A piezoelectric-photocatalyst with oxygen-rich vacancy Bi5O7I microspheres and its preparation method

Abstract

This invention provides an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst and its preparation method, belonging to the field of photo-piezoelectric synergistic catalysis technology. The method involves mixing Bi(NO3)3•5H2O and PEG 6000 powder, dissolving them in anhydrous ethanol, stirring until homogeneous, adding NaI solution dropwise, stirring again until homogeneous, washing and drying sequentially to obtain a dried product, and calcining the dried product to obtain the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst. This invention expands the spectral absorption range of the piezoelectric-photocatalyst by introducing more abundant oxygen vacancies into the Bi5O7I powder, and improves its photocatalytic, piezoelectric, and photo-piezoelectric synergistic catalytic efficiency by utilizing the electron-capturing effect of oxygen vacancies to increase the carrier concentration. The oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst prepared by this invention exhibits highly efficient organic dye degradation performance, with a catalytic effect far superior to that of pure phase Bi5O7I powder.

Description

Technical Field

[0001] This invention relates to the field of photo-plastography synergistic catalysis technology, specifically to an oxygen-rich vacancy Bi5O7I microsphere piezoelectric-photocatalyst and its preparation method. Background Technology

[0002] Nanoscale semiconductor technology, which utilizes nanoscale semiconductor materials to absorb energy from the environment and convert it into chemical energy, has gradually come into focus. In recent years, photocatalysis and piezoelectric catalysis have become research hotspots due to their ability to provide clean energy for the excitation of nanoscale semiconductor materials. With continuous research on photocatalysis and piezoelectric catalysis, it has been found that piezoelectric fields can promote the transport efficiency of electron-hole separators during photocatalysis. Coupled with photocatalysis, this technology helps improve the full utilization of energy by nanoscale semiconductor materials and enhances the degradation of organic pollutants. Xiao et al. applied photo-piezoelectric synergistic catalysis to H2 production, finding that the H2 yield of NBT-BNT@Ag photo-piezoelectric synergistic catalysis increased by 3.1 times and 9.3 times, respectively, compared to photocatalysis and piezoelectric catalysis alone. Zhou et al. applied Bi4Ti3O... 12 In the application of @C catalysts for the degradation of RhB, it was found that Bi4Ti3O4 was more efficient than photocatalysis and piezoelectric catalysis alone in degrading RhB. 12 The photo-pressure synergistic catalytic degradation efficiency of RhB by the @C catalyst was increased by 2.4 times and 2.3 times.

[0003] Bismuth halide, i.e. Bi x O y Z w (Z = Cl, Br, and I), as traditional photocatalysts, has become an important category of ternary V–VI–VII-based oxide semiconductors; Bi x O y Z w The structure of the (Z = Cl, Br, and I) family consists of a [Bi₂O₂] group. 2+ Bi5O7I, a bismuth halogen oxide, has a layered structure with layers interconnected by halogen atoms. This structural arrangement creates an internal electrostatic field perpendicular to each layer. This electrostatic field is highly effective for the intrinsic separation of photogenerated electrons and holes, which is an important guarantee for the excellent performance of photocatalysts in photocatalytic reactions. As a member of the bismuth halogen oxide class, Bi5O7I has been widely used in the field of photocatalysis, but its piezoelectric catalysis has been rarely reported. Considering that its spatial structure belongs to the orthorhombic crystal system, it will also exhibit a certain piezoelectric response capability. However, its large band gap (~3.1 eV) and low carrier separation rate still limit its further application. Summary of the Invention

[0004] The purpose of this invention is to provide an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst and its preparation method, in order to overcome the problems existing in the prior art. This invention expands the spectral absorption range of the piezoelectric-photocatalyst by introducing more abundant oxygen vacancies into Bi5O7I, and improves its photocatalytic, piezoelectric, and photo-piezoelectric synergistic catalytic efficiency by utilizing the electron-capturing effect of oxygen vacancies to increase the carrier concentration. At the same time, the preparation process is simple, and the prepared oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst has highly efficient organic dye degradation performance, and its catalytic effect is far superior to that of pure phase Bi5O7I.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst includes the following steps:

