Ultrathin nanosheet sulfur-doped BiOCl photocatalyst with near-infrared light response as well as preparation method and application of ultrathin nanosheet sulfur-doped BiOCl photocatalyst

Abstract

The invention discloses a near-infrared light response ultrathin nanosheet sulfur-doped BiOCl photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of photocatalytic materials. The preparation method comprises the following technical steps: (1) preparing a BiOCl nanosheet; and (2) preparing the sulfur-doped BiOCl nanosheet. By adopting a secondary hydrothermal method and controlling the dosage of thioacetamide and BiOCl nanosheets, the prepared catalyst is an ultrathin nanosheet with uniform morphology, the average size is 70-120nm, the catalyst has light response in a near-infrared light region of 780-1200nm, the light absorption capacity of the catalyst is better, and near-infrared light response can be achieved. The catalyst is applied to catalytic degradation of ENR, the ENR degradation rate under visible light is 66.87%, and the degradation effect is good; under near-infrared light, the ENR degradation rate is 9.25%, and the degradation performance from zero to existence is achieved. The preparation method disclosed by the invention is simple, mild in condition, easy to control, low in raw material consumption, free of complex operations such as centrifugation, low in preparation cost and easy to popularize and apply.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic materials, and in particular relates to a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst and a preparation method and application thereof. Background Art

[0002] Enrofloxacin (ENR) is a common fluoroquinolone antibiotic widely used in human and animal medicine. However, since ENR can only be partially metabolized in humans or animals and has poor biodegradability, most of ENR is eventually discharged into the water environment. Even trace amounts of ENR in water can harm human health and aquatic ecosystems. Therefore, removing ENR from the water environment has become increasingly urgent, and it is necessary to develop an economical, efficient, and environmentally friendly ENR treatment technology.

[0003] Photocatalysis is considered to be a promising and sustainable pollutant removal technology, which can degrade or even mineralize pollutants into harmless CO2 and H2O under the stimulation of solar energy, which provides a new path for the treatment of antibiotic pollutants. However, most photocatalysts have a narrow light response range and cannot effectively absorb infrared light (near-infrared light accounts for about 50% of total solar energy), which seriously limits the utilization of sunlight and solar energy and has low quantum efficiency. In addition, the photocatalytic activity of most photocatalysts is far from satisfactory, mainly because of the high recombination rate of photoinduced carriers in semiconductor charge transport, that is, redox reactions on the surface. Therefore, it is of great significance to develop new photocatalytic materials with wide spectral response. In recent years, element doping has been widely used to improve the photocatalytic performance of BiOCl. BiOCl has good absorption only in the ultraviolet region. The introduction of non-metallic sulfur doping can produce localized energy levels and reduce the band gap of semiconductor materials to enhance visible light absorption and even reach near-infrared light response. Patent publication number CN 107999095 A discloses a method for preparing a sulfur-doped bismuth oxychloride powder photocatalytic material. The BiOCl precursor prepared by this method is large in size and has an uneven morphology. In the subsequent sulfur doping process, BiOCl is dissolved in a hydrochloric acid solution, a chlorine source is additionally introduced, and then a sulfur source is introduced, which is equivalent to a dissolution and reprecipitation process. In this process, the S doping is not uniform (the size and morphology of the electron microscope are not uniform enough), the light absorption capacity (shown by the light absorption spectrum) is not significantly improved, and although the size of the nanosheets has become smaller, they are still large and the morphology is uneven.

