Photochromic Mo-doped BiOCl ultrathin nanosheet enhanced ethyl benzene efficient photocatalysis C (sp3)-H oxidation

Abstract

The invention provides a bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies as well as a preparation method and application of the bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies. The structural formula of the bismuth oxychloride ultrathin nanosheet photochromic material is BiOCl, the surface of the bismuth oxychloride ultrathin nanosheet photochromic material is modified with polyvinylpyrrolidone and mannitol, and the preparation method of the bismuth oxychloride ultrathin nanosheet photochromic material comprises the following steps: adding the polyvinylpyrrolidone, the mannitol and a chlorine source into water, uniformly stirring and mixing, and then adding a water solution containing the chlorine source to obtain a mixed solution; and carrying out hydrothermal reaction on the obtained mixed solution, and then washing and drying to obtain the oxygen vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material. The Mo-doped BiOCl ultrathin nanosheet with the visible light response photochromic behavior, which is prepared by the preparation method disclosed by the invention, is used as a high-efficiency photocatalyst and is used for activating and selectively oxidizing C (sp3)-H of ethylbenzene. According to the Mo-doped BiOCl ultrathin nanosheet, rich oxygen vacancies are generated in the nanosheet, so that the BiOCl ultrathin nanosheet has a unique visible light response photochromic behavior and has an important application prospect in the fields of photocatalysis, carbon dioxide reduction and the like.

Description

Technical Field

[0001] This invention utilizes photochromic metal-doped BiOCl ultrathin nanosheets for C(sp) 3 The oxidation of H-H enabled the production of acetophenone with high added value under visible light irradiation, which belongs to the research field of semiconductor photocatalysis. Background Technology

[0002] By activating and oxidizing C(sp) in hydrocarbons 3 The C(sp)-H group of ethylbenzene forms high-value-added chemical or pharmaceutical intermediates, such as aldehydes, ketones, and epoxides, which are of great significance in the chemical industry and organic synthesis, and are gradually becoming a research hotspot in organic synthesis. Among them, the C(sp) group of ethylbenzene... 3 The activation and cleavage of acetophenone (C(sp)-H) bonds are quite difficult due to their high bond dissociation energy. Traditional acetophenone production processes involve high temperatures and pressures, which are environmentally unfriendly. In contrast, semiconductor photocatalysis technology can directly collect solar energy, generating photogenerated electron-hole pairs under light radiation, thereby activating O2 and C(sp)-H bonds. 3 These photocatalysts have attracted widespread attention due to their role in the catalytic oxidation of C(sp)-H. 3 The practical application of )-H is still subject to many limitations, such as low conversion rate, which is one of the important problems that need to be solved.

