Oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst and preparation method thereof

Abstract

The invention provides an oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst and a preparation method thereof, and belongs to the technical field of light pressure concerted catalysis, and the preparation method comprises the following steps: mixing Bi (NO3) 35H2O and PEG 6000 powder, dissolving in absolute ethyl alcohol, uniformly stirring, dropwise adding a NaI solution, uniformly stirring again, sequentially washing and drying to obtain a dried product, and calcining the dried product to obtain the oxygen-vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst. The Bi5O7I microsphere piezoelectric-photocatalyst rich in oxygen vacancy is obtained; according to the invention, richer oxygen vacancies are introduced into the Bi5O7I powder, the spectral absorption range of the piezoelectric-photocatalyst is expanded, and the concentration of current carriers is improved by utilizing the capturing effect of the oxygen vacancies on electrons, so that the photocatalytic, piezoelectric catalytic and light-pressure synergistic catalytic efficiency of the piezoelectric-photocatalyst is improved; the oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst prepared by the preparation method disclosed by the invention has efficient organic dye degradation performance, and the catalytic effect of the oxygen-vacancy-enriched Bi5O7I microsphere piezoelectric-photocatalyst is far superior to that of pure-phase Bi5O7I powder.

Description

Technical Field

[0001] The present invention relates to the technical field of photo-pressure synergistic catalysis, and in particular to an oxygen-rich vacancy Bi 5 O 7 I. Microsphere piezoelectric-photocatalyst and its preparation method. Background Art

[0002] Nano-semiconductor technology can use nano-semiconductor materials to absorb energy from the environment and convert it into chemical energy, which has gradually entered people's field of vision. In recent years, photocatalysis and piezoelectric catalysis have become research hotspots because they can provide energy as environmental clean energy to stimulate nano-semiconductor materials. With the continuous research on photocatalysis and piezoelectric catalysis, it has been found that piezoelectric electric field can promote the efficiency of electron-hole separation in the photocatalytic process. Coupling piezoelectric catalysis with photocatalysis can help improve the full utilization of energy by nano-semiconductor materials and improve the degradation of organic pollutants. Xiao et al. applied light-pressure synergistic catalysis to produce H 2 In this work, it was found that compared with the separate photocatalytic and piezocatalytic H 2 Yield, NBT-BNT@Ag photo-pressure synergistic H 2 The yields were increased by 3.1 and 9.3 times respectively; Zhou et al. 4 Ti 3 O 12 @C catalyst was used for the degradation of RhB. It was found that the efficiency of Bi@C catalyst for the degradation of RhB was higher than that of photocatalysis and piezoelectric catalysis alone. 4 Ti 3 O 12 The efficiency of photo-pressure synergistic catalytic degradation of RhB over @C catalyst was increased by 2.4 and 2.3 times.

[0003] Bismuth oxyhalide, i.e. Bi x O y Z w (Z = Cl, Br and I), as a traditional photocatalyst, 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 is composed of a [Bi 2 O 2 ] 2+ The layered structure is composed of layers, which are interconnected by double layers of halogen atoms. Due to this structural arrangement, an internal electrostatic field perpendicular to each layer is established; this electrostatic field is very 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 oxyhalide category, Bi 5 O7 I has been widely used in the field of photocatalysis, but its research in the field of piezoelectric catalysis has rarely been reported. Considering that its spatial structure belongs to the orthorhombic space crystal system, it will also show a certain piezoelectric response ability. However, its large bandgap width (~3.1 eV) and low carrier separation rate still limit its further application. Summary of the invention

