CN110927140A - Method for rapidly preparing nano Ag film surface enhanced Raman substrate through liquid-liquid interface - Google Patents
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Abstract
The invention discloses a method for rapidly preparing a nano Ag film surface enhanced Raman substrate by a liquid-liquid interface, which takes AgNO3The aqueous solution and aqueous PVA solution were added to ice-cold NaBH4In aqueous solution, vigorously stirred, and the mixture then boiled to decompose excess NaBH4Stopping heating, stirring and cooling to room temperature to obtain the Ag nano sol. And carrying out vortex mixing on the Ag nano sol, the phase transfer catalyst and the nonpolar organic solvent, then standing to form a clear water-oil phase, and removing the oil phase to obtain the Ag nano film, namely the nano Ag film surface enhanced Raman substrate. The invention adopts nonpolar organic solvent as oil phase, hydrophobic cation with opposite charge to Ag nano particle as phase transfer catalyst, and prepares densely arranged Ag nano film rapidly after simple vortex. Compared with the traditional sol method, the Ag nano film obtained by the method has better consistency and repeatability.
Description
Technical Field
The invention relates to a method for rapidly preparing a nano Ag film surface enhanced Raman substrate by a liquid-liquid interface.
Background
Surface-enhanced Raman spectroscopy (SERS) has received wide attention for its fingerprint identification characteristics, high sensitivity, fast detection, convenient operation, and non-destructive detection. Given that plasmon resonance enhancement in the "hot spot" region plays a key role in the sensitivity of SERS detection, much research effort in SERS has focused on the controlled and reproducible fabrication of metal nanostructures. Compared to conventional noble metal sols, it has been found that self-assembly of metal nanoparticles at the liquid-liquid interface exhibits better SERS enhancement. Wherein the colloid of metal nanoparticles (Au, Ag) is used as water phase; cyclohexane, toluene, chloroform, heptane, etc. may be used as the oil phase. At present, the Au nano single-layer film is developed into a mature metal single-layer film substrate, firstly, people need to add inducers such as ethanol and the like to enable Au nano particles to be self-assembled at a water-oil interface, and then, the Au nano particles are self-assembled at a liquid-liquid interface by simple vortex. Although the prepared Au nano monolayer film is compact, uniform and stable, the SERS signal enhancement effect is not ideal enough in trace analysis. Compared with Au, Ag has higher SERS enhancement activity, so the development of Ag nano single-layer films still has important significance. However, there is a need to prepare effective SERS-active substrates with some materials, such as a combination of thiolated poly (ethylene glycol) and hydrophobic capping agent (e.g., dodecyl mercaptan) to optimize Ag nanoparticles, or different amino acids as morphology modulators, so that self-assembled Ag monolayer films at the interface become effective SERS-active substrates. Compared with an Au nano single-layer film, Ag film liquid-liquid two-phase film forming reports are few, and the Ag nano film is difficult to form due to complex and unstable properties of Ag, so that how to prepare an SERS substrate with good and stable enhancement performance still remains a problem to be further explored.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention aims to provide a method for rapidly preparing a surface enhanced Raman substrate of a nano Ag film by a liquid-liquid interface.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film by the liquid-liquid interface is characterized by comprising the following steps of:
1) taking AgNO3Mixing the aqueous solution and the PVA aqueous solution for 3-10 min by ultrasonic treatment, and adding the obtained mixed solution into ice-cold NaBH in two to four batches on average4In the aqueous solution, the color of the solution was observed to change from colorless to colorless under vigorous stirringI.e. turns brown yellow, and then the mixture is boiled for 0.5-1.5 h to decompose the excess NaBH4Stopping heating, stirring and cooling to room temperature to obtain Ag nano sol, and refrigerating for later use;
