A sunflower-shaped Bi 24 O 31 Cl 10 Photocatalysts, their preparation methods and applications

Abstract

The application belongs to the technical field of material preparation and visible light photocatalysis, and particularly relates to a sunflower-like Bi 24 O 31 Cl 10 photocatalyst and a preparation method and application thereof. The photocatalyst is synthesized by using BiCl3 and NaOH as raw materials through a two-step solvothermal method, and the catalyst is formed by self-assembly of Bi 24 O 31 Cl 10 nanosheets, and has a unique morphology. The application has low preparation condition requirement, simple operation, cheap and easily available raw materials, and is environment-friendly. The prepared catalyst can effectively prevent the stacking and agglomeration of Bi 24 O 31 Cl 10 nanosheets, has a large specific surface area, rich reaction active sites, a suitable band gap, good light absorption, high photo-generated carrier separation efficiency and other advantages, and has excellent photocatalytic performance. The application can be applied to the treatment of wastewater containing organic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of material preparation and visible light photocatalysis technology, specifically relating to a sunflower-shaped Bi 24 O 31 Cl 10 Photocatalysts, their preparation methods, and applications. Background Technology

[0002] With the large-scale industrial application of various aromatic organic compounds, environmental problems such as water pollution are becoming increasingly serious. Once released into the environment, these aromatic organic compounds pollute drinking water, directly threatening scarce available water resources. Therefore, to meet the needs of green, clean, and sustainable development strategies, the degradation of residual aromatic organic compounds has become an important task. Advanced oxidation processes, by generating species with strong oxidizing activity, can degrade organic pollutants in water into non-toxic products, becoming a hot topic in solving water pollution problems. Although solar photocatalytic oxidation has been widely used in water treatment, many problems still exist in practical production. For example, low quantum efficiency, narrow photocatalytic response range, and poor stability. Therefore, finding and preparing efficient and stable visible light photocatalytic materials is a prerequisite for the practical application of photocatalysis technology and one of the primary tasks that photocatalytic material researchers need to solve.

[0003] As is well known, the band structure of semiconductors is largely determined by their chemical composition, playing a crucial role in their photoresponse range and redox potential. Non-stoichiometric bismuth oxyhalides are an important class of visible-light photocatalysts, possessing a unique layered structure and excellent photophysical and chemical properties. Furthermore, these materials are non-toxic and chemically stable. These fascinating characteristics have attracted considerable research interest and have potential applications in environmental remediation. Among them, Bi... 24 O 31 Cl 10 It exhibits excellent photocatalytic pollutant degradation performance under visible light. However, Bi... 24 O 31 Cl 10 The rapid recombination of photogenerated electrons and holes remains a major barrier limiting the widespread application of Bi. Therefore, how to promote the rapid recombination of photogenerated electrons and holes is a key challenge. 24 O 31 Cl 10 Effective carrier separation is crucial for improving photocatalytic performance. The catalytic activity of a photocatalyst is inextricably linked to its morphology and structure. However, current research on Bi... 24 O 31 Cl 10 Research on photocatalysts is limited, especially regarding improving their photocatalytic performance through morphological manipulation. According to existing literature, Bi0.05 has been obtained... 24 O 31Cl 10 The morphologies mainly consist of bulk materials and two-dimensional nanosheets (ACS Appl. Nano Mater. 2022, 5, 17226-17233; Appl. Catal., B: Environ. 2015, 165, 668-675; J. Mater. Chem. A, 2018, 6, 24350-24357; ChemSusChem 2019, 12, 2740-2747; Catal. Lett. 2017, 147, 2167-2172). Bulk materials have a larger phase migration distance for photogenerated carriers, increasing the recombination probability and limiting photocatalytic efficiency. Although two-dimensional nanosheets have a smaller phase migration distance for photogenerated carriers, which is beneficial for improving photocatalytic activity, they are prone to stacking and agglomeration, leading to a significant reduction in specific surface area and the covering of numerous active sites. Compared to bulk and two-dimensional Bi... 24 O 31 Cl 10 Bi multi-level structure constructed with nanosheets as basic units 24 O 31 Cl 10 This not only effectively prevents the aggregation of nanomaterials but also significantly increases their specific surface area, adds reactive sites, alters the band gap, enhances light absorption, and promotes photogenerated carrier separation, thereby improving photocatalytic performance. In view of this, the preparation of multi-level Bi... 24 O 31 Cl 10 The research and development of novel non-stoichiometric bismuth halide photocatalysts is of great significance, but how to prepare hierarchical Bi structures with excellent structure and performance remains a challenge. 24 O 31 Cl 10 This has become a problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a sunflower-shaped Bi 24 O 31 Cl 10 Photocatalysts, their preparation methods, and applications. The sunflower-shaped Bi... 24 O 31 Cl 10 Photocatalyst with Bi 24 O 31 Cl 10 Nanosheets are used as basic units to construct multi-level structures, which can not only effectively prevent the aggregation of nanomaterials, but also significantly increase their specific surface area, increase reactive sites, change the band gap of the material, enhance light absorption, and promote the separation of photogenerated carriers, thereby improving photocatalytic performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a sunflower-shaped Bi 24 O 31 Cl 10 Photocatalyst, the Bi 24 O 31 Cl 10 The photocatalyst has a particle size of 2–5 μm; the catalyst is Bi. 24 O 31 Cl 10 A sunflower-like structure formed by the self-assembly of nanosheets. Preferably, the Bi... 24 O 31 Cl 10 The thickness of the nanosheets is 5–20 nm.

