Photocatalysis is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible light (400 – 750 nm) or infrared radiation (750 – 2500 nm). A catalyst is not changed or consumed in the overall chemical reaction.
There are various materials that show photocatalytic capability, and titanium dioxide (TiO2) is said to be the most effective.
When a photocatalyst is exposed to light in the presence of water vapor, two highly reactive substances are formed: hydroxyl radicals [OH] and a superoxide anion [O2-1]. It allows for the oxidation of airborne Volatile Organic Compounds (VOCs) and toxic organic matter into carbon dioxide and water at room temperature when exposed to light. It does not require any advanced technology to operate effectively.