[0004] The purpose of the present invention is to provide an oxygen-rich vacancy Bi 5 O 7 I microsphere piezoelectric-photocatalyst and its preparation method, in order to overcome the problems existing in the prior art, the present invention is 5 O 7 I introduces more abundant oxygen vacancies to expand the spectral absorption range of the piezoelectric-photocatalyst, and utilizes the capture effect of oxygen vacancies on electrons to increase the concentration of carriers to improve its photocatalytic, piezoelectric and light-pressure synergistic catalytic efficiency. At the same time, the preparation process is simple, and the prepared oxygen-rich Bi 5 O 7 I microsphere piezoelectric-photocatalyst has the performance of efficient organic dye degradation, and its catalytic effect is far better than that of pure phase Bi 5 O 7 I.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A kind of oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Change Bi(NO 3 ) 3 •5H 2 O (bismuth nitrate pentahydrate) and PEG 6000 (polyethylene glycol) powders are mixed, then dissolved in anhydrous ethanol, stirred evenly, and then NaI (sodium iodide) solution is dropped into the mixture, stirred evenly again, and then washed and dried in sequence to obtain a dry product; (2) Calcinate the dried product to obtain oxygen-rich Bi 5 O 7 I microsphere piezoelectric-photocatalyst; Furthermore, deionized water is used for washing in (1); Furthermore, in (1), Bi(NO 3 ) 3 •5H 2 The molar ratio of O, PEG 6000, anhydrous ethanol, NaI and deionized water is 1:(0.01-0.03):180.89:1:185.03; Furthermore, the concentration of the NaI solution added dropwise in (1) is 0.3 mol / L; the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L; Furthermore, the stirring time of dissolving in anhydrous ethanol in (1) is 5 min; the stirring time of dropping NaI solution again is 1.5-2 h; Furthermore, in (1), the drying temperature is 60-80°C and the drying time is 8-12 h; Furthermore, in said (2), the calcination temperature is 500°C and the calcination time is 2 h; Further, the dried product is a BiOI precursor; Furthermore, the oxygen-rich vacancy Bi obtained in (2) 5 O 7 I Microsphere Piezoelectric-Photocatalyst is Oxygen Vacancy-Rich Bi 5 O 7 I powder.

[0006] A kind of oxygen-rich vacancy Bi 5 O 7 I microsphere piezoelectric-photocatalyst, based on the above-mentioned oxygen-rich Bi 5 O 7 The preparation method of I microsphere piezoelectric-photocatalyst is obtained.

[0007] The above technical solution has the following advantages or beneficial effects: The present invention provides an oxygen-rich vacancy Bi 5 O 7 I microsphere piezoelectric-photocatalyst and its preparation method, the sample is prepared by adopting room temperature precipitation method combined with calcination method; the room temperature precipitation method is simple to operate, the calcination method has low calcination temperature and short time, the preparation process is relatively simple, the material cost is low, and it is suitable for industrial production; by Bi 5 O 7 During the preparation of I powder, PEG6000 was added to obtain abundant oxygen vacancies. On the one hand, oxygen vacancies can serve as electron capture centers, promoting the separation of electrons and holes in the photocatalytic process and carriers in the piezoelectric process; on the other hand, the addition of PEG 6000 makes Bi 5 O 7 I has good visible light response, which expands its spectral absorption range. 5 O 7 I obtained more reactive active sites, improved the carrier separation efficiency, and finally obtained 3D oxygen-rich vacancy Bi 5 O 7I piezoelectric-photocatalyst has the performance of efficient dye degradation, and its light, piezoelectric and photo-pressure synergistic dye degradation efficiency is much higher than that of pure phase Bi 5 O 7 I, with excellent photocatalytic degradation performance of organic dyes, oxygen-vacancy-rich piezoelectric-photocatalysts are expected to be applied in sewage treatment and other fields.

[0008] Furthermore, deionized water is pure water that has been processed to remove most of the ions. It has very low conductivity and contains almost no dissolved solids and impurities. Using deionized water for washing can ensure that impurities and unreacted products on the surface of the product are effectively removed while avoiding the introduction of new ion contamination, thereby ensuring the purity and performance of the final product.

[0009] Furthermore, the amount of PEG 6000 used as a surfactant or template has an important influence on the morphology and size of the final product. Adjusting the amount of PEG 6000 within the scope of the present 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(NO 3 ) 3 •5H 2 O 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, and then affects the structure and properties of the product; Bi(NO 3 ) 3 •5H 2 The molar ratio of O and NaI is designed to ensure that the reaction proceeds completely to produce the target product BiOI.

[0010] Furthermore, by controlling the concentration of the NaI solution added and the Bi(NO 3 ) 3 •5H 2 The concentration of O indicates that the washing process not only removes excess impurities and unreacted products, but also ensures the washing efficiency, avoids product loss caused by excessive washing, and also helps to maintain the purity and stability of the product.

[0011] Furthermore, precise control of drying conditions helps maintain the sphericity and pore structure of the microspheres, which can increase the surface area and number of reactive sites of the catalyst, ensuring a high-purity BiOI precursor and reducing impurity interference in subsequent steps.

[0012] Furthermore, by controlling appropriate calcination conditions, it helps to promote the crystallization process of the product and improve the phase purity of the product, thereby enhancing its stability and catalytic activity.

[0013] Furthermore, the BiOI precursor, as a stable intermediate product, is conducive to the expected chemical reaction during the calcination process and is converted into the target product oxygen-rich vacancy Bi 5 O 7 I.

