An Ag-Bi 24 Br 10 O 31 / Bi2O2S heterojunction composite material and preparation method and application thereof

Abstract

This invention discloses an Ag-Bi 24 Br 10 O 31 This paper discusses the preparation and application of Bi₂O₂S heterojunction composite materials, belonging to the field of SERS detection technology. First, Bi₂O₂S heterojunction composite materials are prepared using a hydrothermal method. 24 Br 10 O 31 Nanosheets, then with Bi 24 Br 10 O 31 Bi2O2S was constructed by secondary hydrothermal in-situ growth of Bi2O2S on nanosheets as a substrate. 24 Br 10 O 31 A Bi₂O₂S heterostructure was formed, followed by chemical reduction to load Ag nanoparticles, and then dried to obtain the target composite SERS substrate. This material utilizes the localized surface plasmon effect of Ag to form a strong SERS "hot spot," exhibiting excellent Raman enhancement performance for crystal violet, enabling highly sensitive detection of crystal violet. This method is simple, uses readily available raw materials, and produces a material that combines excellent SERS enhancement performance with photocatalytic activity, showing broad application prospects in environmental monitoring and pollution control.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection technology, specifically relating to an Ag-Bi... 24 Br 10 O 31 / Bi2O2S heterojunction composite materials, their preparation methods and applications. Background Technology

[0002] With the rapid development of modern printing and dyeing, textile, and papermaking industries, a large number of synthetic organic dyes are widely produced and used. The unregulated discharge of dye-containing wastewater has become a significant source of water pollution. Crystal violet (CV), a typical triarylmethane cationic industrial basic dye, is chemically stable and difficult to biodegrade. Its long-term persistence in the aquatic environment not only disrupts the ecological balance of water bodies but also poses potential biotoxicity and carcinogenic risks, causing continuous harm to human health and ecosystems. Therefore, developing highly sensitive and rapid detection technologies for crystal violet pollutants is of significant practical importance for environmental risk early warning and water quality safety management.

[0003] While traditional dye detection methods offer high accuracy, they generally suffer from drawbacks such as expensive equipment, complex operation, long detection cycles, and insufficient on-site rapid detection capabilities. Surface-enhanced Raman scattering (SERS) technology, however, boasts significant advantages including high sensitivity, rapid response, strong fingerprint recognition, and non-destructive testing. During detection, relying on a sophisticated synergistic mechanism between the substrate and the analyte, they work together to form a highly efficient signal amplification system. This system can progressively strengthen and amplify the Raman signal of the molecules, making previously weak signals clearly discernible. With this unique advantage, SERS technology has shown immense application potential in the trace analysis of organic pollutants, providing a novel technical path to solve many problems faced by traditional detection methods and potentially driving a qualitative leap in dye detection and related fields.

[0004] Single semiconductor materials exhibit weak SERS enhancement capabilities, making it difficult to effectively recognize low-concentration dye molecules. Two-dimensional layered bismuth-based semiconductor materials possess unique layered structures, good visible light response, and excellent adsorption properties. Constructing semiconductor heterojunctions can effectively suppress photogenerated carrier recombination, further enhancing interfacial charge transfer efficiency. Introducing appropriate amounts of silver nanoparticles for modification allows for the construction of abundant SERS hotspots utilizing the localized surface plasmon resonance effect of silver, significantly improving Raman signal enhancement. This invention designs and prepares a silver-loaded Ag-Bi... 24 Br 10 O 31The / Bi2O2S layered composite SERS substrate, through the controllable loading of 1% to 3% silver nanoparticles, synergistic heterojunction interface regulation and plasma enhancement effect, achieves highly sensitive SERS detection of crystal violet dye in water over a wide concentration range. This overcomes the application limitations of single-function detection materials and provides new functional materials and technical support for the simultaneous detection and treatment of environmental organic dye pollutants. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention designs and synthesizes an Ag-Bi... 24 Br 10 O 31 / Bi2O2S composite SERS substrate. When this SERS substrate interacts with probe molecules, the controllable loading of 1% to 3% silver nanoparticles, combined with heterojunction interface modulation and plasma enhancement effects, enables efficient detection and analysis of chemical substances.

