CN113668029B - Thin film composed of rough gold nanoparticles and its preparation method and use - Google Patents

Abstract

The invention relates to a film formed by rough gold nanoparticles, which mainly comprises a plurality of large gold nanoparticles positioned on a conductive substrate and a plurality of small gold nanoparticles coated on the surfaces of the large gold nanoparticles, wherein the large gold nanoparticles are stacked into a layer; the particle size of the small gold nanoparticles is 15-80nm, and the particle size of the large gold nanoparticles is 200-900nm. The thin film structure that coarse gold nanoparticle constitutes is connected by the gold nanoparticle stack of 2 to 4 layer surface irregularities and is formed, and this kind of structure makes has more gaps between them, can provide numerous SERS hot spots, and this kind of thin film structure has good structural homogeneity moreover, provides reliable guarantee for the homogeneity of SERS signal to the SERS sensitivity and the signal homogeneity that make the purpose product all obtain showing and promote. It can be used as an active substrate for surface enhanced Raman scattering to detect organic dyes.

Description

Thin film composed of rough gold nanoparticles and its preparation method and use

technical field

The invention relates to a gold nano material and its preparation method and application, in particular to a thin film composed of rough gold nanoparticles and its preparation method and application.

Background technique

Surface-enhanced Raman scattering (SERS) spectroscopy can provide fingerprint information of molecular vibrations, and has the advantages of fingerprint identification, high sensitivity and fast detection speed. The generation of SERS spectra is inseparable from the SERS substrate. In order to realize the application of SERS detection technology, researchers have developed many types of SERS substrates. Gold nanostructured SERS substrates have attracted extensive attention because of their high chemical stability, excellent SERS activity, and stable performance. The signal of the SERS substrate mainly comes from the hot spot of the electromagnetic field. Narrow noble metal nanogaps and nanoscale rough surfaces can both generate hot spots. In order to obtain gold nanostructures with a large number of hot spots, people have made some useful attempts and efforts, such as entitled "Facile Fabrication of High-Density Sub-1-nm Gaps from Au Nanoparticle Monolayers as Reproducible SERSSubstrates", Adv.Funct.Mater. 2016, 26, 8137–8145 (“Facile preparation of single-layer gold nanoparticle films with high density subnanometer gaps as reproducible SERS substrates”, Advanced Functional Materials, Vol. 26, pp. 8137-8145, 2016) article. The single-layer gold nanoparticle film mentioned in this article is a thin film assembled by a single layer of gold nanoparticles on a silicon wafer substrate; the preparation method is to first use the liquid surface self-assembly method to obtain a single-layer film assembled by gold nanoparticles , and then transfer the monolayer film directly to a clean silicon wafer surface to obtain the product. Although this product has strong light absorption at 633nm and 785nm, it has shortcomings with its preparation method; first, the gold nanoparticles in the product are only a single layer, which not only restricts its SERS activity, but also The uniformity is also very easy to be destroyed by the water waiting for the test solution, thereby seriously affecting the uniformity of its SERS signal; secondly, the preparation method cannot obtain a product with high SERS activity and is not subject to the water waiting for the test solution to destroy the uniformity of its SERS signal . For this reason, a method of electrodepositing a gold nanoparticle-assembled thin film on a conductive substrate sputtered with a gold film has been developed, such as the patent application number 2017103043375 filed on May 3, 2017, entitled "Gold Nanoparticle Assembly The invention patent of thin film and its preparation method and application". The thin film is a thin film with a thickness of 200nm-2μm covered with multiple layers of gold nanoparticles adhered to each other on a conductive substrate, wherein the particle size of the gold nanoparticles is 30-120nm; , to obtain a conductive substrate covered with a gold film on its surface, then use the graphite sheet as an anode, and place the conductive substrate covered with a gold film as a cathode in a gold electrolyte for electrodeposition at a constant current to obtain the desired product. The gold electrolyte used is a mixed solution of 0.2-10g/L chloroauric acid aqueous solution and 2-200g/L polyvinylpyrrolidone (PVP) aqueous solution, although what this preparation method obtains is a film assembled by multilayer gold nanoparticles , but both the preparation method and product morphology have room for improvement. For example, sputtering is used to sputter a layer of gold film on the surface of conductive glass, which makes this preparation method heavily dependent on sputtering equipment; secondly, the surface of gold nanoparticles obtained by sputtering is smooth, even if there are gaps between gold particles SERS hotspots are detected, but the amount of hotspots is still limited; again, it adds a surfactant polyvinylpyrrolidone to the gold electrolyte, which will be adsorbed on the surface of the prepared gold nanoparticles and is not easy to remove. Molecules, the SERS signal of polyvinylpyrrolidone will be generated, which will interfere with the SERS detection.

