A surface-enhanced raman substrate for growing a titanium dioxide nanofilm on an aluminum base material, a preparation method and application thereof
By growing an aluminum oxide thin film on an aluminum substrate and then growing a titanium dioxide nanofilm in situ on its surface, the instability problem of the SERS substrate material was solved, achieving high signal reproducibility and long-term stability, and enhancing the Raman signal effect.
Patent Information
- Application Number
- CN202410240655.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-04
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2044-03-04
AI Technical Summary
The nanoparticles in existing SERS substrate materials are unstable, resulting in poor signal reproducibility and the inability to be stored for long periods.
An aluminum oxide thin film is grown on an aluminum substrate, and a titanium dioxide nanofilm is grown in situ on its surface. Through the interaction between the titanium dioxide nanofilm and the aluminum oxide film, a uniform surface defect state is formed, which enhances the Raman signal and prevents the aggregation of nanoparticles.
It achieves surface-enhanced Raman spectroscopy with high signal reproducibility and long-term stability, thus extending the storage time of the substrate.
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Figure CN118028733B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of surface-enhanced Raman scattering substrate, and particularly relates to a surface-enhanced Raman scattering substrate with a titanium dioxide nanofilm grown on an aluminum base and a preparation method and application thereof. BACKGROUND
[0002] Surface-enhanced Raman scattering (SERS) spectrum can enhance the signal of target molecules or groups in extremely complex systems, so as to obtain simple and clear spectral information and realize molecular fingerprint identification. In recent years, SERS has been widely concerned in the fields of analytical chemistry, biological science, food safety, environmental monitoring and the like due to its advantages such as rapid detection, non-destructive and the like.
[0003] At present, the SERS enhancement mechanism generally accepted by researchers mainly includes electromagnetic enhancement mechanism and chemical enhancement mechanism: the former considers that when light is incident on a metal surface, surface plasmon resonance occurs on the rough metal surface, so that the local electric field is enhanced, and the molecules close to the rough surface are affected by the strong electric field and produce strong Raman scattering; the latter considers that the measured molecules are combined with the Raman-active material through chemical bonds, and under the action of incident light, charge transfer occurs between the two, which affects the electron cloud density on the surface of the molecules, and then the polarizability of the molecules changes, thereby enhancing the Raman signal.
[0004] Whether SERS signal can be generated and its strength depend on the substrate material. SERS active substrate has experienced a development process from metal material to semiconductor material and then to composite material. The preparation of the substrate and the enhancement mechanism have always been the focus of attention. The traditional sol form SERS substrate preparation method is simple, has good repeatability, and the related research is relatively mature. However, the nanoparticles in the sol are unstable and easy to aggregate, and cannot be stored for a long time. SUMMARY
[0005] In order to solve the problems in the prior art, the present application provides a surface-enhanced Raman scattering substrate with a titanium dioxide nanofilm grown on an aluminum base and a preparation method and application thereof. The surface-enhanced Raman scattering substrate provided by the present application has the characteristics of high signal reproducibility and long-term stability.
[0006] In order to achieve the above purpose, the present application provides the following technical solutions.
[0007] The present application provides a surface-enhanced Raman scattering substrate with a titanium dioxide nanofilm grown on an aluminum base, which comprises an aluminum base, an aluminum oxide film on the surface of the aluminum base, and a titanium dioxide nanofilm on the surface of the aluminum oxide film.
[0008] Preferably, the thickness of the aluminum oxide film is 35-60 nm.
[0009] Preferably, the thickness of the titanium dioxide nanofilm is 600-900 nm.
[0010] The application further provides a preparation method of the surface-enhanced Raman substrate, comprising the following steps:
[0011] oxidizing the aluminum substrate to obtain an aluminum substrate with an alumina film on the surface;
[0012] mixing a tetrabutyl titanate anhydrous ethanol solution and a nitric acid ethanol solution to obtain a sol through hydrolysis;
[0013] placing the aluminum substrate with the alumina film on the surface in the sol, growing titanium dioxide on the surface of the alumina film in situ, and calcining to obtain the surface-enhanced Raman substrate.
[0014] Preferably, the tetrabutyl titanate anhydrous ethanol solution comprises tetrabutyl titanate and anhydrous ethanol, and the volume ratio of the tetrabutyl titanate to the anhydrous ethanol is 1-7:5.