2) placing the Ag nano sol obtained in the step 1) in a centrifugal tube, adding a phase transfer catalyst and a nonpolar organic solvent, transferring the centrifugal tube into a vortex mixer, carrying out vortex mixing, forming an emulsion in the centrifugal tube, standing, separating the emulsion into clear water and oil phases, forming a Ag nano film with metallic luster at a water-oil interface, removing an oil phase, and obtaining the Ag nano film on the surface of a water phase, namely the nano Ag film surface enhanced Raman substrate. The oil phase can be removed in the step 2) by adopting the following modes: when a nonpolar organic solvent with density higher than that of water, such as dichloromethane or trichloromethane, is used as an oil phase, a fine needle cylinder is used for extracting to remove a lower oil phase; when a nonpolar organic solvent with density smaller than that of water, such as benzene, toluene, cyclohexane or n-hexane, is used as the oil phase, the centrifuge tube is inverted and the upper oil phase is removed by opening.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film by the liquid-liquid interface is characterized in that in the step 1), the mass fraction of the PVA aqueous solution is 0.08-0.12%; AgNO3The mass fraction of the aqueous solution is 0.06-0.10%, and NaBH4The mass fraction of the aqueous solution is 0.006-0.010%, and NaBH4Aqueous solution, AgNO3The volume ratio of the aqueous solution to the PVA aqueous solution is 8-12: 1-3: 1.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film by the liquid-liquid interface is characterized in that the mass fraction of the PVA aqueous solution is 0.1 percent; AgNO3The mass fraction of the aqueous solution is 0.08 percent, and the NaBH is added4The mass fraction of the aqueous solution is 0.008 percent, and NaBH is added4Aqueous solution, AgNO3The volume ratio of the aqueous solution to the aqueous PVA solution was 10: 2: 1.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film through the liquid-liquid interface is characterized in that in the step 2), the nonpolar organic solvent is dichloromethane, trichloromethane, benzene, toluene, cyclohexane or n-hexane, and preferably n-hexane.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film through the liquid-liquid interface is characterized in that in the step 2), the phase transfer catalyst is cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide or tetrabutyl ammonium bromide, and preferably the cetyl trimethyl ammonium bromide.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film through the liquid-liquid interface is characterized in that in the step 2), the volume ratio of the Ag nano sol to the non-polar organic solvent is 1: 0.25-6, and preferably 1: 1.
The method for rapidly preparing the surface enhanced Raman substrate of the nano Ag film through the liquid-liquid interface is characterized in that in the step 2), the volume ratio of the phase transfer catalyst to the Ag nano sol is 1: 16-23, and preferably 1: 20.
The method for rapidly preparing the nano Ag film surface enhanced Raman substrate through the liquid-liquid interface is characterized in that in the step 2), the rotational speed of vortex mixing of a centrifugal tube in a vortex mixing instrument is 2400-2600 r/min, and the time for vortex mixing is 5-60 s.
The method for rapidly preparing the nano Ag film surface enhanced Raman substrate through the liquid-liquid interface is characterized in that the rotating speed of a centrifugal tube for vortex mixing in a vortex mixer is 2500r/min, and the time for vortex mixing is 40 s.
Compared with the prior art, the invention has the following beneficial effects:
1) the Ag nano single-layer film prepared by the method is compact, uniform and stable, the SERS signal enhancement effect is ideal in trace analysis, the Ag nano particles can be effectively prevented from agglomerating by adding PVA in the preparation process of the Ag nano single-layer film, experiments show that the Ag film forming state and the film forming efficiency are good under the condition that cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide or tetrabutyl ammonium bromide and the like are used as phase transfer catalysts, and the formed Ag nano single-layer film has a good SERS signal enhancement effect.
2) According to the invention, a series of nonpolar organic solvents are used as oil phases, hydrophobic cations with charges opposite to that of Ag nanoparticles are used as phase transfer catalysts, and the Ag nano-films in compact arrangement are quickly prepared after simple vortex. Compared with the traditional sol method, the Ag nano film obtained by the method has better consistency and repeatability.