[0007] (1) Mix Bi(NO3)3•5H2O (bismuth nitrate pentahydrate) and PEG 6000 (polyethylene glycol) powder, then dissolve them in anhydrous ethanol, stir evenly, add NaI (sodium iodide) solution dropwise, stir evenly again, and then wash and dry in sequence to obtain the dried product;

[0008] (2) The dried product was calcined to obtain oxygen-vacancy Bi5O7I microsphere piezoelectric-photocatalyst;

[0009] Furthermore, deionized water is used for washing in (1);

[0010] Further, in (1), the molar ratio of Bi(NO3)3•5H2O, PEG 6000, anhydrous ethanol, NaI and deionized water is 1:(0.01~0.03):180.89:1:185.03;

[0011] Furthermore, the concentration of the NaI solution added in (1) is 0.3 mol / L; the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L;

[0012] Furthermore, in step (1), the stirring time for dissolving in anhydrous ethanol is 5 min; the stirring time for adding NaI solution dropwise is 1.5~2 h.

[0013] Furthermore, the drying temperature in (1) is 60~80 ℃ and the drying time is 8~12 h;

[0014] Furthermore, in step (2), the calcination temperature is 500 °C and the calcination time is 2 h;

[0015] Furthermore, the dried product is a BiOI precursor;

[0016] Furthermore, the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst obtained in (2) is oxygen-vacancy-rich Bi5O7I powder.

[0017] An oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst was obtained based on the above-mentioned preparation method of an oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst.

[0018] The above technical solution has the following advantages or beneficial effects:

[0019] This invention provides an oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst and its preparation method. The sample is prepared using a combination of room-temperature precipitation and calcination. The room-temperature precipitation method is simple to operate, and the calcination method involves low temperature and short time, resulting in a relatively simple preparation process, low material cost, and suitability for industrial production. By adding PEG6000 during the preparation of Bi5O7I powder, abundant oxygen vacancies are obtained. On one hand, oxygen vacancies can act as electron trapping centers, promoting electron-hole separation during photocatalysis and carrier separation during piezoelectricity. On the other hand, the addition of PEG6000 gives Bi5O7I a good visible light response, expanding its spectral absorption range and providing more reactive sites, thus improving carrier separation efficiency. The resulting 3D oxygen-vacancy-enriched Bi5O7I piezoelectric-photocatalyst exhibits highly efficient dye degradation performance, and its photo-, piezoelectric, and photo-piezo-co-catalyst synergistic dye degradation efficiency is far superior to that of pure-phase Bi5O7I, demonstrating excellent photocatalytic degradation performance of organic dyes. This oxygen-vacancy-enriched piezoelectric-photocatalyst holds promise for applications in wastewater treatment and other fields.

[0020] Furthermore, deionized water is pure water that has been treated to remove most of the ions. It has very low conductivity and contains almost no dissolved solids or impurities. Using deionized water for washing ensures that impurities and unreacted substances on the surface of the product are effectively removed, while avoiding the introduction of new ion contamination, thereby guaranteeing the purity and performance of the final product.

[0021] Furthermore, the amount of PEG 6000 used as a surfactant or template agent has a significant impact on the morphology and size of the final product. Adjusting the amount of PEG 6000 within the scope of this invention can optimize the sphericity and dispersibility of the microspheres. Anhydrous ethanol is used as a solvent, and its amount must be sufficient to fully dissolve Bi(NO3)3•5H2O and PEG 6000 and form a good reaction system. At the same time, the amount of solvent also affects the concentration and diffusion rate of the reactants, thereby affecting the structure and properties of the product. The molar ratio of Bi(NO3)3•5H2O and NaI is intended to ensure that the reaction proceeds completely and generates the target product BiOI.

[0022] Furthermore, by controlling the concentration of the NaI solution added and the concentration of Bi(NO3)3•5H2O in the solution after washing, it was shown that the washing process not only removed excess impurities and unreacted substances, but also ensured washing efficiency, avoided product loss caused by over-washing, and helped maintain the purity and stability of the product.

[0023] Furthermore, precise control of drying conditions helps maintain the sphericity and pore structure of the microspheres, which can increase the surface area of ​​the catalyst and the number of reactive sites, ensuring the acquisition of high-purity BiOI precursors and thus reducing impurity interference in subsequent steps.

