Process for preparing bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particle loading

Abstract

The application discloses a preparation method of a bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particle loading, which comprises the following steps: 1) synthesizing bismuth vanadate by using a hydrothermal method; 2) introducing bismuth vacancies into the bismuth vanadate obtained in the step 1) by using a deep eutectic solvent treatment method to obtain bismuth vanadate with bismuth vacancies; 3) loading copper particles on the surface of the bismuth vanadate with bismuth vacancies obtained in the step 2) by using a photodeposition method to form a copper-loaded composite catalyst; and 4) performing corona polarization treatment on the copper-loaded composite catalyst obtained in the step 3), and the bismuth vanadate composite photocatalyst is obtained. The bismuth vanadate composite photocatalyst prepared by the method has high catalytic activity in a reaction of converting methane into ethanol.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a method for preparing a bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles, and the obtained bismuth vanadate composite photocatalyst. Background Technology

[0002] In existing technologies, bismuth vanadate (BiVO4), as a photocatalytic material with good visible light response and chemical stability, has been widely used in photocatalytic reactions. However, bismuth vanadate suffers from problems such as severe carrier recombination, insufficient surface active sites, and weak electron mobility, which limit further improvement in its catalytic performance. To overcome these problems, researchers have adopted different modification methods, including defect modulation, surface modification, and crystal plane engineering.

[0003] The introduction of vacancies has been shown to enhance the polarization effect of ferroelectric materials, promoting the efficient separation and migration of charge carriers. However, single defect modulation has not been sufficient to address the problem of insufficient surface reactive sites. Loading copper particles can effectively provide more surface active sites and promote the activation of methane molecules. Corona polarization, as a commonly used polarization enhancement method, can induce a more stable orientation polarization structure within the material, enhancing the built-in electric field and further promoting the directional separation and migration of photogenerated charge carriers. However, bismuth vanadate itself is not a ferroelectric material; it lacks spontaneous polarization and cannot promote the directional separation and migration of photogenerated charge carriers through the built-in electric field generated by polarization. Therefore, this issue needs to be addressed. Summary of the Invention

[0004] To address the aforementioned problems of severe carrier recombination and insufficient surface active sites in bismuth vanadate, this invention provides a method for preparing a bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles, as well as the resulting bismuth vanadate composite photocatalyst.

[0005] The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported by the present invention includes the following steps: 1) Bismuth vanadate was synthesized by hydrothermal method.

[0006] 2) Bismuth vacancies are introduced into the bismuth vanadate obtained in step 1) by deep eutectic solvent (DES) treatment method to obtain bismuth vanadate with bismuth vacancies; by adjusting the defect state and charge distribution, the local polarization effect of the material is enhanced.

[0007] 3) Copper particles are loaded onto the surface of bismuth vanadate with bismuth vacancies obtained in step 2) using photodeposition to form a copper-loaded composite catalyst; the loading of copper particles can provide more surface active sites, promoting the activation and reaction of methane molecules.

[0008] 4) The copper-supported composite catalyst obtained in step 3) is subjected to corona polarization treatment to obtain bismuth vanadate composite photocatalyst; the built-in electric field and polarization effect of the material can be further enhanced by the external electric field, thereby improving the separation efficiency of photogenerated carriers.

[0009] The hydrothermal method in step 1) is as follows: Ammonium vanadate and bismuth nitrate pentahydrate are dissolved in nitric acid of equal concentration at a molar ratio of 1:0.9-1.1 to obtain a first solution and a second solution; then the second solution is slowly added dropwise to the first solution to obtain a stable and uniform yellow solution; then the pH of the yellow solution is adjusted to 1.8-2.2 with ammonia until an orange precipitate is formed to obtain a suspension slurry; then the suspension slurry is transferred to a Teflon-lined stainless steel high-pressure reactor and reacted at 180℃-220℃ for 20-28 hours, followed by cooling, filtration, separation, washing, and drying to obtain a bright yellow powder of bismuth vanadate.