[0003] Among numerous photocatalysts, bismuth oxyhalides, especially bismuth oxychloride (BiOCl), with its unique two-dimensional layered structure composed of bismuth-oxygen layers and chloride ion layers, has attracted widespread attention in recent years due to its ability to shorten the transport distance of photogenerated carriers and generate abundant oxygen vacancies. However, the C(sp) of ethylbenzene remains a subject of considerable interest. 3 Studies on the photoactivation of )-H on BiOCl-based photocatalysts are almost nonexistent. For example, Li et al. developed a photochromic Bi2WO3 catalyst. 6-x Amorphous BiOCl nanosheets enhance charge separation efficiency and enable photogenerated holes to activate C(sp) of toluene. 3The desired target product is obtained by breaking down the α-H bond (X. Cao, Z. Chen, R. Lin, W.-C. Cheong, S. Liu, J. Zhang, Q. Peng, C. Chen, T. Han, X. Tong, Y. Wang, R. Shen, W. Zhu, D. Wang, Y. Li, A Photochromic Composite with Enhanced Carrier Separation for the Photocatalytic Activation of Benzylic C–HBonds in Toluene, Nat. Catal. 1 (2018) 704-710.). Furthermore, it has been reported that BOBr nanosheets achieve efficient separation of photogenerated carriers by capturing photogenerated holes under visible light during photochromism, thereby realizing the photocatalytic oxidation of ethylbenzene in an aqueous medium (X. Cao, A. Huang, C. Liang, HC Chen, T. Han, R. Lin, Q. Peng, Z. Zhuang, R. Shen, HM Chen, Y. Yu, C. Chen, Y. Li, Engineering Lattice Disorder on a Photocatalyst: Photochromic BiOBrNanosheets Enhance Activation of Aromatic CH Bonds via Water Oxidation, J.Am. Chem. Soc. 144 (2022) 3386-3397.). Inspired by these works, we attempted to achieve the photochromic effect of ethylbenzene C(sp) by endowing BiOCl nanosheets with abundant oxygen vacancies. 3Photo-oxidation of )-H. Recently, ultrathin nanosheets of BiOCl and BiOBr with rapid and reversible photochromism have been reported (Z. Yang, D. Wang, Y. Zhang, Z. Feng, L. Liu, W. Wang, Photoreductive BiOCl Ultrathin Nanosheets for Highly Efficient Photocatalytic Color Switching, ACS Appl. Mater. Interfaces. 12 (2020) 8604-8613, X. Zhang, Y. Zhang, Z. Feng, J. Zhao, Z. Yang, X. Wang, W. Wang, Self-Accelerating Photocharge Separation in BiOBr Ultrathin Nanosheets for Boosting Photoreversible Color Switching, Chem. Eng. J. 428 (2022).), but they still rely on high-energy ultraviolet light to drive the photochromic behavior and cannot make full use of visible light in sunlight.

[0004] Chinese patent document CN117619382A discloses a method for preparing an acetophenone catalyst by the oxidation of ethylbenzene without solvent. The material is prepared by the following method: a) a niobium source solution and a template agent solution are mixed and stirred under heating conditions, followed by a hydrothermal reaction to obtain a reaction product; the reaction product is then post-treated to obtain niobium oxide support powder; b) the niobium oxide support powder is dispersed in water, and then PdCl₂ solution and urea are added while stirring. The resulting precipitate is calcined to obtain a Pd / CNb₂O₅ catalyst. The niobium oxide support powder prepared by this method is insoluble in water and poorly soluble in acids, which limits its use in certain chemical reactions and applications. Furthermore, the properties of the PdCl₂ solution used in the synthesis process may be unstable under certain storage conditions, leading to easy decomposition or deterioration.

[0005] Therefore, it is necessary to develop visible light-responsive photochromic BiOCl ultrathin nanosheets for efficient photocatalytic oxidation of C(sp) 3 )-H has high practical application value. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the purpose of this invention is to develop ultrathin Mo-doped BiOCl nanosheets with blue light-responsive photochromic behavior for the photocatalytic oxidation of C(sp) of ethylbenzene. 3Efficient preparation of acetophenone using )-H. Mo in BiOCl ultrathin nanosheets under visible light irradiation. 6+ Reduced to Mo by photogenerated electrons 5+ Photochromic behavior occurs. The photochromic effect induces Mo... 6+ / Mo 5+ As an electron-trapping center, it captures photogenerated electrons, significantly improving the separation and transfer efficiency of photogenerated charges, thereby promoting the activation of ethylbenzene to benzyl radicals by photogenerated holes. Furthermore, the abundant oxygen vacancies generated by the 2D structure in the Mo-doped BiOCl ultrathin nanosheets serve as active sites, promoting O2 adsorption and activation to O2. •- Therefore, Mo-doped BiOCl ultrathin nanosheets exhibit excellent photocatalytic activity and stability in the conversion of ethylbenzene to acetophenone.

[0007] The technical solution of the present invention is as follows:

[0008] A bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies, with the structural formula BiOCl, wherein the surface of the bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies is modified with polyvinylpyrrolidone and mannitol; the size of the bismuth oxychloride ultrathin nanosheet photochromic material is 13-25 nm and the thickness is 1.5-2.9 nm.