[0014] Furthermore, 5 O 7 As a catalyst, the unique crystal structure and chemical composition of I powder give it excellent catalytic performance, higher light absorption efficiency and stronger charge separation ability; 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 the catalytic efficiency.

[0015] The present invention also provides an oxygen-rich vacancy Bi 5 O 7 I microsphere piezoelectric-photocatalyst, based on the above-mentioned oxygen-rich Bi 5 O 7 The preparation method of I microsphere piezoelectric-photocatalyst is obtained, and the introduction of oxygen vacancies can significantly improve Bi 5 O 7 I has a strong light absorption capacity, especially in the visible light region. Oxygen vacancies act as electron traps and can capture photogenerated electrons, thereby extending the lifetime of photogenerated electrons and holes and reducing their recombination rate, which is beneficial to the redox reaction in the photocatalytic reaction, thereby improving the photocatalytic efficiency. 5 O 7 I microsphere piezoelectric-photocatalyst has a broad spectrum of degradation capabilities for a variety of pollutants. Due to its stable structure and composition, it can still maintain a high catalytic activity after repeated use and has good cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Bi modified with different amounts of PEG 6000 5 O 7 XRD pattern of I piezoelectric-photocatalyst; (a) Bi 5 O 7 I; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 in a molar ratio of 1:0.01 5 O 7 I; (c) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I; (d) is Bi(NO3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.03 5 O 7 I; Figure 2 Bi modified with different amounts of PEG 6000 5 O 7 UV-visible diffuse reflectance absorption spectrum of I piezoelectric-photocatalyst; (a) Bi 5 O 7 I; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 in a molar ratio of 1:0.01 5 O 7 I; (c) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I; (d) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.03 5 O 7 I; Figure 3 for Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 Scanning image of I piezoelectric-photocatalyst; (a) is Bi 5 O 7 I is the scanning image of piezoelectric-photocatalyst; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I Scanning image of piezoelectric-photocatalyst; Figure 4 for Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I Electron spin resonance spectrum; Figure 5 Bi modified with different amounts of PEG 6000 5 O 7 I Visible light catalytic degradation curve of organic dye Rhodamine B by piezoelectric-photocatalyst; (a) Bi 5 O 7 I; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 in a molar ratio of 1:0.01 5 O 7 I; (c) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I; (d) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.03 5 O 7 I; Figure 6 Bi modified with different amounts of PEG 6000 5 O 7 I Piezoelectric-photocatalyst piezoelectric catalytic degradation curve of organic dye Rhodamine B; (a) Bi 5 O 7 I; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 in a molar ratio of 1:0.01 5 O 7 I; (c) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I; (d) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.03 5 O 7 I; Figure 7 Bi modified with different amounts of PEG 60005 O 7 I Piezoelectric-photocatalyst light-pressure synergistic catalytic degradation curve of organic dye Rhodamine B; (a) is Bi 5 O 7 I; (b) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 in a molar ratio of 1:0.01 5 O 7 I; (c) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I; (d) is Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.03 5 O 7 I; Figure 8 Bi modified with different amounts of PEG 6000 5 O 7 I Comparison of RhB degradation efficiency of piezoelectric-photocatalyst under different catalytic conditions; Fig. 9 for Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I. Comparison of energy band structures and schematic diagram of catalytic degradation mechanism. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it. In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0018] The present invention provides an oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Change Bi(NO 3 ) 3 •5H 2 O and PEG 6000 powders were mixed, then dissolved in anhydrous ethanol, stirred for 5 min, and then 0.3 mol / L NaI solution was added dropwise, stirred again for 1.5-2 h, washed with deionized water, and dried at 60-80 °C for 8-12 h to obtain the precursor BiOI; Preferably, Bi(NO 3 ) 3 •5H 2 The molar ratio of O, PEG 6000, anhydrous ethanol, NaI and deionized water is 1:(0.01-0.03):180.89:1:185.03; Preferably, after washing, the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L; (2) The precursor BiOI was calcined at 500 °C for 2 h to obtain BiOI with oxygen vacancies. 5 O 7 I powder, namely oxygen-rich vacancy Bi 5 O 7 I Microsphere piezoelectric-photocatalyst.

