A near-infrared responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, its preparation method and application

Abstract

This invention discloses a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, its preparation method, and its application, belonging to the field of photocatalytic materials technology. The preparation method of this invention includes the following technical steps: (1) preparation of BiOCl nanosheets; (2) preparation of sulfur-doped BiOCl nanosheets. This invention employs a secondary hydrothermal method and controls the amount of thioacetamide and BiOCl nanosheets to obtain a catalyst with uniform morphology, ultrathin nanosheets, with an average size of 70–120 nm. It exhibits light response in the near-infrared region of 780–1200 nm, demonstrating good light absorption and near-infrared light response. When applied to the catalytic degradation of ENR, the catalyst showed a degradation rate of 66.87% under visible light, indicating good degradation performance; and a degradation rate of 9.25% under near-infrared light, achieving degradation performance from zero to existing levels. The preparation method of this invention is simple, with mild and easily controllable conditions, low raw material consumption, and no need for complex operations such as centrifugation. It has low preparation costs and is easy to promote and apply.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, its preparation method, and its application. Background Technology

[0002] Enrofloxacin (ENR) is a common fluoroquinolone antibiotic widely used in human and veterinary medicine. However, because ENR is only partially metabolized in humans and animals and has poor biodegradability, most ENR is ultimately released into the aquatic environment. Even trace amounts of ENR in water can harm human health and aquatic ecosystems. Therefore, removing ENR from the aquatic environment has become increasingly urgent, necessitating the development of an economical, efficient, and environmentally friendly ENR treatment technology.

[0003] Photocatalysis is considered a promising and sustainable technology for pollutant removal. It can degrade or even mineralize pollutants into harmless CO2 and H2O under solar excitation, providing a new pathway for the treatment of antibiotic-like pollutants. However, most photocatalysts have narrow light response ranges and cannot effectively absorb infrared light (near-infrared light accounts for about 50% of total solar energy), severely limiting the utilization of sunlight and resulting in low quantum efficiency. Furthermore, the photocatalytic activity of most photocatalysts is far from satisfactory, mainly due to the high recombination rate of photoinduced charge carriers in semiconductor charge transport, i.e., redox reactions on the surface. Therefore, developing novel photocatalytic materials with broad spectral responses is of great significance. In recent years, elemental doping has been widely used to improve the photocatalytic performance of BiOCl. BiOCl only has good absorption in the ultraviolet region; the tunable introduction of nonmetallic sulfur doping can generate local energy levels, reducing the band gap of semiconductor materials to enhance visible light absorption and even achieve near-infrared light response. Patent publication number CN 107999095 A discloses a method for preparing sulfur-doped bismuth oxychloride powder photocatalytic material. The BiOCl precursor prepared by this method has a large size and non-uniform morphology. In the subsequent sulfur doping process, BiOCl is dissolved in hydrochloric acid solution, an additional chlorine source is introduced, and then a sulfur source is introduced, which is equivalent to a dissolution and reprecipitation process. In this process, the doping of S is not uniform (the size and morphology of electron microscopy are not uniform), the improvement of light absorption capacity (as shown by light absorption spectrum) is not obvious, and although the size of the nanosheets is reduced, they are still large and have non-uniform morphology.

[0004] Based on the above, this invention proposes a method for preparing near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst. A secondary hydrothermal method is used to uniformly dope BiOCl nanosheets with S under high temperature and pressure, maintaining the morphology of the ultrathin BiOCl nanosheet precursor while reducing the average size. This significantly enhances the catalyst's light absorption capacity, improves the efficiency of photogenerated electron-hole separation, and strengthens the transfer and separation of interfacial charges, enabling the degradation of ENR from zero to positive under near-infrared light response. Summary of the Invention

[0005] To address the above problems, this invention provides a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst, its preparation method, and its application. By employing a secondary hydrothermal method and controlling the amount of thioacetamide and BiOCl nanosheets, the prepared catalyst is an ultrathin nanosheet with uniform morphology, exhibiting good light absorption capacity and achieving near-infrared light response.

