F, Application of Pd-modified single-crystal BiVO4 photocatalyst in photocatalytic degradation of glyphosate and synergistic production of H2O2

Abstract

The application provides an F, Pd modified single crystal BiVO4 photocatalyst and an application of the photocatalyst in photocatalytic degradation of glyphosate and synergistic production of H2O2. Single crystal BiVO4 powder is dispersed in a deionized water solution to prepare a suspension; a fluoride solution is added to the suspension, and the mixture is stirred under light irradiation for a certain time, washed and dried to obtain F ‑ modified photocatalyst (BiVO4-F-110) on a (110) crystal plane of the single crystal BiVO4 which is rich in photo holes; the BiVO4-F-110 is dispersed into a methanol water solution, a certain amount of a palladium chloride water solution is added, Ar is continuously introduced, dissolved O2 in the suspension is removed, and then the mixture is treated under light irradiation under stirring; after the light irradiation, the obtained precipitate is washed and dried to obtain the photocatalyst. Selective modification of F ions on the hole-rich crystal plane of the single crystal bismuth vanadate can promote the adsorption of glyphosate and effectively capture photo-generated holes, and the Pd loading on the (010) crystal plane can effectively enhance the O2 reduction to produce H2O2, thereby realizing the synergistic effect of pollutant degradation and H2O2 synthesis.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic material preparation and environmental remediation technology, specifically relating to a single-crystal BiVO4 photocatalyst with selective crystal facet modification and its preparation method. This catalyst selectively modifies the single-crystal bismuth vanadate with F ions via photo-induced modification on the hole-rich (110) crystal facet to promote the photogenerated hole oxidation and degradation of glyphosate. Simultaneously, it selectively loads Pd nanoparticles on the electron-rich (010) crystal facet to enhance O2 reduction to generate H2O2, achieving efficient synergistic pollution control and the synthesis of the green chemical H2O2. Background Technology

[0002] Glyphosate, one of the most widely used herbicides globally, poses a serious threat to the ecological environment and human health due to its residual effects. Compared to traditional advanced oxidation methods such as Fenton oxidation, adsorption, and ozone oxidation, emerging photocatalysis technologies utilize photocatalysts to activate molecular oxygen or H2O to form reactive oxygen species, converting solar energy into chemical energy to promote pollutant degradation. However, traditional single photocatalysts generally suffer from high carrier recombination rates, weak interfacial interactions with pollutant molecules, and low reaction efficiency. Single-crystal BiVO4 has been widely studied due to its suitable band structure, which effectively utilizes visible light absorption; and its excellent crystal facets effectively prevent bulk recombination of photogenerated carriers, achieving spatial separation. However, pure BiVO4 crystals are composed of Bi-O tetrahedra and VO octahedra. The surface metals (Bi and V) form covalent bonds with oxygen, resulting in a lack of effective catalytic active sites on the surface, leading to weak interfacial adsorption of H2O and oxygen molecules. Typically, modification with noble metals (such as Pd, Pt, Au, etc.) can effectively improve the efficiency of O2 reduction to H2O2, but using small alcohol molecules as sacrificial agents to capture photogenerated holes leads to a decrease in the utilization efficiency of the photocatalytic reaction; while using anionic modification (such as F... - While surface modification can modulate surface properties to some extent and improve the adsorption and activation of H2O, single modification cannot simultaneously achieve the synergistic effect of H2O2 generation and pollutant degradation. Therefore, developing a BiVO4 photocatalyst with selectively modified crystal faces that combines efficient H2O2 synthesis and glyphosate degradation capabilities has significant application value. Summary of the Invention

[0003] This invention addresses the problems of low carrier utilization efficiency, weak interfacial interaction between O2 molecules and the photocatalyst, poor glyphosate degradation efficiency, and insufficient H2O2 yield in existing BiVO4 photocatalysts. It provides a photo-induced synthesis of a Pd-010-BiVO4-F-110 photocatalyst with selectively modified crystal planes. - Selective modification of its hole-rich (110) crystal facets enhances glyphosate adsorption and oxidation, while metal Pd nanoparticles modify its electron-rich (010) crystal facets to promote O2 reduction to generate H2O2, thereby achieving synergistic effect.

