MoS2 nanoplatelets material on hybrid core shell(HyCoS) AuPd NPs for hybrid SERS platform device for detection of R6G and fabrication method of the same

Abstract

A method for manufacturing a SERS platform device for R6G detection is, a) a step of depositing Pd on a substrate and forming a Pd NP template by a first solid-state dewetting (first SSD) process; b) a step of depositing Au on the above Pd NP template and forming a hybrid core-shell (HyCoS) AuPd NP substrate by a second solid-state dewetting (second SSD) process; and c) a step of forming a hybrid SERS platform device by depositing MoS2 nanoplatelets on the HyCoS AuPd NP substrate by a drop casting method; characterized by including the above step.

Description

Technology Field

[0001] The present invention relates to a hybrid SERS platform device integrating hybrid core-shell (HyCoS) AuPd nanoparticles and MoS2 nanoplatelets for R6G detection, and a method for manufacturing the same. Background Technology

[0002] Surface-enhanced Raman spectroscopy (hereinafter referred to as 'SERS') is a powerful optoelectronic analysis approach for the ultra-sensitive detection of chemical and biomedical molecular species at extremely low concentrations (see Non-patent Literatures 1–3). SERS offers attractive opportunities in a wide range of applications such as optoelectronics, photocatalysis, gas sensors, and energy harvesting (see Non-patent Literatures 4–6). In relation to the SERS enhancement mechanism, the electromagnetic mechanism (hereinafter referred to as 'EM') has also been widely adopted. As the dominant mechanism for various configurations of metal micro- and nanostructures (see Non-patent Literatures 5–8), EM is induced by photon-driven excitation of localized surface plasmon resonance (hereinafter referred to as 'LSPR'), enabling a massive enhancement of the localized electromagnetic field that is much stronger than that of the incident photon (see Non-patent Literatures 9–12). Plasmon nanostructures have demonstrated multiple orders of SERS amplification and high resonance intensity due to substrate nanostructures, and effective interaction with target molecules is a desirable characteristic (see Non-Patent Literature 6, 9, 11). Ag and Au are widely applied plasmonic materials with excellent LSPR resonance intensity, stability, and a broad wavelength range where most Raman emission occurs (see Non-Patent Literature 9, 11, 13). Various Ag and Au-based plasmonic platforms for SERS enhancement, such as Ag nanorods, porous AgAu nanoparticles, Ag / GQD, and Au NP / MXene, have been widely studied (see Non-Patent Literature 8, 14–20). Bimetallic hybrid NP configurations can provide extended options for LSPR depending on size and shape (see Non-Patent Literature 8, 19, 20). At the same time, metallic Pd NPs exhibit excellent near-infrared (NIR)Due to their annihilation and chemical stability, they can serve as promising plasmon-enhanced sensing platforms (see Non-patent Literature 8, 21). However, Pd NPs (nanoparticles) have rarely been applied as SERS substrates. Therefore, the development of bimetallic AuPd NPs via droplet epitaxy can serve as a new pathway for SERS applications. Meanwhile, chemical mechanism (hereinafter referred to as 'CM') enhancement has been widely applied as a SERS mechanism for various configurations of semiconductor micro and nanostructures (see Non-patent Literature 22–26). CM involves charge transfer from semiconductor micro and nanostructure substrates to probe molecules. To date, various semiconductor materials such as TiO2, CdS, GQD, MoS2, and ZnO have been proven to be promising SERS substrates through CM enhancement (see Non-patent Literature 23–26). Among them, MoS2, a transition metal dichalcogenide (TMD) semiconductor with excellent chemical stability and activity, is receiving extensive research interest in the fields of chemical catalysis, energy conversion, biochemical sensing, and SERS. MoS2 nanostructures can provide excellent molecular interactions due to covalent Mo and S bonds with numerous absorption edges, and thus can contribute to high charge transfer for robust SERS enhancement (see Non-Patent Literature 27, 29).

[0003] For example, Quan et al. demonstrated ultra-sensitive SERS detection of bilirubin using a MoS2-ZnO-Ag template, where SERS enhancement due to charge transfer between MoS2 and bilirubin could be effectively achieved by CM enhancement (see Non-Patent Literature 30).

[0004] A hybrid platform device capable of improving SERS performance by integrating the performance of such MoS2 nanostructures is required. Prior art literature

[0005] Korean Patent Publication No. 10-2023-0094000 (Substrate for a UV photodetector comprising flamonic hybrid nanoparticles, ZNO quantum dots, and transition metal dichalcogenides, and a UV photodetector using the same)

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[30] Y. Quan, J. Li, M. Hu, M. Wei, J. Yang, M. Gao, Y. Liu, Interface synthesis of MoS2@ZnO@Ag SERS substrate for the ultrasensitive determination of bilirubin, Appl. Surf. Sci. 598 (2022) 153750. https: / / doi.org / https: / / doi.org / 10.1016 / j.apsusc.2022.153750. The problem to be solved

[0007] The object of the present invention is to provide a hybrid SERS platform device incorporating hybrid core-shell AuPd nanoparticles and MoS2 nanoplatelets with enhanced R6G detection, and a method for manufacturing the same.

[0008] The present invention is not limited to the purposes mentioned above, and other unmentioned purposes will be clearly understood from the description below. means of solving the problem

[0009] According to one aspect of the present invention, a method for manufacturing a SERS platform device for R6G detection comprises: a) a step of depositing Pd on a substrate and forming a Pd NP template by a first solid-state dewetting (first SSD) process; b) a step of depositing Au on the Pd NP template and forming a hybrid core-shell (HyCoS) AuPd NP substrate by a second solid-state dewetting (second SSD) process; and c) a step of forming a hybrid SERS platform device by depositing MoS2 nanoplatelets material on the HyCoS AuPd NP substrate by a drop casting method.

[0010] In addition, in step a) above, the deposition of the Pd is characterized by including the deposition of 10 nm of Pd on the substrate by a sputtering process.

[0011] In addition, the first solid-state dewetting (first SSD) process is characterized by being performed in a PLD chamber at 800°C for 450 seconds.

[0012] In addition, in step (a) above, the dome-shaped Pd nanoparticles with gaps are formed on the substrate with an average height and diameter of 35 nm and 135 nm.

