Simultaneous construction of bismuth single atoms and oxygen vacancies on the surface of SrBi2Nb2O9 based on alkali etching and application

Abstract

The application discloses a kind of based on alkali etching in SrBi2Nb2O9 Surface synchronous construction bismuth element and oxygen vacancy and application, belong to photocatalytic material field.The catalyst is composed of two-dimensional nanometer sheet structure, and the surface is uniformly distributed with oxygen vacancy and superfine metal bismuth nanoparticles.The catalyst is synthesized by alkali etching assisted one-step hydrothermal method, and by synchronously introducing oxygen vacancy and metal bismuth on SBNO nanosheet, a "capture-transmission" cooperative channel is constructed, and high efficient charge separation efficiency and excellent catalytic activity are exhibited in the process of piezoelectric photocatalytic degradation of antibiotic.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials and relates to a preparation method and application of simultaneously generating bismuth nanoparticles and oxygen vacancies on the surface of a bismuth-based catalyst using alkaline etching. Background Technology

[0002] Low-concentration, highly toxic organic pollutants (such as antibiotics) in water bodies are increasingly attracting attention due to their potential harm to ecosystems and human health. Traditional water treatment methods often fall short of efficiently removing these persistent organic pollutants, highlighting the urgency of developing advanced degradation technologies. Semiconductor photocatalysis technology has shown great potential due to its ability to decompose pollutants using solar energy. However, the rapid recombination of photogenerated electrons and holes severely limits its solar energy conversion efficiency, becoming a key bottleneck for the practical application of this technology. To overcome this problem, researchers have recently focused on piezoelectric photocatalysis technology, which combines the piezoelectric effect with photocatalysis. This technology utilizes mechanical energy such as ultrasonic vibration or fluid flow to induce a piezoelectric potential within the semiconductor, constructing an internal electric field that promotes the efficient separation and migration of photogenerated charge carriers, achieving a synergistic improvement in catalytic performance.

[0003] Piezoelectric photocatalysis can efficiently degrade low-concentration, highly toxic organic pollutants such as antibiotics in water into harmless small molecules, thereby mitigating their harm to ecosystems and human health. Under the synergistic effect of light and ultrasound, superoxide radicals (·O2) are generated on the catalyst surface. - Highly reactive species, such as piezoelectric photocatalysts, can rapidly decompose pollutants through oxidation reactions with antibiotic molecules. Piezoelectric photocatalysts can be used for the efficient removal of low concentrations of antibiotics, which is of great significance for ensuring water environmental safety and promoting the development of green catalysis technologies.

[0004] In recent years, photocatalytic materials have made significant progress in antibiotic degradation, with various catalysts such as TiO2, g-C3N4, SrTiO3, Bi2MoO6, and BiOX (X = Cl, Br, and I) exhibiting excellent conversion activity. Among Bi-based catalysts, SrBi2Nb2O9 still has considerable potential for further research and development. However, current methods for simultaneously constructing oxygen vacancies and elemental bismuth on the surface of such materials generally rely on two- or multi-step synthetic routes. These processes often involve complex precursor preparation or energy-intensive post-processing, increasing synthesis costs and time, and limiting their large-scale application. Therefore, developing a simple, low-energy one-step synthetic strategy is of great significance for optimizing the surface properties of bismuth-based catalysts and expanding their environmental applications. Summary of the Invention

[0005] The treatment of highly toxic organic pollutants such as antibiotics places extremely high demands on catalyst performance. Layered perovskites (also known as Aurivillius-type perovskites) with flexible and tunable structures, especially those composed of [Bi₂O₂], are particularly suitable. 2+ Fluorite-type layers and [SrNb2O7] 2- Perovskite-type materials composed of alternating layers have attracted much attention due to their unique layered structure and built-in electric field properties. While SBNO has been studied to some extent in photocatalytic water splitting and pollutant degradation, its limited absorption of visible light results in relatively low catalytic efficiency and a narrow range of applications. Its potential in piezoelectric photocatalysis, particularly in the degradation performance and mechanisms of emerging pollutants such as antibiotics during advanced oxidation processes, still lacks systematic exploration and requires in-depth research.