[0006] This invention is achieved through the following technical solution:

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

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

[0009] (2) Preparation of sulfur-doped BiOCl nanosheets: The BiOCl nanosheets from step (1) were placed in water and stirred to obtain a BiOCl dispersion; thioacetamide was placed in water and stirred to obtain a thioacetamide solution; the thioacetamide solution was added to the BiOCl dispersion and stirred to obtain a mixed solution; the mixed solution was placed in a hydrothermal reactor for a second hydrothermal reaction, and after the reaction was completed, it was naturally cooled. The obtained product was washed and freeze-dried to obtain a near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst.

[0010] Further, in step (2), the molar ratio of the thioacetamide to the BiOCl nanosheets is 0.04 to 0.06:1, and the mass ratio is 1.5 to 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] Further, in step (1), the mass ratio of bismuth nitrate pentahydrate, mannitol and polyvinylpyrrolidone is 1:0.4-0.6:0.3-0.5.

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

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

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

[0016] Furthermore, the near-infrared responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst has a structure of uniformly morphological ultrathin nanosheets with an average size of 70–120 nm, and exhibits photoresponse in the near-infrared region of 780–1200 nm.

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

[0018] Furthermore, the near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst exhibits a degradation rate of 66.5–67.0% for enrofloxacin after 100 min of visible light irradiation and a degradation rate of 9.2–9.3% for enrofloxacin after 100 min of near-infrared light irradiation.

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

[0020] 1. This invention synthesizes BiOCl nanosheets in a primary hydrothermal reaction, and then performs sulfur doping on the BiOCl nanosheets in a secondary hydrothermal reaction. While maintaining the structure of the BiOCl precursor, a suitable proportion of sulfur source is added, and the molar ratio of thioacetamide to BiOCl nanosheets is controlled at 0.04–0.06:1. Under high temperature and high pressure conditions, S… 2- Ions and Bi 3+ With strong binding ability, uniform doping of S in the bulk structure reduces the band gap of BiOCl, greatly improving the light absorption capacity and achieving near-infrared light response.

[0021] 2. In the secondary hydrothermal reaction, the light absorption capacity of the material gradually increases with the increase of sulfur source input. With less sulfur source input, the improvement in light absorption capacity is limited. While with more sulfur source input, although the light absorption capacity further increases, the BiOCl nanosheets stack, increasing their size and even corroding, forming Bi2S3 nanosheets that obscure the active sites. Therefore, this invention uses a reasonable proportion of sulfur source to improve the light absorption capacity of the material while maintaining the uniformity of the BiOCl nanosheet morphology.

[0022] 3. In the secondary hydrothermal reaction of this invention, due to the uniform dispersion of S and the shorter hydrothermal reaction time, rod-shaped Bi₂S₃ is not generated, maintaining the morphology of the precursor ultrathin nanosheets BiOCl and reducing the average size (70–120 nm). This improves the photogenerated electron-hole separation efficiency, enhances the transfer and separation of interfacial charges, and improves the photocatalytic activity of the composite material. The light absorption capacity of the catalyst of this invention is significantly improved not only in the visible light region of 380–780 nm, but also in the near-infrared region of 780–1200 nm.

[0023] 4. Compared to BiOCl nanosheets, after 100 min of visible light irradiation, the degradation rate of ENR by BiOCl nanosheets was 16.31%, while the degradation rate of ENR by the catalyst of this invention was 66.87%, demonstrating a significant improvement in ENR degradation efficiency under visible light. After 100 min of near-infrared light irradiation, the degradation rate of ENR by BiOCl nanosheets was almost zero, while the degradation rate of ENR by the catalyst of this invention was 9.25%, achieving a degradation performance from zero to positive under near-infrared light.

[0024] 5. This invention uses a secondary hydrothermal method for preparation, which is simple to operate, has mild and easily controllable conditions, requires a small amount of raw materials, and does not require complex and cumbersome operations such as centrifugation. The preparation cost is low and it is easy to promote and apply. Attached Figure Description

[0025] Figure 1 The XRD patterns are 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 3The image shows the EDS diagram of S-BiOCl 0.05 obtained in Example 1.

[0028] Figure 4 The UV-Vis absorption spectra 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 are shown.