[0013] In addition, the substrate is characterized as being a sapphire substrate.

[0014] In addition, in step b) above, the deposition of Au is characterized by including the deposition of 3 nm of Au on the Pd NP template by a sputtering process.

[0015] In addition, the second solid-state dewetting (second SSD) process of step b) above is characterized by being performed at 400℃.

[0016] In addition, in step b), the surface of the Pd core formed with the dome-shaped Pd nanoparticles is formed into a core-shell structure coated with Au nanoparticles, and dome-shaped Au nanoparticles smaller in size than the Pd cores are formed in the gaps between the Pd cores.

[0017] In addition, the MoS2 nanoplatelets material of step c) above is characterized as being a mixture of MoS2 and R6G.

[0018] In addition, the mixture of MoS2 and R6G is characterized by mixing MoS2 and R6G in a volume ratio of 2:1.

[0019] In addition, the mixture of MoS2 and R6G described above is prepared by dissolving molybdenum disulfide (MoS2) nanoplatelets powder in ethanol to obtain 0.25 mg ml -1 10 of the substance produced and Rhodamine 6G (R6G) dissolved in ethanol -6 It is characterized by mixing the substances of the M solution in a 2:1 volume ratio. Effects of the invention

[0020] In a hybrid SERS platform based on MoS2 nanoplates and HyCoS2 AuPd NPs according to one embodiment of the present invention, strong Raman signal enhancement based on charge transport by MoS2 nanoplates and LSPR by HyCoS2 AuPd NPs can be achieved through chemical mechanism (CM) and electromagnetic mechanism (EM) enhancement.

[0021] The enhancement factor (EF) for R6G of the hybrid platform manufactured according to a preferred embodiment of the present invention is ~10 10 It can reach, and the R6G signal can be improved by nearly 10 times. Brief explanation of the drawing

[0023] FIG. 1 illustrates an example of a flowchart for a method of manufacturing a hybrid SERS platform device incorporating hybrid core-shell AuPd NPs and MoS2 nanoplatelets for R6G detection according to one embodiment of the present invention. Figure 2 illustrates an example of manufacturing a hybrid core-shell AuPd NP according to the manufacturing method of Figure 1. FIG. 3 briefly illustrates the detection structure of a hybrid SERS platform device integrating hybrid core-shell AuPd NPs and MoS2 nanoplatelets for R6G detection according to one embodiment of the present invention. FIG. 4 illustrates a schematic diagram of the electromagnetic mechanism (EM) by local surface plasmon resonance (LSPR) of a hybrid SERS platform device manufactured according to one embodiment of the present invention. FIG. 5 illustrates a charge transfer system of a hybrid SERS platform device manufactured according to one embodiment of the present invention. Figure 6 illustrates the SERS characteristics of R6G of a hybrid SERS platform device manufactured according to one embodiment of the present invention. Figure 7 shows the characteristics of HyCoS AuPd NPs fabricated at various temperatures in the second SSD process for a 3 nm AU deposition layer in the method for manufacturing a hybrid SERS platform device of the present invention. Figure 8 illustrates the optical properties of AuPd HyCoS NPs manufactured using 3 nm Au deposition according to one embodiment of the present invention. Figure 9 illustrates the FDTD characteristics of AuPd HyCoS NPs manufactured using 3 nm Au deposition according to one embodiment of the present invention. FIG. 10 shows a comparison of Raman and SERS spectral characteristics between a hybrid core-shell (HyCoS) AuPd NP device manufactured according to one embodiment of the present invention on a sapphire substrate and various substrate devices. FIG. 11 shows 10 in the state of various SERS sensing substrate devices (a 2:1 mixture of MoS2, AuPd HyCoS NP, and AuPd HyCoS NP). -6 This is a graph comparing the total SERS intensity of M R6G. FIG. 11 shows 10 in the state of various SERS sensing substrate devices (a 2:1 mixture of MoS2, AuPd HyCoS NP, and AuPd HyCoS NP). -6 This is a graph comparing the total SERS intensity of M R6G. FIG. 12 illustrates a schematic diagram of an FDTD simulation of a hybrid SERS platform manufactured according to one embodiment of the present invention and its characteristics. FIG. 13 illustrates a schematic diagram of an R6G Raman signal detection mechanism by a hybrid SERS platform manufactured according to one embodiment of the present invention. FIG. 14 shows a 2:1 mixture of MoS2 and 10 AuPd HyCoS NPs prepared according to a preferred embodiment of the present invention. -6 This illustrates the LOD characteristics of a SERS platform device with M R6G applied. Specific details for implementing the invention

[0024] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0025] In this application, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0026] Additionally, terms such as “…part,” “…unit,” “module,” and “device” described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0027] In addition, terms such as "first," "second," etc., may be used when describing the components of the embodiments of the present invention. These terms are intended merely to distinguish the component from other components, and the essence, order, or sequence of the component is not limited by such terms. Where it is stated that a component is "connected," "combined," or "connected" to another component, it should be understood that while the component may be directly connected, combined, or connected to the other component, another component may also be "connected," "combined," or "connected" between the component and the other component.

[0028] Hereinafter, a hybrid SERS platform device integrating hybrid core-shell (HyCoS) AuPd NPs (nanoparticles, hereinafter referred to as 'NPs') and MoS2 nanoplatelets for R6G detection according to an embodiment of the present invention and a method for manufacturing the same will be described in detail.

[0029] According to one embodiment of the present invention, the development of bimetallic AuPd NPs can be a viable approach to induce strong EM-based SERS enhancement, and strong CM enhancement can be utilized by MoS2 nanostructures to increase the originally weak Raman signal.

[0030] To this end, a SERS platform device comprising HyCoS AuPd NPs and MoS2 nanoplatelets in a single SERS substate according to one embodiment of the present invention was developed based on the idea that it can serve as an effective platform capable of simultaneously applying CM and EM.

[0031] FIG. 1 illustrates an example of a flowchart for a method of manufacturing a hybrid SERS platform device incorporating hybrid core-shell AuPd NPs and MoS2 nanoplatelets for R6G detection according to one embodiment of the present invention.

