A silver-titanate composite surface-enhanced raman scattering substrate, and a preparation method and application thereof

Abstract

The application belongs to the technical field of surface enhanced Raman scattering (SERS) detection, and relates to a silver-titanate composite surface enhanced Raman scattering substrate and a preparation method and application thereof. First, barium chloride and titanium tetrachloride are used as raw materials to prepare a titanate material through a hydrothermal method; then, silver nanoparticles are prepared by a chemical reduction method and are loaded on the surface of the titanate to obtain a silver-titanate composite SERS substrate. The composite substrate can effectively improve the dispersion degree of the silver nanoparticles, increase the number of active sites, and improve the adsorption state of target molecules on the surface of the substrate, thereby significantly enhancing the Raman response signal of mercaptobenzoic acid. Compared with silver nanoparticles alone, the constructed silver-titanate composite substrate has higher detection sensitivity, good uniformity and repeatability, can be used for rapid detection and analysis of trace organic small molecules, and has good application prospects in the fields of environmental monitoring and chemical analysis.

Description

Technical Field

[0001] This invention belongs to the field of surface-enhanced Raman scattering detection technology, specifically relating to a silver-titanium composite surface-enhanced Raman scattering substrate, its preparation method, and its application. Background Technology

[0002] p-Mercaptobenzoic acid is a typical aromatic sulfur-containing organic compound with wide applications in pharmaceutical synthesis, fine chemicals, functional material preparation, and surface modification. Due to the presence of both thiol and carboxyl functional groups in its molecular structure, it exhibits strong coordination ability and surface adsorption properties. In actual production and use, p-Mercaptobenzoic acid may enter water bodies or other environmental media; therefore, establishing sensitive, rapid, and reliable detection methods is of great significance for related research and applications.

[0003] Raman spectroscopy has attracted widespread attention due to its ease of operation, small sample requirements, and strong molecular fingerprint recognition capabilities. However, ordinary Raman scattering signals are weak, limiting its ability to detect low-concentration target molecules. Surface-enhanced Raman scattering (SERS) technology, by constructing substrate materials with enhancement effects, can significantly improve the Raman signal intensity of target molecules, thereby achieving highly sensitive detection of trace substances. Currently, silver nanoparticles are considered one of the most commonly used active materials for SERS due to their excellent local electromagnetic field enhancement capabilities. However, silver nanoparticles are prone to aggregation during preparation and use, leading to uneven distribution of active sites, which affects the stability and repeatability of detection results.

[0004] In recent years, researchers have discovered that combining metal nanoparticles with functional oxide materials is an important way to improve SERS performance. Titanate materials possess high chemical and structural stability, as well as abundant surface active sites and good dispersing support properties. By constructing a composite structure of silver nanoparticles and titanates, not only can the dispersion of silver nanoparticles be improved, but the contact interface between target molecules and the substrate can also be increased, thereby enhancing detection performance.

[0005] Current research on silver-titanium composites in surface-enhanced Raman spectroscopy (SERS) is limited, particularly regarding the detection of mercaptobenzoic acid. Therefore, developing a simple-to-prepare, stable, and highly reinforcing silver-titanium composite SERS substrate is of great significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a silver-titanium composite surface-enhanced Raman scattering substrate, its preparation method, and its applications. This composite material utilizes a titanate support to effectively disperse silver nanoparticles, increasing the number of active interfaces and enhancing the Raman response signal of target molecules, thereby achieving highly sensitive detection of mercaptobenzoic acid.

[0007] The technical solution adopted in this invention is a method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, which includes the following steps.

[0008] 1) Dissolve the barium salt in deionized water to form a homogeneous solution.

[0009] 2) Add a titanium source to the solution obtained in step 1) under stirring conditions and continue stirring to form a precursor system.

[0010] 3) The precursor system is transferred to a reactor for hydrothermal reaction. After the reaction is completed, the titanium dioxide material is obtained by washing and drying.