[0004] Based on the above, the present invention proposes a method for preparing a near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, in which a secondary hydrothermal method is used to uniformly dope S on the BiOCl nanosheets under high temperature and high pressure, while maintaining the morphology of the ultrathin BiOCl nanosheet precursor and reducing the average size, which can greatly enhance the light absorption capacity of the catalyst, improve the photogenerated electron-hole separation efficiency, enhance the transfer and separation of interfacial charges, and achieve degradation of ENR from zero to full under near-infrared light response. Summary of the invention

[0005] In view of the above problems, the present invention provides a near-infrared light responsive ultra-thin nanosheet sulfur-doped BiOCl photocatalyst and a preparation method and application thereof. By adopting a secondary hydrothermal method and controlling the amount of thioacetamide and BiOCl nanosheets, the prepared catalyst is an ultra-thin nanosheet with uniform morphology. The catalyst has good light absorption ability and can achieve near-infrared light response.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst comprises the following steps:

[0008] (1) Preparation of BiOCl nanosheets: bismuth nitrate pentahydrate, mannitol and polyvinyl pyrrolidone were added to water and stirred continuously at room temperature, and then a saturated sodium chloride solution was added. After stirring, the resulting mixed solution was placed in a hydrothermal reactor for hydrothermal reaction. After the reaction was completed, the mixture was naturally cooled, and the resulting product was washed and freeze-dried to obtain BiOCl nanosheets;

[0009] (2) Preparation of sulfur-doped BiOCl nanosheets: placing the BiOCl nanosheets prepared in step (1) in water and stirring to obtain a BiOCl dispersion; placing thioacetamide in water and stirring to obtain a thioacetamide solution; adding the thioacetamide solution to the BiOCl dispersion and stirring to obtain a mixed solution; placing the mixed solution in a hydrothermal reactor for a secondary hydrothermal reaction, cooling the mixture naturally after the reaction is completed, washing the obtained product and freeze-drying it to obtain an ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light.

[0010] Furthermore, in step (2), the molar ratio of the thioacetamide to the BiOCl nanosheets is 0.04-0.06:1, and the mass ratio is 1.5-2.3:130.

[0011] Furthermore, in step (2), the temperature of the hydrothermal reaction is 150-160° C., and the time is 5-6 hours.

[0012] Furthermore, in step (1), the mass ratio of the bismuth nitrate pentahydrate, mannitol and polyvinyl pyrrolidone is 1:0.4-0.6:0.3-0.5.

[0013] Furthermore, in step (1), the mass ratio of the bismuth nitrate pentahydrate to the saturated sodium chloride solution is 1 g: 1.5-3 mL.

[0014] Furthermore, in step (1), the temperature of the hydrothermal reaction is 150-160° C., and the time is 2.5-3 h.

[0015] A near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst prepared by the preparation method described above.

[0016] Furthermore, the structure of the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst is an ultrathin nanosheet with uniform morphology, an average size of 70 to 120 nm, and a light response in the near-infrared light region of 780 to 1200 nm.

[0017] An application of the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst as described above in the photocatalytic degradation of enrofloxacin.

[0018] Furthermore, the degradation rate of enrofloxacin by the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst is 66.5-67.0 after 100 minutes of irradiation under visible light, and the degradation rate of enrofloxacin by the near-infrared light is 9.2-9.3% after 100 minutes of irradiation under near-infrared light.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0020] 1. The present invention synthesizes BiOCl nanosheets in a primary hydrothermal reaction, and sulfur-dopes the BiOCl nanosheets in a secondary hydrothermal reaction. While maintaining the structure of the precursor BiOCl, a reasonable proportion of sulfur source is added, and the molar ratio of thioacetamide to BiOCl nanosheets is controlled to be 0.04-0.06:1. Under high temperature and high pressure conditions, S 2- Ions and Bi 3+ The binding ability is strong, and uniformly doping S in the bulk structure reduces the band gap of BiOCl, greatly improving the light absorption capacity and reaching near-infrared light response.

[0021] 2. In the secondary hydrothermal reaction, as the input of sulfur source increases, the light absorption capacity of the material gradually increases. When less sulfur source is input, the light absorption capacity of the material is limited. When more sulfur source is input, although the light absorption capacity of the material is further improved, the BiOCl nanosheets will stack to make the size larger, or even corrode, and generate Bi2S3 nanosheets to cover the active sites. Therefore, the present invention inputs a reasonable proportion of sulfur source to improve the light absorption capacity of the material while maintaining the uniform morphology of the BiOCl nanosheets.

