CN116380865A - CNTsAg@AuNPsSiO2 combined SERS substrate, preparation method and pesticide detection method - Google Patents

Abstract

The invention discloses a CNTsAg@AuNPsSiO2 combined SERS substrate, wherein CNTsAg@AuNPs solution is dripped on a silica glass sheet, and after drying, the CNTsAg@AuNPsSiO2 combined SERS substrate is formed, wherein the CNTsAg@AuNPs solution contains 20-80% of gold in a surface gold shell, 16-76% of silver in a core silver core and 3-25% of multi-wall carbon nanotubes by mass. The invention can realize large-area uniform construction of the SERS substrate with a complex structure with low cost and relatively simple structure.

Description

CNTsAg@AuNPsSiO2 combined SERS substrate, preparation method and pesticide detection method

technical field

The invention relates to the technical field of analysis and detection of pesticide residues, in particular to a SERS substrate combined with CNTsAg@AuNPsSiO2 (the surface of multi-walled carbon nanotubes is combined with gold-shell silver core nanoparticles and silicon dioxide material composite SERS substrate), a preparation method and a pesticide Detection method.

Background technique

With the development of agricultural technology, in order to achieve the expected standard for the harvest of agricultural products, it is a common method to use pesticides to treat crops. However, after the crops mature, there will still be pesticide residues on the agricultural products. When the residual amount exceeds a certain standard, it will cause irreversible damage to the human body. Therefore, the pesticide residues on the surface of the crops should be tested after they mature.

Nowadays, many pesticide detection methods have been proposed, such as thin-layer chromatography, gas chromatography, high-performance liquid chromatography, supercritical fluid chromatography, gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, high-performance capillary electrophoresis and other traditional pesticide residue detection methods, although stable Reliable and reproducible, but the sample pretreatment is complex, the detection time is long, and the detection results are lagging behind, so it is not suitable for on-site detection. Therefore, it is of great practical significance to study rapid and efficient pesticide residue detection methods. Surface-enhanced Raman spectroscopy (SERS) technology has the advantages of high sensitivity, strong anti-interference, and quenching of fluorescence, and surface-enhanced Raman spectroscopy can generally enhance the signal by 10 ^-5 to 10 ^-6 times, reaching the standard for practical applications , so it has great advantages and application potential in the rapid detection of pesticide residues in agricultural and sideline products.

To use a Raman spectrometer for analysis and testing, it is necessary to select a suitable Raman substrate and detect analytes through the surface-enhanced Raman effect of the substrate. At present, domestic and foreign studies on surface-enhanced Raman spectroscopy focus on the two mechanism enhancement methods of electromagnetic field enhancement (EM) and chemical enhancement (CM), among which more attention is paid to the preparation of surface-enhanced Raman substrates, and now Most of the substrate preparation processes are complicated, the preparation conditions are single and the requirements are too high, it is not easy to mass-produce, the application is relatively simple, and the cost is slightly high. Therefore, it is necessary to seek a more economical and reliable preparation method for high-activity SERS substrates.

Contents of the invention

The purpose of the present invention is to provide a SERS substrate combined with CNTsAg@AuNPsSiO2, a preparation method and a pesticide detection method. The present invention can achieve a large-area uniform construction of a SERS substrate with a complex structure at low cost and relatively simple.

In order to achieve this goal, a CNTsAg@AuNPsSiO2-bonded SERS substrate designed in the present invention is characterized in that: the CNTsAg@AuNPs solution is dropped on a silica glass sheet, and after drying, a CNTsAg@AuNPsSiO2-bonded SERS substrate is formed. The mass percentage of each component of CNTsAg@AuNPs in the CNTsAg@AuNPs solution is 20-80% of gold in the surface gold shell, 16-76% of silver in the inner silver core and 3-25% of multi-walled carbon nanotubes.

