V5S4 nanoflower SERS (Surface Enhanced Raman Scattering) substrate with SERS activity as well as preparation method and application thereof

Abstract

The invention relates to a V5S4 nanoflower SERS (Surface Enhanced Raman Scattering) substrate with SERS activity as well as a preparation method and application thereof. The V5S4 nanoflower SERS substrate is formed by the cross growth of V5S4 nanosheets; the exposed crystal face of the V5S4 nanoflower SERS substrate is a (110) face.

Description

Technical Field

[0001] The present invention relates to a V 5 S 4 Nanoflower SERS substrate and preparation method and application thereof, specifically relating to a V-shaped nanoflower with a size of 200-1000nm prepared by a hydrothermal method and formed by cross-growth of nanosheets 5 S 4 The invention discloses a method for a surface enhanced Raman scattering (SERS) substrate of a nano flower, and belongs to the field of laser Raman spectroscopy and detection technology. Background Art

[0002] Surface Enhanced Raman Scattering (SERS) refers to the phenomenon that the Raman signal of molecules adsorbed on the surface of a rough substrate is significantly enhanced. The phenomenon was discovered in 1973 and formally proposed in 1977. As a sensitive vibrational spectroscopy technique, SERS spectroscopy can provide information on the material structure and chemical composition down to the single-molecule level, thereby achieving trace detection of analytes. Compared with traditional atomic absorption spectroscopy, colorimetry, fluorescence, nuclear magnetic resonance, and immunochromatography methods, SERS spectroscopy has the advantages of being fast, sensitive, and non-destructive. Therefore, SERS technology has attracted the interest of many scholars, and a large number of substrate materials and detection methods related to SERS technology have been reported. It has been widely used in environmental pollutant detection, food safety detection, and biosensing, especially in virus detection, tumor identification, and even the current popular field of bioimaging. Due to its specificity and non-destructiveness, it has broad application prospects.

[0003] The core of SERS detection lies in the selection of substrate materials. Traditional SERS substrate materials are mainly precious metal nanoparticles such as Au and Ag. Through the mechanism of electromagnetic enhancement, that is, when the frequency of the incident light is close to the plasma vibration frequency of the metal nanosphere surface, a strong local electric field is formed on the surface of the metal particle, which significantly enhances the Raman signal of the analyzed substance in this area. Precious metals have high carrier concentrations, and their unique plasma resonance effect makes its enhancement factor (EF) reach 10 14 However, precious metal substrates have the disadvantages of high production cost, limited types, poor chemical stability, poor biocompatibility, and poor repeatability due to uneven hot spot distribution. These difficult-to-break-through problems have greatly limited the application of precious metal substrates. On the contrary, semiconductor substrates have the advantages of easy adjustment of band structure, low production cost, good biocompatibility, high spectral stability and good repeatability, which make up for the shortcomings of precious metal substrates. In addition, semiconductor substrates have the selective enhancement of molecules and molecular Raman peaks, which has broad application prospects in the field of biological analysis. Therefore, we need semiconductor materials with high SERS activity.

[0004] The high SERS activity of precious metal nanoparticles such as Au and Ag comes from the surface plasmon effect brought about by their rich carrier concentration, while semiconductor materials do not have sufficient carrier concentration and it is difficult to produce the plasmon resonance effect like precious metals. 10 cm -3 ; The carrier concentration of Au can reach 10 22 cm -3 , which results in the electromagnetic enhancement effect dominated by the plasma effect not being significant. Therefore, the SERS phenomenon of semiconductor materials is explained by chemical enhancement dominated by charge transfer. Charge transfer refers to the interaction between material molecules and other materials adsorbed on the surface of the SERS substrate after the material molecules are adsorbed on the surface of the SERS substrate, thereby affecting the charge density distribution of the material molecules, causing the polarizability of the molecules to change, increasing the Raman scattering cross section of the molecules, and enhancing the Raman signal of the molecules. At present, a large number of SERS-active semiconductor substrate materials have been reported, and transition metal sulfides (TMDS), as a special type of two-dimensional material that has emerged in recent years, have unique optoelectronic properties and high stability, as well as strong in-plane bonds and weak out-of-plane interactions, and have great application potential in SERS detection. The pure phase MoS 2 The SERS detection limit of the microspheres can reach 10 -8 M, and its enhancement factor can reach 5.3×10 5 , through morphology control, MoS 2 The SERS detection limit of the nanocage can reach 10 -10 M; while micron-sized SnS 2 The SERS detection limit of the small ball can reach 10 -13 M, its enhancement factor can reach 3×10 8 Considering that transition metal elements can provide abundant excited state electrons, they are often used to combine with non-metallic elements to form compounds. 2 O 5 , Nb 2 O 5 Semiconductor SERS substrate materials, with detection limits of 9×10 -9 M and 10 -7 M. Summary of the invention

