Substrate for surface-enhanced raman scattering, method for preparing the substrate, and use thereof

Abstract

The present disclosure provides a substrate for surface-enhanced Raman scattering, comprising: a copper substrate; and a cuprous iodide passivation film formed on a surface of the copper substrate. The present disclosure also provides a preparation method of the substrate for surface-enhanced Raman scattering and a method of using the substrate for surface-enhanced Raman scattering.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of trace detection, and more particularly, to a substrate for surface-enhanced Raman scattering, a preparation method of the substrate, and a method of surface-enhanced Raman scattering using the substrate. BACKGROUND

[0002] The materials of surface-enhanced Raman scattering (SERS) substrates are generally metals and semiconductors, and traditional surface Raman enhancement substrates are mainly composed of noble metals such as gold and silver. Since the surface-enhanced Raman scattering substrates of noble metals are mostly expensive and easy to oxidize, this limits their practical application. In recent years, semiconductor nanostructures have been explored for their surface-enhanced Raman scattering activity, and many semiconductor materials have been proven to have Raman enhancement and can be used as SERS surface-enhanced Raman scattering substrates. For example, InAs / GaAs quantum dots, CuTe nanocrystals, Cu2O nanospheres, TiO2 nanostructures, etc. Compared with metal nanoparticles, semiconductor materials have high stability, structural diversity, good biocompatibility, low price, and fluorescence quenching performance.

[0003] In the process of implementing the present disclosure, the inventors have found at least the following problems in the prior art: Although many types of SERS substrates have been reported, they cannot meet the requirements of high sensitivity, stable performance, and low price at the same time. SUMMARY

[0004] Therefore, embodiments of the present disclosure provide a substrate for surface-enhanced Raman scattering, a preparation method of the substrate, and a method of surface-enhanced Raman scattering using the substrate.

[0005] According to an aspect of the present disclosure, a substrate for surface-enhanced Raman scattering is provided, which includes: a copper base; and a cuprous iodide passivation film formed on a surface of the copper base.

[0006] According to embodiments of the present disclosure, the copper base is made of pure copper or a copper alloy.

[0007] According to embodiments of the present disclosure, the copper base is prepared by a melting, rolling, or plating process.

[0008] According to embodiments of the present disclosure, the cuprous iodide passivation film is made of γ-CuI.

[0009] According to embodiments of the present disclosure, the cuprous iodide passivation film has a micro-nano structure with micro-nano particles having a size of 50-1000 nm.

[0010] According to embodiments of the present disclosure, the size of the micro-nano particles is 50-200 nm.

[0011] According to an embodiment of the present disclosure, the micro-nanoparticles include at least one of spherical particles, cuboid particles and ellipsoidal particles.

[0012] According to another aspect of the present disclosure, a method for preparing the substrate for surface-enhanced Raman scattering is provided, including the steps of: pretreating a copper substrate; and preparing a cuprous iodide passivation film on the surface of the pretreated copper substrate by using an electrochemical passivation method.

[0013] According to an embodiment of the present disclosure, the step of pretreating the copper substrate includes: cutting and polishing the copper substrate; and sequentially performing ultrasonic cleaning on the copper substrate with acetone, anhydrous ethanol and deionized water and blowing dry.

[0014] According to an embodiment of the present disclosure, the step of preparing a cuprous iodide passivation film on the surface of the pretreated copper substrate by using an electrochemical passivation method includes: adding an electrolyte into an electrolytic cell; and placing the pretreated copper substrate into the electrolytic cell for passivation, wherein the copper substrate serves as an anode.

[0015] According to an embodiment of the present disclosure, the electrolyte is an iodine ion solution.

[0016] According to an embodiment of the present disclosure, the concentration of iodine ions in the iodine ion solution is 10-200 mM.

[0017] According to an embodiment of the present disclosure, the iodine ion solution is a potassium iodide solution, a sodium iodide solution or a lithium iodide solution.

[0018] According to an embodiment of the present disclosure, in the step of placing the pretreated copper substrate into the electrolytic cell for passivation, a passivation voltage of 0.5-15 V is used and the passivation time is 10-600 s.

