Preparation method and application method of bismuth-based layered ferroelectric composite material

Abstract

The invention provides a preparation method and an application method of a bismuth-based layered ferroelectric composite material, and belongs to the technical field of materials.The preparation method comprises the steps that bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide and sodium hydroxide are dispersed in deionized water to obtain a mixed solution; reacting the mixed solution at 200-240 DEG C for 20-30 hours to obtain a first reaction product; washing and drying the first reaction product to obtain Bi3TiNbO9; the preparation method comprises the following steps: adding Bi3TiNbO9 and lignin into deionized water, and mixing to obtain a mixture; reacting the mixture at 160-200 DEG C for 20-30 hours to obtain a second reaction product; and washing and drying the second reaction product, and calcining at 300-500 DEG C in a protective atmosphere for 1-4 hours to obtain the bismuth-based layered ferroelectric composite material. The method provided by the invention is simple in process and low in cost, and the prepared bismuth-based layered ferroelectric composite material has excellent photo-electro-catalysis performance and has a good photo-electro-catalysis degradation effect on plastics.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly relates to a preparation method and an application method of a bismuth-based layered ferroelectric composite material. Background Art

[0002] In recent years, the problem of plastic pollution has become increasingly severe, seriously threatening the ecological environment and the sustainable development of human society. It is urgent to develop efficient and green technical means to address this challenge. Although traditional plastic recycling technologies such as thermal catalysis and electrocatalysis have alleviated the plastic pollution problem to a certain extent, they still have problems such as high energy consumption, low efficiency, and poor product selectivity. In this context, as an emerging catalytic method, photo-piezoelectrocatalysis technology can significantly reduce the recombination rate of photo-generated electron-hole pairs through the piezoelectric effect induced by mechanical stress, thereby enhancing the photocatalytic activity of materials.

[0003] Currently, among numerous photo-piezoelectrocatalytic materials, ferroelectric semiconductor materials exhibit great potential in the field of photo-piezoelectrocatalysis. Materials such as BaTiO3, Bi4Ti3O 12 and LiNbO3 have attracted much attention due to their excellent photo-piezoelectric properties. Research shows that the directional migration of photo-generated carriers can be effectively promoted by constructing a local electric field. For this reason, researchers have developed various interface regulation strategies, including methods such as surface modification, heterostructure construction, and co-catalyst modification.

[0004] Among them, Bi3TiNbO9 has attracted much attention due to its excellent piezoelectric properties. However, the relatively wide bandgap of this material limits the excitation efficiency of photo-generated carriers, resulting in its catalytic performance being difficult to meet the actual application requirements. Therefore, modifying Bi3TiNbO9 has become the key to improving its catalytic performance.

[0005] Currently, it has been proven that the combination of carbon-based materials and ferroelectric semiconductors can significantly enhance the photo-piezoelectric synergistic catalytic effect of materials.

[0006] Therefore, developing bismuth-based layered composite materials with excellent catalytic performance and exploring their applications in the field of photo-piezoelectrocatalysis have important scientific research value. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a preparation method and an application method of a bismuth-based layered ferroelectric composite material with simple process, low cost, and excellent photo-piezoelectric catalytic performance.

[0008] To solve the above technical problem, the present invention provides a preparation method of a bismuth-based layered ferroelectric composite material, including the following steps:

[0009] Disperse bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide, and sodium hydroxide in deionized water to obtain a mixed solution;

[0010] React the mixed solution at 200 - 240 °C for 20 - 30 h to obtain a first reaction product;

[0011] Wash and dry the first reaction product to obtain Bi3TiNbO9;

[0012] Add Bi3TiNbO9 and lignin to deionized water and mix to obtain a mixture;

[0013] React the mixture at 160 - 200 °C for 20 - 30 h to obtain a second reaction product;

[0014] Wash and dry the second reaction product, and then calcine it at 300 - 500 °C for 1 - 4 h in a protective atmosphere to obtain a bismuth - based layered ferroelectric composite material.

[0015] Furthermore, the molar ratio of bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide, and sodium hydroxide is 6:2:1:8.