Drawings
FIG. 1a is a TEM image of Ag nanosol prepared in example 1;
FIG. 1b is a TEM image of the Ag nano-film prepared in example 2;
FIG. 2 is a graph comparing UV absorption curves of Ag nanosol and Ag nanofilm prepared in example 2;
FIG. 3 is a graph showing the effect of oil phase species on SERS signals;
FIG. 4 is a graph showing the effect of n-hexane volume on SERS signals;
FIG. 5 is a graph showing the effect of phase transfer catalyst species on SERS signals;
FIG. 6 is a graph of the effect of cetyl trimethylammonium bromide volume on SERS signals;
FIG. 7 is a graph showing the effect of vortex mixing time on SERS signal.
Detailed Description
The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.
Example 1:
the method for preparing the nano Ag sol surface enhanced Raman substrate comprises the following steps:
taking 50 mL of AgNO with the mass concentration of 0.08 percent3Mixing the water solution and 25 mL of PVA water solution with the mass fraction of 0.1 percent for 5 min by ultrasonic treatment, averagely dividing the obtained mixed solution into three batches, adding the three batches of the mixed solution into 150 mL of ice-cold NaBH with the mass concentration of 0.008 percent4In a 250 ml flask of aqueous solution, the color of the solution immediately changed from colorless to brownish yellow with vigorous stirring, and finally the mixture was boiled for about 1 h to decompose excess NaBH4Stopping heating, stirring, cooling to room temperature to obtain Ag nano sol, placing in 4Refrigerating in a refrigerator at the temperature of DEG C for later use. The Ag nanosol prepared in this example 1 was transferred to a copper mesh containing a carbon-supported film, then dried with nitrogen, and subjected to TEM characterization test, with the test results shown in fig. 1 a.
Example 2:
a method for rapidly preparing a surface enhanced Raman substrate of a nano Ag film by a liquid-liquid interface comprises the following steps:
1) taking 50 mL of AgNO with the mass concentration of 0.08 percent3Mixing the water solution and 25 mL of PVA water solution with the mass fraction of 0.1 percent for 5 min by ultrasonic treatment, averagely dividing the obtained mixed solution into three batches, adding the three batches of the mixed solution into 150 mL of ice-cold NaBH with the mass concentration of 0.008 percent4In a 250 ml flask of aqueous solution, the color of the solution immediately changed from colorless to brownish yellow with vigorous stirring, and finally the mixture was boiled for about 1 h to decompose excess NaBH4Stopping heating, stirring and cooling to room temperature to obtain Ag nano sol, and refrigerating for later use; (step 1) transferring the Ag nano sol prepared in the step 1 to a cuvette, and carrying out ultraviolet spectrum test on a sample to be tested, wherein the test result is shown as a curve a in figure 2);
2) putting 380 mu L of the Ag nano sol obtained in the step 1) into a centrifuge tube, adding 380 mu L of n-hexane and 20 mu L of hexadecyl trimethyl ammonium bromide, transferring the centrifuge tube into a Scilogex MX-F fixed vortex mixer, carrying out vortex mixing for 40s at 2500r/min to form an emulsion in the centrifuge tube, standing, separating the emulsion into clear water and n-hexane phases, forming an Ag nano film with metallic luster at the interface of the water and n-hexane phases, inverting and opening the centrifuge tube to remove the upper n-hexane phase to obtain the Ag nano film which is floated on the surface of the water phase, namely the nano Ag film surface enhanced Raman substrate. The obtained Ag nano film is transferred to a copper net containing a carbon support film, then is dried by nitrogen, and is subjected to TEM characterization test, and the test result is shown in figure 1 b. Transferring the Ag nano film prepared in the step 2) onto a quartz plate, and carrying out ultraviolet spectrum test on a sample to be tested, wherein the test result is shown as a curve b in fig. 2.
