Preparation method and application of bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst

Abstract

The application relates to the technical field of photocatalysts, in particular to a preparation method and application of a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst. The method comprises the following steps: S1, preparing BiOIO3 powder; S2, preparing a BiOIO3 / Bi2WO6 heterojunction photocatalyst; the BiOIO3 powder obtained in the step S1 is added into deionized water and uniformly ultrasonically treated, then Bi(NO3)3.5H2O, Na2WO4.2H2O and a surfactant are respectively added, stirring is uniformly carried out, a mixed solution is obtained, finally, the mixed solution is loaded into a reaction kettle, reaction is carried out at 120-130 DEG C for 18-30 hours, deionized water washing and drying are carried out, and the bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst is obtained. The bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst prepared by the application has excellent photocatalytic degradation performance, and the degradation rate of norfloxacin can reach 94.84% through photodegradation.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photocatalysts, in particular to a preparation method of a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst and application thereof. BACKGROUND

[0002] Antibiotics have been rapidly developed and applied due to their wide value in the fields of medicine and health, life sciences, etc. However, the misuse and abuse of antibiotics have also caused serious environmental pollution problems, especially serious damage to animals and plants in aquatic systems. Among antibiotics, norfloxacin is one of the most widely used quinolone drugs. In the past few decades, norfloxacin has been widely used and, due to its structural stability, it has been retained in the environment system in large amounts, causing serious harm to human health and the ecological environment. At present, the methods for degrading norfloxacin mainly include chemical oxidation, photocatalysis, biological treatment and electrolysis. Among these methods, considering the factors of cost, efficiency and operability, photocatalytic oxidation is one of the most promising technologies for sustainable removal of norfloxacin pollution in water. Some traditional semiconductor photocatalysts, such as TiO2 and ZnO, have been used in the research and application of photocatalytic degradation of norfloxacin. However, due to the problems of high cost and low stability of the material, wide band gap, low light energy utilization rate, low charge separation capacity and the like, its wide application is limited. Therefore, it is necessary to develop new photocatalysts with high efficiency, stability and visible light activity.

[0003] Bismuth-based materials as a new type of semiconductor photocatalyst are widely used in the fields of photocatalytic degradation of organic pollutants, CO2 reduction, N2 reduction, removal of harmful gases and the like due to their diverse composition forms, unique crystal structure and low price. Common bismuth-based photocatalysts include Bi2WO6, BiOI, Bi2O3, Bi2MoO6, BiOBr, BIO and the like. In 2022, Gong et al. prepared Au / BiOCl heterojunction composite photocatalyst for CO reduction, and in 2018, He et al. synthesized a new type of Bi4MoO9 / Bi heterojunction photocatalyst for NO reduction by using oxygen vacancy defects. Bismuth-based photocatalytic materials have attracted more and more attention in the field of semiconductor photocatalysis due to their excellent photocatalytic performance.

[0004] BiOIO3 has excellent photocatalytic performance due to its non-centrosymmetric crystal structure, layered structure and internal polar field. BiOIO3 is composed of Aurivillius type (Bi2O2) 2+ layer and IO 3-The internal polarization electric field formed by the layered structure of the pyramid effectively inhibits the recombination of photo-generated electrons and holes. In addition, the Bi6s orbital can be hybridized with the O2p orbital to form a valence band (VB), which is conducive to the migration of photo-generated electrons and holes in the opposite direction. BiOIO3 has excellent photocatalytic performance due to its internal polarization electric field and hybrid structure, and plays an important role in CO2 reduction and pollutant degradation. However, pure BiOIO3 has a relatively wide band gap (about 3.0 eV), which can only be excited by ultraviolet light, resulting in weak visible light response. The high recombination rate of photo-generated carriers and the difficulty in regenerating the catalyst also limit the practical application of BiOIO3 as a semiconductor photocatalytic material. Bi2WO6 has attracted much attention due to its low cost, non-toxicity, adjustable morphology, and excellent optical and chemical properties. The valence band and conduction band of Bi2WO6 are composed of O2p and Bi6s orbitals as well as W5d and O2p orbitals, and the Aurivillius type is composed of (Bi2O2) 2+ and (WO4) 2- However, Bi2WO6 has a relatively small surface area, low quantum yield, and rapid recombination of photo-generated carriers, which seriously limits its development in the field of photocatalysis.