[0005] To this end, the object of the present invention is to provide a V having a special morphology and high SERS activity. 5 S 4 The material, its preparation method and application provide the material basis for the practical application of SERS technology.

[0006] In one aspect, the present invention provides a V 5 S 4 Nanoflower SERS substrate, the V 5 S 4 Nanoflower SERS substrate is made of V 5 S 4 Nanosheets cross-growth composition; the V 5 S 4 The exposed crystal face of the nanoflower SERS substrate is the (110) face.

[0007] Compared with the existing vanadium sulfide synthesis method, relatively uniform nanospheres were obtained by uniformly mixing ammonium metavanadate powder and sodium thiosulfate powder without adding any other surfactant, performing hydrothermal reaction at 180°C for 14h, and then vacuum drying at 80°C; by uniformly mixing ammonium metavanadate powder and sodium thiosulfate powder, adding 10mL of NH 3 ·H 2 O as a surfactant, hydrothermal reaction at 180 ° C for 14h and 16h, and then vacuum drying at 80 ° C to obtain nanorod-shaped vanadium sulfide of different lengths; sodium orthovanadate powder and ammonium thiosulfate powder were evenly mixed, 2mL polyethylene glycol 400 was added as a surfactant, and then vacuum dried at 80 ° C to obtain nanosheets of different thicknesses. The vanadium sulfides of different morphologies synthesized by these methods generally have poor SERS activity.

[0008] In the present invention, V 5 S 4 Nanoflowers are directly synthesized through a simple one-step hydrothermal reaction. Polyvinyl pyrrolidone K30 is added as a surfactant in the reaction. By adjusting the quality of the surfactant and the time of the hydrothermal reaction, V 5 S 4 The nanosheets cross-grow to form nanoflowers of 200-1000nm, which have a large specific surface area and weak out-of-plane interactions, making it easy to form chemical bonds, which is beneficial to the adsorption of molecules and promotes charge transfer between the substrate and the molecules, greatly improving the intensity of the SERS signal. 5 S 4 When nanoflowers are used as SERS substrates, SERS detection of rhodamine 6G (R6G) and methyl violet (MV) molecules is performed. -7 M, there is still a strong signal. The present invention synthesizes a two-dimensional semiconductor material V by a hydrothermal method 5 S 4 The SERS performance of nanoflowers was explored by changing the time of hydrothermal reaction and the mass of added surfactant.

[0009] Preferably, the V5 S 4 The thickness of the nanosheets in the nanoflowers is 2 to 10 nm, and the diameter is 100 to 900 nm.

[0010] Preferably, the V 5 S 4 The size of the nanoflower SERS substrate is 200 to 1000 nm.

[0011] In another aspect, the present invention provides a V 5 S 4 A method for preparing a nanoflower SERS substrate comprises: (1) adding a vanadium source, a surfactant, and a sulfur source into deionized water and mixing them to obtain a precursor solution; (2) placing the obtained precursor solution in a reaction kettle and subjecting it to a hydrothermal reaction to obtain the V 5 S 4 Nanoflower SERS substrate.

