Phosphorus-vanadium co-doped bismuth oxychloride for enhancing built-in electric field as well as preparation method and application of phosphorus-vanadium co-doped bismuth oxychloride

Abstract

The invention relates to phosphorus-vanadium co-doped bismuth oxychloride for enhancing a built-in electric field and a preparation method and application thereof. The preparation method comprises the following steps: dissolving bismuth nitrate pentahydrate and sodium hypophosphite monohydrate in ethylene glycol to obtain a solution A; dissolving potassium chloride and ammonium metavanadate in water to obtain a solution B; the solution B is dropwise added into the solution A which is being stirred, full stirring reaction is carried out at room temperature, and then hydrothermal reaction is carried out, so that the IEF of the BiOCl material is uniformly and effectively improved, and the specific improvement effect on the photocatalytic performance is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalysis, and in particular relates to phosphorus-vanadium co-doped bismuth oxychloride for enhancing a built-in electric field, and a preparation method and application thereof. Background Art

[0002] The role of the built-in electric field (IEF) in the photocatalytic process is crucial. IEF can effectively promote the separation of photogenerated carriers (electrons and holes) and significantly improve the efficiency of photocatalytic reactions. Correctly understanding and enhancing IEF can greatly improve the photocatalytic performance of semiconductor materials because IEF not only reduces the recombination of electron-hole pairs, but also guides the migration of carriers to surface active sites, thereby accelerating the photocatalytic reaction. Although the importance of IEF has been widely recognized, how to effectively control and enhance IEF through material design, especially in semiconductor materials with complex structures and electronic properties, remains a challenge. The strength of IEF directly affects the separation efficiency of carriers, thereby affecting the activity of photocatalysts. Enhancing IEF by adjusting the electronic structure of semiconductor materials has been proven to be an effective way to improve photocatalytic performance. In this context, doping strategies have been widely studied and applied, aiming to adjust the electronic structure and surface properties of semiconductors by introducing foreign atoms or ions. Although doping strategies have great potential in theory, they also face the problem of limited IEF intensity due to enhancement only from specific crystal planes or atomic layers.

[0003] Therefore, focusing on exploring a novel nonmetal-metal co-doping strategy that can uniformly and effectively enhance IEF is crucial to improve the performance of photocatalysts. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing phosphorus-vanadium co-doped bismuth oxychloride with enhanced built-in electric field, aiming to uniformly and effectively improve the IEF of BiOCl material by precisely controlling the types and proportions of doping elements, and to reveal the influence mechanism of co-doping on the electronic structure of BiOCl and its specific effect on improving the photocatalytic performance through theoretical calculation and experimental verification.

[0005] The purpose of the present invention is achieved through the following technical solutions: A method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing a built-in electric field, specifically comprising the following steps: Dissolving bismuth nitrate pentahydrate and sodium hypophosphite monohydrate in ethylene glycol to obtain solution A; Dissolve potassium chloride and ammonium metavanadate in water to obtain solution B; Solution B was added dropwise into the stirring solution A, and after sufficient stirring at room temperature, a hydrothermal reaction was performed.

[0006] Furthermore, the mass ratio of the bismuth nitrate pentahydrate, sodium hypophosphite monohydrate and ammonium metavanadate is 281.44:(2.47-4.3):1.

[0007] Furthermore, the mass ratio of potassium chloride to ammonium metavanadate is 41.63:1.

[0008] Furthermore, the volume ratio of ethylene glycol to water is (5-2):(1-3). Furthermore, the ratio of ethylene glycol to water is 4:1.

[0009] Furthermore, the hydrothermal reaction time is 3-24h.

[0010] Furthermore, the hydrothermal reaction pressure is 1-2 MPa.

[0011] Further, solution B was added dropwise into the stirred solution A to adjust the pH to 1.5-3.5, and further the pH was adjusted to 2.5.

[0012] Another object of the present invention is to provide the phosphorus-vanadium co-doped bismuth oxychloride with enhanced built-in electric field for use as a photocatalyst in removing organic pollutants in water.

[0013] As a more preferred technical solution of the present invention, the organic pollutants include one or more of ciprofloxacin, ofloxacin, levofloxacin, norfloxacin, moxifloxacin, gatifloxacin, marbofloxacin, and tetracycline hydrochloride. More preferred is the application of removing ciprofloxacin, and the dosage thereof is 0.05-0.4 g / L.

[0014] Compared with the prior art, the photocatalyst created by the present invention can achieve the following beneficial effects: The photocatalyst preparation method provided by the present invention has the advantages of simple operation, environmental friendliness and good repeatability, and provides method support for the subsequent long-term large-scale preparation of photocatalytic materials for efficiently treating complex pharmaceutical wastewater.

