Photocatalyst can produce more than 99% of resolving results to formaldehyde and organic matter under visible light. Because this course adopts contacting catalysis and oxidation principle, the catalyst composition plays a medium role, therefore the photocatalyst composition has no change, so does not need any treatment for using long time. Features: 1) Main material: foamed metal, photocatalyst, nickel 2) Utility function that the world initiates: can be water-washed, the effect after water-wash will not decrease 3) Applications: appliances that we can use filter screens such as air conditioner, and filter