[0015] Preferably, the preparation of the nitric acid ethanol solution is as follows:
[0016] mixing deionized water, concentrated nitric acid and anhydrous ethanol to obtain the nitric acid ethanol solution.
[0017] Preferably, the temperature for growing the titanium dioxide in situ is 140-180℃, and the holding time is 4-8 h.
[0018] Preferably, the calcination temperature is 400-600℃, and the holding time is 1-4 h.
[0019] Preferably, the oxidation is natural oxidation, and the natural oxidation is to place the aluminum substrate in air at room temperature for more than 24 h.
[0020] The application further provides application of the surface-enhanced Raman substrate prepared by the preparation method in surface-enhanced Raman scattering.
[0021] The application provides a surface-enhanced Raman substrate with a titanium dioxide nanofilm grown on an aluminum base, comprising an aluminum base, an aluminum oxide film on the surface of the aluminum base, and a titanium dioxide nanofilm on the surface of the aluminum oxide film. BRIEF DESCRIPTION OF DRAWINGS
[0022] Figure 1 A structure diagram of the surface-enhanced Raman substrate with a titanium dioxide nanofilm grown on an aluminum base provided by the application.
[0023] Figure 2 A field emission scanning electron microscope (FE-SEM) picture of the titanium dioxide film of Example 1.
[0024] Figure 3 A SERS spectrum of Example 2.
[0025] Figure 4 A SERS spectrum of Example 3.
[0026] Figure 5 A SERS spectrum of Example 4.
[0027] Figure 6 A SERS spectrum of the substrate prepared in Example 1 and Comparative Example 1 after being soaked in MBA molecules. DETAILED DESCRIPTION
[0028] The application provides a surface-enhanced Raman substrate with a titanium dioxide nanofilm grown on an aluminum base, comprising an aluminum base, an aluminum oxide film on the surface of the aluminum base, and a titanium dioxide nanofilm on the surface of the aluminum oxide film.
[0029] Figure 1 A structure diagram of the surface-enhanced Raman substrate with a titanium dioxide nanofilm grown on an aluminum base provided by the application.
[0030] In the present application, the aluminum substrate preferably comprises an aluminum sheet or a single-layer aluminum film. In the present application, when the aluminum substrate is a single-layer aluminum film, the single-layer aluminum film is preferably deposited on the surface of a material such as glass, a silicon wafer or a textile fabric by a direct current magnetron sputtering method.
[0031] In the present application, the thickness of the aluminum oxide film is preferably 35-60 nm, and more preferably 40 nm; and the thickness of the titanium dioxide nanofilm is preferably 600-900 nm, and more preferably 700 nm.
[0032] The present application also provides a preparation method of the surface-enhanced Raman substrate, comprising the following steps:
[0033] oxidizing the aluminum substrate to obtain an aluminum substrate with an aluminum oxide film formed on the surface thereof;
[0034] mixing a tetrabutyl titanate anhydrous ethanol solution and a nitric acid ethanol solution to obtain a sol by hydrolysis;
[0035] immersing the aluminum substrate with the aluminum oxide film formed on the surface thereof in the sol, growing titanium dioxide on the surface of the aluminum oxide film in situ, and calcining to obtain the surface-enhanced Raman substrate.
[0036] The present application oxidizes the aluminum substrate to obtain an aluminum substrate with an aluminum oxide film formed on the surface thereof.
[0037] In the present application, the oxidation is preferably natural oxidation, and the natural oxidation is preferably oxidation of the aluminum substrate in air at room temperature for more than 24 hours, and more preferably for 48 hours.
[0038] The present application mixes a tetrabutyl titanate anhydrous ethanol solution and a nitric acid ethanol solution to obtain a sol by hydrolysis.
[0039] In the present application, the tetrabutyl titanate anhydrous ethanol solution comprises tetrabutyl titanate and anhydrous ethanol. In the present application, the volume ratio of the tetrabutyl titanate to the anhydrous ethanol is 1-7:5, and more preferably 2-5:5.
[0040] In the present application, the preparation of the nitric acid ethanol solution is as follows:
[0041] mixing deionized water, concentrated nitric acid and anhydrous ethanol to obtain a nitric acid ethanol solution;
[0042] In the present application, the volume ratio of the deionized water, the concentrated nitric acid and the anhydrous ethanol is preferably 5:1:20.