[0010] The method for treating the eutectic solvent in step 2) is as follows: at room temperature, choline chloride and ethylene glycol are mixed in a molar ratio of 1:1.8-2.2 to obtain a eutectic solvent; then, the above bismuth vanadate is immersed in the eutectic solvent and heated to 60℃-100℃ and kept for 8-24 hours; then the product is centrifuged, washed and dried to obtain bismuth vanadate with bismuth vacancies.

[0011] The photodeposition method in step 3) is as follows: bismuth vanadate with bismuth vacancies is added to deionized water and mixed evenly; then copper nitrate trihydrate is added and mixed evenly, followed by methanol as a hole sacrificial agent and mixed evenly. Then, the mixture is irradiated with a 200-400W xenon lamp for 5-15 hours. The product is then centrifuged, washed, and dried to obtain a copper-supported composite catalyst. The mass ratio of bismuth vanadate with bismuth vacancies, copper nitrate trihydrate, and methanol is 1:0.1-0.3:10-15.

[0012] The corona polarization treatment in step 4) is as follows: the powder of the above copper-supported composite catalyst is evenly coated on the surface of a copper plate, an appropriate amount of alcohol is added for fixation, and then dried at room temperature to obtain a dried product. The dried product is then placed in a corona polarization device and subjected to corona polarization treatment at a voltage of 4-6kV for a polarization time of 1-4h to obtain a bismuth vanadate composite photocatalyst.

[0013] The present invention also provides a bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles, which is prepared using the above-described method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles.

[0014] Beneficial Effects: The method of this invention significantly improves the carrier separation and migration ability, surface active sites, and reaction performance of bismuth vanadate materials through the synergistic effect of bismuth vacancy regulation, copper particle loading, and corona polarization, thereby greatly enhancing their catalytic performance in photocatalytic methane conversion reactions. Significantly Enhanced Carrier Separation and Migration: By introducing bismuth vacancies into bismuth vanadate, the local polarization effect of the material is enhanced, improving the separation and migration efficiency of photogenerated carriers. Corona polarization treatment further enhances the built-in electric field, promoting the directional migration of photogenerated electrons and holes, avoiding the severe carrier recombination problem in traditional bismuth vanadate materials. Effective Increase of Surface Active Sites: The loading of copper particles provides additional surface active sites, especially with the uniform distribution of copper particles, effectively enhancing the catalyst's adsorption and activation ability for methane molecules. Significantly Improved Catalytic Performance: In photocatalytic methane conversion reactions, the Cu / V... Bi -BVO catalysts exhibit significantly improved catalytic performance. Compared to unpolarized samples, Cu / V catalysts treated with corona polarization show improved performance. Bi The -BVO-P catalyst exhibited a higher ethanol production rate in the reaction of methane to ethanol, with an increase of more than 2 times that of the original sample, indicating that the catalytic activity of the catalyst was significantly enhanced. Attached Figure Description

