Hollow gold nanoparticles coated with ZnS with distance-dependent plasma coupling and surface enhanced Raman spectroscopy for applications

Abstract

Metal@semiconductor core-shell heterostructure with strong exciton-plasmon coupling can integrate multiple functions of each component and exhibit extraordinary benefits in the optical, catalytic, electrical, and magnetic properties due to its excellent synergistic properties at the heterointerfaces. In our work, hollow gold nanoparticles (HGNs)- 4-mercaptobenzoic acid (MBA) @ZnS core-shell heterostructure with the adjustable shell thickness (tshell) of ZnS varied from 1 to 19 nm were successfully prepared for the first time by low temperature and simple two-step method. Here, we report our findings that the surface enhanced Raman scattering (SERS) spectral intensity of HGNs-MBA@ZnS under the 633 nm excitation correlates with the tshell of ZnS, and the experimental results are consistent with theoretical studies. Furthermore, we also investigated the excitation wavelength-dependent SERS enhancement mechanism of HGNs-MBA@ZnS (tshell = 2 nm) and the result showed that the near-field enhancement and plasmon-induced interfacial charge transfer transition (PICTT) synergistically increase the SERS intensity under the excitation line at 633 nm. Our work not only provides guidance for the design and synthesis of other important metal@semiconductor core-shell heterostructure, but presents significant insights into their SERS enhancement mechanism.