[0015] The present invention utilizes phosphorus-vanadium co-doping to enhance the built-in electric field of bismuth oxychloride and evaluates the performance of phosphorus-vanadium co-doped BiOCl in treating refractory organic pollutants in water. It can selectively remove highly hydrophilic pollutants from complex wastewater and has a high affinity for anions (HCO3 − , NO3 − and Cl − The photocatalysts have good anti-interference performance in water matrix (tap water and secondary effluent, etc.), providing a new strategy for the development of efficient and stable photocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 The morphology characterization images of Comparative Example 1 and Example 2, wherein a is the transmission electron microscope (SEM) morphology characterization of Comparative Example 1, b is the SEM morphology characterization of Example 2, and c is the high magnification transmission electron microscope (HRTEM) image of Example 2; Figure 2 The X-ray diffraction (XRD) patterns of Examples 1 to 3 and Example 2 are compared; Figure 3 Fourier transform infrared (FT-IR) spectra of comparative examples 1 to 3 and example 2; Figure 4 X-ray photoelectron spectroscopy (XPS) for comparative examples 1 to 3 and example 2; Figure 5 The nitrogen adsorption-desorption curves (BET) of comparative examples 1 to 3 and example 2 are used to calculate the specific surface area; Figure 6 The ultraviolet-visible diffuse reflectance spectra (UV-visDRS) of comparative examples 1 to 3 and example 2 are shown; Figure 7 IEF test for comparative examples 1 to 3 and example 2; Figure 8 To compare the efficiency of removing ciprofloxacin in Examples 1 to 3 and Example 2; Fig. 9 is the efficiency of removing ciprofloxacin in Examples 1 to 4; Fig.10 is the efficiency of removing ciprofloxacin in Examples 5 to 8; Fig.11 is the efficiency of removing CIP in Examples 9 to 11; Fig.12 is the efficiency of removing CIP in Examples 12 to 14; Fig.13 is the CIP removal efficiency of Examples 15 to 17; Fig.14 The efficiency of removing various other organic pollutants by BOC-PV of Example 2; Fig.15 The removal efficiency of ciprofloxacin by BOC-PV of Example 2 under the presence of different anions; Fig.16 is the ciprofloxacin removal efficiency of the BOC-PV of Example 2 under different actual water matrix conditions; Fig.17Identification of the main active species for the removal of ciprofloxacin by BOC-PV of Example 2; Fig.18 is the efficiency of removing ciprofloxacin by the BOC-PV cycle of Example 2; Fig.19 XRD patterns of BOC-PV of Example 2 before and after removal. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with specific embodiments, and the embodiments provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The embodiments provided below can be used as a guide for further improvement by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way. It should be noted that, in the absence of conflict, the features in the embodiments and the embodiments in the present invention can be combined with each other.

[0018] The experimental methods in the following embodiments are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments are conventional biochemical reagents unless otherwise specified and can be obtained from commercial sources. The room temperature in the following embodiments is 30°C. The hydrothermal reaction is carried out in a 100 mL sealed reactor under heating, with a pressure of 1.5 MPa and a drop rate of 2 seconds per drop. Slow drop addition will allow the substance to react fully. The molar concentration of bismuth nitrate pentahydrate in the solution A is 0.09 mol / L-0.1 mol / L. The molar concentration of potassium chloride in the solution B is 0.4 mol / L-0.5 mol / L. Sodium hydroxide is used for pH adjustment. The total amount of ethylene glycol and water used in solution A and solution B is 50 mL.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0020] Comparative Example 1 1.9701 g of bismuth nitrate pentahydrate was dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride was dissolved in 10 mL of water to obtain solution B, solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 12 hours, which was recorded as BOC.

[0021] Comparative Example 2 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, and 0.2914 g of potassium chloride was dissolved in 10 mL of water to obtain solution B. Solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-P.

[0022] Comparative Example 3 1.9701 g of bismuth nitrate pentahydrate was dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-V.

[0023] Example 1 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 3 hours, which was recorded as BOC-PV-3h.

[0024] Example 2 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV.

[0025] Example 3 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After fully stirring the reaction at room temperature, a hydrothermal reaction was carried out at 180°C for 12 hours, which was recorded as BOC-PV-12h.

[0026] Example 4 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 24 hours, which was recorded as BOC-PV-24h.

[0027] Example 5 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 41.67 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 8.33 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-5:1.