[0015] Figure 1 The images shown are scanning electron microscope (SEM) images of the samples prepared in this invention; where (a) is an image of BVO, and (b) is an image of V. Bi The graphs for -BVO, (c) is the Cu / BVO graph, and (d) is the Cu / V graph. Bi -BVO diagram; Figure 2 The Cu / V obtained in this invention Bi -X-ray energy dispersive spectroscopy elemental analysis results of BVO; where (a) is the SEM image of the test area, (b) is the surface distribution map of O element, (c) is the surface distribution map of Bi element, (d) is the X-ray energy dispersive spectroscopy elemental analysis results, (e) is the surface distribution map of V element, and (f) is the surface distribution map of Cu element. Figure 3 The XRD patterns of the samples prepared in this invention are shown below. Figure 4 The images show the X-ray photoelectron spectroscopy (XPS) analysis of the samples prepared in this invention, where (a)-(d) are the elemental spectra of Bi, V, O and Cu, respectively, (e) is the full XPS spectrum of the sample, and (f) is the LMM spectrum of Cu. Figure 5The following are characterization diagrams of the band positions of the samples prepared in this invention; wherein, (a) is the UV-Vis absorption spectrum, (b) is the Tauc plot of the UV-Vis absorption spectrum, (c) is the XPS valence band spectrum of each sample, and (d) is the band structure diagram. Figure 6 The PL spectra of each sample prepared in this invention are shown below. Figure 7 The TRPL curves of each sample obtained in this invention are shown. Figure 8 The EPR spectra of BVO, BVO-DES-8H and BVO-DES-24H prepared in this invention are shown. Figure 9 BVO and V obtained in this invention Bi -Contact angle test results of BVO; where (a) is the BVO graph and (b) is the V Bi -BVO diagram; Figure 10 The Cu / V obtained in this invention Bi -BVO and Cu / V Bi -BVO corona polarized sample Cu / V Bi -BVO-P PL spectrum; Figure 11 V obtained in this invention Bi -BVO piezoelectric microscopy pattern; where (a) is V Bi -PFM amplitude curve of BVO sample, (b) is V Bi - PFM phase curve of BVO sample; Figure 12 The image shows the photocatalytic CH4 conversion performance of various samples prepared in this invention; where (a) shows the results of different samples (1, 2, 3, 4, and 5 represent BVO, V, and V, respectively). Bi -BVO, Cu / BVO, Cu / V Bi -BVO, Cu / V Bi (b) shows the results of -BVO-P), and (b) shows the Cu / V ratio for different Cu mass fractions. Bi Performance results of photocatalytic CH4 conversion of -BVO. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but the present invention is not limited to the embodiments.

[0017] The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported by the present invention includes the following steps.

[0018] 1) Dissolve 10.0 mmol ammonium vanadate (NH4VO3) and 10.0 mmol bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) in 45 mL of 2.0 M nitric acid (HNO3) and 15 mL of 2.0 M nitric acid (HNO3), respectively, to obtain a first solution and a second solution. Then, slowly add the second solution dropwise to the first solution to obtain a stable and homogeneous yellow solution. Under continuous stirring, adjust the pH of the yellow solution to approximately 2 using ammonia water (NH3·H2O). Next, further adjust the pH of the yellow solution until an orange precipitate forms, and stir for 30 min to stabilize the pH and ensure complete precipitate formation. After the precipitation reaction continues for 2 h, an orange suspension (approximately 70 mL) is obtained. This orange suspension is transferred to a 100 mL Teflon-lined stainless steel high-pressure reactor and reacted at 200 °C for 24 h. After the reaction was completed, the autoclave was cooled to room temperature (25°C), the product was collected by centrifugation, washed alternately with water and ethanol, and dried in a vacuum oven at 60°C for 24 hours to finally obtain a bright yellow powder of bismuth vanadate (BiVO4), denoted as BVO.

[0019] 2) At room temperature (25℃), choline chloride (C5H) is added... 14 C10 (ClNO) and ethylene glycol (C2H6O2) were mixed in a 1:2 molar ratio to obtain a deep eutectic solvent. 500 mg of the above BVO powder was immersed in 5 g of the deep eutectic solvent (DES), and the temperature was raised to 80 °C and maintained for 10 h. The resulting product was collected by centrifugation, washed alternately with water and ethanol, and then dried in a vacuum oven at 60 °C for 10 h to obtain bismuth vanadate with bismuth vacancies, denoted as V. Bi -BVO.