[0006] The technical problem to be solved by this invention is to address the aforementioned shortcomings in the prior art by providing a perovskite catalyst containing both oxygen vacancies and metallic bismuth dual active centers, its preparation method, and its applications. The catalyst is composed of a two-dimensional nanosheet structure with oxygen vacancies and ultrafine metallic bismuth nanoparticles uniformly distributed on its surface. This invention employs a one-step alkaline etching strategy, achieving OH- oxidation by controlling the NaOH concentration without the need for an external reducing agent. - Function: To selectively attack [Bi2O2] as an etchant. 2+ The layer introduces lattice distortion and oxygen vacancies, while simultaneously causing the Bi released during etching. 3+ In-situ generation of metallic bismuth allows for simultaneous defect engineering and metal modification. This synthetic method is simple, mild, and energy-efficient, overcoming the limitations of traditional methods that require multiple steps, strong reducing agents, or high-energy-consuming post-processing. The resulting catalyst's microstructure and photoelectric properties enable it to exhibit excellent performance in piezoelectric photocatalytic degradation of antibiotics, which is of great significance for exploring new design strategies for high-performance environmental catalytic materials and promoting the development of water pollution control technologies.

[0007] To address the technical challenges of using environmental nanomaterials in antibiotic removal, the present invention provides the following specific technical solution:

[0008] A perovskite catalyst containing oxygen vacancies and metallic bismuth, the catalyst having the chemical composition of strontium bismuth niobate SrBi₂Nb₂O₉ (SBNO), is assembled from two-dimensional nanosheets with uniformly distributed oxygen vacancies and ultrafine metallic bismuth (Bi₂NO₃) on its surface. 0 Nanoparticles.

[0009] According to the present invention, the nanosheets have a smooth surface, a thickness of 30–55 nm, and a lateral dimension of approximately 400–600 nm. The thickness of the nanosheets gradually increases with the increase of NaOH concentration during the synthesis process.

[0010] According to the present invention, the bismuth nanoparticles have a size of 3.8–4.4 nm and are uniformly anchored in the oxygen-vacancy-rich SBNO surface region, forming a strong metal-support interaction.

[0011] According to the present invention, the catalyst exhibits visible light absorption characteristics. The catalyst also has good crystallinity.

[0012] In this invention, the catalyst is synthesized by a one-step hydrothermal method assisted by alkaline etching. By simultaneously introducing oxygen vacancies and metallic bismuth on SBNO nanosheets, a "capture-transport" synergistic channel is constructed, which exhibits high charge separation efficiency and excellent catalytic activity in the piezoelectric photocatalytic degradation of antibiotics.

[0013] This invention also provides a method for preparing the above-mentioned perovskite catalyst containing oxygen vacancies and metallic bismuth, wherein the method involves mixing a bismuth source, a strontium source, a niobium source, and a reducing agent, and then preparing the catalyst via a hydrothermal reaction.

[0014] According to the present invention, the specific steps of the method are as follows:

[0015] (1) First, dissolve the strontium source and bismuth source in deionized water and stir to obtain solution A;

[0016] (2) A certain amount of NaOH is dissolved in deionized water and stirred, which is defined as mineralizing agent solution B;

[0017] (3) Add solution B from step (2) to solution A from step (1) and stir to form a homogeneous mixed solution C;

[0018] (4) Add niobium source to solution C in step (3) and stir. Transfer the suspension into a high-pressure reactor for hydrothermal reaction.

[0019] (5) The white product obtained was washed several times with deionized water and dried in a drying oven to obtain the oxygen-vacancy and Bi elemental perovskite catalyst.

[0020] According to the present invention, the bismuth source is bismuth nitrate; the strontium source is strontium chloride; and the niobium source is niobium oxide.

[0021] According to the present invention, the molar ratio of the added bismuth source, strontium source and niobium source satisfies the molar ratio of SrBi2Nb2O9, that is, the molar ratio of bismuth, strontium and niobium is 2:1:2.

[0022] According to the present invention, the concentration of NaOH reagent in solution C is 0.1~20 mol / L, and the molar concentration of strontium is 0.005-0.1 mol / L;

[0023] Preferably, the concentration of NaOH reagent in solution C is 3 mol / L; the molar concentration of strontium is 0.02 mol / L.

[0024] According to the present invention, in steps (1), (2), (3), and (4), the stirring time is 5 min and the stirring rate is 500 r / min.

