Study of Optical Properties of Ag/ZnO Core/Shell Nanoparticles

Himanshu Rajbongshi, Suparna Bhattacharjee, Pranayee Datta
Journal of Basic and Applied Engineering Research   unpublished
In this research work, we report the synthesis of Ag/ZnO core/shell nanoparticles via a simple two step wet chemical method using zinc nitrate hexahydrate [Zn(NO 3) 2 .6H 2 O], Potassium hydroxide (KOH) and silver nitrate (AgNO 3) as precursors, Polyvinylpyrollidone (PVP) as capping agent and tri-sodium citrate (Na 3 C 6 H 5 O 7) as reducing agent. The structural and optical properties of Ag/ZnO core/shell structure are characterized by scanning electron microscopy (SEM), high-resolution
more » ... h-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence (PL) spectroscopy. SEM images reveal that all the Ag nanoparticles and Ag/ZnO core/shell nanoparticles are nearly spherical in shape and uniformly distributed. From HRTEM image, core diameter and shell thickness are found to be 15 nm and 3 nm respectively. XRD pattern of Ag/ZnO core/shell indicates formation of face centred cubic(fcc) structure of Ag NPs and hexagonal wurtzite structure of ZnO. The ZnO shell coating over Ag core results in red shifting of surface Plasmon resonance (SPR) peak of Ag core due to increased refractive index of the surrounding medium. The PL spectroscopy of Ag/ZnO core/shell nanoparticles shows quenching of near band edge emission of ZnO. This is due to the transfer of photogenerated electrons from ZnO shell to the Ag core