Preparation and surface enhanced Raman spectroscopy application of single-layer NIPS3 two-dimensional crystal material
The scalable production of single-layer NIPS3 2D crystal materials addresses the limitations of traditional SERS substrates by providing a cost-effective, stable, and highly sensitive SERS substrate for enhanced Raman signal detection, overcoming the inefficiencies and cost issues of noble metal-based methods and other 2D material preparation techniques.
Patent Information
- Application Number
- CN202411834023.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-21
AI Technical Summary
Current methods for preparing SERS substrates using noble metal nanomaterials are limited by high costs, non-uniformity, and instability, which hinder the widespread application of SERS in fields like chemical sensing and biomedical detection, and existing methods for half-metallic 2D materials are inefficient and difficult to scale up for large-scale production.
A method for preparing single-layer NIPS3 2D crystal materials involves synthesizing NIPS3 bulk crystals from sulfur, red phosphorus, and nickel powder, followed by electrochemical exfoliation and dispersion in organic solvents, resulting in a stable and cost-effective SERS substrate with high production efficiency.
The NIPS3 thin films exhibit high sensitivity, stability, and uniformity, enabling efficient SERS signal enhancement with low-cost, scalable production, outperforming traditional noble metal substrates and other 2D materials like MoS2 and h-BN, and facilitating their application in sensors and medical detection.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of semi-metallic two-dimensional crystal nanomaterials, and more specifically, relates to the preparation and surface enhanced Raman spectroscopy application of a single-layer NIPS3 two-dimensional crystal material. Background Art
[0002] Raman spectroscopy is a molecular vibration spectrum based on inelastic light scattering signals, which can effectively detect molecular structures. The vibration information provided by Raman spectroscopy can be regarded as a biological fingerprint and used to identify a variety of target molecules. Therefore, it has been widely used in biotechnology, medicine, physics and chemistry. However, Raman signals may be significantly interfered in some cases. For example, when there are strong fluorescent molecules in the sample, these fluorescent signals may mask the Raman signals. In order to avoid these interferences and achieve detection at the single molecule level, surface enhanced Raman spectroscopy (SERS) technology has attracted much attention. In 1974, Fleischmann et al. first reported the SERS effect, when researchers detected enhanced Raman signals when nitrogen benzene molecules were adsorbed on a silver film substrate. In SERS testing, the material used to prepare the SERS substrate and its surface morphology are key factors affecting the enhancement factor. The enhancement mechanism of the SERS effect mainly includes two aspects: one is the electromagnetic enhancement mechanism caused by the localized surface plasmon on the rough metal surface, and the other is the chemical enhancement mechanism caused by exciton vibration coupling and charge transfer resonance. Precious metal materials such as gold, silver, copper and platinum all have localized surface plasmon enhancement effects excited by incident light on their surfaces. In addition, nanomaterials prepared from precious metals can further couple the enhanced field of localized surface plasmons to achieve extremely high SERS electromagnetic enhancement factors (about 10 9 Up to 10 10 ). However, SERS substrates made of precious metal nanomaterials also have some disadvantages, such as expensive raw materials, poor substrate uniformity and insufficient stability. Therefore, the development of SERS substrates with simple synthesis, low cost and stable performance has important application value.
[0003] Surface enhanced Raman spectroscopy (SERS) is an extremely sensitive surface analysis method widely used in chemical sensing, biological detection and environmental monitoring. In this field, the design of SERS substrates is crucial to obtain high-quality signals. Semi-metallic two-dimensional materials with zero band gap are ideal candidates for SERS substrates due to their high density of states (DOS) close to the Fermi level, atomically flat surfaces and strong interactions with analytes. At the same time, transition metal sulfide (TMDCs) two-dimensional crystalline materials have attracted widespread attention due to their high specific surface area, high adsorption capacity, good semiconductor properties and single-layer atomic structure that provides more active sites. The nanostructures of these materials not only show localized surface plasmon enhancement effects, but also form strong dipole interactions when the probe molecules are adsorbed, thereby significantly enhancing the Raman signal. However, current preparation methods such as mechanical exfoliation and chemical vapor deposition often have problems of low efficiency or extremely high equipment requirements, which are difficult to meet the needs of large-scale production of surface enhanced Raman spectroscopy (SERS) materials. This limitation restricts the widespread application of semi-metallic two-dimensional materials in the field of SERS. Therefore, it is urgent to develop a convenient and large-scale production method for semi-metallic two-dimensional materials. This method should not only have high production efficiency, but also reduce equipment requirements to promote the research on the SERS properties of semi-metallic two-dimensional materials and provide support for their practical applications. By achieving large-scale production, it can accelerate the progress of related research and expand its application prospects in fields such as sensors, medical testing and environmental monitoring. Summary of the invention
[0004] In order to obtain a two-dimensional material with low manufacturing cost and excellent SERS signal, the present invention provides a preparation method of a single-layer NIPS3 two-dimensional crystal material and a surface enhanced Raman spectroscopy application method.
