A method for preparing a composite sers substrate and its application in industrial dye detection

Abstract

The application belongs to the technical field of SERS detection, and particularly relates to a preparation method of a composite SERS substrate and application thereof in industrial dye detection. Fe2O3 nanoparticles are prepared by a hydrothermal method; indium sulfide tetrahydrate, thioacetamide and the Fe2O3 nanoparticles are added into water, and In2S3@Fe2O3 composite materials are obtained by a secondary hydrothermal method; sodium citrate is dissolved in water, silver nitrate and the In2S3@Fe2O3 composite materials are added, Ag nanoparticles are reduced on the surface of the In2S3@Fe2O3 composite materials by a chemical reduction method, and Ag@In2S3@Fe2O3 composite SERS substrates are obtained by drying. By integrating the local surface plasmon resonance effect of Ag nanoparticles, the charge separation ability of In2S3 and the surface active sites of Fe2O3, an efficient interface charge transfer channel is constructed, and the Raman signal of RB molecules is enhanced. The substrate has electromagnetic enhancement and chemical enhancement synergistic effect, and realizes high-sensitivity and specificity detection of trace RB.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection technology, specifically relating to a method for preparing a composite SERS substrate and its application in industrial dye detection. Background Technology

[0002] The widespread use of industrial dyes has made organic pollutants such as RB a growing threat to aquatic ecosystems. These persistent, bioaccumulative, and highly toxic dye pollutants not only deteriorate the sensory properties of water bodies but also cause profound harm to aquatic organisms and human health through bioaccumulation in the food chain. To address this significant environmental challenge, the development of bifunctional nanomaterials with both high-sensitivity real-time detection and efficient catalytic degradation has become a research hotspot in the field of environmental governance. SERS technology, as a groundbreaking molecular fingerprinting technology, has attracted widespread attention due to its significant advantages, including ultra-high detection sensitivity at the single-molecule level; no need for complex sample pretreatment; rich molecular vibrational fingerprint information enabling specific molecular recognition; good resistance to photobleaching, suitable for long-term in-situ monitoring; and weak response to water molecules, making it particularly suitable for water environment monitoring. These unique advantages make it valuable for applications in trace detection of environmental pollutants, food safety monitoring, and biomedical diagnostics.

[0003] The signal enhancement effect of SERS technology mainly stems from the synergistic effect of electromagnetic and chemical enhancement. Electromagnetic field enhancement induced by localized plasmon resonance on the surface of metal nanostructures is the dominant mechanism, and its enhancement effect strongly depends on the precise control of the nanoparticle geometry, spatial arrangement, and inter-particle spacing. Chemical enhancement, on the other hand, achieves relatively weak signal amplification through charge transfer between molecules and the substrate. Although traditional gold and silver noble metal substrates are widely used due to their excellent plasmon properties, their high cost and susceptibility to oxidation and deactivation severely limit their practical application. This has prompted researchers to develop metal-semiconductor composite substrate materials, which, by integrating the advantages of plasmon resonance and semiconductor bandgap modulation, provide a new solution for achieving stable and efficient ultra-trace detection.

[0004] Leveraging the superior properties of Ag nanoparticles, In₂S₃, and Fe₂O₃, a ternary composite SERS substrate was constructed. This substrate significantly enhances the Raman signal of RB molecules through interfacial charge transfer effects, enabling highly sensitive detection of RB pollutants in environmental samples and possessing significant value for environmental monitoring applications. This composite system utilizes the localized surface plasmon resonance effect of Ag nanoparticles, the efficient charge separation capability of In₂S₃, and the surface active sites of Fe₂O₃ to form enhanced charge transfer channels at the three-phase interface, thereby significantly enhancing the chemical activity of RB molecules. This novel SERS substrate provides an innovative solution for the rapid detection of trace organic pollutants in environmental water bodies and will have significant implications for the environmental field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention designs and synthesizes an Ag@In2S3@Fe2O3 composite SERS substrate. When this SERS substrate interacts with probe molecules, the intrinsic Raman signal of the target molecule is significantly enhanced through an interfacial charge transfer mechanism, thereby achieving efficient detection and analysis of chemical substances.

[0006] The technical solution adopted in this invention is: an Ag@In2S3@Fe2O3 composite SERS substrate, the preparation method of which includes the following steps:

[0007] 1) Fe2O3 nanoparticles were obtained by dissolving ferric chloride hexahydrate and sodium hydroxide in water and using a hydrothermal method.

[0008] 2) Indium sulfide tetrahydrate, thioacetamide and Fe2O3 nanoparticles were added to water, and In2S3@Fe2O3 composite material was obtained by secondary hydrothermal method;

[0009] 3) Dissolve sodium citrate powder in water, add silver nitrate and In2S3@Fe2O3 composite material, and use chemical reduction method to reduce Ag nanoparticles on the surface of In2S3@Fe2O3 composite material; prepare Ag@In2S3@Fe2O3 composite material.

