Induced SERS activity in Ag@SiO2/Ag core-shell nanosphere arrays with tunable interior insulator

Abstract

In this work, we demonstrated a bottom-up growth of Ag@SiO2/Ag core-shell nanosphere arrays with tunable SiO2 interior insulator and the optimized surface-enhanced Raman scattering (SERS) substrate based on a nanostructure performed with both high sensitivity and large-area uniformity. Their morphological, structural, and optical properties were characterized, and the induced SERS activities were investigated theoretically by the FDTD simulation and experimentally using analyte molecules. An ultrathin SiO2 shell with tunable thickness can be synthesized pinhole-free by a chemical vapor deposition, working as an interior insulator between the Ag core and Ag out-layer coating. A detection limit as low as 10−12 M and an enhancement factor up to 3 × 107 were obtained, and the SERS signal was highly reproducible with small standard deviation. The method opened up a way to create a new class of SERS activity sensor with high-density ‘hot spots’, and it may play an important role in device design and the corresponding biological and food safety monitoring applications. Copyright © 2016 John Wiley & Sons, Ltd.