[0004] A method for preparing F and Pd modified single-crystal BiVO4 photocatalysts, comprising the preparation of single-crystal BiVO4 photocatalysts with selective crystal plane modification, namely Pd-010-BiVO4-F-110, with single-crystal BiVO4 as the main body, and its (110) crystal plane modified by F - BiVO4-F-110 was modified to form a structure with Pd nanoparticles loaded on its (010) crystal plane; the amount of F ions modified was 0.01~10 wt% of the mass of BiVO4, and the amount of Pd loaded was 0.01~5 wt%. The method steps included the following:

[0005] (1) Disperse single-crystal BiVO4 powder in an aqueous solution to obtain a uniformly dispersed suspension;

[0006] (2) Add an appropriate amount of F ion source solution to the suspension obtained in step (1) and stir for a certain time under light irradiation;

[0007] (3) After the light exposure in step (2) is completed, the precipitate is washed and dried to obtain F. - A photocatalyst modified on the photo-hole plane of single-crystal bismuth vanadate, namely BiVO4-F-110 photocatalyst;

[0008] (4) Disperse the BiVO4-F-110 photocatalyst prepared in step (3) into a methanol aqueous solution, add a certain amount of palladium source solution, continuously introduce Ar to remove the dissolved O2 in the suspension, and then perform phototreatment under stirring conditions.

[0009] (5) After the light irradiation in step (4), the precipitate is washed and dried to obtain single crystal bismuth vanadate with hole-plane selective modification F and electron-plane modification Pd, namely Pd-010-BiVO4-F-110 photocatalyst.

[0010] The preparation method of single-crystal BiVO4 powder is as follows: using bismuth nitrate and ammonium metavanadate as raw materials, Bi(NO3)3·5H2O and NH4VO3 are dissolved in dilute nitric acid, the pH is adjusted to 2 with ammonia water, and the single-crystal BiVO4 bulk is directly synthesized by hydrothermal reaction at 180 ℃ for 24 h. The thickness is 0.5-1 μm and the diameter is 1-3 μm.

[0011] The F ion source is an organic fluoride that can dissociate F ions in aqueous solution (triethylamine trihydrofluoric acid ((C2H5)3N(HF)3), tetrabutylammonium fluoride ((n-C4H9)4NF), tetramethylammonium fluoride (C4H)3, etc. 12 FN), tetraethylammonium fluoride (C8H) 24 The F ion source solution contains inorganic F salts (NH4HF2, NH4F, HF, KF, etc.) and has a concentration of 0.01~0.5 M.

[0012] In step (2), the photo-irradiation reaction is carried out for 0.1-8 h, and the light source used for irradiation should be any one of xenon lamp, mercury lamp, metal halide lamp or LED lamp capable of producing light in the range of (200-520 nm). The drying temperature of the obtained product is 40-80 ℃; the drying time is 0.5-12 h.

[0013] In step (4), the palladium source includes any one of the soluble Pd salts such as PdCl2, Pd(NO3)2, PdSO4, Pd(OAc)2, Na2PdCl4, K2PdCl6, and (NH4)2PdCl6, and the palladium loading is 0.01~5 wt%.

[0014] In step (4), the photo-irradiation reaction is carried out for 0.1-8 h, and the light source used for irradiation should be able to produce any one of xenon lamps, mercury lamps, metal halide lamps or LED lamps in the range of (200-520 nm). The obtained product is dried at a temperature of 40-80 ℃ for 0.5-12 h.

[0015] The precipitate obtained from step (5) is filtered and separated, washed 3-5 times with deionized water and anhydrous ethanol respectively, and dried in an oven at 40-80 ℃ to obtain Pd-010-BiVO4-F-110 photocatalyst.