[0016] Furthermore, the mass ratio of Bi3TiNbO9 to lignin is 1:1 - 4:1.

[0017] Furthermore, the lignin is alkaline lignin or / and sodium lignosulfonate.

[0018] Preferably, the mass ratio of Bi3TiNbO9 to lignin is 2:1.

[0019] Preferably, the lignin is alkaline lignin.

[0020] Preferably, the reaction temperature of the mixed solution is 220 °C and the reaction time is 24 h.

[0021] Preferably, the reaction temperature of the mixture is 180 °C and the reaction time is 24 h.

[0022] Preferably, after washing and drying the second reaction product, the calcination temperature in a protective atmosphere is 400 °C and the calcination time is 2 h.

[0023] The present invention also provides an application method of a bismuth - based layered ferroelectric composite material, which is applied to the photo - piezoelectric catalytic degradation of plastics and includes the following steps:

[0024] Disperse the bismuth - based layered ferroelectric composite material and plastics in a reactor filled with deionized water;

[0025] Introduce high - purity argon gas into the reactor to remove the residual air in the solution and the reactor;

[0026] Place the reactor in an ultrasonic cleaner and use a xenon lamp as a light source to simulate sunlight irradiating the sample in the reactor;

[0027] After the reaction is completed, the bismuth-based layered ferroelectric composite material and the plastic are separated and recovered, and the recovered plastic is analyzed and processed.

[0028] Further, the plastic is PVC, PE or PP.

[0029] Further, the power of the ultrasonic cleaner is 180W, 240W or 300W, and the power of the xenon lamp is 300W.

[0030] Preferably, the plastic is PVC.

[0031] Preferably, the power of the ultrasonic cleaner is 240W.

[0032] A preparation method of a bismuth-based layered ferroelectric composite material provided by the present invention uses inexpensive and easily available substances such as bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide, sodium hydroxide, lignin, etc. as raw materials, and can finally obtain the bismuth-based layered ferroelectric composite material through low-temperature heating and calcination reaction. The reaction process is not only simple, but also the reaction conditions are relatively low, without the need for complex reagents. Therefore, the production cost is low and it has high economic benefits.

[0033] Moreover, a bismuth-based layered ferroelectric composite material prepared by the preparation method provided by the present invention has a large specific surface area, uniform pore size distribution, rich active sites, and at the same time shows high stability, excellent photo-piezoelectric catalytic performance, and is stable and efficient in the photo-piezoelectric catalytic degradation of plastics such as PVC, PE, and PP, and has good application prospects. Description of the Drawings

[0034] Figure 1 Flow chart of a preparation method of a bismuth-based layered ferroelectric composite material provided by an embodiment of the present invention;

[0035] Figure 2 XRD patterns of bismuth-based layered ferroelectric composite materials prepared by the preparation methods provided in Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0036] Figure 3 SEM images of bismuth-based layered ferroelectric composite materials prepared by the preparation methods provided in Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0037] Figure 4 Plastic degradation performance diagrams of bismuth-based layered ferroelectric composite materials prepared by the preparation methods provided in Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0038] Figure 5 Infrared diagrams of bismuth-based layered ferroelectric composite materials prepared by the preparation methods provided in Example 2 and Comparative Examples 3-4 of the present invention. Detailed Embodiments

[0039] See Figure 1 , a preparation method of a bismuth-based layered ferroelectric composite material provided by an embodiment of the present invention includes the following steps:

[0040] Step 1) Disperse bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide and sodium hydroxide in deionized water to obtain a mixed solution.

[0041] Among them, the molar ratio of bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide, and sodium hydroxide is 6:2:1:8.

[0042] Step 2) React the mixed solution at 200 - 240 °C for 20 - 30 h to obtain a first reaction product.

[0043] Among them, the reaction of the mixed solution is to transfer the mixed solution to a stainless steel autoclave with a polytetrafluoroethylene lining for reaction.

[0044] As a specific embodiment of the present invention, the reaction temperature of the mixed solution is preferably 220 °C, and the reaction time is preferably 24 h.