Contents of the invention

In order to solve the technical problems encountered in the above-mentioned prior art, the present invention provides a thin film composed of rough gold nanoparticles, its preparation method and application. The film composed of rough gold nanoparticles is composed of interconnected gold nanoparticles on a conductive substrate. The gold nanoparticles have many SERS hotspots and a uniform structure, which ensures the uniformity of the SERS signal and high detection sensitivity.

A thin film made of rough gold nanoparticles provided by the present invention includes many large gold nanoparticles on a conductive substrate and many small gold nanoparticles coated on the surface of the large gold nanoparticles. Large gold nanoparticles are stacked to form layers; the particle size of the small gold nanoparticles is 15-80nm, and the particle size of the large gold nanoparticles is 200-900nm. Due to the aggregation and coating of many small gold nanoparticles on the surface of large gold nanoparticles, the surface of large gold nanoparticles is rough and uneven, forming rough gold nanoparticles.

Simultaneously, in the present invention, the preparation method of the thin film that coarse gold nano particle is made of, it is that the gold seed crystal solution is evenly dispersed on the conductive substrate surface, then dries, and the gold seed crystal is evenly attached to the conductive substrate surface; Then, the adhered The conductive substrate of the gold seed crystal is used as the negative electrode, the rectangular graphite sheet is used as the anode, and the gold electrolyte is used as the electrolyte, and electrodeposition is carried out on the conductive substrate with the gold seed crystal attached to the surface, and then after post-treatment, the product is obtained. The conductive substrate described in the present invention is common, such as conductive glass (indium tin oxide (ITO) glass substrate), silicon wafer substrate, fluorine-doped tin dioxide conductive glass substrate, etc. can be used. The formation of the rough gold nanoparticle structure involved in the present invention is based on the growth of gold seed crystals on the conductive substrate into large gold nanoparticles, and then the electrodeposition of gold chloride in the solution to form small gold nanoparticles, small gold nanoparticles Particle aggregation coats large gold nanoparticles to form a rough structure.

In the above-mentioned preparation method, preferably, the gold seed crystal solution can be prepared by the following method: gold chloride tetrahydrate and polyvinylpyrrolidone (K29-32) are dissolved in deionized water to form a mixed solution, and then the hydrochloric acid is uniformly dispersed into the mixed solution, and then add sodium borohydride to reduce the gold ions to obtain a gold seed crystal solution; the size of the gold seed crystal is 5-15nm. More preferably, the gold seed crystal solution can be prepared by the following method: 1-5mg gold chloride tetrahydrate and 0.1-0.5g polyvinylpyrrolidone (K29-32) are completely dissolved in 20mL deionized water to form a mixed solution, and then 200μL of hydrochloric acid with a concentration of 20-30g/L is uniformly dispersed in the mixed solution, and then 1-5mg of sodium borohydride is added to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, which is placed in the cone Seal it in a shaped bottle and use it after standing for 24 hours.

In the above-mentioned preparation method, preferably, the configuration method of the gold electrolyte solution may be: firstly configure the gold chloride aqueous solution, and then add hydrochloric acid into the gold chloride aqueous solution to prepare the gold electrolyte solution. A more preferred gold electrolyte configuration method can be: 2-10mg of gold chloride tetrahydrate is completely dissolved in 15mL of deionized water to obtain an aqueous gold chloride solution, and then 200 μL of hydrochloric acid with a concentration of 20-30g/L is added to the chloride In the gold aqueous solution, the gold electrolyte is prepared.

In the above-mentioned preparation method, preferably, the gold seed crystal solution may be evenly covered on a 2-4 cm ² conductive substrate, and dried at 60-90° C. to form a gold seed crystal film.

In the above-mentioned preparation method, preferably, the post-treatment may include water washing, soaking, and drying. More preferably, it can be soaked in deionized water for 15-30 minutes after washing with deionized water. The function of soaking is to remove a very small amount of surfactant remaining in the gold seed crystal solution.

In addition, the inventors have found that the obtained thin film composed of rough gold nanoparticles can be used as an active substrate for surface-enhanced Raman scattering to detect organic dyes, for example, it can be used to detect trace dye rhodamine 6G.

Preferably, the excitation light of the laser Raman spectrometer has a wavelength of 532nm, a power of 0.1-2mW, and an integration time of 1-30s.