[0024] Furthermore, by controlling appropriate calcination conditions, it is helpful to promote the crystallization process of the product, improve the phase purity of the product, and thus enhance its stability and catalytic activity.

[0025] Furthermore, the BiOI precursor, as a stable intermediate product, is conducive to undergoing the expected chemical reaction during calcination, transforming into the target product, oxygen-rich vacancy Bi5O7I.

[0026] Furthermore, Bi5O7I powder, as a catalyst, possesses excellent catalytic performance due to its unique crystal structure and chemical composition, exhibiting higher light absorption efficiency and stronger charge separation capability. The microsphere morphology not only increases the specific surface area of ​​the catalyst but also promotes the generation of piezoelectric effect through its special structure, thereby forming a synergistic effect with photocatalysis and further improving catalytic efficiency.

[0027] This invention also provides an oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst, prepared by the above-mentioned method. The introduction of oxygen vacancies can significantly improve the light absorption capacity of Bi5O7I, especially in the visible light region. As an electron trap, the oxygen vacancy can capture photogenerated electrons, thereby prolonging the lifetime of photogenerated electrons and holes and reducing their recombination rate, which is beneficial to the redox reaction in the photocatalytic reaction, thus improving the photocatalytic efficiency. The oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst has a broad-spectrum degradation ability for a variety of pollutants. Due to its stable structure and composition, it can still maintain high catalytic activity after multiple uses and has good cycle stability. Attached Figure Description

[0028] Figure 1XRD patterns of Bi5O7I piezoelectric-photocatalysts modified with different amounts of PEG 6000: (a) Bi5O7I; (b) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.01; (c) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02; (d) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.03.

[0029] Figure 2 The UV-Vis diffuse reflectance absorption spectra of Bi5O7I piezoelectric-photocatalysts modified with different amounts of PEG 6000 are shown below: (a) Bi5O7I; (b) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.01; (c) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02; (d) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.03.

[0030] Figure 3 Scanning curves of Bi5O7I and Bi5O7I piezoelectric-photocatalyst modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02 are shown; (a) is the scanning curve of Bi5O7I piezoelectric-photocatalyst; (b) is the scanning curve of Bi5O7I piezoelectric-photocatalyst modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02.

[0031] Figure 4 The electron spin resonance spectra of Bi5O7I and Bi5O7I modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02 are shown.

[0032] Figure 5 Visible light photocatalytic degradation curves of the organic dye Rhodamine B using Bi5O7I piezoelectric-photocatalysts modified with different amounts of PEG 6000; (a) Bi5O7I; (b) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.01; (c) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02; (d) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.03.

[0033] Figure 6The piezoelectric catalytic degradation curves of the organic dye Rhodamine B by Bi5O7I piezoelectric-photocatalyst modified with different amounts of PEG 6000; (a) Bi5O7I; (b) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.01; (c) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02; (d) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.03. Figure 7 Photocatalytic degradation curves of the organic dye Rhodamine B by different amounts of PEG 6000 modified Bi5O7I piezoelectric-photocatalysts; (a) Bi5O7I; (b) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.01; (c) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02; (d) Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.03.

[0034] Figure 8 Comparison of RhB degradation efficiency of Bi5O7I piezoelectric-photocatalysts modified with different amounts of PEG 6000 under different catalytic conditions;

[0035] Figure 9 A comparison of the band structure of Bi5O7I and Bi5O7I modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02, and a schematic diagram of their catalytic degradation mechanism. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] This invention provides a method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, comprising the following steps:

[0040] (1) Mix Bi(NO3)3•5H2O and PEG 6000 powder, then dissolve them in anhydrous ethanol. After stirring for 5 min, add 0.3 mol / L NaI solution dropwise, stir again for 1.5~2 h, wash with deionized water, and dry at 60~80 ℃ for 8~12 h to obtain the precursor BiOI;

[0041] Preferably, the molar ratio of Bi(NO3)3•5H2O, PEG 6000, anhydrous ethanol, NaI and deionized water is 1:(0.01~0.03):180.89:1:185.03;

[0042] Preferably, the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L;

[0043] (2) The precursor BiOI was calcined at 500 °C for 2 h to obtain oxygen-vacancy-rich Bi5O7I powder, namely oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

