Surface charge control of hierarchical ceria/silica hybrid shells for enhanced dispersion stability

Although ceria particles are currently receiving great interest with their unique catalytic and optical properties, the problem of agglomeration is yet to be overcome, which is caused by their high density and surface energy, consequently hampering the practical applications. Herein, a novel method of preparing hierarchical shells of ceria (CeO₂) and silica (SiO₂) on a polystyrene (PS) core is introduced to control the shape and surface charge of the particle, which give rise to different dispersion conditions. The PS/CeO₂/SiO₂ hybrid core–shell microspheres provide a wide spectrum of surface charge via adjustment of the thickness of the outermost silica shell from 20 to 40 nm, which sets the isoelectric point (IEP) in the range of 5.1–8.6. Subsequently, the silica shell significantly extends the product's stability and utilization windows due to the controlled surface charge and affinity between the particle surface and the dispersion medium. The developed multilayered core–shell microspheres and the method of synthesis have great potential for various applications that require sophisticated control of surface properties.