[0005] In order to overcome the narrow light absorption range and low carrier transport efficiency of single-phase semiconductor materials, new semiconductor photocatalysts need to be developed to overcome the above shortcomings. SUMMARY

[0006] To solve the above technical problems, the application provides a preparation method of a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst. In the BiOIO3 / Bi2WO6 heterojunction photocatalyst prepared by the application, the conduction band of Bi2WO6 is lower than that of BiOIO3, and the valence band of Bi2WO6 is lower than that of BiOIO3. During the photocatalytic reaction, electrons from the conduction band of BiOIO3 are conducted into the valence band of Bi2WO6, resulting in the formation of a heterojunction. The BiOIO3 / Bi2WO6 heterojunction interface can shorten the channel for electron transport, and the formation of the heterojunction enhances the oxidation ability of the BiOIO3 valence band holes and the reduction ability of the Bi2WO6 conduction band electrons, thereby improving the photocatalytic degradation efficiency of the organic substance norfloxacin.

[0007] In a first aspect, the application provides a preparation method of a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst, which adopts the following technical scheme:

[0008] A preparation method of a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst, comprising the following steps:

[0009] S1, preparation of BiOIO3: according to the molar ratio, Bi(NO3)3·5H2O is dissolved in deionized water, ultrasonic is uniform, Bi(NO3)3 solution is obtained, then KIO3 is added into Bi(NO3)3 solution, magnetic stirring is carried out for 30-60 min, a mixed solution is obtained; finally, the mixed solution is loaded into a reaction kettle, reaction is carried out at 145-155℃ for 4-6h, after cooling, deionized water is used for washing, drying is carried out, BiOIO3 powder is obtained, and is prepared for subsequent doping Bi2WO6.

[0010] S2, preparation of BiOIO3 / Bi2WO6 heterojunction photocatalyst: BiOIO3 powder obtained in step S1 is added into deionized water, ultrasonic is uniform, BiOIO3 mixed solution is obtained, then Bi(NO3)3·5H2O, Na2WO4·2H2O and a surfactant are added into the BiOIO3 mixed solution, stirring and mixing are carried out uniformly, a mixed solution is obtained, finally, the mixed solution is loaded into a reaction kettle, reaction is carried out at 120-130℃ for 18-30h, deionized water is used for washing and drying, and a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst is obtained.

[0011] By adopting the above technical scheme, in step S1, Bi(NO3)3 and KIO3 are reacted at 145-155℃ for 4-6h, after cooling, deionized water is used for washing, drying is carried out, and BiOIO3 powder is obtained, which is prepared for subsequent doping Bi2WO6; in step S2, the surfactant is coated and dispersed, Bi(NO3)3·5H2O and Na2WO4·2H2O are reacted on the surface of BiOIO3 crystal, and Bi2WO6 is generated, so that the BiOIO3 / Bi2WO6 heterojunction photocatalyst is obtained. The catalyst with excellent photocatalytic degradation performance is prepared in the application, the BiOIO3 / Bi2WO6 heterojunction can effectively separate photo-generated electrons and holes, and has strong oxidizing and reducing properties, so that the separation efficiency of photo-generated carriers is improved. In the process of photodegradation, the separated valence band electrons and holes respectively oxidize and degrade norfloxacin, and high-efficiency degradation capacity is realized.

[0012] Preferably, in step S1, the molar ratio of Bi(NO3)3·5H2O to deionized water is 1:4500, and the molar ratio of Bi(NO3)3·5H2O to KIO3 is 1:1.

[0013] Preferably, in step S1, the drying process conditions are as follows: drying is carried out at 60-80℃ for 1-3h.

[0014] Preferably, in step S2, the molar ratio of BiOIO3 powder to deionized water is 1:18.

[0015] Preferably, in step S2, the surfactant is one or two of oleylamine and cetyltrimethylammonium bromide.

[0016] Preferably, in step S2, the surfactant is a combination of oleylamine and cetyltrimethylammonium bromide in a mass ratio of 1:(5-8).

