Fabrication of silica nanocapsules containing Ag/Au alloy nanoparticles by galvanic replacement reaction

A straightforward method has been developed to generate silica nanocapsules containing Ag/Au alloy nanoparticles (Ag/Au@silica) by in-situ galvanic replacement reaction between the silica-coated silver (Ag@silica) nanoparticles with aqueous chloroauric acid (HAuCl4). Ag/Au@silica exhibits an optical absorbance derived from the surface Plasmon resonance of the encapsulated Ag/Au alloy nanoparticle. The behaviour of chemical diffusion across the silica shells of Ag/Au@silica is also investigated. It is worthy to noting that this facile synthetic strategy could be amenable to the other systems that involve the use of different combination of materials for the core (Pd/Ag, Pt/Ag alloy nanoparticles) and for the shell (titania).