A method for preparing the above-mentioned CNTsAg@AuNPsSiO2 combined SERS substrate, characterized in that it comprises the following steps:

Step 1: Add AgNO ₃ standard solution in deionized water;

Step 2: adding the multi-walled carbon nanotube dispersion solution to the solution obtained in step 1 and mixing to obtain a mixed solution;

Step 3: Using an oil bath to magnetically stir and heat the above mixed solution;

Step 4: Add sodium citrate solution to the magnetically stirred and heated solution in Step 3, continue heating, take it out and cool it to room temperature;

Step 5: Centrifuge the cooled sample in step 4, then disperse the centrifuged product in deionized water, store it at room temperature for later use, and obtain the silver in the gold-shell-silver-core structure;

Step 6: Utilize hypochloroauric acid solution, sodium hydroxide solution, _Na2SO3 solution and water to prepare gold growth solution for subsequent use _;

Step 7: mixing deionized water, polyvinylpyrrolidone (PVP) solution, ascorbic acid solution, NaOH solution, _Na2SO3 solution and gold growth solution to obtain the gold in the gold-shell-silver-core structure _;

Step 8: Put the spare sample solution in step 5 and the spare sample solution in step 7 to stand at room temperature to generate a CNTs/Ag@AuNPs solution. At this time, the gold shell and silver core are adsorbed on the multi-walled carbon nanotubes, and the The mass percentage of each component of CNTsAg@AuNPs in the CNTsAg@AuNPs solution is 20-80% of gold in the surface gold shell, 16-76% of silver in the inner silver core and 3-25% of multi-walled carbon nanotubes;

Step 9: Add the CNTs/Ag@AuNPs solution generated in step 8 to deionized water, perform ultrasonic cleaning, and then perform centrifugation, take out the bottom mixture collected after centrifugation, add 5ml deionized water for ultrasonic cleaning, and Save it for future use, and prepare the CNTs/Ag@AuNPs substrate;

Step 10: Drop the sample solution prepared in step 9 onto a silica glass slide to dry naturally, and finally obtain a CNTsAg@AuNPs SiO2-bound SERS substrate.

In step 1 of the above technical solution, add _AgNO3 standard solution to deionized water, stir, and dilute 0.01-1mol/L _AgNO3 to 0.001-0.01mol/L range, the volume of deionized water and _AgNO3 standard solution The ratio is 57～95:3～5.

In step 2 of the above-mentioned technical solution, stir the mixed solution obtained in step 2 with a glass rod for 5 to 15 minutes, cover with a plastic wrap (to prevent volatilization) and let it stand for 20 to 40 minutes, so that the Ag ions can be fully mixed with the multi-walled carbon nanotubes. surface contact absorption;

In the step 2, the volume ratio of the stirred solution in the step 1 to the multi-walled carbon nanotube solution is 50-100:0.25-0.5.

In step 3 of the above technical solution, the above mixed solution is magnetically stirred and heated to 90-100°C using an oil bath with a rotational speed of 100-200r/min. This oil bath ensures a constant temperature condition, thereby reducing the impact of temperature fluctuations on The effect of chemical reactions.

In step 4 of the above technical solution, a sodium citrate solution with a mass fraction of 0.5-1% is added, and the volume ratio of the mixed solution in the step 2 to the sodium citrate solution is 96-201:2-4;

In the step 4, continue heating at 90-100°C for 30-45 minutes, then take it out and cool it to room temperature. At this time, the strong reducing property of the sodium citrate solution in high-temperature water reduces the Ag ions in the _AgNO3 to Ag nanometers. particles.

In step 5 of the above technical solution, the centrifugation process is to use a centrifuge to centrifuge at a speed of 4000 to 4800r/min for 80 to 100 minutes, and the centrifuged product is dispersed in 5mL of deionized water. Selecting centrifugation can greatly shorten the separation time .

