Preparation and properties of silica-modified nano-titania by coating precipitation method

Titania nano-particles coated with silica were prepared by the coating precipitation method,which sodium silicate was used as the coating agent and sulfuric acid as the neutralization agent.The prepared samples were characterized by FT-IR,XRD,TEM and X-ray energy dispersive spectrum(EDS).It was inferred that the Ti—O—Si bond was formed at the interface of the coating layer and TiO2 particles.The addition of silica in TiO2 particle could effectively decrease the formation of rutile phase.TEM images demonstrated that TiO2 coated with silica has smaller particle size,uniform size distribution and polished surface.The specific surface area experiment showed that the specific surface area of titania nano-particles coated with silica reduced with increasing of m(SiO2)∶m(TiO2).When content of silica is 2.39%,the specific surface area become highest value.In comparison with pure TiO2 nanoparticles,the silica-modified TiO2 nanoparticles exhibited better photocatalytic activities,and the optimal activities were obtained as they were treated at the calcinations temperature of 600℃.