As can be seen from comparing fig. 1a and 1b, the density between the particles in fig. 1b is very high compared to fig. 1a, but there is still some gap between the particles in fig. 1b, which may be caused by the transfer of the Ag nano-film to the copper mesh containing the carbon support film, but a dense nano-film is formed between the particles as a whole, and the particle size of the particles is about 20nm, thereby proving that the Ag nano-film prepared in this example 2 is very favorable for mutual plasma coupling and hot spot generation.
According to the present invention, when comparing the Ag nanosol prepared in example 1 with the Ag nanomembrane prepared in example 2, the Ag nanomembrane prepared in example 2 was visually observed, and a layer of nano Ag film having metallic luster was exhibited at the interface between water and n-hexane.
As can be seen from the curves a and b in fig. 2, the maximum uv absorption wavelength of the Ag nano-sol is 390 nm, and the maximum uv absorption wavelength of the Ag nano-film is 576 nm. SERS resonance is sensitive when a local field is enhanced, and occurs at a longer wavelength, mainly due to coupling plasma resonance, the Ag nano film generates red shift relative to a single nano particle of Ag nano sol, and has large local field enhancement, thereby achieving SERS enhancement.
Example 3:
a method for rapidly preparing a surface enhanced Raman substrate of a nano Ag film by a liquid-liquid interface comprises the following steps:
1) taking 50 mL of AgNO with the mass concentration of 0.08 percent3Mixing the water solution with 25 mL of PVA water solution with the mass fraction of 0.1 percent for 5 min by ultrasonic treatment, and adding the obtained mixed solution into 150 mL of ice-cold NaBH with the mass concentration of 0.008 percent in three batches on average4In a 250 ml flask of aqueous solution, the color of the solution immediately changed from colorless to brownish yellow with vigorous stirring, and finally the mixture was boiled for about 1 h to decompose excess NaBH4Stopping heating, stirring and cooling to room temperature to obtain Ag nano sol, and refrigerating for later use;
2) putting 380 mu L of Ag nano sol obtained in the step 1) into a centrifuge tube, and adding 20 mu L of 10-6Adding 380 mu L of n-hexane (the n-hexane is an oil phase) and 19 mu L of hexadecyl trimethyl ammonium bromide (the hexadecyl trimethyl ammonium bromide is a phase transfer catalyst) into a methanol solution of the enrofloxacin in mol/L, transferring the centrifugal tube into a Scilogex MX-F fixed vortex mixing instrument, and swirling at 2500r/minAnd (2) mixing by vortexing for 40 seconds, forming an emulsion in a centrifugal tube, standing, separating the emulsion into two phases of clear water and normal hexane, forming an Ag nano film with metallic luster at the interface of the water phase and the normal hexane phase, inverting and opening the centrifugal tube to remove the upper normal hexane phase to obtain a test system (the test system can be directly used for SERS test) with the Ag nano film floating on the surface of the water phase, wherein the Ag nano film is a surface enhanced Raman substrate, and molecules to be tested are directly adsorbed on the surface of the substrate.
Example 4:
investigating the influence of oil phase types on SERS signals:
the preparation process of the Ag nano film is repeated in the example 3, but the oil phase in the step 2) is replaced by dichloromethane, trichloromethane, benzene, toluene, cyclohexane or normal hexane with the same volume, and SERS tests are respectively carried out on the finally prepared Ag nano film, wherein the test method comprises the following steps: using an 632.18 nm light source as excitation light to inhibit the fluorescence interference of a sample to be tested, wherein the light energy variation range is 30-60 mW, the integration time is 20 s, and the test results are respectively shown in fig. 3; as can be seen from FIG. 3, when the oil phase is n-hexane, the prepared Ag nano-film has a larger signal intensity when subjected to SERS (surface enhanced Raman scattering) test.