[0010] 4) The composite material obtained in step 3) is dried to obtain the Ag@In2S3@Fe2O3 composite SERS substrate.

[0011] In the Ag@In2S3@Fe2O3 composite SERS substrate mentioned above, in step 1), the mass ratio of ferric chloride hexahydrate to sodium hydroxide is 2-3:1.

[0012] In the Ag@In2S3@Fe2O3 composite SERS substrate mentioned above, in step 1), the hydrothermal reaction temperature is 160-180 ℃ and the hydrothermal time is 8-10 h.

[0013] In the Ag@In2S3@Fe2O3 composite SERS substrate mentioned above, in step 2), the mass ratio of indium sulfide tetrahydrate, thioacetamide, and Fe2O3 nanoparticles is 2-3:1-2:1.

[0014] In the Ag@In2S3@Fe2O3 composite SERS substrate mentioned above, in step 2), the hydrothermal reaction temperature is 120-140 ℃ and the hydrothermal time is 12-14 h in the secondary hydrothermal method.

[0015] In step 3) of the Ag@In2S3@Fe2O3 composite SERS substrate mentioned above, the mass ratio of sodium citrate powder: silver nitrate: In2S3@Fe2O3 is 2-3:1-2:1.

[0016] In step 3) of the aforementioned Ag@In2S3@Fe2O3 composite SERS substrate, the chemical reduction method is carried out at a speed of 500 rpm, a temperature of 100-110 ℃, and stirring for 0.5-1 h.

[0017] In the Ag@In2S3@Fe2O3 composite SERS substrate described above, in step 4), the drying temperature is 50-60℃ and the drying time is 3-4 h.

[0018] The above-mentioned Ag@In2S3@Fe2O3 composite SERS substrate is used for the detection of RB molecules in water.

[0019] The above application is performed as follows: Under 532nm laser irradiation, the Ag@In2S3@Fe2O3 composite SERS substrate is immersed in RB solution, which enhances the Raman signal of RB molecules, and RB molecules are detected in water.

[0020] This invention utilizes a constructed Ag@In2S3@Fe2O3 composite SERS substrate to enhance the Raman spectrum of RB molecules, facilitating their detection in water. The beneficial effects of this method can be attributed to two aspects:

[0021] 1. The Ag@In2S3@Fe2O3 ternary heterostructure achieves a multi-component synergistic enhancement effect through metal-semiconductor interface engineering: Ag nanoparticles provide strong local surface plasmon resonance, the narrow bandgap characteristics of In2S3 promote electronic excitation in the visible light region, and the surface hydroxyl sites of Fe2O3 effectively anchor RB molecules. The three synergistically enhance the SERS signal.

[0022] 2. The Ag@In2S3@Fe2O3 composite system innovatively constructs a three-dimensional charge transport network: In2S3 and Fe2O3 form a heterojunction, and Ag nanoparticles act as electron relays, which can improve the interface charge transfer efficiency and thus enhance the SERS signal of RB molecules. Attached Figure Description

[0023] Figure 1 This is a SEM image of the Ag@In2S3@Fe2O3 composite substrate in Example 1.

[0024] Figure 2 This is the XRD pattern of the Ag@In2S3@Fe2O3 composite substrate in Example 1.

[0025] Figure 3 These are the Raman spectra of RB molecules under a 532 nm laser in Example 1, and the SERS spectra of R6G molecules adsorbed on the Ag@In2S3@Fe2O3 composite substrate.

[0026] Figure 4 This is the SERS spectrum collected in Example 1 after randomly performing 12 Raman detections on the RB molecules using a 532 nm laser irradiation on the Ag@In2S3@Fe2O3 composite substrate.

[0027] Figure 5 This is the SERS spectrum of RB molecules adsorbed on the Ag@In2S3@Fe2O3 composite substrate under 532 nm laser light in Example 1 without laser power.

[0028] Figure 6 This is the SERS spectrum of different concentrations of RB molecules adsorbed on the Ag@In2S3@Fe2O3 composite substrate under 532 nm laser light in Example 1. Detailed Implementation

[0029] 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.

[0030] Example 1: An Ag@In2S3@Fe2O3 composite SERS substrate

[0031] The preparation method is as follows:

[0032] 1) Add 1.4 g of ferric chloride hexahydrate and 0.54 g of sodium hydroxide to 80 mL of water, then transfer the mixed solution to a high-pressure reactor and maintain it at 180 °C for 8 h. After cooling to room temperature, centrifuge, wash, and dry for later use.

[0033] 2) Add 220 mg of indium sulfide tetrahydrate, 112.8 mg of thioacetamide, and 100 mg of Fe2O3 nanoparticles to 45 mL of water, keep at 120 °C for 12 h, cool to room temperature, centrifuge, wash, and dry for later use.