[0019] Another aspect of the present disclosure provides a method for surface-enhanced Raman scattering, including the steps of: dropping a solution to be tested onto the substrate or the substrate prepared by the method; and detecting by using a Raman spectrometer.

[0020] According to an embodiment of the present disclosure, in the step of detecting by using a Raman spectrometer, the wavelength of the Raman spectrometer includes 532 nm, 633 nm, 785 nm and 1064 nm.

[0021] From the above technical solutions, the substrate for surface-enhanced Raman scattering, the preparation method and the method for surface-enhanced Raman scattering provided by the present disclosure have the following beneficial effects:

[0022] 1. The substrate for surface-enhanced Raman scattering provided by the present disclosure, by forming a cuprous iodide passivation film on a copper substrate, a highly sensitive, stable and low-cost substrate for surface-enhanced Raman scattering is obtained, which takes a copper sheet or a copper alloy sheet as a substrate material, and a passivation film is prepared in an iodine ion-containing solution by an electrochemical method, and has good stability in air and aqueous solution, and good surface-enhanced Raman scattering performance, and can be stored in air for a long time (at least 6 months), and the surface-enhanced Raman performance remains stable. The substrate has no obvious impurity peak, and has the advantage of convenient test of characteristic peaks.

[0023] 2. The preparation method of the substrate for surface-enhanced Raman scattering provided by the present disclosure, which has simple preparation process, low cost, high SERS signal sensitivity, good repeatability, and is easy to popularize and mass produce and apply.

[0024] 3. The surface-enhanced Raman scattering method provided by the present disclosure, by using the substrate for surface-enhanced Raman scattering prepared by forming a cuprous iodide passivation film on a copper substrate, and using a Raman spectrometer for detection, trace detection can be realized quickly, with high sensitivity and high reliability, and the amount of sample required in the detection process is extremely small, suitable for various liquid samples, suitable for industrialized batch production, and can be applied to environmental pollutant detection, food safety detection, biological and medical technical fields. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0026] Figure 1 A flow chart of the preparation method of the substrate in the embodiment of the present disclosure is schematically shown;

[0027] Figure 2 A flow chart of the surface-enhanced Raman scattering method in the embodiment of the present disclosure is schematically shown;

[0028] Figure 3 A scanning electron microscope image of the substrate according to Embodiment 1 of the present disclosure is schematically shown;

[0029] Figure 4 An XRD spectrum of the passivation film of the substrate according to Embodiment 1 of the present disclosure is schematically shown;

[0030] Figure 5 A Raman spectrum of the substrate according to Embodiment 1 of the present disclosure for detecting methylene blue is schematically shown;

[0031] Figure 6 A Raman spectrum of the substrate according to Embodiment 1 of the present disclosure for detecting methylene blue of different concentrations is schematically shown;

[0032] Figure 7 Schematically shows a scanning electron microscope image of a white copper substrate according to Example 2 of the present disclosure;

[0033] Figure 8 Schematically shows a scanning electron microscope image of a beryllium copper substrate according to Example 2 of the present disclosure;

[0034] Figure 9 Schematically shows the Raman spectrum of methylene blue detected by the substrate according to Example 2 of the present disclosure;

[0035] Figure 10 Schematically shows a scanning electron microscope image of a substrate of a silver-copper alloy substrate containing 5% silver according to Example 3 of the present disclosure;

[0036] Figure 11 Schematically shows the Raman spectrum of methylene blue detected by the substrate according to Example 3 of the present disclosure;

[0037] Figure 12 The Raman spectra of methylene blue detected on a pure copper substrate and a substrate including a cuprous iodide passivation film according to Comparative Example 1 of the present disclosure are schematically shown. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0039] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0040] In the case of using expressions such as "at least one of A, B or C", it will be generally understood that the expression is intended to mean any of the natural inclusive permutations. For example, "A or B or C" will cover the cases of: "A" alone, "B" alone, "C" alone, "A and B" together, "A and C" together, "B and C" together, and "A and B and C" together, as well as any other of the possible combinations under these terms. The terms "first", "second", "third", "fourth", "fifth" and the like in the description and in the claims, if any, are used for describing various embodiments and are not necessarily used consistently in all embodiments. They are generally used for the purpose of distinction among various elements and are not intended to convey any meaning of priority or chronological order. Thus, a feature specified as "first" can imply that the feature is one of the first elements to be performed, or it can imply that the feature is the first element performed, irrespective of other elements performed before it. The same applies to the terms "second", "third", "fourth", "fifth" and the like.