[0009] To achieve the above-mentioned invention and solve the problems existing in the prior art, the technical solution adopted by the present invention is as follows: using Bi(NO3)3·5H2O and BiCl3 as bismuth sources, NaCl, KCl and LiCl as chlorine sources, sodium molybdate, molybdenum chloride and molybdenum powder as precursors, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA) and mannitol as ligands, and deionized water, ethanol, ethylene glycol and polyethylene glycol as solvents, Mo-doped BiOCl ultrathin nanosheets were synthesized by a simple hydrothermal method. According to the present invention, the preparation method of the above-mentioned oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material includes the following steps:

[0010] 0.6 g mannitol and 0.6 g polyvinylpyrrolidone were dissolved in 30 mL H2O under magnetic stirring. Then, 0.48 g Bi(NO3)3·5H2O, a certain volume of sodium molybdate aqueous solution (0.4 M), and 5 mL of NaCl aqueous solution (0.2 M) were added. After stirring continuously at room temperature for 10 min, the mixture was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene and heated at a certain temperature for 6 h. After naturally cooling to room temperature, the precipitate was collected by centrifugation, washed several times with acetone, ethanol, or water, and dried to obtain the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material.

[0011] According to a preferred embodiment of the present invention, the average molecular weight of the polyvinylpyrrolidone is 40,000-120,000; and the mass ratio of the polyvinylpyrrolidone to the bismuth source is 1-4:1.

[0012] According to a preferred embodiment of the present invention, the mass ratio of mannitol to bismuth source is 1-5:1.

[0013] According to a preferred embodiment of the present invention, the bismuth source is bismuth nitrate pentahydrate, bismuth chloride, bismuth carbonate, bismuth sulfate, or bismuth phosphate.

[0014] According to a preferred embodiment of the present invention, the mass ratio of the bismuth source to the volume of water is 1 g: 40-100 mL.

[0015] According to a preferred embodiment of the present invention, the chlorine source is sodium chloride, potassium chloride, or lithium chloride; and the concentration of the chlorine source in the aqueous solution containing the chlorine source is 0.1-0.6 mol / L.

[0016] According to a preferred embodiment of the present invention, the molar ratio of chlorine in the chlorine source to bismuth in the bismuth source is 1-4:1.

[0017] According to a preferred embodiment of the present invention, the hydrothermal reaction temperature is 130-170 °C and the hydrothermal reaction time is 4-7 h.

[0018] According to a preferred embodiment of the present invention, the washing is performed by centrifugal washing using a mixed solvent of anhydrous ethanol or acetone and deionized water; the volume ratio of anhydrous ethanol or acetone to deionized water in the mixed solvent is 4-5:1.

[0019] According to the present invention, the above-mentioned oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material is used in photochromic materials;

[0020] Furthermore, the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material has important application prospects in photocatalysis and carbon dioxide reduction.

[0021] The technical features and beneficial effects of this invention are as follows:

[0022] (1) Mo-doped BiOCl ultrathin nanosheets with visible light-responsive photochromic behavior were developed as a highly efficient photocatalyst for the activation and selective oxidation of C(sp) of ethylbenzene. 3 )-H. Mo induced by photochromic effect 6+ / Mo 5+ It can serve as an electron trapping center to capture and store photogenerated electrons, effectively improving the separation and transfer efficiency of photogenerated charges.

[0023] In the photocatalytic oxidation of ethylbenzene, the separated photogenerated holes effectively activated the C(sp) group of ethylbenzene.3 )-H generates benzyl radicals. Furthermore, the unique 2D layered structure in Mo-doped BiOCl ultrathin nanosheets generates abundant oxygen vacancies, which are beneficial for storage in Mo. 6+ / Mo 5+ The photogenerated electrons and oxygen vacancies on the surface absorb and activate O2. Therefore, benzyl radicals react with O2. •- The reaction generates peroxide radicals, ultimately producing the target product, acetophenone. Due to the photochromic effect and the presence of oxygen vacancies, the Mo-doped BiOCl ultrathin nanosheets exhibited an excellent photocatalytic rate of 8033 μmol·g⁻¹. -1 ·h -1 It is 9 times thicker than undoped BiOCl ultrathin nanosheets. This work lays the foundation for designing catalysts for ethylbenzene C(sp) 3 The activation and oxidation of H-H provide new strategies.