[0025] According to the present invention, in step (4), the temperature of the hydrothermal reaction can be 160-260 °C, and the time of the hydrothermal reaction is 16-48 h.

[0026] Preferably, in step (4), the temperature of the hydrothermal reaction is 220 °C and the time of the hydrothermal reaction is 24 h.

[0027] According to the present invention, the method further includes:

[0028] According to the present invention, in step (5), the post-processing step is to wash five times with a mixture of deionized water and anhydrous ethanol at 500 r / min, centrifuge at 7500 r / min, collect the centrifuged product, and dry it.

[0029] According to the present invention, in step (5), the drying temperature is 70 °C and the drying time is 12 h.

[0030] The present invention also provides the above-mentioned oxygen-vacancy and Bi elemental perovskite catalyst for piezoelectric photocatalysis (light irradiation and ultrasonic vibration) to remove low concentrations of highly toxic antibiotic pollutants.

[0031] According to the present invention, the above-mentioned photocatalysis is carried out under visible light irradiation, that is, under a xenon lamp with a dominant wavelength λ ≥ 420 nm.

[0032] According to the present invention, the light energy density of the xenon lamp is 284 mW·cm⁻¹. -2 .

[0033] According to the present invention, the piezoelectricity described above is performed under the vibration of an ultrasonic instrument.

[0034] According to the present invention, the ultrasonic instrument has a frequency of 40 kHz and a power of 40~300 W.

[0035] Preferably, the ultrasonic instrument has a power of 100 W.

[0036] This invention provides a method for photo / piezoelectric / piezoelectric photocatalytic reduction of ciprofloxacin (CIP), the method comprising the following steps:

[0037] (1) In the standard catalytic activity test, 20.0 mg of the obtained catalyst was dispersed in 100 mL of CIP aqueous solution.

[0038] (2) Stir the suspension for 30 min in the dark to establish an adsorption-desorption equilibrium and ensure that the catalyst, pollutants and water are fully dispersed.

[0039] (3) Then turn on the light / ultrasonic vibration / light and ultrasonic vibration to start the reaction. Take about 5 mL of suspension at predetermined time intervals (e.g., every 20 min).

[0040] (4) Centrifuge at 7500 r / min for 5 minutes to remove catalyst particles.

[0041] (5) The absorbance of the supernatant at 277 nm was measured by a UV-Vis spectrophotometer. Based on the strong absorption characteristics of this characteristic wavelength, the change in pollutant concentration was determined, thereby realizing real-time monitoring of reaction kinetics.

[0042] (6) The degradation efficiency (η) of CIP is calculated by the following formula: η = (1-C / C0) × 100%, where C0 and C represent the initial concentration and residual concentration of CIP, respectively.

[0043] According to the present invention, the concentration of the CIP aqueous solution in step (1) can be 1~50 mg·L. -1 An example is 10 mg·L -1 .

[0044] The beneficial effects of this invention are:

[0045] This invention provides a perovskite catalyst containing oxygen vacancies and elemental Bi, its preparation method, and its applications. The catalyst has the following advantages:

[0046] 1. A one-step hydrothermal method using alkaline etching can easily introduce bismuth and oxygen vacancies onto the surface of SrBi₂Nb₂O₉ photocatalysts by simply adjusting the amount of NaOH added, eliminating the need for a complex two-step synthesis process requiring post-treatment. These oxygen vacancies and bismuth not only affect the optical properties of the material, enhancing its absorption of visible light, but can also become active reaction sites, further promoting the catalytic degradation efficiency of ciprofloxacin. This method facilitates the control of secondary pollution and shows promising application prospects in environmental remediation.

[0047] 2. Using a higher concentration of NaOH during the synthesis process can play a role in selective etching of [Bi₂O₂]. 2+ The layer generates abundant oxygen vacancies, while simultaneously promoting the release of free Bi. 3+ In-situ reduction to metallic bismuth. This one-step engineering resulted in an ideal structure characterized by high-density surface defects and a uniformly dispersed metallic bismuth co-catalyst with a size of approximately 4.3 nm. Crucially, under ultrasonic conditions, the built-in piezoelectric field provided a directional driving force, further promoting electron-hole separation. This effect, synergistic with existing defect sites and the co-catalyst, significantly extended the charge carrier lifetime.