[0007] The present invention also provides the sunflower-shaped Bi 24 O 31 Cl 10 A method for preparing a photocatalyst, wherein the catalyst is prepared by solvothermal synthesis of Bi. x O y Cl z As a precursor, it is directly obtained using a solvothermal method, specifically including the following steps:

[0008] (1) NaOH aqueous solution was added dropwise to BiCl3 ethanol solution, stirred until homogeneous, and then heated to 90-140℃ for reaction. After repeated centrifugation, washing, and drying, Bi was obtained. x O y Cl z Precursor;

[0009] (2) The Bi described in step (1) x O y Cl z The precursor was ultrasonically and uniformly dispersed in ethylene glycol, transferred to a polytetrafluoroethylene reactor, and reacted at 180°C. After repeated centrifugation, washing, and drying, sunflower-shaped Bi was obtained. 24 O 31 Cl 10 Photocatalyst.

[0010] Preferably, the molar ratio of BiCl3 to NaOH in step (1) is 1:4 to 6.

[0011] Preferably, the reaction time in step (1) is 8-16 hours.

[0012] Preferably, the volume ratio of water in the NaOH aqueous solution and ethanol in the BiCl3 ethanol solution in step (1) is 1:1.

[0013] Preferably, the Bi in step (2) x O y Cl z The mass-to-volume ratio of the precursor to ethylene glycol was 20:7 mg / mL.

[0014] Preferably, the reaction time in step (2) is 0.5-2 hours.

[0015] Preferably, in both steps (1) and (2), deionized water and anhydrous ethanol are used for multiple washings; the drying in step (2) is performed by vacuum drying at 60°C for 12 hours. This invention also provides the above-mentioned sunflower-shaped Bi 24 O 31 Cl 10 The application of photocatalysts involves using the catalyst for the visible light catalytic degradation of organic pollutants in water.

[0016] Preferably, the organic pollutant is rhodamine B, bisphenol A, 2-naphthol, or tetracycline hydrochloride.

[0017] Compared with the prior art, the significant advantages of the present invention are:

[0018] The photocatalyst described in this invention differs from existing Bi photocatalysts in terms of structure, preparation method, and catalytic performance. 24 O 31 Cl 10 The catalysts are significantly different.

[0019] (1) This invention uses BiCl3 and NaOH as raw materials and employs a two-step solvothermal method to synthesize a multi-level sunflower-like BiCl3 structure. 24 O 31 Cl 10 The catalyst prepared is made of Bi 24 O 31 Cl 10 Nanosheets self-assemble to form unique morphologies.

[0020] (2) The preparation conditions of this invention are low, the operation is simple, the raw materials are cheap and readily available, and it is environmentally friendly.