In the present invention, magnetron sputtering or ion sputtering are not used in the method for evenly attaching gold seed crystals on the surface of the conductive substrate, because the magnetron sputtering and ion sputtering methods rely on sputtering equipment, the cost is high, the method is complicated, and The gold film formed by magnetron sputtering and ion sputtering is finer and tighter, and a dense gold film will be formed after electrodeposition, and the coarse particles of the present invention cannot be produced or the rough particles produced are very few. In the invention, the gold seed crystal solution is evenly dispersed on the surface of the conductive substrate, and then dried.

The beneficial effect of the present invention compared with prior art is:

First, the thin film structure composed of rough gold nanoparticles in the present invention is formed by superposition and connection of several layers (2-4 layers) of gold nanoparticles with uneven surfaces. More gaps can provide numerous SERS hot spots, and this film structure has good structural uniformity, which provides a reliable guarantee for the uniformity of the SERS signal, so that the SERS sensitivity and signal uniformity of the target product are significantly improved. promote.

Its two, the gold electrolyte among the present invention is mainly made up of gold chloride tetrahydrate and hydrochloric acid, does not contain commonly used surfactants such as PVP, thus has guaranteed the cleanliness of the film surface that product gold nanoparticle is formed, in order to obtain pure to-be The SERS signal of the analyte molecule provides favorable conditions to avoid the interference of the SERS signal of the surfactant polyvinylpyrrolidone in the detection to the result.

Thirdly, using the prepared target product as the SERS active substrate, after conducting multiple and multi-batch tests on Rhodamine 6G at different concentrations, when the concentration of Rhodamine 6G is as low as 8×10 ^-9 mol/L When it is used, it can still be detected effectively, and the signal uniformity and repeatability of its detection are very good at any point on the target product and any point on different batches of products.

Fourth, the preparation method is scientific and effective. Evenly cover a layer of gold seed crystal solution film on the surface of the conductive substrate, and then electrodeposit to obtain a film formed by rough gold nanoparticles; and the formed film has multiple layers of rough gold nanoparticles, and finally not only produces high density, SERS hot spots The film formed by the controllable target product multilayer gold nanoparticles also makes it have higher SERS sensitivity, uniformity of structure and uniformity of signal, and it is more convenient to prepare large-area, high-density, structural The advantages of highly controllable parameters make the target product can be used as the active substrate of SERS to measure the trace organic matter attached to it.

Description of drawings

Fig. 1 is the result that the target product that makes uses scanning electron microscope (SEM) to characterize;

Fig. 2 is for the samples containing (a) 1×10 ^-6 mol/L, (b) 2×10 ^-7 mol/L, (c) 4×10 ^-8 mol/L, (d) 8×10 ^{- 9} mol One of the results of the characterization of the target product of rhodamine 6G/L using a co-concentration laser Raman spectrometer.

Detailed ways

The following examples are a further description of the content of the present invention as an explanation of the technical content of the present invention, but the essential content of the present invention is not limited to the following examples, those of ordinary skill in the art can and should know any Simple changes or replacements of the essential spirit of the invention shall fall within the scope of protection required by the present invention.

The preparation method of the material is to use plasma to bombard the conductive glass in an oxygen atmosphere to increase the hydrophilicity of its surface, and then uniformly attach a certain amount of gold seed crystal on the surface of the conductive substrate to make the gold seed crystal solution on the surface of the conductive glass Form a uniform film.

Example 1

In step 1, 80 μL of gold seed crystal solution was evenly added dropwise on the ITO conductive substrate to obtain a conductive glass covered with gold seed crystal solution, and then dried in an oven at 80°C to obtain a glass covered with a gold seed crystal solution film. Conductive substrate; the preparation method of the gold seed crystal solution is: 1mg gold chloride tetrahydrate and 0.1g polyvinylpyrrolidone (K29-32) are completely dissolved in 20mL deionized water to form a mixed solution, and then 200 μL of concentration is 20g/L Hydrochloric acid was uniformly dispersed in the mixed solution, and then 2 mg of sodium borohydride was added to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, which was sealed and left to stand for 24 hours before use.

Step 2, place the conductive glass covered with the gold seed crystal solution film prepared according to the above steps in the gold electrolyte, use the conductive glass with the gold seed crystal as the negative electrode, and the rectangular graphite sheet as the anode, and electrodeposit on the conductive glass Gold, 40°C electrolyte, 50μA cm ^-2 current, electrodeposition for 4 hours, to obtain a thin film composed of rough gold nanoparticles; wherein, the configuration method of the gold electrolyte is: completely dissolve 10mg of gold chloride tetrahydrate in 15mL A gold chloride aqueous solution was obtained in deionized water, and then 200 μL of hydrochloric acid with a concentration of 30 g/L was added into the gold chloride aqueous solution to obtain a gold electrolyte.

