The effect of shell thickness on plasmonic behaviors of Ag@MoS2 core-shell nanoparticles

Abstract

Plasmonic core-shell nanoparticles (CSNPs) have been extensively used as SERS active-substrates because their localized surface plasmonic resonance (LSPR) properties and thus the surface enhanced Raman scattering (SERS) activities can be regulated by changing the shell thickness. In this work, we selected Ag@MoS₂ CSNP with 40 nm radius of Ag as core and varied thickness of MoS₂ as shell to investigate the shell-dependent plasmonic behaviors including LSPR and SERS by using finite difference time domain (FDTD) simulations. The LSPR peak of Ag@MoS₂ CSNPs shows a broad red-shifting with an increasing shell thickness from 0 nm to 40 nm, giving rise to that the LSPR peak tunes from visible region (385 nm) to near infrared (NIR) region (1100 nm). The SERS activity of Ag@MoS₂ CSNP, represented by the enhancement of local electrical field (EM), can also be modulated by changing the shell thickness, and the optimal enhancement factor (EF) under 633 nm laser excitation is determined to be 3.54×10⁶ when the shell thickness is 4 nm. The wide-range LSPR tunability of Ag@MoS₂ CSNP provides enormous potential for NIR SERS application and enhanced photocatalytic activity