[0017] By adopting the technical scheme, the surfactant can form a thin film on the surface of BiOIO3 and Bi2WO6 particles, play a coating role, prevent the aggregation and agglomeration of the particles. At the same time, the surfactant also helps to make the reactants uniformly dispersed in the solution, avoiding the particles from depositing or gathering together. Oleylamine and cetyltrimethylammonium bromide are used as candidates for the surfactant, and are combined in a certain mass ratio. With the help of these surfactants, the dispersibility in the reaction process can be effectively improved, and the preparation effect of the bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst is further improved.

[0018] Preferably, in step S2, the molar ratio of Bi(NO3)3·5H2O, Na2WO4·2H2O and the surfactant is 2:1:(0.14-0.18).

[0019] Preferably, in step S2, the molar ratio of BiOIO3 to Bi2WO6 is 25:(40-90).

[0020] Preferably, in step S2, the drying process condition is 50-70℃ for 10-18h.

[0021] In the second aspect, the application provides an application of the bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst, which adopts the following technical scheme:

[0022] The application of the bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst prepared by the above-mentioned preparation method of the bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst in the photodegradation of organic matter norfloxacin.

[0023] In summary, the beneficial technical effects of the application are:

[0024] 1. The BiOIO3 / Bi2WO6 heterojunction photocatalyst prepared by the application has excellent photocatalytic degradation performance. Through the photodegradation of norfloxacin, the degradation rate can reach 94.84% in 90min of light reaction, and the degradation capacity is significantly better than that of pure BiOIO3 and pure Bi2WO6.

[0025] 2. BiOBiW-0.8 has a petal-like structure cross-linked by two different sizes of nanosheets, the specific surface area of the composite material is increased, the active sites are increased, the absorption of visible light is significantly enhanced, and the photocatalytic degradation efficiency is greatly improved.

[0026] 3. The formation of BiOIO3 / Bi2WO6 heterojunction successfully separates photo-generated electrons and holes, while retaining the strong oxidizing property of holes in the valence band of BiOIO3 and the strong reducing property of electrons in the conduction band of Bi2WO6, greatly improving the separation efficiency of photo-generated carriers. In the case of photodegradation, the valence band electrons separated in Bi2WO6 convert oxygen molecules into superoxide radicals, while the valence band holes separated in BiOIO3 convert water molecules into hydroxyl radicals, both of which effectively degrade norfloxacin.

[0027] 4. The preparation method of the present application has low cost, is green and environmentally friendly, and has little impact on the environment. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows:

[0029] Figure 1 SEM image of BiOBiW-0.8 prepared for Example 3;

[0030] Figure 2 EDS spectrum of BiOBiW-0.8 prepared for Example 3;

[0031] Figure 3 XRD pattern of the photocatalyst prepared for Examples 1-4 and Comparative Examples 1-2;

[0032] Figure 4 Photocatalytic degradation effect of norfloxacin by the photocatalyst prepared for Examples 1-4 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0033] The embodiments of the present application will be described in detail below with reference to the embodiments, but those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. If no specific conditions are specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagents or instruments used is specified, it is a conventional product that can be purchased on the market.

[0034] Example 1

[0035] A preparation method of a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst, comprising the following steps:

[0036] S1, preparation of BiOIO3: according to the molar ratio, 0.001 mol of Bi(NO3)3·5H2O was dissolved in 4.5 mol of deionized water, ultrasonic homogenization, Bi(NO3)3solution was obtained, then 0.001 mol of KIO3 was added to the Bi(NO3)3solution and magnetically stirred for 30 min to obtain a mixed solution; finally, the mixed solution was loaded into a reaction kettle, reacted at 145℃ for 6h, washed with deionized water after cooling, dried at 60℃ for 3h, and BiOIO3 powder was obtained, which was used for standby;

[0037] S2, preparation of BiOIO3 / Bi2WO6 heterojunction photocatalyst: 0.25 mol of BiOIO3 powder obtained in step S1 was added to 4.5 mol of deionized water, ultrasonic homogenization, BiOIO3 mixed solution was obtained, then 0.80 mol of Bi(NO3)3·5H2O, 0.40 mol of Na2WO4·2H2O and 0.056 mol of oleylamine were added to the BiOIO3 mixed solution, stirred and mixed uniformly to obtain a mixed solution, finally the mixed solution was loaded into a reaction kettle, reacted at 120℃ for 30h, washed with deionized water, dried at 50℃ for 18h, and a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst was obtained, named BiOBiW-0.4.