[0024] (2) C(sp) of hydrocarbons 3 )-H activation and oxidation produce high-value-added chemical or pharmaceutical intermediates, including aldehydes, ketones, and epoxides, which are crucial in the chemical industry and organic synthesis. In particular, acetophenone, produced by the oxidation of ethylbenzene, is a vital raw material for the production of pharmaceuticals, fragrances, cellulose ethers, resins, and other products, and thus has significant commercial value. Attached Figure Description

[0025] Figure 1 a is the X-ray diffraction (XRD) pattern of undoped BiOCl and Mo-doped BiOCl ultrathin nanosheets with different precursor Mo / Bi ratios in the examples; Figure 1 b is a transmission electron microscope (TEM) image of a typical Mo-doped BiOCl ultrathin nanosheet in the embodiment; Figure 1 c and d are bar charts showing the size and thickness distribution of the nanosheets in the examples.

[0026] Figure 2 a is a TEM image of the undoped BiOCl ultrathin nanosheets in the example; Figure 2 b is a histogram of the size distribution of undoped BiOCl ultrathin nanosheets in the examples. (The size range of the undoped BiOCl ultrathin nanosheets is 24-33 nm).

[0027] Figure 3 a is a TEM image of the undoped BiOCl ultrathin nanosheets in the example; Figure 3 b is a histogram of the thickness distribution of the undoped BiOCl ultrathin nanosheets in the examples. (The thickness of the undoped BiOCl ultrathin nanosheets ranges from 2.2 to 3.8 nm).

[0028] Figure 4a and b are the high-resolution XPS spectra of Mo 3d and O 1s of undoped BiOCl and typical Mo-doped BiOCl ultrathin nanosheets in the examples; Figure 4 c shows the ESR spectra of undoped BiOCl and typical Mo-doped BiOCl ultrathin nanosheets in the examples; Figure 4 d represents the UV-Vis diffuse reflectance absorption spectra of undoped BiOCl and Mo-doped BiOCl ultrathin nanosheets with different precursor Mo / Bi ratios in the examples.

[0029] Figure 5 a and b are high-resolution XPS spectra of Mo 3d (a) and O 1s (b) of Mo-doped BiOCl ultrathin nanosheets before and after blue light irradiation in the examples.

[0030] Figure 6 a and b are the UV-Vis diffuse reflectance absorption spectra in the examples showing the coloring process of Mo-doped BiOCl ultrathin nanosheets under blue light irradiation in water (a) and ethylbenzene:acetonitrile (2:1) (b); Figure 6 c is the UV-Vis diffuse reflectance absorption spectrum in the example showing the coloring process of undoped BiOCl ultrathin nanosheets in water under blue light irradiation.

[0031] Figure 7 a represents the change in the yield of ethylbenzene to acetophenone with blue light irradiation time in different catalysts in the examples; Figure 7 b is a comparison of the yield and photocatalytic performance of ethylbenzene to acetophenone in different catalysts in the examples.

[0032] Figure 8 a is a free radical capture experiment under standard conditions in the embodiment; Figure 8 b is the ESR diagram of undoped BiOCl and Mo-doped BiOCl ultrathin nanosheets under blue light irradiation in the presence of O2 and DMPO in the examples.

[0033] Figure 9 This study investigates the mechanism of photocatalytic oxidation of ethylbenzene using Mo-doped BiOCl ultrathin nanosheets in the embodiments. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments.

[0035] In addition, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; and unless otherwise specified, the reagents and materials are commercially available.