[0020] 3) Take 200mg of the above-mentioned vitamin V Bi -BVO was added to 100 mL of deionized water and stirred until homogeneous. Then, 37.9 mg of copper nitrate trihydrate (Cu(NO3)2·3H2O) was added, stirred again, and ultrasonically dispersed at 40 kHz for 10 min using an ultrasonic cleaner. Finally, 3 mL of methanol (CH3OH) (approximately 2373 mg) was added as a hole sacrificial agent. After homogeneous mixing, the mixture was irradiated with a 300 W xenon lamp for 10 h while stirred. The resulting product was collected by centrifugation, washed alternately with water and ethanol, and then dried in a vacuum oven at 60 °C for 10 h to obtain a copper-supported composite catalyst with a copper mass fraction of 5%, denoted as Cu / V. Bi -BVO.

[0021] 4) Wuhan Bailibo Testing Service Co., Ltd. was commissioned to test the above Cu / V. Bi -BVO was subjected to corona polarization treatment, the specific process of which is as follows: 400mg of the above Cu / V Bi-BVO powder was evenly coated onto the surface of a copper plate, then fixed with an appropriate amount of alcohol, and subsequently dried at room temperature (25°C) to ensure uniform powder adhesion to the copper plate surface, resulting in a dried product. This dried product was then subjected to corona polarization treatment using a corona high-voltage polarizer (SPD-20KV-POS). The conditions for corona polarization were: room temperature (25°C), voltage (6kV), and polarization time (1 hour). This yielded a bismuth vanadate composite photocatalyst, denoted as Cu / V. Bi -BVO-P. The above corona polarization treatment conditions can provide a stable external electric field environment for the sample, thereby causing the polarization units inside the material to align and thus introducing a stable polarization electric field inside the material.

[0022] Performance testing To verify whether vacancies can be effectively generated in step 2), a control sample was prepared. That is, in step 2), the "temperature increased to 80°C and held for 10 h" was changed to "temperature increased to 80°C and held for 8 h" and "temperature increased to 80°C and held for 24 h". Otherwise, it was the same as step 2), and the products were named BVO-DES-8H and BVO-DES-24H, respectively.

[0023] In addition, in order to conduct performance comparison tests, copper-supported composite catalysts with copper mass fractions of 10%, 15%, and 20% were synthesized through step 3) above.

[0024] In addition, for performance comparison tests, a Cu / BVO catalyst was prepared by photodeposition of copper particles onto the surface of BVO. Specifically, 200 mg of the BVO obtained in step 1) was added to 100 mL of deionized water and stirred until homogeneous. Then, 37.9 mg of copper nitrate trihydrate (Cu(NO3)2·3H2O) was added, stirred again, and ultrasonically dispersed at 40 kHz for 10 min using an ultrasonic cleaner. Finally, 3 mL of methanol (CH3OH) was added as a hole sacrificial agent. After homogeneous mixing, the mixture was irradiated with a 300 W xenon lamp for 10 h while stirred. The resulting product was collected by centrifugation, washed alternately with water and ethanol, and then dried in a vacuum oven at 60 °C for 10 h to obtain the Cu / BVO catalyst with copper particles supported on the surface of BVO, denoted as Cu / BVO.

[0025] The following section describes the material characterization.

[0026] Morphology, structure, and elemental composition: The BVO and V prepared above were analyzed using a scanning electron microscope (SEM) (JSM-IT500HR, JEOL). Bi -BVO, Cu / BVO, Cu / V Bi -BVO was tested, and the results were as follows: Figure 1As shown, by Figure 1 It can be seen that the original BVO sample ( Figure 1 (a) It is mainly composed of relatively uniform blocky particles with clear particle boundaries, relatively complete crystal faces, and a relatively smooth overall surface, indicating that the prepared BVO has good crystallinity and a relatively regular surface structure; after DES treatment, V Bi -BVO sample ( Figure 1 (b) The Cu / BVO sample still maintains a similar morphology to BVO, and no obvious changes were observed; Figure 1 (c) The overall structure still retains a blocky granular morphology, with a relatively intact main structure and a roughened surface; Cu / V Bi -BVO sample ( Figure 1 (d) While maintaining the main block shape, a large number of small granular structures also appear on its surface.