[0028] Example 6 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A to adjust the pH to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-4:1.

[0029] Example 7 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 30 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 20 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A to adjust the pH to 2.5. After fully stirring the reaction at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-3:2.

[0030] Example 8 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 20 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 30 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A to adjust the pH to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-2:3.

[0031] Example 9 1.9701 g of bismuth nitrate pentahydrate and 0.0173 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-P-4.1.

[0032] Example 10 1.9701 g of bismuth nitrate pentahydrate and 0.0259 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-P-6.1.

[0033] Embodiment 11 1.9701 g of bismuth nitrate pentahydrate and 0.0301 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-P-7.1.

[0034] Example 12 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0047 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-V-10.

[0035] Embodiment 13 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0080 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After fully stirring the reaction at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-V-17.

[0036] Embodiment 14 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0094 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-V-20.

[0037] Embodiment 15 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A without adjusting the pH. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-no pH adjustment.

[0038] Example 16 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 1.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-pH=1.5.

[0039] Embodiment 17 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 3.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C for 6 hours, which was recorded as BOC-PV-pH=3.5.

[0040] Embodiment 18 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After fully stirring the reaction at room temperature, a hydrothermal reaction was carried out at 180°C, a pressure of 1 MPa, and a time of 6 hours, which was recorded as BOC-PV-3M.

[0041] Embodiment 19 1.9701 g of bismuth nitrate pentahydrate and 0.0214 g of sodium hypophosphite monohydrate were dissolved in 40 mL of ethylene glycol to obtain solution A, 0.2914 g of potassium chloride and 0.0070 g of ammonium metavanadate were dissolved in 10 mL of water to obtain solution B, and solution B was added dropwise to the stirring solution A, and the pH was adjusted to 2.5. After sufficient stirring at room temperature, a hydrothermal reaction was carried out at 180°C, a pressure of 2 MPa, and a time of 6 h, which was recorded as BOC-PV-2M.

[0042] pass Figure 1From the SEM morphology characterization of comparative example 1 (a) and the SEM morphology characterization of example 2 (b), it can be seen that the BOC of comparative example 1 and the BOC-PV of example 2 are both ultra-thin nanosheet structures. Figure 1 Figure c is a HRTEM image of BOC-PV of Example 2, and the inset shows that BOC-PV of Example 2 exhibits lattice diffraction fringes corresponding to the (101) plane and the (110) plane, respectively, with fringing spacings of 0.345 nm and 0.275 nm, respectively. Ethylene glycol provides viscosity that facilitates the reaction of substances in the solvent.

[0043] The XRD comparison of Comparative Examples 1 to 3 and Example 2 is as follows: Figure 2 As shown in FIG. 1 , it can be seen that the diffraction peaks at 25.8° and 32.5° correspond to the (101) and (110) crystal planes of PVP / CN of Comparative Example 1, respectively. With the doping of P and V, the peak positions of the diffraction peaks shift slightly, as shown in FIG. Figure 1 Taking the (110) crystal plane as an example, compared with the BOC of Comparative Example 1, the peak position of BOC-P of Comparative Example 2 shifts to the left after P doping, and the peak position of BOC-V of Comparative Example 3 shifts to the right after V doping, indicating the successful doping of P and V.

[0044] FT-IR comparison of Comparative Examples 1 to 3 and Example 2 Figure 3 As shown. Comparative Examples 1 to 3 and Example 2 all exhibit three infrared absorption peaks. -1 The peaks at 1620 and 3440 cm are caused by the vibration of Bi-O bonds. -1 The nearby vibration bands are assigned to the bending and stretching vibrations of adsorbed water and hydroxyl groups. The new characteristic peak appears at 960 cm-1 for BOC-P and BOC-PV. -1 It is related to the stretching vibration of the PO bond.

[0045] The XPS results of Comparative Examples 1 to 3 and Example 2 are as follows: Figure 4 As shown. Figure a and Figure b are the Bi4f XPS and Cl 2p XPS of Example 1, respectively. The peaks at 164.68 and 159.38 eV correspond to Bi 4f 7 / 2 and Bi 4f 5 / 2, respectively, confirming that Bi 3+ The two strong peaks at about 197.6 and 199.2 eV are attributed to Cl 2p 3 / 2 and Cl 2p 1 / 2, indicating the successful synthesis of BiOCl.