[0032] Figure 2 illustrates an example of manufacturing a hybrid core-shell AuPd NP according to the manufacturing method of Figure 1.

[0033] Referring to FIG. 1 and 2, a method for manufacturing a hybrid SERS platform device integrating a hybrid core-shell AuPd NP and MoS2 nanoplatelets for R6G detection according to one embodiment of the present invention first performs the step (step 110) of depositing Pd on a substrate and then forming a Pd NP template by a first SSD process.

[0034] According to one embodiment of the present invention, at step 110, 6 × 6 mm 2 A 430 μm thick c-plane sapphire (Al2O3) (0001) wafer (iNexus Inc) with ± 0.1 off-axis of size is used as a substrate (10). In one embodiment of the present invention, first, prior to step 110, the Al2O3 substrate is placed in a pulsed laser deposition (PLD) chamber at a thickness of 1.0 x 10 -4A process is performed to remove trapped oxides, fine particles, and water vapor by degassing at 600°C for 30 minutes at torr. The shape of the degassed sapphire substrate (10) has a smooth surface in the UV-VIS-NIR region and flat optical transmittance and reflectance characteristics. According to one embodiment of the present invention, the surface roughness of the degassed sapphire substrate is less than 1 nm, and the average transmittance and reflectance are ~15% and 84%, respectively. In step 110, a 10 nm Pd deposition layer (11) is deposited on the substrate (10) through a sputtering process. In a preferred embodiment of the present invention, the base pressure inside the sputtering chamber is 1 x 10 -1 The deposition rate is set to less than torr and is performed at approximately 0.05 nm / s using an ionization current of 3 mA. Then, a first solid-state dewetting (SSD) process is performed in a PLD chamber at 800°C for 450 seconds to form gap-shaped dome-shaped Pd nanoparticles (12) on the substrate (10). According to a preferred embodiment of the present invention, the average height and diameter of the Pd NP (12) are formed to be ~35 nm and 135 nm.

[0035] In step 110, a Pd NP template (15) is formed by deformed droplet epitaxy (hereinafter referred to as 'DE') by annealing a 10 nm Pd film through a first Solid-State Dewetting (SSD) process at 800°C for 450 seconds according to a preferred embodiment. In one embodiment of the present invention, to obtain well-separated metal NPs, the Tamman temperature (T Tammam ) is selected, and at this temperature, atoms can be activated for surface diffusion to find a crystal lattice under appropriate annealing conditions (see Non-Patent Literature 12). T TammamIt is about half the absolute metal melting point. Since the melting temperature of Pd is 1555°C, the preferred optimal droplet epitaxy temperature of the present invention is set to ~800°C, taking into account the heat loss of the vacuum system. After annealing, Pd atoms can diffuse and the separated Pd NP template (15) can successfully proceed through the formation of metal droplets by DE, which is induced by atomic diffusion by minimizing surface energy.

[0036] Next, a step (120) is performed in which Au is deposited on a Pd NP template (15) and a hybrid core-shell (HyCoS) AuPd NP (25) substrate is formed by a second SSD process.

[0037] In step 120, in a preferred embodiment of the present invention, a 3 nm Au film is deposited on a Pd NP template through a sputtering process to form an Au deposition layer (20), and then a hybrid core-shell (hereinafter referred to as 'HyCoS') AuPd NP (25) substrate including an Au nanoplate (22) is formed through a second SSD process at 400°C. In a preferred embodiment of the present invention, the second SSD process is performed for 120 seconds.

[0038] And after step 120, a step (step 130) is performed to form a hybrid SERS platform device by depositing MoS2 nanoplatelets on a HyCoS AuPd NP substrate using a drop casting method.

[0039] In step 130 above, the MoS2 nanoplatelets material according to a preferred embodiment of the present invention may be applied as a MoS2 nanoplatelets mixture material in which MoS2 and R6G materials are mixed in a 2:1 volume ratio.

[0040] In step 130, Rhodamine 6G (R6G) is dissolved in ethanol (Sigma Aldrich) and 10 -3 After preparing the M stock solution, further dilute the prepared solution to 10 -4 from 10 -8 R6G at various molar concentrations up to M concentration was prepared, and molybdenum disulfide (MoS2) nanoplatelet powder was dissolved in ethanol to produce 0.25 mg ml -1 A hybrid SERS platform device is created by applying a mixture of MoS2 nanoplatelets in which MoS2 and R6G materials are mixed in a 2:1 volume ratio, and depositing the mixture of MoS2 and R6G materials onto a HyCoS AuPd NP substrate using a drop casting method.

[0041] FIG. 3 briefly illustrates the detection structure of a hybrid SERS platform device integrating hybrid core-shell AuPd NPs and MoS2 nanoplatelets for R6G detection according to one embodiment of the present invention.

[0042] Referring to FIG. 3, a hybrid surface-enhanced Raman spectrometer (SERS) platform according to one embodiment of the present invention can effectively detect SERS signals on a CCD by simultaneously applying electromagnetic mechanisms (EM) and chemical mechanisms (CM) through a combination of hybrid core-shell (HyCoS) AuPd nanoparticles (25) and MoS2 nanoplatelets.

[0043] FIG. 4 illustrates a schematic diagram of the electromagnetic mechanism (EM) by local surface plasmon resonance (LSPR) of a hybrid SERS platform device manufactured according to one embodiment of the present invention.

[0044] Referring to Figure 4, the electromagnetic mechanism (EM) enhancement is indicated by the intense excitation of the LSPR to the plasmonic HyCoS AuPd NP.

[0045] FIG. 5 illustrates a charge transfer system of a hybrid SERS platform device manufactured according to one embodiment of the present invention.

[0046] Figure 5 indicates that CM enhancement is achieved through charge transfer to the HOMO and LUMO levels of R6G in MoS2 nanoplatelets.

[0047] Figure 6 illustrates the SERS characteristics of R6G of a hybrid SERS platform device manufactured according to one embodiment of the present invention.

[0048] Referring to Figure 6, the significant SERS enhancement of R6G is ~10 compared to the basic HyCoS AuPd NP. 10 It can be seen that this is achieved by applying both CM and EM through a mixed approach that reaches the enhancement factor of .