[0006] The technical solution adopted in this invention is: an Ag-Bi 24 Br 10 O 31 The preparation method of the / Bi2O2S heterojunction composite material includes the following steps:

[0007] 1) Bismuth nitrate was dissolved in ethylene glycol, and sodium bromide was dissolved in water. After mixing and stirring, Bi was obtained by hydrothermal method. 24 Br 10 O 31 Nanosheets;

[0008] 2) Combine thiourea and Bi 24 Br 10 O 31 Nanosheets are dissolved in ethylene glycol and subjected to in-situ hydrothermal sulfidation reaction in Bi 24 Br 10 O 31 Bi₂O₂S was grown on the surface, and Bi was obtained by centrifugation, washing, and drying. 24 Br 10 O 31 / Bi2O2S binary heterojunction composite material;

[0009] 3) Dissolve silver nitrate in deionized water, Bi 24 Br 10 O 31 The / Bi2O2S binary heterojunction composite material was dissolved in ethanol. After mixing the two, a dilute sodium borohydride solution was added dropwise to prepare Ag-Bi by chemical reduction. 24 Br 10 O 31 / Bi2O2S composite material;

[0010] 4) Centrifuge, wash, and dry the composite material obtained in step 3) to obtain Ag-Bi. 24 Br 10 O 31 / Bi2O2S heterojunction composite material.

[0011] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of the / Bi2O2S heterojunction composite material, in step 1), the molar ratio of bismuth nitrate and sodium bromide is 1:1.1.

[0012] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of / Bi2O2S heterojunction composite material, in step 1), the reaction temperature of the hydrothermal method is 140-160 ℃ and the reaction time is 10-12 h.

[0013] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of Bi2O2S heterojunction composite material, in step 2), Bi 24 Br 10 O 31 The mass ratio of nanosheets to thiourea is 5:1-1.5.

[0014] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of / Bi2O2S heterojunction composite material, in step 2), the reaction temperature of the in-situ hydrothermal sulfidation reaction is 120-140 ℃ and the reaction time is 5-6 h.

[0015] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of the / Bi2O2S heterojunction composite material, step 3) involves using sodium borohydride powder, silver nitrate, and Bi2O2S heterojunction composite material in the following mass ratio: 24 Br 10 O 31 The / Bi2O2S binary heterojunction composite material has a ratio of 2.5-3:3:100, and the concentration of the dilute sodium borohydride solution is 0.01-0.02 mol / L.

[0016] The above-mentioned Ag-Bi 24 Br 10 O 31 In the preparation method of the / Bi2O2S heterojunction composite material, step 3) describes a chemical reduction method involving stirring at room temperature for 0.5-1 h.

[0017] Ag-Bi prepared by the above preparation method 24 Br 10 O 31 / Bi2O2S heterojunction composite material.

[0018] The above-mentioned Ag-Bi 24 Br 10 O 31 Application of Bi2O2S heterojunction composite materials in industrial dye detection.

[0019] The above-mentioned Ag-Bi 24 Br 10 O 31 The application of / Bi2O2S heterojunction composite material in industrial dye detection, wherein the industrial dye is crystal violet, and the method for detecting crystal violet is as follows: under 532nm laser irradiation, the Ag-Bi 24 Br 10 O 31 The / Bi2O2S heterojunction composite material was immersed in a crystal violet solution, which enhanced the Raman signal of the crystal violet molecules, enabling the detection of crystal violet in water.

[0020] The Ag-Bi constructed in this invention 24 Br 10 O 31 The Bi₂O₂S composite SERS substrate effectively enhances the Raman spectra of CV molecules, facilitating their detection in water. The beneficial effects of this method can be attributed to the following three aspects:

[0021] 1. The loaded silver nanoparticles generate local surface plasmon resonance, constructing abundant SERS hotspots and significantly enhancing the Raman signal of CV molecules.

[0022] 2. Bi 24 Br 10 O 31 The / Bi2O2S heterojunction can promote charge transfer, strengthen the interaction between the SERS substrate and CV molecules, and effectively improve SERS performance.

[0023] 3. The layered heterojunction has a large specific surface area and strong adsorption capacity for crystal violet; the silver loading is controllable and the dispersion is good, resulting in high detection sensitivity and good stability. Attached Figure Description

[0024] Figure 1 It is Ag-Bi in Example 2 24 Br 10 O 31 XRD pattern of the / Bi2O2S composite substrate.

[0025] Figure 2 In Example 2, Ag-Bi was irradiated with a 532 nm laser. 24 Br 10 O 31 SERS spectra collected after eight random Raman detections of CV molecules on a / Bi2O2S composite substrate.

[0026] Figure 3 In Example 2, CV molecules were adsorbed onto Ag-Bi under different laser powers at a 532 nm laser. 24 Br 10 O 31 SERS spectrum on the / Bi2O2S composite substrate.

[0027] Figure 4 In Example 2, under a 532 nm laser, different concentrations of CV molecules were adsorbed onto Ag-Bi. 24 Br 10 O 31 SERS spectrum on the / Bi2O2S composite substrate. Detailed Implementation

[0028] To better understand the technical solution of the present invention, specific embodiments are provided for further detailed description, but the solution is not limited thereto.