[0022] 3. In the secondary hydrothermal reaction of the present invention, due to the uniform dispersion of S and the short hydrothermal reaction time, rod-shaped Bi2S3 is not generated, the morphology of the precursor ultra-thin nanosheet BiOCl is maintained and the average size (70-120nm) is reduced, the photogenerated electron-hole separation efficiency is improved, the transfer and separation of interfacial charges are enhanced, and the photocatalytic activity of the composite material is improved. The light absorption capacity of the catalyst of the present invention is not only greatly improved in the visible light region of 380-780nm, but also has a good light response in the near-infrared light region of 780-1200nm.

[0023] 4. Compared with BiOCl nanosheets, the degradation rate of ENR by BiOCl nanosheets was 16.31% after 100 minutes of irradiation under visible light, while the degradation rate of ENR by the catalyst of the present invention was 66.87%, which greatly improved the degradation efficiency of ENR under visible light. After 100 minutes of irradiation under near-infrared light, the degradation rate of ENR by BiOCl nanosheets was almost zero, while the degradation rate of ENR by the catalyst of the present invention was 9.25%, achieving degradation performance from zero to full under near-infrared light.

[0024] 5. The present invention adopts a secondary hydrothermal method for preparation, which is simple to operate, with mild and easy-to-control conditions. A small amount of raw materials are required during the preparation process, and there is no need for complex and cumbersome operations such as centrifugation. The preparation cost is low and it is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD patterns of S-BiOCl 0.05 prepared in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4, respectively.

[0026] Figure 2 SEM images of S-BiOCl 0.05 prepared in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4, respectively.

[0027] Figure 3This is the EDS graph of S-BiOCl 0.05 prepared in Example 1.

[0028] Figure 4 The UV-visible absorption graphs of S-BiOCl 0.05 prepared in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4, respectively.

[0029] Figure 5 The ultraviolet, visible and near-infrared light absorption graphs of S-BiOCl 0.05 prepared in Example 1 and BiOCl prepared in Comparative Example 1.

[0030] Figure 6 1 is a graph showing the relationship between the residual ENR concentration and time in the photocatalytic degradation of ENR experiments using S-BiOCl 0.05 in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 in Comparative Examples 1-4.

[0031] Figure 7 This is a graph showing the relationship between the residual ENR concentration and time in the experiment of photocatalytic degradation of ENR under infrared light using S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1.

[0032] Figure 8 The impedance diagrams of S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1 are shown.

[0033] Fig. 9 The photocurrent diagrams are of S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below by way of examples. These examples are only used to illustrate the present invention and do not limit the protection scope of the present invention.

[0035] Example 1

[0036] Preparation of near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalysts:

[0037] (1) Preparation of BiOCl nanosheets: 0.4850 g of bismuth nitrate pentahydrate, 0.2275 g of mannitol and 0.2 g of polyvinylpyrrolidone K30 were placed in a beaker, and 20 mL of deionized water was added. The mixture was stirred continuously at room temperature until a transparent liquid was obtained. Then, 1 mL of saturated NaCl solution was added dropwise, and the stirring was continued for 10 min to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160°C for 180 min. After the reaction was completed, the mixture was naturally cooled. The sample was washed with anhydrous ethanol and deionized water for 3 times respectively, and freeze-dried to obtain BiOCl nanosheets.

[0038] (2) Preparation of sulfur-doped BiOCl nanosheets: 0.1300 g BiOCl (0.5 mmol) nanosheets were placed in a beaker, 10 mL deionized water was added, and the mixture was stirred continuously at room temperature until a white BiOCl suspension was obtained; 1.88 mg (0.025 mmol) thioacetamide was placed in another beaker, 10 mL deionized water was added, and the mixture was stirred continuously at room temperature until a transparent and clear thioacetamide solution was obtained; the thioacetamide solution was added to the BiOCl suspension, and the mixture was stirred to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160°C for 360 min. After the reaction was completed, the mixture was cooled naturally, and the sample was washed with anhydrous ethanol and deionized water three times each, and freeze-dried to obtain an ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.05) that responded to near-infrared light.

