites, increasing specific surface area, and improving its light absorption range and intensity. Simultaneously, due to the excellent optical properties of Ag2S nanoparticles, they continuously absorb light energy inside under visible light irradiation, effectively preventing light loss in the reaction system. Therefore, the HZ@NC@Ag2S composite catalyst exhibits excellent stability and photocatalytic ability, capable of photocatalytically degrading norfloxacin antibiotics, and maintaining high photocatalytic efficiency even after multiple cycles. Attached Figure Description

[0017] Figure 1 The preparation process of the HZ@NC@Ag2S composite photocatalyst prepared in Examples 1-3 of this invention.

[0018] Figure 2 Scanning electron microscope image of the hollow layered structure of the HZ@NC@Ag2S double S-type heterojunction.

[0019] Figure 3 Transmission electron microscope image of the hollow layered structure of the HZ@NC@Ag2S double S-type heterojunction.

[0020] Figure 4 The photodegradation performance of the HZ@NC@Ag2S composite photocatalysts prepared in Examples 1-3 of this invention.

[0021] Figure 5 Cyclic performance of the HZ@NC@Ag2S composite photocatalysts prepared in Examples 1-3 of this invention. Detailed Implementation

[0022] The present invention will be further described below through specific embodiments, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or variations based on the basic idea of ​​the present invention, as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0023] The specific procedures for the adsorption and photocatalysis experiments involved in this invention are as follows: A solution containing norfloxacin is fed into a 200 mL jacketed glass reaction vessel to supply the photocatalytic system for reaction. The temperature is controlled by a thermostatic circulator (cooler). A cylindrical high-pressure xenon long-arc lamp (h=500 mm, Φ=50 mm, GXH300W, Beijing Prince Technology Co., Ltd.) is installed around the reaction jacket of the photocatalytic glass instrument as a radiation source and equipped with a synthetic quartz window. The quartz window allows illumination of the photocatalyst surface, and a 300 W xenon light source is located in the center of the quartz window. The xenon lamp intensity is calibrated using a thermal power meter. The photodegradation solution is collected using a syringe. The lamp is placed in a double-layered quartz water-cooled jacket, maintaining the temperature at 298 K. Approximately 0.02 g of photocatalyst material is added to a 20 mg / L norfloxacin solution. At the start of the reaction, the suspension is allowed to adsorb in the dark for 60 minutes to establish adsorption / desorption equilibrium. Samples were drawn at 5-minute intervals and filtered using a syringe organic filter (pore size: 0.45 µm). The filtrate was collected and further analyzed by chromatography. The density of the pure water used in all experiments of this invention was 1000 kg / m³. 3 .

[0024] Comparison Case 1 The preparation method of rhombic dodecahedron ZIF-67 is as follows: Co(NO3)2·6H2O (0.1455 g) solution and dimethylimidazole (0.1640 g) solution were prepared separately using 5 mL of methanol solution. The dimethylimidazole solution was poured into the Co(NO3)2·6H2O solution and stirred at high speed to ensure thorough mixing of the two solutions. The mixture was stirred at room temperature for 30 minutes, then allowed to stand for 24 hours. After the reaction was complete, the sample was washed with methanol and deionized water, respectively. The washed sample was then vacuum dried in a 60°C oven for 12 hours, yielding a purple powder, which was rhombic dodecahedron ZIF-67. The obtained rhombic dodecahedral ZIF-67 catalyst showed an adsorption rate of 19.435% for norfloxacin under dark conditions, and a photodegradation rate of 44.941% under visible light irradiation, with a mineralization degree of 35.069% and a degradation rate constant of 0.00955 min⁻¹. -1 .

[0025] Comparison Case 2 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min, and annealed at 450 °C for 4 hours. Then it was cooled to room temperature to obtain a purplish-black calcined ZIF-67 sample. The obtained ZIF-67-C catalyst showed an adsorption rate of 17.69% for norfloxacin under dark conditions, and a photodegradation rate of 52.988% under visible light irradiation, with a mineralization degree of 34.213% and a degradation rate constant of 0.012 min. -1 .

[0026] Comparison Case 3 Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min. The sample was annealed at 450 °C for 4 hours and then cooled to room temperature to obtain purple calcined ZIF-67.

[0027] Step 2: Dissolve 50 mg of calcined ZIF-67 and 150 mg of nickel nitrate hexahydrate in 85 mL of ethanol, sonicate for 30 min to disperse and mix evenly, then transfer the mixture to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heat to 120 °C at a heating rate of 5 °C / min, and hold at 120 °C for 2 hours to obtain the core-shell structured ZIF-67-C@NiCo-LDH.