[0012] In the present invention, a certain amount of sodium orthovanadate is added to deionized water, followed by the addition of polyvinyl pyrrolidone K30 powder, and stirred evenly to obtain a uniform transparent solution, and thioacetamide powder is dissolved in the above solution, and stirred evenly to obtain a precursor solution. The precursor solution is then placed in a 100 mL reactor, and hydrothermally reacted at 160° C. for 15-24 hours, and then centrifuged, washed, and vacuum dried to obtain the V 5 S 4 Substrate.

[0013] Preferably, in step (1): firstly, a vanadium source is added to deionized water, and then a surfactant is added and mixed to obtain a mixed transparent solution; and then a sulfur source is added and mixed to obtain a precursor solution.

[0014] Preferably, in step (1): the sulfur source is at least one of thioacetamide, sodium thiosulfate and potassium thiosulfate; The vanadium source is at least one of sodium orthovanadate, ammonium metavanadate and potassium orthovanadate; The surfactant includes at least one of polyvinyl pyrrolidone K30, polyethylene glycol 400 and ammonia water.

[0015] Preferably, in step (1): the mixing method is electromagnetic stirring, the speed is 500-600 rpm, and the time is 10-30 minutes; The molar ratio of the sulfur source to the vanadium source is (2-7):1, preferably 5:1.

[0016] Preferably, in step (1), the ratio of the sulfur source to deionized water is 20 mmol: (50-80) mL; The ratio of the vanadium source to deionized water is 4 mmol: (50-80) mL; The ratio of the vanadium source to the surfactant is 4 mmol: (0.25-1.0) g.

[0017] Preferably, in step (2), the temperature of the hydrothermal reaction is 140-180° C.; and the time of the hydrothermal reaction is 15-24 hours.

[0018] Preferably, after the hydrothermal reaction, centrifugation, washing and drying are performed; The centrifugal speed is 9000-11000, and the time is 4-8 minutes; preferably, the centrifugal speed is 10000 rpm, and the time is 5 minutes; The washing solvents are anhydrous ethanol and deionized water, and the washing times are more than 5 times; The drying method is vacuum drying, the vacuum drying temperature is 60-80° C., and the time is 24-48 hours.

[0019] In another aspect, the present invention provides a V 5 S 4 Application of nanoflower SERS substrates in laser Raman spectroscopy and detection.

[0020] Beneficial effects of the present invention: In the present invention, V with high SERS activity is prepared 5 S 4 Nanoflower, its concentration is 10 -7 The probe molecules of rhodamine 6G (R6G) and methyl violet (MV) still have high signals and can be directly used for the detection of various biomacromolecules. 5 S 4 The discovery of nanoflowers shows great potential in practical applications such as biosensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 0.50 g of surfactant polyvinyl pyrrolidone K30 was added and the V 5 S 4 SEM morphology of nanoflowers (scale bars are all 500 nm), where (a) 15h; (b) 20h; (c) 24h; Figure 2 0.50 g of polyvinyl pyrrolidone K30 was added and the reaction was carried out at 160 °C for 15, 20, and 24 hours to obtain V 5 S 4 XRD pattern of nanoflowers; Figure 30.50 g of polyvinyl pyrrolidone K30 was added and the hydrothermal reaction was carried out at 160 ° C for 15, 20, and 24 hours to obtain V 5 S 4 Nano flower pair 10 -7 Raman spectra of different dye molecules of M, including (a) R6G molecule and (b) MV molecule; Figure 4 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur-vanadium ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 XRD pattern of nanoflowers; Figure 5 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 Nanoflower SERS performance test diagram; Figure 6 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 XRD pattern of nanoflowers; Figure 7 For Example 12 and 13, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 Nanoflower SERS performance test diagram. DETAILED DESCRIPTION

[0022] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0023] In the present disclosure, V 5 S 4 Nanoflower SERS substrate is made of V 5 S 4 The nanosheets are formed by cross-growth, the particle size is uniform, and the size of each nanoflower is about 200-1000nm, with high SERS activity.

