Fabrication of SiO2@Ag@SiO2 core–shell microspheres and thermal stability investigation

Uniform, dense, and thickness controllable silver shells coated on mono-dispersed SiO2 microspheres were prepared by one-pot silver mirror reaction on the surface of Sn2+-sensitized colloidal SiO2 spheres. Different thickness of SiO2-encapsulating layer was fabricated by the hydrolysis of tetraethyl orthosilicate (TEOS) in isopropanol solution. The change of the Ag shell with the heating process could be reflected from the UV–vis absorption spectrum. The outer SiO2 layer provided greatly improved thermal stability of the Ag shell (20 nm) up to 300 °C.