[0019] Comparative Example 1: Bi was prepared by a two-step method 5 O 7 I, the specific steps are as follows: (1) Weigh 1.455 g Bi(NO 3 ) 3 •5H2 O was dissolved in 25 mL of alcohol, and 0.446 g of NaI was dissolved in 10 mL of deionized water, and each was stirred for 5 min; (2) Add NaI solution dropwise into Bi(NO 3 ) 3 •5H 2 O solution and continued stirring for 1.5 h; (3) Centrifuging, washing, and drying in sequence to obtain BiOI; (4) The BiOI powder was placed in a crucible and calcined at 500 °C for 2 h to obtain Bi 5 O 7 I powder.

[0020] Embodiment 1: The present invention provides an oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Add 3 mmol Bi(NO 3 ) 3 •5H 2 O was mixed with 0.03 mmol PEG 6000 powder, then dissolved in 25 mL anhydrous ethanol, stirred for 5 min, and then 10 mL aqueous solution of 3 mmol NaI was added dropwise, stirred again for 1.5 h, and then centrifuged and washed with 30 mL deionized water, and dried in a drying oven at 60 °C for 12 h to obtain the precursor BiOI; Preferably, after washing, the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L; (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain BiOI with oxygen vacancies. 5 O 7 I powder, namely oxygen-rich vacancy Bi 5 O 7 I Microsphere piezoelectric-photocatalyst.

[0021] Embodiment 2: The present invention provides an oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Add 3 mmol Bi(NO 3 ) 3 •5H 2O was mixed with 0.06 mmol PEG 6000 powder, then dissolved in 25 mL anhydrous ethanol, stirred for 5 min, and then 10 mL aqueous solution of 3 mmol NaI was added dropwise, stirred again for 1.5 h, and then centrifuged and washed with 30 mL deionized water, and dried in a drying oven at 60 °C for 12 h to obtain the precursor BiOI; Preferably, after washing, the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L; (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain BiOI with oxygen vacancies. 5 O 7 I powder, namely oxygen-rich vacancy Bi 5 O 7 I Microsphere piezoelectric-photocatalyst.

[0022] like Figure 3 As shown, Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I Scanning image of piezoelectric-photocatalyst, which demonstrates the two-step preparation of Bi 5 O 7 I is a 3D nanosphere morphology, and the addition of PEG 6000 does not change the Bi 5 O 7 3D nanosphere morphology of I.

[0023] like Figure 4 As shown, it reflects Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 The oxygen vacancy signal of I was detected by Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I obviously has a stronger signal, indicating that there are more oxygen vacancies in its lattice, indicating that it can capture more electrons and promote the separation of electrons and holes, ultimately improving the catalytic performance.

[0024] like Fig. 9 As shown, it reflects Bi 5 O 7 I and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 The degradation mechanism of dyes by I is that the electrons and holes generated in the catalytic process will be transferred to the conduction band and the valence band respectively. 2 The reaction produces superoxide radicals, which eventually react with the dye to produce CO 2 and H 2 O, while holes will directly react with the dye in the valence band to produce CO 2 and H 2 O.

[0025] Embodiment 3: The present invention provides an oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Add 3 mmol Bi(NO 3 ) 3 •5H 2 O was mixed with 0.09 mmol PEG 6000 powder, then dissolved in 25 mL anhydrous ethanol, stirred for 5 min, and then 10 mL aqueous solution of 3 mmol NaI was added dropwise, stirred again for 1.5 h, and then centrifuged and washed with 30 mL deionized water, and dried in a drying oven at 60 °C for 12 h to obtain the precursor BiOI; Preferably, after washing, the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L; (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain BiOI with oxygen vacancies. 5 O 7 I powder, namely oxygen-rich vacancy Bi 5 O 7 I Microsphere piezoelectric-photocatalyst.

[0026] like Figure 1 As shown in the figure, as PEG 6000 and Bi(NO 3 ) 3 •5H 2With the gradual increase of the molar ratio of PEG6000 to PEG-Bi 5 O 7 The mass fraction of I in the photocatalyst increases accordingly, and no new diffraction peaks are found in the figure, which proves that the Bi modified by PEG 6000 5 O 7 I Successful preparation of photocatalyst.

[0027] like Figure 2 As shown in Figure 2, it is proved that with the increase of PEG 6000 mass fraction, Bi 5 O 7 The visible light absorption capacity of the piezoelectric-photocatalyst was significantly improved, and Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I has the largest light absorption range.