[0024] In the present invention, V 5 S 4The preparation method of the nanoflower SERS substrate comprises: mixing reactants to form a uniform solution, performing a hydrothermal reaction, and vacuum drying to collect the product. Preferably, the present invention performs the hydrothermal reaction at 160°C, and controls the V 5 S 4 The grain growth process obtains V 5 S 4 Nanoflower substrate.

[0025] The following is an exemplary description of V 5 S 4 Preparation method of nanoflowers.

[0026] A certain amount of purchased commercial sodium orthovanadate is dissolved in deionized water. Specifically, 4 mmol of sodium orthovanadate powder is added to 60 mL of deionized water, and then a certain amount of polyvinyl pyrrolidone K30 is added as a surfactant. As an example, 0.25 g of polyvinyl pyrrolidone K30 is added as a surfactant, and electromagnetic stirring is performed at a temperature of about 40°C to form a uniform mixed solution. In this reaction, sodium orthovanadate is used as a vanadium source.

[0027] Then a certain amount of thioacetamide (TAA) is dissolved in the above solution. As an example, 20 mmol of thioacetamide TAA powder is added to the above solution, and stirring is continued at a temperature of about 40° C. for about 20 minutes (for example, the speed can be 400 to 600 rpm, the time is 10 to 30 minutes, preferably 20 minutes), until a yellow transparent solution is formed to obtain the desired precursor solution. In this reaction, thioacetamide powder TAA is used as a sulfur source.

[0028] The above precursor solution was hydrothermally reacted to prepare V 5 S 4 As an example, the above precursor solution is transferred to a 100 mL reactor and subjected to hydrothermal reaction at 160°C for 15-24 hours to obtain a black solution, which is then centrifuged, washed and vacuum dried to obtain the black V 5 S 4 Nano flower powder. The centrifugal speed can be 10000-12000 rpm, and the time is 5-10 minutes. For example, the centrifugal speed is 10000 rpm, and the time is 10 minutes.

[0029] In the present invention, the inner lining material of the hydrothermal reaction kettle used in the hydrothermal reaction process is polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL).

[0030] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description of this article, and are not limited to the specific values ​​​​exemplified below. In the following examples and comparative examples, unless otherwise specified, the centrifugal speed used is 10000rpm / min, and the time is 10min.

[0031] Embodiment 1: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.25 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 15 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0032] Embodiment 2: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.50 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 15 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0033] Embodiment 3: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 1.00 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 15 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0034] Embodiment 4: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.25 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 20 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. to obtain a black V 5 S 4 Nano flower powder.

[0035] Embodiment 5: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.50 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 20 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4Nano flower powder.

[0036] Embodiment 6: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 1.00 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 20 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0037] Embodiment 7: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.25 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 24 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0038] Embodiment 8: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 0.50 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 24 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0039] Embodiment 9: First, 0.74 g (4 mmol) of sodium orthovanadate powder was added to 60 mL of deionized water, and then 1.00 g of polyvinyl pyrrolidone K30 powder was added, and electromagnetic stirring was performed at about 40° C. for 10-15 minutes to make the powder dissolve quickly to obtain a mixed transparent solution; then, 1.5 g of TAA powder (20 mmol) was added to the above solution, and electromagnetic stirring was continued at 60° C. for 20 minutes to make the powder dissolve quickly to form a yellow transparent uniform solution, and then the above precursor solution was transferred to a 100 mL polytetrafluoroethylene (PTFE) or para-polyphenylene (PPL) lined hydrothermal reactor, and hydrothermally reacted at 160° C. for 24 hours to obtain a black precipitate. Finally, the obtained precipitate was centrifuged, washed with anhydrous ethanol and deionized water for multiple times, and vacuum dried at 80° C. for 24 hours to obtain a black V 5 S 4 Nano flower powder.

