Investigation into the molar feeding ratio and temperature dependence on the replacement reaction between platinum ions and silver nanoparticles

Abstract

The deliberate structuring of bimetallic nanoparticles has useful applications in both fuel cell applications and biomedical research. This thesis studies the replacement reaction between platinum ions and silver nanoparticles, with the goal of synthesizing platinum-shelled silver nanoparticles. Specifically, the molar feeding ratio and the temperature dependence on the reaction were investigated. At low levels of supplied platinum, the nanoshells were only partially formed, but at a 1:1 molar ratio, non-uniform thickness nanoshells were formed with large amounts of silver on the surface. The temperature dependence showed increasingly thick shell formation; however, cyclic voltammetry measurements indicated the surface of the nanoparticles contained excessive levels of silver, deeming the particles inadequate for use as fuel cell catalysts. Through high temperature reactions, the surface plasmon resonance excitations peaks of the silver nanoparticles were shifted 100nm higher, pushing the peaks closer to the visible spectrum from the deep ultraviolet region.