[0016] This invention also provides a single-crystal bismuth vanadate photocatalyst with hole-plane selective modification of F and electron-plane modification of Pd, prepared by the method described above. The bismuth vanadate is a hole-rich (110) plane selectively modified with F. - Pd nanoparticles are loaded on electron-rich crystal planes (010).

[0017] Another technical solution of the present invention is the application of the single-crystal bismuth vanadate hole-plane selectively modified F and electron-plane modified Pd photocatalyst in catalyzing the reduction of O2 to H2O2.

[0018] Another technical solution of the present invention is the application of the single-crystal bismuth vanadate hole-plane selectively modified F and electron-plane modified Pd photocatalyst in the catalytic production of H2O2 to degrade glyphosate.

[0019] Another technical solution of the present invention is to apply the single-crystal bismuth vanadate hole-plane selectively modified F and electron-plane modified Pd photocatalyst to photocatalytic oxygen reduction to generate H2O2 in a solution containing glyphosate.

[0020] The photocatalytic activity of Pd-010-BiVO4-F-110 photocatalyst was tested by performing photocatalytic oxygen reduction to H2O2 in a solution containing glyphosate. The specific experimental procedure is as follows: 20 mg of Pd-010-BiVO4-F-110 photocatalyst was dispersed in a beaker containing a 10-100 mg / L glyphosate solution. The light source was a 50 mW cm⁻¹ xenon lamp equipped with a filter (to filter out ultraviolet light with wavelengths less than 420 nm). -2 Every 5 minutes, 5 mL of the reaction solution was taken for filtration and separation. 2 mL of the solution was then added to 0.05 mol / L potassium titanium oxalate for a colorimetric reaction for 30 minutes. The concentration of H₂O₂ generated in the reaction solution at 385 nm was measured using a UV-Vis absorption spectrometer. Additionally, 200 μL of ammonium molybdate (25 g / L) and 300 μL of ascorbic acid (20 g / L) were added sequentially to 300 μL of the separated reaction solution for a colorimetric reaction for 10 minutes. The concentration of PO₄⁻ generated after glyphosate degradation in the reaction solution was then measured at 710 nm. 3- The concentration.

[0021] The basic principle of this synthesis method is as follows: Under illumination, a decahedral single-crystal BiVO4 is photoexcited, and the generated photogenerated carriers, under the influence of the interfacial electric field, concentrate photoelectrons on the (010) crystal plane, making this crystal plane negatively charged, while photoholes concentrate on the (110) crystal plane, causing this crystal plane to be positively charged. The added F ions, under electrostatic interaction, are mainly adsorbed on the (110) crystal plane of the single-crystal BiVO4. On the other hand, palladium ions on the surface of the single-crystal BiVO4 are concentrated on its (010) crystal plane through electrostatic interaction, and are reduced by photoelectrons concentrated on this crystal plane, aggregating to form metal Pd nanoparticles. By controlling the added F... - By adjusting the palladium ion concentration, the modification amounts of F and Pd on the surface of single-crystal BiVO4 can be effectively controlled. A simple photo-induced method was used to selectively modify different crystal planes of BiVO4 with F ions and metallic Pd nanoparticles. The resulting Pd-010-BiVO4-F-110 photocatalyst effectively enhances the interfacial adsorption of reactant molecules, achieving spatially separated redox reactions. This overcomes the low efficiency of photogenerated carrier interfacial reactions during the use of pure BiVO4 photocatalysts, synergistically achieving oxygen reduction to H2O2 production and efficient degradation of glyphosate.

[0022] Based on the above analysis, the technical solution to achieve the objective of this invention is:

[0023] Microstructure characterization methods for Pd-010-BiVO4-F-110 photocatalyst: Morphology and structure were observed using field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM); crystal structure and composition of the sample were characterized by X-ray diffraction (XRD); surface structure features of the sample were observed using Fourier transform infrared spectroscopy (FTIR); and the diffuse reflectance absorption spectrum of the sample was measured using ultraviolet-visible spectroscopy (UV-2600).