[0045] Step 3) Wash and dry the first reaction product to obtain Bi3TiNbO9.

[0046] Step 4) Add Bi3TiNbO9 and lignin to deionized water and mix to obtain a mixture.

[0047] Among them, the mass ratio of Bi3TiNbO9 to lignin is 1:1 - 4:1.

[0048] Among them, the lignin is alkaline lignin or / and sodium lignosulfonate.

[0049] As a specific embodiment of the present invention, the mass ratio of Bi3TiNbO9 to lignin is preferably 2:1.

[0050] As a specific embodiment of the present invention, the lignin is preferably alkaline lignin.

[0051] Step 5) React the mixture at 160 - 200 °C for 20 - 30 h to obtain a second reaction product.

[0052] Among them, the reaction of the mixture is to transfer the mixture to an autoclave with a polytetrafluoroethylene lining for reaction.

[0053] As a specific embodiment of the present invention, the reaction temperature of the mixture is preferably 180 °C, and the reaction time is preferably 24 h.

[0054] Step 6) Wash and dry the second reaction product, and then calcine it at 300 - 500 °C for 1 - 4 h under a protective atmosphere to obtain a bismuth-based layered ferroelectric composite material.

[0055] As a specific embodiment of the present invention, after the second reaction product is washed and dried, the calcination temperature in a protective atmosphere is preferably 400 °C, and the calcination time is preferably 2 h.

[0056] Among them, after the second reaction product is washed and dried, it is calcined in a tube furnace in a protective atmosphere.

[0057] As a specific embodiment of the present invention, the protective atmosphere is an N2 atmosphere.

[0058] The preparation method of a bismuth-based layered ferroelectric composite material provided by the embodiment of the present invention uses cheap and easily available substances such as bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide, sodium hydroxide, and lignin as raw materials, and can finally obtain a bismuth-based layered ferroelectric composite material through calcination reaction at a relatively low temperature. The reaction process is not only simple, but also the reaction conditions are relatively low, and no complex reagents are required. Therefore, the preparation method provided by the present invention has a low production cost and high economic benefits.

[0059] The application method of a bismuth-based layered ferroelectric composite material provided by the present invention is applied to the photo-piezoelectrocatalytic degradation of plastics, and includes the following steps:

[0060] S1: Disperse the bismuth-based layered ferroelectric composite material and the plastic in a reactor filled with deionized water.

[0061] Among them, the plastic is PVC, PE or PP.

[0062] As a specific embodiment of the present invention, the best photo-piezoelectrocatalytic degradation effect can be obtained when the plastic is PVC.

[0063] S2: Pass high-purity argon into the reactor to remove the residual air in the solution and the reactor.

[0064] S3: Place the reactor in an ultrasonic cleaner, and use a xenon lamp as a light source to simulate sunlight irradiating the sample in the reactor;

[0065] Among them, the power of the ultrasonic cleaner is 180 W, 240 W or 300 W, and the power of the xenon lamp is 300 W.

[0066] As a specific embodiment of the present invention, the power of the ultrasonic cleaner is controlled to 240 W, and the best photo-piezoelectrocatalytic degradation effect can be obtained.

[0067] S4: After the reaction is completed, separate and recover the bismuth-based layered ferroelectric composite material and the plastic, and analyze and process the recovered plastic.

[0068] The mechanism of the bismuth-based layered ferroelectric composite prepared by the present invention for the photo-piezoelectrocatalytic degradation of plastics as a catalyst is as follows: When the catalyst is subjected to mechanical stress, the piezoelectric effect induces an internal polarization electric field, driving the separation and migration of charges, and generating abundant active free radicals (such as ·OH, ·O2-, etc.); these free radicals activate the C-H bonds in plastic molecules through oxidation and initiate the cleavage of the C-C main chain. At the same time, under the illumination condition, photocatalysis synergistically enhances the generation efficiency of free radicals, thereby achieving the efficient degradation of polyolefins.

[0069] The following is a specific description of the preparation method and application method of a bismuth-based layered ferroelectric composite provided by the present invention through examples and comparative examples.

