Patent ID: 8404617

Claim:
A photocatalyst composition comprising 50% by mass or more of a photocatalyst material comprising, as its major component, a tungsten oxide powder having an average grain diameter of 0.5 μm or less and mainly containing monoclinic crystals, excited by a light source which emits light having a wavelength of 430 to 500 nm, with a peak wavelength of 460 nm+10 nm, wherein the photocatalyst material has a decomposition ability of 50% or more which is determined by the following equation based on the following test: [Test for decomposition ability] 1 g of a tungsten oxide powder and 20 ppm of acetaldehyde (amount A) are poured into a 3-liter glass container, and acetaldehyde (amount B) is measured after light having a peak wavelength of 460 nm+10 nm is irradiated to the mixture for 2 hours to measure the decomposition ability (%): Decomposition ability (%)=[(acetaldehyde amount A −acetaldehyde amount B )/acetaldehyde amount A]× 100.