In step 3, the prepared thin film composed of rough gold nanoparticles was washed three times with deionized water, soaked for 20 minutes, and the product was cleaned and dried with argon to obtain the target product.

The target product obtained in Example 1 is characterized using a scanning electron microscope (SEM), and the results are as shown in Figure 1. The SEM image in Figure 1 shows that the target product is a thin film composed of rough gold nanoparticles, and many small gold nanoparticles aggregate Coating on the surface of large gold nanoparticles makes the surface rough and uneven to form rough gold nanoparticles. The film composed of rough gold nanoparticles is composed of several layers (about 2-4 layers) of uneven gold nanoparticles.

Use confocal laser Raman for the target products containing 1×10 ^-6 mol/L, 2×10 ^-7 mol/L, 4×10 ^-8 mol/L, 8×10 ^-9 mol/L Rhodamine 6G The spectrometer was used for characterization, and the results shown in Figure 2 were obtained, wherein the wavelength of the excitation light of the laser Raman spectrometer was 532nm, the power was 0.1-2mW, and the integration time was 1-30s. It can be seen from Figure 2 that the SERS activity of the prepared SERS substrate is very high, and rhodamine 6G with a detection concentration as low as 8×10 ^-9 mol/L can still obtain a strong SERS spectrum with prominent characteristic peaks.

Example 2

The concrete steps of preparation are:

In step 1, 100 μL of gold seed crystal solution was evenly added dropwise on the ITO conductive substrate to obtain a conductive glass covered with gold seed crystal solution, and then dried in an oven at 80°C to obtain a glass covered with a gold seed crystal solution film. conductive substrate;

Step 2, place the conductive glass covered with the gold seed crystal solution prepared by the above steps in the gold electrolyte, use the conductive glass with the gold seed crystal attached as the negative electrode, and the rectangular graphite sheet as the anode, and electrodeposit gold on the conductive glass , to obtain a thin film composed of rough gold nanoparticles; wherein, the configuration method of the gold electrolyte is: 8 mg of gold chloride tetrahydrate is completely dissolved in 15 mL of deionized water to obtain an aqueous gold chloride solution, and then 200 μL of hydrochloric acid with a concentration of 28 g/L Added to aqueous gold chloride solution to obtain gold electrolyte. The preparation method of the gold seed crystal solution is as follows: 2 mg of gold chloride tetrahydrate and 0.2 g of polyvinylpyrrolidone (K29-32) are completely dissolved in 20 mL of deionized water to form a mixed solution, and then 200 μL of hydrochloric acid with a concentration of 23 g/L is uniformly dispersed into the mixed solution, and then add 3 mg of sodium borohydride to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, which is sealed and left to stand for 24 hours before use.

In step 3, the prepared thin film composed of rough gold nanoparticles was washed three times with deionized water, soaked for 20 minutes, and the product was cleaned and dried with argon to obtain the target product.

The thin film composed of the above-mentioned rough gold nanoparticles is used as an active substrate for surface-enhanced Raman scattering, and a laser Raman spectrometer is used to measure the rhodamine 6G attached thereon, wherein the excitation light of the laser Raman spectrometer has a wavelength of 532nm and a power of 0.1-2mW, integration time 1-30s. When Rhodamine 6G was detected at a concentration of 8×10 ^-9 mol/L, the intensity of the characteristic peak at 614cm ^-1 was 125 counting units.

Example 3

The concrete steps of preparation are:

In step 1, 120 μL of gold seed crystal solution was evenly added dropwise on the ITO conductive substrate to obtain a conductive glass covered with gold seed crystal solution, and then dried in an oven at 80°C to obtain a glass covered with a gold seed crystal solution film. conductive substrate;

Step 2, place the conductive glass covered with the gold seed crystal solution prepared by the above steps in the gold electrolyte, use the conductive glass with the gold seed crystal attached as the negative electrode, and the rectangular graphite sheet as the anode, and electrodeposit gold on the conductive glass , to obtain a thin film composed of rough gold nanoparticles; wherein, the configuration method of the gold electrolyte is: 6 mg of gold chloride tetrahydrate is completely dissolved in 15 mL of deionized water to obtain an aqueous gold chloride solution, and then 200 μL of hydrochloric acid with a concentration of 25 g/L Added to aqueous gold chloride solution to obtain gold electrolyte. The preparation method of the gold seed solution is as follows: 3 mg of gold chloride tetrahydrate and 0.3 g of polyvinylpyrrolidone (K29-32) are completely dissolved in 20 mL of deionized water to form a mixed solution, and then 200 μL of hydrochloric acid with a concentration of 25 g/L is uniformly Disperse into the mixed solution, then add 4 mg of sodium borohydride to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, seal the gold seed crystal solution and let it stand for 24 hours before use.