[0029] Example 1

[0030] Bi 24 Br 10 O 31 The preparation method of Bi2O2S is as follows:

[0031] Dissolve 0.39 g of bismuth nitrate in 25 ml of ethylene glycol and stir until clear. Weigh 0.11 g of sodium bromide and dissolve it in 10 ml of deionized water. Slowly add the sodium bromide solution dropwise to the stirred bismuth nitrate solution, stirring continuously for 30 min. After mixing thoroughly, place the mixture in a reaction vessel and carry out a hydrothermal reaction at 160°C for 12 h. Centrifuge, wash twice with water and twice with alcohol, and dry at 60°C to obtain Bi. 24 Br 10 O 31 Nanosheets, for later use. Take 0.1g Bi 24 Br 10 O 31 Nanosheets were ultrasonically dispersed in 30 ml of ethylene glycol, and 0.023 g of thiourea was added and stirred until homogeneous. The mixture was then transferred to a reaction vessel and reacted at 140°C for 6 hours. 24 Br 10 O 31 Bi₂O₂S was grown on the surface, and Bi was obtained by centrifugation, washing and drying. 24 Br 10 O 31 / Bi2O2S heterojunction composite material, the centrifugation rate is 8000 r / min and the centrifugation time is 5 min.

[0032] Example 2

[0033] Ag-Bi 24 Br 10 O 31 The preparation method of the / Bi2O2S composite SERS substrate is as follows:

[0034] Take 0.1g of Bi prepared in Example 1 24 Br 10 O 31 Bi₂O₂S powder was dispersed in 20 ml of ethanol, and 3 mg of silver nitrate was dissolved in 10 ml of deionized water. After stirring evenly, the solution was added dropwise to the mixture. 24 Br 10 O 31 In an ethanol solution of / Bi₂O₂S, stir continuously in the dark for 30 min. Then, add 7-8 mL of 0.01 mol / L dilute sodium borohydride solution dropwise to the solution and stir at room temperature for 0.5-1 h until gray color appears. Centrifuge at 8000 r / min for 5 min, wash twice with water and twice with alcohol, and dry under vacuum at 40°C to obtain Ag-Bi 24 Br 10 O 31 / Bi2O2S heterojunction composite material, namely Ag-Bi 24 Br 10 O 31 / Bi2O2S composite SERS substrate.

[0035] Prepared Ag-Bi 24 Br 10 O 31 / Bi2O2S composite SERS substrates were immersed in CV solutions of different concentrations for 4 hours, and then air-dried at room temperature. The dried composite SERS substrates were then subjected to Raman scattering spectroscopy.

[0036] Example 3

[0037] Ag-Bi 24 Br 10 O 31 Characterization and performance testing of Bi2O2S composite SERS substrate:

[0038] The Ag-Bi prepared in Example 2 24 Br 10 O 31 The crystal structure of the / Bi2O2S composite SERS substrate was analyzed by X-ray diffraction. For the Ag-Bi prepared in Example 2...24 Br 10 O 31 / Bi2O2S composite SERS substrate, through Figure 1 The XRD characterization map clearly shows Bi 24 Br 10 O 31 The characteristic diffraction peaks of the Bi2O2S phase and the substrate showed good peak position matching, with no obvious impurity peaks, sharp peak shapes, and high crystallinity. A weak characteristic diffraction peak appeared near 44°, which highly coincided with the standard diffraction peak position of the (200) crystal plane of metallic silver. The weak diffraction peak intensity indicated that the loaded Ag nanoparticles were small in size and uniformly dispersed, but did not damage the original crystal structure of the substrate. This indicates that the Ag nanoparticles were successfully loaded onto the substrate surface prepared in Example 1, and could effectively construct SERS electromagnetic enhancement hotspots. This shows that a pure phase and highly crystalline Ag-Bi phase was successfully prepared by the secondary hydrothermal method and chemical reduction method. 24 Br 10 O 31 / Bi2O2S ternary heterojunction composite material.

[0039] Subsequently, using crystal violet (CV) as a probe molecule, the Ag-Bi prepared in Example 2 was excited under 0.5mW 532nm laser excitation. 24 Br 10 O 31 The performance of the / Bi2O2S composite SERS substrate was evaluated. The results are as follows: Figure 2-4 As shown, the composite substrate effectively amplifies the Raman signal of CV, enabling efficient detection of CV molecules in the aquatic environment. Details are as follows:

[0040] Using Raman spectroscopy, 0.05g of Ag-Bi prepared in Example 2 was analyzed. 24 Br 10 O 31 The / Bi2O2S composite SERS substrate was dissolved in 1 ml of water, and 50 μl of the substrate was immersed in 50 μl of water with a concentration of 10. -6 The CV solution was dried and then subjected to Raman spectroscopy under 0.5mW 532nm laser excitation. Figure 2 To conduct Raman spectroscopy on CV molecules at eight randomly selected sites on the composite SERS substrate, the results showed that the CV characteristic peaks in the eight spectra were in the same position, with stable peak shape and small differences in peak intensity, and no obvious fluctuations, indicating that the composite SERS substrate has good homogeneity, reproducibility and stability.