[0011] 4) Silver nanoparticle dispersion was prepared by chemical reduction method.

[0012] 5) Add titanate material to silver nanoparticle dispersion, and then disperse and stir to form composite.

[0013] 6) After drying the obtained product, a silver-titanium composite surface-enhanced Raman scattering substrate is obtained.

[0014] In the above-mentioned method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, in steps 1) and 2), the molar ratio of barium salt to titanium source is 1.0 to 1.3:1, wherein the barium salt is barium chloride and the titanium source is titanium tetrachloride.

[0015] In the above-mentioned method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, step 3) involves a hydrothermal reaction temperature of 220–260 °C and a reaction time of 8–16 h.

[0016] In the above-mentioned method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, step 3) involves washing with deionized water and ethanol alternately 2 to 5 times, and drying at 50 to 80°C for 10 to 14 hours.

[0017] In the above-mentioned method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, step 4) uses sodium citrate as a reducing agent to prepare a silver nanoparticle dispersion by chemical reduction. Specifically, a silver nitrate solution is prepared, heated to boiling under stirring, clarified, and then sodium citrate solution is added. The reaction is carried out under stirring and slight boiling conditions, and the silver nanoparticle dispersion is obtained by cooling.

[0018] In the above-mentioned method for preparing a silver-titanium composite surface-enhanced Raman scattering substrate, step 5) involves ultrasonication for 10–40 min and stirring for 1–4 h.

[0019] A silver-titanium composite surface-enhanced Raman scattering substrate prepared according to the above preparation method.

[0020] Application of the above-mentioned silver-titanium composite surface-enhanced Raman scattering substrate in the detection of p-thiobenzoic acid.

[0021] In the above application, a 532nm laser is used as the excitation source. The silver-titanium composite surface-enhanced Raman scattering substrate loaded with p-mercaptobenzoic acid is immersed in a p-mercaptobenzoic acid solution for 2 hours. After removal and drying, the silver-titanium composite substrate is subjected to Raman detection to achieve qualitative or quantitative analysis of p-mercaptobenzoic acid.

[0022] Compared with the prior art, the present invention has the following beneficial effects.

[0023] 1. By combining titanate carriers with silver nanoparticles, uniform loading of silver nanoparticles on the carrier surface was achieved, effectively inhibiting the aggregation of silver nanoparticles and increasing the exposure of active sites.

[0024] 2. Titanate materials can provide more adsorption sites for target molecules, making it easier for mercaptobenzoic acid to accumulate in the enhancement region, thereby improving the coupling efficiency between the target molecule and the local enhanced electromagnetic field and thus obtaining a stronger SERS response signal.

[0025] 3. The composite structure improves the spatial distribution uniformity of hot spots on the substrate surface, reduces signal fluctuations between different test areas, and gives the resulting substrate good uniformity and repeatability.

[0026] 4. The silver-titanium composite substrate constructed in this invention can achieve sensitive detection of p-mercaptobenzoic acid and has a good concentration response relationship, which can be used for qualitative and quantitative analysis of trace p-mercaptobenzoic acid.

[0027] 5. The preparation process of this invention is simple, low-cost, and highly reproducible. The resulting composite substrate has high stability and has good application prospects in environmental monitoring, chemical analysis, and trace organic pollutant detection. Attached Figure Description

[0028] Figure 1 XRD pattern of silver-titanium composite surface-enhanced Raman scattering substrate.

[0029] Figure 2 The images show the SERS spectra of p-thiol benzoic acid adsorbed on silver nanoparticles and silver-titanium composite surface-enhanced Raman scattering substrates, respectively.

[0030] Figure 3 SERS spectra of different concentrations of p-thiobenzoic acid adsorbed on a silver-titanium composite surface enhanced Raman scattering substrate.

[0031] Figure 4SERS spectra were obtained from 10 randomly selected test points on a silver-titanium composite substrate to enhance the Raman scattering of mercaptobenzoic acid.

