OSAKA Titanium and Sumitomo Metals Develop Highly-Active Visible Light Responsive Photocatalysts
-Performance Improved by Approximately Five Times Compared to Conventional Products

OSAKA Titanium Technologies Co., Ltd. (President - Mr. Masaaki Tachibana: Head office - Amagasaki, Hyogo Prefecture) and the Corporate Research & Development Laboratory of Sumitomo Metal Industries, Ltd. (General Manager-Mr. Takahisa Miyake) have jointly developed a new type of highly-active visible light responsive ("the new product")photocatalyst.

This new product shows about five times higher visible light photocatalytic performance than conventional products for decomposition of volatile organic compounds (VOCs) such as acetoaldehyde and toluene. Moreover, it can decompose odoriferous substances such as ammonia. Because of its performance, the new product may be able to bring about rapid spread of visible light responsive photocatalysts in the various fields. Accordingly, OSAKA Titanium Technologies Co., Ltd. is planning to start mass production of the new product during the current fiscal year in order to meet the expected growth in demand.

1. Background and objective of development
Photocatalysts that absorb light and decompose organic matters using its energy have drawn attention as eco-materials with various environmental purification functions. The current market size of photocatalysts is said to be approximately 90 billion yen, most of which is estimated to be for the outdoor use of UV-type photocatalysts. Going forward, the market is expected to reach about 400 billion yen by 2015 as a result of an increase in the application of visible light responsive photocatalysts indoors or under illumination during the night when UV light is limited. Under these circumstances, there has been a need for a dramatic improvement in the performance of visible light responsive photocatalysts.

2. Features of the product
(1) The new product performs about five times higher than conventional products (visible light responsive types) in terms of the activity for decomposition of volatile organic compounds (VOCs) such as acetoaldehyde and toluene under visible light irradiation. Moreover, it can also decompose odoriferous substances such as ammonia.

(2) Under fluorescent light irradiation, the new product can decompose acetoaldehyde and toluene in concentration of only a few parts per million (ppm) completely to carbon dioxide. Moreover, under irradiation at low illumination of several hundred lux, super-hydrophilicity has been recognized. As attached water molecules on the photocatalyst surface do not transform into water drops but rather form an extremely thin film, the effects of defogging and sweeping away dirt can be expected.

(3) It is difficult with the conventional products to make visible light and UV light photocatalytic activities compatible with each other. The new product has the unique structure for visible light absorption, based on the combination of titanic oxide with other metal oxides. As a result, it has succeeded in maintaining a high level of photocatalytic activities both under visible light irradiation and under UV light irradiation.

(4) The product is available not only in powder form but also in a sol which comprises an aqueous dispersion of nano-size particles dispersed therein. By applying sols directly to products or converting them into coating materials if necessary, photocatalysis can be supported on the surface of products.

3. Future development
OSAKA Titanium is already engaged in the production and sale of visible light responsive photocatalysts. These products are sold to manufacturers of interior materials in Japan, who use the photocatalysts for anti-VOC, antibacterial, or deodorizing purposes for schools, hospitals, public facilities, food processing factories, shops, and general housing. In addition, these products have begun to be used in China and South Korea.
OSAKA Titanium and Sumitomo Metals anticipate that, because of the significant improvement in the of visible light photocatlytic performance, the photocatalysts will begin to be applied on a full scale in various materials and uses that include housing interior materials, construction materials, and interior materials of automobiles. OSAKA Titanium plans to start mass production of the product during the current fiscal year in order to meet future demand growth.

[Terms]
Photocatalysts
Materials that generate photocatalysis under light irradiation. They accelerate photoreaction but do not change themselves. Titanic oxide is known as a representative photocatalyst. Photocatalysts show two functions caused by absorbing light: strong oxidative decomposition and high super-hydrophilicity. The oxidative decomposition function can be used for deodorizing, antibacterial effects, and the decomposition and disposal of toxic materials. The super-hydrophilicity effect is expected to result in defogging and sweeping away of dirt.

(Photocatalyst) activities
Performance of a photoreaction as photocatalysis when light is absorbed. Generally, it is measured by the speed of decomposition of targeted materials (organic substances.)

Visible light responsive photocatalysts
Photocatalysts that perform a photoreaction under visible light irradiation (wavelength >380nm.)They function even indoors and under nighttime illumination in conditions where conventional UV-type photocatalysts are unable to function. Thus full-scale application of the new type of photocatalyst is anticipated to significantly expand the market for photocatalysts.

Volatile organic compounds (VOCs)
Formaldehyde, acetoaldehyde, toluene, etc. These materials tend to cause the "sick house syndrome."