[0043] In the present application, the mixing of the tetrabutyl titanate anhydrous ethanol solution and the nitric acid ethanol solution is preferably dropwise addition of the tetrabutyl titanate anhydrous ethanol solution to the nitric acid ethanol solution with stirring.
[0044] In the present application, the rate of the dropwise adding is preferably 1 drop per 1 second.
[0045] In the present application, the rotating speed of the stirring is preferably 300-520 rpm, more preferably 430 rpm, and the time is preferably 0.5-10 h, more preferably 1-9 h.
[0046] In the present application, during the stirring, the tetrabutyl titanate is hydrolyzed to form tetrabutyl hydrogen titanate.
[0047] In the present application, the aluminum substrate with the surface generated alumina film is placed in the sol, and after the in-situ growth of titanium dioxide on the surface of the alumina film, calcination is performed to obtain the surface-enhanced Raman substrate.
[0048] In the present application, the temperature for the in-situ growth of titanium dioxide is preferably 140-180℃, more preferably 150-160℃, and the holding time is preferably 4-8 h, more preferably 5-7 h.
[0049] In the present application, the in-situ growth of titanium dioxide is preferably performed in a high-pressure kettle lined with polytetrafluoroethylene.
[0050] In the present application, the in-situ growth of titanium dioxide is the process of the decomposition of tetrabutyl hydrogen titanate to form titanium dioxide.
[0051] In the present application, after the in-situ growth of titanium dioxide, the aluminum substrate with the grown titanium dioxide film is preferably cooled to room temperature, and then the surface of the aluminum substrate is rinsed with ultrapure water.
[0052] In the present application, the temperature for the calcination is preferably 400-600℃, more preferably 450℃, and the holding time is preferably 1-4 h, more preferably 2-3 h.
[0053] In the present application, after the calcination, the aluminum substrate is preferably cooled to room temperature. In the present application, the titanium dioxide film after the high-temperature calcination treatment has a higher crystallinity.
[0054] The present application also provides the use of the above-mentioned surface-enhanced Raman substrate in surface-enhanced Raman scattering.
[0055] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.
[0056] Example 1
[0057] The metal aluminum substrate is cut into 5x5 mm 2 , first washed with detergent to remove surface stains, then sequentially ultrasonically cleaned in ultrapure water, ethanol, and ultrapure water for 5 minutes, and then placed in air for natural oxidation for 48 h before use.
[0058] Stir 3 mL of tetrabutyl titanate and 5 mL of anhydrous ethanol to form solution A, and stir 5 mL of deionized water and 1 mL of concentrated nitric acid (mass concentration of 70%) in 20 mL of anhydrous ethanol to form solution B. Add solution A dropwise to solution B at a rate of 1 drop per 1 second. Subsequently, continuously stir for 2 hours, and tetrabutyl titanate is hydrolyzed to obtain a light yellow transparent sol.
[0059] Transfer the prepared sol and the naturally oxidized aluminum substrate into a 50 mL high-pressure kettle lined with polytetrafluoroethylene, and store at 160°C for 6 hours, and then cool to room temperature. Remove the aluminum substrate, and rinse the surface with ultrapure water. Place the aluminum substrate loaded with the titanium dioxide film in a muffle furnace, and maintain at 450°C for 2 hours, and then naturally cool to room temperature.
[0060] Measure the surface morphology of the substrate using a Regulus 8100 scanning electron microscope (SEM) at a voltage of 3.0 kV.
[0061] Figure 2 The field emission scanning electron microscope (FE-SEM) electron image of the titanium dioxide film. It can be seen that a titanium dioxide film composed of nanoparticles is prepared, and the whole is dense and flat.
[0062] Example 2
[0063] Cut the aluminum substrate into a size of 5 x 5 mm 2 , first clean the surface stains using dishwashing liquid, and then sequentially ultrasonically clean in ultrapure water, ethanol, and ultrapure water for 5 minutes. Dry the aluminum substrate with nitrogen, and then place in air for natural oxidation for 48 h.
[0064] Stir 3 mL of tetrabutyl titanate and 5 mL of anhydrous ethanol to form solution A, and stir 5 mL of deionized water and 1 mL of 70% nitric acid in 20 mL of anhydrous ethanol to form solution B. Add solution A dropwise to solution B at a rate of 1 drop per 1 second. Subsequently, continuously stir for 2 hours, and tetrabutyl titanate is hydrolyzed to obtain a light yellow transparent sol.