[0038] Example 2

[0039] A preparation method of a bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst, comprising the following steps:

[0040] S1, preparation of BiOIO3: according to the molar ratio, 0.001 mol of Bi(NO3)3·5H2O was dissolved in 4.5 mol of deionized water, ultrasonic homogenization, Bi(NO3)3solution was obtained, then 0.001 mol of KIO3 was added to the Bi(NO3)3solution and magnetically stirred for 60 min to obtain a mixed solution; finally, the mixed solution was loaded into a reaction kettle, reacted at 155℃ for 4h, washed with deionized water after cooling, dried at 80℃ for 1h, and BiOIO3 powder was obtained, which was used for standby;

[0041] S2, preparation of BiOIO3 / Bi2WO6 heterojunction photocatalyst: 0.25 mol of BiOIO3 powder obtained in step S1 was added to 4.5 mol of deionized water, and ultrasonic mixing was performed to obtain a BiOIO3 mixed solution. Next, 1.2 mol of Bi(NO3)3·5H2O, 0.60 mol of Na2WO4·2H2O and 0.10 mol of cetyltrimethylammonium bromide were added to the BiOIO3 mixed solution, and stirring and mixing were performed to obtain a mixed solution. Finally, the mixed solution was loaded into a reaction kettle, and reaction was performed at 130℃ for 18 hours. Deionized water was used for washing, and drying was performed at 70℃ for 18 hours to obtain a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst, which was named BiOBiW-0.6.

[0042] Example 3

[0043] A preparation method of a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst, comprising the following steps:

[0044] S1, preparation of BiOIO3: 0.001 mol of Bi(NO3)3·5H2O was dissolved in 4.5 mol of deionized water, and ultrasonic mixing was performed to obtain a Bi(NO3)3 solution. Then, 0.001 mol of KIO3 was added to the Bi(NO3)3 solution, and magnetic stirring was performed for 40 min to obtain a mixed solution. Finally, the mixed solution was loaded into a reaction kettle, and reaction was performed at 150℃ for 5 h. After cooling, deionized water was used for washing, and drying was performed at 70℃ for 2 h to obtain BiOIO3 powder, which was reserved for use.

[0045] S2, preparation of BiOIO3 / Bi2WO6 heterojunction photocatalyst: 0.25 mol of BiOIO3 powder obtained in step S1 was added to 4.5 mol of deionized water, and ultrasonic mixing was performed to obtain a BiOIO3 mixed solution. Next, 1.6 mol of Bi(NO3)3·5H2O, 0.80 mol of Na2WO4·2H2O and 0.12 mol of a surfactant were added to the BiOIO3 mixed solution, and stirring and mixing were performed to obtain a mixed solution. Finally, the mixed solution was loaded into a reaction kettle, and reaction was performed at 125℃ for 24 hours. Deionized water was used for washing, and drying was performed at 60℃ for 15 h to obtain a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst, which was named BiOBiW-0.8. The surfactant was a combination of oleylamine and cetyltrimethylammonium bromide in a mass ratio of 1:5.

[0046] Example 4

[0047] A preparation method of a bismuth tungstate-doped bismuth oxyiodate heterojunction photocatalyst, comprising the following steps:

[0048] S1, preparation of BiOIO3: according to the molar ratio, 0.001 mol of Bi(NO3)3·5H2O was dissolved in 4.5 mol of deionized water, ultrasonic homogenization, Bi(NO3)3solution was obtained, then 0.001 mol of KIO3 was added to the Bi(NO3)3solution and stirred magnetically for 40 min to obtain a mixed solution; finally, the mixed solution was loaded into a reaction kettle, reacted at 150°C for 5h, washed with deionized water after cooling, dried at 70°C for 2h, and BiOIO3 powder was obtained for standby;

[0049] S2, preparation of BiOIO3 / Bi2WO6 heterojunction photocatalyst: 0.25 mol of BiOIO3 powder obtained in step S1 was added to 4.5 mol of deionized water, ultrasonic homogenization, BiOIO3 mixed solution was obtained, then 1.8 mol of Bi(NO3)3·5H2O, 0.90 mol of Na2WO4·2H2O and 0.17 mol of surfactant were added to the BiOIO3 mixed solution respectively, stirred and mixed uniformly to obtain a mixed solution, finally the mixed solution was loaded into a reaction kettle, reacted at 125°C for 24h, washed with deionized water, dried at 60°C for 15h, and bismuth tungstate doped bismuth oxyiodate heterojunction photocatalyst was obtained, named BiOBiW-0.9. The surfactant is a combination of oleylamine and cetyltrimethylammonium bromide in a mass ratio of 1:8.