[0039] Example 2

[0040] Preparation of near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalysts:

[0041] (1) Preparation of BiOCl nanosheets: 0.4850 g of bismuth nitrate pentahydrate, 0.2510 g of mannitol and 0.22 g of polyvinyl pyrrolidone K30 were placed in a beaker, and 20 mL of deionized water was added. The mixture was stirred continuously at room temperature until a transparent liquid was obtained. Then, 1 mL of saturated NaCl solution was added dropwise, and the mixture was stirred for 10 min to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 150°C for 160 min. After the reaction was completed, the mixture was naturally cooled. The sample was washed with anhydrous ethanol and deionized water for 3 times respectively, and freeze-dried to obtain BiOCl nanosheets.

[0042] (2) Preparation of sulfur-doped BiOCl nanosheets: 0.1300 g BiOCl nanosheets were placed in a beaker, 10 mL deionized water was added, and the mixture was stirred continuously at room temperature until a white BiOCl suspension was obtained; 1.503 mg (0.02 mmol) thioacetamide was placed in another beaker, 10 mL deionized water was added, and the mixture was stirred continuously at room temperature until a transparent and clear thioacetamide solution was obtained; the thioacetamide solution was added to the BiOCl suspension, and the mixture was stirred to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 150 ° C for 320 min. After the reaction was completed, the mixture was cooled naturally. The sample was washed with anhydrous ethanol and deionized water for 3 times each, and freeze-dried to obtain an ultrathin nanosheet sulfur-doped BiOCl photocatalyst that responded to near-infrared light.

[0043] Example 3

[0044] Preparation of near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalysts:

[0045] (1) Preparation of BiOCl nanosheets: 0.4850 g of bismuth nitrate pentahydrate, 0.2450 g of mannitol and 0.18 g of polyvinylpyrrolidone K30 were placed in a beaker, and 20 mL of deionized water was added. The mixture was stirred continuously at room temperature until a transparent liquid was obtained. Then, 1 mL of saturated NaCl solution was added dropwise, and the stirring was continued for 10 min to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160°C for 150 min. After the reaction was completed, the mixture was naturally cooled. The sample was washed with anhydrous ethanol and deionized water for 3 times respectively, and freeze-dried to obtain BiOCl nanosheets.

[0046] (2) Preparation of sulfur-doped BiOCl nanosheets: 0.1300 g of BiOCl nanosheets were placed in a beaker, 10 mL of deionized water was added, and the mixture was stirred continuously at room temperature until a white BiOCl suspension was obtained; 2.254 mg (0.03 mmol) of thioacetamide was placed in another beaker, 10 mL of deionized water was added, and the mixture was stirred continuously at room temperature until a transparent and clear thioacetamide solution was obtained; the thioacetamide solution was added to the BiOCl suspension, and the mixture was stirred to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160°C for 300 min. After the reaction was completed, the mixture was cooled naturally, and the sample was washed with anhydrous ethanol and deionized water three times each, and freeze-dried to obtain an ultrathin nanosheet sulfur-doped BiOCl photocatalyst that responded to near-infrared light.

[0047] Comparative Example 1

[0048] Comparative Example 1 is to prepare BiOCl nanosheets according to the preparation method of BiOCl nanosheets in Example 1.

[0049] Comparative Example 2

[0050] The difference between Comparative Example 2 and Example 1 is that the amount of thioacetamide used in Comparative Example 2 is 0.94 mg (0.0125 mmol), and the rest of the preparation process and conditions are the same as those in Example 1, and a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.025) is obtained.

[0051] Comparative Example 3

[0052] The difference between Comparative Example 3 and Example 1 is that the amount of thioacetamide used in Comparative Example 3 is 2.82 mg (0.0375 mmol), and the rest of the preparation process and conditions are the same as those in Example 1, and a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.075) is obtained.