[0065] Transfer the prepared sol and the naturally oxidized aluminum substrate into a 50 mL high-pressure kettle lined with polytetrafluoroethylene, and store at 160°C for 6 hours, and then cool to room temperature. Remove the aluminum substrate, and rinse the surface with ultrapure water. Place the aluminum substrate loaded with the titanium dioxide film in a muffle furnace, and maintain at 450°C for 2 hours, and then naturally cool to room temperature.
[0066] Use 1 x 10 -3 mol / L of mercaptobenzoic acid (MBA) molecules to characterize the SERS performance of the substrate, and the immersion time of the substrate in the solution is 6 hours.
[0067] Figure 3 The SERS spectra of the substrate before and after soaking with MBA molecules show that the substrate has good surface-enhanced Raman effect.
[0068] Example 3
[0069] The metal aluminum substrate was cut into 5x5mm 2 , and the surface stains were first cleaned using dishwashing liquid, and then sequentially ultrasonic cleaned in ultrapure water, ethanol, and ultrapure water for 5 minutes. The aluminum substrate was dried with nitrogen and then placed in air for natural oxidation for 48 hours.
[0070] 3 mL of tetrabutyl titanate was stirred uniformly with 5 mL of anhydrous ethanol to form solution A, and 5 mL of deionized water and 1 mL of 70% nitric acid were stirred uniformly in 20 mL of anhydrous ethanol to form solution B. Solution A was added dropwise to solution B at a rate of 1 drop per second. Subsequently, stirring was continued for 2 hours, and tetrabutyl titanate was hydrolyzed to obtain a light yellow transparent sol.
[0071] The prepared sol and the naturally oxidized aluminum substrate were transferred to a 50 mL high-pressure kettle lined with polytetrafluoroethylene, and stored at 160°C for 6 hours, and then cooled to room temperature. The aluminum substrate was removed and the surface was rinsed with ultrapure water. The aluminum substrate loaded with the titanium dioxide nanofilm was placed in a muffle furnace, and kept at 450°C for 2 hours, and then naturally cooled to room temperature.
[0072] Different batches (I, II, and III) of titanium dioxide nanofilm substrates were synthesized according to the above steps, and the SERS signal reproducibility of the substrates was characterized using 1x10 - 3 The SERS signal reproducibility of the substrates was characterized using 1x10
[0073] Figure 4 The SERS spectra of 11 randomly selected points on each of the three randomly selected substrates of different batches were determined, and the results show that the substrates have good SERS signal reproducibility (RSD = 5.90%). This is because the dense aluminum oxide film naturally formed on the surface of the titanium dioxide nanofilm interacts with the metal aluminum substrate, and the defect state distribution is uniform, which is conducive to the charge transfer between the titanium dioxide and the adsorbed molecules and the enhancement of the surface-enhanced Raman scattering signal, thereby obtaining high reproducibility of the Raman signal.
[0074] Example 4
[0075] The metal aluminum substrate was cut into 5x5mm 2 , and the surface stains were first cleaned using dishwashing liquid, and then sequentially ultrasonic cleaned in ultrapure water, ethanol, and ultrapure water for 5 minutes. The aluminum substrate was dried with nitrogen and then placed in air for natural oxidation for 48 hours.
[0076] A solution A was prepared by stirring 3 mL of tetrabutyl titanate in 5 mL of anhydrous ethanol to form a solution, and a solution B was prepared by stirring 5 mL of deionized water and 1 mL of 70% nitric acid in 20 mL of anhydrous ethanol. The solution A was added dropwise to the solution B at a rate of 1 drop per 1 second. Subsequently, the tetrabutyl titanate was hydrolyzed by continuous stirring for 2 hours to obtain a light yellow transparent sol.
[0077] The prepared sol and the naturally oxidized aluminum substrate were transferred into a 50 mL high-pressure vessel lined with polytetrafluoroethylene, and stored at 160°C for 6 hours, and then cooled to room temperature. The aluminum substrate was removed and the surface was rinsed with ultrapure water. The titanium dioxide nano-film loaded aluminum substrate was placed in a muffle furnace and kept at 450°C for 2 hours, and then naturally cooled to room temperature.
[0078] The same batch of titanium dioxide nano-film substrate synthesized according to the above steps was placed at room temperature for different time (0 weeks, 1 week, 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, 20 weeks, 24 weeks, 28 weeks), and then the SERS effect of the substrate was characterized by using 1 x 10 -3 mol / L of MBA molecules, and the substrate was immersed in the solution for 6 hours.
