Bi / Bi2WO6 / WO3-x photocatalyst as well as preparation method and application thereof
The Bi/Bi2WO6/WO3-x heterojunction photocatalyst was prepared by a solvent thermal-annealing method, which solved the problem of rapid recombination of electron-hole pairs in the Bi2WO6 photocatalyst and achieved efficient visible light degradation of tetracycline.
Patent Information
- Application Number
- CN202510949391.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-09-30
AI Technical Summary
The problem of rapid recombination of electron-hole pairs in existing Bi2WO6 photocatalysts limits their application in photocatalytic reactions, and the modification effect of traditional methods is limited.
Bi/Bi2WO6/WO3-x heterojunction photocatalyst was prepared by a solvothermal-annealing method. By introducing oxygen vacancies into WO3-x and combining it with Bi2WO6, a ternary heterojunction was formed. The localized surface plasmon resonance effect was used to expand the light absorption range and promote carrier separation.
The degradation activity of Bi2WO6 photocatalyst under visible light was significantly improved, and the tetracycline degradation rate reached 79.17%.
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Figure CN120714616A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of photocatalytic materials and relates to a Bi / Bi2WO6 / WO 3-x Heterojunction photocatalyst, preparation method and application thereof. Technical Background
[0002] The current water environment faces severe challenges, with industrial wastewater discharge, misuse of medical antiviral drugs, and agricultural pesticide contamination constituting major pollution sources. Improper handling of pharmaceutical products used in human and veterinary medicine, such as tetracycline (TC), can enter aquatic environments. This can induce the emergence of antibiotic-resistant bacteria and disrupt the microbial balance in ecosystems. These emerging pollutants in water systems have widespread impacts on the environment, organisms, and human health. Therefore, developing effective removal and remediation methods is crucial for protecting water resources.
[0003] Semiconductor-based photocatalytic technology can effectively utilize solar energy and is a promising green environmental technology. As a typical Aurivillius-type layered compound, the bismuth-based semiconductor Bi2WO6 consists of [Bi2O2] 2+ layer and perovskite layer [WO4] 2- Bi2WO6 is an alternating stacking structure that has been widely studied as a potential visible-light-driven semiconductor catalyst for photocatalytic pollutant degradation due to its advantages such as photostability, low cost, narrow band gap, and environmental friendliness. However, the rapid recombination of electron-hole pairs severely limits its application in photocatalytic reactions. To address these issues, strategies such as heterostructure construction, noble metal deposition, and ion doping have been widely used to modify bismuth tungstate. Constructing an S-type heterojunction is an effective strategy to improve the intrinsic Bi2WO6 photocatalytic efficiency. The S-type heterojunction can retain the highest redox potential in the system and achieve effective separation of electrons and holes.
[0004] Tungsten oxide (WO3) is a typical n-type semiconductor with the characteristics of high stability, non-toxicity, low cost and easy synthesis. Due to its photoelectric properties and high electron mobility, it has been widely used in the preparation of S heterojunction photocatalysts. In addition, the introduction of appropriate oxygen vacancies can adjust the electronic structure of WO3, expressed as WO 3-x The abundant oxygen vacancies on the surface make it also exhibit strong localized surface plasmon resonance (LSPR) capability. Therefore, it is considered to be one of the ideal candidate photocatalysts for full-spectrum driving of catalytic reactions.
[0005] Based on the above, the present invention proposes Bi / Bi2WO6 / WO 3-x Heterojunction photocatalysts, preparation methods, and applications thereof effectively extend the absorption range of visible light and improve degradation activity under visible light. Summary of the Invention
[0006] In order to solve the above technical problems, the present invention provides a Bi / Bi2WO6 / WO 3-x Heterojunction photocatalyst and its preparation method and application. Solvent thermal-annealing method is used to make WO 3-x Oxygen vacancies were generated in the solution, and Bi / Bi2WO6 / WO was prepared by a simple solvothermal method. 3-x Ternary heterojunction photocatalyst.
[0007] One of the purposes of the present invention is to provide a Bi / Bi2WO6 / WO 3-x Preparation method of heterojunction photocatalyst;
[0008] The second object of the present invention is to provide Bi / Bi2WO6 / WO prepared by the preparation method 3-x Heterojunction photocatalysts;
[0009] The third object of the present invention is to provide the Bi / Bi2WO6 / WO 3-x Application of heterojunction photocatalysts in tetracycline degradation.