[0053] Comparative Example 4

[0054] The difference between Comparative Example 4 and Example 1 is that the amount of thioacetamide used in Comparative Example 4 is 3.74 mg (0.05 mmol), and the rest of the preparation process and conditions are the same as those in Example 1, and a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.1) is obtained.

[0055] (I) X-ray diffraction (XRD) analysis

[0056] The S-BiOCl 0.05 prepared in Example 1 and the BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4 were characterized and analyzed by X-ray diffractometer (XRD). The characterization results are as follows: Figure 1 As shown. Figure 1 It can be obtained that the peaks at 2θ=12.0°, 25.9°, 32.5°, 33.5°, 40.9°, 46.7°, 49.8°, 54.1° and 58.6° can be indexed to (001), (101), (110), (102), (112), (200), (113), (211), and (212) planes, which are the orthorhombic crystal system (JCPDS 06-0249) of BiOCl, respectively. The characteristic peaks of the sample prepared in Comparative Example 1 are consistent with the BiOCl standard card, so the sample obtained in Comparative Example 1 is determined to be a BiOCl material. The characteristic peaks of the samples prepared in Example 1 and Comparative Examples 2-4 are still consistent with the BiOCl standard card, indicating that the doping of a small amount of S has no effect on the XRD of the precursor and still maintains the crystal structure of BiOCl.

[0057] (ii) Scanning electron microscopy (SEM) analysis

[0058] The S-BiOCl 0.05 prepared in Example 1 and the BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4 were characterized and analyzed using a scanning electron microscope (SEM). The characterization results are as follows: Figure 2 shown. Figure 2 (ae) SEM images of BiOCl, S-BiOCl 0.025, S-BiOCl 0.05, S-BiOCl 0.075, and S-BiOCl 0.1, respectively. Figure 2 (a) It can be seen that the BiOCl material obtained in Comparative Example 1 is an ultra-thin nanosheet with uniform morphology and an average size of 100-130 nm. Figure 2 (b) It can be seen that the S-BiOCl 0.025 obtained in Comparative Example 2 is an ultra-thin nanosheet with uniform morphology and an average size of 80-120 nm, which is smaller than that of BiOCl. Figure 2 (c) It can be seen that the S-BiOCl 0.05 obtained in Example 1 is an ultra-thin nanosheet with uniform morphology and an average size of 70-120 nm, and the size tends to be further reduced. Figure 2 (d) It can be seen that the S-BiOCl 0.075 obtained in Comparative Example 3 is still an ultra-thin nanosheet, but its size has expanded to 90-150nm. Figure 2 (e) It can be seen that the nanosheets of the S-BiOCl 0.1 material obtained in Comparative Example 4 are corroded, many nanosheets are destroyed and stacked together, and Bi2S3 nanorods are generated. In general, as the amount of sulfur source added changes, the material size first shrinks and then increases until it is corroded by excessive sulfur source.

[0059] (III) Energy dispersive X-ray spectroscopy (EDS) analysis

[0060] Energy dispersive X-ray spectroscopy was used to characterize the S-BiOCl 0.05 prepared in Example 1. The characterization results are as follows: Figure 3 As shown. Figure 3 It can be seen that the S-BiOCl 0.05 sample obtained in Example 1 has S signals, which proves the introduction of S and the uniform distribution of S.

[0061] (IV) DRS analysis of light absorption

[0062] The ultraviolet-visible light absorption capacity of S-BiOCl 0.05 prepared in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 prepared in Comparative Examples 1-4 were analyzed. The results are as follows: Figure 4 As shown. Figure 4 It can be seen that the light absorption capacity gradually increases with the amount of sulfur input. The absorption edges of S-BiOCl 0.025 and S-BiOCl 0.05 are significantly red-shifted compared to BiOCl, while the absorption edges of S-BiOCl 0.075 and S-BiOCl 0.1 are not obvious due to the excessive improvement of light absorption capacity. In general, in the visible light region of 380-780nm, the light absorption capacity of S-BiOCl is greatly improved compared to BiCOl.