[0028] The obtained ZIF-67-C@NiCo-LDH catalyst showed an adsorption rate of 16.065% for norfloxacin under dark conditions, and a photodegradation rate of 87.793% under visible light irradiation, with a mineralization degree of 67.354% and a degradation rate constant of 0.03489 min. -1 .

[0029] Comparison Case 4 Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min. The sample was annealed at 450 °C for 4 hours and then cooled to room temperature to obtain purple calcined ZIF-67.

[0030] Step 2: Dissolve 50 mg of calcined ZIF-67 and 150 mg of nickel nitrate hexahydrate in 85 mL of ethanol. Sonicate the solution for 30 min to disperse and mix it thoroughly. Then, transfer the mixture to a 100 mL PTFE-lined stainless steel autoclave and heat it to 120 °C at a rate of 5 °C / min. Hold the temperature at 120 °C for 2 hours to obtain a core-shell structured ZIF-67-C@NiCo-LDH. To further obtain a hollow core-shell structured H-ZIF-67-C@NiCo-LDH with a larger specific surface area, place 100 mg of ZIF-67-C@NiCo-LDH in 80 mL of an ethanol-water solution (ethanol to water volume ratio of 8:3) and sonicate for 30 min. Then, transfer the mixture to a 250 mL three-necked flask and reflux it with stirring for 1 hour. After reflux, the product was washed three times each with ethanol and pure water, vacuum filtered, and then dried in a vacuum oven at 60 °C for 12 hours to obtain the product H-ZIF-67-C@NiCo-LDH.

[0031] The obtained H-ZIF-67-C@NiCo-LDH catalyst showed an adsorption rate of 12.22% for norfloxacin under dark conditions, and a photodegradation rate of 77.773% under visible light irradiation, with a mineralization degree of 69.206% and a degradation rate constant of 0.0237 min⁻¹. -1 .

[0032] Implementation Case 1 Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min. The sample was annealed at 450 °C for 4 hours and then cooled to room temperature to obtain purple calcined ZIF-67.

[0033] Step 2: Dissolve 50 mg of calcined ZIF-67 and 150 mg of nickel nitrate hexahydrate in 85 mL of ethanol. Sonicate the solution for 30 min to disperse and mix it thoroughly. Then, transfer the mixture to a 100 mL PTFE-lined stainless steel autoclave and heat it to 120 °C at a rate of 5 °C / min. Hold the temperature at 120 °C for 2 hours to obtain a core-shell structured ZIF-67-C@NiCo-LDH. To further obtain a hollow core-shell structured H-ZIF-67-C@NiCo-LDH with a larger specific surface area, place 100 mg of ZIF-67-C@NiCo-LDH in 80 mL of an ethanol-water solution (ethanol to water volume ratio of 8:3) and sonicate for 30 min. Then, transfer the mixture to a 250 mL three-necked flask and reflux it with stirring for 1 hour. After reflux, the product was washed three times each with ethanol and pure water, vacuum filtered, and then dried in a vacuum oven at 60 °C for 12 hours to obtain the product H-ZIF-67-C@NiCo-LDH.

[0034] Step 3: Using ultrasound treatment, 100 mg of H-ZIF-67-C@NiCo-LDH was dispersed in 80 mL of ethanol. Then, 10 mg of silver nitrate and 5.63 mg of thioacetamide were dissolved in 50 mL of ethanol. After ultrasound treatment for half an hour, the ethanol solution of silver nitrate and thioacetamide was added to the former H-ZIF-67-C@NiCo-LDH dispersion, and ultrasound treatment was continued for 5 minutes to mix thoroughly. The mixture was then stirred and refluxed for 1 hour, followed by vacuum filtration and collection. The sample was washed three times with ethanol and finally dried in a vacuum oven at 60°C for 12 hours to obtain the final sample HZ@NC@Ag2S-1.

[0035] The obtained HZ@NC@Ag2S-1 nanobox composite catalyst showed an adsorption rate of 13.925% for norfloxacin under dark conditions, and a photodegradation rate of 91.068% under visible light irradiation, with a mineralization degree of 80.03% and a degradation rate constant of 0.03509 min. -1 .

[0036] Implementation Case 2 Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min. The sample was annealed at 450 °C for 4 hours and then cooled to room temperature to obtain purple calcined ZIF-67.

