Surface-enhanced Raman substrate as well as preparation method and application thereof

Abstract

The invention relates to a surface-enhanced Raman substrate, and belongs to the technical field of surface Raman scattering detection. The surface-enhanced Raman substrate comprises a first enhanced signal layer, a core layer and a second enhanced signal layer which are sequentially stacked, the first enhanced signal layer comprises a two-dimensional material A, the core layer comprises molecules to be detected, the second enhanced signal layer comprises a two-dimensional material B, and the two-dimensional material A and the two-dimensional material B are mutually independent. The molecules to be detected are arranged in the interlayer of the first enhanced signal layer and the second enhanced signal layer which comprise the two-dimensional materials, so that the two-dimensional materials are arranged on the two sides of the molecules to be detected, the chemical action strength of the molecules to be detected and the two-dimensional materials can be improved, and the chemical mechanism effect of SERS of the two-dimensional materials is further enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface Raman scattering detection, and relates to a surface-enhanced Raman substrate, a preparation method thereof, and an application thereof. Background Art

[0002] Surface-enhanced Raman scattering (SERS) detection can achieve rapid and non-destructive detection of the structural type and concentration of molecules by enhancing the Raman scattering intensity of molecules and measuring their Raman scattering spectra, and has important application prospects in environmental monitoring, biomedicine, disease detection, food safety analysis, etc.

[0003] SERS requires the use of specific substrates to enhance the Raman scattering intensity of molecules, so as to achieve highly sensitive detection. Commonly used SERS substrate materials include rough surfaces or nanoparticles composed of noble metals (such as gold, silver, copper), which enhance Raman signals through electromagnetic enhancement mechanisms or chemical enhancement mechanisms, and can achieve Raman signal enhancement effects up to 10 8 times. However, the direct contact between the molecules to be detected and the substrate will cause problems such as molecular bond deformation, peak position drift, photocatalytic reaction, carbonization, etc., resulting in unstable signals and poor repeatability, thereby increasing the difficulty of quantitative analysis, and there is an urgent need for improvement. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a substrate that can significantly improve the enhancement effect of surface-enhanced Raman scattering (SERS) while improving the detection stability. The present invention also provides a preparation method of the above substrate, and an application of the above substrate in surface Raman scattering detection.

[0005] The technical solution of the present invention is as follows:

[0006] A surface-enhanced Raman substrate includes a first enhanced signal layer, a core layer, and a second enhanced signal layer that are sequentially stacked. The first enhanced signal layer includes two-dimensional material A, the core layer includes molecules to be detected, the second enhanced signal layer includes two-dimensional material B, and the two-dimensional material A and the two-dimensional material B are independent of each other.

[0007] In some embodiments, the two-dimensional material A and the two-dimensional material B are independently selected from one of graphene, boron nitride, black phosphorus, GaTe, MXene, and transition metal chalcogenides.

[0008] In some embodiments, the two-dimensional material A and the two-dimensional material B are each independently selected from one of monolayer materials, multilayer homogeneous materials, and multilayer heterogeneous materials.

[0009] In some of these embodiments, a first substrate is further included, and the first substrate is stacked on the first enhanced signal layer in a direction away from the core layer; and / or, the surface-enhanced Raman substrate further includes a second substrate, and the second substrate is stacked on the second enhanced signal layer in a direction away from the core layer.

[0010] In some of these embodiments, each of the first substrate and the second substrate independently includes one or more of a silicon wafer, a quartz wafer, a sapphire, and PDMS.

[0011] In some of these embodiments, a first metal layer is further included, and the first metal layer is stacked on the first enhanced signal layer in a direction close to the core layer; and / or, the surface-enhanced Raman substrate further includes a second metal layer, and the second metal layer is stacked on the second enhanced signal layer in a direction close to the core layer.

[0012] In some of these embodiments, the first metal layer has one or more of a micro-nano structure or a rough surface; and / or, the second metal layer has one or more of a micro-nano structure or a rough surface.