[0040] The main difference between Examples 1-3, 4-6, and 7-9 is that the hydrothermal reaction time is extended to allow the reactants to react fully; the main difference between Examples 1, 4, and 7 is that the quality of the surfactant is changed to explore the effect of the quality of the surfactant on the reactants.

[0041] Embodiment 10: The preparation process of the nanoflower powder in this Example 10 is the same as that in Example 2, except that the molar ratio of the sulfur source to the vanadium source is 4:1. That is, 1.5 g (20 mmol) of TAA powder and 0.74 g (5 mmol) of sodium orthovanadate are added.

[0042] Embodiment 11 The preparation process of the nanoflower powder in this Example 11 is similar to that in Example 2, except that the molar ratio of the sulfur source to the vanadium source is 3:1. That is, 1.57 g (21 mmol) of TAA powder and 1.28 g (7 mmol) of sodium orthovanadate are added.

[0043] Example 12 The preparation process of the nanoflower powder in this Example 12 is the same as that in Example 2, except that the molar ratio of the sulfur source to the vanadium source is 6:1. That is, 1.35 g (18 mmol) of TAA powder and 0.55 g (3 mmol) of sodium orthovanadate are added.

[0044] Embodiment 13 The preparation process of the nanoflower powder in this Example 13 is similar to that in Example 2, except that the molar ratio of the sulfur source to the vanadium source is 7:1. That is, 1.57 g (21 mmol) of TAA powder and 0.55 g (3 mmol) of sodium orthovanadate are added.

[0045] Figure 1 V was generated by adding 0.5 g of surfactant polyvinyl pyrrolidone K30 at 160 ° C for different time periods. 5 S 4 Microscopic morphology of nanoflowers, a is for hydrothermal reaction after 15h, b is for hydrothermal reaction after 20h, and c is for hydrothermal reaction after 24h.

[0046] Figure 2 V prepared in Examples 4, 5 and 6 by adding the same mass of surfactant polyvinyl pyrrolidone K30 at 160°C and adjusting the hydrothermal reaction time 5 S 4 The microscopic morphology of nanoflowers. Under the same mass of surfactant, as the hydrothermal reaction is prolonged, it can be seen that V 5 S 4 The characteristic peak shifts toward the large angle direction.

[0047] Figure 3 In order to test the SERS performance of hydrothermal reaction at 160℃ for 15h, 20h and 24h, 0.50g polyvinyl pyrrolidone K30 surfactant was added. R6G and MV were used as markers. The results showed that when the concentration of probe molecules was as low as 10 -7 M, there is still a high SERS intensity. When the hydrothermal reaction time is 15h, the SERS intensity reaches a peak. With the extension of the reaction time, the SERS intensity of the probe molecule gradually decreases.

[0048] Figure 4 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur-vanadium ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V5 S 4 XRD diagram of nanoflowers. The results show that as the sulfur-vanadium ratio decreases, although V 5 S 4 The corresponding crystal plane peak position has basically no displacement, but its intensity is significantly reduced.

[0049] Figure 5 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 Nanoflower SERS performance test diagram, using R6G and MV probe molecules as markers. The results show that when the probe molecule concentration is as low as 10 -7 M, there is still obvious SERS activity. However, as the sulfur-vanadium ratio decreases, the SERS activity decreases significantly. When the sulfur-vanadium ratio is 5:1, the SERS activity is the highest. This is consistent with the peak intensity corresponding to XRD.

[0050] Figure 6 For Example 10 and 11, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 XRD diagram of nanoflowers. The results show that with the increase of sulfur-vanadium ratio, although V 5 S 4 The corresponding crystal plane peak position has basically not shifted, but its intensity is significantly reduced. Moreover, when the sulfur-vanadium ratio reaches 7:1, obvious amorphization phenomenon occurs.

