Coating and photochemical properties of calcia-doped ceria with amorphous silica by a seeded polymerization technique

Calcia doped ceria is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of its excellent UV light absorption properties and its low catalytic ability for the oxidation of organic materials is superior to undoped ceria. In order to reduce the oxidation catalytic activity further, calcia doped ceria was coated with amorphous silica by means of a seeded polymerization technique. The silica shell was confirmed using scanning electron microscopy, TEM, XPS and FT-IR. Silica coating by seeded polymerization was much more efficient in the reduction of the oxidation catalytic activity without loss of the UV-shielding ability, than coating by acid hydrolysis of a sodium silicate solution.