[0013] In some of these embodiments, the metal in each of the first metal layer and the second metal layer is independently selected from one or more of Au, Ag, and Cu.

[0014] A method for preparing the above surface-enhanced Raman substrate includes the following steps:

[0015] Take two-dimensional material A and prepare a first enhanced signal layer;

[0016] Place the molecule to be detected on the first enhanced signal layer to prepare a core layer;

[0017] Take two-dimensional material B and prepare a second enhanced signal layer;

[0018] Place the second enhanced signal layer on the core layer.

[0019] The present invention also provides an application of the above surface-enhanced Raman substrate or the surface-enhanced Raman substrate prepared by the above preparation method in surface Raman scattering detection.

[0020] The beneficial effects of the present invention are as follows:

[0021] In the present invention, the molecule to be detected is disposed in the middle of the sandwich of the first enhanced signal layer and the second enhanced signal layer including two-dimensional materials, so that there are two-dimensional materials on both sides of the molecule to be detected, thereby improving the chemical interaction intensity between the molecule to be detected and the two-dimensional materials and realizing further enhancement of the chemical mechanism of two-dimensional material SERS;

[0022] The sandwich structure of the present invention also helps to isolate the molecules to be detected, avoiding direct contact between the molecules to be detected and the external environment (such as oxygen, water vapor, etc.) and the metal surface, thus preventing chemical reactions such as oxidation reactions and photocatalytic reactions, reducing background interference, improving detection stability, and ensuring the repeatability of detection results.

[0023] Other advantages, objects, and features of the present invention will be described to some extent in the following specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objects and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the objects, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0025] Figure 1 is a sandwich structure substrate composed of single-layer two-dimensional materials. Among them, (a) represents a sandwich structure composed of 2 single-layer MoS 2 sandwiching the molecules to be detected; (b) represents a sandwich structure composed of 2 single-layer graphene sandwiching the molecules to be detected; (c) represents a sandwich structure composed of MoS 2 and a single layer of graphene sandwiching the molecules to be detected.

[0026] Figure 2 is a sandwich structure substrate composed of multi-layer homogeneous materials and multi-layer heterogeneous materials. Among them, (a) represents a sandwich structure composed of 3 layers of MoS 2 and 2 layers of MoS 2 sandwiching the molecules to be detected; the two-dimensional materials in (b) are 2 layers of MoS 2 , and a 2-layer heterostructure composed of MoS 2 and graphene; the two-dimensional materials in (c) are 2-layer heterostructures composed of MoS 2 and graphene, and 2-layer heterostructures composed of WSe 2 and graphene.

[0027] Figure 3 is a sandwich structure composed of two single-layer MoS 2 sandwiching the molecules to be detected placed on a SiO 2 / Si substrate.

[0028] Figure 4 is that 2 single-layer MoS 2 are respectively placed on a SiO 2 / Si substrate coated with a thin layer of gold and a PDMS substrate coated with a thin layer of gold, and the molecules to be detected are located between the 2 single-layer MoS 2 .

[0029] Figure 5 There are two single-layer MoS 2 which are respectively placed on an SiO 2 / Si substrate coated with a thin layer of gold and a PDMS substrate coated with a thin layer of gold. The molecule to be detected is located between the two single-layer MoS 2 , and the thin layer of gold has a rough surface.

[0030] Figure 6 This is an optical microscope photograph of WSe 2 / CuPc / WSe 2 / SiO 2 / Si in Example 1.

[0031] Figure 7 This is a schematic diagram of the structure of MoS 2 / CuPc / MoS 2 in Example 2 and the results of the surface-enhanced Raman scattering enhancement factor obtained by theoretical calculation. Among them, Figure 7 in (a) is the schematic diagram of the structure of MoS 2 / CuPc / MoS 2 , Figure 7 and in (b) are the results of the theoretical calculation of the surface-enhanced Raman scattering enhancement factor.

