SiO2 coated platy TiO2 designed for noble UV/IR-shielding materials

Abstract

SiO2 coated platy TiO2 (S-pTi) was prepared as a noble UV/IR(Ultraviolet/Infrared)-shielding material by a modified Stöber method. S-pTi consists of a dense and uniform SiO2 shell onto platy TiO2 (pTi) core, and the thickness of SiO2 shell layer was coated about 8–20 nm by tuning SiO2 coating amount. The zeta-potential of S-pTi was decreased from −12 to −32 mV with increasing amounts of coated SiO2, indicating the improvement of dispersibility between the particles. The UV-shielding ability of S-pTi was improved by enhancing UV absorption of the SiO2 coating layer onto pTi and thus the photocatalytic activity was suppressed effectively. Compared to nanosized TiO2(nTi), S-pTi showed higher UV absorption at the shorter wavelength and exhibited higher IR reflectance because of high reflective index and the crystal shape and size of pTi to reflect the IR effectively under its wide shielding area. These results can contribute to the prevention of harmful UV and the maintenance of a cool environment from IR heat source as noble UV/IR-shielding materials on the skin.