[0070] Example 1

[0071] (1) Preparation of Bi3TiNbO9

[0072] At room temperature, first disperse 3 mmol of bismuth nitrate pentahydrate, 1 mmol of titanium dioxide, and 0.5 mmol of niobium pentoxide in deionized water, then add 4 mol / L of sodium hydroxide and stir. Finally, transfer the obtained mixture to a stainless-steel autoclave with a polytetrafluoroethylene lining and react at 220 °C for 24 h. After the reaction, wash the product several times with deionized water and dry it at 60 °C for 12 h to obtain the Bi3TiNbO9 material.

[0073] (2) Preparation of Bi3TiNbO9@AC

[0074] The Bi3TiNbO9@AC material is prepared by loading Bi3TiNbO9 on alkaline lignin, and the mass ratio of Bi3TiNbO9 to alkaline lignin is 4:1.

[0075] Add 0.5 g of Bi3TiNbO9 and 0.125 g of alkaline lignin to deionized water and stir, then transfer the mixture to a polytetrafluoroethylene autoclave and heat it to 180 °C for 24 hours. After the reaction, wash and dry the obtained product. Finally, calcine the prepared product in a tube furnace and then heat it to 400 °C in an N2 atmosphere for 2 h to obtain the bismuth-based layered ferroelectric composite with a ratio of 4:1. Denote it as 4:1Bi3TiNbO9@AC.

[0076] The following method is adopted for the phase evaluation of 4:1Bi3TiNbO9@AC prepared in the examples of the present invention:

[0077] X-ray diffraction (XRD): The crystal structure of the prepared 4:1 Bi3TiNbO9@AC was analyzed using a D8 Advance series X-ray diffractometer from Bruker, Germany. The scanning speed was 5° / min, and the scanning range was 10° - 80°. The XRD pattern of the 4:1 Bi3TiNbO9@AC prepared in the examples of the present invention is as shown in Figure 2 shown.

[0078] Morphology analysis method of the 4:1 Bi3TiNbO9@AC prepared in the examples of the present invention:

[0079] Scanning electron microscopy (SEM): The prepared 4:1 Bi3TiNbO9@AC was tested on a JSM-IT300 series scanning electron microscope from JEOL, Japan. The acceleration voltage was 5 - 20 kV. The SEM pattern of the 4:1 Bi3TiNbO9@AC prepared in the examples of the present invention is as shown in Figure 3 shown.

[0080] (3) Photopiezoelectrocatalytic degradation of plastics using the prepared 4:1 Bi3TiNbO9@AC

[0081] 10 mg of the prepared 4:1 Bi3TiNbO9@AC and an appropriate amount of PVC plastic were evenly dispersed in a reactor filled with deionized water. High-purity argon was introduced to remove the residual air in the solution and the reaction system.

[0082] The reactor was placed in a fixed position in an ultrasonic cleaner, and a xenon lamp was used as a light source to simulate sunlight irradiation of the samples in the reactor for photopiezoelectrocatalytic reaction.

[0083] Among them, the power of the ultrasonic cleaner was controlled at 240 W, and the power of the xenon lamp was controlled at 300 W.

[0084] After the reaction, the bismuth-based layered ferroelectric composite material and the plastic were separated and recovered, and the recovered plastic was analyzed and processed.

[0085] Among them, the degradation performance of the 4:1 Bi3TiNbO9@AC prepared in the examples of the present invention on plastics was analyzed by scanning electron microscopy and infrared testing of the microscopic morphology and structure of the plastics after the reaction. The degradation rate of the plastics by the 4:1 Bi3TiNbO9@AC prepared in the examples of the present invention is as shown in Figure 4 shown.

[0086] Example 2

[0087] The difference between this example and Example 1 is that in the Bi3TiNbO9@AC material prepared by loading alkaline lignin on Bi3TiNbO9, the mass ratio of Bi3TiNbO9 to alkaline lignin is 2:1, and the masses of Bi3TiNbO9 and alkaline lignin are 0.5 g and 0.25 g respectively. That is, the alkaline lignin-loaded Bi3TiNbO9 composite material prepared in the example of the present invention is denoted as 2:1Bi3TiNbO9@AC.

