Bismuth titanate film with piezoelectric electro-catalysis / super-hydrophobic bifunctional porous structure as well as preparation method and application of bismuth titanate film

Abstract

The invention relates to a piezoelectric electro-catalysis / super-hydrophobic bifunctional porous structure bismuth titanate film and a preparation method and application thereof. Bismuth titanate in the bismuth titanate film is of an inverse opal structure. Bismuth titanate in the bismuth titanate thin film is regulated to be of an inverse opal structure, coupling of the photocatalytic performance and the piezoelectric catalytic performance of the bismuth titanate thin film can be achieved, and therefore cooperation of the two catalytic performance is achieved, and the catalytic effect is greatly improved. In addition, bismuth titanate in the bismuth titanate film is regulated and controlled to be of an inverse opal structure, the bismuth titanate film can have super-hydrophobic performance, and self-cleaning can be achieved.

Description

Technical Field

[0001] The present application relates to the field of catalyst technology, and in particular to a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure and a preparation method and application thereof. Background Art

[0002] The development and utilization of fossil energy has accelerated social development, but at the same time has brought about problems such as shortage of non-renewable energy and water pollution. Water pollution control requires high energy consumption and large investment. It is of great significance to use green energy to reduce water treatment energy consumption.

[0003] Semiconductor catalysts can absorb and utilize sunlight, a green energy source, to catalytically degrade organic matter in wastewater. They have high photocatalytic efficiency and good safety, and can degrade almost all organic pollutants. This makes the development of photocatalytic materials with large specific surface area, high photocatalytic activity, and a wide light response range, as well as economical, effective, and environmentally friendly photocatalytic wastewater treatment technologies, an important part of current research.

[0004] Bismuth titanate (Bi4Ti3O 12 ) is a layered material whose structure consists of bismuth oxide layers ([Bi2O2] 2+ ) and perovskite-like layers ([Bi2Ti3O 10 ] 2- ) regularly stacked, it has a wide absorption spectrum, high photoelectric conversion efficiency, and strong photoelectrochemical activity, and is highly effective in degrading organic pollutants. Photocatalytic degradation of organic pollutants in wastewater can achieve wastewater purification and resource utilization, which is of great significance to water resource and environmental protection.

[0005] Since photogenerated electron-hole pairs, which play a key role in the photocatalytic process, are easily recombinable, the catalytic effect of bismuth titanate still needs to be improved. One of the existing means to solve this problem is to introduce mechanical energy into the photocatalytic process through the piezoelectricity of the material. The built-in electric field generated by the piezoelectricity may reduce the recombination of holes and electrons, thereby effectively separating the carriers and improving the photocatalytic activity. In addition, the generated piezoelectric potential drives electrons into the piezoelectric / solution interface, thereby inducing redox reactions and achieving piezoelectric catalysis, thereby synergistically improving the catalytic performance of the material.

[0006] Existing research has shown that bismuth titanate has good piezoelectric catalytic activity. However, the simultaneous presence of good photocatalytic and piezoelectric catalytic properties does not necessarily mean that synergistic photocatalysis and piezoelectric catalysis can be achieved. It is also possible that the mechanisms of the two are uncoupled or even interfere with each other, resulting in a simple superposition of the two catalytic effects or a weakening of the material's catalytic performance.

[0007] Furthermore, solving the catalyst recovery problem is crucial for the practical application of bismuth titanate. Compared to powdered catalysts, catalyst films can address this issue. However, existing bismuth titanate films are typically not superhydrophobic and lack self-cleaning properties. After a period of use, they become clogged with organic pollutants and microorganisms, leading to a decrease in catalytic activity. Summary of the Invention

[0008] The primary purpose of the present invention is to overcome the problems that the catalytic activity of the above-mentioned existing bismuth titanate films still needs to be improved and self-cleaning is difficult to achieve, and to provide a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure bismuth titanate film.

[0009] A further object of the present invention is to provide a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure.

[0010] Another object of the present invention is to provide the use of the above-mentioned bismuth titanate film in degrading pollutants in water.

[0011] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0012] Studies have shown that bismuth titanate has photocatalytic and piezoelectric catalytic properties. To further enhance the catalytic effect, the inventors of the present invention attempted to perform piezoelectric photocatalysis on existing bismuth titanate, but found that the two catalytic properties could not be coupled, which may be related to the characteristics of the bismuth titanate material itself.