[0079] Figure 5 The SERS spectra of the substrate immersed in MBA were taken after the substrate of the same batch was placed for different time, and it can be seen that the substrate still has good SERS effect after being placed for 28 weeks. This is because the dense aluminum oxide film naturally formed on the surface of the aluminum substrate interacts with the titanium dioxide nano-film, effectively preventing the aggregation of titanium dioxide nanoparticles and the change of the titanium dioxide surface defect state, significantly enhancing the stability of the substrate, and extending the storage time of the substrate to more than 20 weeks.
[0080] Comparative Example 1
[0081] A monolayer silver film was prepared on the surface of the hydroxylated glass by electrostatic adsorption.
[0082] The silver oxide film and the titanium dioxide nano-film were sequentially prepared on the surface of the silver film according to the procedure of Example 1.
[0083] Although the above examples have made a detailed description of the present application, it is only a part of the examples of the present application, not all the examples, and other examples can be obtained according to the present examples without creativity, which belong to the protection scope of the present application.
[0084] The SERS performance of the substrate was characterized by using 1 x 10 -3 mol / L of MBA molecules, and the substrate was immersed in the solution for 6 hours.
[0085] Figure 6The SERS spectra of the substrate prepared in Example 1 and Comparative Example 1 after the substrate was soaked with the MBA molecules, from Figure 6 It can be seen that the surface-enhanced Raman effect of the substrate prepared in Example 1 is stronger.
Claims
1. A surface enhanced Raman substrate for growing a nanometer thin film of titanium dioxide on an aluminum base material, characterized by, The surface enhanced Raman substrate comprises an aluminum base, an aluminum oxide film on the surface of the aluminum base, and a titanium dioxide nanofilm on the surface of the aluminum oxide film. The preparation method of the surface enhanced Raman substrate comprises the following steps: oxidizing the aluminum base to obtain an aluminum base with an aluminum oxide film formed on the surface thereof; mixing a tetrabutyl titanate anhydrous ethanol solution and a nitric acid ethanol solution to obtain a sol by hydrolysis; placing the aluminum base with the aluminum oxide film formed on the surface thereof in the sol, growing titanium dioxide in situ on the surface of the aluminum oxide film, and calcining to obtain the surface enhanced Raman substrate. The oxidation is natural oxidation, and the natural oxidation is oxidation of the aluminum base in air at room temperature for more than 24 hours.
2. The surface enhanced Raman substrate of claim 1, wherein, The thickness of the aluminum oxide film is 35-60 nm.
3. The surface enhanced Raman substrate of claim 1 or 2, wherein, The thickness of the titanium dioxide nanofilm is 600-900 nm.
4. The method of producing a surface-enhanced Raman substrate according to any one of claims 1 to 3, characterized in that, The preparation method of the surface enhanced Raman substrate comprises the following steps: oxidizing the aluminum base to obtain an aluminum base with an aluminum oxide film formed on the surface thereof; mixing a tetrabutyl titanate anhydrous ethanol solution and a nitric acid ethanol solution to obtain a sol by hydrolysis; placing the aluminum base with the aluminum oxide film formed on the surface thereof in the sol, growing titanium dioxide in situ on the surface of the aluminum oxide film, and calcining to obtain the surface enhanced Raman substrate. The oxidation is natural oxidation, and the natural oxidation is oxidation of the aluminum base in air at room temperature for more than 24 hours.
5. The production method according to claim 4, wherein The tetrabutyl titanate anhydrous ethanol solution comprises tetrabutyl titanate and anhydrous ethanol, and the volume ratio of the tetrabutyl titanate to the anhydrous ethanol is 1-7:
5.
6. The production method according to claim 4, wherein The preparation of the nitric acid ethanol solution is mixing deionized water, concentrated nitric acid and anhydrous ethanol to obtain the nitric acid ethanol solution.
7. The production method according to claim 4, wherein The temperature for growing the titanium dioxide in situ is 140-180 ℃, and the holding time is 4-8 h.
8. The production method according to claim 4, wherein The calcining temperature is 400-600 ℃, and the holding time is 1-4 h.
9. The surface enhanced Raman substrate of any one of claims 1-3 or the surface enhanced Raman substrate prepared by the preparation method of any one of claims 4-8 is applied in surface enhanced Raman scattering.