LAUSR

In this study, we designed shell-dependent Ag@Cu2O core–shell nanoparticles (NPs) for SERS study. Compared to Cu2O NPs, Ag@Cu2O core–shell NPs exhibited high SERS activity because of the localized surface plasmon resonance (LSPR) from Ag core. For electron–hole pairs in Cu2O, the plasmon-induced resonant energy transfer from silver to Cu2O and the direct electron transfer can be simultaneously observed from the SERS intensity and the red-shift of the extinction spectra. Therefore, charge separation between silver and Cu2O will lead to high SERS activity. Moreover, the SERS activity of the Ag@Cu2O core–shell NPs can be modulated by changing the shell thickness, and it was found that SERS was optimal for the shell thickness of around 31 nm. The proposed enhancement mechanism can be extended to any metal–semiconductor complex system, which is contributed from plasmonic-induced SERS.