Interfacial tension gamma for immiscible two-phase liquidso/wThe estimation can be done with equation (1):
wherein gamma isoIs the surface tension of the oil phase, gammawIt is the surface tension of the water that,
is the dispersion force of water. Table 1 shows the interfacial tension of different oils with respect to water estimated by the formula (1) after referring to the surface tension of each solvent. The strength of the adsorption capacity of the particles on the interface can be represented by the size delta E of the interface desorption energy of the particles, and the formula is shown in the specification
Where r is the radius of the nanoparticle, γo/wIs the interfacial tension, theta is the contact angle of the nanoparticles at the interface, and it can be seen that, regardless of the change of theta, there is always delta E < 0, therefore, the reduction of the interfacial energy is the main driving force for the interface self-assembly of the metal nanoparticles. According to the calculation of the formula (2), the larger the interfacial tension is, the more the interface energy is reduced, the easier the self-assembly is at the liquid-liquid two-phase interface, the more the amount of enrofloxacin carried to the interface by the Ag nano particles induced to the interface is, and the stronger the SERS signal is. In addition, as the density of dichloromethane and trichloromethane is higher than that of water, and the fine needle cylinder cannot extract all the oil phase at the lower layer, a part of enrofloxacin can be lost in the process of inverting the centrifugal tube and opening the centrifugal tube, so that the SERS signal is weaker.
It can be seen that the calculation results in table 1 correspond to the test results in fig. 3, and it can be inferred that which type of non-polar organic solvent is used as the oil phase by calculating the interfacial tension between the non-polar organic solvent and water, the Ag nano-film has a better self-assembly effect.
Example 5:
the effect of the volume of n-hexane on the SERS signal was investigated:
repeating the preparation process of the Ag nano film in the embodiment 3, but replacing the n-hexane adding amount in the step 2) by the volume ratio of Ag sol (380 μ L) to n-hexane of 1:0.25, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5 and 1:6, namely the adding volume of n-hexane is 95, 190, 380, 760, 1140, 1520, 1900 and 2280 μ L respectively, performing SERS test on the finally prepared molecules to be tested adsorbed on the Ag nano film, and repeating the embodiment 4 by the test method, wherein the test result is shown in FIG. 4;
the normal hexane is simple, easy to obtain and low in toxicity, and is very suitable for forming a water-oil interface as an oil phase. When the normal hexane/water two phases are vortexed, the original two phases can become emulsion, the existence of emulsion drops increases the area of a phase interface, the distance from Ag nano particles in a bulk phase to the interface is reduced, and finally the efficiency of interface self-assembly is improved. As can be seen from FIG. 4, the SERS signal is gradually enhanced with the increase of the amount of n-hexane, and is strongest when the addition amount of n-hexane is 380. mu.L, that is, the volume of the Ag sol and n-hexane is 1: 1. However, when the volume of n-hexane is larger than that of the Ag sol, the SERS signal obviously begins to weaken. From the perspective of solvent saving and signal intensity, the best effect is achieved when the volume of n-hexane is 380 muL.
Example 6:
investigating the influence of the phase transfer catalyst species on the SERS signal:
example 3 is repeated in the preparation process of the Ag nano-film, but when the Ag nano-film is applied to detection, the phase transfer catalyst in the step 2) is replaced by Cetyl Trimethyl Ammonium Bromide (CTAB), Dodecyl Trimethyl Ammonium Bromide (DTAB) or tetrabutyl ammonium bromide (TBAB) with the same volume, SERS tests are respectively carried out on the finally prepared Ag nano-films, the example 4 is repeated in the testing method, and the testing results are respectively shown in FIG. 5;
the surface activity efficiency of the phase transfer catalysts with different molecular structures is different because NaBH is used4Ag nano particles in the Ag colloid prepared by reduction have negative charges, so that a phase transfer catalyst with hydrophobic cations with different molecular structures and opposite charges to those of the metal Ag nano particles is selected. The advantage of this approach is that the hydrophobic cations are more prone to stay in the oil phase and do not adsorb directly onto the metal nanoparticles, thereby facilitating SERS measurements.
