US Patent 7300634 - CNT field emission for air purification

http://www.freepatentsonline.com/7300634.html

Ultraviolet light is used in various purification systems. Many of these systems use fluorescent lamps as the source of the ultraviolet light which have limited life expectancies, take time to fully turn on and can be toxic to the environment. This patent form Nano-proprietary teaches an alternative using field emission cathodes (such as carbon nanotubes) in ultraviolet sources for air or water purification. Claim 1 reads:

1. A photocatalytic cleaner for air or water, comprising: a photocatalytic material coating a substrate; an anode, positioned a predetermined distance from the substrate, comprising a phosphor adapted to emit ultraviolet light in response to bombardment by electrons; and a field emission cathode, positioned a predetermined distance from the anode, operable for emitting electrons in response to an electric field.