[0005] In the first aspect, the present invention provides the preparation of a single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy, using the following technical solutions:
[0006] The preparation of single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy include the following steps: S1. Preparation of NIPS3 single crystals: Use sulfur, red phosphorus and nickel powder as raw materials to synthesize NIPS3 bulk crystals. S2. Exfoliation of NIPS3 nanosheets and preparation of dispersion: Tetrabutylammonium fluoroborate was added as an intercalation agent to the propylene carbonate solution, and a NIPS3 single crystal was used as a cathode and a platinum wire was used as a counter electrode and a reference electrode for an electric reaction. The powder collected at the cathode was ultrasonically dispersed, and the unexfoliated large particles were removed by centrifugation. S3. Preparation of surface enhanced Raman scattering substrate: dilute the NIPS3 dispersion into the solution medium, remove the agglomerated nanosheets, filter the NIPS3 solution medium dispersion onto the substrate surface, and dry to obtain the surface enhanced Raman scattering substrate.
[0007] S1. Preparation of NIPS3 single crystals: Use sulfur, red phosphorus and nickel powder as raw materials to synthesize NIPS3 bulk crystals; S2. Exfoliation of NIPS3 nanosheets and preparation of dispersion: Tetrabutylammonium fluoroborate is added as an intercalant in propylene carbonate solution, electrolysis is performed using NIPS3 as the cathode and platinum wire as the counter electrode and reference electrode, the powder collected at the cathode is dispersed by ultrasound, and the unexfoliated large particles are removed by centrifugation:
[0008] By adopting the above technical solution and fully sintering, the purity and yield of NIPS3 single crystals are guaranteed.
[0009] Preferably, the container used for packaging is a quartz tube.
[0010] Preferably, in S1, a low pressure hot sintering method is used to package the powder in a vacuum of 10^ -3 Pa protective gas atmosphere.
[0011] The adoption of the above technical solution is beneficial to improving the sintering efficiency and ensuring the output rate of NIPS3 single crystals.
[0012] Preferably, in S2, the prepared NIPS3 single crystal is used as the cathode material, and platinum wire is used as the counter electrode and the reference electrode. The electrolysis is maintained for 4 hours, and the powder peeled off from the cathode is collected and ultrasonically dispersed in a propylene carbonate solution.
[0013] In a second aspect, the present invention provides an application of a surface enhanced Raman scattering substrate in surface enhanced Raman scattering detection, using the following technical solution:
[0014] An application of a surface enhanced Raman scattering substrate in surface enhanced Raman scattering detection comprises the following steps:
[0015] S1. The Raman probe molecules are configured into solutions of different concentrations in a solution medium, the absorption spectrum data is tested, the ground state energy level and excited state energy level data of the molecules are calculated based on the absorption spectrum data, and a preliminary selection and judgment is made on the wavelength of the Raman laser light source to be used;
[0016] S2. Cut the NIPS3 film and immerse it in the Raman probe molecule solution for 40 minutes, then wash and dry it;
[0017] S3. Place the NIPS3 film adsorbed with Raman probe molecules on the laser confocal Raman microscope platform, select 1-3 wavelengths of laser light sources according to the calculation results of S1, adjust the laser power from 0.1-20mW, test the exposure time from 0.1-3s, integrate 1-50 times, and obtain the surface enhanced Raman scattering signal data with the highest signal-to-noise ratio;
[0018] S4. Test the surface enhanced Raman scattering signals at different positions of the NIPS3 film, evaluate the uniformity of the surface enhanced Raman scattering performance of the NIPS3 film, place the NIPS3 film in the air for 15-45 days, and test the stability of the NIPS3 film after placement.