In _step 6 of the above technical solution, the volume ratio of hypochloroauric acid solution to water is 0.11-0.33:2.27-6.81, the volume ratio of sodium hydroxide solution to water is 0.01-0.05:1.14-5.68, and the _Na2SO3 solution The volume ratio with water is 2~5:3.03~7.57;

The mass percentage range of the hypochloroauric acid in the hypochloroauric acid solution is 1-3%;

The concentration range of sodium hydroxide solution is 0.1～0.5mol/L;

The concentration range of the Na ₂ SO ₃ solution is 0.01-0.05 mol/L.

In step 7 of the above technical solution, the volume ratio of deionized water to gold growth solution is 2-4:3-4.71, the volume ratio of polyvinylpyrrolidone solution to gold growth solution is 0.5-3:2-12, and the ascorbic acid solution and The volume ratio of the gold growth solution is 0.1～0.5:2～10, the volume ratio of the NaOH solution to the gold growth solution is 0.1～ _0.5 :2～10, and the volume ratio of the _Na2SO3 solution to the gold growth solution is 0.01～0.1: 0.8～8;

The polyvinylpyrrolidone solution is a polyvinylpyrrolidone solution with a mass fraction of 2 to 5%, and the relative molecular mass is 40000;

The concentration range of ascorbic acid solution is 0.1～1mol/L;

The concentration range of NaOH solution is 0.1～1mol/L;

The concentration range of the Na ₂ SO ₃ solution is 0.1-1 mol/L.

In step 9 of the above technical solution, the CNTs/Ag@AuNPs were taken out by centrifuging the CNTs/Ag@Au NPs sample solution, the centrifugation speed was selected at 4500r/min, and centrifuged 5 times for 10 minutes each time.

A pesticide spectral detection method using the above-mentioned SERS substrate combined with CNTsAg@AuNPsSiO2. The detection method is to drop the probe molecule rhodamine and pesticides on the SERS substrate combined with CNTsAg@AuNPsSiO2, and then wait for it to dry naturally. After drying, perform Raman detection to obtain the Raman test pattern of the pesticide, which is thiram or diquat.

Compared with the prior art, the present invention improves structure and preparation, and has the following technical effects:

1. Structurally, adopt steps 5 and 7 to finally obtain core-shell nanoparticles composed of gold and silver with strong electromagnetic enhancement capabilities, and combine them with carbon nanotubes to further enhance the Raman signal by using semiconductor charge transfer. It can greatly enhance the Raman signal, and finally achieve the purpose of improving the detection limit, and obtain better results with a simple structure.

2. Since the preparation steps can be completed at normal temperature, and the operation is simple, the time required for the preparation is not long, and the gold-shell silver core structure can be prepared in a short time, so the preparation method is simple and the time required is short. Low cost and easy to reproduce.

3. Because during the preparation process, core-shell nanoparticles composed of gold and silver with strong electromagnetic enhancement ability are obtained, which greatly enhances the Raman signal, and combined with multi-walled carbon nanotubes, it can detect lower concentrations of thiram in application Double, strong uniformity and stability.

Description of drawings

Figure 1 is the flow chart of CNTs/Ag@AuNPs/SiO ₂ SERS substrate preparation;

Figure 2 is the TEM image of the CNTs/Ag@AuNPs/SiO ₂ SERS substrate;

Figure 3 is a physical map of the CNTs/Ag@AuNPs/SiO ₂ SERS substrate;

Figure 4 is a Raman test diagram of the CNTs/Ag@AuNPs/SiO ₂ SERS substrate using the probe molecule rhodamine;

Figure 5a is the stability Raman test graph of CNTs/Ag@AuNPs/SiO ₂ SERS substrate;

Figure 5b is the uniformity Raman test pattern of CNTs/Ag@AuNPs/SiO ₂ SERS substrate;

Figure 6 is the Raman test chart of the CNTs/Ag@AuNPs/SiO ₂ SERS substrate using the pesticide thiram;