[0049] Figure 7 shows the characteristics of HyCoS AuPd NPs fabricated at various temperatures in the second SSD process for a 3 nm AU deposition layer in the method for manufacturing a hybrid SERS platform device of the present invention.

[0050] Figure 7 shows the characteristics for various temperatures to adopt the optimal annealing temperature in the second SSD process for a 3nm AU deposition layer.

[0051] Figures 7 (a) to (c) show AFM planar views of AuPd NPs subjected to the second SSD process at annealing temperatures of 400, 600, and 800°C. Figures 7 (a-1) to (c-1) show enlarged AFM planar views. Figures 7 (a-2) to (c-2) show the line profiles (blue arrows) of the AuPd NPs (a-1) to (c-1). Figures 7 (a-3) to (c-3) show the line profiles of the background (BG) Au NPs. Figures 7 (d) to (f) show the Rq, SAR, and atomic percentage plots of AuPd HyCoS NPs for the corresponding temperatures. Figures 7 (g) to (g-1) show the EDS phase maps of Pd and Au at an annealing temperature of 400°C. Figure 7 (g-3) shows the corresponding line profile shown in (g).

[0052] Figure 7 shows the surface morphology evolution of hybrid core-shell (HyCoS) AuPd nanoparticles (NP) with a 3 nm Au coating applied to a Pd NP template at various annealing temperatures.

[0053] During the second SSD process according to one embodiment of the present invention, Au atoms coated on Pd NPs can undergo a diffusion process toward a high chemical potential position of the Pd NPs activated by thermal energy, which indicates the formation of a core-shell structure in which the surface of the Pd core, which is a dome-shaped Pd nanoparticle, is coated with Au Np as shown in FIG. 3. At the same time, a thin Au film having the nanometer variation in the gap between the Pd cores, which are the dome-shaped Pd nanoparticles, can easily form stable dome-shaped Au NPs themselves with a size smaller than the Pd cores in the background through internal diffusion and surface energy minimization, thereby increasing the density of background (BG) Au NPs. In one embodiment of the present invention, the high-density BG NPs together with the core-shell AuPd NPs at the basic Pd NP sites are represented as hybrid core-shell (HyCoS) AuPd NPs.

[0054] The surface morphology evolution of HyCoS AuPd NPs at various annealing temperatures is illustrated in Figs. 3 and 7. Referring to Figs. 7(a)–(c), the Pd NPs remained stable regardless of the DE temperature. The gradual decrease in the height of the core-shell NPs may be due to the enhanced diffusion of Au atoms, which is a characteristic of thin film dewetting by DE. Nevertheless, as can be seen in Figs. 7(a-3)–(c-3), the size of the secondary BG Au NPs increased at higher annealing temperatures because the formed Au NPs tend to absorb adjacent atoms and can grow further. It is observed that the average height and diameter of the core-shell AuPd NPs gradually decrease as the annealing temperature increases. The overall transition of the NP morphology can be evaluated by the RMS surface roughness (Rq) and surface area ratio (SAR), as can be seen in Figs. 7(d)–(e).

[0056] Rq represents the root mean square of the height and can be calculated using the following mathematical formula 1.

[0057] [Mathematical Formula 1]

[0058]

[0059] Here, H n is the height profile of each pixel.

[0060] In addition, SAR represents the ratio of the 3D surface area (As) to the geometric area (Ag) using the following mathematical equation 2 relationship.

[0061] [Mathematical Formula 2]

[0062]

[0064] The dominant effect here may be related to the change in core-shell NP size, as this is more significant compared to BG Au NPs. Therefore, both Rq and SAR show a decreasing trend with increasing annealing temperature. It was found that the core-shell NP size decreases as the BG NPs grow. The atomic percentages of this set are summarized in Fig. 7(f). The increased Pd% can be explained by the decrease in Au% due to sublimation at high annealing temperatures and vapor pressures.

[0065] Figure 7(g) shows an SEM image of HyCoS AuPd NPs at 400°C, revealing a basic core-shell AuPd NP surrounded by a high-density background Au NP. Figures 7(g-1) and (g-2) show the EDS elemental phase maps of Pd Lα1 and Au Mα1, which show good agreement with the corresponding SEM images.

[0066] It appears that Pd atoms are well retained at the primary NP sites, whereas Au atoms are present at both primary and background NP sites. The EDS elemental line profile is shown in Fig. 7(g-3), where the intensity of Au is found everywhere with higher numbers at the primary NP sites, whereas the number of Pd atoms is found only at the primary NP sites. This indicates the preferential diffusion of Au atoms toward Pd NPs with low surface energy or high chemical potential, and the formation of secondary background Au NPs. The average diameter of the background Au NPs is measured to be ~22 nm.

[0067] The diverse diffusion behaviors of the evolutionary trend in the second SSD process can be explained by the mixing process promoted at the Pd / Au interface due to increased Au atomic weight and miscibility between Au and Pd atoms.

[0068] Figure 8 illustrates the optical properties of AuPd HyCoS NPs manufactured using 3 nm Au deposition according to one embodiment of the present invention.

[0069] FIGS. 8(a) to (c) show plots of extinction (E), reflectance (R), and transmittance (T) in the 300-1100 nm wavelength range of AuPd HyCoS NPs prepared using 3 nm Au deposition according to an embodiment of the present invention. FIGS. 8(a-1) to (c-1) show normalized E, R, and T plots. FIGS. 8(a-2) to (c-2) show the corresponding contour plots.

[0070] Figure 8 shows the optical properties of HyCoS AuPd NPs using a 3 nm Au coating. Here, the reflectance (R) and transmittance (T) spectra were measured within the UV-VIS-NIR range (300–1100 nm), and the extinction spectra were extracted from the following Equation 3.

[0071] [Mathematical Formula 3]

[0072]

[0074] As can be seen in Fig. 8(a), the 3 nm Au film on sapphire exhibits an extinction peak at ~450 nm due to local surface plasmon resonance (LSPR) induced by the nanoscale film. The Pd NPs exhibited a broad visible peak centered at a peak located at up to 490 nm, which is analyzed to be related to dipole resonance (QR) and quadrupole resonance (QR) modes resulting from the excitation of LSPR. The 0°C sample (3 nm Au coating on Pd NPs before annealing) showed a broader resonance peak extending into the visible region, which is analyzed to be likely due to the formation of defects in the Au film caused by the Au nanoparticles and deposition. With increasing annealing temperatures from ambient temperature, the extinction spectrum exhibits a blue shift from 400°C to 800°C, as can be clearly seen in the normalized extinction plot and contour plot of Figs. 8(a-1) and (a-2).