[0019] By adopting the above technical solution and testing the Raman signal of NIPS3 film under SERS laser light source of different wavelengths, the NIPS3 SERS substrate with high sensitivity, good stability and strong repeatability can be determined, thereby effectively screening the NIPS3 SERS substrate.
[0020] Preferably, the Raman probe molecule is one of a rhodamine 6G molecule, a methylene blue molecule, and an IR780 iodide molecule.
[0021] By adopting the above technical solution, the above three Raman probe molecules are all common Raman probe molecules, which are used to prove that the material has good SERS performance, which is convenient for subsequent testing of other objects to be tested.
[0022] In summary, the present invention has the following beneficial effects:
[0023] 1. Among many two-dimensional materials, the two-dimensional NIPS3 film exhibits excellent high conductivity and is a typical semi-metallic material. Its carrier density at room temperature is much higher than that of other two-dimensional materials. Through the dipole effect between the NIPS3 film and the small molecule to be tested, the small molecule to be tested can be strongly adsorbed, and a molecule-metal coupling system can be constructed. Under the irradiation of laser, the coupling system can undergo photoinduced charge transfer. The occurrence of the PICT process greatly increases the probability of the molecule's transition from the ground state to the excited state, which can significantly increase the SERS signal. Compared with traditional precious metals, NIPS3 thin film raw materials are easy to obtain, cheap, and have better SERS signal uniformity; compared with two-dimensional materials such as graphene, MoS2, and h-BN, the carrier density of NIPS3 thin film is 3-4 orders of magnitude higher, making it an ideal SERS substrate material; compared with mechanical exfoliation and chemical vapor deposition to prepare two-dimensional materials such as MoTe2 and NbSe2, the electrochemical intercalation exfoliation of NIPS3 nanosheets proposed in this scheme has a higher yield and takes less time, making it easy to scale up the SERS activity of two-dimensional semi-metallic materials.
[0024] 2. By testing the Raman signal of NIPS3 film under SERS laser light sources of different wavelengths, the NIPS3 SERS substrate with high sensitivity, good stability and strong repeatability can be determined, thereby effectively screening the NIPS3 SERS substrate.
[0025] 3. The present invention provides a SERS substrate application technology for a large-area, atomic-level-thick NIPS3 film. The film is easy to prepare, highly sensitive, and low in cost. It has an extremely low detection limit and high repeatability for commonly used Raman probe molecules (such as rhodamine 6G molecules), good stability in the air, and is a kind of Raman probe with a concentration as low as 10 -16 Molecular trace detection method of M.
[0026] 4. The present invention does not use precious metals such as gold and silver that are needed in conventional SERS, and does not rely on the construction of fine nanostructures to generate electromagnetic field hotspots. The NIPS3 film prepared by the present invention has high sensitivity, stability, and good reproducibility, and its performance in SERS testing is comparable to that of precious metal nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is an optical microscope morphology of the NIPS3 two-dimensional crystal monolayer obtained in the example;
[0028] Figure 2 XRD patterns of NIPS3 two-dimensional crystals and monolayers obtained in the examples;
[0029] Figure 3 This is a SEM image of the electrochemical exfoliation of the NIPS3 two-dimensional crystal material obtained in the example;
[0030] Figure 4 is a SEM image of a NIPS3 monolayer obtained in the example;
[0031] Figure 5 This is the SERS spectra of the NIPS3 film provided in Application Example 1 when immersed in MB molecules of different concentrations;
[0032] Figure 6 This is the SERS spectra of the NIPS3 film provided in Application Example 2 when immersed in R6G molecules of different concentrations;
[0033] Figure 7 It is the SERS spectra of the NIPS3 film provided in Application Example 3 when immersed in different concentrations of IR780 molecules; DETAILED DESCRIPTION
[0034] The content of the present invention is further described below in conjunction with specific examples, but it should not be construed as limiting the present invention. If not specifically indicated, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.