[0032] Figure 8 This is a schematic diagram of the structure of MoS 2 / CuPc / graphene in Example 3 and the results of the surface-enhanced Raman scattering enhancement factor obtained by theoretical calculation. Among them, Figure 8 in (a) is the schematic diagram of the structure of MoS 2 / CuPc / graphene, Figure 8 and in (b) are the results of the theoretical calculation of the surface-enhanced Raman scattering enhancement factor.

[0033] Figure 9 This is an optical microscope photograph of CuPc / WSe 2 / SiO 2 / Si in Comparative Example 1.

[0034] Figure 10 This is a comparative diagram of the surface-enhanced Raman scattering detection spectra of Example 1 and Comparative Example 1. Specific embodiments

[0035] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0036] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation on the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0037] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "center", "horizontal", "longitudinal", "length", "width", "thickness", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicating the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] When describing the positional relationship, unless otherwise specified, when an element such as a layer, film or substrate is referred to as being "on" another film layer, it can be directly on the other film layer or there can also be an intermediate film layer. Further, when a layer is referred to as being "under" another layer, it can be directly below or there can be one or more intermediate layers. It can also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or there can also be one or more intermediate layers.

[0039] When using the terms "including", "having", and "comprising" described in this article, it is intended to cover non-exclusive inclusion. Unless a clear limiting term is used, such as "only", "consisting of", etc., another component can also be added.

[0040] In the present invention, "at least one" refers to any one, any two, or any two or more. "Multiple" refers to more than two. Unless otherwise mentioned, a term in the singular form may include the plural form and should not be construed as having a quantity of one.

[0041] Currently, in SERS detection based on two-dimensional materials, the molecule to be detected is only adsorbed on the surface of the two-dimensional material, and there is only two-dimensional material on one side of the molecule. Through the interaction between the molecule and the surface of the two-dimensional material, the enhancement of Raman scattering intensity is achieved based on chemical mechanisms such as charge transfer and resonance transition. Whether it is a single-layer or multi-layer homogeneous or heterogeneous two-dimensional material, the chemical enhancement effect mainly depends on the properties of the outermost material, which reflects the short-range chemical interaction characteristics of two-dimensional material SERS. Therefore, the enhancement effect of current SERS detection based on two-dimensional materials is usually between 10 and 100 times, the Raman enhancement effect is weak, and to achieve an ideal enhancement effect, the excitation light wavelength needs to be selected within a specific range, and the excitation light wavelength range is narrow.

[0042] Based on this, the present invention proposes to place the molecule to be detected in the middle of the sandwich of two layers of two-dimensional materials, so that there is two-dimensional material on both sides of the molecule to be detected, thereby increasing the intensity of the chemical interaction between the molecule to be detected and the two-dimensional material, and further enhancing the chemical mechanism of two-dimensional material SERS.

[0043] The technical solution of the present invention is as follows:

[0044] A surface-enhanced Raman substrate, comprising a first enhanced signal layer, a core layer, and a second enhanced signal layer stacked in sequence. The first enhanced signal layer comprises two-dimensional material A, the core layer comprises the molecule to be detected, the second enhanced signal layer comprises two-dimensional material B, and the two-dimensional material A and the two-dimensional material B are independent of each other.

[0045] The present invention places the molecule to be detected in the middle of the sandwich of the first enhanced signal layer and the second enhanced signal layer comprising two-dimensional materials, so that there is two-dimensional material on both sides of the molecule to be detected, thereby increasing the intensity of the chemical interaction between the molecule to be detected and the two-dimensional material, and further enhancing the chemical mechanism of two-dimensional material SERS. The sandwich structure of the present invention also helps to isolate the molecule to be detected, avoiding chemical reactions such as oxidation reactions and photocatalytic reactions that occur when the molecule to be detected directly contacts the external environment (such as oxygen, water vapor, etc.) and the metal surface, thereby reducing background interference, improving detection stability, and ensuring the repeatability of detection results.

