Synthesis method of two-dimensional monocrystal periodic large-pore zinc oxide photocatalytic material

Abstract

This invention provides a method for synthesizing a two-dimensional single-crystal periodic macroporous zinc oxide photocatalyst, belonging to the field of inorganic nanophotocatalysts. The invention prepares the two-dimensional single-crystal periodic macroporous zinc oxide photocatalyst using a polystyrene template method: a soluble zinc salt is dissolved in methanol to obtain a precursor solution, followed by the addition of a complete cake-shaped PS microsphere template agent. After standing, vacuum degassing is performed to obtain a sample containing the precursor within the gaps of the ordered microsphere template. The sample is then impregnated in a mixed solution of ammonia and methanol and vacuum degassed. The PS template is removed using DMF, and finally, calcined to convert it into zinc oxide. The ZnO-M prepared by this method possesses a two-dimensional sheet-like single-crystal periodic macroporous structure, which greatly improves the specific surface area and carrier mobility, increases the number of active sites for the reaction, and enables highly efficient photocatalytic reactions. This novel synthesis strategy is of considerable reference value for the preparation of single-crystal two-dimensional periodic macroporous photocatalysts.

Description

Technical Field

[0001] This invention belongs to the field of inorganic nanophotocatalysts, specifically relating to a method for synthesizing a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material. Background Technology

[0002] Phenol, a high-content component in disinfectants, is a colorless, highly toxic, and persistently recalcitrant substance. When released into the environment through wastewater, it causes secondary chemical pollution, threatening human health. Ciprofloxacin (CIP), an antibiotic, is also widely found in pharmaceutical wastewater from factories and urban sewage. Therefore, effectively degrading wastewater containing both phenol and ciprofloxacin before it enters the environment has received increasing attention and research. Photocatalysis is a green, environmentally friendly, low-cost, and rapid method for the photocatalytic degradation of organic pollutants in wastewater, and research on photocatalysts has deepened significantly in recent years.

[0003] Zinc oxide, as a common photocatalyst, has many advantages such as strong oxidation and excellent electron carrying capacity, but it has a small specific surface area and poor adsorption performance. In view of this, the present invention is proposed. Summary of the Invention

[0004] The present invention aims to provide a method for synthesizing a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material, which solves the problems of small specific surface area and poor adsorption performance of ordinary ZnO. The two-dimensional macroporous structure constructed by the present invention increases the specific surface area of ​​the photocatalytic material, and the single-crystal structure reduces the obstacle to carrier migration, improves carrier utilization, and further enhances the photocatalytic reaction efficiency of ZnO. The ZnO-M prepared by the method of the present invention has a two-dimensional single-crystal ordered macroporous structure, which can carry out photocatalytic reactions efficiently and greatly promotes the separation of photogenerated carriers, showing significant advantages in the photocatalytic degradation of phenol and CIP antibiotics.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0006] This invention provides a method for synthesizing a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material, comprising the following steps:

[0007] S1. Polyvinylpyrrolidone and styrene are used as raw materials, and an initiator is added to polymerize them to obtain an ordered polystyrene microsphere template;

[0008] S2. Dissolve the soluble zinc salt in methanol to obtain a precursor solution. Add the polystyrene microsphere template to the precursor solution, degas under vacuum, wash and dry to obtain sample 1.

[0009] S3. Place the obtained sample 1 into a mixture of ammonia and methanol, degas under vacuum, wash and dry to obtain sample 2.

[0010] S4. Sample 2 was added to N,N-dimethylformamide to remove the polystyrene microsphere template. After centrifugation, washing and drying, sample 3 was obtained. Sample 3 was then heat-treated to obtain a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

[0011] Furthermore, the polystyrene microsphere template described in S1 is obtained by reacting polyvinylpyrrolidone, deionized water, styrene, and potassium persulfate at 75°C for 24 hours and then filtering.

[0012] Furthermore, the soluble zinc salt mentioned in S2 is any one of Zn(NO3)2·6H2O, ZnCl2, and Zn(CH3COO)2·2H2O.

