Preparation of novel TiO_2-silica filter photocatalyst derived from titanium alkoxy-diolate precursor

摘要

Commercially available TiO_2 (Degussa, P-25) is well-known as a highly active photocatalyst. However, in order to work as a photocatalyst, TiO_2 must be dispersed onto a substrate without any binders but this still remains very difficult. We thus attempted to develop a novel TiO_2 system with high photocatalytic activity. TiO_2 anchored silica fibers (TAS) were prepared by chemical vapor deposition using titanium(IV) ethoxide and 1,3-butanediol. The content of TiO_2 in TAS was varied from 0.5 to 5 mass%. It was observed that the surface of TAS was covered with anatase TiO_2 particles 5-10 nm in diameter. TAS shows higher activity at a lower loading amount compared to P-25. Measurement of the acetaldehyde decomposition rate constant of P-25 and TAS carrying 2 mass% of titanium oxide under ultraviolet irradiation showed a value for TAS that was 1.4 times that of P-25. TAS showed a solid acidity amount higher than the P-25 in NH3-TPD measurements. It was considered that some Si species from the silica fibers migrated into the TiO_2 layer by calcination, increasing the solid acidity of TAS. As a result, the adsorption of acetaldehyde increased, and the photocatalyst activity improved.