[0032] Figure 5 for Figure 4 1583cm -1 Statistical results of characteristic peak intensity and analysis of relative standard deviation. Detailed Implementation

[0033] 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.

[0034] Example 1: Preparation of silver-titanium composite surface-enhanced Raman scattering substrate.

[0035] The preparation method is as follows.

[0036] 1) Weigh 1.13g of barium chloride and add it to 60mL of deionized water. Stir at room temperature until completely dissolved.

[0037] 2) Slowly add 0.60 mL of titanium tetrachloride under continuous stirring, and continue stirring for 30 min to form a homogeneous reaction system.

[0038] 3) Transfer the obtained mixture to a polytetrafluoroethylene-lined reactor and hydrothermally react at 240°C for 12 hours.

[0039] 4) After the reaction is complete and the mixture is naturally cooled to room temperature, it is ultrasonically washed three times with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain titanate material.

[0040] 5) A silver nanoparticle dispersion was prepared using the sodium citrate reduction method. 0.017 g of silver nitrate (AgNO3) was weighed and added to 100 mL of deionized water. The mixture was heated to boiling under magnetic stirring. After the solution became completely clear, 2 mL of a 1% (w / w) sodium citrate solution was quickly added, and the reaction was maintained with continuous stirring and a gentle boil for 30 min. As the reaction proceeded, the solution color gradually changed from colorless to light yellow, eventually becoming a uniform yellow, indicating the formation of silver nanoparticles. After the reaction was complete, heating was stopped, and the solution was allowed to cool naturally to room temperature to obtain the silver nanoparticle dispersion.

[0041] 6) Add the titanate material obtained in step 4) to the silver nanoparticle dispersion obtained in step 5), sonicate for 30 min, and then stir for 2 h.

[0042] 7) The composite product was dried at 60°C for 4 hours to obtain a silver-titanium composite surface-enhanced Raman scattering substrate.

[0043] The obtained samples were subjected to XRD testing, and the results are as follows: Figure 1 As shown. By Figure 1 The obtained sample has obvious diffraction peaks, indicating that the prepared material has good crystallinity, which shows that the silver-titanium composite surface-enhanced Raman scattering substrate was successfully prepared.

[0044] Comparative Example 1: Silver nanoparticle substrate.

[0045] The silver nanoparticle dispersion obtained in step 5) of Example 1 was dried to obtain a silver nanoparticle substrate.

[0046] Example 2: Test on the enhancement performance of silver-titanium acid composite surface-enhanced Raman scattering substrate for p-thiobenzoic acid.

[0047] The steps are as follows.

[0048] The silver-titanium composite surface-enhanced Raman scattering substrate prepared in Example 1 and the single silver nanoparticle substrate obtained in Comparative Example 1 were respectively immersed in a solution of 10... -4 Soak in a mol / L solution of p-mercaptobenzoic acid for 2 hours, then remove and air dry for later use.

[0049] Raman spectroscopy was performed using a 532nm laser as the excitation source.

[0050] Test results are as follows Figure 2 As shown, compared with silver nanoparticles alone, the characteristic peak intensity of p-thiobenzoic acid on the silver-titanium composite surface-enhanced Raman scattering substrate is significantly improved, indicating that the introduction of titanate can effectively enhance the Raman response signal and improve the detection sensitivity.

[0051] Example 3: Concentration dependence and uniformity test.

[0052] (a) Concentration-dependent test.

[0053] The steps are as follows.

[0054] The concentrations were configured as follows: 10 -4 10 -5 10 -6 and 10 -7 A mol / L solution of p-mercaptobenzoic acid.

[0055] The silver-titanium composite surface-enhanced Raman scattering substrates prepared in Example 1 were immersed in the above solution for 2 hours, removed and air-dried, and then Raman detection was performed under the same test conditions.

