Silica Nanolayer on Functional Particles: Structural Variation for the Functional Design

Core-shell particles constitute an important class of hybrid materials, rationally designed through the integration of distinct core and shell components into a well-defined nanostructure and have found broad applications in catalysis, energy conversion, biomedicine, and advanced coatings. Silica has been commonly used as a shell material on functional particles to prepare functional core-shell particles for photocatalysis, dielectric or electric properties, energy storage, and other applications. In this article, we present examples of the preparation of TiO₂/SiO₂ and ZnO/SiO₂ core-shell particles (mainly by the deposition of SiO₂ on TiO₂ and ZnO from solutions). Due to the versatile application and associated materials' variation of TiO₂ and ZnO, coating with SiO₂ has been done to meet the expected performances in the target applications. The structure types and the detailed structures (thickness of the shell and the nanostructure of the shell) were classified, and the preparation to design them by careful experiments was summarized. The synthetic parameters affecting the structure of the TiO₂/SiO₂ or ZnO/SiO₂ core-shell particles will be considered for the hybridization with other materials, not only TiO₂ and ZnO, to design novel functional hybrid materials.