Preparation of ZnO@SiO2 composite with controllable sizes and tunable fluorescence via alkali-free strategy

In this paper, we present a simple way to achieve the controllable synthesis of composite ZnO@SiO 2 materials. γ-aminopropyltriethoxysilane (APTES) was chosen as the silicon source, and pre-synthesized zinc bromoacetate (ZnBA) was selected the functional metal precursor. By simply regulating the water–ethanol volume ratio, it was possible to simultaneously regulate the sizes of both the composite material and the metal nanoparticles . With an increase in the hydroalcoholic volume ratio from 1:1–3:1, the sizes of the silica materials were increased from 615 to 3020 nm, while the sizes of the ZnO nanoparticles were increased from 3.75 to 6.25 nm. Three ZnO@SiO 2 materials with blue, green, and yellow fluorescence were obtained. More importantly, the hydroalcoholic volume ratio and the particle size of the material showed a good linear relationship. In addition, a “rapid nucleation–aggregation growth” mechanism was proposed, and the controlled growth of metal oxide nanoparticles was explored.