[0048] 3. The purpose of this application is to target the low-concentration, highly toxic antibiotic contaminant ciprofloxacin (CIP). Using equipment such as a UV-Vis spectrophotometer, CIP is monitored in real-time. Under the influence of a SrBi₂Nb₂O₉ catalyst containing oxygen vacancies and elemental Bi, and with visible light irradiation and ultrasonic vibration, CIP gradually degrades into non-toxic small molecules with increasing light exposure time, thereby reducing its concentration and potential hazards. Results show that the catalyst with the best performance achieved degradation rates of 32.7%, 47.9%, and 68.2% of CIP solution within 120 min under piezoelectric / photocatalytic / piezoelectric-photocatalytic conditions, respectively.

[0049] The present invention has a simple operation process, low cost, and can be used efficiently for the rapid photocatalytic degradation of low-concentration, highly toxic antibiotic pollutants, which has a positive role in promoting environmental protection. Attached Figure Description

[0050] Figure 1 The following are powder diffraction (XRD) patterns of the SrBi₂Nb₂O₉ catalyst containing oxygen vacancies and elemental Bi prepared in Example 1: (a) is the XRD pattern of the catalyst prepared with 1 mol / L NaOH, (b) is the XRD pattern of the catalyst prepared with 2 mol / L NaOH, (c) is the XRD pattern of the catalyst prepared with 3 mol / L NaOH, (d) is the XRD pattern of the catalyst prepared with 4 mol / L NaOH, and (e) is the standard PDF card of SrBi₂Nb₂O₉. These powder diffraction patterns are characteristic phase spectra of the compounds. Each compound has a unique diffraction pattern, which is used for specific qualitative analysis of the compounds.

[0051] Figure 2 The images show the surface defect distribution of the SrBi2Nb2O9 catalyst containing oxygen vacancies and elemental Bi prepared in Example 1. (a) shows the surface defect distribution of the catalyst prepared with 1 mol / L NaOH, and (b) shows the surface defect distribution of the catalyst prepared with 3 mol / L NaOH.

[0052] Figure 3 High-resolution transmission electron microscopy (TEM) image of the SrBi₂Nb₂O₹ catalyst containing oxygen vacancies and elemental Bi prepared in Example 1.

[0053] Figure 4 The image shows the CIP photocatalytic degradation efficiency of the SrBi₂Nb₂O₹ catalyst containing oxygen vacancies and elemental Bi prepared in Example 1 under visible light irradiation. The catalyst dosage was 20.0 mg, and the CIP solution concentration was 10 mg / L. The CIP solution concentration was monitored in real time every 20 min using a UV-Vis spectrophotometer and other equipment. Figure 4 (a) shows the change in CIP concentration during the 100 W piezoelectric catalytic degradation of CIP. Figure 4 (b) shows the change in CIP concentration during visible light photocatalytic CIP degradation; Figure 4 (c) in the figure represents the change in CIP concentration during the piezoelectric-photocatalytic degradation of CIP. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0055] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0056] Example 1:

[0057] a. Accurately weighed 1.0 mmol SrCl₂·6H₂O and 2.0 mmol Bi(NO₃)₃·5H₂O are dissolved in 20 mL of deionized water under magnetic stirring to form a clear solution A. Different amounts of the mineralizing agent NaOH are dissolved in 30 mL of deionized water and stirred to form mineralizing agent solution B. Solution B is added to solution A and stirred to form a homogeneous mixed solution C.

[0058] The amount of mineralizing agent NaOH used was calculated based on a total volume of 50 mL of deionized water, with concentrations of 1, 2, 3, and 4 mol·L⁻¹. -1 Therefore, the dosages are 2, 4, 6, and 8 g respectively.

[0059] b. Add 1.0 mmol Nb2O5 to solution C from step a and stir for 30 min. Transfer the resulting homogeneous solution to a 100 mL high-pressure reactor and place it in an oven. Heat the reactor to 220 °C and react for 24 h. Finally, allow it to cool naturally to room temperature. Wash, dry, and grind the sample to obtain the perovskite catalyst strontium bismuth niobate SrBi2Nb2O9.

[0060] Among them, the catalysts prepared according to different concentrations of mineralizing agents are catalysts containing different concentrations of oxygen vacancy defects and surface Bi elemental substances.

