Abstract: Titanium oxide-based photocatalysts which contain a metal halide in titanium oxide and which are prepared from titanium oxide and/or its precursor, which may optionally be heat treated, by contact with a reactive gas containing a metal halide of the formula MXn or MOXn (wherein M=a metal, X=a halogen, and n=an integer) with heating stably develop a high photocatalytic activity with visible light irradiation. The photocatalysts may subsequently be stabilized by contact with water or by heat treatment, and/or promoted by contact with a heteropoly acid and/or an isopoly acid so as to include a metal complex in the titanium oxide. Photocatalysts prepared in this manner exhibit novel ESR features. The present invention also provides methods for preparing these photocatalysts, a photocatalyst dispersion and a photocatalytic coating fluid containing such a photocatalyst, and photocatalytic functional products and methods for their manufacture using the photocatalyst.

Abstract: A titanium oxide-based photocatalyst which can exhibit excellent photocatalytic properties in response to visible light while maintaining its inherent activity in response to ultraviolet light and which is suitable for mass production contains bismuth as a first additional metal component and at least one metal element selected from silicon, zirconium, aluminum, and hafnium as a second additional metal component in titanium oxide. The Bi/Ti atomic ratio is preferably at least 0.0001 and at most 1.0, the atomic ratio of the second additional metal to Ti is preferably at least 0.0001 and at most 0.8, and a portion of bismuth is preferably present in the form of lower valence (Bi2+ or Bi0). The presence of lower valence bismuth can be ascertained by XPS analysis.

Abstract: A highly active titanium oxide photocatalyst of the type responsive to visible light is prepared by subjecting a titanium (hydr)oxide raw material obtained by neutralizing an acidic titanium compound in ammonia or an amine under conditions such that the final pH is 7 or below to heat treatment in an atmosphere containing a hydrolyzable compound followed by contact with water and additional heat treatment at a temperature of at least 350° C. The resulting titanium oxide photocatalyst comprises titanium oxide with a specific surface area of at most 120 m2/g and with the amount of surface hydroxyl groups being at least 600 ?eq/g. Preferably the density of surface hydroxyl groups is at least 8 ?eq/m2, and the ratio of the amount of terminal type hydroxyl groups (T) to the amount of bridge type hydroxyl groups (B) in the surface hydroxyl groups satisfies T/B?0.20. This titanium oxide photocatalyst has an ESR spectrum having two types of triplet signal for which the g values of the main spectra are 1.993-2.

Abstract: A photocatalytic composite material having a photocatalytic titanium oxide film on the surface of a substrate is produced by a CVD method in which TiCl4 vapor is reacted with water vapor. The TiCl4 vapor and the water vapor are injected into a vapor deposition chamber (9) through nozzles (5) and (6), respectively, such that the resulting two injected vapor streams meet before reaching the substrate, thereby mixing the two vapors. Within 3 seconds after this mixing, the mixed vapors are brought into contact with a substrate (1) which is moving in one direction. Preferably the TiCl4 vapor is injected in a reverse direction with respect to the direction of movement of the substrate through a multi-orifice nozzle (5), while the water vapor is injected through a slit nozzle (6) disposed at a smaller angle with respect to the substrate.

Abstract: Titanium oxide-based photocatalysts which contain a metal halide in titanium oxide and which are prepared from titanium oxide and/or its precursor, which may optionally be heat treated, by contact with a reactive gas containing a metal halide of the formula MXn or MOXn (wherein M=a metal, X=a halogen, and n=an integer) with heating stably develop a high photocatalytic activity with visible light irradiation. The photocatalysts may subsequently be stabilized by contact with water or by heat treatment, and/or promoted by contact with a heteropoly acid and/or an isopoly acid so as to include a metal complex in the titanium oxide. Photocatalysts prepared in this manner exhibit novel ESR features. The present invention also provides methods for preparing these photocatalysts, a photocatalyst dispersion and a photocatalytic coating fluid containing such a photocatalyst, and photocatalytic functional products and methods for their manufacture using the photocatalyst.

Abstract: A photocatalytic composite material having a high activity and good durability is produced by coating the surface of a substrate with a continuous film of titanium oxide by vapor deposition from titanium tetrachloride. In the case of a substrate which is a mass of inorganic fibers such as glass cloth, the individual fibers or filaments in the mass are coated with titanium oxide. The vapor deposition is performed by contacting the substrate, such as a mass of inorganic fibers, which has been heated to 100-300° C., with a mixture of distilled pure titanium tetrachloride vapor and water vapor to form a film of a titanium oxide precursor on the surface of the substrate. Then, the substrate is heated at 300-600° C. in an oxidizing atmosphere, resulting in the formation on the substrate surface of a continuous film of a photocatalyst having a high activity and good adhesion to the substrate and comprising crystalline titanium oxide with an average crystallite diameter of 50 nm or smaller.