[0046] Comparative Examples 1 to 3 and Example 2 Test N 2 The adsorption-desorption curve is Figure 5As shown in the figure, the specific surface areas (SSA) of BOC, BOC-P, BOC-V and BOC-PV samples were obtained. According to the IUPAC standard, they all showed typical type IV isotherms. The specific surface areas of BOC, BOC-P, BOC-V and BOV-PV were 12.10, 31.82, 24.06 and 55.96 m 2 / g. The above results show that the doping of P and V increases the specific surface area.

[0047] The UV-visible diffuse reflectance spectra (UV-visDRS) of Comparative Examples 1 to 3 and Example 2 are compared as follows: Figure 6 As shown in Figure 2, there is no obvious change in the absorption band edge position. The results show that the doping of P and V has limited effect on the improvement of light absorption capacity.

[0048] The IEF intensity comparison of Comparative Examples 1 to 3 and Example 2 is as follows: Figure 7 As shown. The built-in electric field strengths of comparative examples 2-3 and example 2 are 3.9, 6.2 and 17.7 respectively (the strength of BOC of comparative example 1 is set to 1). The results show that the doping of P and V effectively improves the built-in electric field strength, and PV co-doping can synergistically improve the built-in electric field strength.

[0049] Application Example 1 Comparison of the use of Examples 1 to 3 and Examples 1 to 9 in removing ciprofloxacin First, 0.001 g of the catalysts of Comparative Examples 1 to 3 and Example 2 were placed in 70 mL of a ciprofloxacin aqueous solution (CIP, 10 mg / L). Then, stirring was started and the reaction was activated by visible light. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a filter having a wavelength less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illuminated area = 3.34 cm 2 During the reaction, 1.0 mL of sample was collected every 15 minutes and filtered through a 0.22 μm filter membrane. The concentration of ciprofloxacin was determined by Thermo Fisher high performance liquid chromatography. Figure 8 The results show that compared with the degradation rate of BOC in Comparative Example 1, which is only 17%, the degradation rate of BOC-PV in Example 2 is increased to 90%, indicating that the built-in electric field enhanced by the phosphorus-vanadium co-doping strategy can effectively improve the photocatalytic ability.

[0050] The efficiency of removing CIP in Examples 1 to 4 is as follows: Fig. 9 Compared with BOC-PV-24h (77.32%) of Example 1, BOC-PV-12h (79.77%) of Example 2, and BOC-PV-3h (84.53%) of Example 4, the efficiency of BOC-PV-12h in removing CIP in Example 3 is 90%.

[0051] The efficiency of removing CIP in Examples 5 to 8 is as follows: Fig.10 Compared with BOC-PV-5:1 (85.62%) of Example 5, BOC-PV-3:2 (80.81%) of Example 7, and BOC-PV-2:3 (75.82%) of Example 8, the efficiency of BOC-PV-4:1 of Example 6 in removing CIP is 90%.

[0052] The efficiency of removing CIP in Examples 9 to 11 is as follows Fig.11 Compared with BOC-PV-P-4.1 (66.74%) of Example 9, BOC-PV-P-6.1 (75.62%) of Example 10, and BOC-PV-P-7.1 (71.88%) of Example 11, the efficiency of BOC-PV in Example 2 in removing CIP is 90%.

[0053] The efficiency of removing CIP in Examples 12 to 14 is as follows: Fig.12 Compared with BOC-PV-V-10 (70.02%) of Example 12, BOC-PV-V-17 (72.32%) of Example 13, and BOC-PV-V-20 (68.15%) of Example 14, the efficiency of BOC-PV in Example 2 in removing CIP is 90%.

[0054] The efficiency of removing CIP in Examples 15 to 17 is as follows Fig.13 Compared with BOC-PV without pH adjustment in Example 15 (62.34%), BOC-PV in Example 16 with pH=1.5 (72.08%), and BOC-PV in Example 17 with pH=3.5 (73.36%), the efficiency of BOC-PV in Example 2 in removing CIP is 90%.

[0055] Application Example 2 Application of BOC-PV in Example 2 to remove different organic pollutants First, 0.001 g of the catalysts of Examples 1 to 4 were respectively placed in 70 mL of aqueous solution containing ofloxacin (OFL, 10 mg / L), levofloxacin (LVFX, 10 mg / L), norfloxacin (NOR, 10 mg / L), moxifloxacin (MOX, 10 mg / L), gatifloxacin (GAT, 10 mg / L), and marbofloxacin (MAR, 10 mg / L). Then, stirring was started and the reaction was activated by visible light. Visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a filter having a wavelength less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illuminated area = 3.34 cm 2During the reaction, 1.0 mL of sample was collected every 15 minutes and filtered through a 0.22 μm filter membrane. The concentrations of different organic pollutants were detected by Thermo Fisher high performance liquid chromatography. Fig.14 The results show that BOC-PV can efficiently degrade a variety of organic pollutants.