[0061] c. Accurately weigh 20.0 mg of the above-prepared SrBi₂Nb₂O₉ and uniformly disperse it in 100 mL of CIP aqueous solution (10 mg·L⁻¹). -1First, the suspension is stirred in the dark for 30 minutes to establish adsorption-desorption equilibrium and ensure adequate dispersion of the catalyst, contaminants, and water.

[0062] d. After adsorption-desorption equilibrium is reached, a xenon lamp is placed above the stirrer as a visible light source (xenon lamp, λ≥ 420nm, PLS-SXE300, Perfect Light, Beijing Bofeilai). For piezoelectric catalysis, an ultrasonic instrument (100 W, 40kHz, KQ2200DB, Kunshan Ultrasonic Instrument Co., Ltd., China) is used to activate the reaction by turning on the light and / or ultrasound. Approximately 5 mL of the suspension is taken at predetermined time intervals (e.g., every 20 minutes) and centrifuged at 7500 r / min for 5 minutes to remove catalyst particles.

[0063] e. The absorbance of the supernatant at 277 nm was measured using a UV-1800PC ultraviolet-visible spectrophotometer. Based on the strong absorption characteristics of this characteristic wavelength, the change in pollutant concentration was determined, thereby realizing real-time monitoring of reaction kinetics.

[0064] Figure 1 The following are powder diffraction (XRD) patterns of the SrBi₂Nb₂O₉ catalyst containing oxygen vacancies and elemental Bi prepared in Example 1: (a) is the XRD pattern of the catalyst prepared with 1 mol / L NaOH, (b) is the XRD pattern of the catalyst prepared with 2 mol / L NaOH, (c) is the XRD pattern of the catalyst prepared with 3 mol / L NaOH, (d) is the XRD pattern of the catalyst prepared with 4 mol / L NaOH, and (e) is the standard PDF card of SrBi₂Nb₂O₉. These powder diffraction patterns are characteristic phase spectra of the compounds. Each compound has a unique diffraction pattern, which is used for specific qualitative analysis of the compounds.

[0065] from Figure 1 As can be seen, all diffraction peaks of samples prepared with different NaOH concentrations can be attributed to the orthorhombic SBNO phase, confirming the successful synthesis of a pure layered perovskite structure.

[0066] Figure 2 The images show the surface defect distribution of the SrBi2Nb2O9 catalyst containing oxygen vacancies and elemental Bi prepared in Example 1. (a) shows the surface defect distribution of the catalyst prepared with 1 mol / L NaOH, and (b) shows the surface defect distribution of the catalyst prepared with 3 mol / L NaOH.

[0067] from Figure 2As can be seen, the EPR spectrum exhibits a distinct symmetric signal at g = 2.003, which is characteristic of unpaired electrons trapped in oxygen vacancies. The intensity of this signal is directly correlated with the oxygen vacancy concentration and shows a consistent trend: (a) < (b). This trend specifically reflects the concentration of paramagnetic active oxygen vacancy sites.

[0068] Figure 3 This is a high-resolution transmission electron microscope (TEM) image of the SrBi₂Nb₂O₹ catalyst containing oxygen vacancies and elemental Bi, prepared in Example 1 using a 3 mol / L NaOH solution.

[0069] from Figure 3 As can be seen, the observed interplanar spacings of 0.327 nm and 0.227 nm are attributed to Bi, respectively. 0 The (012) and (110) crystal planes of the nanoparticles confirm the successful formation of elemental Bi.

[0070] Figure 4 The image shows the CIP photocatalytic degradation efficiency of the SrBi₂Nb₂O₉ catalyst containing oxygen vacancies and elemental Bi, prepared in Example 1 using a 3 mol / L NaOH solution, under ultrasonic and / or visible light irradiation. The catalyst dosage was 20.0 mg, and the CIP solution concentration was 10 mg / L. The CIP solution concentration was monitored in real-time every 20 minutes using a UV-Vis spectrophotometer or similar equipment. Figure 3 In the figure, (a) represents the change in CIP concentration during piezoelectric catalytic CIP degradation at a frequency of 40 kHz and a power of 100 W. Figure 3 (b) shows the change in CIP concentration during visible light photocatalytic CIP degradation; Figure 3 (c) in the figure represents the change in CIP concentration during the piezoelectric-photocatalytic degradation of CIP.