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

Example 1

A CNTsAg@AuNPsSiO2-bound SERS substrate, where the CNTsAg@AuNPs solution is dropped onto a silica glass sheet, and after drying, a CNTsAg@AuNPsSiO2-bound SERS substrate is formed, the mass percentage of each component of CNTsAg@AuNPs in the CNTsAg@AuNPs solution 42.1% gold in the surface gold shell, 52.6% silver in the inner core silver core and 5.3% multi-walled carbon nanotubes;

The preparation method of the SERS substrate combined with CNTsAg@AuNPsSiO2 comprises the following steps:

Step 1: Add 5ml of AgNo ₃ standard solution into 95ml of deionized water and stir for 10 minutes, the solution is colorless at this time;

Step 2: Add 0.5 ml of multi-walled carbon nanotubes to the above colorless solution, mix them, and stir for 5 minutes, at this time, the solution changes from colorless to black;

Step 3: Using an oil bath with a rotational speed of 200r/min to magnetically stir the above black solution and heat it to 95°C;

Step 4: After heating to 95°C, add 2mL of sodium citrate solution with a mass fraction of 1% to the black solution, keep the temperature at 95°C and heat and stir for 40 minutes, take it out and cool to room temperature after 40 minutes;

Step 5: Centrifuge the black solution sample cooled to room temperature, the centrifugation speed is 4500r/min, and the centrifugation time is 90 minutes. After centrifugation, disperse the centrifuged product in 5mL deionized water, and store it at room temperature for later use.

Step 6: Add 4.54ml of deionized water to a 20ml glass bottle, then add 220μl of hypochloroauric acid (2% mass), then add 40μl of sodium hydroxide (0.2mol/L), and finally add 3ml of Na ₂ SO ₃ , to obtain a colorless gold growth solution;

Step 7: Add 2.55 mL of deionized water to a 25 mL glass bottle, add 1 mL of polyvinylpyrrolidone (5wt%, Mw 40000), continue to add 200 μL of ascorbic acid (0.5mol/L), continue to add 200 μL of NaOH (0.5mol /L), continue to add 50 μL Na ₂ SO ₃ (0.1mol/L), and finally add 4ml of gold growth solution;

Step 8: Put the spare sample solution in step 5 and the spare sample solution in step 7 to stand at room temperature to generate CNTs/Ag@AuNPs;

Step 9: Add the CNTs/Ag@AuNPs solution generated in step 8 into deionized water, and perform ultrasonic cleaning, then centrifuge at a speed of 4500r/min, centrifuge 5 times for 10 minutes each time, and collect after centrifugation After the bottom mixture was taken out, 5 mL of deionized water was added, ultrasonically oscillated for ten minutes with an ultrasonic cleaner, and stored at room temperature for later use, with an ultrasonic frequency of 45 Hz;

Step 10: Drop the sample solution prepared in step 9 onto a silica glass slide to dry naturally, and finally obtain a CNTsAg@AuNPs SiO2-bound SERS substrate. Figure 2 is the TEM image of the CNTs/Ag@AuNPs/SiO ₂ SERS substrate. It can be seen from the figure that the gold-shell silver core nanoparticles are adsorbed on the multi-walled carbon nanotubes, which shows that the preparation of the substrate structure is completely feasible and the effect is good; Figure 3 This is the actual photo of the substrate after drying.

Step 11: Place the CNTsAg@AuNPs SiO2-bound SERS substrates in step 10 for 1 day, 7 days, 15 days, 30 days and 45 days, respectively, and then Rhodamine at a concentration of 10 ^-8 mol/L was detected at that time, and the results are shown in Figure 5a. It can be seen that the substrate can still detect rhodamine well after being placed for a long time of 45 days, which proves that the substrate has good stability.

Step 12: Perform Raman detection on the SERS substrate combined with CNTsAg@AuNPs SiO2 in step 10, and randomly select 5 test points, as shown in Figure 5b. It can be seen from the figure that the signals of the 5 randomly selected points are good, and the substrate has good uniformity.