As is apparent from fig. 5, the SERS enhancement signals using the three phase transfer catalysts are almost the same. However, in the experimental process, the state of the formed Ag film is best after vortex mixing for 20 s when CTAB is added, and the Ag film is compact and uniform and is completely and flatly laid in the sample cover. This is because as the length of the alkyl carbon chain increases, its water solubility tends to decrease, and CTAB, which is much less water soluble than DTAB, will transfer faster into the oil phase by swirling, and thus the Ag nanoparticles attracted by the cationic groups will aggregate at a faster rate to the interface. Compared with CTAB and DTAB, TBAB has larger steric hindrance, and Ag nano particles with negative charges and TBA+Bonding is relatively difficult. However, it is believed that all three phase transfer catalysts result in complete film formation of Ag nanoparticles at the water-oil two-phase interface with increasing vortex time. CTAB is most preferable from the viewpoint of film formation efficiency.
Example 7:
investigating the influence of the addition of hexadecyl trimethyl ammonium bromide on the SERS signal:
repeating the example 3 in the preparation process of the Ag nano film, but replacing 17, 18, 19, 20, 21, 22 and 23 μ L of cetyl trimethyl ammonium bromide in the step 2) in the addition amount respectively, performing SERS test on finally prepared molecules to be tested adsorbed on the Ag nano film respectively, repeating the example 4 in the test method, and obtaining a test result as shown in FIG. 6;
the formation of a high quality film at the interface is largely dependent on the amount of phase transfer catalyst used. Too small an amount of the phase transfer catalyst does not break the interfacial equilibrium, which hinders the alignment by the interfacial ordering effect, whereas too much amount of the phase transfer catalyst makes it difficult to obtain a uniform thin film at the liquid-liquid interface. As can be seen from FIG. 6, the volume of the added cetyltrimethylammonium bromide has little influence on the SERS signal enhancement, and the SERS signal is relatively stable when the volume of the cetyltrimethylammonium bromide is 19 μ L, which means that the Ag film is relatively uniform, therefore, the optimal volume of the cetyltrimethylammonium bromide is 19 μ L from the viewpoint of the film forming state and the signal intensity.
Example 8:
investigating the influence of vortex mixing time on the SERS signal:
example 3 is repeated in the preparation process of the Ag nano film, but the vortex mixing time in step 2) is respectively replaced by 5, 10, 20, 30, 40, 50 and 60 seconds, the finally prepared molecules to be tested adsorbed on the Ag nano film are respectively subjected to SERS test, the test method is repeated in example 4, and the test result is shown in FIG. 7;
the cationic groups of cetyltrimethylammonium bromide hydrolyze to spontaneously form positive charges at the oil interface, which can then be electrostatically attracted to negatively charged Ag nanoparticles. This mechanical impact of swirling both increases the contact surface of the water and oil phases and increases the particle kinetic energy to accelerate particle motion and interface formation. The longer the vortex time, the greater the number of Ag nanoparticles per unit area, resulting in a denser Ag nanofilm. Therefore, the interval between adjacent Ag nano particles in the Ag nano film can be regulated and controlled by controlling the vortex time, so that the number of 'hot spots' is controlled, molecules near the hot spots can be excited, and remarkable SERS enhancement is shown.
As can be seen from fig. 7, when the vortex time is shorter, the SERS signal is weaker, and after the vortex time is increased, the SERS signal is significantly enhanced and shows a trend of being enhanced first and then weakened. When the vortex time is 40s, the SERS signal is strongest, and after the vortex time is further increased, the SERS signal is rather decreased, and after the vortex time is 40s, the decrease tendency becomes gentle. This is because as the vortex time increases, the number of Ag nanoparticles per unit area gradually increases, and adjacent Ag nanoparticles approach each other to generate "hot spots" to realize local surface plasmon resonance, and thus the SERS signal gradually increases and reaches a maximum. After the vortex time is further increased, the number of the Ag nano particles in a unit area is continuously increased, the Ag nano particles are forced to be crowded together, the Ag film is thickened, a single-layer structure is possibly lost, molecules to be detected cannot enter gaps of the Ag film, and SERS signals can be weakened after the vortex time is too long.