[0036] Example

[0037] (1) Dissolve 0.6 g mannitol and 0.6 g polyvinylpyrrolidone in 30 mL H2O under magnetic stirring, then add 0.48 g Bi(NO3)3·5H2O, a certain volume of sodium molybdate aqueous solution (0.4 M) and 5 mL NaCl aqueous solution (0.2 M). Stir continuously for 10 min at room temperature.

[0038] (2) Transfer the mixed solution from step (1) to a 50 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and heat it at a certain temperature for 6 h.

[0039] (3) After the reaction solution obtained in step (2) is naturally cooled to room temperature, the precipitate is collected by centrifugation, washed several times with acetone, ethanol or water, and dried to obtain the photochromic material of bismuth oxychloride ultrathin nanosheets rich in oxygen vacancies. Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 10% were labeled as typical samples.

[0040] (4) Add 3 mL of ethylbenzene and 10 mg of photocatalyst to a quartz sand tube. Before illumination, stir the resulting mixture for 0.5 hours to maintain adsorption-desorption equilibrium and fully dissolve the oxygen in the solution. Then, under oxygen conditions, use a 405 nm LED lamp (100 mW / cm²) 2 The mixture was irradiated at room temperature for 6 hours. The final product, acetophenone, was obtained.

[0041] The X-ray diffraction pattern of the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material prepared in this embodiment is as follows: Figure 1 As shown in a, Figure 1 Image a shows the XRD pattern of BiOCl ultrathin nanosheets synthesized with a Mo / Bi precursor ratio of 10%, clearly revealing the tetragonal phase structure of BiOCl (a = 3.891 Å, c = 7.369 Å). No peaks for ionic oxides were observed, likely due to the low Mo content. Figure 1 b is a typical transmission electron microscope (TEM) image of Mo-doped BiOCl ultrathin nanosheets, showing that the sample is composed of small nanosheets with a size of 13-25 nm. Figure 1 c shows that the sample is composed of small nanosheets with a size of 13-25 nm; Figure 1 The thickness of the nanosheets can be calculated to be 1.5-2.9 nm, confirming the ultrathin structure of the nanosheets.

[0042] In contrast, the tetragonal phases of undoped and Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 5% are consistent with typical samples. Figure 1a). Furthermore, with the increase of Mo ion loading, the diffraction peak intensity of the BiOCl ultrathin nanosheets gradually decreased, indicating a decrease in the crystallinity of the sample, which is consistent with the TEM results. Figure 2 and Figure 3 This may be attributed to molybdenum ions reducing the particle size of the nanosheets or increasing the microstructure distortion of the nanosheets.

[0043] Figure 4 This confirms the successful doping of Mo in the nanosheets. The two strong peaks at 235.10 and 231.97 eV in the Mo 3d XPS spectrum of the Mo-doped BiOCl ultrathin nanosheets correspond to Mo... 6+ Mo3d 3 / 2 and Mo3d 5 / 2 The signal peaks at 234.00 and 230.90 eV, and the two weak peaks at 234.00 and 230.90 eV, are attributed to the partial loss of oxygen atoms in the Mo signal. 5+ The undoped sample did not show a peak for Mo. Figure 4 As shown in b, the O 1s XPS plot of the Mo-doped BiOCl ultrathin nanosheets yielded three peaks from the Gaussian function, located at 529.50, 530.86, and 532.06 eV, respectively. These peaks are attributed to adsorbed oxygen from Bi-O bonds, oxygen atoms surrounding oxygen vacancies, and hydroxyl groups or O2 molecules. We further investigated the oxygen vacancy content using ESR characterization, such as... Figure 4 As shown in Figure c, Mo-doped BiOCl ultrathin nanosheets (10%) exhibit a strong ESR peak at g=2.00, attributed to the presence of oxygen vacancies, consistent with XPS results. The increased intensity of the ESR peak at g=2.00 compared to undoped BiOCl further confirms that molybdenum doping promotes the increase of a small number of oxygen vacancies, consistent with XPS findings. Figure 4 As can be seen from d, Mo ion doping causes the absorption to redshift to the visible light region of 452 and 478 nm, with the Mo / Bi precursor ratios being 5% and 10%, respectively.