[0088] The XRD pattern of 2:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 2 shown.

[0089] The SEM pattern of 2:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 3 shown.

[0090] The degradation rate of plastics by 2:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 4 shown.

[0091] The infrared spectrum of 2:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 5 shown.

[0092] Example 3

[0093] The difference between this example and Example 1 is that in the Bi3TiNbO9@AC material prepared by loading alkaline lignin on Bi3TiNbO9, the mass ratio of Bi3TiNbO9 to alkaline lignin is 1:1, and the masses of Bi3TiNbO9 and alkaline lignin are 0.5 g and 0.5 g respectively. That is, the alkaline lignin-loaded Bi3TiNbO9 composite material prepared in the example of the present invention is denoted as 1:1Bi3TiNbO9@AC.

[0094] The XRD pattern of 1:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 2 shown.

[0095] The SEM pattern of 1:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 3 shown.

[0096] The degradation rate of plastics by 1:1Bi3TiNbO9@AC prepared in the example of the present invention is as Figure 4 shown.

[0097] Comparative Example 1

[0098] It includes the preparation and performance testing of Bi3TiNbO9 material:

[0099] (1) Preparation of Bi3TiNbO9 material

[0100] At room temperature, first disperse 3 mmol of bismuth nitrate pentahydrate, 1 mmol of titanium dioxide, and 0.5 mmol of niobium pentoxide in deionized water. Secondly, add 4 mol / L sodium hydroxide and stir. Finally, transfer the obtained mixture to a stainless-steel autoclave with a polytetrafluoroethylene lining and react at 220 °C for 24 h. After the reaction, wash the product several times with deionized water and dry at 60 °C for 12 h to obtain the Bi3TiNbO9 material.

[0101] The method for evaluating the phase of the Bi3TiNbO9 material prepared in the comparative example of the present invention is as follows:

[0102] X-ray diffraction (XRD): Analyze the crystal structure of the prepared Bi3TiNbO9 material on a D8 Advance series X-ray diffractometer of Bruker Company in Germany. The scanning speed is 5° / min, and the scanning range is 10° - 80°. The XRD pattern of the Bi3TiNbO9 material prepared in the comparative example of the present invention is as Figure 2 shown.

[0103] The method for analyzing the morphology of the Bi3TiNbO9 material prepared in the comparative example of the present invention:

[0104] Scanning electron microscopy (SEM): Test the prepared Bi3TiNbO9 material on a JSM-IT300 series scanning electron microscope of JEOL Company in Japan. The acceleration voltage is 5 - 20 kV. The SEM pattern of the Bi3TiNbO9 material prepared in the comparative example of the present invention is as Figure 3 shown.

[0105] (2) Performance testing of the Bi3TiNbO9 material

[0106] Take 10 mg of the prepared Bi3TiNbO9 material and uniformly disperse it with an appropriate amount of PVC plastic in a reactor filled with deionized water. Pass high-purity argon to remove the residual air in the solution and the reaction system.

[0107] Place the reactor in a fixed position in an ultrasonic cleaner, use a xenon lamp as the light source to simulate sunlight irradiating the sample in the reactor, and carry out photo-electrocatalytic reaction.

[0108] Among them, the power of the ultrasonic cleaner is controlled at 240 W, and the power of the xenon lamp is controlled at 300 W.

[0109] After the reaction, separate and recover the bismuth-based layered ferroelectric composite material and the plastic, and analyze and process the recovered plastic.

[0110] Among them, for the degradation performance of the Bi3TiNbO9 material prepared in the comparative example of the present invention on plastics, the microscopic morphology and structure of the plastics after the reaction were analyzed by scanning electron microscopy and infrared testing. The degradation rate of the Bi3TiNbO9 material prepared in the comparative example of the present invention on plastics is as Figure 4 shown.