[0063] The ultraviolet, visible and near-infrared light absorption capabilities of S-BiOCl 0.05 prepared in Example 1 and BiOCl prepared in Comparative Example 1 were analyzed. The results are as follows: Figure 5 As shown. Figure 5 It can be seen that the absorption edge of S-BiOCl 0.05 prepared in Example 1 is significantly red-shifted compared with BiOCl, and its light absorption capacity is not only greatly improved in the visible light region of 380-780nm, but also has a good light response in the near-infrared light region of 780-1200nm.

[0064] Application Example 1

[0065] 20 mg of the S-BiOCl 0.05 catalyst of Example 1 was dispersed into 50 mL of 0.4×10 -4 mol / L enrofloxacin (ENR) solution. A 500W Xe lamp equipped with a 420nm cutoff filter was used to simulate visible light. Before illumination, the mixed solution was stirred magnetically in the dark for 30 minutes to reach the adsorption-desorption equilibrium between the photocatalyst and the pollutant. After turning on the light, the reactor was irradiated under simulated sunlight, the distance between the reactor and the lamp was kept at 6cm, and about 4mL of the suspension was taken out every 20min. After centrifugation to remove the catalyst, the absorbance of the supernatant was measured by a UV-visible spectrophotometer. The absorbance intensity of ENR at a wavelength of 272nm was recorded. It was calculated that the degradation rate of ENR by S-BiOCl 0.05 was 66.87% after 100min of illumination under visible light.

[0066] Application Comparative Example 1

[0067] The difference between Application Comparative Example 1 and Application Example 1 is that the catalyst used in Application Comparative Example 1 is BiOCl in Application Example 1, and the other reaction conditions are the same as those in Application Example 1. In this reaction, the degradation rate of BiOCl to ENR is 16.31% after irradiation under visible light for 100 minutes.

[0068] Application Comparative Example 2

[0069] The difference between Application Comparative Example 2 and Application Example 1 is that the catalyst used in Application Comparative Example 2 is S-BiOCl 0.025 in Comparative Example 2, and the other reaction conditions are the same as those in Application Example 1. In the reaction, the degradation rate of S-BiOCl 0.025 to ENR is 46.87% after irradiation under visible light for 100 minutes.

[0070] Application Comparative Example 3

[0071] The difference between Application Comparative Example 3 and Application Example 1 is that the catalyst used in Application Comparative Example 3 is S-BiOCl 0.075 in Comparative Example 3, and the other reaction conditions are the same as those in Application Example 1. In the reaction, the degradation rate of S-BiOCl 0.075 to ENR is 43.77% after irradiation under visible light for 100 minutes.

[0072] Application Comparative Example 4

[0073] The difference between Application Example 4 and Application Example 1 is that the catalyst used in Application Example 3 is S-BiOCl 0.1 in Application Example 4, and the other reaction conditions are the same as those in Application Example 1. In the reaction, the degradation rate of S-BiOCl 0.1 to ENR is 15.06% after irradiation under visible light for 100 minutes.

[0074] Analysis of material catalytic performance

[0075] The effects of the catalysts in Example 1 and Comparative Examples 1-4 on photocatalytic degradation of ENR were analyzed. The results are as follows: Figure 6-9 shown. Figure 6 The relationship between the residual ENR concentration and time in the photocatalytic degradation of ENR by using S-BiOCl 0.05 in Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 in Comparative Examples 1-4 is shown. Figure 6 It can be seen that in the presence of photocatalyst, as the illumination time increases, the residual ENR concentration in the solution gradually decreases. After 100 minutes of illumination, the degradation rate of BiOCl is only 16.31%; S-BiOCl 0.025 and S-BiOCl 0.075 are 46.87% and 43.77% respectively; the degradation effect of S-BiOCl 0.1 is not ideal, at 15.06%, and the generation of Bi2S3 and the destruction of the ultra-thin nanosheet morphology lead to a decrease in photocatalytic activity; S-BiOCl 0.05 is 66.87%, which is the best effect, about 4.1 times that of the BiOCl precursor.