[0041] Surface enhanced Raman scattering (SERS) is a technique for detecting molecular vibration spectrum, and its enhancement principle mainly includes electromagnetic enhancement mechanism and chemical enhancement mechanism. The former is mainly related to SERS metal substrate, and is derived from collective excitation of metal surface delocalized electrons, i.e. surface plasmon resonance effect. The latter is mainly derived from charge transfer, i.e. under excitation light of suitable energy, charge transfer from substrate to molecule or from molecule to substrate can be generated, so that the Raman signal of surface adsorbed molecules is significantly enhanced.

[0042] The material of a surface enhanced Raman scattering (SERS) substrate is generally metal and semiconductor, and a traditional surface Raman enhancement substrate is mainly composed of noble metals such as gold and silver. Since the surface enhanced Raman scattering substrate of noble metal is mostly expensive and easy to be oxidized, it limits its practical application. In recent years, semiconductor nanostructures have been explored due to their surface enhanced Raman scattering activity, and many semiconductor materials have been proved to have Raman enhancement effect and can be used as SERS surface enhanced Raman scattering substrate. For example, InAs / GaAs quantum dots, CuTe nanocrystals, Cu2O nanospheres, TiO2 nanostructures, etc. Compared with metal nanoparticles, semiconductor materials have high stability, structural diversity, good biocompatibility, low price and fluorescence quenching performance.

[0043] So far, although many types of surface enhanced Raman scattering substrates have been reported, they cannot meet the requirements of high sensitivity, stable performance and low price at the same time.

[0044] Cuprous iodide (CuI) is a non-aqueous crystal, which has α, β and γ three crystal phases, wherein the α crystal phase exists above 405°C, the β crystal phase exists at 369-405°C, and the γ crystal phase exists below 369°C. The α crystal phase has a cubic structure, and is a crystal with Cu +It is mainly a mixed conductor with charge. The β crystal phase has a hexagonal crystal structure and is a superionic conductor. The γ crystal phase has a zinc blende structure and is a P-type wide bandgap semiconductor material with a bandgap width of 3.leV. It has a very high exciton binding energy (62meV). At the same time, γ-CuI has a small hole effective mass and a high hole mobility. In addition, γ-CuI has the advantages of being non-toxic, abundant in reserves, and low in cost. γ-CuI thin films have a high carrier concentration, hole mobility, and low resistivity. The traditional preparation methods of γ-CuI thin films mainly include copper film iodination method, vacuum thermal evaporation technology, and electrochemical preparation method. The copper film iodination method involves iodinating the copper film with an ethanol solution of iodine to prepare a highly transparent and conductive γ-CuI thin film. The vacuum thermal evaporation technology uses CuI powder as the evaporation source to deposit a γ-CuI thin film on a silicon wafer substrate. The electrochemical preparation method uses copper nitrate and potassium iodide as main salts to prepare the electroplating solution, and electro-deposits β-CuI and γ-CuI films on the surface of silicon wafers.

[0045] The above three methods have problems such as complex processes and environmental pollution in the production process.

[0046] Embodiments of the present disclosure provide a substrate for surface-enhanced Raman scattering, comprising: a copper substrate; and a cuprous iodide passivation film formed on the surface of the copper substrate. The copper substrate is a substrate whose chemical composition includes copper, and can be, for example, pure copper or a copper alloy. Any substrate chemically containing copper can be used, and the embodiments of the present disclosure are not limited thereto.

[0047] In the embodiments of the present disclosure, the copper substrate is made of pure copper or a copper alloy. The copper alloy may include non-precious copper alloys and precious copper alloys. The precious metal is gold or silver. The non-precious copper alloys include red copper, chromium-zirconium copper, brass, white copper, beryllium copper, and phosphor copper. The precious copper alloys include alloys formed by gold or silver and copper.