[0013] The inventors of the present invention continued to study and found that by regulating the bismuth titanate in the bismuth titanate film to an inverse opal structure, the photocatalytic performance and piezoelectric catalytic performance of the bismuth titanate film can be coupled, thereby achieving the synergy of the two catalytic properties and greatly improving the catalytic effect.

[0014] In addition, by regulating the bismuth titanate in the bismuth titanate film to an inverse opal structure, the bismuth titanate film can also have superhydrophobic properties and achieve self-cleaning.

[0015] A method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure comprises the following steps: S1. Immersing a conductive substrate in a polymer ball solution to obtain a conductive substrate loaded with a template; S2. Immersing the conductive substrate loaded with the template in a bismuth titanate precursor solution, removing the substrate and performing a heat treatment to remove the polymer spheres, thereby obtaining the piezoelectric photocatalytic / superhydrophobic dual-functional porous structured bismuth titanate film.

[0016] The inventors of the present invention have discovered that by immersing a conductive substrate in a polymer bead solution of a specific concentration to prepare a three-dimensional porous polymer bead layer, and then using the three-dimensional porous polymer bead layer as a template to form a continuous bismuth titanate with an inverse opal structure through an inverse template method, a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure bismuth titanate film is obtained. The bismuth titanate film prepared by this preparation method not only maintains the good photocatalytic activity and piezoelectric catalytic activity of bismuth titanate itself, but also couples the piezoelectric catalytic performance and photocatalytic performance of the bismuth titanate film through morphology regulation, thereby achieving synergy of the two catalytic properties. At the same time, the morphology regulation also makes the bismuth titanate film have superhydrophobic properties, which can achieve self-cleaning.

[0017] In addition, the preparation method of the present invention has simple process and low cost, which is conducive to large-scale application.

[0018] Preferably, the concentration of the polymer bead solution is 50-80 mmol / L.

[0019] Preferably, the step of cleaning the conductive substrate is included before performing step S1.

[0020] More preferably, the cleaning process is: immersing the conductive substrate in piranha solution, and then rinsing with water until the pH is neutral.

[0021] Preferably, the specific process of step S1 is: immersing the conductive surface of the conductive substrate in a polymer ball solution, and then drying to obtain a conductive substrate loaded with a template.

[0022] More preferably, the soaking time is 15-30 h and the temperature is 20-30°C.

[0023] More preferably, the drying time is 12-72 h and the temperature is 30-60°C.

[0024] Preferably, in step S1, the polymer beads are at least one of polystyrene beads or polymethyl methacrylate beads.

[0025] Preferably, in step S1, the diameter of the polymer spheres is 200-500 nm. Controlling the diameter of the polymer spheres within this range is conducive to forming a continuous porous inverse opal structure and having good light absorption capacity, thereby improving the photocatalytic activity, piezoelectric catalytic activity, and piezoelectric photocatalytic activity of the bismuth titanate film.

[0026] Preferably, in step S2, the concentration of bismuth ions in the precursor solution is 0.1-0.3 mol / L.

[0027] Preferably, in step S2, the concentration of the titanium source in the precursor solution is 0.075-0.225 mol / L.

[0028] Preferably, in step S2, the precursor solution contains a titanium source and a bismuth source.

[0029] More preferably, the titanium source is at least one of tetraisopropyl titanate, tetraethyl titanate, tetrabutyl titanate or titanium tetrachloride.

[0030] More preferably, the bismuth source is at least one of bismuth nitrate, bismuth chloride, bismuth sulfate or bismuth sulfide.

[0031] Preferably, in step S2, the solvent in the precursor solution is at least one of acetic acid or ethylene glycol methyl ether.

[0032] More preferably, in step S2, the solvent in the precursor solution is a mixed solvent of acetic acid and ethylene glycol methyl ether in a volume ratio of 1:(0.5-2).

[0033] Preferably, in step S2, the soaking time is 10 to 120 minutes.

[0034] Preferably, in step S2, the soaking temperature is 20-30°C.

[0035] Preferably, in step S2, the heat treatment time is 1 to 3 hours.

[0036] Preferably, in step S2, the temperature of the heat treatment is 450-650°C.

[0037] The present invention also protects the application of the bismuth titanate film in degrading organic pollutants in water.

[0038] Preferably, the organic pollutant is rhodamine B.

[0039] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention regulates the bismuth titanate in the bismuth titanate film to have an inverse opal structure, which can achieve the coupling of the photocatalytic and piezoelectric catalytic properties of the bismuth titanate film, thereby achieving the synergy of the two catalytic properties and greatly improving the catalytic effect. In addition, regulating the bismuth titanate in the bismuth titanate film to have an inverse opal structure can also make the bismuth titanate film superhydrophobic and achieve self-cleaning properties.