[0075] The LSPR peak intensity decreased slightly at high dewetting temperatures. The corresponding reflectance and transmittance spectra are shown in Figs. 8(b)–(c) and generally agree well with the extinction plot. The dip in the RT plot corresponds to the peak in the E plot. A decrease in reflectance at lower wavelengths is observed due to backscattering of the HyCoS NP according to one embodiment of the present invention. Both the R and T spectra appear to follow a blueshift trend, as can be clearly seen in Figs. 7(b-2), (c-2) and Figs. 8(c-1)–(c-2). The normalized ERT plot clearly shows the consistent evolutionary trends of the dip, peak, and bandwidth.

[0076] Synthesizing these characteristics, HyCoS AuPd NPs formed at 400℃ exhibited the strongest extinction characteristics, and it is analyzed that this can exhibit the strongest LSPR characteristics.

[0077] Figure 9 illustrates the FDTD characteristics of AuPd HyCoS NPs manufactured using 3 nm Au deposition according to one embodiment of the present invention.

[0078] Figures 9 (d) to (f) show the FDTD schematic representations for general Pd, background (BG) Au, and HyCoS AuPd NPs, respectively. Figures 9 (d-1) to (f-1) show the top-view of the electromagnetic field distribution profiles.

[0079] In Fig. 9, the LSPR characteristics of various metal nanostructures were analyzed using Finite Difference Time Domain (FDTD) simulations. Here, the total field scattering source was adopted as a light source, and the incident wave was perpendicular to the metal NPs to generate electromagnetic hotspots. Schematic diagrams of pure Pd, background (BG) Au, and HyCoS AuPd NPs are shown in Figs. 9(d)–(f), and planar diagrams of the corresponding electromagnetic field distributions are shown in Figs. 9(d-1)–(f-1). The maximum electromagnetic field strength from the pure Pd NPs due to the DE in Fig. 9(d) is observed at the boundary of the NPs. The pure Pd NPs showed a maximum local electromagnetic field strength (MLEI / Emax) of 5.03 in Fig. 9(d-1). To investigate the background NP effect, the high density of Au NPs was simulated separately in Fig. 9(e). High-density small Au NPs exhibited an MLEI of 17.01 in Fig. 9(e-1), which was approximately 2.4 times higher than that of pure Au NPs, indicating that small high-density NPs can exhibit significantly higher localized electric field strengths. This is analyzed as a hotspot density that can greatly aid in SERS enhancement. Additionally, HyCoS AuPd NPs showed a significantly increased MLEI value of 22.3 in Fig. 9(f-1), which was 3.7 times higher than that of pure Pd NPs. This large MLEI enhancement may be caused by electric fields strongly localized within the nanogap through EM coupling between BG Au NPs. Furthermore, the increase in LSPR is analyzed as being due to the maximum intensity of the electric field distribution found at the edges of the AuPd core-shell NPs. In addition, the hybrid core-shell (HyCoS) AuPd NP according to one embodiment of the present invention is analyzed to exhibit the highest LSPR excitation due to the unique configuration of core-shell NPs and high-density BG NPs suitable for plasmonic SERS substrates.

[0080] FIG. 10 shows a comparison of Raman and SERS spectral characteristics between a hybrid core-shell (HyCoS) AuPd NP device manufactured according to one embodiment of the present invention on a sapphire substrate and various substrate devices.

[0081] FIG. 10(a) shows the characteristics of Raman and SERS spectrum simulation results of Rhodamine 6G (R6G) following MoS2 and R6G implantation for a hybrid core-shell (HyCoS) AuPd NP device manufactured according to an embodiment of the present invention and various substrate devices. FIG. 10(b) shows the intensity count of the characteristic peak in (a). FIG. 10(c) shows the SERS spectrum characteristics according to the R6G concentration of the AuPd HyCoS NP substrate. FIG. 10(d) shows a comparison of the intensity of the characteristic peak in (c). FIG. 10(e) shows the SERS spectrum characteristics of various mixing ratios of MoS2 nanoplates and R6G. FIG. 10(f) shows a comparison of SERS enhancement in (e).

[0082] Figure 10 shows the Raman and SERS analyses of Rhodamine 6G (R6G) on various substrates. According to the simulation and FDTD results in Figure 10, the HyCoS AuPd NP template with a 3 nm Au coating annealed at 400°C, which is a preferred embodiment of the present invention, was analyzed to exhibit the best LSPR characteristics. Figure 10 (a) shows the SERS signals of R6G on bare sapphire, MoS2 nanoplatelets, and HyCoS AuPd NP substrates, and the SERS enhancement is compared in Figure 10 (b). Specific values ​​for this set are provided in the following Table 1.

[0083] [Table 1]

[0084]

[0085] Table 1 shows 10 on various substrates in relation to Fig. 10 (b).-6 This is a summary table of SERS peak counts for M R6G. In Table 1, the counts are in thousands (i.e., × 10⁻⁶). 3 It represents ).

[0086] Referring to FIG. 10, FIG. 10 (a-1) shows 20 μl of 10 on sapphire -6 This indicates drop casting of the M R6G solution. In Fig. 10 (a-1), it is analyzed that the Raman signal of R6G was not observed because sapphire is not a SERS substrate. 573 and 746 cm⁻¹ -1 The peak located at may be related to the vibrational modes of sapphire.

[0087] Fig. 10 (a-2) shows 20 μl of 10 in MoS2 / sapphire -6 It indicates the application of M R6G. Fig. 10 (a-2) shows MoS2 nanoplatelet powder dissolved in ethanol to a concentration of 0.25 mg / ml. Fig. 10 (a-2) shows 612, 770, 1360, and 1419 cm⁻¹. -1 It can be seen that a series of intense SERS peaks of R6G, such as [shown here], are observed along with additional peaks. It is analyzed that the application of R6G to MoS2 nanoplates induces R6G SERS through the enhancement of the chemical mechanism (CM) via charge transfer. Meanwhile, additional peaks may have been induced due to edge defects of the MoS2 nanoplates.