[0048] In the embodiments of the present disclosure, the copper substrate is prepared by smelting, rolling or plating processes. Any common process for preparing a copper substrate can be used, and the embodiments of the present disclosure do not limit this.

[0049] In the embodiments of the present disclosure, the cuprous iodide passivation film adopts γ-CuI. It should be noted that, under the preparation conditions of the embodiments of the present disclosure, the main component of the cuprous iodide passivation film is γ-CuI. Since the γ crystal phase exists below 369°C, the requirements for the preparation temperature are reduced.

[0050] In the embodiments of the present disclosure, the cuprous iodide passivation film adopts a micro-nano structure, the micro-nano structure has micro-nano particles with a size of 50-1000 nm, the micro-nano particles are nano or micron-sized particles, wherein the cuprous iodide passivation film of the embodiments of the present disclosure mainly consists of γ-CuI, the morphology of the γ-CuI is micro-nano particles, and the structure of the micro-nano particles enables the substrate to have the effect of surface-enhanced Raman scattering.

[0051] In the embodiments of the present disclosure, the size of the micro-nano particles is 50-200 nm, and when the size of the micro-nano particles of the cuprous iodide passivation film is 50-200 nm, the enhancement effect of Raman is the best.

[0052] In the embodiments of the present disclosure, the micro-nano particles include at least one of spherical particles, cuboid particles and ellipsoidal particles. In the process of forming the cuprous iodide passivation film, different micro-nano particles with different morphologies can be formed according to different conditions, including spherical, cuboid and ellipsoidal particles, and other three-dimensional micro-nano particle shapes, and the micro-nano particles with these shapes all have the effect of surface-enhanced Raman, and any shape having the effect of surface-enhanced Raman can be used, and the embodiments of the present disclosure are not limited in this regard.

[0053] Figure 1 A flow chart of a preparation method of a substrate in the embodiments of the present disclosure is schematically shown.

[0054] The embodiments of the present disclosure provide a preparation method of the above-mentioned substrate for surface-enhanced Raman scattering, as shown in Figure 1 The preparation method includes the following steps:

[0055] Step S1: pretreating the copper substrate;

[0056] In the embodiments of the present disclosure, the step of pretreating the copper substrate includes: cutting and polishing the copper substrate, and sequentially ultrasonic cleaning and blowing dry the copper substrate with acetone, anhydrous ethanol and deionized water. Specifically, the copper substrate (thickness 0.01 mm-1.00 mm) can be cut into a size of 1-10 cm x 1-10 cm, polished with sandpaper, and then sequentially ultrasonic cleaned and blown dry with acetone, anhydrous ethanol and deionized water for 10 min.

[0057] Step S2: preparing a cuprous iodide passivation film on the surface of the pretreated copper substrate by an electrochemical passivation method.

[0058] In the embodiment of the present disclosure, the step of preparing the cuprous iodide passivation film on the surface of the pretreated copper substrate by the electrochemical passivation method comprises: adding an electrolyte into an electrolytic cell; and placing the pretreated copper substrate into the electrolytic cell for passivation, wherein the copper substrate serves as an anode, and a cathode can be a platinum electrode or other electrode, and any electrode that can conduct electricity can be used, and the embodiment of the present disclosure does not limit this. In addition, according to actual needs, when a three-electrode method is used, a calomel electrode can be used as a reference electrode.

[0059] In the embodiment of the present disclosure, the electrolyte is an iodine ion solution, and any solution containing iodine ions can be used, and the embodiment of the present disclosure does not limit this.

[0060] In the embodiment of the present disclosure, the concentration of iodine ions in the iodine ion solution is 10-200 mM. When the concentration of iodine ions is too large or too small, the size of the micro-nanoparticles of the cuprous iodide passivation film will be affected, resulting in no surface Raman enhancement effect, and therefore the concentration of iodine ions is set to 10-200 mM.

[0061] In the embodiment of the present disclosure, the iodine ion solution is a potassium iodide solution or a sodium iodide solution, and in addition, lithium iodide and the like are also included, and any solution containing iodine ions can be used, and the embodiment of the present disclosure does not limit this.