[0050] Comparative Example 1: preparation of BiOIO3:

[0051] According to the molar ratio, 0.001 mol of Bi(NO3)3·5H2O was dissolved in 4.5 mol of deionized water, ultrasonic homogenization, Bi(NO3)3solution was obtained, then 0.001 mol of KIO3 was added to the Bi(NO3)3solution and stirred magnetically for 40 min to obtain a mixed solution; finally, the mixed solution was loaded into a reaction kettle, reacted at 150°C for 5h, washed with deionized water after cooling, dried at 70°C for 2h, and BiOIO3 powder was obtained.

[0052] Comparative Example 2: preparation of Bi2WO6

[0053] 0.97g Bi(NO3)3·5H2O, 0.05g cetyltrimethylammonium bromide and 0.33g Na2WO4·2H2O were sequentially dissolved in 80mL deionized water, ultrasonic homogenization, a mixed solution was obtained, then the mixed solution was loaded into a reaction kettle, reacted at 120°C for 24h, washed with deionized water after cooling, dried at 70°C for 24h, and Bi2WO6 powder was obtained.

[0054] Characterization

[0055] Figure 1SEM image of BiOBiW-0.8 prepared in Example 3 was characterized by a Hitachi S-4700 field emission scanning electron microscope (SEM) with an operating voltage of 15 kV. From Figure 1 It can be seen that BiOBiW-0.8 is composed of irregular nanosheets, Bi2WO6 is uniformly dispersed between BiOIO3 nanosheets, and has a loose flower-like structure, which provides more active sites for the attachment of pollutants.

[0056] Figure 2 EDS spectrum of BiOBiW-0.8 prepared in Example 3 was analyzed by energy dispersive spectroscopy (EDS, Thermo Noran VANTAGE-ESI) for component analysis of BiOBiW-0.8. From Figure 2 It can be seen that the BiOBiW-0.8 composite catalyst mainly contains Bi, I, O, and W elements, among which the mass fraction of Bi element is the largest, followed by W, indicating that BiOIO3 and Bi2WO6 are successfully compounded.

[0057] Figure 3 XRD patterns of the photocatalysts prepared in Examples 1-4 and Comparative Examples 1-2 were analyzed by X-ray diffraction (XRD) on a Thermo ARL SCINTAG X'TRA X-ray diffractometer with Cu target Kα radiation (λ = 0.154 056 nm), tube voltage of 40 kV, tube current of 40 mA, and scanning range of 10-80°. From Figure 3 It can be seen that the characteristic diffraction peaks of the BiOIO3 / Bi2WO6 heterojunction photocatalysts prepared in Examples 1-4 are relatively sharp, indicating that the heterojunction photocatalysts have good crystallinity. The characteristic diffraction peaks of BiOIO3 prepared in Comparative Example 1 and Bi2WO6 prepared in Comparative Example 2 were analyzed and compared with standard cards PDF #75-0995 and JCPDS #73-2020, respectively. The diffraction peaks of the prepared BiOIO3 / Bi2WO6 are consistent with those of BiOIO3 and Bi2WO6, indicating that the BiOIO3 / Bi2WO6 heterojunction photocatalysts prepared in Examples 1-4 are truly present. The diffraction peak intensity of the BiOIO3 / Bi2WO6 heterojunction photocatalysts prepared in Examples 1-4 is different, which is due to the influence of ion doping on the crystallinity of the sample.

[0058] Performance test

[0059] The photocatalysts prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to photocatalytic degradation test on 10 mg / L norfloxacin.

