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

► A Pt metal core 2-3 nm in size is coated with a silica shell. ► The core-shell structure is strongly dependent on the reaction conditions. ► The length of PVP is optimized to avoid poor silica coating with multi Pt cores. ► Water and ammonia concentration influence the growth of silica shell.