[0037] Step 2: Dissolve 50 mg of calcined ZIF-67 and 150 mg of nickel nitrate hexahydrate in 85 mL of ethanol. Sonicate the solution for 30 min to disperse and mix it thoroughly. Then, transfer the mixture to a 100 mL PTFE-lined stainless steel autoclave and heat it to 120 °C at a rate of 5 °C / min. Hold the temperature at 120 °C for 2 hours to obtain a core-shell structured ZIF-67-C@NiCo-LDH. To further obtain a hollow core-shell structured H-ZIF-67-C@NiCo-LDH with a larger specific surface area, place 100 mg of ZIF-67-C@NiCo-LDH in 80 mL of an ethanol-water solution (ethanol to water volume ratio of 8:3) and sonicate for 30 min. Then, transfer the mixture to a 250 mL three-necked flask and reflux it with stirring for 1 hour. After reflux, the product was washed three times each with ethanol and pure water, vacuum filtered, and then dried in a vacuum oven at 60 °C for 12 hours to obtain the product H-ZIF-67-C@NiCo-LDH.

[0038] Step 3: Using ultrasound treatment, 100 mg of H-ZIF-67-C@NiCo-LDH was dispersed in 80 mL of ethanol. Then, 20 mg of silver nitrate and 11.26 mg of thioacetamide were dissolved in 50 mL of ethanol. After ultrasound treatment for half an hour, the ethanol solution of silver nitrate and thioacetamide was added to the former H-ZIF-67-C@NiCo-LDH dispersion, and ultrasound treatment was continued for 5 minutes to mix thoroughly. The mixture was then stirred and refluxed for 1 hour, followed by vacuum filtration and collection. The sample was washed three times with ethanol and finally dried in a vacuum oven at 60°C for 12 hours to obtain the final sample HZ@NC@Ag2S-2.

[0039] The obtained HZ@NC@Ag2S-2 nanobox composite catalyst showed an adsorption rate of 10.675% for norfloxacin under dark conditions, and a photodegradation rate of 93.219% and a mineralization degree of 85.81% under visible light irradiation, with a degradation rate constant of 0.03967 min. -1 .

[0040] Implementation Case 3 Step 1: 1 g of rhombic dodecahedron ZIF-67 was placed in a well-sealed covered magnetic boat and placed in a tube furnace. The temperature was increased from room temperature to 450 °C at a heating rate of 5 °C / min. The sample was annealed at 450 °C for 4 hours and then cooled to room temperature to obtain purple calcined ZIF-67.

[0041] Step 2: Dissolve 50 mg of calcined ZIF-67 and 150 mg of nickel nitrate hexahydrate in 85 mL of ethanol. Sonicate the solution for 30 min to disperse and mix it thoroughly. Then, transfer the mixture to a 100 mL PTFE-lined stainless steel autoclave and heat it to 120 °C at a rate of 5 °C / min. Hold the temperature at 120 °C for 2 hours to obtain a core-shell structured ZIF-67-C@NiCo-LDH. To further obtain a hollow core-shell structured H-ZIF-67-C@NiCo-LDH with a larger specific surface area, place 100 mg of ZIF-67-C@NiCo-LDH in 80 mL of an ethanol-water solution (ethanol to water volume ratio of 8:3) and sonicate for 30 min. Then, transfer the mixture to a 250 mL three-necked flask and reflux it with stirring for 1 hour. After reflux, the product was washed three times each with ethanol and pure water, vacuum filtered, and then dried in a vacuum oven at 60 °C for 12 hours to obtain the product H-ZIF-67-C@NiCo-LDH.

[0042] Step 3: Using ultrasound treatment, 100 mg of H-ZIF-67-C@NiCo-LDH was dispersed in 80 mL of ethanol. Then, 30 mg of silver nitrate and 16.90 mg of thioacetamide were dissolved in 50 mL of ethanol. After ultrasound treatment for half an hour, the ethanol solution of silver nitrate and thioacetamide was added to the former H-ZIF-67-C@NiCo-LDH dispersion, and ultrasound treatment was continued for 5 minutes to mix thoroughly. The mixture was then stirred and refluxed for 1 hour, followed by vacuum filtration and collection. The sample was washed three times with ethanol and finally dried in a vacuum oven at 60°C for 12 hours to obtain the final sample HZ@NC@Ag2S-3.

[0043] The obtained HZ@NC@Ag2S-3 nanobox composite catalyst showed an adsorption rate of 12.735% for norfloxacin under dark conditions, and a photodegradation rate of 91.068% and a mineralization degree of 83.24% under visible light irradiation, with a degradation rate constant of 0.03626 min. -1 .