[0088] [Table 2]

[0089]

[0090] Table 2 shows 10 mixed solutions (MoS2:R6G) of MoS2, HyCoS AuPd, and AuPd HyCoS NPs at various peak positions. -6 This represents the enhancement factor (EF) of M R6G. The SERS enhancement factor of R6G by MoS2 nanoplatelets is ~10 as calculated in Table 2. 8It is represented as follows. Meanwhile, the SERS enhancement factor of R6G for MoS2 nanoplatelets and the mixed solution (MoS2:R6G) is ~10 as calculated in Table 2. 10 It is represented as.

[0091] FIG. 10(a-3) shows 10 Hy-CoS AuPd NPs prepared according to one embodiment of the present invention -6 This indicates the application of M R6G. In Fig. 10(a-3), strong long-range SERS enhancement was observed at several characteristic peaks of R6G. The SERS enhancement factor of R6G by HyCoS AuPd NPs prepared according to one embodiment of the present invention is ~10 as calculated in Table 2. 9 This was analyzed as exhibiting a strong SERS effect by the HyCoS plasmon template through the enhancement of electromagnetic mechanisms (EM) by strong hot spots and electromagnetic fields via LSPR.

[0092] (a-4) of FIG. 10 shows MoS2 and 10 in a HyCoS AuPd NP template according to one embodiment of the present invention -6 This indicates that a total volume of 20 μl of a 2:1 mixed solution of M and R6G was injected via drop casting. Referring to Figure 10 (a-4), it appears that the SERS were significantly enhanced by applying a mixture of MoS2 and R6G to HyCoS NPs. In this case, the SERS enhancement is analyzed to be related to simultaneous enhancement by chemical mechanisms (CM) and electromagnetic mechanisms (EM). The SERS intensity counts of the characteristic peaks are shown in Figure 10 (b), and the mixing method demonstrates a much enhanced SERS response.

[0093] In another simulation of the present invention, to investigate the SERS behavior of a plasmonic HyCoS AuPd NP template as illustrated in FIG. 10(c), 10 -4 10 in M -8The characteristics were analyzed by applying various ranges of R6G molar concentrations. With increasing molar concentration, the SERS peak intensity gradually increased, as well summarized in Figure 10 (d).

[0094] [Table 3]

[0095]

[0096] Table 3 shows a summary of the number of SERS peaks for changes in R6G molar concentration for HyCoS AuPd NPs at various peak positions in relation to Figure 10(d).

[0097] The gradual SERS enhancement may be due to the gradual increase in molecular concentration caused by effective interactions between the target molecule and high-density hotspots induced by the LSPR of HyCoS AuPd NPs. Hot carriers or electrons excited by strong LSPR and numerous hotspots of HyCoS AuPd NPs can effectively enhance carriers in the highest occupied molecular orbital (hereinafter referred to as 'HOMO') of the R6G molecule. Subsequently, it is analyzed that the electronic transition to the lowest unoccupied molecular orbital (hereinafter referred to as 'LUMO') energy level of the R6G molecule is greatly enhanced through numerous hot carrier transitions, resulting in a significant enhancement of the SERS signal. Clearly, the SERS number can increase as the molar concentration of R6G increases, which demonstrates that HyCoS AuPd NPs are effective SERS substates. Furthermore, the plasmonic template according to one embodiment of the present invention [indicates] the R6G molecule 10 -8 It is shown that it can sensitively detect up to M. Generally, SERS enhancement by metal NP substrates is known as electromagnetic mechanism (EM) enhancement (see Non-Patent Literature 7).

[0098] Fig. 10(e) shows 10 in HyCoS AuPd NPs-6 This shows the change in the ratio of MoS2 nanoplatelets using M R6G. In Fig. 10(e), the total measured volume was fixed at 20 μl, and MoS2 nanoplatelets were used at a unit of 0.25 mg / ml. 10 for HyCoS AuPd NP in Fig. 10(e-4) -6 In the SERS signal of M R6G, the SERS signal increased significantly with the mixed application of MoS2 and R6G in Figs. 10(e-1) to (e-3). The SERS enhancement is summarized in Fig. 10(f), and specific values ​​for this set are shown in Table 4.

[0099] [Table 4]

[0100]

[0102] Table 4 shows various mixed solutions (MoS2: 10) of HyCoS AuPd NP substrates at various peak positions in relation to Fig. 10(f). -6 This shows a summary of the SERS peak numbers of M R6G). In Table 4, the samples are MoS2 nanoplatelets with a concentration of 0.25 mg / ml and 10 -6 It represents the volume ratio of a total of 20 μl of M R6G. The number is in thousands, i.e., × 10 3 It is related to Figure 4(f).

[0103] Referring to Fig. 10(f) and Table 4, MoS2 nanoplatelets with a concentration of 0.25 mg / ml and 10 -6The 2:1 volume ratio of M to R6G exhibited the maximum SERS intensity compared to the other two mixing ratios, and the signal was analyzed to be enhanced by nearly 10-fold. Referring to Figure 10(f) and Table 4, it appears that when the amount of MoS2 is lower (10:1), the potential for SERS enhancement is slightly lower due to less charge transfer caused by the smaller amount. Furthermore, as the amount of MoS2 increases (1:1), the denser MoS2 nanoplatelets can absorb SERS from the R6G molecules. With the application of the mixture, the MoS2 nanoplatelet carriers can be delivered to the most occupied molecular orbital (HOMO) of the R6G molecule. It is analyzed that the increased carrier concentration can then increase the transition from HOMO to LUMO, and carrier excitation within R6G can also be efficiently enhanced. This can significantly increase the overall SERS enhancement. This type of SERS enhancement by semiconductor materials is known as chemical mechanism (CM) enhancement (see Non-Patent Literature 8). In the hybrid approach, it is analyzed that both EM and CM can be utilized with a mixture of MoS2 nanoplates and R6G probe molecules on HyCoS AuPd NPs. Meanwhile, as the concentration of R6G decreased, the enhancement decreased, and 10 -8 It is analyzed that CM improvement is no longer effective in M.

