Hot Electron-Mediated Ultrasensitive Sensing in Plasmonic Ag/2D-MoS2 Nanostructures

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Abstract
Surface-enhanced Raman scattering (SERS) stands out as a powerful analytical technique, offering exceptional capabilities in molecular detection and characterization distinguished by its extraordinary sensitivity, high selectivity, and versatility. In this study, we present the synthesis of silver nanostructures, primarily triangular silver nanostructure (t-Ag NS) in morphology, which exhibits plasmonic properties. When dispersed on a seamless monolayer of 2D-MoS2 (t-Ag NS/MoS2), these nanostructures facilitate the formation of a Schottky barrier and induce a phase transition in MoS2 from the 2H semiconducting phase to the 1T metallic phase. The Schottky barrier promotes the transfer of plasmonic hot electrons from the metallic Ag nanostructures to the MoS2 layers while preventing recombination through its energy barrier. The transition to the metallic phase, coupled with the dispersion effect, synergistically boosts the overall performance and sensitivity of the sensing device. We further demonstrate the efficacy of t-Ag NS/Ag-MoS2 substrates exhibiting remarkable performance in the detection of dyes such as methylene blue (MB) and brilliant yellow (BY) achieving an impressively high sensitivity at the nanomolar concentration level, reaching as high as 1.1*107 and 8.8*106, respectively., We believe that the newly developed t-Ag NS and their strategic distribution across MoS2 substrates, giving a high enhancement factor (EF) in the nanomolar range, underscore the substrates’ ability to dramatically increase the detection signal, thereby improving the overall sensitivity leading to new possibilities for applications requiring extremely precise and sensitive molecular identification in minute analyte concentration.
Funding Information
  • Anusandhan National Research Foundation (CRG/2022/003204)