Synthesis and Oxidation of Silver Nano-particles

We demonstrated a fast and easy way to synthesize Ag nanoparticles (NPs) on ZnO nanowires (NWs) and silicon substrates by an electroless (EL) plating approach. ZnO NWs used here were grown via vapor-solid (VS) mechanism at 560 oC for 30 min. The stability to oxidation of these EL-produced homogeneous Ag NPs on ZnO nanowires was investigated by surface enhanced Raman spectroscopy (SERS), showing that the attachment of thiol to the Ag surface can slow down the oxidation process, and the SERS signal remains strong for more than ten days. Furthermore, we examined the surface oxidation kinetics of the Ag NPs as a function of NPs size and size distribution by monitoring the oxygen amount in the composites using energy dispersive x-ray (EDX). Results indicate that the EL plated Ag NPs show faster oxidation rates than those produced by e-beam (EB) evaporation in air. We attribute this to the fact that the EL produced silver particles are very small, in the 20 nm range, and thus have high surface energy, thus enhancing the oxidation. These studies provide extensive information related to the Ag NP oxidation rates, which can help in extending the Ag lifetime for various applications.