[0104] FIG. 11 shows 10 in the state of various SERS sensing substrate devices (a 2:1 mixture of MoS2, AuPd HyCoS NP, and AuPd HyCoS NP). -6 This is a graph comparing the total SERS intensity of M R6G.

[0105] Figure 11 (a-1) shows the intensity count of the characteristic peak for (a).

[0106] Referring to Fig. 11, the SERS enhancement is analyzed to have increased in the order of MoS2 nanoplatelets < HyCoS AuPd NPs < R6G for MoS2 nanoplatelets and HyCoS AuPd NPs with a 2:1 mixture application, as summarized in Fig. 11(a-1).

[0107] FIG. 12 illustrates a schematic diagram of an FDTD simulation of a hybrid SERS platform manufactured according to one embodiment of the present invention and its characteristics.

[0108] Figure 12 shows the top view and side view of the electromagnetic field distribution (b-1) - (b-2).

[0109] MoS2 nanoplates by CM and HyCoS AuPd NPs by EM are 10 -6 The Raman signal of M R6G can be individually enhanced. Based on this, the mixed approach demonstrates that the SERS response is significantly enhanced due to the synergistic effect of electromagnetic (EM) and chemical (CM) mechanisms. The preferred optimal mixing ratio of the present invention is analyzed to be 2:1. It is analyzed that an appropriate amount of MoS2 nanoplatelets can ensure sufficient adsorption sites for charge transfer to maximize the enhancement of the Raman signal, as previously described.

[0110] FIG. 13 illustrates a schematic diagram of an R6G Raman signal detection mechanism by a hybrid SERS platform manufactured according to one embodiment of the present invention.

[0111] Figure 13(c-1) shows a schematic diagram of the enhancement of Raman signal detection by electromagnetic (EM) and chemical (CM) mechanisms. Figure 13(c-2) shows the charge contribution features by MoS2 nanoplates and plasmonic HyCoS AuPd NPs.

[0112] The corresponding bar graph in Fig. 11(a-1) shows an overview of the rapid detection enhancement achieved by applying a mixed approach. Additionally, the SERS enhancement factor (hereinafter referred to as 'EF') of the R6G was calculated using the following Equation 4 for quantitative analysis of various SERS platforms based on the R6G SERS and the general Raman signal of the R6G.

[0113] [Mathematical Formula 4]

[0114]

[0115] Here I SERS Wow I Raman is SERS, and is the Raman intensity of the characteristic peak.

[0116] 612, 1360, 1648 cm -1 The peak is 3.08 x 10⁻⁶ as summarized in Table 2. 8 , 2.32 x 10 8 and 3.12 x 10 8 Represents the corresponding EF. Then, 10 in HyCoS AuPd NPs by EM -6 For M R6G, SERS EF is ~10 9 It was calculated as. Also, 612, 1360, 1648 cm -1 The peak is 31.56 x 10⁻⁶ in Table 2. 9 , 7.79 x 10 9 and 6.43 x 10 9 It indicates the corresponding EF. And the SERS EF is 10 of the 2:1 mixture -6 For M R6G, that is, for the R6G of MoS2 nanoplates and HyCoS AuPd NPs, ~10 10 It was calculated as 1.59 × 10 10 , 7.82 × 10 10 and 7.19 × 10 10 The corresponding EF is 612, 1360, 1648 cm of the characteristics in Table 2 -1It was calculated for the peaks. The mixed approach is analyzed to show a second-order higher EF compared to MoS2 nanoplates and a first-order higher EF compared to HyCoS AuPd NPs by taking both EM and CM at various characteristic peaks of R6G.

[0117] In addition, to investigate the detection capability of the hybrid platform, the limit of detection (hereinafter referred to as 'LOD') was calculated based on the following mathematical formula 5.

[0118] [Mathematical Formula 5]

[0119]

[0120] Here, σ is the residual standard deviation and b is the slope of the regression line.

[0121] FIG. 14 shows a 2:1 mixture of MoS2 and 10 AuPd HyCoS NPs prepared according to a preferred embodiment of the present invention. -6 This illustrates the LOD characteristics of a SERS platform device applying M R6G. In Fig. 14, a 2:1 mixture of AuPd HyCoS NPs, MoS2, and 10 -6 Using M R6G 10 -8 ~ 10 -6 1360 cm at concentrations in the M range -1 It shows the linear trend of the SERS signal. Referring to Fig. 14, the highest intensity is at 1360 cm⁻¹. -1 The peak was used in the LOD calculation.

[0122] σ was obtained based on 10 blank reads, and the LOD is 6.68 x 10 -1 It was calculated as 0 M. The Raman signal enhancement mechanism for a hybrid SERS platform based on MoS2 nanoplatelets and Hy-CoS AuPd NPs can be related to electromagnetic (EM) and chemical (CM) mechanisms as previously described.

[0123] Figure 12 shows the FDTD simulations performed to investigate the electromagnetic field distribution of a hybrid SERS platform, specifically MoS2 nanoplatelets of HyCoS2 AuPd NPs containing core-shell AuPd NPs along with a high-density small background Au NP. The FDTD scheme is shown in Figure 12(b), where the MoS2 nanoplatelets were placed on top of the metallic AuPd HyCoS2 NPs as in the experimental setup. Plane waves were irradiated perpendicularly to the hybrid SERS platform for local excitation of the LSPR, and the corresponding top and side views of the electromagnetic field distribution are shown in Figures 12(b-1) and (b-2). Here, the maximum local electric field strength (MLEI / Emax) of the hybrid SERS platform is shown to be ~28.0. This indicates a significantly enhanced resonant electromagnetic field strength with the integration of the MoS2 nanoplatelets.

