Selective Deposition of Au onto 40-nm Ag Nanocubes with Excellent Plasmonic Properties and Chemical Stability

Abstract

Silver nanocrystals have received considerable attention owing to their fascinating optical properties known as localized surface plasmon resonance for applications in surfaceenhanced Raman scattering (SERS), optical sensing, near-field optical probing, and biomedical imaging. However, poor chemical and structural stability of Ag element in an oxidative environment hinders the usefulness of SERS in biological system. In contrast, gold is well known for its oxide-free surfaces with excellent biocompatibility but it is not an optical enhancer as efficient as Ag. In this talk, I will use Ag nanocubes with edge length of 40 nm as an example to demonstrate our success in epitaxial growth of an ultra-thin Au protective layer (~ 0.6 nm in thickness) on the template of nanocubes to improve their stability without any compromise of the unique plasmonic property of Ag for SERS detection.