[0046] The two-dimensional materials of the present invention can be any materials formed by van der Waals interactions; in some specific examples, the two-dimensional material A and the two-dimensional material B are each independently selected from one of graphene, boron nitride, black phosphorus, GaTe, MXene, and transition metal chalcogenides. Specifically, the transition metal chalcogenides include, but are not limited to, MoS 2 and WSe 2 . It can be understood that the two-dimensional material A and the two-dimensional material B of the present invention can be the same or different.

[0047] The SERS substrates of two-dimensional materials such as molybdenum disulfide (MoS 2 ) and graphene achieve enhanced Raman scattering based on chemical mechanisms such as charge transfer and transition resonance between the molecule to be detected and the two-dimensional material. Since there are no dangling bonds on the surface of the two-dimensional material, the molecules are mainly adsorbed through van der Waals interactions without bonding with the molecule to be detected, thus avoiding the destruction of its structure. Therefore, its measurement spectrum has high time stability and repeatability, and can simplify the analysis process of the detected molecular spectrum.

[0048] In some examples, the two-dimensional material A and the two-dimensional material B are each independently selected from one of monolayer materials, multi-layer homogeneous materials, and multi-layer heterogeneous materials. It can be understood that homogeneous materials include monolayer graphene, bilayer graphene, multi-layer graphene, etc.; multi-layer heterogeneous materials include heterostructures composed of graphene / MoS 2 , etc. It can be understood that "multi-layer" includes 2 layers and above.

[0049] As an example, when both the two-dimensional material A and the two-dimensional material B are monolayer two-dimensional materials, a typical structural schematic diagram is as shown in the appendix Figure 1 . The molecules to be detected are C 6 H 6 , C 3 H 2 N 2 S, C 6 H 7 NO. Among them, Figure 1 in (a) represents a sandwich structure composed of two monolayer MoS 2 sandwiching the molecule to be detected; Figure 1 in (b) represents a sandwich structure composed of two monolayer graphenes sandwiching the molecule to be detected; Figure 1 in (c) represents a sandwich structure composed of MoS 2 and a monolayer of graphene sandwiching the molecule to be detected. In the Figure 1 shown structure, when the incident light irradiates the sandwich structure, since there are two-dimensional materials on both sides of the molecule, both its charge transfer transition and the resonance transition within the two-dimensional material will be enhanced, resulting in a higher enhancement effect of the SERS chemical mechanism.

[0050] As an example, when the two-dimensional material A and the two-dimensional material B are multi-layer homogeneous two-dimensional materials or multi-layer heterostructures, a typical structural schematic diagram is as shown in the appendix Figure 2 The molecule to be detected is C 6 H 6 、C 3 H 2 N 2 S, C 6 H 7 NO, where Figure 2 (a) in represents a sandwich structure composed of 3 layers of MoS 2 and 2 layers of MoS 2 sandwiching the molecule to be detected; Figure 2 The two-dimensional materials in (b) are respectively 2 layers of MoS 2 , and a 2-layer heterostructure composed of MoS 2 and graphene; Figure 2 The two-dimensional materials in (c) are respectively a 2-layer heterostructure composed of MoS 2 and graphene, and a 2-layer heterostructure composed of WSe 2 and graphene.

[0051] In some of these examples, it further includes a first substrate, which is stacked on the first enhanced signal layer in a direction away from the core layer; and / or, the surface-enhanced Raman substrate further includes a second substrate, which is stacked on the second enhanced signal layer in a direction away from the core layer. It can be understood that in the present invention, one side of the first enhanced signal layer or the second enhanced signal layer can be placed on the substrate, or both the first enhanced signal layer and the second enhanced signal layer can be placed on the substrate. The substrate can provide support for the sandwich structure of the first enhanced signal layer, the core layer, and the second enhanced signal layer, facilitating experimental measurement.

