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Toyama-shi, Japan

Takahashi T.,The University of Shimane | Tokuda K.,Omikenshi Co. | Miyamoto Y.,Omikenshi Co. | Sanbayashi M.,Showa Titanium Co.
Textile Research Journal | Year: 2013

When titanium dioxide is irradiated with light, electrons and electron holes are generated. These exert strong reductive and oxidative forces, which induce reaction with atmospheric water and oxygen, generating reactive oxygen species such as hydroxyl radicals and superoxide anions. These substances not only kill miscellaneous bacteria, but also effectively aid in the decomposition of odorous substances. In rayon fibers containing titanium dioxide photocatalyst, weight reduction occurring by enzymatic treatment was applied to effectively activate the photocatalyst, even though the catalyst was added in limited amounts. Enzymatic treatment using cellulase effectively roughened the surface of the rayon fibers and largely improved the antibacterial activity. When the amount of TiO2 added was 2.5 wt% and the weight reduction ratio of the fibers reached 4.2% or 7.1%, the antibacterial activity was enhanced so strongly that viable bacteria were not detected at all. However, when the weight reduction ratio of the fibers increased to 10.5%, the antibacterial activity decreased. Further, the deodorizing ability of the fibers against gaseous ammonia improved significantly by the enzymatic treatment. In the case of fibers containing 2.5 wt% of TiO2, samples before enzymatic treatment showed an odor residual percentage of 28.4%, while after treatment, a much lower figure of 0.25% was obtained. However, although the tensile strength of the fiber decreased because of the weight reduction treatment, the fibers exhibited a tensile strength of 1.63 cN/dtex even after a weight reduction of 7.1 wt% (the tensile strength before weight reduction treatment was 2.49 cN/dtex). Thus, the application of an appropriate weight reduction finish to rayon fibers containing titanium dioxide was very effective in enhancing the photocatalytic activity of the material. Presumably, the action of the enzyme during the treatment dissolved the cellulose present on the fiber surface, which exposed the titanium dioxide particles embedded within the fibers that were proximal to the surface. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. Source

Yu H.,Yamanashi University | Irie H.,Tokyo University of Science | Shimodaira Y.,Showa Denko K.K. | Hosogi Y.,Showa Titanium Co. | And 4 more authors.
Journal of Physical Chemistry C | Year: 2010

We have prepared a TiO2-based novel visible-light-sensitive photocatalyst, in which Fe(III) species were grafted on a rutile TiO2 surface (denoted as Fe(III)/TiO2). With use of X-ray absorption fine structure analysis, the grafted iron species were determined to be in the 3+ state and adopt an amorphous FeO(OH)-like structure. Fe(III)/TiO2 displayed optical absorption in the visible light range over 400 nm, which was assigned to the interfacial charge transfer from the valence band of TiO 2 to the surface Fe(III) species. Its photocatalytic activity was evaluated by the decomposition of gaseous 2-propanol under visible light (400-530 nm), which revealed a high quantum efficiency (QE) of 22%. Monochromatic light experiments indicated that the effective wavelength region was extended as far as 580 nm while maintaining a QE of greater than 10%. On the basis of the analogy to Cu(II)-grafted TiO2 photocatalyst (Irie, H.; et al. Chem. Phys. Lett. 2008, 457, 202), we speculate that the high performance of the present photocatalyst is derived from the photoproduced holes that are generated in the valence band of TiO2 and contribute to the oxidative decomposition of 2-propanol, and the catalytic reduction of oxygen (presumably multielectron reduction) by photoproduced Fe(II) species on TiO 2. © 2010 American Chemical Society. Source

Sugishita N.,Showa Titanium Co. | Kuroda Y.,Showa Titanium Co. | Ohtani B.,Hokkaido University
Catalysis Today | Year: 2011

Anatase titania (TiO2) particles were synthesized from titanium(IV) chloride (TiCl4) and oxygen (O2) through an improved gas-phase reaction process under rapid heating and rapid quenching conditions. The obtained particles were decahedral-shaped highly crystalline particles with specific surface area of 5-40 m2 g-1. These particles exhibited a level of photocatalytic activity higher than the representative commercial TiO2 photocatalysts for oxidative decomposition of acetic acid in an aqueous solution and acetaldehyde in air. Their higher level of activity is considered to be due to a combination of their moderate specific surface area and high crystallinity. © 2010 Elsevier B.V. All rights reserved. Source

Qiu X.,Tokyo University of Science | Miyauchi M.,Tokyo Institute of Technology | Sunada K.,Tokyo University of Science | Minoshima M.,University of Tokyo | And 8 more authors.
ACS Nano | Year: 2012

Photocatalytic TiO 2 powders impart ultraviolet light-induced self-cleaning and antibacterial functions when coated on outdoor building materials. For indoor applications, however, TiO 2 must be modified for visible-light and dark sensitivity. Here we report that the grafting of nanometer-sized Cu xO clusters onto TiO 2 generates an excellent risk-reduction material in indoor environments. X-ray absorption near-edge structure using synchrotron radiation and high-resolution transmission electron microscopic analyses revealed that Cu xO clusters were composed of Cu I and Cu II valence states. The Cu II species in the Cu xO clusters endow TiO 2 with efficient visible-light photooxidation of volatile organic compounds, whereas the Cu I species impart antimicrobial properties under dark conditions. By controlling the balance between Cu I and Cu II in Cu xO, efficient decomposition and antipathogenic activity were achieved in the hybrid Cu xO/TiO 2 nanocomposites. © 2011 American Chemical Society. Source

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