Photocatalyzed

Photocatalyzed refers to a process where a chemical reaction is initiated or accelerated by light in the presence of a catalyst. The catalyst, known as a photocatalyst, absorbs photons from the light source and enters an excited state. This excited state allows the photocatalyst to facilitate the reaction by interacting with other molecules. The most common photocatalyst is titanium dioxide (TiO2), which is widely used in applications like self-cleaning surfaces and air purification.

The mechanism typically involves the photocatalyst absorbing light energy equal to or greater than its band gap. This absorption generates electron-hole pairs within the material. The excited electron can then reduce adsorbed species, while the hole can oxidize them. These generated reactive oxygen species, such as hydroxyl radicals (•OH) and superoxide radicals (O2•−), are highly reactive and can break down organic pollutants, kill microorganisms, or otherwise induce chemical transformations.

Photocatalyzed processes are considered environmentally friendly as they often utilize light as the energy source and can degrade harmful substances into less toxic or inert products. Applications extend beyond environmental remediation to areas like water splitting for hydrogen production, organic synthesis, and photodynamic therapy in medicine. The efficiency of photocatalysis depends on factors such as the light intensity and wavelength, the properties of the photocatalyst, and the surface area available for reaction.