[0071] from Figure 4 As can be seen, under the same reaction conditions, once CIP has been fully absorbed on the catalyst surface and system equilibrium has been established, ultrasonic and / or visible light irradiation begins. From... Figure 4 As can be seen, after the light exposure, the CIP concentration gradually decreased with the extension of ultrasonic and / or light irradiation time. Finally, within 120 min, the SrBi₂Nb₂O₉ catalyst containing oxygen vacancies and elemental Bi prepared in Example 1 with a NaOH solution concentration of 3 mol / L showed degradation rates of 32.7%, 47.9%, and 68.2% for CIP solution under piezoelectric / photocatalytic / piezoelectric-photocatalytic effects, respectively.

[0072] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite catalyst containing oxygen vacancies and metallic bismuth, characterized in that, The catalyst has the chemical composition of strontium bismuth niobate (SrBi₂Nb₂O₉) (SBNO). It is assembled from two-dimensional nanosheets with uniformly distributed oxygen vacancies and ultrafine metallic bismuth (Bi₂NO₃) on its surface. 0 Nanoparticles.

2. The perovskite catalyst containing oxygen vacancies and metallic bismuth according to claim 1, characterized in that, The nanosheets have a smooth surface, a thickness of 30–55 nm, and a lateral dimension of approximately 400–600 nm.

3. A perovskite catalyst containing oxygen vacancies and metallic bismuth according to claim 1, characterized in that, The bismuth nanoparticles, with a size of 3.8–4.4 nm, are uniformly anchored on the oxygen-vacancy-rich SBNO surface region, forming a strong metal-support interaction.

4. A method for preparing a perovskite catalyst containing oxygen vacancies and metallic bismuth according to any one of claims 1-3, characterized in that, (1) First, dissolve the strontium source and bismuth source in deionized water and stir to obtain solution A; (2) A certain amount of NaOH is dissolved in deionized water and stirred, which is defined as mineralizing agent solution B; (3) Add solution B from step (2) to solution A from step (1) and stir to form a homogeneous mixed solution C; (4) Add niobium source to solution C in step (3) and stir. Transfer the suspension into a high-pressure reactor for hydrothermal reaction. (5) The white product was washed and dried in a drying oven to obtain the oxygen-vacancy and Bi elemental perovskite catalyst.

5. The method according to claim 4, characterized in that, The bismuth source is bismuth nitrate; the strontium source is strontium chloride; the niobium source is niobium oxide; the molar ratio of the bismuth source, strontium source and niobium source satisfies the molar ratio of SrBi2Nb2O9, that is, the molar ratio of bismuth, strontium and niobium is 2:1:

2.

6. The method according to claim 4, characterized in that, The concentration of NaOH reagent in solution C is 0.1~20 mol / L, and the molar concentration of strontium is 0.005-0.1 mol / L; preferably, the concentration of NaOH reagent in solution C is 3 mol / L, and the molar concentration of strontium is 0.02 mol / L.

7. The method according to claim 4, characterized in that, In step (4), the temperature of the hydrothermal reaction can be 160-260 ℃, and the time of the hydrothermal reaction is 16-48 h; Preferably, in step (4), the temperature of the hydrothermal reaction is 220 °C and the time of the hydrothermal reaction is 24 h.

8. The method according to claim 4, characterized in that, In step (5), the post-processing step involves washing five times with a mixture of deionized water and anhydrous ethanol at 500 r / min, centrifuging at 7500 r / min, collecting the centrifuged product, and drying it.

9. The application of the perovskite catalyst containing oxygen vacancies and metallic bismuth as described in any one of claims 1-3, for piezoelectric photocatalytic removal of low-concentration, highly toxic antibiotic pollutants.

10. The application according to claim 9, wherein the photocatalysis is carried out under visible light irradiation, i.e., under a xenon lamp with a dominant wavelength λ ≥ 420 nm; the light energy density of the xenon lamp is 284 mW·cm⁻¹. -2 The piezoelectricity is performed under the vibration of an ultrasonic instrument; the ultrasonic instrument has a frequency of 40 kHz and a power of 40~300 W; the ultrasonic instrument power is 100 W.

Images