[0029] Figure 5 The UV-Vis-NIR absorption spectra of S-BiOCl 0.05 prepared in Example 1 and BiOCl prepared in Comparative Example 1 are shown.

[0030] Figure 6 The graph shows the relationship between residual ENR concentration and time in the photocatalytic degradation experiments of ENR 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 The graph shows the relationship between the residual ENR concentration and time in the photocatalytic degradation experiment of ENR under infrared light using S-BiOCl 0.05 in Example 1 and BiOCl in Comparative Example 1.

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

[0033] Figure 9 The photocurrent diagrams are for S-BiOCl 0.05 in Application Example 1 and BiOCl in Comparative Example 1. Detailed Implementation

[0034] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection 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: 0.4850g of bismuth nitrate pentahydrate, 0.2275g of mannitol and 0.2g of polyvinylpyrrolidone K30 were placed in a beaker, 20mL of deionized water was added, and the mixture was stirred continuously at room temperature until a clear liquid was obtained. Then, 1mL of saturated NaCl solution was added dropwise, and the mixture was stirred for another 10min to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160℃ for 180min. After the reaction was completed, the mixture was naturally cooled. The sample was washed three times each with anhydrous ethanol and deionized water, and then freeze-dried to obtain BiOCl nanosheets.

[0038] (2) Preparation of sulfur-doped BiOCl nanosheets: 0.1300 g of BiOCl (0.5 mmol) nanosheets were placed in a beaker, and 10 mL of deionized water was added. The mixture was stirred continuously at room temperature until a white BiOCl suspension was obtained. 1.88 mg (0.025 mmol) of thioacetamide was placed in another beaker, and 10 mL of deionized water was added. 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 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 naturally cooled. The sample was washed three times each with anhydrous ethanol and deionized water. After freeze-drying, a near-infrared responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.05) was obtained.

[0039] Example 2

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

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

[0042] (2) Preparation of sulfur-doped BiOCl nanosheets: 0.1300 g of BiOCl nanosheets were placed in a beaker, and 10 mL of deionized water was added. The mixture was stirred continuously at room temperature until a white BiOCl suspension was obtained. 1.503 mg (0.02 mmol) of thioacetamide was placed in another beaker, and 10 mL of deionized water was added. 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 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 allowed to cool naturally. The sample was washed three times each with anhydrous ethanol and deionized water. After freeze-drying, near-infrared responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst was obtained.

[0043] Example 3

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

[0045] (1) Preparation of BiOCl nanosheets: 0.4850g of bismuth nitrate pentahydrate, 0.2450g of mannitol and 0.18g of polyvinylpyrrolidone K30 were placed in a beaker, 20mL of deionized water was added, and the mixture was stirred continuously at room temperature until a clear liquid was obtained. Then, 1mL of saturated NaCl solution was added dropwise, and the mixture was stirred for another 10min to obtain a mixed solution. The mixed solution was placed in a hydrothermal reactor and reacted at 160℃ for 150min. After the reaction was completed, the mixture was naturally cooled. The sample was washed three times each with anhydrous ethanol and deionized water, and then 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, and 10 mL of deionized water was added. 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, and 10 mL of deionized water was added. 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 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 allowed to cool naturally. The sample was washed three times each with anhydrous ethanol and deionized water. After freeze-drying, near-infrared responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst was obtained.

[0047] Comparative Example 1

[0048] Comparative Example 1 shows BiOCl nanosheets prepared 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), while the rest of the preparation process and conditions are the same as those in Example 1, resulting in near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.025).

[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), while the rest of the preparation process and conditions are the same as those in Example 1, resulting in near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.075).

[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), while the rest of the preparation process and conditions are the same as those in Example 1, resulting in near-infrared light-responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst (denoted as S-BiOCl 0.1).