[0013] Furthermore, the ratio of the soluble zinc salt to the polystyrene microsphere template in S2 is (0.01-0.04):(4-10), mol:g.

[0014] Furthermore, the vacuum degassing pressure in S2 is 5-15 kPa, more preferably 5-8 kPa, and the time is 3-10 min.

[0015] Furthermore, the ammonia water described in S3 reacts with the Zn in sample 1. 2+ The molar ratio is 1:(1-4); the mass fraction of ammonia is 25%-28%.

[0016] Furthermore, the vacuum degassing pressure described in S3 is 5-15 kPa, more preferably 6-10 kPa, and the time is 3-7 min; after vacuum degassing, it needs to be left to stand at 293-303 K for 12-24 h.

[0017] Furthermore, the ratio of N,N-dimethylformamide to polystyrene microsphere template in S4 is 15-25 mL / g.

[0018] Furthermore, the heat treatment described in S4 is to hold at 723-823K for 1-3 hours, with a heating rate of 1-3℃ / min.

[0019] This invention selects polystyrene (PS) microspheres as templates to construct two-dimensional single-crystal periodic macroporous ZnO photocatalytic materials. The prepared ZnO-M has a two-dimensional single-crystal ordered macroporous structure, which significantly improves the specific surface area of ​​the catalyst, increases the number of active sites for the reaction, shortens the migration distance of charge carriers, and reduces the recombination rate of charge carriers, thereby improving the photocatalytic degradation performance of ZnO-M.

[0020] This invention constructs a two-dimensional single-crystal periodic macroporous ZnO photocatalytic material using PS microspheres as a template agent. First, a precursor solution formed by dissolving soluble zinc salt in methanol is filled into the gaps of an ordered PS template, obtaining a sample containing the precursor within the gaps of the ordered microsphere template. Then, the PS template surface is thoroughly washed with methanol to remove residual Zn. 2+ Then, the ammonia solution was filled and impregnated again, by adjusting the Zn... 2+ A specific molar ratio with ammonia allows for a thorough reaction within the interstitial spaces to form Zn(OH)₂ nanosheets. After washing and drying with anhydrous methanol, the PS template is removed by the organic solvent DMF, followed by centrifugation, washing, and drying. Further heat treatment converts Zn(OH)₂ to ZnO and removes organic impurities, ultimately yielding a two-dimensional single-crystal periodic macroporous ZnO photocatalytic material. The single-crystal two-dimensional macroporous structure significantly increases the specific surface area, adds active sites for the reaction, reduces obstacles to carrier migration, and decreases the carrier recombination rate, thereby improving photocatalytic performance. This general synthesis strategy can extend the possibility of growing two-dimensional single-crystal periodic macroporous materials to other functional semiconductor materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention innovatively proposes a two-step impregnation method to prepare single-crystal two-dimensional macroporous ZnO grown in a PS template, which increases the specific surface area, increases the number of active sites for the reaction, reduces the recombination rate of charge carriers, and exhibits excellent photocatalytic ability.

[0023] 2. The symmetrical orientation and structural continuity of the single-crystal network in the two-dimensional single-crystal periodic macroporous ZnO photocatalytic material constructed in this invention make the migration of charge carriers more efficient.

[0024] 3. The two-dimensional single-crystal periodic macroporous ZnO photocatalytic material constructed in this invention has a high porosity due to its macroporous structure, which improves the light utilization rate and further facilitates the photocatalytic reaction. Attached Figure Description

[0025] Figure 1 The XRD pattern of two-dimensional single-crystal periodic macroporous ZnO (ZnO-M).

[0026] Figure 2 This is a SEM image of two-dimensional single-crystal periodic macroporous ZnO (ZnO-M).

[0027] Figure 3 This is a TEM image of two-dimensional single-crystal periodic macroporous ZnO (ZnO-M).

[0028] Figure 4 ZnO-M is used to treat the organic pollutant phenol (4×10). -5 Photocatalytic degradation curve of M under full light.