[0052] In some of these examples, the first substrate and the second substrate each independently include one or more of a silicon wafer, a quartz wafer, a sapphire, and PDMS.

[0053] As an example, one side of the first enhanced signal layer including the two-dimensional material A or the second enhanced signal layer including the two-dimensional material B is placed on the substrate. A typical structural schematic diagram is as shown in the appendix Figure 3 A sandwich structure composed of two single-layer MoS 2 sandwiching the molecule to be detected is placed on the SiO 2 / Si substrate.

[0054] In some of these examples, a first metal layer is further included, and the first metal layer is stacked on the first enhanced signal layer in a direction close to the core layer; and / or, the surface enhanced Raman substrate further includes a second metal layer, and the second metal layer is stacked on the second enhanced signal layer in a direction close to the core layer.

[0055] In some specific examples, the first metal layer and the second metal layer are each independently selected from one or more of Au, Ag, and Cu. More specifically, the thickness of the first metal layer and the second metal layer is 1 nm to 100 nm.

[0056] In some specific examples, the first metal layer has one or more of a micro-nano structure or a rough surface; and / or, the second metal layer has one or more of a micro-nano structure or a rough surface. More specifically, the micro-nano structure refers to a metal layer capable of generating local surface plasmon resonance, and the roughness of the rough surface is 1 nm to 100 nm.

[0057] As an example, Figure 4 and Figure 5 represent 2 single-layer MoS 2 respectively placed on a SiO 2 / Si substrate coated with a thin layer of gold and a PDMS substrate coated with a thin layer of gold, and the molecule to be detected is located between the 2 single-layer MoS 2 . Among them, Figure 4 the thin layer of gold has a flat surface structure, Figure 5 the thin layer of gold has a rough micro-nano surface.

[0058] Specifically, 2 single-layer MoS 2 are respectively and independently adhered to a SiO 2 / Si substrate coated with a thin layer of gold and a PDMS substrate coated with a thin layer of gold to form a SiO 2 / Si / Au / MoS 2 substrate and a PDMS / Au / MoS 2 substrate. After the SiO 2 / Si / Au / MoS 2 substrate adsorbs the molecule to be detected, then the PDMS / Au / MoS 2 is overlapped on it to form a sandwich structure of two-dimensional materials, which can improve the SERS intensity of the molecule to be detected. In addition, the SiO 2 / Si substrate and the PDMS substrate coated with a thin layer of gold (1 - 100 nm) can tightly adsorb the two-dimensional material MoS 2 , and the binding energy between the two-dimensional material and the substrate is greater than that of the two-dimensional material MoS 2The interlayer interaction, while the thin gold layer can also maintain partial optical transparency. Further, after the above structure is tested, the two-dimensional material can be separated, and after the adsorbed molecules are cleaned, it can be reused.

[0059] In the present invention, by separately placing two-dimensional materials constituting the sandwich on a metal substrate with micro-nano structures or a rough surface, a pair of micro-nano structures separated by a two-dimensional material sandwich is constructed. On the basis of achieving an enhanced effect of the chemical mechanism, the bonding contact between the molecule to be detected and the metal is avoided, and it is also beneficial to place the molecule to be detected in a high electric field region. Further combining the advantages of electromagnetic mechanism enhancement, the excitation electric field intensity and light emission efficiency are increased, and the SERS effect is significantly improved.

[0060] The present invention also provides a method for preparing the above surface-enhanced Raman substrate, including the following steps:

[0061] Take two-dimensional material A and prepare a first enhanced signal layer;

[0062] Place one side of the molecule to be detected on the first enhanced signal layer to prepare a core layer;

[0063] Take two-dimensional material B and prepare a second enhanced signal layer;

[0064] Place the second enhanced signal layer on the core layer.

[0065] The present invention also provides an application of the above surface-enhanced Raman substrate in surface Raman scattering detection.