[0035] Example 1 A NIPS3 crystal, the preparation method of which comprises the following steps: S1. According to mass, weigh 1g of sulfur, 1g of red phosphorus and 3g of nickel powder and package them in 10 -3 Pa in an argon atmosphere, the packaging container was a round quartz tube with an inner diameter of 16 mm, a wall thickness of 2 mm, and a length of 20 cm. It was heated at 700°C and 650°C for 7 days. After naturally cooling to room temperature, the quartz tube was broken and the NIPS3 bulk crystal was taken out. S2. Preparation of NIPS3 nanosheet dispersion: Take NIPS3 two-dimensional single crystal (2 mg) as cathode material, unscrew the platinum wire electrode, place a circular filter paper (10 mm in diameter) as a back support, place the material on the filter paper, put it into the electrode, and then place a circular gold sheet (10 mm in diameter) as a conductive interlayer, tighten the electrode, and add 20 ml of 50 mM tetrabutylammonium fluoroborate in propylene carbonate solution as the electrolyte in the electrolytic cell. S3. Turn on the electrochemical workstation, set the voltage to -5V, and electrolyze for 4h. S4. After the electrolysis is completed, place the dispersion on the filter paper in a 20 ml glass bottle, add propylene carbonate solution, and shake gently to obtain the NIPS3 nanosheet dispersion.
[0036] Calculation of the volume of NIPS3 nanosheet dispersion: Dry the NIPS3 nanosheets by freeze drying, weigh the mass of the obtained nanosheets, calculate the concentration of the NIPS3 nanosheet dispersion, and calculate the volume of the NIPS3 nanosheet dispersion required to prepare a NIPS3 film with a thickness of 2 nm and a diameter of 2.5 cm;
[0037] Preparation of surface enhanced Raman scattering substrate: dilute the NIPS3 nanosheet dispersion into ethanol solution, use anodized aluminum with a pore size of 90nm and a membrane diameter of 2.5cm as a filter membrane, take 5mL of NIPS3 / ethanol dispersion, filter and prepare NIPS3 film, and vacuum dry at 40℃ for 3 hours.
[0038] Application Example 1
[0039] The application of NIPS3 surface enhanced Raman scattering substrate in surface enhanced Raman scattering detection includes the following steps: S1. The Raman probe molecule Rhodamine 6G is configured into 10 -6 , 10-9 , 10 -12 , 10 -15 mol / L ethanol solution, test the absorption spectrum data, calculate the ground state energy level and excited state energy level data of the molecule based on the absorption spectrum data, and make a preliminary selection and judgment on the wavelength of the Raman laser light source to be used; S2. The NIPS3 film prepared in Example 1 was immersed in the Raman probe molecule solution for 40 min, washed with ethanol and dried; S3. Place the NIPS3 film adsorbed with Raman probe molecules on the laser confocal Raman microscope platform. According to the calculation results of S1, select three wavelengths of laser light sources, namely 532nm, 633nm, and 785nm. Adjust the laser power from 0.1-20mW, test exposure time from 0.1-3s, and integration times from 1 to 50 times to obtain the surface enhanced Raman scattering with the highest signal-to-noise ratio.
[0040] Application Example 2
[0041] The application of NIPS3 surface enhanced Raman scattering substrate in surface enhanced Raman scattering detection includes the following steps: S1. The Raman probe molecule methylene blue is configured to 10 -6 , 10 -9 , 10 -12 , 10 -15 , 10 -16 mol / L ethanol solution, test the absorption spectrum data, calculate the ground state energy level and excited state energy level data of the molecule based on the absorption spectrum data, and make a preliminary selection and judgment on the wavelength of the Raman laser light source to be used; S2. The NIPS3 film prepared in Example 1 was immersed in the Raman probe molecule solution for 40 min, washed with ethanol and dried; S3. Place the NIPS3 film adsorbed with Raman probe molecules on the laser confocal Raman microscope platform. According to the calculation results of S1, select three wavelengths of laser light sources, namely 532nm, 633nm, and 785nm. Adjust the laser power from 0.1-20mW, test exposure time from 0.1-3s, and integration times from 1 to 50 times to obtain the surface enhanced Raman scattering with the highest signal-to-noise ratio.
