Organic-inorganic dual piezoelectric electric field enhanced photocatalytic sponge and preparation method thereof

Abstract

The invention belongs to the technical field of functional material preparation, and particularly relates to an organic-inorganic dual piezoelectric electric field enhanced photocatalytic sponge and a preparation method thereof. Comprising the following steps: (1) dispersing polyvinylidene fluoride in a solvent, and stirring to obtain polyvinylidene fluoride dispersion liquid; (2) adding lead titanate powder and a pore-forming agent, heating and drying to obtain a precipitate B; and (3) washing the precipitate B obtained in the step (2) with water to obtain the photocatalytic sponge. According to the invention, a stress concentration point is formed by utilizing the high deformability of the polyvinylidene fluoride sponge and the rigidity of the lead titanate, and by optimizing the proportion of the polyvinylidene fluoride sponge and the lead titanate, the moderate deformability of the material is maintained, meanwhile, stronger built-in electric field construction is realized, and the optimal photocatalytic performance is realized.

Description

Technical Field

[0001] The invention relates to an organic-inorganic dual piezoelectric electric field enhanced photocatalytic sponge and a preparation method thereof, belonging to the technical field of functional material preparation. Background Art

[0002] Semiconductor photocatalysis plays an important role in environmental energy fields such as sewage treatment, photolysis of water, and carbon dioxide reduction. The principle of photocatalytic reaction is to use photons to excite electrons in the valence band of the semiconductor, causing them to jump to the conduction band and leaving holes in place. However, the photogenerated carriers that the photocatalytic reaction relies on are prone to recombination, causing the photocatalytic material to lose its original performance. The separation of photogenerated carriers can be enhanced and the photocatalytic activity can be improved through methods such as doping and heterojunction. Similarly, the built-in electric field generated by piezoelectric materials can also have the effect of separating photogenerated carriers.

[0003] However, using piezoelectric materials to create built-in electric fields presents challenges. For example, traditional piezoelectric materials are rigid, requiring significant strain to deform them, which limits their further application. Organic piezoelectric materials, due to their flexibility, are more susceptible to deformation, making them suitable candidates. By combining organic piezoelectric materials with inorganic piezoelectric materials, strain can be further increased, thereby enhancing the separation of photogenerated carriers.

[0004] In addition, in terms of structural design, the response of photocatalytic composite materials to external stimuli can be enhanced by designing macroscopic structures that are easier to deform, such as fibers, cilia, sponges, etc., to achieve more efficient piezoelectric field-enhanced photocatalytic reactions. Summary of the Invention

[0005] The present invention provides an organic-inorganic dual piezoelectric field-enhanced photocatalytic sponge and its preparation method. First, the piezoelectric photocatalytic material, lead titanate, is prepared. Then, the organic piezoelectric material, polyvinylidene fluoride, is dissolved, the lead titanate is added, and the mixture is stirred evenly. Finally, white sugar is used as a pore-forming agent to prepare a photocatalytic composite sponge, achieving the effect of enhancing photocatalysis using the organic-inorganic dual piezoelectric field.

[0006] The technical solution adopted by the present invention comprises the following steps:

[0007] Step 1: Take a certain amount of tetrabutyl titanate, dissolve it in ethanol, and stir it for a certain period of time.

[0008] Step 2: Add a certain amount of ammonia water to obtain a white turbid solution, which is washed with water to obtain precipitate A.

[0009] Step 3: dissolve a certain amount of potassium hydroxide and lead nitrate in water, add the precipitate A in step 2 and a certain amount of polyvinyl alcohol solution, and stir for a certain time.

[0010] Step 4: Transfer the solution in step 3 to a hydrothermal kettle for hydrothermal reaction.

[0011] Step 5: Using a common solvent such as ethanol or water as a cleaning agent, centrifugal cleaning is performed to obtain lead titanate powder.

[0012] Step 6: Disperse polyvinylidene fluoride in N,N-dimethylformamide and stir for a certain period of time.

[0013] Step 7: Add a certain amount of lead titanate powder and white sugar to the solution in step 6, heat and dry to obtain precipitate B.

[0014] Step 8: Wash the precipitate B obtained in step 7 with water to obtain a photocatalytic sponge.

[0015] Preferably, in step 1, the volume ratio of tetrabutyl titanate to ethanol is 1:3 to 1:7, and the stirring time is 15 to 60 minutes.

[0016] Preferably, the volume ratio of aqueous ammonia (mass concentration is 28%) in step 2 to the ethanol in step 1 is 1:5 to 1:20.

[0017] Preferably, in step 3, the mass concentration of potassium hydroxide is 20-30%, the mass concentration of lead nitrate is 30-50%, the mass concentration of precipitate A is 10%-40%, the concentration of the polyvinyl alcohol solution is 2 g / L, the volume ratio of the polyvinyl alcohol solution to water is 4:1-5:1, and the stirring time is 15-60 min.

[0018] Preferably, the hydrothermal reaction temperature in step 4 is 180-210° C., and the reaction time is 10-15 h.