[0010] The present invention provides a Bi / Bi2WO6 / WO 3-x The preparation method of the heterojunction photocatalyst comprises the following steps:
[0011] (1) Sodium tungstate dihydrate was dispersed in deionized water, hydrochloric acid was added and stirred until uniformly mixed, and then transferred to a Teflon-lined autoclave for hydrothermal reaction to obtain WO3. Next, WO3 was dispersed in anhydrous ethanol, stirred uniformly, and transferred to a magnetic boat, placed in a vacuum tube furnace for annealing, and cooled naturally to obtain WO 3-x ;
[0012] (2) Disperse bismuth nitrate pentahydrate, PVP and sodium tungstate dihydrate in a mixed solution of DMF and EG, and then add the pre-prepared WO 2 solution to the mixed solution in a certain molar ratio. 3-x The powder was dispersed uniformly by ultrasonication. The suspension was then transferred to an autoclave for solvent thermal reaction to obtain Bi / Bi2WO6 / WO 3-x Photocatalyst.
[0013] Preferably, when preparing WO3 in step (1), the amount of sodium tungstate dihydrate used is 0.32 g; the concentration of hydrochloric acid is 40%, the volume is 10 mL; the hydrothermal reaction temperature is 150-180°C, and the reaction time is 8-16 h.
[0014] Preferably, the step (1) prepares WO 3-xThe amount of anhydrous ethanol used is 5-20 mL, the annealing temperature in the vacuum tube furnace is controlled at 300-400°C, the annealing time is controlled at 2-4 h, and the heating rate is 5°C / min.
[0015] Preferably, the step (2) prepares Bi / Bi2WO6 / WO 3-x When the amount of bismuth nitrate pentahydrate is 0.97 g, the amount of PVP is 0.1 g, and the amount of sodium tungstate dihydrate is 0.33 g.
[0016] Preferably, the step (2) prepares Bi / Bi2WO6 / WO 3-x When the total volume of the mixed solution of DMF and EG is controlled to be 30 mL, the volume ratio of DMF to EG is 1: (0-4).
[0017] Preferably, the step (2) prepares Bi / Bi2WO6 / WO 3-x When the molar ratio of W:Bi is 1:(1~10).
[0018] The present invention also provides a Bi / Bi2WO6 / WO prepared by the above preparation method. 3-x Heterojunction photocatalyst.
[0019] The Bi / Bi2WO6 / WO provided by the present invention 3-x Application of heterojunction photocatalysts in photocatalytic degradation of tetracycline.
[0020] Beneficial effects:
[0021] The present invention also provides Bi / Bi2WO6 / WO 3-x Preparation method of heterojunction photocatalyst, using solvent thermal method combined with annealing to synthesize WO 3-x , with WO 3-x As a precursor, in WO 3-x Bi and Bi2WO6 were grown in situ on the surface to construct Bi / Bi2WO6 / WO 3-x Heterojunction photocatalyst. Metal Bi and WO 3-x The localized surface plasmon resonance effect extends the material's light absorption and enhances the absorption intensity in the visible light range. Bi2WO6 and WO 3-x The formed heterojunction drives the directional migration of carriers through the built-in electric field of the interface. 3-x The heterojunction photocatalyst showed excellent activity in photocatalytic degradation of tetracycline under visible light. After 80 min of visible light irradiation, Bi / Bi2WO6 / WO 3-x The degradation rate of TC by the ternary composite material reached 79.17%.
[0022] The preparation method of the present invention is simple, Bi / Bi2WO6 / WO3-x The construction of the ternary composite structure can be successfully used in the field of photocatalytic degradation. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 5Bi / BWO / WO in Example 1 of the present invention, 2Bi / BWO / WO, 7Bi / BWO / WO, Bi / BWO, BWO / WO, BWO and WO prepared in Comparative Examples 1-6 respectively 3-x XRD pattern of .
[0024] Figure 2 5Bi / BWO / WO in Example 1 of the present invention, Bi / BWO, BWO and WO prepared in Comparative Examples 3, 5 and 6 respectively 3-x SEM image of .
[0025] Figure 3 5Bi / BWO / WO in Example 1 of the present invention, 2Bi / BWO / WO, 7Bi / BWO / WO, Bi / BWO, BWO / WO, BWO and WO prepared in Comparative Examples 1-6 respectively 3-x UV-visible diffuse reflectance spectrum.
[0026] Figure 4 5Bi / BWO / WO in Example 1 of the present invention, 2Bi / BWO / WO, 7Bi / BWO / WO, Bi / BWO, BWO / WO, BWO and WO prepared in Comparative Examples 1-6 respectively 3-x Transient photocurrent response spectrum, electrochemical impedance spectroscopy and photoluminescence spectrum.