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

[0056] X-ray diffraction (XRD) was used to characterize and analyze 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. The characterization results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the peaks located 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 the planes (001), (101), (110), (102), (112), (200), (113), (211), and (212), which are the orthorhombic crystal system of BiOCl (JCPDS 06-0249). The characteristic peaks of the sample prepared in Comparative Example 1 are consistent with the BiOCl standard card, thus confirming that the sample obtained in Comparative Example 1 is 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 small amount of S doping 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 scanning electron microscopy (SEM). The characterization results are as follows: Figure 2 As shown. Figure 2 (ae) are SEM images of BiOCl, S-BiOCl 0.025, S-BiOCl 0.05, S-BiOCl 0.075, and S-BiOCl 0.1, respectively. From... Figure 2 (a) It can be seen that the BiOCl material obtained in Comparative Example 1 is an ultrathin nanosheet with a uniform morphology and an average size of 100-130 nm. From Figure 2 (b) It can be seen that the S-BiOCl 0.025 obtained in Comparative Example 2 is an ultrathin nanosheet with a 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 ultrathin nanosheet with a uniform morphology and an average size of 70-120 nm, showing a trend of further size reduction. However, from Figure 2 (d) It can be seen that although the S-BiOCl 0.075 obtained in Comparative Example 3 is still an ultrathin nanosheet, its size has increased to 90-150 nm. From Figure 2 (e) It can be seen that the nanosheets of the S-BiOCl 0.1 material obtained in Comparative Example 4 are corroded, with many nanosheets being destroyed and stacked together, accompanied by the formation of Bi2S3 nanorods. In general, with the change of sulfur source doping amount, 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] The S-BiOCl 0.05 prepared in Example 1 was characterized and analyzed by energy-dispersive X-ray spectroscopy. The characterization results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the S-BiOCl 0.05 sample obtained in Example 1 showed the presence of S signal, proving the introduction of S and that S was evenly distributed.

[0061] (iv) Light Absorption DRS Analysis

[0062] The UV-Vis 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, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the light absorption capacity gradually increases with the amount of sulfur added. The absorption edges of S-BiOCl 0.025 and S-BiOCl 0.05 show a significant red shift compared to BiOCl, while the absorption edges of S-BiOCl 0.075 and S-BiOCl 0.1 are not significant due to the excessively strong increase in light absorption capacity. In general, in the visible light region of 380-780 nm, the light absorption capacity of S-BiOCl is significantly improved compared to BiCOl.

[0063] The UV-Vis-NIR light absorption capacity of S-BiOCl 0.05 prepared in Example 1 and BiOCl prepared in Comparative Example 1 were analyzed, and the results are as follows: Figure 5 As shown. From Figure 5 It can be seen that the absorption edge of S-BiOCl 0.05 prepared in Example 1 has a significant red shift compared to BiOCl, and its light absorption capability 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 from Example 1 was dispersed into 50 mL of a 0.4 × 10⁻⁵ mL photoreactor. -4 The photocatalyst was dissolved in a mol / L enrofloxacin (ENR) solution. Visible light was simulated using a 500W Xe lamp equipped with a 420nm cutoff filter. Before illumination, the mixture was magnetically stirred in the dark for 30 min to achieve adsorption-desorption equilibrium between the photocatalyst and the contaminant. After the lamp was turned on, the reactor was irradiated under simulated sunlight, maintaining a distance of 6 cm between the reactor and the lamp. Approximately 4 mL of suspension was collected every 20 min. After centrifugation to remove the catalyst, the absorbance of the supernatant was measured using a UV-Vis spectrophotometer. The absorbance intensity of ENR at 272 nm was recorded. Calculations showed that after 100 min of visible light illumination, the degradation rate of ENR by S-BiOCl 0.05 was 66.87%.

[0066] Application Comparative Example 1

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

[0068] Application Comparative Example 2

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

[0070] Application Comparative Example 3

[0071] The difference between Comparative Example 3 and Application Example 1 is that the catalyst used in Comparative Example 3 is S-BiOCl 0.075, which was also used in Comparative Example 3. All other reaction conditions are the same as in Application Example 1. In this reaction, after 100 min of visible light irradiation, the degradation rate of ENR by S-BiOCl 0.075 was 43.77%.