[0041] Using a Raman spectrometer at different laser powers of 0.5, 0.25, and 0.025 mW, the above method was applied to 10... - 4 The test was performed using a mol / L CV solution. Figure 3 The test results under different laser powers are shown. It is observed that the intensity of the CV characteristic peak increases regularly with the increase of laser power, and the peak position does not shift significantly. This indicates that the substrate has a stable signal response and strong anti-interference ability, and can obtain reliable Raman enhanced signals under different test conditions.

[0042] Using a Raman spectrometer under a 532 nm laser, 10... -3 ~10 -8 Raman enhancement signals of CV molecules at different concentrations (mol / L) were used to verify the enhanced activity of the composite substrate prepared in Example 2. Figure 4 As a base pair 10 -3 ~10 - 8 SERS response spectra of crystal violet at mol / L concentration gradients. Even at 10 -8 Even at low concentrations of mol / L, the characteristic Raman peaks of CV can still be clearly identified, indicating that this Ag-Bi 24 Br 10 O 31 The / Bi2O2S composite substrate exhibits high adsorption capacity and high SERS enhancement effect for CV molecules, with a wide detection range and low detection limit, enabling efficient and sensitive detection of trace crystal violet in the aquatic environment.

Claims

1. An Ag-Bi 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, Includes the following steps: 1) Bismuth nitrate was dissolved in ethylene glycol, and sodium bromide was dissolved in water. After mixing and stirring, Bi was obtained by hydrothermal method. 24 Br 10 O 31 Nanosheets; 2) Combine thiourea and Bi 24 Br 10 O 31 Nanosheets are dissolved in ethylene glycol and subjected to in-situ hydrothermal sulfidation reaction in Bi 24 Br 10 O 31 Bi₂O₂S was grown on the surface, and Bi was obtained by centrifugation, washing, and drying. 24 Br 10 O 31 / Bi2O2S binary heterojunction composite material; 3) Dissolve silver nitrate in deionized water, Bi 24 Br 10 O 31 The / Bi2O2S binary heterojunction composite material was dissolved in ethanol. After mixing the two and stirring in the dark, a dilute sodium borohydride solution was added dropwise to prepare Ag-Bi by chemical reduction. 24 Br 10 O 31 / Bi2O2S composite material; 4) Centrifuge, wash, and dry the composite material obtained in step 3) to obtain Ag-Bi. 24 Br 10 O 31 / Bi2O2S heterojunction composite material.

2. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 1), the molar ratio of bismuth nitrate to sodium bromide is 1:1.

1.

3. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 1), the reaction temperature of the hydrothermal method is 140-160 ℃, and the reaction time is 10-12 h.

4. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 2), Bi 24 Br 10 O 31 The mass ratio of nanosheets to thiourea is 5:1-1.

5.

5. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 2), the reaction temperature of the in-situ hydrothermal sulfidation reaction is 120-140℃, and the reaction time is 5-6 h.

6. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 3), the mass ratio of sodium borohydride powder to silver nitrate to Bi is as follows: 24 Br 10 O 31 The / Bi2O2S binary heterojunction composite material has a ratio of 2.5-3:3:100, and the concentration of the dilute sodium borohydride solution is 0.01-0.02 mol / L.

7. An Ag-Bi according to claim 1 24 Br 10 O 31 The method for preparing Bi2O2S heterojunction composite materials is characterized by, In step 3), the chemical reduction method involves stirring at room temperature for 0.5-1 hour.

8. An Ag-Bi prepared by the preparation method according to any one of claims 1-7 24 Br 10 O 31 / Bi2O2S heterojunction composite material.

9. An Ag-Bi as described in claim 8 24 Br 10 O 31 Application of Bi2O2S heterojunction composite materials in industrial dye detection.

10. The Ag-Bi according to claim 9 24 Br 10 O 31 The application of Bi2O2S heterojunction composite materials in industrial dye detection is characterized by... The industrial dye mentioned is crystal violet, and the method for detecting crystal violet is as follows: Under irradiation with a 532nm laser, the Ag-Bi... 24 Br 10 O 31 The / Bi2O2S heterojunction composite material was immersed in a crystal violet solution, which enhanced the Raman signal of the crystal violet molecules, enabling the detection of crystal violet in water.

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