The statements in this specification merely set forth a list of implementations of the inventive concept and the scope of the present invention should not be construed as limited to the particular forms set forth in the examples.
Claims (9)
1. A method for rapidly preparing a surface enhanced Raman substrate of a nano Ag film by a liquid-liquid interface is characterized by comprising the following steps:
1) taking AgNO3Mixing the aqueous solution and the PVA aqueous solution for 3-10 min by ultrasonic treatment, and adding the obtained mixed solution into ice-cold NaBH in two to four batches on average4In the water solution, the color of the solution is observed to change from colorless to brown yellow immediately under the condition of vigorous stirring, and then the mixture is boiled for 0.5 to 1.5 hours to decompose excessive NaBH4Stopping heating, stirring and cooling to room temperature to obtain Ag nano sol, and refrigerating for later use;
2) placing the Ag nano sol obtained in the step 1) in a centrifugal tube, adding a phase transfer catalyst and a nonpolar organic solvent, transferring the centrifugal tube into a vortex mixer, carrying out vortex mixing, forming an emulsion in the centrifugal tube, standing, separating the emulsion into clear water and oil phases, forming a Ag nano film with metallic luster at a water-oil interface, removing an oil phase, and obtaining the Ag nano film on the surface of a water phase, namely the nano Ag film surface enhanced Raman substrate.
2. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film through the liquid-liquid interface according to claim 1, wherein in the step 1), the mass fraction of the PVA aqueous solution is 0.08-0.12%; AgNO3The mass fraction of the aqueous solution is 0.06-0.10%, and NaBH4The mass fraction of the aqueous solution is 0.006-0.010%, and NaBH4Aqueous solution, AgNO3The volume ratio of the aqueous solution to the PVA aqueous solution is 8-12: 1-3: 1.
3. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film according to claim 2, wherein the PVA aqueous solution is 0.1% by mass; AgNO3The mass fraction of the aqueous solution is 0.08 percent, and the NaBH is added4The mass fraction of the aqueous solution is 0.008 percent, and NaBH is added4Aqueous solution, AgNO3The volume ratio of the aqueous solution to the aqueous PVA solution was 10: 2: 1.
4. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film according to claim 1, wherein in step 2), the non-polar organic solvent is dichloromethane, chloroform, benzene, toluene, cyclohexane or n-hexane, preferably n-hexane.
5. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film according to claim 1, wherein in step 2), the phase transfer catalyst is cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide or tetrabutyl ammonium bromide, preferably cetyl trimethyl ammonium bromide.
6. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film through the liquid-liquid interface according to claim 1, wherein in the step 2), the volume ratio of the Ag nano sol to the non-polar organic solvent is 1: 0.25-6, and preferably 1: 1.
7. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film through the liquid-liquid interface according to claim 1, wherein in the step 2), the volume ratio of the phase transfer catalyst to the Ag nano sol is 1: 16-23, and preferably 1: 20.
8. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film through the liquid-liquid interface according to claim 1, wherein in the step 2), the rotational speed of the centrifugal tube in a vortex mixer for vortex mixing is 2400-2600 r/min, and the time for vortex mixing is 5-60 s.
9. The method for rapidly preparing the surface-enhanced Raman substrate with the nano Ag film according to claim 1, wherein the rotation speed of the centrifugal tube in a vortex mixer is 2500r/min, and the vortex mixing time is 40 s.
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| CN114535593A (en) * | 2021-11-26 | 2022-05-27 | 河南农业大学 | Preparation method and application of AgNPs @ SASP substrate material |
| CN117092087A (en) * | 2023-07-31 | 2023-11-21 | 广东海洋大学 | Method for separating nano plastics and identification method of nano plastics |
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