[0111] Comparative Example 2

[0112] The difference between this comparative example and Example 2 is that Bi3TiNbO9@LS material was prepared by loading Bi3TiNbO9 with sodium lignosulfonate, and the mass ratio of Bi3TiNbO9 to sodium lignosulfonate is 2:1. During the preparation process, the masses of Bi3TiNbO9 and sodium lignosulfonate are 0.5 g and 0.25 g respectively. The composite material prepared in the comparative example of the present invention is denoted as 2:1 Bi3TiNbO9@LS.

[0113] The SEM pattern of 2:1 Bi3TiNbO9@LS prepared in the comparative example of the present invention is as Figure 3 shown.

[0114] The degradation rate of 2:1 Bi3TiNbO9@LS prepared in the comparative example of the present invention on plastics is as Figure 4 shown.

[0115] Comparative Example 3

[0116] In this comparative example, Bi3TiNbO9@AC material was prepared by loading Bi3TiNbO9 with alkaline lignin, and the mass ratio of Bi3TiNbO9 to alkaline lignin is 2:1. The composite material prepared in this comparative example is denoted as 2:1 Bi3TiNbO9@AC.

[0117] The difference between this comparative example of the present invention and Example 2 is that the power of the ultrasonic cleaner was controlled at 180 W during the performance test.

[0118] The degradation rate of 4:1 Bi3TiNbO9@AC prepared in the comparative example of the present invention on plastics is as Figure 4 shown.

[0119] Comparative Example 4

[0120] In this comparative example, Bi3TiNbO9@AC material was prepared by loading Bi3TiNbO9 with alkaline lignin, and the mass ratio of Bi3TiNbO9 to alkaline lignin is 2:1. The composite material prepared in this comparative example is denoted as 2:1 Bi3TiNbO9@AC.

[0121] The difference between this comparative example of the present invention and Example 2 is that the power of the ultrasonic cleaner was controlled at 300 W during the performance test.

[0122] The degradation rate of the 4:1 Bi3TiNbO9@AC obtained in the comparative example of the present invention for plastics is as Figure 4 shown.

[0123] From Figure 2 it can be seen that by performing XRD tests on the material samples prepared in Examples 1-3 and Comparative Examples 1-2, the material samples prepared in Examples 1-3 and Comparative Examples 1-2 all correspond to the standard card of Bi3TiNbO9, indicating that pure phases were prepared in Examples 1-3 and Comparative Examples 1-2. The diffraction patterns of the samples after carbon loading in Examples 1-3 and Comparative Example 2 are similar to those of the samples without carbon loading, which indicates that carbon loading does not change the crystal phase structure of Bi3TiNbO9.

[0124] See Figure 3 , by performing SEM tests on the material samples prepared in Examples 1-3 and Comparative Examples 1-2, it can be seen that the samples of Examples 1-3 and Comparative Examples 1-2 all exhibit a nanosheet morphology. Among them, in Examples 1-3 and Comparative Example 2, the carbon layer is uniformly loaded on the surface of the nanosheets, forming a good composite structure. However, when the carbon content is too high, uniformly sized carbon spheres will adhere to the surface of the nanosheets. This morphological feature indicates the successful loading of the carbon material.

[0125] See Figure 4 , by performing SEM tests on the PVC plastics before and after degradation using the material samples prepared in Examples 1-3 and Comparative Examples 1-2, it can be seen that the surface of the untreated PVC plastic is relatively smooth and flat, while after adding the material samples prepared in Examples 1-3 and Comparative Examples 1-2 as catalysts, a large number of pits, holes, and obvious cracking phenomena appear on the PVC surface. Among them, the material sample prepared in Example 2 exhibits the highest photo-piezoelectrocatalytic degradation activity for PVC. The above results directly confirm the successful degradation of PVC plastic under photo-piezoelectrocatalysis.

[0126] See Figure 5 , by performing infrared tests on the material samples prepared in Example 2 and Comparative Examples 3-4, it can be seen that after adding the material samples prepared in Example 2 and Comparative Examples 3-4 as catalysts to the PVC plastic, the peak intensity of the C-C main chain in the PVC weakens. Among them, the C-C peak intensity of Example 2 is the smallest, showing the highest photo-piezoelectrocatalytic degradation ability. This result indicates that the catalytic reaction conditions in Example 2 are relatively optimal.