[0044] Figure 5 a indicates that Mo under blue light irradiation 6+ Species are reduced to Mo by photogenerated electrons 5+ Compared to the initial Mo-doped BiOCl ultrathin nanosheets, the Mo 3d XPS images after blue light irradiation show that Mo... 5+ 3D 3 / 2 The binding energy of Mo decreased from 235.10 eV to 235.00 eV. 5+ 3D 5 / 2 The binding energy decreased from 231.97 eV to 231.87 eV, a decrease of 0.10 eV. Figure 5As can be seen from b, the O 1s XPS plot of the Mo-doped BiOCl ultrathin nanosheets shows that the oxygen index peak in the Bi-O bond at 529.52 eV shifted by 0.10 eV, which is due to the increase in oxygen vacancies.

[0045] The milky white hybrid dispersion of Mo-doped BiOCl ultrathin nanosheets turns light blue under blue light irradiation, as... Figure 6 As shown in Figure a, after approximately 10 s of blue light irradiation, the diffuse absorption spectrum of the Mo-doped BiOCl ultrathin nanosheet aqueous dispersion gradually increased in the visible light region of 450-800 nm. Interestingly, when the Mo-doped BiOCl ultrathin nanosheets were dispersed in a mixed organic solvent ethylbenzene:acetonitrile (2:1), more significant photochromic behavior was observed. Figure 6 b). In contrast, the undoped BiOCl ultrathin nanosheet aqueous dispersion exhibited negligible photochromic properties under blue light irradiation, due to... Figure 6 c shows that Mo ion-doped ultrathin nanosheets can significantly improve photochromic properties.

[0046] like Figure 7 As shown in figure a, the time-transformation curves indicate that a rapid acetophenone production rate of 8033 μmol·g⁻¹ was observed within 6 h for typical Mo-doped ultrathin nanosheets. -1 ·h -1 .Depend on Figure 7 As can be seen from b, the Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 5% provide 5500 μmol·g. -1 ·h -1 The acetophenone production rate was more than six times that of undoped BiOCl. In particular, Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 10% exhibited the highest acetophenone yield (8033 μmol·g⁻¹). -1 ·h -1 The molybdenum ion doping rate was nine times that of the undoped BiOCl sample, indicating a significant improvement in photocatalytic activity. Furthermore, increasing the Mo / Bi precursor ratio to 15% led to saturation of the acetophenone formation rate from the Mo-doped BiOCl ultrathin nanosheets.

[0047] Depend on Figure 8 As can be seen from a and b, the photochromic effect induces Mo... 6+ / Mo 5+ As an electron-capturing center, it captures photogenerated electrons, thereby significantly improving the separation and transfer efficiency of photogenerated charges. Subsequently, photogenerated holes activate the C(sp) group of ethylbenzene. 3 )-H generates benzyl radicals. Simultaneously, oxygen vacancies in the BiOCl ultrathin nanosheets serve as active sites for O2 adsorption, through the interaction of oxygen vacancies and Mo... 6+ / Mo5+ Stored photogenerated electrons promote the activation of O2 to form O2 •- The final product is acetophenone. The excellent photocatalytic activity is attributed to the photochromic effect, which promotes the separation of photogenerated charges.

[0048] Based on various characterization and experimental results, the photochromic effect of Mo-doped BiOCl ultrathin nanosheets plays a crucial role in the photocatalytic oxidation of ethylbenzene to acetophenone. A reasonable photocatalytic mechanism is proposed as follows: Mo-doped BiOCl ultrathin nanosheets generate photogenerated electrons and holes under blue light irradiation (…). Figure 9 ).