[0029] Figure 5 The photocatalytic degradation curve of ciprofloxacin (10 mg / L CIP) by ZnO-M under full light is shown. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Example 1

[0033] A two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material includes:

[0034] 1. First, add 500 mL of deionized water and 2.5 g of polyvinylpyrrolidone (PVP) to a 1 L three-necked round-bottom flask, then add 65 mL of styrene (after removing inhibitors). Heat the solution to 75 °C, then add an aqueous solution of K₂S₂O₈ (1 g K₂S₂O₈ / 50 mL H₂O) for 24 hours to initiate the polymerization reaction. The resulting milky white dispersion is ultrasonicated for 30 minutes. Then, it is poured into a filter funnel fitted with an organic filter membrane with a pore size of 0.2 μm, and the negative pressure is controlled at 0.05 MPa. After filtration for 3 days, a solid filter cake is obtained, which is then dried overnight at 50 °C to obtain the PS template.

[0035] 2. Take Zn(NO3)2·6H2O (0.01mol) and add it to 20mL of anhydrous methanol and stir to dissolve to obtain a precursor solution. Then, put a PS template (7g) into the precursor solution, let it stand at room temperature for 1h, degas it under vacuum for 5min (pressure 8kPa), wash it three times with 21mL of anhydrous methanol, and dry it at 323K for 6h to obtain sample 1 containing Zn(NO3)2 in the template.

[0036] 3. Take 0.68 mL of ammonia water (26%), add 9.32 mL of deionized water, and then mix with 10 mL of anhydrous methanol. Add sample 1 to the above ammonia water mixture, degas under vacuum for 5 min (pressure 6 kPa), let stand at room temperature for 18 h to allow the reaction to proceed, wash twice with 14 mL of anhydrous methanol, and dry in an oven at 323 K for 6 h to obtain sample 2.

[0037] 4. Add sample 2 to DMF and stir for 4 hours to remove the PS template (the ratio of DMF to PS template agent is 20 mL / g). After washing several times by centrifugation at 5500 rpm with DMF and anhydrous methanol respectively, dry in an oven at 353 K for 12 hours to obtain sample 3.

[0038] 5. Place sample 3 in a muffle furnace, heat it to 773K at 2℃ / min, hold for 2h, cool to room temperature, and collect the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

[0039] Example 2

[0040] A two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material includes:

[0041] 1. First, add 500 mL of deionized water and 2.5 g of polyvinylpyrrolidone (PVP) to a 1 L three-necked round-bottom flask, then add 65 mL of styrene (after removing inhibitors). Heat the solution to 75 °C, then add an aqueous solution of K₂S₂O₈ (1 g K₂S₂O₈ / 50 mL H₂O) for 24 hours to initiate the polymerization reaction. The resulting milky white dispersion is ultrasonicated for 30 minutes. Then, it is poured into a filter funnel fitted with an organic filter membrane with a pore size of 0.2 μm, and the negative pressure is controlled at 0.05 MPa. After filtration for 3 days, a solid filter cake is obtained, which is then dried overnight at 50 °C to obtain the PS template.

[0042] 2. Take Zn(NO3)2·6H2O (0.02mol) and add it to 20mL of anhydrous methanol and stir to dissolve to obtain a precursor solution. Then, put a PS template (7g) into the precursor solution, let it stand at room temperature for 1h, degas it under vacuum for 5min (pressure 8kPa), wash it three times with 21mL of anhydrous methanol, and dry it at 323K for 6h to obtain sample 1 containing Zn(NO3)2 in the template.

[0043] 3. Take 0.68 mL of ammonia water (26%), add 9.32 mL of deionized water, and then mix with 10 mL of anhydrous methanol. Add sample 1 to the above ammonia water mixture, degas under vacuum for 5 min (pressure 6 kPa), let stand at room temperature for 18 h to allow the reaction to proceed, wash twice with 14 mL of anhydrous methanol, and dry in an oven at 323 K for 6 h to obtain sample 2.