[0021] (3) The catalyst prepared by the present invention can effectively prevent Bi 24 O 31 Cl 10 The stacking and aggregation of nanosheets has advantages such as large specific surface area, abundant reactive sites, suitable band gap, good light absorption, and high photogenerated carrier separation efficiency, while also exhibiting excellent photocatalytic performance.

[0022] (4) This invention can be applied to the treatment of wastewater containing organic pollutants. Attached Figure Description

[0023] Figure 1 The sunflower-shaped Bi synthesized in Example 1 of this invention 24 O 31 Cl 10 XRD pattern of photocatalyst;

[0024] Figure 2 The sunflower-shaped Bi synthesized in Example 1 of this invention 24 O 31 Cl 10 Scanning electron microscope image of the photocatalyst;

[0025] Figure 3 The sunflower-shaped Bi synthesized in Example 1 of this invention 24 O 31 Cl 10 Photocatalytic degradation effect of photocatalysts on (A) Rhodamine B, (B) Bisphenol A, (C) 2-Naphthol and (D) Tetracycline hydrochloride. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0027] Example 1

[0028] A sunflower-shaped Bi 24 O 31 Cl 10 The preparation method of the photocatalyst includes the following steps:

[0029] (1) BiCl3 and NaOH in a molar ratio of 1:5 were dissolved in 30 mL of anhydrous ethanol and deionized water, respectively. After stirring for 10 minutes, the NaOH aqueous solution was added dropwise to the BiCl3 ethanol solution, and stirring was continued for 1 hour. The mixture was then transferred to a 100 mL polytetrafluoroethylene reactor, heated to 120 °C and kept at that temperature for 12 hours. After naturally cooling to room temperature, the product was washed multiple times with deionized water and anhydrous ethanol, respectively. The precipitate was collected by centrifugation and dried to obtain BiCl3. x O y Cl z Precursor.

[0030] (2) The Bi obtained in step (1) x O y Cl z200 mg was ultrasonically dispersed in 70 mL of ethylene glycol and stirred for 1 hour. The mixture was then transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, heated to 180 °C and held for 1 hour. After naturally cooling to room temperature, the product was washed multiple times with deionized water and anhydrous ethanol, and the precipitate was collected by centrifugation and dried at 100 °C for 12 hours to obtain sunflower-shaped Bi. 24 O 31 Cl 10 Photocatalyst.

[0031] The catalyst synthesized in Example 1 was characterized by X-ray powder diffraction. The results showed that the synthesized catalyst was Bi. 24 O 31 Cl 10 See appendix Figure 1 .

[0032] The catalyst synthesized by the method in Example 1 was observed by scanning electron microscopy, and the results showed that the synthesized Bi 24 O 31 Cl 10 Bi exhibits a sunflower-like morphology with a particle size of 2–5 μm, formed by the self-assembly of nanosheets. 24 O 31 Cl 10 The nanosheets have a thickness of 5–20 nm; see appendix. Figure 2 .

[0033] 20 mg of the catalyst synthesized in Example 1 was added to 80 mL of a 10 mg / L Rhodamine B solution. Under magnetic stirring at 1000 rpm, the solution was allowed to adsorb in the dark for 1 hour. A xenon lamp (containing a 420 nm cutoff filter) was used as the light source. Samples were taken every 10 minutes, centrifuged, and the supernatant was collected. The absorbance was measured using a UV-9000S UV-Vis spectrophotometer. The results showed that the photocatalyst catalyzed the degradation of 99.9% of Rhodamine B within 30 min, proving that sunflower-shaped Bi... 24 O 31 Cl 10 It exhibits excellent photocatalytic performance; see appendix. Figure 3 (A)

[0034] 20 mg of the catalyst synthesized in Example 1 was added to 80 mL of a 20 mg / L bisphenol A solution. Under magnetic stirring at 1000 rpm, the solution was allowed to adsorb in the dark for 1 hour. A xenon lamp (containing a 420 nm cutoff filter) was used as the light source. Samples were taken every 10 minutes, centrifuged, and the supernatant was collected. The absorbance was measured using a UV-9000S UV-Vis spectrophotometer. The results showed that the photocatalyst catalyzed the degradation of 95% of bisphenol A within 30 minutes, proving that the sunflower-shaped Bi... 24 O 31 Cl 10 It exhibits high photocatalytic activity; see appendix. Figure 3 (B)