[0042] Application Example 3
[0043] The application of NIPS3 surface enhanced Raman scattering substrate in surface enhanced Raman scattering detection includes the following steps: S1. Configure the Raman probe molecule IR780 into 5x10 -6 , 10 -9 , 10 -10mol / L ethanol solution, test the absorption spectrum data, calculate the ground state energy level and excited state energy level data of the molecule based on the absorption spectrum data, and make a preliminary selection and judgment on the wavelength of the Raman laser light source to be used; S2. The NIPS3 film prepared in Example 1 was immersed in the Raman probe molecule solution for 40 min, washed with ethanol and dried; S3. Place the NIPS3 film adsorbed with Raman probe molecules on the laser confocal Raman microscope platform. According to the calculation results of S1, select three wavelengths of laser light sources, namely 532nm, 633nm, and 785nm. Adjust the laser power from 0.1-20mW, test exposure time from 0.1-3s, and integration times from 1 to 50 times to obtain the surface enhanced Raman scattering with the highest signal-to-noise ratio.
Claims
1. Preparation of single-layer NIPS3 two-dimensional crystal materials and application of surface-enhanced Raman spectroscopy, characterized by: The following steps are involved: S1. Preparation of NIPS3 single product: Use sulfur, red phosphorus and nickel powder as raw materials to synthesize NIPS3 bulk crystals. S2. Exfoliation of NIPS3 nanosheets and preparation of dispersion: Tetrabutylammonium fluoroborate was added as an intercalating agent to the propylene carbonate solution, and electrolysis was performed using NIPS3 alone as the cathode and platinum wire as the counter electrode and reference electrode. The powder collected at the cathode was dispersed by ultrasound, and the unexfoliated large particles were removed by centrifugation. S3. Prepare NIPS3 surface-enhanced Raman scattering substrate: dilute the NIPS3 dispersion into the solution medium, remove the agglomerated nanosheets, filter the NIPS3 solution medium dispersion onto the substrate surface, and dry to obtain the surface-enhanced Raman scattering substrate.
2. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 1, characterized in that: S1. Preparation of NIPS3 single product: Take about 1 part sulfur, 1 part red phosphorus, and 3 parts nickel powder by mass, grind them evenly in a protective gas atmosphere, seal them in a quartz tube, and evacuate to 10^ -3 Pa, filled with argon three times, placed in a double-zone tube furnace, heated at 700 °C and 650 °C for 7 days, and finally cooled naturally to obtain NIPS3 bulk crystals.
3. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 2, characterized in that: The container used for packaging is a quartz tube.
4. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 2, characterized in that: The powder is packaged in a vacuum of 10^ -3 Pa of protective gas atmosphere.
5. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 2, characterized in that: The cathode material clip fixture used was the sample support.
6. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 1, characterized in that: In S2, the prepared NIPS3 single product was used as the cathode material, and the NIPS3 was sandwiched between the sample support, and the platinum wire was used as the counter electrode and the reference electrode. The electrolysis was maintained for 4 hours, and the powder peeled off from the cathode was collected and ultrasonically dispersed in a propylene carbonate solution.
7. The preparation of the single-layer NIPS3 two-dimensional crystal material and the application of surface enhanced Raman spectroscopy according to claim 2, characterized in that: The electrolyte used was 50 mM tetrabutylammonium fluoroborate.
8. A surface enhanced Raman scattering substrate prepared by the preparation method according to any one of claims 1 to 7.
9. An application of a surface enhanced Raman scattering substrate obtained by the preparation method according to any one of claims 1 to 7 in surface enhanced Raman scattering detection, characterized in that: The detection method includes the following steps: S1. The Raman probe molecules are configured into solutions of different concentrations in a solution medium, the absorption spectrum data is tested, the ground state energy level and excited state energy level data of the molecules are calculated based on the absorption spectrum data, and a preliminary selection and judgment is made on the wavelength of the Raman laser light source to be used; S2. Cut the NIPS3 film and soak it in the Raman probe molecule solution for 40 minutes, then soak it in ethanol to clean it and dry it; S3. Place the NIPS3 film adsorbed with Raman probe molecules on the laser confocal Raman microscope platform, select 1-3 wavelengths of laser light sources according to the calculation results of S1, adjust the laser power from 0.1-20mW, test the exposure time to 0.1-3s and the integration times to 1-50 times, and obtain the surface enhanced Raman scattering signal data with the highest signal-to-noise ratio.
10. The use of a surface enhanced Raman scattering substrate according to claim 7 in surface enhanced Raman scattering detection, characterized in that: The Raman probe molecule is one of a rhodamine 6G molecule, a methylene blue molecule, and an IR780 iodide molecule.