[0060] Test method: The photodegradation reaction was carried out in a photochemical reactor, using a 500W xenon lamp and a UV filter (wavelength greater than 400 nm) group as a visible light source. 30 mg of the photocatalyst prepared in Examples 1-4 and Comparative Examples 1-2 was weighed into a quartz reaction tube containing 50 ml of norfloxacin solution (10 mg / L), and the solution pH was adjusted to 7. The entire system was first placed in a dark condition and stirred at constant temperature for 30 min to establish adsorption-desorption equilibrium. The xenon lamp was turned on to enter the light reaction stage, and at light exposure times of 0 min, 15 min, 30 min, 45 min, 60 min, 75 min, and 90 min, a certain amount of reaction solution was filtered and its absorbance was measured using a UV-visible spectrophotometer. The photocatalytic degradation efficiency of the catalyst for norfloxacin wastewater at different light exposure times was calculated. The solution absorbance was tested in triplicate, and the average value was taken.

[0061] Figure 4 The photocatalytic degradation effect of the photocatalyst prepared in Examples 1-4 and Comparative Examples 1-2 on norfloxacin was plotted. Figure 4 It was found that the BiOBiW-0.8 prepared in Example 3 had the best degradation efficiency. In a 50 mL solution of norfloxacin with a mass concentration of 10 mg / L and a pH of 7, the degradation rate of BiOBiW-0.8 reached 94.84% under the condition of 30 mg of BiOBiW-0.8 and a light reaction time of 90 min. The BiOIO3 / Bi2WO6 heterojunction photocatalyst prepared in Examples 1-4 had a significantly better photocatalytic degradation effect on norfloxacin than pure BiOIO3 and pure Bi2WO6.

[0062] The above examples are only used to explain the technical solutions of the present application and are not limiting. Although the above examples specifically illustrate the present application, those skilled in the art will understand that the specific embodiments of the present application can still be modified or replaced by equivalents without departing from the spirit and scope of the present application, and any modification and equivalent replacement thereof should be covered within the protection scope of the present application.

Claims

1. Application of bismuth tungstate doped bismuth oxyiodide heterojunction photocatalyst in photodegradation of organic matter norfloxacin, characterized in that, The preparation method of the catalyst comprises the following steps: S1, preparing BiOIO3: Bi(NO3)3·5H2O is dissolved in deionized water, the molar ratio of Bi(NO3)3·5H2O to deionized water is 1:4500, ultrasonic homogenization, Bi(NO3)3 solution is obtained, then KIO3 is added to the Bi(NO3)3 solution, the molar ratio of Bi(NO3)3·5H2O to KIO3 is 1:1, magnetic stirring for 30-60 min, a mixed solution is obtained; the mixed solution is loaded into a reaction kettle, and reacted at 145-155℃ for 4-6h, washed with deionized water after cooling, dried to obtain BiOIO3 powder, ready for use; S2, preparing BiOIO3 / Bi2WO6 heterojunction photocatalyst: BiOIO3 powder obtained in step S1 is added to deionized water, the molar ratio of BiOIO3 powder to deionized water is 1:18, ultrasonic homogenization, BiOIO3 mixed solution is obtained, then Bi(NO3)3·5H2O, Na2WO4·2H2O and surfactant are added to the BiOIO3 mixed solution, stirring and mixing uniformly, a mixed solution is obtained, finally the mixed solution is loaded into a reaction kettle, reacted at 120-130℃ for 18-30h, washed with deionized water and dried to obtain bismuth tungstate doped bismuth iodate oxide heterojunction photocatalyst, the surfactant is one or both of oleylamine and cetyltrimethylammonium bromide; the molar ratio of Bi(NO3)3·5H2O, Na2WO4·2H2O and surfactant is 2:1:(0.14-0.18); the molar ratio of BiOIO3 to Bi2WO6 is 25:(40-90).

2. The use of the Bi2WO6 doped BiOIOx heterojunction photocatalyst according to claim 1 in the photodegradation of the organic substance norfloxacin, characterized in that, In step S1, the drying process conditions are 60-80℃ for 1-3h.

3. The use of the Bi2WO6 doped BiOIO3 heterojunction photocatalyst according to claim 1 in the photodegradation of the organic substance norfloxacin, characterized in that, In step S2, the surfactant is a combination of oleylamine and cetyltrimethylammonium bromide in a mass ratio of 1:(5-8).

4. The use of the Bi2WO6 doped BiOIOx heterojunction photocatalyst according to claim 1 in the photodegradation of the organic substance norfloxacin, characterized by, In step S2, the drying process conditions are 50-70℃ for 10-18h.

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