Surface-enhanced Raman scattering (SERS) substrates based on chemical mechanism (CM) have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability, uniform molecular adsorption and controllable molecular orientation. However, it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate. Herein, we demonstrate a graphene oxide (GO) energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity. The Fermi level (E_f) of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate. Experimentally, kelvin probe force microscopy (KPFM) is employed to quantitatively analyze the E_f of GO. Theoretically, the density functional theory calculations are also performed to verify the proposed modulation mechanism. Consequently, the SERS response of probe molecules with different band structures (R6G, CV, MB, PNTP) can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate. This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.

Regulation of hot spots exhibits excellent potential in many applications including nanolasers, energy harvesting, sensing, and subwavelength imaging. Here, hat‐shaped hierarchical nanostructures with different space curvatures have been proposed to enhance hot spots for facilitating surface‐enhanced Raman scattering (SERS) and plasmon‐driven catalysis applications. These novel nanostructures comprise two layers of metal nanoparticles separated by hat‐shaped MoS ₂ films. The fabrication of this hybrid structure is based on the thermal annealing and thermal evaporation of self‐assembled polystyrene spheres, which are convenient to control the metal particle size and the curvature of hat‐shaped nanostructures. Based on the narrow gaps produced by the MoS ₂ films and the curvature of space, the constructed platform exhibits superior SERS capability and achieves ultrasensitive detection for toxic molecules. Furthermore, the surface catalytic conversion of p‐nitrothiophenol (PNTP) to p, p′‐dimercaptobenzene (DMAB) was in situ monitored by the SERS substrate. The mechanism governing this regulation of hot spots is also investigated via theoretical simulations.

Highly efficient plasmon‐driven catalysis and excellent surface‐enhanced Raman spectroscopy (SERS) performance are proportional to the square of the local electromagnetic field (hot spot). However, a proven way to realize the enhancement in intensity and density of “hot spot” still needs to be investigated. Here, we report on multilayered Ag nanoparticle (Ag NP)/graphene coupled to an underlying Cu film system (MAgNP‐CuF) which can be used as an effective SERS substrates realizing ultra‐sensitive detection for toxic molecules and in situ monitoring the plasmon‐driven reaction for p‐nitrothiophenol (PNTP) to p,p′‐dimercaptobenzene (DMAB) conversion. The mechanism of ultra‐sensitive SERS response and catalytic reaction is investigated via Ag NP/graphene layer‐dependent experiments combined with theoretical simulations. The research found that the intensity and density of “hot spot” can be effectively manipulated by the number of plasmonic layers, and the bottom Cu film could also reflect the scattered and excitation beam and would further enhance the Raman signals. Moreover, the MAgNP‐CuF exhibits outstanding performance in stability and reproducibility. We believe that this concept of multilayered plasmonic structures would be widely used not only in the field of SERS but also in the wider research in photocatalysis.