[0066] The following is further described in conjunction with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples, unless otherwise specified, can all be obtained commercially. The instruments used, unless otherwise specified, can all be obtained commercially. The processes involved, unless otherwise specified, are all conventional selections of those skilled in the art.

[0067] In the following specific examples, for the measurement parameters of the raw material components, unless otherwise specified, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0068] Example 1

[0069] Example 1 prepared WSe 2 / CuPc / WSe 2 / SiO 2 / Si substrate.

[0070] (1) First, prepare a substrate. The substrate is a silicon substrate with 300 nm SiO 2 The silicon wafer is cleaned with acetone and isopropanol and dried with nitrogen;

[0071] (2) By evaporating 40 nm of gold on the WSe 2 crystal, then spin-coating the PVP solution and drying it, and then mechanically exfoliating it with a thermal release tape to obtain monolayer WSe 2 two-dimensional material;

[0072] (3) Attach the thermal release tape together with PVP / Au / WSe 2 to the SiO 2 / Si substrate. After heating to 120 °C, release the PVP / Au / WSe 2 thermally on the SiO 2 / Si substrate;

[0073] (4) Immerse the SiO 2 / Si substrate in deionized water and an I 2 / KI aqueous solution to remove PVP and Au in sequence, and then rinse with deionized water to obtain monolayer WSe 2 on the SiO 2 / Si substrate;

[0074] (5) Immerse the WSe 2 / SiO 2 / Si substrate in a 10 -4 mol / L CuPc solution for 1 hour, then rinse and dry with nitrogen to obtain a WSe 2 / SiO 2 / Si substrate with CuPc adsorbed on its upper surface;

[0075] (6) Evaporate gold on the WSe 2 crystal again to assist mechanical exfoliation, prepare a monolayer WSe 2 thin film, and thermally release it on the PDMS substrate;

[0076] (7) Through a two-dimensional material transfer platform equipped with a microscope, align and attach the WSe 2 on the PDMS to the CuPc / WSe 2 / SiO 2 / Si substrate. After heating to make the PDMS lose its adhesion, release the WSe 2 above, and finally prepare a WSe 2 with CuPc molecules sandwiched between two layers of WSe 2 / CuPc / WSe 2 / SiO 2 / Si substrate.

[0077] Optical microscope images of the WSe 2 / CuPc / WSe 2 / SiO 2 / Si substrate are shown in Figure 6As shown, the result shows WSe 2 / CuPc / WSe 2 / SiO 2 / Si substrate has a WSe 2 interlayer structure.

[0078] The substrate prepared in Example 1 was measured under 633 nm laser excitation, and the Raman scattering spectrum is as Figure 10 shown.

[0079] Example 2

[0080] In Example 2, the Raman scattering enhancement of CuPc by the MoS 2 / CuPc / MoS 2 substrate was theoretically calculated.

[0081] MoS 2 / CuPc / MoS 2 The schematic diagram of the substrate structure and the calculation results are as Figure 7 shown, where Figure 7 (a) is the schematic diagram of the MoS 2 / CuPc / MoS 2 substrate structure. By calculating the Raman scattering tensor of the two-dimensional material interlayer structure sandwiching the CuPc molecular system in Example 2 using the first-principles calculation method, the enhancement factor of the two-dimensional material SERS compared to that without the two-dimensional material can be obtained. The calculation results are as Figure 7 (b) shown. It can be seen that within the laser energy range capable of realizing SERS, the interlayer MoS 2 structure can achieve a stronger chemical enhancement effect than monolayer MoS 2 .

[0082] Example 3

[0083] In Example 3, the Raman scattering enhancement of CuPc by the MoS 2 / CuPc / graphene substrate was theoretically calculated using the first-principles calculation method.