[0024] Selective modification of F ions on the hole-rich crystal facets of single-crystal bismuth vanadate promotes glyphosate adsorption and effectively captures photogenerated holes. Pd-supported (010) crystal facets effectively enhance O2 reduction to H2O2, thereby achieving synergistic effects on GP pollutant degradation and H2O2 synthesis. The photocatalytic degradation efficiency for glyphosate reaches over 85%, preferably over 90%. Attached Figure Description

[0025] Figure 1 The XRD patterns are those of the BiVO4, BiVO4-F-110, Pd-010-BiVO4, and Pd-010-BiVO4-F-110 photocatalysts in Example 1.

[0026] Figure 2 The UV-vis spectra of the BiVO4, BiVO4-F-110, Pd-010-BiVO4 and Pd-010-BiVO4-F-110 photocatalysts in Example 1 are shown.

[0027] Figure 3 These are the FTIR spectra of the BiVO4, BiVO4-F-110, Pd-010-BiVO4, and Pd-010-BiVO4-F-110 photocatalysts in Example 1, where A represents wavelengths of 400-2000 cm⁻¹. 1 FTIR spectra in the range of 3000-4000 cm⁻¹ 1 FTIR spectra of the range.

[0028] Figure 4 These are SEM images of the BiVO4, BiVO4-F-110, Pd-010-BiVO4, and Pd-010-BiVO4-F-110 photocatalysts in Example 1.

[0029] Figure 5 These are HAADF-STEM and elemental surface scan images of the Pd-010-BiVO4-F-110 sample prepared in Example 1.

[0030] Figure 6The graph shows the H2O2 generation (A) and glyphosate degradation over time curves of BiVO4, BiVO4-F-110, Pd-010-BiVO4 and Pd-010-BiVO4-F-110 photocatalysts in Example 1 (B). Detailed Implementation

[0031] This invention utilizes a photo-induced modification method to selectively adsorb F ions on the (110) crystal facet of single-crystal BiVO4, enriched with photoelectrons, and then selectively modify metal Pd nanoparticles on the (010) crystal facet, thereby constructing a Pd-010-BiVO4-F-110 photocatalyst. The method begins by adding bright yellow BiVO4 powder to an aqueous solution, followed by the addition of a fluorine-containing solution. The mixture is then continuously stirred and irradiated. The resulting precipitate is washed and dried to obtain a photocatalyst (BiVO4-F-110) with selectively modified F ions on the (110) crystal facet of single-crystal BiVO4 enriched with photoelectrons. The obtained BiVO4-F-110 is then dispersed in a methanol aqueous solution, and a certain amount of palladium chloride solution is added. Under stirring conditions, metal Pd ions are induced to reduce and deposit on the (010) crystal facet of bismuth vanadate through photo-induced deposition. The precipitate is further washed and dried to obtain the Pd-010-BiVO4-F-110 photocatalyst.

[0032] Example 1

[0033] The preparation process of Pd-010-BiVO4-F-110 photocatalyst is as follows:

[0034] (1) Preparation of single-crystal BiVO4 photocatalyst: At room temperature, 7.2 mmol of bismuth nitrate and 7.2 mmol of ammonium metavanadate were dissolved in 20 mL of dilute nitric acid solution (2 mol / L). Then, the bismuth nitrate solution was added dropwise to the ammonium metavanadate solution under constant stirring. After mixing evenly, the pH of the above reaction solution was adjusted to 2 with ammonia water. The solution was then transferred to a hydrothermal reactor and placed at 180℃ for 24 h. The solution was washed three times with deionized water and ethanol to obtain decahedral single-crystal BiVO4.

[0035] (2) 0.1 g BiVO4 powder was added to a 0.01 mol / L tetrabutylammonium fluoride solution, and the mixture was continuously stirred and irradiated with light for 2 h. After washing and drying, F was obtained. - The photocatalytic material selectively adsorbed on the BiVO4(110) crystal plane is BiVO4-F-110. The F ion concentration is 0.01 mol / L.