[0062] In the embodiment of the present disclosure, in the step of placing the pretreated copper substrate into the electrolytic cell for passivation, the passivation voltage used is 0.5-15 V, and the passivation time is 10-600 s. The passivation voltage and the passivation time will affect the thickness of the passivation film. If the passivation time is too long or the passivation voltage is too large, the passivation film will be too thick and will easily fall off. If the passivation time is too short or the passivation voltage is too small, the passivation film will be too thin and will not have a surface Raman enhancement effect. Therefore, the passivation voltage is set to 0.5-15 V, and the passivation time is set to 10-600 s.

[0063] Figure 2 A flowchart of a surface-enhanced Raman scattering method in the embodiment of the present disclosure is schematically shown.

[0064] The embodiment of the present disclosure provides a surface-enhanced Raman scattering method, as shown in Figure 2 The method comprises the following steps:

[0065] Step S3: dropping the to-be-tested solution onto the substrate or the substrate prepared by the method.

[0066] Step S4: detecting by using a Raman spectrometer.

[0067] In the embodiments of the present disclosure, the wavelength of the Raman spectrometer in the step of detecting by using the Raman spectrometer includes 532 nm, 633 nm, 785 nm and 1064 nm.

[0068] The embodiments of the present disclosure form a dense cuprous iodide passivation film on a copper substrate by an electrochemical passivation method, and obtain a highly sensitive, stable and low-cost substrate for surface-enhanced Raman scattering, while the preparation process is simple, low in cost, easy to popularize and mass-produce. In addition, the preparation process is non-toxic and non-polluting, the prepared substrate is non-water-soluble, and can be stored for a long time under light-proof conditions, effectively improving the stability and long-term use performance of the Raman substrate.

[0069] The substrate of the embodiments of the present disclosure will be described in detail below in combination with examples and related experiments.

[0070] Example 1

[0071] (1) The pure copper substrate (thickness 1.00 mm) was cut into a size of 10 cm x 10 cm, polished with sandpaper, and then ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 10 min and dried;

[0072] (2) The pretreated copper substrate material was placed in an electrolytic cell, and a cuprous iodide passivation film was prepared by an electrochemical passivation method, wherein the electrochemical passivation adopted a three-electrode mode, the reference electrode was a mercury-mercury electrode, the electrolyte was a 200 mM KI solution, the passivation voltage was 15 V vs SCE, and the passivation time was 10 s;

[0073] (3) The substrate with the cuprous iodide passivation film was taken out, washed with deionized water and dried, the substrate was cut into 0.5 cm x 0.5 cm, and surface analysis was performed, wherein the scanning electron microscope image of the prepared substrate is shown in FIG. 1, and it can be seen that the cuprous iodide passivation film on the surface of the substrate has good compactness, and the particle size is about 100 nm, Figure 3 Figure 4 The XRD pattern of the passivation film of the substrate according to Example 1 of the present disclosure is schematically shown in FIG. 2, and it can be seen that the phase of the prepared cuprous iodide passivation film is γ-CuI; Figure 4

[0074] (4) The 1 ppm methylene blue (MB) solution was detected by using a Zhuli Han Guan benchtop Raman instrument (laser wavelength: 638 nm) and a HORIBA benchtop Raman instrument (laser wavelength: 532 / 633 / 638 / 785 nm), and it can be seen from FIG. 3 that the substrate has surface-enhanced Raman scattering performance, and the peak positions of the Raman spectra appearing in curves 1-4 are all characteristic peaks of methylene blue; Figure 5

[0075] ​​​(5) The Zhuoli Hanguang tabletop Raman spectroscopy was used to detect MB solutions of different concentrations (test parameters: integration time 15s, laser power 30mW, laser wavelength 638nm). Figure 6 To detect the Raman spectra of MB at different concentrations, Figure 6 It can be seen that the Zhuoli Hanguang desktop Raman instrument can detect MB solution with a concentration of 0.1ppm (curve 4) and has rapid detection performance.

[0076] Example 2

[0077] (1) A non-precious copper alloy substrate (thickness 0.01 mm) was cut into a size of 1 cm × 1 cm, polished with sandpaper, and ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 10 min and blown dry. The non-precious copper alloys include red copper, chromium zirconium copper, brass, white copper, beryllium copper, and phosphor copper.