[0084] MoS 2 The schematic diagram of the / CuPc / graphene substrate structure and the calculation results are as Figure 8 shown, where Figure 8 (a) is the schematic diagram of the MoS 2 / CuPc / graphene substrate structure, and the calculated enhancement factor results are as Figure 8 (b). It can be seen that this interlayer structure combines the enhancement characteristics of monolayer MoS 2 and monolayer graphene nanoribbons, thus realizing the SERS enhancement effect of two-dimensional materials within a wider excitation light wavelength range.

[0085] Comparative Example 1

[0086] Comparative Example 1 prepared CuPc / WSe 2 / SiO 2 / Si substrate.

[0087] The preparation steps were the same as steps (1) to (5) of Example 1.

[0088] The optical microscope photograph of the CuPc / WSe 2 / SiO 2 / Si substrate is as shown in Figure 9 which indicates that the CuPc / WSe of Comparative Example 1 2 / SiO 2 / Si substrate has a monolayer structure.

[0089] The substrate of Comparative Example 1 was measured under 633 nm laser excitation, and the Raman scattering spectrum is as shown in Figure 10 which. It can be seen from Figure 10 that for CuPc with the same concentration, the WSe of Example 1 2 interlayer structure compared with the monolayer WSe of Comparative Example 1 2 shows that Example 1 has a higher Raman scattering intensity, indicating that the substrate with the interlayer structure of the present invention has a higher chemical mechanism enhancement effect.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A surface enhanced Raman substrate, characterized in that: It includes a first enhanced signal layer, a core layer and a second enhanced signal layer which are stacked in sequence, wherein the first enhanced signal layer includes a two-dimensional material A, the core layer includes molecules to be detected, and the second enhanced signal layer includes a two-dimensional material B, and the two-dimensional material A and the two-dimensional material B are independent of each other.

2. The surface enhanced Raman substrate according to claim 1, characterized in that: The two-dimensional material A and the two-dimensional material B are each independently selected from one of graphene, boron nitride, black phosphorus, GaTe, MXene and transition metal chalcogenides.

3. The surface enhanced Raman substrate according to claim 1, characterized in that: The two-dimensional material A and the two-dimensional material B are each independently selected from a single-layer material, a multi-layer homogeneous material, and a multi-layer heterogeneous material.

4. The surface enhanced Raman substrate according to any one of claims 1 to 3, characterized in that: It also includes a first substrate, which is stacked on the first enhanced signal layer in a direction away from the core layer; and / or The surface enhanced Raman substrate further comprises a second substrate, and the second substrate is stacked on the second enhanced signal layer in a direction away from the core layer.

5. The surface enhanced Raman substrate according to claim 4, characterized in that: The materials of the first substrate and the second substrate are independently selected from one or more of silicon wafer, quartz wafer, sapphire and PDMS.

6. The surface enhanced Raman substrate according to claim 5, characterized in that: It also includes a first metal layer, which is stacked on the first enhanced signal layer in a direction close to the core layer; and / or The surface enhanced Raman substrate further comprises a second metal layer, and the second metal layer is stacked on the second enhanced signal layer in a direction close to the core layer.

7. The surface enhanced Raman substrate according to claim 6, characterized in that: The first metal layer has one or more of a micro-nano structure or a rough surface; and / or, The second metal layer has one or more of a micro-nano structure and a rough surface.

8. The surface enhanced Raman substrate according to claim 6, characterized in that: The metals in the first metal layer and the second metal layer are each independently selected from one or more of Au, Ag and Cu.

9. The method for preparing a surface enhanced Raman substrate according to any one of claims 1 to 8, characterized in that: The steps include: Take two-dimensional material A to prepare a first enhanced signal layer; Placing the molecule to be detected on the first enhanced signal layer to prepare a core layer; Take two-dimensional material B to prepare a second enhanced signal layer; The second enhanced signal layer is disposed on the core layer.

10. Use of the surface enhanced Raman substrate according to any one of claims 1 to 8 or the surface enhanced Raman substrate prepared by the preparation method according to claim 9 in surface Raman scattering detection.

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