[0044] Comparative Example 1:

[0045] Bi5O7I was prepared using a two-step method, the specific steps of which are as follows:

[0046] (1) Weigh 1.455 g Bi(NO3)3•5H2O and dissolve it in 25 mL of alcohol, and dissolve 0.446 g NaI in 10 mL of deionized water, and stir each for 5 min;

[0047] (2) Add NaI solution dropwise into Bi(NO3)3•5H2O solution and stir continuously for 1.5 h;

[0048] (3) The BiOI was obtained by centrifugation, washing and drying in sequence;

[0049] (4) Place the BiOI powder in a crucible and calcine it at 500 °C for 2 h to obtain Bi5O7I powder.

[0050] Example 1:

[0051] This invention provides a method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, comprising the following steps:

[0052] (1) Mix 3 mmol Bi(NO3)3•5H2O with 0.03 mmol PEG 6000 powder, then dissolve in 25 mL anhydrous ethanol. After stirring for 5 min, add 10 mL of 3 mmol NaI aqueous solution. Stir again for 1.5 h, then centrifuge and wash with 30 mL deionized water. Dry in a drying oven at 60 ℃ for 12 h to obtain the precursor BiOI.

[0053] Preferably, the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L;

[0054] (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain oxygen-vacancy-rich Bi5O7I powder, namely oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

[0055] Example 2:

[0056] This invention provides a method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, comprising the following steps:

[0057] (1) Mix 3 mmol Bi(NO3)3•5H2O with 0.06 mmol PEG 6000 powder, then dissolve in 25 mL anhydrous ethanol. After stirring for 5 min, add 10 mL of 3 mmol NaI aqueous solution. Stir again for 1.5 h, then centrifuge and wash with 30 mL deionized water. Dry in a drying oven at 60 ℃ for 12 h to obtain the precursor BiOI.

[0058] Preferably, the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L;

[0059] (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain oxygen-vacancy-rich Bi5O7I powder, namely oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

[0060] like Figure 3 The image shows a scanning electron microscope (SEM) image of Bi5O7I piezoelectric-photocatalyst modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02. This image demonstrates that the Bi5O7I prepared by the two-step method has a 3D nanosphere morphology, and the addition of PEG 6000 did not change the 3D nanosphere morphology of Bi5O7I.

[0061] like Figure 4 As shown, the oxygen vacancy signals of Bi5O7I and Bi5O7I modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02 are reflected. Bi5O7I modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02 has a significantly stronger signal, indicating that it has more oxygen vacancies in its lattice. This suggests that it can capture more electrons, thereby promoting electron-hole separation and ultimately improving catalytic performance.

[0062] like Figure 9 As shown, this reflects the degradation mechanism of dyes by Bi5O7I and Bi5O7I modified with Bi(NO3)3•5H2O and PEG 6000 in a molar ratio of 1:0.02. During the catalytic process, the electrons and holes generated are transferred to the conduction band and valence band, respectively. The electrons react with O2 in the conduction band to generate superoxide radicals, which eventually react with the dye to generate CO2 and H2O. The holes react directly with the dye in the valence band to generate CO2 and H2O.

[0063] Example 3:

[0064] This invention provides a method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, comprising the following steps:

[0065] (1) Mix 3 mmol Bi(NO3)3•5H2O with 0.09 mmol PEG 6000 powder, then dissolve in 25 mL anhydrous ethanol, stir for 5 min, add 10 mL aqueous solution of 3 mmol NaI, stir again for 1.5 h, centrifuge and wash with 30 mL deionized water, and dry in a drying oven at 60 ℃ for 12 h to obtain the precursor BiOI;

[0066] Preferably, the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L;

[0067] (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain oxygen-vacancy-rich Bi5O7I powder, namely oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

[0068] like Figure 1 As shown, with the gradual increase of the molar ratio of PEG 6000 to Bi(NO3)3•5H2O during the preparation process, the mass fraction of PEG6000 in the PEG-Bi5O7I photocatalyst increases accordingly. No new diffraction peaks were found in the figure, which proves the successful preparation of the PEG 6000 modified Bi5O7I photocatalyst.