[0040] (2) The preparation method of the present invention has simple process and low cost, which is conducive to large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the XRD result of the bismuth titanate film of Example 1.

[0042] Figure 2 This is the SEM image of the bismuth titanate film of Example 1.

[0043] Figure 3 This is a graph showing the photocatalytic test results of the bismuth titanate film of Example 1 on rhodamine B with different treatment times.

[0044] Figure 4 This is a graph showing the piezoelectric catalytic test results of the bismuth titanate film of Example 1 on rhodamine B at different treatment times.

[0045] Figure 5 This is a graph showing the piezoelectric photocatalytic test results of the bismuth titanate film of Example 1 on rhodamine B at different treatment times.

[0046] Figure 6 This is a graph showing the piezoelectric photocatalytic test results of the comparative bismuth titanate film prepared in Comparative Example 1 on Rhodamine B at different treatment times.

[0047] Figure 7 This is a diagram showing the water contact angle test results of the bismuth titanate film of Example 1. DETAILED DESCRIPTION

[0048] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0049] Example 1 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0050] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, comprising the following steps: (1) The FTO glass substrate was immersed in a piranha solution (concentrated sulfuric acid and 30% hydrogen peroxide), and then rinsed with deionized water until the pH was neutral to obtain a clean FTO glass substrate; the conductive surface of the clean FTO glass substrate was immersed in a polystyrene ball solution, and then dried to obtain a FTO glass substrate loaded with a template; wherein the immersion time was 15 h, the temperature was 25 ° C; the drying time was 48 h, the temperature was 60 ° C, the concentration of the polystyrene ball solution was 50 mmol / L, and the diameter of the polystyrene balls in the polystyrene ball layer was 500 nm.

[0051] (2) Bismuth nitrate and tetraisopropyl titanate are added to a mixed solvent (the mixed solvent consists of acetic acid and ethylene glycol methyl ether in a volume ratio of 1:2) to form a precursor solution; wherein the concentration of bismuth ions in the precursor solution is 0.1 mol / L, and the concentration of titanium source in the precursor solution is 0.075 mol / L.

[0052] (3) Immerse the FTO glass substrate loaded with the template in step (1) in the precursor solution, take it out and place it in a muffle furnace for heat treatment to generate bismuth titanate, thereby obtaining a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure; wherein the immersion time is 10 min and the temperature is 25°C; the heat treatment time is 2 h and the temperature is 450°C.

[0053] The bismuth titanate film prepared in this embodiment was subjected to XRD and SEM tests, respectively. Figure 1 and Figure 2 As shown. Figure 1 It can be seen that Example 1 successfully synthesized bismuth titanate on the FTO glass substrate. Figure 2 It can be seen that the bismuth titanate film prepared in Example 1 is composed of multiple layers of porous structure layers, and each porous structure layer is stacked together in an orderly manner, which indicates that the bismuth titanate in the bismuth titanate film in Example 1 is a continuous inverse opal structure.

[0054] Example 2 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0055] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, which differs from Example 1 in that: In step (1), the soaking time is 20 h and the temperature is 20°C; In step (2), the mixed solvent consists of acetic acid and ethylene glycol methyl ether in a volume ratio of 2:1, the concentration of bismuth ions in the precursor solution is 0.3 mol / L, and the concentration of the titanium source is 0.225 mol / L; In step (3), the soaking time is 60 min, the heat treatment time is 1 h, and the temperature is 500°C.

[0056] Example 3 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0057] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, which differs from Example 1 in that: In step (1), the soaking temperature is 30°C; In step (2), the mixed solvent consists of acetic acid and ethylene glycol methyl ether in a volume ratio of 2:3, the concentration of bismuth ions in the precursor solution is 0.2 mol / L, and the concentration of the titanium source is 0.15 mol / L; In step (3), the soaking time is 120 min and the heat treatment temperature is 550°C.

[0058] Example 4 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0059] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, which differs from Example 1 in that: In step (1), the soaking time is 30 h; In step (3), the soaking time is 120 min, the heat treatment time is 3 h, and the temperature is 650°C.

[0060] Example 5 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0061] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, which differs from Example 1 in that: In step (1), the concentration of the polystyrene bead solution is 80 mmol / L.

[0062] Example 6 This embodiment provides a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, wherein the bismuth titanate in the bismuth titanate film has an inverse opal structure.