[0027] X-ray energy dispersive spectroscopy (X-Max N 80, Oxford Instruments) was used to analyze Cu / V Bi -BVO was subjected to X-ray energy dispersive spectroscopy, and the results were as follows: Figure 2 As shown, Figure 2 It is Cu / V Bi X-ray energy spectrum of BVO Figure 2 In the image, (a) is the SEM image of the test area. (b), (c), (e), and (f) show that the sample mainly contains four elements: Bi, V, O, and Cu. The Bi, V, and O elements originate from the BiVO4 host material, while the Cu element comes from the subsequent photodeposition process, indicating that Cu species were successfully loaded onto V. Bi On the BVO surface, the mass fractions of Bi, O, V, and Cu are approximately 67.9%, 13.6%, 12.9%, and 5.5%, respectively. Figure 2 (d) In this case, the Cu content is close to the expected design value, indicating that the photodeposition method used can effectively achieve Cu loading on the sample surface.

[0028] BVO and V were analyzed using an X-ray diffractometer (D8 Advance, Bruker-AXS, Germany). Bi -BVO, Cu / BVO, Cu / V Bi -BVO underwent X-ray diffraction testing, and the results are as follows: Figure 3 As shown, Figure 3 The XRD patterns show that the diffraction peak positions of the four samples are basically the same, and all of them match the characteristic diffraction peaks of the standard card BiVO4#14-0688, indicating that the prepared samples have successfully formed a BiVO4 host crystal phase with good crystallinity.

[0029] Chemical composition: BVO and V were analyzed using an X-ray photoelectron spectroscopy system (ESCALAB 250Xi, Thermo Fisher Scientific, USA). Bi -BVO, Cu / BVO, Cu / V Bi -BVO was subjected to X-ray photoelectron spectroscopy, and the results were as follows: Figure 4 As shown, Figure 4 The X-ray photoelectron spectroscopy (XPS) shows the changes in the binding energy of each catalyst during the treatment process, including the Auger spectrum (…). Figure 4 (f) can prove that the surface copper mainly exists in the cost state +1 valence.

[0030] Absorption capacity: BVO and V were measured using a UV-Vis-NIR spectrophotometer (UV-2600, Shimadzu, Japan). Bi -BVO, Cu / BVO, Cu / V Bi -BVO was subjected to UV-Vis spectroscopy, and the results are as follows: Figure 5 As shown, Figure 5 The results show that the band gap of all samples did not change significantly, and the valence band position of the samples prepared in this invention (see...) Figure 5 (c) It can meet the basic thermodynamic conditions required for the initial oxidation and activation of methane, and provides the necessary band structure basis for the photocatalytic CH4 conversion reaction.

[0031] Charge separation capability: BVO and V were analyzed using a fluorescence spectrometer (F-7100, Hitachi, Japan). Bi -BVO, Cu / BVO, Cu / V Bi -BVO photoluminescence spectroscopy and time-resolved photoluminescence spectroscopy were performed, and the results are as follows: Figure 6 and Figure 7 As shown, by Figure 6 and Figure 7 It can be seen that Cu / V Bi -BVO exhibits the lowest PL intensity and the longest average fluorescence lifetime, indicating that this sample possesses optimal carrier separation and transport capabilities.

[0032] To verify whether DES treatment can effectively generate bismuth vacancies, electron paramagnetic resonance (EPR) spectra of the aforementioned BVO, BVO-DES-8H, and BVO-DES-24H samples were measured using a Bruker A300 spectrometer. The results are as follows: Figure 8 As shown, by Figure 8 It can be seen that as the degree of DES treatment increases, the concentration of defects on the sample surface continuously increases, indicating that DES treatment can effectively generate bismuth vacancies.

