Preparation and characterization of ZnO/SiO2/Ag nanoparticles as highly sensitive substrates for surface-enhanced Raman scattering

Metal/semiconductor nanostructure materials have been used as surface-enhanced Raman scattering (SERS) active substrates and have drawn much attention due to their widespread applications in both optical and electronics fields. Here, we report a simple approach to prepare a large-scale ZnO/SiO2/Ag nanoparticles (NPs) by the reduction of [Ag(NH3)(2)](+) with the reducing agent SnCl2 center dot H2O in aqueous solution on the surface of activated ZnO/SiO2 microspheres. The thin SiO2 layer inserted between the ZnO and Ag has been demonstrated to be able to passivate the surface states of ZnO and improve the dispersion of Ag on the surface of NPs, thus enhanced the scattering intensity. The fabricated hybrids are found to be effective SERS substrates because of their homogeneous morphology and the ability to create a strong polarization induced local electromagnetic field by the metal-semiconductor heterojunction. (C) 2015 Elsevier B.V. All rights reserved.