[0076] In order to analyze the effect of the catalysts in Application Example 1 and Application Comparative Example 1 on photocatalytic degradation of ENR under near-infrared light, a 50W 850nm LED near-infrared lamp was used as a light source. Figure 7 The relationship between the residual ENR concentration and time in the photocatalytic degradation of ENR by S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1 under infrared light is shown. Figure 7 It can be seen that in the presence of photocatalyst, as the illumination time increases, the residual ENR concentration in the solution gradually decreases. After 100 minutes of illumination, the degradation rate of BiOCl is almost zero, and no reaction occurs; the degradation rate of S-BiOCl 0.05 is 9.25%, achieving a degradation effect from zero to full.

[0077] Figure 8 The impedance diagrams of S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1 show that S-BiOCl 0.05 shows a smaller arc in the two samples. Since a smaller arc radius means a lower interface resistance, S-BiOCl 0.05 has a higher interface charge transfer efficiency.

[0078] Fig. 9 The photocurrent graph of S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1, where the photocurrent density of BiOCl is about 0.02 μA / cm 2 , the photocurrent density of S-BiOCl 0.05 is about 0.18μA / cm 2 , which is 9 times that of BiOCl. BiOCl 0.05 exhibits better photocurrent response and higher photogenerated electron-hole separation efficiency.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. 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 a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, characterized in that: The following steps are involved: (1) Preparation of BiOCl nanosheets: bismuth nitrate pentahydrate, mannitol and polyvinyl pyrrolidone were added to water and stirred continuously at room temperature, and then a saturated sodium chloride solution was added. After stirring, the resulting mixed solution was placed in a hydrothermal reactor for a hydrothermal reaction. After the reaction was completed, the mixture was naturally cooled, and the resulting product was washed and freeze-dried to obtain BiOCl nanosheets; (2) Preparation of sulfur-doped BiOCl nanosheets: placing the BiOCl nanosheets prepared in step (1) in water and stirring to obtain a BiOCl dispersion; placing thioacetamide in water and stirring to obtain a thioacetamide solution; The thioacetamide solution is added to the BiOCl dispersion and stirred to obtain a mixed solution. The mixed solution is placed in a hydrothermal reactor for a secondary hydrothermal reaction. After the reaction is completed, the mixed solution is naturally cooled. The obtained product is washed and freeze-dried to obtain an ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light.

2. The method for preparing the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 1, characterized in that: In step (2), the molar ratio of thioacetamide to BiOCl nanosheets is 0.04-0.06:1, and the mass ratio is 1.5-2.3:

130.

3. The method for preparing the near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 1, characterized in that: In step (2), the temperature of the hydrothermal reaction is 150-160° C. and the time is 5-6 hours.

4. The method for preparing the near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 1, characterized in that: In step (1), the mass ratio of the bismuth nitrate pentahydrate, mannitol and polyvinyl pyrrolidone is 1:0.4-0.6:0.3-0.

5.

5. The method for preparing the near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 1, characterized in that: In step (1), the mass ratio of the bismuth nitrate pentahydrate to the saturated sodium chloride solution is 1 g: 1.5-3 mL.

6. The method for preparing the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 1, characterized in that: In step (1), the temperature of the hydrothermal reaction is 150-160° C. and the time is 2.5-3 h.

7. A near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst prepared by the preparation method as described in any one of claims 1 to 6.

8. The near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 7, characterized in that: The structure of the near-infrared light-responsive ultra-thin nanosheet sulfur-doped BiOCl photocatalyst is an ultra-thin nanosheet with uniform morphology, an average size of 70 to 120 nm, and a light response in the near-infrared light region of 780 to 1200 nm.

9. Use of the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst as claimed in claim 7 in photocatalytic degradation of enrofloxacin.

10. The use of the near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 9, characterized in that: The degradation rate of the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst for enrofloxacin is 66.5-67.0% after irradiation under visible light for 100 minutes, and the degradation rate of the enrofloxacin is 9.2-9.3% after irradiation under near-infrared light for 100 minutes.

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