Synthesis of Ag@AgAu metal core/alloy shell bimetallic nanoparticles with tunable shell compositions by a galvanic replacement reaction

Abstract

A galvanic replacement reaction process was used to synthesize Ag@AgAu metal core, or alloy shell bimetallic nanoparticles, with tunable shell compositions. The Ag@AgAu bimetallic nanoparticles were produced by the galvanic replacement reaction between Ag nanoparticles and HAuCl4. The conditions were identified that will lead the galvanic reaction to the formation of core, or shell nanopatticles, with an alloy shell. The mechanism of formation was closely monitored, by following the evolution of the product particles with high-resolution transmission electron microscopy (HRTEM) and ultraviolet (UV)/Vis spectroscopy. Energy dispersive X-ray (EDX) and UV/Vis spectroscopic characterizations of the particles indicated that they were core/shell nanoparticles. The difference in composition between the core and shell regions of the particles indicated that they were core/shell structured, without having any hollow characteristics.