[0036] (3) 100 mg of the prepared BiVO4-F-110 photocatalyst was added to 100 mL of methanol aqueous solution (10 vol%), followed by 100 μL of palladium chloride (0.1 mol / L) solution. After stirring until homogeneous, dissolved oxygen in the reaction system was continuously removed by purging with Ar. The system was then irradiated with a xenon lamp for 2 h. The product was washed three times with deionized water and anhydrous ethanol, respectively. Finally, it was dried at 60 °C for 12 h to obtain the Pd-010-BiVO4-F-110 photocatalyst. In addition, as a control, under the same experimental conditions, Pd-010-BiVO4 photocatalyst was obtained by replacing BiVO4-F-110 with single-crystal BiVO4 powder.

[0037] The photocatalytic activity of the single-crystal BiVO4, BiVO4-F-110, Pd-010-BiVO4, and Pd-010-BiVO4-F-110 photocatalysts prepared above was tested by photocatalytic oxygen reduction to H2O2 in a solution containing glyphosate. The specific experimental procedure is as follows: 20 mg of the photocatalyst was dispersed in a beaker containing a 10 mg / L glyphosate solution. The light source was a xenon lamp (100 mW cm⁻¹) equipped with a filter (to filter out ultraviolet light with wavelengths less than 420 nm). -2 Every 5 minutes, 5 mL of the reaction solution was taken for filtration and separation. 2 mL of the solution was then added to 0.05 mol / L potassium titanium oxalate to indicate the reaction for 30 minutes. The concentration of H₂O₂ generated in the reaction solution at 385 nm was measured using a UV-Vis absorption spectrometer. Additionally, 300 μL of the separated reaction solution was successively added to 200 μL ammonium molybdate (25 g / L) and 300 μL ascorbic acid (20 g / L) for a colorimetric reaction for 10 minutes. The production of PO₄⁻ from the photodegradation of glyphosate was then measured at 710 nm. 3- The concentration.

[0038] Figure 1 XRD patterns of different BiVO4 samples ( Figure 1 The terms BiVO4-F-110 and Pd-010-BiVO4-F-110 refer to steps 2 and 3 above, respectively. Figure 1 It can be observed that the XRD characteristic diffraction peaks of the pure BiVO4 photocatalyst match the standard card (PDF#14-0688) very well, indicating that the monoclinic phase BiVO4 is hydrothermally synthesized. After photo-induced F modification on its (110) crystal plane, its XRD characteristic peaks are significantly weakened, indicating that F... -The surface was successfully modified. Further observation revealed that after the metal Pd was modified on its (010) crystal plane, the XRD characteristic peaks of Pd-010-BiVO4 and Pd-010-BiVO4-F-110 photocatalysts showed the characteristic signal peak of metal Pd at 40.1, indicating the successful modification of the metal Pd nanoparticles on its surface, and thus proving the preparation of Pd-010-BiVO4-F-110.

[0039] Figure 2 UV-vis spectra of different BiVO4 photocatalysts. Figure 2 It can be seen that single-crystal BiVO4 exhibits an absorption edge at approximately 520 nm, demonstrating good visible light response absorption. Comparing BiVO4 and Pd-010-BiVO4 samples, and observing the Pd-010-BiVO4 and Pd-010-BiVO4-F-110 photocatalysts, it was found that the modification of the BiVO4 surface with F ions had no significant effect on its light absorption. The light absorption of Pd-010-BiVO4 and Pd-010-BiVO4-F-110 photocatalysts was significantly enhanced in the range of 520 nm to 800 nm, and the optical spectrum color of the samples changed significantly from bright yellow to yellow-green, indicating that the selective modification of the (010) crystal plane by the metallic Pd nanoparticles enhanced the visible light absorption of the BiVO4 photocatalyst to a certain extent, which contributes to the improvement of its photocatalytic performance.