[0033] BVO and V were measured using a contact angle tester (H4ARKE-APCA, Beijing Hako).Bi -BVO, conduct contact angle testing, results as follows Figure 9 As shown, by Figure 9 It can be seen that V Bi The contact angle of the -BVO sample was 40.4°, indicating that its adsorption capacity for gaseous reactants was enhanced, which also means that its adsorption of CH4 was strengthened.

[0034] The Cu / V ratio was analyzed using a fluorescence spectrometer (F-7100, Hitachi, Japan). Bi -BVO and Cu / V Bi -BVO-P was subjected to photoluminescence spectroscopy testing, and the results are as follows: Figure 10 As shown, by Figure 10 It can be seen that Cu / V Bi -BVO-P has a significantly lower PL peak intensity than Cu / V. Bi -BVO. This result indicates that, after corona polarization, the recombination of photogenerated electrons and holes in the sample is further suppressed.

[0035] V was studied using an atomic force microscope (Multimode8, Bruker). Bi -BVO was characterized, and the results are as follows Figure 11 As shown, combining the amplitude and phase curves, it can be seen that V Bi -BVO4 samples have shown a relatively obvious local polarization response. This result indicates that the introduction of bismuth vacancies alters the local structural environment of BiVO4, disrupts the local lattice symmetry, and also causes a readjustment of the surrounding charge distribution.

[0036] Photocatalytic CH4 performance evaluation The photocatalytic performance of the materials was evaluated using the Labsolar-6A photocatalytic reaction system manufactured by Beijing Pofilai Technology Co., Ltd. A key advantage of this system is its integrated automatic gas sampling module, which can accurately collect gaseous products from the reactor according to a preset program and directly connect to an Agilent 8890 gas chromatograph for real-time online analysis, ensuring the accuracy and timeliness of qualitative and quantitative detection of gas components. 10 mg of photocatalyst (BVO, V...) was... Bi -BVO, Cu / BVO, Cu / V Bi -BVO and Cu / V BiThe deionized oxygen (BVO-P) was dispersed on a specially designed glass platform or filter paper (approximately 6 cm in diameter) and then placed on a triangular glass stand in the reactor (500 mL). 10 mL of deionized water was injected into the bottom of the reaction chamber. The system was then evacuated to 0.5 kPa (99.999%), controlled by a mass flow controller (LZB-3 WB, China). Bubbling was introduced into the reactor to raise the system pressure to 80 kPa. The system was then evacuated again, and this evacuation-purging process was repeated three times to remove as much air as possible. Finally, CH4 was slowly introduced to raise the pressure to 80 kPa. A 300 W xenon lamp was used as the light source, and a cooler (CNSHP DC-0506, China) was used for cooling water circulation to maintain the temperature at 5°C. The distance between the light source and the quartz window was kept constant at 10 cm. After the reaction, 1 mL of liquid sample was drawn using a syringe for subsequent analysis.

[0037] Both gaseous and liquid products were analyzed using an Agilent 8890 gas chromatograph. Gaseous products were directly injected into the chromatograph for detection. Liquid products, however, required hourly sampling, followed by dilution and injection into the chromatograph via an automated headspace sampler. The concentrations of the products were calculated using the external standard method. This involved first performing chromatographic detection using a standard substance of known concentration, plotting a standard curve of peak area versus concentration based on a correction factor, and then comparing the sample's peak position and area with the standard curve to determine the concentration. Results are as follows: Figure 12 As shown, (a) are different samples (1, 2, 3, 4, 5 represent BVO, V, and V, respectively). Bi -BVO, Cu / BVO, Cu / V Bi -BVO, Cu / V Bi (b) shows the results of -BVO-P), and (b) shows the Cu / V ratio for different Cu mass fractions. Bi The performance results of the photocatalytic CH4 conversion of -BVO are derived from Figure 12 (b) It can be seen that Cu / V Bi -BVO samples exhibited a significantly enhanced ethanol production capacity, with an ethanol production rate of approximately 19 μmol / g. -1 h -1 Cu / V after corona polarization treatment Bi The -BVO-P sample exhibited the highest C2H5OH formation rate, which was approximately 41 μmol / g. -1 h -1 5% Cu / V Bi -BVO, 10% Cu / V Bi -BVO and 15% Cu / V Bi The ethanol formation rate of -BVO is approximately 19.5 molg. −1 h −126.5 molg −1 h −1 and 33.5 μmolg −1 h −1 This indicates that as the Cu loading increases from 5% to 15%, the C2H content of the sample... S The OH formation rate gradually increased. However, when the Cu loading was further increased to 20%, the C2H5OH formation rate of the sample decreased to approximately 19 μmol / g. −1 h −1 This indicates that a higher Cu loading is not necessarily better; excessive loading can actually have an adverse effect on the reaction.