[0063] This embodiment provides a method for preparing a bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, which differs from Example 1 in that: In step (1), the diameter of the polystyrene beads in the polystyrene bead layer is 200 nm.

[0064] The bismuth titanate films of Examples 2 to 6 were subjected to XRD testing, and the test results were consistent with those of Example 1, indicating that the preparation method of the present invention successfully synthesized bismuth titanate on the FTO glass substrate. The bismuth titanate films of Examples 2 to 6 were subjected to SEM testing, and the test results were consistent with those of Example 1, indicating that the bismuth titanate in the bismuth titanate films of the present invention had a continuous inverse opal structure.

[0065] Comparative Example 1 This comparative example provides a method for preparing a comparative bismuth titanate film, which specifically includes the following steps: (1) Soak the FTO glass substrate in piranha solution (concentrated sulfuric acid and 30% hydrogen peroxide), and then rinse with deionized water until the pH is neutral to obtain a clean FTO glass substrate.

[0066] (2) Bismuth nitrate and tetraisopropyl titanate are added to a mixed solvent (the mixed solvent consists of acetic acid and ethylene glycol methyl ether in a volume ratio of 1:2) to form a precursor solution; wherein the concentration of bismuth ions in the precursor solution is 0.1 mol / L, and the concentration of titanium source in the precursor solution is 0.075 mol / L.

[0067] (3) Place the FTO glass substrate prepared in step (1) on a spin coater and take 0.5 mL of the precursor solution prepared in step (2) and transfer it to the surface of the FTO substrate, spread it evenly, and then spin coat it (rotation speed of 2000 rpm, time of 20 s). Then, place it on a baking table at 400°C for 5 minutes to remove part of the solvent. After baking, cool it to room temperature, repeat the spin coating and baking operations 10 times, and then place the sample in a muffle furnace for heat treatment to generate bismuth titanate, thereby obtaining a comparative bismuth titanate film; wherein, the heat treatment temperature is 450°C and the time is 2 hours. The spin coating and baking in this step are repeated multiple times to ensure that the amount of bismuth titanate in the obtained film is consistent with that in Example 1.

[0068] Performance Testing 1. Photocatalytic activity The bismuth titanate film of Example 1 was used to perform photocatalytic tests on Rhodamine B for different treatment times. The results are shown in Table 1. Figure 3 The test method is as follows: Under dark conditions, the bismuth titanate film was placed in a rhodamine B solution (concentration of 5 mg / L) and stirred for 30 minutes to reach adsorption-desorption equilibrium. Then, a continuous cooling water circulation system was used to maintain the experimental temperature at 20°C and an ultraviolet lamp (output power of 100 mW cm -2 ) was tested, 5 mL of the test solution was extracted every 40 minutes, and the degradation of the solution was measured using a spectrophotometer (Shimadzu UV-3600).

[0069] from Figure 3 It can be seen that as the illumination time increases, the absorbance of the rhodamine B solubility gradually decreases, that is, rhodamine B is gradually degraded, indicating that the bismuth titanate film of Example 1 has good photocatalytic activity. The photocatalytic test results of other examples are similar to those of Example 1, indicating that the bismuth titanate film of the present invention has good photocatalytic activity.

[0070] 2. Piezoelectric catalytic activity The bismuth titanate film of Example 1 was used to perform piezoelectric catalytic tests on Rhodamine B at different treatment times. The results are shown in Figure 4The test method is as follows: a bismuth titanate film is placed in a rhodamine B solution (concentration: 5 mg / L) and stirred for 30 minutes to reach adsorption-desorption equilibrium. A continuous cooling water circulation system is then used to maintain the experimental temperature at 20°C. Testing is performed using an ultrasonic device (piezoelectric source, Prima, PM1-300TD, 40 kHz, 120 W). 5 mL of the test solution is extracted every 40 minutes, and the degradation of the solution is measured using a spectrophotometer (Shimadzu UV-3600).

[0071] from Figure 4 It can be seen that the absorbance of the rhodamine B solubility gradually decreases with the extension of the illumination time, that is, the rhodamine B is gradually degraded, indicating that the bismuth titanate film of Example 1 has good piezoelectric catalytic activity. The piezoelectric catalytic test results of other examples are similar to those of Example 1, indicating that the bismuth titanate film of the present invention has good piezoelectric catalytic activity.