Example 2:

A CNTsAg@AuNPsSiO2-bound SERS substrate, where the CNTsAg@AuNPs solution is dropped onto a silica glass sheet, and after drying, a CNTsAg@AuNPsSiO2-bound SERS substrate is formed, the mass percentage of each component of CNTsAg@AuNPs in the CNTsAg@AuNPs solution It is 41.1% of gold in the surface gold shell, 54.8% of silver in the inner core silver core and 4.1% of multi-walled carbon nanotubes;

The preparation method of the SERS substrate combined with CNTsAg@AuNPsSiO2 comprises the following steps:

Step 1: Add 4ml of AgNo ₃ standard solution into 95ml of deionized water and stir for 10 minutes, the solution is colorless at this time;

Step 2: Add 0.3 ml of multi-walled carbon nanotubes to the above colorless solution, mix them, and stir for 15 minutes, at which point the solution changes from colorless to black;

Step 3: Using an oil bath with a rotational speed of 100r/min to magnetically stir the above black solution and heat it to 100°C;

Step 4: After heating to 100°C, add 4mL sodium citrate solution with a mass fraction of 0.5% to the black solution, keep the temperature at 100°C and heat and stir for 35 minutes, take it out and cool to room temperature after 35 minutes;

Step 5: Centrifuge the black solution sample cooled to room temperature. The centrifugation speed is 4600r/min, and the centrifugation time is 85 minutes. After centrifugation, the centrifuged product is dispersed in 6mL deionized water and stored at room temperature for later use.

Step 6: Add 4ml of deionized water to a 20ml glass bottle, then add 200μl of hypochloroauric acid (2% mass), then add 50μl of sodium hydroxide (0.2mol/L), and finally add 5ml of Na ₂ SO ₃ , to obtain a colorless gold growth solution;

Step 7: Add 2 mL of deionized water to a 25 mL glass bottle, add 1.5 mL of polyvinylpyrrolidone (5wt%, Mw 40000), continue to add 220 μL of ascorbic acid (0.5mol/L), continue to add 220 μL of NaOH (0.5mol /L), continue to add 40 μL Na ₂ SO ₃ (0.1mol/L), and finally add 3ml of gold growth solution;

Step 8: Put the spare sample solution in step 5 and the spare sample solution in step 7 to stand at room temperature to generate CNTs/Ag@AuNPs;

Step 9: Add the CNTs/Ag@AuNPs solution generated in step 8 into deionized water, and perform ultrasonic cleaning, then centrifuge at a speed of 4500r/min, centrifuge 5 times for 10 minutes each time, and collect after centrifugation After the bottom mixture was taken out, 5 mL of deionized water was added, ultrasonically oscillated for ten minutes with an ultrasonic cleaner, and stored at room temperature for later use, with an ultrasonic frequency of 45 Hz;

Step 10: Drop the sample solution prepared in step 9 onto a silica glass slide to dry naturally, and finally obtain a CNTsAg@AuNPs SiO2-bound SERS substrate.

Step 11: Place the CNTsAg@AuNPs SiO2-bound SERS substrates in step 10 for 1 day, 7 days, 15 days, 30 days and 45 days, respectively, and then At this time, rhodamine at a concentration of 10 ^-8 mol/L was detected to explore the stability of the substrate.

Step 12: Perform Raman detection on the CNTsAg@AuNPs SiO2-bound SERS substrate in step 10, and randomly select 5 test points to explore the uniformity of the substrate.

Test case 1:

A rhodamine solution was prepared, and 0.0479 g of rhodamine red solid powder was weighed with an electronic balance and added to 100 mL of deionized water to obtain a 10 ^-3 mol/L R6G mother solution. Use a test tube to measure 1mL of ^10-3 mol/L R6G mother liquor into the centrifuge tube, then add deionized water to make it volume to 10mL to obtain a ^10-4 mol/L R6G solution (i.e. 1ml R6G+9ml deionized water dilution), and so on to 10 ^-12 mol/L.