[0027] Figure 5 5Bi / BWO / WO in Example 1 of the present invention, 2Bi / BWO / WO, 7Bi / BWO / WO, Bi / BWO, BWO / WO, BWO and WO prepared in Comparative Examples 1-6 respectively 3-x Efficiency diagram and first-order kinetic fitting diagram of tetracycline degradation under visible light.
[0028] Figure 6 The cyclic degradation diagram of 5Bi / BWO / WO in Example 1 of the present invention and the XRD comparison diagram before and after the reaction. DETAILED DESCRIPTION
[0029] To facilitate those skilled in the art to implement the technical solution of the present invention, the following is described in conjunction with specific examples and drawings. It should be noted that the described embodiments are only some examples, not all implementation plans. Unless otherwise stated, the reagents involved in the examples are all commercially available products, and the experimental methods all adopt conventional technical means in this area. It should be noted that the examples described herein are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection thereof.
[0030] The following is further described through specific examples.
[0031] Example 1
[0032] A Bi / Bi2WO6 / WO 3-x A heterojunction photocatalyst and a preparation method thereof, comprising the following steps:
[0033] (1)WO 3-x Preparation: 0.32 g of sodium tungstate dihydrate was dispersed in 20 mL of deionized water, and then hydrochloric acid (40% HCl, 10 mL) was added to the sodium tungstate solution at room temperature and stirred to mix the solution thoroughly. Then, the mixed solution was transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180°C for 12 hours, and then naturally cooled to room temperature. The sample WO3 was obtained by centrifuging the mixture, washing it several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12 hours. The prepared WO3 powder (0.5 g) was dispersed in 15 mL of anhydrous ethanol to form a suspension. After vigorous stirring for 10 minutes, the suspension was poured into a magnetic boat and transferred to a vacuum tube furnace. The initial temperature was set to 25°C, and the temperature was increased at a rate of 5°C / min until the temperature reached 350°C, and annealed at 350°C for 3 hours, and naturally cooled to room temperature to obtain the sample WO 3-x .
[0034] (2)Bi / Bi2WO6 / WO 3-x Preparation of heterojunction photocatalyst: 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of DMF and EG mixed solution (DMF and EG volume ratio was 1:1) under magnetic stirring and ultrasonic treatment. 3-x The powder was added to the above mixed solution at a molar ratio of W:Bi = 1:5 and ultrasonically dispersed for 30 minutes. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 hours. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 hours. The product is labeled 5Bi / BWO / WO.
[0035] Comparative Example 1
[0036] A Bi / Bi2WO6 / WO 3-x A heterojunction photocatalyst and a preparation method thereof, comprising the following steps:
[0037] (1)WO 3-x Preparation: 0.32 g of sodium tungstate dihydrate was dispersed in 20 mL of deionized water, and then hydrochloric acid (40% HCl, 10 mL) was added to the sodium tungstate solution at room temperature and stirred to mix the solution thoroughly. Then, the mixed solution was transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180°C for 12 hours, and then naturally cooled to room temperature. The sample WO3 was obtained by centrifuging the mixture, washing it several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12 hours. The prepared WO3 powder (0.5 g) was dispersed in 15 mL of anhydrous ethanol to form a suspension. After vigorous stirring for 10 minutes, the suspension was poured into a magnetic boat and transferred to a vacuum tube furnace. The initial temperature was set to 25°C, and the temperature was increased at a rate of 5°C / min until the temperature reached 350°C, and annealed at 350°C for 3 hours, and naturally cooled to room temperature to obtain the sample WO 3-x .
[0038] (2)Bi / Bi2WO6 / WO 3-x Preparation of heterojunction photocatalyst: 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of DMF and EG mixed solution (DMF and EG volume ratio was 1:1) under magnetic stirring and ultrasonic treatment. 3-x The powder was added to the above mixed solution at a molar ratio of W:Bi = 1:2 and ultrasonically dispersed for 30 minutes. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 hours. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 hours. The product is labeled 2Bi / BWO / WO.
[0039] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the molar ratio of W:Bi in step (2) is controlled to be 1:2.