[0072] Application Comparative Example 4

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

[0074] Catalytic performance analysis of materials

[0075] The photocatalytic degradation effect of the catalysts in Application Example 1 and Comparative Examples 1-4 on ENR was analyzed, and the results are as follows: Figure 6-9 As shown. Figure 6 This shows the relationship between residual ENR concentration and time in the photocatalytic degradation experiments of ENR using S-BiOCl 0.05 in Application Example 1 and BiOCl, S-BiOCl 0.025, S-BiOCl 0.075, and S-BiOCl 0.1 in Comparative Examples 1-4. (The text is incomplete and ends abruptly.) Figure 6 It can be seen that in the presence of the photocatalyst, the concentration of residual ENR in the solution gradually decreases with the extension of irradiation time. After 100 min of irradiation, the degradation rate of BiOCl was only 16.31%; S-BiOCl 0.025 and S-BiOCl 0.075 were 46.87% and 43.77%, respectively; the degradation effect of S-BiOCl 0.1 was not ideal, at 15.06%, with the formation of Bi2S3 and the destruction of the morphology of ultrathin nanosheets leading to a decrease in photocatalytic activity; S-BiOCl 0.05 had the best effect at 66.87%, about 4.1 times that of the BiOCl precursor.

[0076] 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 the light source. Figure 7 This shows the relationship between the residual ENR concentration and time in the photocatalytic degradation experiment of S-BiOCl 0.05 in Application Example 1 and BiOCl in Comparative Example 1 under infrared light. Figure 7 It can be seen that in the presence of a photocatalyst, the concentration of residual ENR in the solution gradually decreases with the extension of light irradiation time. After 100 min of light irradiation, 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 some.

[0077] Figure 8 For the impedance diagrams of S-BiOCl 0.05 in Application Example 1 and BiOCl in Comparative Example 1, S-BiOCl 0.05 showed a smaller arc in both samples. Since a smaller arc radius implies a lower interface resistance, S-BiOCl 0.05 exhibits higher interface charge transfer efficiency.

[0078] Figure 9 The photocurrent plots are shown for S-BiOCl 0.05 in Application Example 1 and BiOCl in Comparative Example 1, where the photocurrent density of BiOCl is approximately 0.02 μA / cm. 2 The photocurrent density of S-BiOCl 0.05 is approximately 0.18 μA / cm². 2 It 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 principles of the present invention should be included within 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 method comprises the following steps: (1) BiOCl nanosheet preparation: take bismuth nitrate pentahydrate, mannitol and polyvinylpyrrolidone and add them into water, continuously stir at room temperature, then add a saturated sodium chloride solution, stir, then place the obtained mixed solution in a hydrothermal reaction kettle for a first hydrothermal reaction, naturally cool after the reaction is completed, wash the obtained product, and freeze-dry to obtain ultra-thin BiOCl nanosheets; The mass ratio of the bismuth nitrate pentahydrate, mannitol and polyvinylpyrrolidone is 1:0.4-0.6:0.3-0.5; (2) Sulfur-doped BiOCl nanosheet preparation: place the ultra-thin BiOCl nanosheets in step (1) in water, stir, and obtain a BiOCl dispersion; take thioacetamide and place it in water, stir, and obtain a thioacetamide solution; Add the thioacetamide solution to the BiOCl dispersion, stir, and obtain a mixed solution; place the mixed solution in a hydrothermal reaction kettle for a second hydrothermal reaction, naturally cool after the reaction is completed, wash the obtained product, and freeze-dry to obtain an ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light; The temperature of the hydrothermal reaction is 150-160°C, and the time is 5-6 h; The molar ratio of the thioacetamide to the ultra-thin BiOCl nanosheets is 0.04-0.06:

1.

2. The method for preparing 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.

3. The method for preparing 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.

4. An ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light, which is prepared by the method in any one of claims 1-3. 5.The near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 4, characterized in that, The structure of the ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light is a uniform ultra-thin nanosheet with an average size of 70-120 nm and a light response in the near-infrared light region of 780-1200 nm.

6. Application of the ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light in claim 4 in photocatalytic degradation of enrofloxacin.

7. Use of the near-infrared light responsive ultrathin nanosheet sulfur-doped BiOCl photocatalyst according to claim 6, characterized in that, The degradation rate of the ultra-thin nanosheet sulfur-doped BiOCl photocatalyst that responds to near-infrared light on enrofloxacin is 66.5-67.0% after 100 min of visible light irradiation and 9.2-9.3% after 100 min of near-infrared light irradiation.

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