[0019] Preferably, the centrifugal speed in step 5 is 8000-12000 r / min, and is repeated 3-5 times.

[0020] Preferably, in step 6, the mass concentration of polyvinylidene fluoride is 10-30%, and the stirring time is 1-3 hours.

[0021] Preferably, the mass concentration of lead titanate in step 7 is 0.1-5%, and the mass of white sugar is 2-4 times that of N,N-dimethylformamide.

[0022] Preferably, the detergent in step 8 is water, and the washing temperature is 50-80°C.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The present invention uses white sugar as a soluble pore-forming agent and combines it with the solvent volatility characteristics of N,N-dimethylformamide (DMF) to prepare a deformable polyvinylidene fluoride sponge structure and construct a hierarchical porous sponge. This not only increases the exposure of active sites, but also promotes the adsorption and diffusion of reactants, reduces mass transfer resistance, and this structure can better absorb mechanical energy to deform, thereby providing a larger piezoelectric potential to enhance the photocatalytic reaction.

[0025] 2. The present invention also utilizes organic piezoelectric materials and inorganic piezoelectric materials to form a composite photocatalytic sponge, utilizing the high deformation capacity of the organic piezoelectric material and the rigidity of the inorganic piezoelectric material to form stress concentration points. By optimizing the ratio of the organic piezoelectric material to the inorganic piezoelectric material, while maintaining the moderate deformation capacity of the material, a stronger built-in electric field is constructed to achieve optimal photocatalytic performance.

[0026] 3. The photocatalytic composite sponge prepared by the present invention can be subjected to reciprocating compression-release deformation and has good sustainability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a comparison chart of the photocatalytic performance of Examples 1 to 4;

[0028] Figure 2 This is a comparison chart of the photocatalytic performance of Example 2 and Comparative Example 1. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and examples.

[0030] In order to further understand the present invention, the present invention is described below in conjunction with embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0031] Example 1

[0032] (1) Take 3.04 mL of tetrabutyl titanate, dissolve it in 17.5 mL of ethanol, and stir for 30 minutes.

[0033] (2) Add 1.75 mL of aqueous ammonia to obtain a white turbid solution, which was washed with water to obtain a precipitate.

[0034] (3) Dissolve 2.4 g potassium hydroxide and 3.2 g lead nitrate in 8.75 mL water, add the precipitate from step 2 and 40 mL 2 g / L polyvinyl alcohol solution, and stir well.

[0035] (4) The solution in step 3 was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 200°C for 12 h.

[0036] (5) Using ethanol and water as cleaning agents, centrifugal cleaning was performed at a centrifugal speed of 8000 r / min, and repeated three times to obtain lead titanate powder.

[0037] (6) Disperse 0.5 g of polyvinylidene fluoride in 2 mL of N,N-dimethylformamide and stir for 2 h.

[0038] (7) Add 20 mg of lead titanate powder and 6 g of white sugar to the solution in step 6, and heat and dry at 65°C for 12 h.

[0039] (8) The precipitate obtained in step 7 was washed with water at a washing temperature of 60° C. to obtain a photocatalytic sponge.

[0040] (9) The photocatalytic sponge prepared in step 8 was subjected to a photocatalytic test using 70 mL of 10 mg / L methyl orange as the target degradation product. A 300 W xenon lamp was used as the light source, and 3 mL of the solution was collected every 10 minutes for concentration analysis.

[0041] Example 2

[0042] (1)-(5) are the same as in Example 1.

[0043] (6) Disperse 0.5 g of polyvinylidene fluoride in 2 mL of N,N-dimethylformamide and stir for 2 h.

[0044] (7) Add 30 mg of lead titanate powder and 6 g of white sugar to the solution in step 6, and heat and dry at 65°C for 12 h.

[0045] (8) The precipitate obtained in step 7 was washed with water at a washing temperature of 60° C. to obtain a photocatalytic sponge.

[0046] (9) The photocatalytic sponge prepared in step 8 was subjected to a photocatalytic test using 70 mL of 10 mg / L methyl orange as the target degradation product.

[0047] Example 3

[0048] (1)-(5) are the same as in Example 1.

[0049] (6) Disperse 0.5 g of polyvinylidene fluoride in 2 mL of N,N-dimethylformamide and stir for 2 h.

[0050] (7) Add 40 mg of lead titanate powder and 6 g of white sugar to the solution in step 6, and heat and dry at 65°C for 12 h.

[0051] (8) The precipitate obtained in step 7 was washed with water at a washing temperature of 60° C. to obtain a photocatalytic sponge.

[0052] (9) The photocatalytic sponge prepared in step 8 was subjected to a photocatalytic test using 70 mL of 10 mg / L methyl orange as the target degradation product.

[0053] Example 4

[0054] (1)-(5) are the same as in Example 1.

[0055] (6) Disperse 0.5 g of polyvinylidene fluoride in 2 mL of N,N-dimethylformamide and stir for 2 h.

