Synthesis of core-shell nanoparticles with a Pt nanoparticle core and a silica shell

摘要

A method to prepare a core-shell structure consisting of a Pt metal core coated with a silica shell (Pt(in)SiO _2) is described herein. A silica shell was grown on poly(vinylpyrrolidone) (PVP)-stabilized Pt nanoparticles 2-3 nm in size through hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) in a water/ethanol mixture with ammonia as a catalyst. This process requires precise control of the reaction conditions to avoid the formation of silica particles containing multiple Pt cores and core-free silica. The length of PVP molecules, water content, concentration of ammonia and Pt nanoparticles in solution were found to significantly influence the core-shell structure. By optimizing these parameters, it was possible to prepare core-shell particles each containing a single Pt nanoparticle with a silica layer coating approximately 10 nm thick.