[0034] 3) Add 20 mg sodium citrate, 10 mg In2S3@Fe2O3 composite material and 18 mg silver nitrate to a round-bottom flask containing 100 mL deionized water. Heat to 100 °C and stir for 1 hour at 500 rpm. After cooling to room temperature, centrifuge, wash and dry for later use.

[0035] 4) The prepared Ag@In2S3@Fe2O3 composite SERS substrate was immersed in RB solution for 4 h and then air-dried at room temperature for later use.

[0036] The Ag@In2S3@Fe2O3 composite SERS substrate prepared in step 1) was subjected to SEM testing, and the test results are as follows: Figure 1 As shown in the figure, Ag nanoparticles are uniformly dispersed on the In2S3@Fe2O3 surface, indicating the successful preparation of the Ag@In2S3@Fe2O3 composite SERS substrate. XRD tests were performed on the Ag@In2S3@Fe2O3 composite substrates prepared in steps 1) and 2), and the results are shown below. Figure 2 As shown in the figure, the Ag@In2S3@Fe2O3 composite substrate was successfully prepared. The Ag@In2S3@Fe2O3 composite SERS substrate prepared in Example 1 was used to conduct experiments based on SERS technology using RB as a probe molecule. The testing procedure was as follows: a 532 nm wavelength laser was used as the excitation source, and RB was used as a probe molecule on the Ag@In2S3@Fe2O3 composite SERS substrate based on SERS technology. Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the Ag@In2S3@Fe2O3 composite SERS substrate prepared in Example 1 can enhance the Raman signal of RB molecules, facilitating the detection of RB molecules in water. Furthermore, 10 random Raman tests were performed on the Ag@In2S3@Fe2O3 composite substrate, revealing uniform Raman signal peaks and no significant changes in Raman intensity, indicating that the Ag@In2S3@Fe2O3 composite SERS substrate possesses good uniformity and reproducibility. In addition, the detection of RB molecules on the Ag@In2S3@Fe2O3 composite substrate was conducted at different laser powers, demonstrating the excellent enhancement effect of this Ag@In2S3@Fe2O3 composite SERS substrate. The prepared Ag@In2S3@Fe2O3 composite SERS substrate can detect RB molecules of different concentrations, and can still perform highly sensitive detection even at extremely low RB molecule concentrations.

Claims

1. An Ag@In2S3@Fe2O3 composite SERS substrate, characterized in that, Its preparation method includes the following steps: 1) Dissolve ferric chloride hexahydrate and sodium hydroxide in water and carry out a hydrothermal reaction at 160-180℃ for 8-10 hours to obtain Fe2O3 nanoparticles; 2) Indium sulfide tetrahydrate, thioacetamide and Fe2O3 nanoparticles were added to water and subjected to a hydrothermal reaction at 120-140℃ for 12-14h to obtain In2S3@Fe2O3 composite material; 3) Dissolve sodium citrate powder in water, add silver nitrate and In2S3@Fe2O3 composite material, and use chemical reduction method to reduce Ag nanoparticles on the surface of In2S3@Fe2O3 composite material to obtain Ag@In2S3@Fe2O3 composite material. 4) The composite material obtained in step 3) is dried to obtain the Ag@In2S3@Fe2O3 composite SERS substrate.

2. The Ag@In2S3@Fe2O3 composite SERS substrate according to claim 1, characterized in that, In step 1), the mass ratio of ferric chloride hexahydrate to sodium hydroxide is 2-3:

1.

3. The Ag@In2S3@Fe2O3 composite SERS substrate according to claim 1, characterized in that, In step 2), the mass ratio of indium sulfide tetrahydrate, thioacetamide, and Fe2O3 nanoparticles is 2-3:1-2:

1.

4. The Ag@In2S3@Fe2O3 composite SERS substrate according to claim 1, characterized in that, In step 3), the mass ratio of sodium citrate powder: silver nitrate: In2S3@Fe2O3 is 2-3:1-2:

1.

5. The Ag@In2S3@Fe2O3 composite SERS substrate according to claim 1, characterized in that, In step 3), the chemical reduction method is carried out at a speed of 500 rpm, a temperature of 100-110 ℃, and stirring for 0.5-1 h.

6. The Ag@In2S3@Fe2O3 composite SERS substrate according to claim 1, characterized in that, In step 4), the drying temperature is 50-60℃ and the drying time is 3-4 hours.

7. The application of the Ag@In2S3@Fe2O3 composite SERS substrate according to any one of claims 1-6 in the detection of RB molecules in water.

8. The application according to claim 7, characterized in that, The method is as follows: Under 532nm laser irradiation, the Ag@In2S3@Fe2O3 composite SERS substrate was immersed in RB solution, which enhanced the Raman signal of RB molecules, and RB molecules were detected in water.

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