TiO₂/SiO₂ 複合ナノ粒子の水熱合成とその光触媒性能

抄録

Anatase (TiO₂)/silica (SiO₂) composite nanoparticles over the compositional range of SiO₂=0-70.9 mol% were directly formed from acidic precursor solutions of TiOSO₄ and tetraethylorthosilicate by hydrolysis under mild hydrothermal conditions at 200°C. With increasing SiO₂ content, the specific surface area of the as-prepared composite nanoparticles increased from 109 (SiO₂=0 mol%) to 277 m²/g (SiO₂=70.9 mol%), which was associated with an increase in the amorphous phase content. The composite nanoparticles with a unique microstructure, i.e., anatase crystallites 14-16 nm in size that exist separately due to the presence of an amorphous silica phase in the TiO₂/SiO₂ interface, showed enhanced photocatalytic activities for the decomposition of methylene blue (MB) in aqueous solution and better removal of NO gas in comparison with pure anatase-type TiO₂. The highest photoactivity was obtained when the SiO₂ content in the composites was 25.1 mol% for MB decomposition and 48.2 mol% for NO oxidation.