[0124] In addition, a schematic diagram of the R6G Raman signal enhancement by the hybrid SERS platform via CM and EM is shown in Fig. 13(c-1), and a schematic diagram of the charge contribution by MoS2 nanoplates and plasmonic HyCoS AuPd NPs is shown in Fig. 13(c-2). As can be seen from the FDTD simulations in Figs. 12 and 13, the hybrid platform exhibits the highest maximum local electromagnetic field intensity due to plasmonic resonance excitation, resulting from the unique AuPd core-shell structure and high-density background Au NP coupling. It is worth noting that high-density background Au NPs can significantly increase the hotspot density and the interaction cross-section with R6G molecules. In this regard, a large number of hotspots and a strong local electromagnetic field can be generated by laser irradiation, which can effectively enhance charge transfer from AuPd HyCoS NPs to R6G molecules and suggests that the SERS response by EM enhancement is significantly amplified. At the same time, it is analyzed that MoS2 nanoplates possess excellent adsorption capabilities and can excite a large number of electrons to the conduction band by laser irradiation. Additionally, due to the presence of polar covalent bonds (Mo-S), MoS2 nanoplates can provide sufficient adsorption edges to probe molecules through dipole-dipole coupling. Charge transfer can be effectively promoted from the conduction band (CB) of MoS2 to the HOMO of R6G. Furthermore, charge transfer via EM and CM can significantly amplify the Raman signal. Consequently, a hybrid platform according to one embodiment of the present invention, which combines HyCoS2 AuPd NPs and MoS2 nanoplates by utilizing both CM and EM under laser excitation, can significantly enhance the originally weak Raman signal of R6G.

[0125] HyCoS AuPd NP configuration according to one embodiment of the present invention, i.e., an AuPd core-shell structure with high-density background Au NPs, can exhibit the highest resonance intensity in optical measurements and FDTD simulations.

[0126] In addition, FDTD simulations were performed to study the LSPR characteristics of a hybrid SERS platform device according to one embodiment of the present invention, and it was found that strong electric fields were generated at the nanogap and edges of metal NPs.

[0127] In addition, MoS2 nanoplates prepared according to one embodiment of the present invention and 10 -6 The mixture of M R6G exhibited higher SERS signal detection compared to MoS2 nanoplate SERS and had higher intensity enhancement compared to HyCoS AuPd NP SERS.

[0128] In addition, various mixing ratios of MoS2 and R6G (10:1, 1:1, 2:1) were evaluated, and 2:1 was found to be the most optimal.

[0129] In a hybrid SERS platform based on MoS2 nanoplates and HyCoS2 AuPd NPs, strong Raman signal enhancement based on charge transport by MoS2 nanoplates and LSPR by HyCoS2 AuPd NPs was achieved through chemical (CM) and electromagnetic (EM) mechanism enhancements.

[0130] The EM enhancement of the hybrid SERS platform fabricated in a preferred embodiment of the present invention can be derived from a unique plasmonic HyCoS AuPd NP template fabricated by specific droplet epitaxy. This exhibits strong plasmonic excitation of hot spots in the nanogap of the metal NPs and the generation of an abundant electric field due to local surface plasmon resonance (LSPR).

[0131] The excellent LSPR of the hybrid SERS platform fabricated in the preferred embodiment of the present invention could be attributed to the combination of unique AuPd core-shell NPs and high-density background Au NPs. Furthermore, CM enhancement is associated with charge transfer from MoS2 nanoplatelets to R6G, and direct contact via a mixed approach with an optimal mixing ratio effectively facilitated charge transfer from R6G to the HOMO and LUMO, leading to a sequence of Raman signal amplification. The enhancement factor (EF) of the hybrid platform fabricated according to the preferred embodiment of the present invention is ~10 for R6G. 10 Can reach. Explanation of the symbols

[0133] 10: Substrate 11: Pd deposition layer 12: Pd nanoparticles 15: Pd Template 20: Au deposition layer 22: Au nanoplate 25: Hybrid Core-Shell AuPd NP

Claims

Claim 1 A method for manufacturing a SERS platform device for R6G detection, wherein the manufacturing method comprises: a) a step of depositing Pd on a substrate and forming a Pd NP template by a first solid-state dewetting (first SSD) process; b) a step of depositing Au on the Pd NP template and forming a hybrid core-shell (HyCoS) AuPd NP substrate by a second solid-state dewetting (second SSD) process; and c) a step of forming a hybrid SERS platform device by depositing MoS2 nanoplatelets material on the HyCoS AuPd NP substrate by a drop casting method; wherein the substrate is a sapphire substrate. Claim 2 A method for manufacturing a SERS platform device for R6G detection according to claim 1, wherein in step a), the deposition of the Pd includes depositing 10 nm of Pd on the substrate by a sputtering process. Claim 3 A method for manufacturing a SERS platform device for R6G detection according to claim 2, characterized in that the first solid-state dewetting (first SSD) process is performed in a PLD chamber at 800°C for 450 seconds. Claim 4 A method for manufacturing a SERS platform device according to claim 1, characterized in that, in step a), gap-shaped dome-shaped Pd nanoparticles are formed on the substrate with an average height and diameter of 35 nm and 135 nm. Claim 5 delete Claim 6 A method for manufacturing a SERS platform device for R6G detection according to claim 1, wherein in step b), the deposition of Au includes depositing 3 nm of Au on the Pd NP template by a sputtering process. Claim 7 A method for manufacturing a SERS platform device for R6G detection, characterized in that, in claim 6, the second solid-state dewetting (second SSD) process of step b) above is performed at 400℃. Claim 8 A method for manufacturing a SERS platform device for R6G detection according to claim 4, wherein in step b), the surface of the Pd core formed by the dome-shaped Pd nanoparticles is formed into a core-shell structure coated with Au nanoparticles, and dome-shaped Au nanoparticles smaller in size than the Pd cores are formed in the gaps between the Pd cores. Claim 9 A method for manufacturing a SERS platform device for R6G detection, characterized in that, in claim 6, the MoS2 nanoplatelets material in step c) is a mixture of MoS2 and R6G. Claim 10 A method for manufacturing a SERS platform device for R6G detection according to claim 9, wherein the mixture of MoS2 and R6G is characterized by mixing MoS2 and R6G in a volume ratio of 2:

1. Claim 11 In claim 9, the mixture of MoS2 and R6G is obtained by dissolving molybdenum disulfide (MoS2) nanoplatelets powder in ethanol to obtain 0.25 mg ml -1 10 of the substance produced and Rhodamine 6G (R6G) dissolved in ethanol -6 A method for manufacturing a SERS platform device for R6G detection, characterized by mixing the substances of the M solution in a 2:1 volume ratio.

Images