A new photocatalyst, known as nitrogen-doped TiO2
(TiO2-xNx), yielding high reactivity
under visible light irradiation, together with high
potential for mass-productivity, has been developed
by using a highly time-efficient development technique
that combines compu-tational materials design with
experimental syntheses. Under visible light irradiation,
TiO2-xNx films and powders exhibit
significant advantages over commercially-available
TiO2 in terms of optical absorption and
photocatalytic decomposition rates with respect to
gaseous acetaldehyde and toluene, etc. The active
wavelength range of TiO2-xNx
(below 520 nm) covers a wider irradiation energy range
for white fluorescent and incandescent light than
that of TiO2. As a result, TiO2-xNx
exhibits a photodecomposition rate for gaseous acetaldehyde
that is more than 5 times higher than that of TiO2
under interior illumination (300-600 lux). It also
exhibits significant antibacterial properties. TiO2-xNx
is therefore a promising photocatalytic material,
and it possesses other desirable features; it shows
highly reproducible photocatalytic activity, it has
a potential for mass-production, and it is environmentally
benign (no toxic ingredients). Further development
of this material is now underway, so it should be
available to contribute to the human environment by
reducing indoor VOCs (Volatile Organic Compounds)
in the very near future.
可視光下での高い反応速度と生産性を兼ね備えた新しい光触媒，窒素ドープ酸化チタン (TiO2-xNx)
を開発した。開発時には，第一原理計算と実験を併行させることにより，高効率な開発を実現した。TiO2-xNx薄膜や粉末は，可視光照射下におけるアセトアルデヒドやトルエンなどの揮発性有害物質の分解速度において，市販のTiO2光触媒よりも高い値を示す。この光触媒は波長520nm以下の可視光を吸収するため，蛍光灯や白熱灯の吸光率が高く，例えば300-600ルクスの照度下でTiO2の5倍以上のアセトアルデヒド分解速度を示す。また蛍光灯照射下での抗菌性も示す。この材料は再現性，生産性，毒性物質を含まない，という観点で実用化への障壁が比較的小さく，現在商品化が進められている。近い将来，可視光触媒が室内VOCの抑制などで，人間の居住環境において不可欠になることを期待する。