[0040] Comparative Example 2
[0041] A Bi / Bi2WO6 / WO 3-x A heterojunction photocatalyst and a preparation method thereof, comprising the following steps:
[0042] (1)WO 3-xPreparation: 0.32 g of sodium tungstate dihydrate was dispersed in 20 mL of deionized water, and then hydrochloric acid (40% HCl, 10 mL) was added to the sodium tungstate solution at room temperature and stirred to mix the solution thoroughly. Then, the mixed solution was transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180°C for 12 hours, and then naturally cooled to room temperature. The sample WO3 was obtained by centrifuging the mixture, washing it several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12 hours. The prepared WO3 powder (0.5 g) was dispersed in 15 mL of anhydrous ethanol to form a suspension. After vigorous stirring for 10 minutes, the suspension was poured into a magnetic boat and transferred to a vacuum tube furnace. The initial temperature was set to 25°C, and the temperature was increased at a rate of 5°C / min until the temperature reached 350°C, and annealed at 350°C for 3 hours, and naturally cooled to room temperature to obtain the sample WO 3-x .
[0043] (2)Bi / Bi2WO6 / WO 3-x Preparation of heterojunction photocatalyst: 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of DMF and EG mixed solution (DMF and EG volume ratio was 1:1) under magnetic stirring and ultrasonic treatment. 3-x The powder was added to the above mixed solution at a molar ratio of W:Bi = 1:7 and ultrasonically dispersed for 30 minutes. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 hours. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 hours. The product is labeled 7Bi / BWO / WO.
[0044] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the molar ratio of W:Bi in step (2) is controlled to be 1:7.
[0045] Comparative Example 3
[0046] This comparative example provides a method for preparing Bi / BWO, comprising the following steps:
[0047] 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP, and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of a DMF / EG mixture (1:1 volume ratio) under magnetic stirring and ultrasonic treatment. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 h. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 h. The product is labeled Bi / BWO.
[0048] The difference between Comparative Example 3 and Example 1 is that WO is not added in the control step (2) of Comparative Example 3. 3-x , Bi / BWO was prepared.
[0049] Comparative Example 4
[0050] This comparative example provides a method for preparing BWO / WO, comprising the following steps:
[0051] (1)WO 3-x Preparation: 0.32 g of sodium tungstate dihydrate was dispersed in 20 mL of deionized water, and then hydrochloric acid (40% HCl, 10 mL) was added to the sodium tungstate solution at room temperature and stirred to mix the solution thoroughly. Then, the mixed solution was transferred to a 50 mL Teflon-lined stainless steel autoclave. The autoclave was sealed and heated at 180°C for 12 hours, and then naturally cooled to room temperature. The sample WO3 was obtained by centrifuging the mixture, washing it several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12 hours. The prepared WO3 powder (0.5 g) was dispersed in 15 mL of anhydrous ethanol to form a suspension. After vigorous stirring for 10 minutes, the suspension was poured into a magnetic boat and transferred to a vacuum tube furnace. The initial temperature was set to 25°C, and the temperature was increased at a rate of 5°C / min until the temperature reached 350°C, and annealed at 350°C for 3 hours, and naturally cooled to room temperature to obtain the sample WO 3-x .
[0052] (2) Preparation of BWO / WO heterojunction photocatalyst: 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of deionized water under magnetic stirring and ultrasonic treatment. 3-x The powder was added to the above mixed solution at a molar ratio of W:Bi = 1:5 and ultrasonically dispersed for 30 minutes. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 hours. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 hours. The product is labeled BWO / WO.
[0053] The difference between Comparative Example 4 and Example 1 is that in the control step (2) of Comparative Example 4, the solvent is replaced with deionized water to prepare BWO / WO.
[0054] Comparative Example 5
[0055] This comparative example provides a method for preparing Bi2WO6, comprising the following steps:
[0056] 0.97 g of bismuth nitrate pentahydrate, 0.1 g of PVP, and 0.33 g of sodium tungstate dihydrate were dispersed in 30 mL of deionized water under magnetic stirring and ultrasonic treatment. The suspension was transferred to a 50 mL Teflon-lined autoclave and heated at 180°C for 24 h. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven at 60°C for 12 h to obtain monomeric Bi2WO6, labeled as BWO.
[0057] The difference between Comparative Example 5 and Example 1 is that WO is not added in the control step (2) of Comparative Example 5. 3-x The solvent was replaced with deionized water, and only Bi2WO6 was prepared.
[0058] Comparative Example 6
[0059] This comparative example provides a WO 3-x The preparation method comprises the following steps:
[0060] 0.32g of sodium tungstate dihydrate was dispersed in 20mL of deionized water, and then hydrochloric acid (40% HCl, 10mL) was added to the sodium tungstate solution at room temperature and stirred to mix the solution thoroughly. Then, the mixed solution was transferred to a 50mL stainless steel autoclave lined with Teflon. The autoclave was sealed and heated at 180°C for 12h, and then naturally cooled to room temperature. The sample WO3 was obtained by centrifuging the mixture, washing it several times with deionized water and anhydrous ethanol, and drying it at 60°C for 12h. The prepared WO3 powder (0.5g) was dispersed in 15mL of anhydrous ethanol to form a suspension. After vigorous stirring for 10min, the suspension was poured into a magnetic boat and transferred to a vacuum tube furnace. The initial temperature was set to 25°C, and the temperature was increased at a rate of 5°C / min until the temperature reached 350°C, and annealed at 350°C for 3 hours, and naturally cooled to room temperature to obtain the sample WO 3-x .