[0044] 4. Add sample 2 to DMF and stir for 4 hours to remove the PS template (the ratio of DMF to PS template agent is 20 mL / g). After washing several times by centrifugation at 5500 rpm with DMF and anhydrous methanol respectively, dry in an oven at 353 K for 12 hours to obtain sample 3.

[0045] 5. Place sample 3 in a muffle furnace, heat it to 773K at 2℃ / min, hold for 2h, cool to room temperature, and collect the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

[0046] Example 3

[0047] A two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material includes:

[0048] 1. First, add 500 mL of deionized water and 2.5 g of polyvinylpyrrolidone (PVP) to a 1 L three-necked round-bottom flask, then add 65 mL of styrene (after removing inhibitors). Heat the solution to 75 °C, then add an aqueous solution of K₂S₂O₈ (1 g K₂S₂O₈ / 50 mL H₂O) for 24 hours to initiate the polymerization reaction. The resulting milky white dispersion is ultrasonicated for 30 minutes. Then, it is poured into a filter funnel fitted with an organic filter membrane with a pore size of 0.2 μm, and the negative pressure is controlled at 0.05 MPa. After filtration for 3 days, a solid filter cake is obtained, which is then dried overnight at 50 °C to obtain the PS template.

[0049] 2. Take ZnCl2 (0.02 mol) and add it to 20 mL of anhydrous methanol and stir to dissolve to obtain a precursor solution. Then, put a PS template (7 g) into the precursor solution, let it stand at room temperature for 1 h, degas it under vacuum for 5 min (pressure 8 kPa), wash it three times with 21 mL of anhydrous methanol, and dry it at 323 K for 6 h to obtain sample 1 containing ZnCl2 in the template.

[0050] 3. Take 0.68 mL of ammonia water (26%), add 9.32 mL of deionized water, and then mix with 10 mL of anhydrous methanol. Add sample 1 to the above ammonia water mixture, degas under vacuum for 5 min (pressure 6 kPa), let stand at room temperature for 18 h to allow the reaction to proceed, wash twice with 14 mL of anhydrous methanol, and dry in an oven at 323 K for 6 h to obtain sample 2.

[0051] 4. Add sample 2 to DMF and stir for 4 hours to remove the PS template (the ratio of DMF to PS template agent is 20 mL / g). After washing several times by centrifugation at 5500 rpm with DMF and anhydrous methanol respectively, dry in an oven at 353 K for 12 hours to obtain sample 3.

[0052] 5. Place sample 3 in a muffle furnace, heat it to 773K at 2℃ / min, hold for 2h, cool to room temperature, and collect the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

[0053] Example 4

[0054] A two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material includes:

[0055] 1. First, add 500 mL of deionized water and 2.5 g of polyvinylpyrrolidone (PVP) to a 1 L three-necked round-bottom flask, then add 65 mL of styrene (after removing inhibitors). Heat the solution to 75 °C, then add an aqueous solution of K₂S₂O₈ (1 g K₂S₂O₈ / 50 mL H₂O) for 24 hours to initiate the polymerization reaction. The resulting milky white dispersion is ultrasonicated for 30 minutes. Then, it is poured into a filter funnel fitted with an organic filter membrane with a pore size of 0.2 μm, and the negative pressure is controlled at 0.05 MPa. After filtration for 3 days, a solid filter cake is obtained, which is then dried overnight at 50 °C to obtain the PS template.

[0056] 2. First, Zn(CH3COO)2·2H2O (0.02mol) was added to 20mL of anhydrous methanol and stirred to dissolve to obtain a precursor solution. Then, a PS template (7g) was placed in the precursor solution, allowed to stand at room temperature for 1h, degassed under vacuum for 5min (pressure 8kPa), washed 3 times with 21mL of anhydrous methanol, and dried at 323K for 6h to obtain sample 1 containing Zn(CH3COO)2 in the template.