[0056] Application Example 3 Environmental interference experiment of BOC-PV in Example 2 The photocatalytic removal efficiency of CIP by BOC-PV in Example 2 under different anion conditions is as follows: Fig.15 As shown. The BOC-PV of Example 2 is − 、NO3 − and HCO3 − The removal efficiency of CIP under the presence of anions was 89.0, 85.3, and 89.3% respectively. The results showed that the removal efficiency of CIP under anion conditions did not change significantly.

[0057] The CIP removal efficiency of the BOC-PV of Example 2 under different actual water matrix conditions is as follows Fig.16 As shown. Compared with the removal efficiency of CIP in deionized water matrix (89%), the removal efficiency of CIP in tap water of BOC-PV of Example 2 remained basically unchanged, while the removal rate of CIP in secondary effluent was reduced to 65.2%. The slight decrease in the removal rate in secondary effluent indicated that the organic pollutants contained in the water matrix may become the attack site of active species. The above shows that BOC-PV based on Example 2 has certain anti-interference performance.

[0058] Application Example 4 BOC-PV of Example 2 removes the main active species in the CIP process The identification results of the main active species of CIP removed by BOC-PV in Example 2 are as follows Fig.17 Except for e−, all active species detected contribute to the degradation of pollutants, and the order of contribution is: •O 2− > 1 O2>h + >•OH. This indicates that the enhancement of IEF effectively promotes the separation of photogenerated carriers, thereby promoting the generation of a variety of active species and improving photocatalytic degradation.

[0059] Application Example 5 Application of BOC-PV cycle to remove CIP in Example 2 First, 0.001 g of the catalysts of Examples 1 to 4 were placed in 70 mL of a ciprofloxacin aqueous solution (CIP, 10 mg / L). Then, stirring was started and the reaction was activated by visible light. The visible light was provided by a 300.0 W xenon lamp (CEL-HXF300, Beijing Zhongjiao Jinyuan Co., Ltd.) with a wavelength filter less than 420 nm. The light intensity was 122.9 mW / cm 2 (Illuminated area = 3.34 cm 2 ). During the reaction, 1.0 mL of sample was collected every 15 minutes and filtered through a 0.22 μm filter membrane. After 1 h of reaction, the sample was centrifuged and dried for the next removal. This step was repeated 4 times, and the concentration of ciprofloxacin was detected by Thermo Fisher HPLC. The CIP removal efficiency of BOC-PV in Example 2 is shown in FIG. Fig.18 As shown, after four cycles, the CIP degradation efficiency of the BOC-PV of Example 2 was only reduced by 5.4%. The results show that the BOC-PV of Example 2 has good cycle performance.

[0060] The XRD patterns of BOC-PV before and after the reaction of Example 2 are as follows: Fig.19 The XRD patterns of the BOC-PV of Example 2 before and after the reaction are basically unchanged, indicating that the BOC-PV of Example 2 has a stable physical structure.

[0061] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing built-in electric field, characterized in that: Specifically, the method comprises the following steps: dissolving bismuth nitrate pentahydrate and sodium hypophosphite monohydrate in ethylene glycol to obtain solution A; dissolving potassium chloride and ammonium metavanadate in water to obtain solution B; adding solution B dropwise into solution A being stirred, stirring the mixture sufficiently for reaction at room temperature, and then performing a hydrothermal reaction.

2. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 1, characterized in that: The mass ratio of the bismuth nitrate pentahydrate, sodium hypophosphite monohydrate and ammonium metavanadate is 281.44:(2.47-4.3):

1.

3. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 2, characterized in that: The mass ratio of potassium chloride to ammonium metavanadate is 41.63:

1.

4. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 1, characterized in that: The volume ratio of ethylene glycol to water is (5-2):(1-3).

5. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 4, characterized in that: The ratio of ethylene glycol to water is 4:

1.

6. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 1, characterized in that: The hydrothermal reaction time is 3-24h.

7. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 1, characterized in that: Solution B was added dropwise to the stirring solution A and the pH was adjusted to 1.5-3.

5.

8. The method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field according to claim 7, characterized in that: The pH was adjusted to 2.

5.

9. A photocatalyst, characterized in that: The method is prepared by the method for preparing phosphorus-vanadium co-doped bismuth oxychloride for enhancing the built-in electric field as described in any one of claims 1 to 8.

10. Use of the photocatalyst as claimed in claim 9 in removing organic pollutants in water.

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