[0078] (2) The pretreated copper substrate material was placed in an electrolytic cell, and a cuprous iodide passivation film was prepared by electrochemical passivation. The electrochemical passivation adopted a three-electrode mode, the reference electrode was a calomel electrode, the electrolyte was a 10 mM NaI solution, the passivation voltage was 0.5 V vs SCE, and the passivation time was 600 s.

[0079] (3) The substrate with the cuprous iodide passivation film formed thereon was taken out, rinsed with deionized water, and then blown dry. The substrate was cut into pieces of 0.5 cm × 0.5 cm. Figure 7 The scanning electron microscope image of the substrate with a white copper base is as follows: Figure 7 As shown, it can be seen that the cuprous iodide passivation film on the substrate surface has good density and the particle size is 100-400nm. Figure 8 The scanning electron microscope image of the substrate with beryllium copper base is as follows: Figure 8 As shown, the particle size of the cuprous iodide passivation film on the substrate surface is 50-200 nm.

[0080] (4) A Zhuoli Hanguang tabletop Raman spectroscopy was used to detect 1 ppm MB solution (test parameters: integration time 15 s, laser power 30 mW, laser wavelength 638 nm). Figure 9 MB Raman spectra were detected for different non-precious copper alloy substrates. Figure 9 It can be seen that different non-precious metal copper alloy substrates all have Raman enhancement effects, and the peaks of the Raman spectra that appear are all characteristic peaks of methylene blue.

[0081] Example 3

[0082] (1) The noble metal copper alloy substrate (thickness 0.1 mm) was cut into a size of 5 cm x 5 cm, polished with sandpaper, and then ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 10 min and dried, wherein the noble metal copper alloy included silver copper alloy, including silver copper alloy with copper content of 5% and 15%.

[0083] (2) The pretreated copper substrate material was placed in an electrolytic cell, and a cuprous iodide passivation film was prepared by an electrochemical passivation method, wherein the electrochemical passivation adopted a three-electrode mode, the reference electrode was a mercury-mercury electrode, the electrolyte was a 100 mM LiI solution, the passivation voltage was 5 V vs SCE, and the passivation time was 100 s.

[0084] (3) The substrate with the formed cuprous iodide passivation film was taken out, rinsed with deionized water and dried, and the substrate was cut into 0.5 cm x 0.5 cm, Figure 10 The scanning electron microscope image of the substrate of the silver copper alloy substrate with a silver content of 5% is shown in Figure 10 , and it can be seen that the cuprous iodide passivation film on the surface of the substrate has good compactness, and the particle size is 500-1000 nm.

[0085] (4) The Raman spectrum of 1 ppm MB solution was detected by using a ZOLI HanGuang benchtop Raman instrument (test parameters: integration time 15 s, laser power 30 mW, laser wavelength 638 nm), Figure 11 The Raman spectrum of different noble metal copper alloy substrates for detecting MB is shown in Figure 11 , and it can be seen that different noble metal copper alloy substrates have Raman enhancement effect, and the peak position of the Raman spectrum appears as the characteristic peak of methylene blue.

[0086] Comparative Example 1

[0087] The Raman spectrum of pure copper substrate and 1 ppm methylene blue (MB) solution was detected by using a ZOLI HanGuang benchtop Raman instrument (test parameters: integration time 15 s, laser power 30 mW, laser wavelength 638 nm) using pure copper substrate as a substrate. The results are shown in Figure 12 .

[0088] The substrate including the cuprous iodide passivation film prepared according to the above method was stored in air and light for six months, and the Raman spectrum of the substrate was detected by using a ZOLI HanGuang benchtop Raman instrument, and the Raman spectrum of 1 ppm methylene blue (MB) solution was detected by using the substrate (test parameters: integration time 15 s, laser power 30 mW, laser wavelength 638 nm). The results are shown in Figure 12 .

[0089] It can be seen from Figure 12 that the pure copper substrate (curve 4) and the substrate including the cuprous iodide passivation film (curve 3) do not have characteristic peaks, indicating that the substrate does not affect the resolution of the characteristic peaks of the sample to be tested.