[0061] The difference between Comparative Example 6 and Example 1 is that only WO 3-x .
[0062] The photocatalyst Bi / Bi2WO6 / WO of the present invention 3-x Characterization:
[0063] The phase structure of the material was characterized by X-ray diffraction technique. Scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy were used to characterize the Bi / Bi2WO6 / WO 3-x The microstructure, lattice fringes, and element distribution of the composite were investigated. Transient photocurrent measurements and electrochemical impedance spectroscopy were performed using an electrochemical workstation. UV-visible diffuse reflectance spectroscopy was used to characterize the photoresponse characteristics.
[0064] The photocatalyst Bi / Bi2WO6 / WO of the present invention 3-x Photocatalytic experiments:
[0065] The catalyst was weighed into a test tube containing a tetracycline (TC) solution. The catalyst-contaminated solution was stirred in the dark for 30 minutes to allow the catalyst and contaminant molecules to mix and contact thoroughly, achieving adsorption-desorption equilibrium. A 300W xenon lamp was used as the visible light source, and a water circulation system was used to control the temperature of the reactant solution during irradiation. 2 mL of the reaction solution was collected every 20 minutes during the reaction. The suspension was centrifuged and the supernatant was collected. The contaminant concentration was measured using a UV spectrophotometer.
Claims
1. A Bi / Bi2WO6 / WO 3-x Photocatalyst and its preparation method and application, characterized in that, The following steps are involved: (1) Sodium tungstate dihydrate was dissolved in deionized water, hydrochloric acid was added and stirred to mix evenly, and then transferred to a Teflon-lined autoclave for hydrothermal reaction. After cooling, centrifugation was performed and dried to obtain WO3. WO3 was dispersed in anhydrous ethanol, stirred and transferred to a magnetic boat, annealed in a vacuum tube furnace, and naturally cooled to obtain WO 3-x ; (2) Bismuth nitrate pentahydrate, PVP and sodium tungstate dihydrate were dispersed in a mixed solution of DMF and EG under magnetic stirring and ultrasonic treatment. 3-x The powder was added to the above mixed solution in a certain molar ratio and ultrasonically dispersed and mixed evenly. The suspension was transferred to an autoclave for solvothermal reaction. The resulting precipitate was collected by centrifugation and washed several times with deionized water and ethanol. Finally, the resulting powder was dried in an oven to obtain Bi / Bi2WO6 / WO 3-x photocatalyst.
2. Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: When preparing WO3 in step (1), the amount of sodium tungstate dihydrate used is 0.32 g; the concentration of hydrochloric acid is 40%, and the volume is 10 mL; the hydrothermal reaction temperature is 150-180° C., and the reaction time is 8-16 h.
3. Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: The step (1) prepares WO 3-x The amount of anhydrous ethanol used is 5-20 mL, the annealing temperature in the vacuum tube furnace is controlled to be 300-400° C., the annealing time is controlled to be 2-4 h, and the heating rate is 5° C. / min.
4. Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: In the step (2), the amount of bismuth nitrate pentahydrate used is 0.97 g, the amount of PVP used is 0.1 g, and the amount of sodium tungstate dihydrate used is 0.33 g.
5. Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: The total volume of the mixed solution of DMF and EG in step (2) is controlled to be 30 mL, and the volume ratio of DMF to EG is 1: (0-4).
6. Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: The molar ratio of W:Bi in step (2) is 1:(1-10).
7. The Bi / Bi2WO6 / WO according to claim 1 3-x The method for preparing a heterojunction photocatalyst is characterized in that: The solvent thermal reaction temperature in step (2) is 120-200° C., and the heating time is 12-24 hours.
8. Bi / Bi2WO6 / WO prepared by the method according to any one of claims 1 to 7 3-x Heterojunction photocatalyst.
9. A Bi / Bi2WO6 / WO as claimed in claim 8 3-x The application of heterojunction photocatalyst in the field of photocatalysis is characterized by: The Bi / Bi2WO6 / WO 3-x Application of heterojunction photocatalysts in photocatalytic degradation of tetracycline.