[0035] Take 5 mg of the catalyst synthesized in Example 1 and add it to 80 mL of 2×10 -5 In a mol / L 2-naphthol solution, under magnetic stirring at 1000 r / min, dark adsorption was carried out for 1 hour. A xenon lamp (with a 420 nm cutoff filter) was used as the light source. Samples were taken every 10 minutes after irradiation, centrifuged, and the supernatant was collected. The absorbance was measured using a UV-9000S UV-Vis spectrophotometer. The results showed that the photocatalyst catalyzed the degradation of 99% of 2-naphthol within 30 min, proving that sunflower-shaped Bi 24 O 31 Cl 10 It exhibits excellent photocatalytic activity; see appendix. Figure 3 (C).

[0036] 20 mg of the catalyst synthesized in Example 1 was added to 80 mL of a 20 mg / L tetracycline hydrochloride solution. Under magnetic stirring at 1000 rpm, the solution was allowed to adsorb in the dark for 1 hour. A xenon lamp (containing a 420 nm cutoff filter) was used as the light source. Samples were taken every 10 minutes, centrifuged, and the supernatant was collected. The absorbance was measured using a UV-9000S UV-Vis spectrophotometer. The results showed that the photocatalyst catalyzed the degradation of 97.5% of tetracycline hydrochloride within 30 min, proving that the sunflower-shaped Bi... 24 O 31 Cl 10 It exhibits excellent photocatalytic activity; see appendix. Figure 3 (D)

Claims

1. A sunflower-shaped Bi 24 O 31 Cl 10 Photocatalyst, characterized in that, The Bi 24 O 31 Cl 10 The photocatalyst has a particle size of 2-5 μm; the catalyst is Bi. 24 O 31 Cl 10 Sunflower-shaped structures formed by the self-assembly of nanosheets; The method for preparing the catalyst includes the following steps: (1) NaOH aqueous solution was added dropwise to BiCl3 ethanol solution, stirred evenly, and then heated to 90~140 °C for reaction. After repeated centrifugation, washing and drying, Bi was obtained. x O y Cl z Precursor; (2) The Bi described in step (1) x O y Cl z The precursor was ultrasonically and uniformly dispersed in ethylene glycol, transferred to a polytetrafluoroethylene reactor, and reacted at 180 °C. After repeated centrifugation, washing, and drying, sunflower-shaped Bi was obtained. 24 O 31 Cl 10 Photocatalyst.

2. A sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, The Bi 24 O 31 Cl 10 The thickness of the nanosheets is 5~20 nm.

3. The sunflower-shaped Bi according to claim 1 or 2 24 O 31 Cl 10 Photocatalyst, characterized in that, The molar ratio of BiCl3 and NaOH in step (1) is 1:4~6.

4. The sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, The reaction time described in step (1) is 8-16 hours.

5. The sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, The volume ratio of water in the NaOH aqueous solution and ethanol in the BiCl3 ethanol solution in step (1) is 1:

1.

6. The sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, Step (2) Bi x O y Cl z The mass-to-volume ratio of the precursor to ethylene glycol was 20:7 mg / mL.

7. The sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, The reaction time in step (2) is 0.5-2 hours.

8. The sunflower-shaped Bi according to claim 1 24 O 31 Cl 10 Photocatalyst, characterized in that, In both steps (1) and (2), deionized water and anhydrous ethanol are used for multiple washings; the drying in step (2) is: vacuum drying at 60°C for 12 hours.

9. The sunflower-shaped Bi as described in any one of claims 1-8 24 O 31 Cl 10 The application of photocatalysts is characterized by, The catalyst was used for the visible light catalytic degradation of organic pollutants in water.

10. The sunflower-shaped Bi according to claim 9 24 O 31 Cl 10 The application of photocatalysts is characterized by, The organic pollutant is rhodamine B, bisphenol A, 2-naphthol, or tetracycline hydrochloride.

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