[0051] Figure 7 For Example 12 and 13, 0.5 g of surfactant polyvinyl pyrrolidone K30 was added, and different sulfur and vanadium source ratios were adjusted, and then a hydrothermal reaction was carried out at 160° C. for 15 h to obtain V 5 S 4 Nanoflower SERS performance test diagram, using R6G and MV probe molecules as markers. The results show that when the probe molecule concentration is as low as 10 -7 M, there is still obvious SERS activity. However, with the increase of sulfur-vanadium ratio, SERS activity decreases significantly. When the sulfur-vanadium ratio is 5:1, SERS activity is the highest. When the sulfur-vanadium ratio is 7:1, SERS signal is very weak. Figure 5 and Figure 7 , the SERS signal from strong to weak is: 5:1>6:1>4:1>7:1>3:1. This shows that amorphization leads to a decrease in performance. This is consistent with the intensity corresponding to XRD.

Claims

1. A V 5 S 4 Nanoflower SERS substrate, It is characterized in that The V 5 S 4 Nanoflower SERS substrate is made of V 5 S 4 Nanosheets cross-growth composition; the V 5 S 4 The exposed crystal face of the nanoflower SERS substrate is the (110) face.

2. V according to claim 1 5 S 4 Nanoflower SERS substrate, It is characterized in that The V 5 S 4 The thickness of the nanosheets in the nanoflowers is 2 to 10 nm, and the diameter is 100 to 900 nm.

3. V according to claim 2 5 S 4 Nanoflower SERS substrate, It is characterized in that The V 5 S 4 The size of the nanoflower SERS substrate is 200 to 1000 nm.

4. A V according to any one of claims 1 to 3 5 S 4 Preparation method of nanoflower SERS substrate, It is characterized in that include: (1) adding a vanadium source, a surfactant, and a sulfur source into deionized water and mixing them to obtain a precursor solution; (2) placing the obtained precursor solution in a reaction kettle and subjecting it to a hydrothermal reaction to obtain the V 5 S 4 Nanoflower SERS substrate.

5. The preparation method according to claim 4, It is characterized in that In step (1): firstly, a vanadium source is added to deionized water, and then a surfactant is added and mixed to obtain a mixed transparent solution; then a sulfur source is added and mixed to obtain a precursor solution.

6. The preparation method according to claim 4 or 5, It is characterized in that In step (1): the sulfur source is at least one of thioacetamide, sodium thiosulfate and potassium thiosulfate; The vanadium source is at least one of sodium orthovanadate, ammonium metavanadate and potassium orthovanadate; The surfactant includes at least one of polyvinyl pyrrolidone K30, polyethylene glycol 400 and ammonia water.

7. The preparation method according to any one of claims 4 to 6, It is characterized in that In step (1), the mixing method is electromagnetic stirring, the speed is 500 to 600 rpm, and the time is 10 to 30 minutes; The molar ratio of the sulfur source to the vanadium source is (2-7):1, preferably 5:

1.

8. The preparation method according to any one of claims 4 to 7, It is characterized in that In step (1), the ratio of the sulfur source to deionized water is 20 mmol: (50-80) mL; The ratio of the vanadium source to deionized water is 4 mmol: (50-80) mL; The ratio of the vanadium source to the surfactant is 4 mmol: (0.25-1.0) g.

9. The preparation method according to any one of claims 4 to 8, It is characterized in that In step (2), the temperature of the hydrothermal reaction is 140 to 180° C.; the time of the hydrothermal reaction is 15 to 24 hours.

10. The preparation method according to any one of claims 4 to 9, It is characterized in that After the hydrothermal reaction, it is centrifuged, washed and dried; The centrifugal speed is 9000-11000, and the time is 4-8 minutes; preferably, the centrifugal speed is 10000 rpm, and the time is 5 minutes; The washing solvents are anhydrous ethanol and deionized water, and the washing times are more than 5 times; The drying method is vacuum drying, the vacuum drying temperature is 60-80° C., and the time is 24-48 hours.

11. A V according to any one of claims 1 to 3 5 S 4 Application of nanoflower SERS substrates in laser Raman spectroscopy and detection.

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