Photocatalyst element structure, ultraviolet radiation air purification system, photocatalyst sheet, and method of manufacturing photocatalyst sheet

1. A photocatalyst element structure comprising:

a photocatalyst element including a flat photocatalyst sheet and an undulating photocatalyst sheet overlapped on the flat photocatalyst sheet, wherein

the flat photocatalyst sheet and the undulating photocatalyst sheet include a porous titanium foil having a non-periodic spongy structure impregnated with anatase titanium dioxide particles.

2. The photocatalyst element structure according to claim 1 , comprising a plurality of the photocatalyst elements arranged so that the flat photocatalyst sheet and the undulating photocatalyst sheet alternate.

3. The photocatalyst element structure according to claim 1 , wherein the porous titanium foil is flexible.

4. The photocatalyst element structure according to claim 1 , wherein the porous titanium foil is formed by subjecting a titanium foil to etching processing in non-periodic patterns from one or both surfaces of the titanium foil.

5. The photocatalyst element structure according to claim 1 , wherein the undulating photocatalyst sheet has substantially parallel and alternating ridges and trenches that extend in one direction, and the photocatalyst element being rolled in a centrally hollow cylindrical shape so that the ridges and the trenches of the undulating photocatalyst sheet extend in a direction of a central axis of the cylindrical photocatalyst element.

6. The photocatalyst element structure according to claim 5 , wherein the undulating photocatalyst sheet is located on an outer periphery of the cylindrical photocatalyst element.

7. An ultraviolet radiation air purification system comprising:

a casing having an air inlet and an air outlet;

a photocatalyst element structure that is arranged inside the casing for purifying air inside the casing; and

an ultraviolet radiation source that irradiates ultraviolet radiation to activate a photocatalyst of the photocatalyst element structure, wherein

the photocatalyst element structure includes a photocatalyst element including a flat photocatalyst sheet and an undulating photocatalyst sheet overlapped on the flat photocatalyst sheet, and

the flat photocatalyst sheet and the undulating photocatalyst sheet include a porous titanium foil having a non-periodic spongy structure impregnated with anatase titanium dioxide particles as the photocatalyst.

8. The ultraviolet radiation air purification system according to claim 7 , comprising a plurality of photocatalyst elements arranged so that the flat photocatalyst sheet and the undulating photocatalyst sheet alternate.

9. The photocatalyst element structure according to claim 7 , wherein the porous titanium foil is flexible.

10. The ultraviolet radiation air purification system according to claim 7 , wherein the porous titanium foil is formed by subjecting a titanium foil to etching processing in non-periodic patterns from one or both surfaces of the titanium foil.

11. The ultraviolet radiation air purification system according to claim 7 , wherein the undulating photocatalyst sheet has substantially parallel and alternating ridges and trenches that extend in one direction, and the photocatalyst element being rolled in a centrally hollow cylindrical shape so that the ridges and the trenches of the undulating photocatalyst sheet extend in a direction of a central axis of the cylindrical photocatalyst element.

12. The ultraviolet radiation air purification system according to claim 11 , wherein the undulating photocatalyst sheet is located on an outer periphery of the cylindrical photocatalyst element.

13. The ultraviolet radiation air purification system according to claim 7 , wherein

the photocatalyst element being rolled in a centrally hollow cylindrical shape, the ultraviolet radiation source being arranged inside a hollow portion of the cylindrical photocatalyst element, one end of the cylindrical photocatalyst element being closed with a closing member so that air does not pass through that end in the hollow portion and other end of the cylindrical photocatalyst element being open so that air entering into the hollow portion through walls of the photocatalyst element is discharged through that end, and

the ultraviolet radiation air purification system further comprising a guide member arranged inside the casing to guide air entering the casing onto the photocatalyst element structure.

14. The ultraviolet radiation air purification system according to claim 7 , wherein the ultraviolet radiation source includes one or both of a sterilization lamp with a central wavelength of 254±10 nanometers and an ozone generation lamp with a central wavelength of 185±10 nanometers.