Step 3, the film composed of rough gold nanoparticles is washed three times with deionized water, and soaked for 20 minutes. After the product is cleaned, it is dried with argon, and the rough gold nanoparticles shown in Figure 1 are obtained. composed of thin films.

The thin film composed of the above-mentioned rough gold nanoparticles is used as an active substrate for surface-enhanced Raman scattering, and a laser Raman spectrometer is used to measure the rhodamine 6G attached thereon, wherein the excitation light of the laser Raman spectrometer has a wavelength of 532nm and a power of 0.1-2mW, integration time 1-30s. When Rhodamine 6G was detected at a concentration of 4×10 ^-8 mol/L, the intensity of its characteristic peak at 614cm ^-1 was 459 counting units.

Example 4

In step 1, 110 μL of gold seed crystal solution was evenly added dropwise on the ITO conductive substrate to obtain conductive glass covered with gold seed crystal solution, and then dried in an oven at 80°C to obtain a glass covered with a gold seed crystal solution film. conductive substrate;

Step 2, place the conductive glass covered with the gold seed crystal solution prepared by the above steps in the gold electrolyte, use the conductive glass with the gold seed crystal attached as the negative electrode, and the rectangular graphite sheet as the anode, and electrodeposit gold on the conductive glass , to obtain a thin film composed of rough gold nanoparticles; wherein, the configuration method of the gold electrolyte is: 4 mg of gold chloride tetrahydrate is completely dissolved in 15 mL of deionized water to obtain an aqueous gold chloride solution, and then 200 μL of hydrochloric acid with a concentration of 23 g/L Added to aqueous gold chloride solution to obtain gold electrolyte. The preparation method of the gold seed solution is as follows: 4 mg of gold chloride tetrahydrate and 0.4 g of polyvinylpyrrolidone (K29-32) are completely dissolved in 20 mL of deionized water to form a mixed solution, and then 200 μL of hydrochloric acid with a concentration of 26 g/L is uniformly Disperse into the mixed solution, then add 4 mg of sodium borohydride to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, seal the gold seed crystal solution and let it stand for 24 hours before use.

In step 3, the prepared thin film composed of rough gold nanoparticles was washed three times with deionized water, soaked for 20 minutes, and the product was cleaned and dried with argon to obtain the target product.

The thin film composed of the above-mentioned rough gold nanoparticles is used as an active substrate for surface-enhanced Raman scattering, and a laser Raman spectrometer is used to measure the rhodamine 6G attached thereon, wherein the excitation light of the laser Raman spectrometer has a wavelength of 532nm and a power of 0.1-2mW, integration time 1-30s. When Rhodamine 6G was detected at a concentration of 2×10 ^-7 mol/L, the intensity of its characteristic peak at 614cm ^-1 was 714 counting units.

Example 5

In step 1, 120 μL of gold seed crystal solution was evenly added dropwise on the ITO conductive substrate to obtain a conductive glass covered with gold seed crystal solution, and then dried in an oven at 80°C to obtain a glass covered with a gold seed crystal solution film. conductive substrate;

Step 2, place the conductive glass covered with the gold seed crystal solution prepared by the above steps in the gold electrolyte, use the conductive glass with the gold seed crystal attached as the negative electrode, and the rectangular graphite sheet as the anode, and electrodeposit gold on the conductive glass , to obtain a thin film composed of rough gold nanoparticles; wherein, the configuration method of the gold electrolyte is: 2 mg of gold chloride tetrahydrate is completely dissolved in 15 mL of deionized water to obtain an aqueous gold chloride solution, and then 200 μL of hydrochloric acid with a concentration of 20 g/L Added to aqueous gold chloride solution to obtain gold electrolyte. The preparation method of the gold seed solution is as follows: 5 mg of gold chloride tetrahydrate and 0.5 g of polyvinylpyrrolidone (K29-32) are completely dissolved in 20 mL of deionized water to form a mixed solution, and then 200 μL of hydrochloric acid with a concentration of 30 g/L is uniformly Disperse into the mixed solution, then add 5 mg of sodium borohydride to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, seal the gold seed crystal solution and let it stand for 24 hours before use.