Rhodamine solutions of different concentrations were dropped onto the silica glass sheet of Example 7, and then left to stand for natural drying, and Raman detection was performed after natural drying. Figure 4 is the Raman test graph of the CNTs/Ag@AuNPs/SiO ₂ bound SERS substrate obtained in Example 1 using different concentrations of the probe molecule rhodamine. It can be seen from Figure 4 that the probe molecule rhodamine is at a low concentration of ¹⁰ mol/L can still be detected, it can be seen that the detection performance of the substrate is good.

Test case 2:

Configure thiram solution:

10mg/L thiram bis-ethanol solution: Weigh 0.01g thiram bis-ethanol powder with an electronic balance, add it to 100mL ethanol, and ultrasonically oscillate for 2min to prepare 10mg/L thiram bis-ethanol solution;

5mg/L thiram diethyl alcohol solution: take 5mL from the 10mg/L thiram diethyl alcohol solution with a rubber dropper, add 5mL ethanol to form a 5mg/L thiram diethyl alcohol solution;

1mg/L thiram bis-ethanol solution: Take out 1mL from the 10mg/L thiram bis-ethanol solution with a rubber dropper, add 9mL ethanol to form a 1mg/L thiram bis-ethanol solution;

0.1mg/L thiram bis-ethanol solution: Take out 1mL from the 1mg/L thiram bis-ethanol solution with a rubber dropper, add 9mL ethanol to form a 0.1mg/L thiram bis-ethanol solution.

Then switch to different concentrations of thiram solution and let it stand at room temperature for later use.

Thiram solutions of different concentrations were dropped onto the silica glass sheet of Example 7, and then left to wait for natural drying, and Raman detection was performed after natural drying. Figure 6 is the Raman test graph of the CNTs/Ag@AuNPs/SiO ₂ combined SERS substrate using different concentrations of the pesticide thiram. It can be seen from Figure 6 that the pesticide thiram can still be detected at a low concentration of 0.01mg/L. The substrate has good detection performance and sensitivity, and is suitable for the detection of pesticide thiram double residues.

The content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims (10)

1. A cntsag@aunpsssio2 bonded SERS substrate characterized by: and the CNTsAg@AuNPs solution is dripped on a silica glass sheet, and after drying, a CNTsAg@AuNPsSiO2 combined SERS substrate is formed, wherein the CNTsAg@AuNPs solution comprises 20-80% of gold in a surface gold shell, 16-76% of silver in a core silver core and 3-25% of multi-wall carbon nano tubes by mass percent.

2. A method of preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, comprising the steps of:

step 1: at the position ofAdding AgNO into deionized water ₃ A standard solution;

step 2: adding the multiwall carbon nanotube dispersion solution into the solution obtained in the step 1, and mixing to obtain a mixed solution;

step 3: magnetically stirring and heating the mixed solution by using an oil bath mode;

step 4: adding sodium citrate solution into the solution obtained after the magnetic stirring and heating in the step 3, continuously heating, taking out the solution, and cooling to room temperature;

step 5: centrifuging the cooled sample in the step 4, dispersing the centrifuged product in deionized water, and preserving at room temperature for standby to obtain silver in the gold-shell silver-core structure;

step 6: using a solution of hypochlorous acid, a solution of sodium hydroxide and Na ₂ SO ₃ Preparing a gold growth solution by the solution and water;

step 7: deionized water, polyvinylpyrrolidone solution, ascorbic acid solution, naOH solution, na ₂ SO ₃ Mixing the solution with gold growth solution for standby to obtain gold in the gold shell silver core structure;

step 8: standing the sample solution prepared in the step 5 and the sample solution prepared in the step 7 at room temperature to generate CNTs/Ag@AuNPs solution, wherein the CNTsAg@AuNPs solution comprises 20-80% of gold in a surface gold shell, 16-76% of silver in a silver core and 3-25% of multi-wall carbon nano tubes by mass percent;

step 9: adding deionized water into the CNTs/Ag@AuNPs solution generated in the step 8, performing ultrasonic cleaning, performing centrifugal treatment, taking out a bottom mixture collected after centrifugation, adding deionized water, performing ultrasonic cleaning, and preserving at room temperature for later use;

step 10: and (3) dripping the sample solution prepared in the step (9) onto a silica glass sheet, and naturally airing.

3. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 1, agNO is added into deionized water ₃ Standard solution, inStirring the mixture in a row, wherein the mixture is stirred, 0.01 to 1mol/L AgNO ₃ Diluting to 0.001-0.01 mol/L, deionized water and AgNO ₃ The volume ratio of the standard solution is 57-95:3-5.

4. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 2, the mixed solution obtained in the step 2 is stirred for 5 to 15 minutes by a glass rod, and is kept stand for 20 to 40 minutes, so that Ag ions can be fully contacted and absorbed with the surface of the multi-wall carbon nano tube;

in the step 2, the volume ratio of the stirred solution in the step 1 to the multi-wall carbon nano tube solution is 50-100:0.25-0.5.

5. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 3, the mixed solution is magnetically stirred by using an oil bath mode with the rotating speed of 100-200 r/min and heated to 90-100 ℃.

6. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 4, adding a sodium citrate solution with the mass fraction of 0.5-1%, wherein the volume ratio of the mixed solution in the step 2 to the sodium citrate solution is 96-201: 2 to 4;

in the step 4, the mixture is continuously heated at 90-100 ℃ for 30-45 minutes and then taken out to be cooled to room temperature.

7. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 5, the centrifugal treatment process is to utilize a centrifugal machine to centrifuge for 80-100 minutes at the rotating speed of 4000-4800 r/min, and the centrifuged product is dispersed in deionized water.

8. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 6, the volume ratio of the chloroauric acid solution to the water is 0.11-0.33:2.27-681, the volume ratio of sodium hydroxide solution to water is 0.01-0.05:1.14-5.68, na ₂ SO ₃ The volume ratio of the solution to the water is 2-5:3.03-7.57;

the mass percentage of the chloroauric acid in the chloroauric acid solution is 1-3%;

the concentration range of the sodium hydroxide solution is 0.1-0.5 mol/L;

Na ₂ SO ₃ the concentration range of the solution is 0.01-0.05 mol/L.

9. The method for preparing a cntsag@aunpsssio2 bonded SERS substrate according to claim 1, wherein: in the step 7, the volume ratio of deionized water to gold growth solution is 2-4: 3 to 4.71, the volume ratio of polyvinylpyrrolidone solution to gold growth solution is 0.5 to 3:2 to 12, the volume ratio of ascorbic acid solution to gold growth solution is 0.1 to 0.5:2 to 10, the volume ratio of NaOH solution to gold growth solution is 0.1 to 0.5:2 to 10, na ₂ SO ₃ The volume ratio of the solution to the gold growth solution is 0.01-0.1:0.8-8;

the polyvinylpyrrolidone solution is polyvinylpyrrolidone solution with mass fraction of 2-5% and relative molecular mass of 40000;

the concentration range of the ascorbic acid solution is 0.1-1 mol/L;

the concentration range of the NaOH solution is 0.1-1 mol/L;

Na ₂ SO ₃ the concentration range of the solution is 0.1-1 mol/L.

10. A method for pesticide spectrum detection using the cntsag@aunpssio2-bound SERS substrate of claim 1, characterized by: the detection mode is that a probe molecule rhodamine and pesticide are dripped on a SERS substrate combined with CNTsAg@AuNPsSiO2, then the mixture is stood for waiting for natural airing, and Raman detection is carried out after the natural airing, so that a Raman test chart of the pesticide is obtained.

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