[0056] (7) Add 50 mg of lead titanate powder and 6 g of white sugar to the solution in step 6, and heat and dry at 65°C for 12 h.

[0057] (8) The precipitate obtained in step 7 was washed with water at a washing temperature of 60° C. to obtain a photocatalytic sponge.

[0058] (9) The photocatalytic sponge prepared in step 8 was subjected to a photocatalytic test using 70 mL of 10 mg / L methyl orange as the target degradation product.

[0059] Comparative Example 1

[0060] (1) Take 3.04 mL of tetrabutyl titanate, dissolve it in 17.5 mL of ethanol, and stir for 30 minutes.

[0061] (2) Add 1.75 mL of aqueous ammonia to obtain a white turbid solution, which was washed with water to obtain a precipitate.

[0062] (3) Dissolve 2.4 g of potassium hydroxide and 3.2 g of lead nitrate in 8.75 mL of water, add the precipitate from step 2 and 40 mL of 2 g / L polyvinyl alcohol solution, and stir for a certain period of time.

[0063] (4) The solution in step 3 was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 200°C for 12 h.

[0064] (5) Using ethanol and water as cleaning agents, centrifugal cleaning was performed at a centrifugal speed of 8000 r / min, and repeated three times to obtain lead titanate powder.

[0065] (6) Disperse 0.5 g of polyurethane in 2 mL of N,N-dimethylformamide and stir for 2 h.

[0066] (7) Add 30 mg of lead titanate powder and 6 g of white sugar to the solution in step 6, and heat and dry at 65°C for 12 h.

[0067] (8) The precipitate obtained in step 7 was washed with water at a washing temperature of 60° C. to obtain a photocatalytic sponge.

[0068] (9) The photocatalytic sponge prepared in step 8 was subjected to a photocatalytic test using 70 mL of 10 mg / L methyl orange as the target degradation product.

[0069] The photocatalytic test results of the above examples and comparative examples are as follows: Figure 1-Figure 2 shown.

[0070] Figure 1 The following is a comparison chart of the photocatalytic performance of Examples 1 to 4. The lead titanate dosage of Example 1 is 20 mg, the dosage of Example 2 is 30 mg, the dosage of Example 3 is 40 mg, and the dosage of Example 4 is 50 mg. It can be seen from the photocatalytic performance chart that Example 2 can achieve the best performance. Due to the low dosage of Example 1, the photocatalytic performance achieved is poor, and although Examples 3 and 4 contain more photocatalytic materials, on the one hand, the exposure sites of the photocatalytic materials on the surface have reached saturation, and on the other hand, the addition of more photocatalytic materials will destroy the flexibility of the composite material and hinder its deformation. Therefore, it is necessary to accurately control the synergistic effect of the two phases, and the appropriate incorporation ratio enables Example 2 to achieve the best photocatalytic performance.

[0071] Figure 2 This chart compares the photocatalytic performance of Example 2 and Comparative Example 1. The difference between Example 2 and Comparative Example 1 is that Example 2 uses a piezoelectric polyvinylidene fluoride substrate, while Comparative Example 1 uses a non-piezoelectric polyurethane. The results show that the photocatalytic performance of Comparative Example 1 is significantly weaker than that of Example 2, demonstrating the superiority of this organic-inorganic piezoelectric structure.

[0072] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A method for preparing an organic-inorganic dual piezoelectric field-enhanced photocatalytic sponge, characterized in that: The steps include: (1) dispersing polyvinylidene fluoride in a solvent and stirring to obtain a polyvinylidene fluoride dispersion; (2) adding lead titanate powder and pore-forming agent, heating and drying to obtain precipitate B; (3) The precipitate B obtained in step 2 is washed with water to obtain a photocatalytic sponge.

2. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The mass ratio of the polyvinylidene fluoride to lead titanate powder is 50:2-5.

3. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The added amount of the pore-forming agent is 2-4 times the mass of N,N-dimethylformamide.

4. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The concentration of polyvinylidene fluoride in the polyvinylidene fluoride dispersion in step (1) is 10-30%.

5. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The solvent in step (1) is N,N-dimethylformamide.

6. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The pore-forming agent in step (2) is white sugar.

7. The method for preparing the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge according to claim 1, characterized in that: The method for preparing the lead titanate powder in step (2) comprises the following steps: Step 1, dissolving tetrabutyl titanate in ethanol; Step 2, adding ammonia water to obtain a white turbid solution, and washing to obtain precipitate A; Step 3: Dissolve potassium hydroxide and lead nitrate in water, add the precipitate A and polyvinyl alcohol solution in step 2, and stir; Step 4, transferring the solution in step 3 to a hydrothermal kettle for hydrothermal reaction; Step 5: Perform centrifugal washing to obtain lead titanate powder.

8. An organic-inorganic dual piezoelectric field-enhanced photocatalytic sponge prepared by the method according to any one of claims 1 to 7.

9. Use of the organic-inorganic dual piezoelectric field enhanced photocatalytic sponge as claimed in claim 8 in photocatalysis.

Images