Highly luminescent silica-coated ZnO nanoparticles dispersed in an aqueous medium

► Highly luminescent silica-coated ZnO nanoparticles can be dispersed in an aqueous medium. ► The prepared samples exhibited an emission peak at around 480 nm (blue color). ► The quantum efficiency was 60% at maximum by ultraviolet excitation. ► No degradation of the PL properties was observed for 7 days following the preparation.