[0056] The results are as follows Figure 3 As shown, the intensity of its characteristic peak gradually weakens as the concentration of mercaptobenzoic acid decreases, indicating a significant correlation between the Raman response and the concentration of the target molecule, suggesting that the substrate has good concentration response capability.

[0057] (ii) Uniformity test.

[0058] Subsequently, Raman tests were performed on 10 points randomly selected from different regions on the same silver-titanium composite substrate surface.

[0059] Test results are as follows Figure 4 As shown, the characteristic peak positions obtained at each test point are basically consistent, and the peak intensity fluctuations are small, indicating that the prepared silver-titanium composite surface-enhanced Raman scattering substrate has good uniformity and repeatability, which can meet the needs of practical detection applications.

[0060] Further Figure 4 1583cm -1 Statistical analysis of the characteristic peak intensity at the location was performed, and the results are as follows: Figure 5 As shown. The relative standard deviation (RSD) of the peak intensity at 10 randomly selected test points was calculated. The results show that 1583 cm⁻¹... -1 The relative standard deviation of the characteristic peaks is less than 10%, indicating that the active sites on the prepared silver-titanium composite surface-enhanced Raman scattering substrate are relatively uniformly distributed, and stable Raman response signals can be obtained at different test locations, demonstrating good uniformity and repeatability.

[0061] In summary, the silver-titanium composite surface-enhanced Raman scattering substrate provided by this invention has the advantages of simple preparation, significant enhancement effect, good uniformity and high repeatability, and can be used for highly sensitive detection of small organic molecules such as mercaptobenzoic acid.

Claims

1. The application of a silver-titanium composite surface-enhanced Raman scattering substrate in the detection of p-mercaptobenzoic acid, characterized in that, The preparation method of silver-titanium composite surface-enhanced Raman scattering substrate includes the following steps: 1) Dissolve the barium salt in deionized water to form a homogeneous solution; 2) Add a titanium source to the solution obtained in step 1) under stirring conditions and continue stirring to form a precursor system; the molar ratio of barium salt to titanium source is 1.0 to 1.3:1; 3) The precursor system is transferred to a reactor for hydrothermal reaction. After the reaction, the precursor is washed and dried to obtain titanate material. The hydrothermal reaction temperature is 220-260℃ and the reaction time is 8-16h. The washing is performed by alternating washing with deionized water and ethanol 2-5 times. The drying is performed at 50-80℃ for 10-14h. 4) Using sodium citrate as a reducing agent, a silver nanoparticle dispersion was prepared by chemical reduction. The specific method was to prepare a silver nitrate solution, heat it to boiling under stirring, clarify it, add sodium citrate solution, and react it under stirring and gentle boiling conditions. After cooling, a silver nanoparticle dispersion was obtained. 5) Add titanate materials to silver nanoparticle dispersion, and then combine them by ultrasonic dispersion and stirring; 6) After drying the obtained product, a silver-titanium composite surface-enhanced Raman scattering substrate is obtained.

2. The application of the silver-titanium composite surface-enhanced Raman scattering substrate according to claim 1 in the detection of p-mercaptobenzoic acid, characterized in that, In steps 1) and 2), the barium salt is barium chloride, and the titanium source is titanium tetrachloride.

3. The application of the silver-titanium composite surface-enhanced Raman scattering substrate according to claim 1 in the detection of p-mercaptobenzoic acid, characterized in that, In step 5), the ultrasonic time is 10-40 min and the stirring time is 1-4 h.

4. The application of the silver-titanium composite surface-enhanced Raman scattering substrate according to claim 1 in the detection of p-mercaptobenzoic acid, characterized in that, Using a 532nm laser as the excitation source, a silver-titanium composite surface-enhanced Raman scattering substrate was immersed in a solution of mercaptobenzoic acid for 2 hours. After removal and drying, Raman detection was performed to achieve the detection of mercaptobenzoic acid.

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