[0038] Unless otherwise specified, all technologies mentioned above refer to existing technologies.

[0039] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A method for preparing a bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles, characterized in that, Includes the following steps: 1) Bismuth vanadate was synthesized using a hydrothermal method; 2) Bismuth vacancies are introduced into the bismuth vanadate obtained in step 1) by using a deep eutectic solvent treatment method to obtain bismuth vanadate with bismuth vacancies; 3) Copper particles are loaded onto the surface of bismuth vanadate with bismuth vacancies obtained in step 2) using photodeposition to form a copper-supported composite catalyst; 4) The copper-supported composite catalyst obtained in step 3) is subjected to corona polarization treatment to obtain the final product.

2. The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported according to claim 1, characterized in that, The hydrothermal method in step 1) is as follows: Ammonium vanadate and bismuth nitrate pentahydrate are dissolved in nitric acid of equal concentration at a molar ratio of 1:0.9-1.1 to obtain a first solution and a second solution; then the second solution is slowly added dropwise to the first solution to obtain a stable and uniform yellow solution; then the pH value of the yellow solution is adjusted to 1.8-2.2 with ammonia water until an orange precipitate is formed to obtain a suspension slurry; then the suspension slurry is transferred to a Teflon-lined stainless steel high-pressure reactor and reacted at 180℃-220℃ for 20-28 hours, followed by cooling, filtration, separation, washing, and drying to obtain a bright yellow powder of bismuth vanadate.

3. The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported according to claim 1, characterized in that, The method for treating the eutectic solvent in step 2) is as follows: at room temperature, choline chloride and ethylene glycol are mixed in a molar ratio of 1:1.8-2.2 to obtain a eutectic solvent; then, the bismuth vanadate is immersed in the eutectic solvent and heated to 60℃-100℃ and held for 8-24 hours; then the product is centrifuged, washed and dried to obtain bismuth vanadate with bismuth vacancies.

4. The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported according to claim 1, characterized in that, The photodeposition method in step 3) is as follows: bismuth vanadate with bismuth vacancies is added to deionized water and mixed evenly; then copper nitrate trihydrate is added and mixed evenly, followed by methanol as a hole sacrificial agent and mixed evenly. Then, the mixture is irradiated with a 200-400W xenon lamp for 5-15 hours. The product is then centrifuged, washed, and dried to obtain a copper-supported composite catalyst. The mass ratio of bismuth vanadate with bismuth vacancies, copper nitrate trihydrate, and methanol is 1:0.1-0.3:10-15.

5. The method for preparing the bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported according to claim 1, characterized in that, The corona polarization treatment in step 4) is as follows: the powder of the copper-supported composite catalyst is evenly coated on the surface of the copper plate, an appropriate amount of alcohol is added for fixation, and then dried at room temperature to obtain the dried material. The dried material is then placed in a corona polarization device and subjected to corona polarization treatment at a voltage of 4-6kV for a polarization time of 1-4h to obtain the bismuth vanadate composite photocatalyst.

6. A bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles, characterized in that, The bismuth vanadate composite photocatalyst based on bismuth vacancies and copper particles supported is prepared using any one of claims 1-5.

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