Claims

1. A method for preparing a double S-type heterojunction HZ@NC@Ag2S nanobox, characterized in that, Includes the following steps: Step 1: 1 g of rhombic dodecahedron ZIF-67 was loaded into a well-sealed covered magnetic boat, and the covered magnetic boat was placed in a tube furnace. The temperature was raised from room temperature to 450 ℃ at a heating rate of 5 ℃ / min, and annealed at 450 ℃ for 4 h. Then it was cooled to room temperature to obtain purple calcined ZIF-67. Step 2: The calcined ZIF-67 and nickel nitrate hexahydrate were dissolved in 85 mL of ethanol and ultrasonically treated for 30 min to disperse and mix them evenly, resulting in a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and heated to 120 °C at a heating rate of 5 °C / min, and held at 120 °C for 2 h to obtain a core-shell structured ZIF-67-C@NiCo-LDH. 100 mg of the ZIF-67-C@NiCo-LDH was added to 80 mL of an ethanol-water solution and sonicated for 30 min to obtain a dispersion. The ethanol-water solution is prepared by mixing ethanol and water in a volume ratio of 8:

3. The dispersion was transferred to a 250 mL three-necked flask and refluxed for 1 h under stirring. After reflux, it was washed three times with ethanol and pure water, respectively. After vacuum filtration, it was dried in a vacuum oven at 60 °C for 12 h to obtain H-ZIF-67-C@NiCo-LDH. Step 3: 100 mg of the H-ZIF-67-C@NiCo-LDH was ultrasonically dispersed in 80 mL of ethanol to obtain the first dispersion. Silver nitrate and thioacetamide were dissolved in 50 mL of ethanol and sonicated for 30 min to obtain a second solution. The second solution was added to the first dispersion, and the mixture was sonicated for another 5 minutes to ensure homogeneity and obtain a mixture. The mixture was stirred and refluxed for 1 h, then the solid product was collected by vacuum filtration and washed three times with ethanol. Finally, it was dried in a vacuum oven at 60 °C for 12 h to obtain the double S-type heterojunction HZ@NC@Ag2S nanobox.

2. The method for preparing the double S-type heterojunction HZ@NC@Ag2S nanobox according to claim 1, characterized in that, The rhombic dodecahedron ZIF-67 was prepared by the following method: Dissolve 0.1455 g Co(NO3)2·6H2O in 5 mL of methanol to obtain a cobalt nitrate methanol solution; Dissolve 0.1640 g of dimethylimidazole in 5 mL of methanol to obtain a dimethylimidazole methanol solution; The dimethylimidazolium methanol solution was added to the cobalt nitrate methanol solution, and the mixture was stirred at high speed to ensure thorough mixing of the two solutions. Continue stirring at room temperature for 30 minutes, then let stand for 24 hours; After the reaction was completed, the product was collected and washed with methanol and deionized water, respectively. The washed product was then vacuum dried in an oven at 60 °C for 12 h to obtain the rhombic dodecahedron ZIF-67.

3. The method for preparing the double S-type heterojunction HZ@NC@Ag2S nanobox according to claim 1, characterized in that: The total mass of the calcined ZIF-67 and nickel nitrate hexahydrate is 200 mg, and the mass ratio is 1:1 to 3:

1.

4. The method for preparing the double S-type heterojunction HZ@NC@Ag2S nanobox according to claim 1, characterized in that: At least one of the following must be met: The mass ratio of silver nitrate to thioacetamide is 1:0.5 ~ 1; In the silver nitrate and thioacetamide ethanol solution, the total mass ratio of silver nitrate and thioacetamide to the volume ratio of ethanol is 1:1 to 3.

5.

5. A double S-type heterojunction HZ@NC@Ag2S nanobox, characterized in that, The double S-type heterojunction HZ@NC@Ag2S nanoboxes are prepared by the preparation method according to any one of claims 1 to 4; the adsorption rate of norfloxacin for the double S-type heterojunction HZ@NC@Ag2S nanoboxes is greater than 10% under dark conditions, the photodegradation rate under visible light irradiation is greater than 90%, the mineralization is greater than 80%, and the degradation rate constant is 0.035–0.040 min. -1 .

6. The double S-type heterojunction HZ@NC@Ag2S nanobox according to claim 5, characterized in that, The double S-type heterojunction HZ@NC@Ag2S nanobox has a hollow layered structure.

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