As a new atomically layered, two-dimensional material, tin (IV) diselenide (SnSe₂) has attracted extensive attention due to its compelling application in electronics and optoelectronics. However, the great challenge of impurities and the preparation of high-quality ultrathin SnSe₂ nanoflakes has hindered far-reaching research and SnSe₂ practical applications so far. Therefore, a facile chemical vapor deposition (CVD) method is employed to synthesize large-scale ultrathin SnSe₂ flakes on mica substrates using SnSe and Se powder as precursors. The structural characteristics and crystalline quality of the product were investigated. Moreover, Raman characterizations indicate that the intensity of A_1g peak and E_g peak, and the Raman shift of E_g are associated with the thickness of the SnSe₂ nanoflakes. The ultrathin SnSe₂ nanoflakes show a strong surface-enhanced Raman spectroscopy (SERS) activity for Rhodamine 6G (R6G) molecules. Theoretical explanations for the enhancement principle based on the chemical enhancement mechanism and charge transfer diagram between R6G and SnSe₂ are provided. The results demonstrate that the ultrathin SnSe₂ flakes are high-quality single crystal and can be exploited for microanalysis detection and optoelectronic application.

The capability to support large wave vector bulk plasmon polariton (BPP) waves enables the application of hyperbolic metamaterials (HMMs) in sensing. However, there is a challenge arising from the excitation of BPP, and the highly confined polarization waves are unable to meet the requirements of practical application. In this study, an HMM/bilayer silver nanoparticles (Ag NPs) platform is proposed that allows the excitation and utilization of BPP for use as a surface‐enhanced Raman scattering (SERS) substrate. According to the research results, the bilayer Ag NPs provide stronger plasmonic property and act as a light‐matter coupler, so as to generate a large wave vector of scattered light and excite the BPP within the HMM. Besides, Ag NPs provide the nano antenna structure, and decouple the BPP into localized surface plasmon (LSP) that can be used directly to excite the electric fields. In addition, HMM produces a modulating effect on the plasmon resonance peak, which makes it possible to overlap the spectrum of resonance peak with excitation wavelengths, thus leading to a strong absorption peak at the incident laser wavelength region. Experimentally, the platform was applied to achieve SERS detection for adenosine molecules with a concentration of 10 ⁻⁶ M. It is believed that this plasmonic platform has a potential of application in surface‐enhanced spectroscopy.

Since localized surface plasmon (LSP) is capable of generating strong electromagnetic fields, it has achieved extensive applications in surface-enhanced Raman scattering (SERS). As opposed to this, surface plasmon polariton (SPP) has been rarely employed for its weak electric field enhancement. The present study proposed an Ag nanoparticles (AgNPs) and multilayer Au/Al₂O₃ film (MLF) hybrid system, acting as an efficient SERS substrate by coupling LSPs and SPPs resonances. The dispersion relationship indicates that the light scattered by the AgNPs excites the SPP in the MLF, while the electric field is bound to the Au/Al₂O₃ interface and is significantly enhanced. As revealed from the simulated results, SPPs were generated in the MLF and then coupled with each other to generate a bulk plasmon polariton (BPP). As impacted by BPP, the electric fields stimulated by LSP displayed a dramatic increase. Besides, the electric field exhibited increased intensity with the layer of film. As rhodamine 6G (R6G) and malachite green (MG) were employed as the probe molecules, the AgNPs/MLF hybrid structure demonstrated highly sensitive SERS performance, complying with the theoretical simulations. Specific to the mentioned SERS substrate, R6G and MG had the limit of detection of 1.2 × 10⁻¹⁰M and 7.9 × 10⁻⁹M, respectively, demonstrating the prominent prospects of the NPs/MLF hybrid structure in SERS.

The field of semiconductor surface‐enhanced Raman scattering (SERS) substrates has experienced significant advancements, leading to a wide range of applications in several fields. However, the quest for new ultra‐sensitive semiconductor SERS materials is still of utmost importance. In this regard, an efficient and novel substrate, F ₄ TCNQ/MoS ₂ heterostructure is introduced, assisted by V‐shaped aluminum anodic oxide (AAO) nanocavities with different depths. Utilizing the efficient charge transfer of organic/inorganic semiconducting heterostructure and the photoconfinement capability of the nanocavity structure of the AAO nanotemplate, excellent stability, fast sensing, enhanced Raman, and photodegradation activities are achieved. Due to its unique 3D structure, the optimized F ₄ TCNQ/MoS ₂ /AAO with 1500 nm depth achieves ultra‐high sensitivity detection of 9.0×10 ⁻¹⁶ M for conventional probe molecules. Furthermore, precise detection of water contaminants is observed for the first time with a V‐shaped heterostructure due to combined organic/inorganic features that differ significantly from conventional MoS ₂ structures or other metal/inorganic or inorganic/inorganic semiconductors. This research presents a novel and versatile strategy for SERS and demonstrates its diverse potential performance in practical applications.