[0028] like Figure 5 , Figure 6 and Figure 7 As shown in the figure, the degradation of organic dye Rhodamine B (RhB) under visible light, ultrasound and the combined action of the two revealed that Bi(NO 3 ) 3 •5H 2 The molar ratio of O and PEG 6000 is 1: (0.01~0.03) modified Bi 5 O 7 I piezoelectric-photocatalysts all performed better than Bi 5 O 7 I visible light degradation efficiency, piezoelectric degradation efficiency and light-pressure synergistic degradation efficiency, among which Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I has the best photocatalytic degradation performance, piezoelectric catalytic performance and photo-pressure synergistic catalytic performance.

[0029] like Figure 8 As shown in the figure, the degradation rate of RhB was calculated by kinetic simulation and the degradation rates of different samples under different catalytic conditions were obtained. It can be found that Bi(NO 3 ) 3 •5H 2 Bi modified with O and PEG 6000 at a molar ratio of 1:0.02 5 O 7 I photocatalytic degradation rate of RhB is Bi 5 O7 I, the degradation efficiency of piezoelectric catalysis RhB is 6.78 times that of Bi 5 O 7 I, and the degradation efficiency of RhB catalyzed by light pressure is 1.88 times that of Bi 5 O 7 I is 1.65 times that of PEG 6000, which is attributed to the addition of Bi 5 O 7 I brings more abundant oxygen vacancies.

[0030] Embodiment 4: The present invention provides an oxygen-rich vacancy Bi 5 O 7 I. A method for preparing a microsphere piezoelectric-photocatalyst, comprising the following steps: (1) Add 3 mmol Bi(NO 3 ) 3 •5H 2 O was mixed with 0.09 mmol PEG 6000 powder, then dissolved in 25 mL anhydrous ethanol, stirred for 5 min, and then 10 mL aqueous solution of 3 mmol NaI was added dropwise, stirred for another 2 h, and then centrifuged and washed with 30 mL deionized water, and dried in a drying oven at 80 °C for 8 h to obtain the precursor BiOI; Preferably, after washing, the Bi(NO 3 ) 3 •5H 2 The concentration of O is 0.12 mol / L, and the concentration of NaI is 0.3 mol / L; (2) The precursor BiOI was placed in a crucible and calcined at 500 °C for 2 h to obtain BiOI with oxygen vacancies. 5 O 7 I powder, namely oxygen-rich vacancy Bi 5 O 7 I Microsphere piezoelectric-photocatalyst.

[0031] In summary, in Bi 5 O 7 In the preparation process of I, the introduction of oxygen vacancies by adding PEG 6000 to improve its catalytic efficiency is a key step in developing efficient Bi 5 O 7 I An effective strategy for piezoelectric-photocatalysts. On the one hand, the modification of Bi by PEG 6000 can enhance the 5 O 7 I strong absorption of visible light, broadening the spectral absorption range of the catalyst, on the other hand, the addition of PEG 6000 5 O 7I brings abundant oxygen vacancies, which can act as electron traps to capture electrons. After the electrons are captured, the electronegativity in the material decreases, which accelerates the separation of electrons and holes, thereby achieving effective separation of electrons and holes and inhibiting electron-hole recombination. At the same time, it also increases the number of carriers and improves the catalytic efficiency.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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. A method for preparing oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, characterized in that: The following steps are involved: S1, Bi(NO3)3•5H2O and PEG 6000 powders are mixed, then dissolved in anhydrous ethanol, stirred evenly, and then NaI solution is dropped into the mixture, stirred evenly again, and then washed and dried in sequence to obtain a dry product; S2, calcining the dried product to obtain oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst.

2. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: Deionized water is used for washing in S1.

3. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 2, characterized in that: The molar ratio of Bi(NO3)3•5H2O, PEG 6000, anhydrous ethanol, NaI and deionized water in the S1 is 1:(0.01-0.03):180.89:1:185.

03.

4. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: The concentration of the NaI solution dripped into the S1 is 0.3 mol / L; the concentration of Bi(NO3)3•5H2O in the solution after washing is 0.12 mol / L.

5. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: The S1 is dissolved in anhydrous ethanol and stirred for 5 min; the NaI solution is added dropwise and stirred again for 1.5-2 h.

6. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: In S1, the drying temperature is 60-80°C and the drying time is 8-12 hours.

7. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: The calcination temperature in S2 is 500°C and the calcination time is 2 h.

8. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: The dried product is a BiOI precursor.

9. The method for preparing the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst according to claim 1, characterized in that: The oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst obtained in S2 is oxygen vacancy-rich Bi5O7I powder.

10. An oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst, characterized in that: The invention is obtained based on the preparation method of the oxygen vacancy-rich Bi5O7I microsphere piezoelectric-photocatalyst described in any one of claims 1-9.

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