[0049] It can be concluded that the enhanced catalytic activity of Mo-doped BiOCl ultrathin nanosheets is due to the photochromic effect induced by Mo. 6+ / Mo 5+ It can act as an electron trapping center to capture photogenerated electrons, effectively improving the separation efficiency of photogenerated charges.

[0050] Comparative Example 1

[0051] A method for preparing bismuth oxychloride material, as described in Example 1, involves changing the molar amount of sodium molybdate under the same conditions to prepare Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 5%.

[0052] Comparative Example 2

[0053] A method for preparing bismuth oxychloride material, as described in Example 1, involves changing the molar amount of sodium molybdate under the same conditions to prepare undoped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 5%.

[0054] Comparison of Comparative Example 1 and the Examples shows that Mo-doped BiOCl ultrathin nanosheets with a Mo / Bi precursor ratio of 10% exhibit the highest acetophenone yield (8033 μmol·g). -1 ·h -1 The acetophenone generation rate of Mo-doped BiOCl ultrathin nanosheets was 9 times that of the undoped BiOCl sample. Furthermore, by further increasing the Mo / Bi precursor ratio to 15%, the acetophenone generation rate of Mo-doped BiOCl ultrathin nanosheets tended to saturate.

[0055] As can be seen from the comparison between Comparative Example 2 and the Examples, the improved catalytic activity of Mo-doped BiOCl ultrathin nanosheets is due to the photochromic effect induced by Mo. 6+ / Mo 5+ It can act as an electron trapping center to capture photogenerated electrons. Furthermore, the ultrathin 2D structure of Mo-doped BiOCl ultrathin nanosheets generates abundant oxygen vacancies, which is beneficial for storage in Mo. 6+ / Mo 5+The photogenerated electrons and oxygen vacancies on the surface absorb and activate O2. Therefore, benzyl radicals react with O2. •- The reaction generates peroxy radicals, which in turn produce the final target product, acetophenone.

Claims

1. A bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies, characterized in that, The bismuth oxychloride ultrathin nanosheet photochromic material has the structural formula BiOCl. The surface of the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material is modified with polyvinylpyrrolidone and mannitol. The size of the bismuth oxychloride ultrathin nanosheet photochromic material is 13-25 nm and the thickness is 1.5-2.9 nm.

2. The preparation method of the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 1, comprising the following steps: Polyvinylpyrrolidone, mannitol, and a chlorine source were added to water and stirred until well mixed. Then, an aqueous solution containing the chlorine source was added to obtain a mixed solution. The resulting mixed solution was subjected to a hydrothermal reaction, followed by washing and drying to obtain a bismuth oxychloride ultrathin nanosheet photochromic material rich in oxygen vacancies.

3. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The average molecular weight of the polyvinylpyrrolidone is 40,000-120,000; the mass ratio of the polyvinylpyrrolidone to the bismuth source is 1-4:

1.

4. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The mass ratio of mannitol to bismuth source is 1-5:

1.

5. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The bismuth source is bismuth nitrate pentahydrate, bismuth chloride, bismuth carbonate, bismuth sulfate, or bismuth phosphate; the mass ratio of the bismuth source to the volume of water is 1 g: 40-100 mL.

6. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The chlorine source is sodium chloride, potassium chloride, or lithium chloride; the concentration of the chlorine source in the aqueous solution is 0.1-0.6 mol / L.

7. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The molar ratio of chlorine in the chlorine source to bismuth in the bismuth source is 1-4:

1.

8. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The hydrothermal reaction temperature is 130-170 ℃, and the hydrothermal reaction time is 4-7 h.

9. The method for preparing the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 2, characterized in that, The washing process involves centrifugal washing using a mixed solvent of anhydrous ethanol or acetone and deionized water; the volume ratio of anhydrous ethanol or acetone to deionized water in the mixed solvent is 4-5:

1.

10. The application of the oxygen-vacancy-rich bismuth oxychloride ultrathin nanosheet photochromic material according to claim 1, characterized in that, It has important application prospects in fields such as photocatalysis and carbon dioxide reduction.

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