[0072] 3. Piezoelectric photocatalytic activity The bismuth titanate film of Example 1 and the comparative bismuth titanate film prepared in Comparative Example 1 were used to perform piezoelectric photocatalysis tests on Rhodamine B at different treatment times. The results are shown in FIG. Figure 5 and Figure 6 The test method is as follows: a bismuth titanate film is placed in a rhodamine B solution (concentration 5 mg / L) and stirred for 30 minutes to reach adsorption-desorption equilibrium. A continuous cooling water circulation system is then used to maintain the experimental temperature at 20°C. A UV lamp (output power 100 mW cm -2 The test was carried out simultaneously using an ultrasonic machine (piezoelectric source, Prima, PM1-300TD, 40 kHz, 120 W). 5 mL of the test solution was extracted every 40 min, and the degradation of the solution was measured using a spectrophotometer (Shimadzu UV-3600).

[0073] from Figure 5 It can be seen that with the extension of piezoelectric photocatalysis time, the absorbance of Rhodamine B solubility gradually decreases, that is, Rhodamine B is gradually degraded. Further comparison Figure 3 、 Figure 4 and Figure 5 It can be seen that at 160 minutes, the degradation rate of rhodamine B under photocatalysis of the bismuth titanate film of Example 1 is about 38%, the degradation rate of rhodamine B under piezoelectric catalysis is about 25%, and the degradation rate of rhodamine B under piezoelectric photocatalysis is about 88%. The degradation rate of rhodamine B under piezoelectric photocatalysis is greater than the sum of the degradation rates of photocatalysis alone and piezoelectric catalysis alone, indicating that the present invention couples the piezoelectric catalytic performance and photocatalytic performance of the bismuth titanate film, thereby achieving the synergy of the two catalytic properties.

[0074] from Figure 6It can be seen that as the piezoelectric photocatalysis time increases, the absorbance of the Rhodamine B solubility does not decrease significantly, that is, the comparative bismuth titanate film prepared in Comparative Example 1 is difficult to effectively degrade Rhodamine B under piezoelectric photocatalysis. This may be because the morphology of the comparative bismuth titanate film in Comparative Example 1 is not suitable, resulting in the piezoelectric catalytic activity and photocatalytic activity of the material interfering with each other, thereby weakening the catalytic activity.

[0075] 4. Water contact angle Water contact angle measurements were performed on the bismuth titanate films of each example and the comparative bismuth titanate film prepared in Comparative Example 1. The test method was as follows: 5 μL of deionized water was deposited on the surface of the bismuth titanate film using a high-precision syringe. An optical contact angle meter (CA, Dataphysics Instrument GmbH OCA50) was used to capture the droplet profile image and calculate the angle at the solid-liquid-gas three-phase contact point.

[0076] The water contact angle of the comparative bismuth titanate film prepared in Comparative Example 1 is less than 150°, which does not have super hydrophobic properties and cannot achieve self-cleaning effect. The water contact angle of the bismuth titanate film of Example 1 is 169.7°. Figure 7 The water contact angle test results of other examples are all greater than 150°, which shows that the bismuth titanate film of the present invention has super hydrophobic properties and can achieve self-cleaning.

[0077] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A bismuth titanate film with a piezoelectric photocatalytic / superhydrophobic dual-functional porous structure, characterized in that: The bismuth titanate in the bismuth titanate film has an inverse opal structure.

2. The method for preparing the bismuth titanate thin film according to claim 1, characterized in that: The following steps are involved: S1. Immersing a conductive substrate in a polymer ball solution to obtain a conductive substrate loaded with a template; S2. Immersing the conductive substrate loaded with the template in a bismuth titanate precursor solution, removing the substrate and performing a heat treatment to remove the polymer spheres, thereby obtaining the piezoelectric photocatalytic / superhydrophobic dual-functional porous structured bismuth titanate film.

3. The preparation method according to claim 2, wherein The concentration of the polymer bead solution is 50-80 mmol / L.

4. The preparation method according to claim 2, wherein In step S1, the polymer beads in the polymer bead solution are at least one of polystyrene beads or polymethyl methacrylate beads.

5. The preparation method according to claim 2, wherein In step S1, the diameter of the polymer beads in the polymer bead solution is 200-500 nm.

6. The preparation method according to claim 2, wherein In step S2, the concentration of bismuth ions in the precursor solution is 0.1-0.3 mol / L.

7. The preparation method according to claim 2, wherein: In step S2, the precursor solution contains a titanium source and a bismuth source.

8. The preparation method according to claim 2, wherein In step S2, the soaking time is 10 to 120 minutes.

9. The preparation method according to claim 2, wherein: In step S2, the temperature of the heat treatment is 450-650°C.

10. Use of the bismuth titanate film according to claim 1 in degrading organic pollutants in water.

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