[0040] Figure 3 FTIR spectra of different BiVO4 photocatalysts. Figure 3 As can be seen from A, all samples were at 728 and 1105 cm⁻¹. -1 Two distinct characteristic peaks appeared near the wavelength, corresponding to VO4 and VO4 respectively. 3- Symmetric and asymmetric stretching vibrations of the structure. Observation of BiVO4-F-110 and Pd-010-BiVO4-F-110 shows that after modifying the surface of BiVO4 photocatalyst with F ions, the 620 cm⁻¹... -1 The signal peak near the wavelength (Bi-O bond bending vibration) was significantly weakened, indicating a significant interaction between the F ions modified on the (110) crystal plane and BiVO4. Figure 3 In section B, comparing BiVO4 and Pd-010-BiVO4 photocatalysts, the BiVO4-F-110 and Pd-010-BiVO4-F-110 photocatalysts showed better performance at 3425 cm⁻¹. -1 The presence of characteristic signal peaks of the OH group of H2O molecules further indicates that the selective modification of F ions by the (110) crystal plane of BiVO4 helps to promote the adsorption and activation of water molecules through hydrogen bonding interactions.

[0041] Figure 4SEM images of different BiVO4 samples. Figure 4 A reveals that the pure BiVO4 sample has a smooth surface, a thickness of approximately 0.5-1 μm, and consists of individual cubic crystals approximately 1-3 μm in size, exhibiting a decahedral shape. The top and bottom two square faces correspond to the (010) crystal face, and the four surrounding trapezoidal faces correspond to the (110) crystal face. Through... Figure 4 As can be seen from B and C, after modifying its (110) crystal plane with F ions, its morphology and structure did not change significantly, and the amount of F ions modified was approximately 0.06 wt%. Observation Figure 4 Images D and E reveal that metallic Pd nanoparticles are clearly modified on the (010) crystal plane of BiVO4, with a Pd nanoparticle size of approximately 10-20 nm. Further observation... Figure 5 HAADF-STEM images and elemental surface scan images of Pd-010-BiVO4-F-110 samples A and B show that metallic Pd nanoparticles were successfully loaded onto the (010) crystal plane of BiVO4, while F element mainly modified the (110) crystal plane of BiVO4. These SEM and TEM results indicate the successful preparation of the Pd-010-BiVO4-F-110 photocatalyst.

[0042] Figure 6 The graphs show the changes in H2O2 production and glyphosate degradation concentrations for different BiVO4 samples after 120 min of light irradiation. Figure 6 A shows that the content of H2O2 generated by photocatalysis of single-crystal BiVO4 is 5.6 μmol. -1 After modification of its (110) crystal plane, the H2O2 production of F ions increased to 35.7 μmol. -1 This indicates that the modification with F effectively promotes the H2O oxidation reaction at the interface to a certain extent. When metallic Pd nanoparticles are modified on the BiVO4(010) crystal plane, the H2O2 generation amount of the Pd-010-BiVO4 photocatalyst is 1264.3 μmol. -1 In comparison, the H2O2 production of the Pd-010-BiVO4-F-110 photocatalyst reached 1785.1 μmol. -1 Further modifications to F improved its performance by 1.4 times. (Observation) Figure 6 B reveals that the photocatalytic degradation effects of BiVO4, BiVO4-F-110, Pd-010-BiVO4, and Pd-010-BiVO4-F-110 on glyphosate were 16.4%, 26.8%, 70.2%, and 89.9%, respectively. This indicates that the F-modified (110) crystal plane... -Hydrogen bonding can significantly improve the photocatalytic degradation efficiency of glyphosate by BiVO4, while metal Pd nanoparticles modified on the (010) crystal plane can effectively improve electron transfer efficiency and promote the reduction of O2 to H2O2.

[0043] Experiment Example 2

[0044] To examine the effect of different types of fluorides on the selective modification of F ions on the (110) crystal plane of single-crystal BiVO4 in the photoinduced process, other reaction conditions such as the concentration of F ions, the type of light source and the illumination time were the same as in Example 1. However, when the organofluoride tetrabutylammonium fluoride was replaced with triethylamine trihydrofluoric acid ((C2H5)3N(HF)3) or ammonium hydrogen fluoride (NH4HF2), the F ions in the reaction system could be selectively adsorbed on the (110) crystal plane of single-crystal BiVO4 that is rich in photoholes, forming a BiVO4-F-110 photocatalyst.

