Fabrication of SiO2/Al2O3 Composite-Coated TiO2 by Pulsed Chemical Vapor Deposition and Its Applications

Surface modification is required for various applications of titanium dioxide (TiO2) to suppress the photoactivity of TiO2. In this work, a composite SiO2/Al2O3 film was successfully deposited onto TiO2 particles by pulsed chemical vapor deposition. The composite film was particularly dense and uniform, as it was constituted by the 4.17 nm SiO2 and 1.62 nm Al2O3 amorphous films. The photocatalytic process with coated TiO2 was investigated. The enhanced rate of carrier recombination in SiO2/Al2O3- coated TiO2 was the main cause of inhibited photoactivity, which was mainly contributed by the inner SiO2 film. TiO2/SiO2 and TiO2/SiO2/Al2O3 presented outstanding pigmentary properties. Compared to naked TiO2, TiO2/SiO2/Al2O3 was more conducive to the weatherability of polyvinyl chloride and waterborne paints, owing to the suppressed photoactivity of the SiO2 film and the increased optical absorption of the outer Al2O3 film. The pulsed chemical vapor deposition showed promising industrial application potential for TiO2 surface modification.