[0069] like Figure 2 As shown, it is demonstrated that the visible light absorption capacity of Bi5O7I piezoelectric-photocatalyst is significantly improved with the increase of PEG 6000 mass fraction, and Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O to PEG 6000 of 1:0.02 has the largest light absorption range.

[0070] like Figure 5 , Figure 6 and Figure 7 As shown, tests on the degradation of the organic dye Rhodamine B (RhB) by visible light, ultrasound, and the combined effect of both revealed that Bi5O7I piezoelectric-photocatalysts modified with a Bi(NO3)3•5H2O and PEG 6000 molar ratio of 1:(0.01~0.03) all exhibited superior visible light degradation efficiency, piezoelectric degradation efficiency, and photo-piezoelectric synergistic degradation efficiency compared to Bi5O7I. Among them, Bi5O7I modified with a Bi(NO3)3•5H2O and PEG 6000 molar ratio of 1:0.02 showed the best photocatalytic degradation performance, piezoelectric catalytic performance, and photo-piezoelectric synergistic catalytic performance.

[0071] like Figure 8 As shown, the degradation rate of RhB was calculated through kinetic simulation, and the degradation rates of different samples under different catalytic conditions were obtained. It was found that the photocatalytic RhB degradation rate of Bi5O7I modified with a molar ratio of Bi(NO3)3•5H2O and PEG 6000 of 1:0.02 was 6.78 times that of Bi5O7I, the piezoelectric catalytic RhB degradation efficiency was 1.88 times that of Bi5O7I, and the photo-piezoelectric synergistic catalytic RhB degradation efficiency was 1.65 times that of Bi5O7I. This is attributed to the addition of PEG 6000 bringing more oxygen vacancies to Bi5O7I.

[0072] Example 4:

[0073] This invention provides a method for preparing an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, comprising the following steps:

[0074] (1) Mix 3 mmol Bi(NO3)3•5H2O with 0.09 mmol PEG 6000 powder, then dissolve in 25 mL anhydrous ethanol, stir for 5 min, add 10 mL aqueous solution of 3 mmol NaI, stir again for 2 h, centrifuge and wash with 30 mL deionized water, and dry in a drying oven at 80 ℃ for 8 h to obtain the precursor BiOI;

[0075] Preferably, the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L;

[0076] (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain oxygen-vacancy-rich Bi5O7I powder, namely oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

[0077] In summary, introducing oxygen vacancies by adding PEG 6000 during the preparation of Bi5O7I is an effective strategy for developing high-efficiency Bi5O7I piezoelectric-photocatalysts. On the one hand, the modification by PEG 6000 can enhance the strong absorption of visible light by Bi5O7I and broaden the spectral absorption range of the catalyst. On the other hand, the addition of PEG 6000 brings abundant oxygen vacancies to Bi5O7I, which can act as electron traps to capture electrons. After the electrons are captured, the electronegativity in the material decreases, thereby accelerating the separation of electrons and holes, achieving effective separation of electrons and holes, inhibiting electron-hole recombination, and also increasing the number of charge carriers, thus improving the catalytic efficiency.

[0078] Finally, it should be noted that the above 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The application of an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst in the photo-pressure synergistic degradation of dyes, characterized in that, The preparation method of the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst includes the following steps: S1, Bi(NO3)3•5H2O and PEG 6000 powder are mixed, then dissolved in anhydrous ethanol, stirred evenly, and then NaI solution is added dropwise. After stirring evenly again, the mixture is washed and dried sequentially to obtain a dried product. The molar ratio of Bi(NO3)3•5H2O to PEG6000 is 1:(0.01~0.03); the concentration of the added NaI solution is 0.3 mol / L; the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L; the drying temperature is 60~80 ℃, and the drying time is 8~12 h. S2, the dried product is calcined to obtain oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst; the calcination temperature is 500 ℃ and the calcination time is 2 h.

2. The application of the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1 in the photo-pressure synergistic degradation of dyes, characterized in that, Deionized water is used for washing in S1.

3. The application of the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1 in the photo-pressure synergistic degradation of dyes, characterized in that, The stirring time for dissolving S1 in anhydrous ethanol is 5 min; the stirring time for adding NaI solution dropwise is 1.5~2 h.

4. The application of the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1 in the photo-pressure synergistic degradation of dyes, characterized in that, The dried product is a BiOI precursor.

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