[0045] When the active ingredient is triethylamine trihydrofluoric acid ((C2H5)3N(HF)3), the Pd-010-BiVO4-F-110 photocatalyst achieves an oxygen reduction to H2O2 production of 1962.5 μmol. -1 The photocatalytic degradation efficiency of glyphosate was 94.4%.

[0046] When the hydrogen fluoride is ammonium bifluoride (NH4HF2), the amount of H2O2 produced by the Pd-010-BiVO4-F-110 photocatalyst that reduces oxygen reaches 1218.7 μmol. -1 The photocatalytic degradation efficiency of glyphosate was 73.7%.

Claims

1. A method for preparing an F- and Pd-modified single-crystal BiVO4 photocatalyst, characterized in that: The preparation steps of this photocatalyst are as follows: (1) Disperse single-crystal BiVO4 powder in an aqueous solution to prepare a suspension; (2) Add an appropriate amount of F ion source solution to the suspension obtained in step (1) and stir and mix under light; (3) After the light exposure in step (2) is completed, the precipitate is washed and dried to obtain F. - BiVO4-F-110 photocatalyst was formed by modifying the (110) crystal plane of single-crystal bismuth vanadate rich in photo-holes. (4) Disperse the BiVO4-F-110 photocatalyst prepared in step (3) into a methanol aqueous solution, add palladium source solution, continuously introduce Ar to remove dissolved O2 in the suspension, and then perform phototreatment under stirring conditions. (5) After the light irradiation in step (4), the precipitate is washed and dried to obtain the single crystal bismuth vanadate hole-face modified F and electron-face modified Pd photocatalyst Pd-010-BiVO4-F-110.

2. The method for preparing F and Pd modified single-crystal BiVO4 photocatalyst according to claim 1, characterized in that: The F ion source is an organic fluoride or an inorganic fluoride salt; the organic fluoride is selected from any one of triethylamine trihydrofluoric acid, tetrabutylammonium fluoride, tetramethylammonium fluoride, and tetraethylammonium fluoride; The inorganic fluoride salt is selected from NH4HF2, NH4F, HF or KF.

3. The method for preparing F and Pd modified single-crystal BiVO4 photocatalyst according to claim 2, characterized in that: The concentration of the F ion source solution is 0.01~0.5 M.

4. The method for preparing F and Pd modified single-crystal BiVO4 photocatalyst according to claim 1, characterized in that: In step (2), the light reaction lasts for 0.1-8 hours, and the light source used for the light is any one of xenon lamp, mercury lamp, metal halide lamp or LED lamp.

5. The method for preparing F and Pd modified single-crystal BiVO4 photocatalyst according to claim 1, characterized in that: In step (4), the palladium source includes soluble Pd salts from PdCl2, Pd(NO3)2, PdSO4, Pd(OAc)2, Na2PdCl4, K2PdCl6, and (NH4)2PdCl6, with a palladium loading of 0.01~5 wt%.

6. The method for preparing F and Pd modified single-crystal BiVO4 photocatalyst according to claim 1, characterized in that: In step (4), the light reaction lasts for 0.1-8 hours, and the light source is any one of xenon lamp, mercury lamp, metal halide lamp or LED lamp.

7. An F- and Pd-modified single-crystal BiVO4 photocatalyst, characterized in that: The bismuth vanadate prepared by the method according to any one of claims 1-6 is a hole-rich crystal plane (110) selectively modified F. - Pd nanoparticles are loaded on electron-rich crystal planes (010).

8. The application of the F and Pd modified single-crystal BiVO4 photocatalyst according to claim 7 in catalyzing the reduction of O2 to H2O2.

9. The application according to claim 8, characterized in that, Application of F and Pd modified single-crystal BiVO4 photocatalysts in the degradation of glyphosate during catalytic H2O2 production.

10. The application according to claim 9, characterized in that, The application of F and Pd modified single-crystal BiVO4 photocatalysts in the photocatalytic oxygen reduction to H2O2 generation in a solution containing glyphosate.

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