In step 3, the prepared thin film composed of rough gold nanoparticles was washed three times with deionized water, soaked for 20 minutes, and the product was cleaned and dried with argon to obtain the target product.

The thin film composed of the above-mentioned rough gold nanoparticles is used as an active substrate for surface-enhanced Raman scattering, and a laser Raman spectrometer is used to measure the rhodamine 6G attached thereon, wherein the excitation light of the laser Raman spectrometer has a wavelength of 532nm and a power of 0.1-2mW, integration time 1-30s. When Rhodamine 6G was detected at a concentration of 1×10 ^-6 mol/L, the intensity of its characteristic peak at 614cm ^-1 was 1143 counting units.

It should be noted that the above-mentioned technical content of the present invention is only an explanation and clarification to enable those skilled in the art to understand the technical essence of the present invention, so the described technical content is not intended to limit the scope of the present invention. . The substantive protection scope of the present invention should be defined by the claims. Those skilled in the art should know that any modification, equivalent replacement and improvement based on the essential spirit of the present invention shall fall within the scope of the essential protection of the present invention.

Claims (8)

1. A film made of rough gold nanoparticles, comprising numerous large gold nanoparticles on a conductive substrate and numerous small gold nanoparticles coated on the surface of the large gold nanoparticles, the numerous large gold nanoparticles The nanoparticles are stacked; the particle size of the small gold nanoparticles is 15-80nm, and the particle size of the large gold nanoparticles is 200-900nm; The preparation method of the thin film composed of rough gold nanoparticles comprises: uniformly dispersing the gold seed crystal solution on the surface of the conductive substrate, then drying, and uniformly attaching the gold seed crystal to the surface of the conductive substrate; then, attaching the gold seed crystal The conductive substrate is used as the negative electrode, the rectangular graphite sheet is used as the anode, and the gold electrolyte is used as the electrolyte, and the electrodeposition is carried out on the conductive substrate with the gold seed crystal attached to the surface, and then after post-treatment, to obtain final product; the gold electrolyte The configuration method is as follows: firstly configure the gold chloride aqueous solution, and then add hydrochloric acid into the gold chloride aqueous solution to prepare the gold electrolyte. 2. the thin film that rough gold nanoparticle is formed as claimed in claim 1, is characterized in that, described gold seed crystal solution adopts following method preparation: gold chloride tetrahydrate and polyvinylpyrrolidone are dissolved in deionized water to form mixed solution , and then uniformly disperse hydrochloric acid into the mixed solution, and then add sodium borohydride to reduce gold ions to obtain a gold seed crystal solution; the particle size of the gold seed crystal is 5-15nm. 3. The film made of rough gold nanoparticles according to claim 1, wherein the gold seed solution is evenly covered on a ^2-4cm conductive substrate, and dried into gold seeds at 60-90°C crystal film. 4. as claimed in claim 2, the film made of rough gold nanoparticles is characterized in that 1-5mg gold chloride tetrahydrate and 0.1-0.5g polyvinylpyrrolidone are completely dissolved in 20mL deionized water to form a mixed solution, and then 200μL of hydrochloric acid with a concentration of 20-30g/L is uniformly dispersed in the mixed solution, and then 1-5mg of sodium borohydride is added to the mixed solution to reduce the gold ions to obtain a gold seed crystal solution, which is placed in the cone Seal it in a shaped bottle and use it after standing for 24 hours. 5. the thin film that rough gold nanoparticle is formed as claimed in claim 1 is characterized in that, 2-10mg gold chloride tetrahydrate is completely dissolved in 15mL deionized water to obtain gold chloride aqueous solution, then 200 μ L concentration is 20-30g /L of hydrochloric acid was added to the gold chloride aqueous solution to prepare the gold electrolyte. 6. The thin film made of rough gold nanoparticles according to claim 1, wherein the post-treatment includes washing, soaking, and drying; after cleaning with deionized water, it needs to be soaked in deionized water for 15-30min. 7. The thin film made of rough gold nanoparticles according to claim 1 is used as an active substrate for surface-enhanced Raman scattering for detecting organic dyes. 8. application as claimed in claim 7, is characterized in that, described thin film is used as the active substrate of surface-enhanced Raman scattering for detecting the purposes of trace dye Rhodamine 6G.

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