[0127] From the comparison of the above data, it can be seen that compared with the pure Bi3TiNbO9 sample of Comparative Example 1, the different ratio Bi3TiNbO9@AC composite materials prepared in Examples 1-3 have better catalytic activity, and among them, the Bi3TiNbO9@AC composite material prepared in Example 2 has the highest degradation rate for PVC.

[0128] Moreover, compared with Comparative Example 2, Example 2 changed the variable of carbon material, further indicating that the preparation conditions of Example 2 are better.

[0129] Compared with Comparative Example 3 and Comparative Example 4, Example 2 changed the variable of ultrasonic power, further indicating that the reaction conditions of Example 2 are better.

[0130] It can be seen that the Bi3TiNbO9@AC composite material prepared by the preparation method provided by the present invention has excellent photo-piezoelectrocatalytic activity, and the preparation method is simple, the loading ratio is controllable during the reaction process, and the preparation method of the present invention has good industrialization prospects.

[0131] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A preparation method of a bismuth-based layered ferroelectric composite material, characterized in that, It includes the following steps: Disperse bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide and sodium hydroxide in deionized water to obtain a mixed solution; React the mixed solution at 200 - 240 °C for 20 - 30 h to obtain a first reaction product; Wash and dry the first reaction product to obtain Bi3TiNbO9; Add Bi3TiNbO9 and lignin to deionized water and mix to obtain a mixture; React the mixture at 160 - 200 °C for 20 - 30 h to obtain a second reaction product; Wash and dry the second reaction product, and then calcine it at 300 - 500 °C for 1 - 4 h in a protective atmosphere to obtain a bismuth-based layered ferroelectric composite material.

2. The preparation method of the bismuth-based layered ferroelectric composite material according to claim 1, wherein: The molar ratio of bismuth nitrate pentahydrate, titanium dioxide, niobium pentoxide and sodium hydroxide is 6:2:1:

8.

3. The preparation method of the bismuth-based layered ferroelectric composite material according to claim 1, wherein: The mass ratio of Bi3TiNbO9 to lignin is 1:1 - 4:

1.

4. The preparation method of the bismuth-based layered ferroelectric composite material according to claim 3, wherein: The lignin is alkaline lignin or / and sodium lignosulfonate.

5. The preparation method of the bismuth-based layered ferroelectric composite material according to claim 4, wherein: The mass ratio of Bi3TiNbO9 to lignin is 2:1; the lignin is alkaline lignin.

6. The preparation method of the bismuth-based layered ferroelectric composite material according to claim 1, wherein: The reaction temperature of the mixed solution is 220 °C and the reaction time is 24 h; the reaction temperature of the mixture is 180 °C and the reaction time is 24 h; the calcination temperature of the second reaction product after washing and drying in a protective atmosphere is 400 °C and the calcination time is 2 h.

7. A method for applying a bismuth-based layered ferroelectric composite material, which is applied to the photo-piezoelectrocatalytic degradation of plastics, is characterized in that, It includes the following steps: Disperse the bismuth-based layered ferroelectric composite material and plastic in a reactor filled with deionized water; Introduce high-purity argon gas into the reactor to remove the residual air in the solution and the reactor; Place the reactor in an ultrasonic cleaner and use a xenon lamp as a light source to simulate sunlight irradiating the sample in the reactor; After the reaction, separate and recover the bismuth-based layered ferroelectric composite material and plastic, and analyze and process the recovered plastic.

8. The application method of the bismuth-based layered ferroelectric composite material according to claim 7, characterized in that: The plastic is PVC, PE or PP.

9. The application method of the bismuth-based layered ferroelectric composite material according to claim 8, characterized in that: The power of the ultrasonic cleaner is 180 W, 240 W or 300 W, and the power of the xenon lamp is 300 W.

10. The application method of the bismuth-based layered ferroelectric composite material according to claim 9, characterized in that: The plastic is PVC and the power of the ultrasonic cleaner is 240 W.

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