[0090] As shown in FIG. 2, when detecting 1 ppm methylene blue (MB) solution, no characteristic peaks of methylene blue appeared (curve 2) on the pure copper substrate without surface Raman enhancement effect, while the characteristic peaks of methylene blue appeared (curve 1) on the substrate including the cuprous iodide passivation film, indicating that the cuprous iodide passivation film has a surface-enhanced Raman scattering effect, and the corresponding substrate can be used in surface-enhanced Raman scattering.

[0091] As can be seen from the above examples and comparative examples, the cuprous iodide passivation film surface-enhanced Raman scattering substrate of the embodiments of the present disclosure has good surface-enhanced Raman scattering performance, can be stored in air for a long time (at least 6 months), and the surface-enhanced Raman performance remains stable. The substrate has no obvious impurity peaks, and has the advantage of convenient test peak resolution. At the same time, the preparation process is simple, the amount of sample needed in the detection process is extremely small, it is suitable for various liquid samples, and can be applied to environmental pollutant detection, food safety detection, biological and medical fields, and has wide application prospects in industrialized batch production and rapid detection of trace organic substances.

[0092] It can be understood by those skilled in the art that the features described in various embodiments and / or claims of the present disclosure can be combined and / or integrated in various combinations, even if such combinations or integrations are not explicitly described in the present disclosure. In particular, the features described in various embodiments and / or claims of the present disclosure can be combined and / or integrated in various combinations without departing from the spirit and teachings of the present disclosure. All these combinations and / or integrations fall within the scope of the present disclosure.

[0093] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present disclosure. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A substrate for surface enhanced Raman scattering, characterized in that: The substrate comprises: copper substrate; and The cuprous iodide passivation film is formed on the surface of the copper substrate based on an electrochemical passivation method. The cuprous iodide passivation film adopts a micro-nano structure with a surface enhanced Raman effect.

2. The substrate according to claim 1, wherein The copper substrate is made of pure copper or copper alloy.

3. The substrate according to claim 2, wherein The copper matrix is ​​prepared by smelting, rolling or plating technology.

4. The substrate according to claim 1, wherein The cuprous iodide passivation film is made of γ-CuI.

5. The substrate according to claim 4, characterized in that The micro-nano structure has micro-nano particles with a size of 50-1000 nm.

6. The substrate according to claim 5, characterized in that The size of the micro-nano particles is 50-200 nm.

7. The substrate according to claim 5, characterized in that The micro-nano particles include at least one of spherical particles, cuboid particles and pyramidal particles.

8. A method for preparing a substrate according to any one of claims 1 to 7, characterized in that: The steps include: Pre-treating the copper substrate; and The cuprous iodide passivation film was prepared on the surface of the pretreated copper substrate by electrochemical passivation.

9. The method according to claim 8, characterized in that The step of pre-treating the copper substrate comprises: The copper substrate was cut and polished, and ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water in sequence and then dried.

10. The method according to claim 8, characterized in that The step of preparing a cuprous iodide passivation film on the surface of a pretreated copper substrate by an electrochemical passivation method comprises: adding electrolyte to the electrolytic cell; and The pretreated copper substrate is placed in the electrolytic cell for passivation, wherein the copper substrate serves as an anode.

11. The method according to claim 10, characterized in that The electrolyte is an iodide ion solution.

12. The method according to claim 11, characterized in that The concentration of iodide ions in the iodide ion solution is 10-200 mM.

13. The method according to claim 11, characterized in that The iodide ion solution is potassium iodide solution, sodium iodide solution or lithium iodide solution.

14. The method according to claim 10, characterized in that In the step of placing the pretreated copper substrate into the electrolytic cell for passivation, the passivation voltage used is 0.5-15V and the passivation time is 10-600s.

15. A surface enhanced Raman scattering method, characterized in that: The steps include: Adding the solution to be tested dropwise onto the substrate according to any one of claims 1 to 7 or the substrate prepared by the method according to any one of claims 8 to 14; and The results were detected by Raman spectrometer.

16. The method according to claim 15, characterized in that In the step of detecting by using a Raman spectrometer, the wavelength of the Raman spectrometer includes 532nm, 633nm, 785nm and 1064nm.

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