[0057] 3. Take 0.68 mL of ammonia water (26%), add 9.32 mL of deionized water, and then mix with 10 mL of anhydrous methanol. Add sample 1 to the above ammonia water mixture, degas under vacuum for 5 min (pressure 6 kPa), let stand at room temperature for 18 h to allow the reaction to proceed, wash twice with 14 mL of anhydrous methanol, and dry in an oven at 323 K for 6 h to obtain sample 2.

[0058] 4. Add sample 2 to DMF and stir for 4 hours to remove the PS template (the ratio of DMF to PS template agent is 20 mL / g). After washing several times by centrifugation at 5500 rpm with DMF and anhydrous methanol respectively, dry in an oven at 353 K for 12 hours to obtain sample 3.

[0059] 5. Place sample 3 in a muffle furnace, heat it to 773K at 2℃ / min, hold for 2h, cool to room temperature, and collect the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

[0060] The product obtained in the above embodiments has the following morphology, structure, and performance: Figures 1-5 As shown.

[0061] Depend on Figure 1 It can be seen that the ZnO-M photocatalytic materials prepared by filling the gaps of PS microspheres with precursors of different concentrations of Zn(NO3)2·6H2O are all pure phase ZnO.

[0062] Depend on Figure 2 It can be seen that two-dimensional single-crystal periodic macropores were successfully constructed, and two-dimensional ordered macropore ZnO-M maintained high porosity and integrity.

[0063] Depend on Figure 3 It can be seen that the two-dimensional single-crystal periodic macroporous ZnO-M has an ordered lamellar macroporous structure and clear and ordered lattice diffraction spots, and the structure is a single crystal structure.

[0064] Depend on Figure 4 , Figure 5 It can be seen that two-dimensional single-crystal periodic macroporous ZnO-M photocatalyzes the organic pollutant phenol (4×10⁻⁶). -5 It exhibited excellent photocatalytic degradation activity during the process of M) and ciprofloxacin (10 mg / L CIP) solution.

[0065] The results of the examples show that the two-dimensional single-crystal periodic macroporous ZnO-M photocatalytic material prepared by the present invention has excellent photocatalytic degradation performance.

[0066] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synthesizing a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material, characterized in that, Includes the following steps: S1. Polyvinylpyrrolidone and styrene are used as raw materials, and an initiator is added to polymerize them to obtain an ordered polystyrene microsphere template; S2. Dissolve the soluble zinc salt in methanol to obtain a precursor solution. Add the polystyrene microsphere template to the precursor solution, degas under vacuum, wash and dry to obtain sample 1. S3. Place the obtained sample 1 into a mixture of ammonia and methanol, degas under vacuum, wash and dry to obtain sample 2. The ammonia water and Zn in sample 1 2+ The molar ratio is 1:(1-4), the vacuum degassing pressure is 5-15 kPa, the time is 3-7 min, and after vacuum degassing, it needs to be left to stand at 293-303 K for 12-24 h. S4. Sample 2 was added to N,N-dimethylformamide to remove the polystyrene microsphere template. After centrifugation, washing and drying, sample 3 was obtained. Sample 3 was then heat-treated to obtain a two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material.

2. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The polystyrene microsphere template described in S1 was obtained by reacting polyvinylpyrrolidone, deionized water, styrene, and potassium persulfate at 75°C for 24 h and then filtering.

3. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The soluble zinc salt mentioned in S2 is any one of Zn(NO3)2·6H2O, ZnCl2, and Zn(CH3COO)2·2H2O.

4. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The ratio of the soluble zinc salt to the polystyrene microsphere template in S2 is (0.01-0.04):(4-10), mol:g.

5. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The vacuum degassing pressure in S2 is 5-15 kPa, and the time is 3-10 min.

6. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The ratio of N,N-dimethylformamide to polystyrene microsphere template in S4 is 15-25 mL / g.

7. The method for synthesizing the two-dimensional single-crystal periodic macroporous zinc oxide photocatalytic material according to claim 1, characterized in that, The heat treatment described in S4 is to hold at 723-823 K for 1-3 h with a heating rate of 1-3 °C / min.

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