Photocatalysis

Photocatalysis is catalysis initiated or driven by light. Absorbed photons create excited states or charge carriers that enable chemical reactions.

Photophysical processes: Processes in which light absorption changes a molecule’s or material’s electronic state without necessarily changing its chemical identity. Photon absorption creates the excited states that can initiate photocatalytic reactions.
Photocatalytic water splitting: The use of light-driven catalysts to split water into hydrogen and oxygen. It applies photocatalytic charge transfer to solar-fuel production.
Semiconductor: A material whose electrical conductivity lies between that of a conductor and an insulator and can be altered by energy or impurities. Many photocatalysts are semiconductors that generate mobile charges when illuminated.
Thermal catalysis: Catalysis driven primarily by heat rather than by photogenerated excited states or charge carriers. It provides the clearest comparison for separating light-driven activation from heat-driven reaction.
Electron–hole pair: A negatively charged electron and positively charged vacancy created together when a semiconductor absorbs sufficient energy. These charge carriers drive oxidation and reduction at semiconductor photocatalyst surfaces.
Photocatalytic carbon dioxide reduction: The light-driven conversion of carbon dioxide into reduced products such as carbon monoxide or fuels. It uses photogenerated electrons to convert a stable greenhouse gas into chemical products.
Photochemistry: The study of chemical changes initiated by the absorption of light. Photocatalysis is a catalytic subset of light-driven chemistry.
Electrocatalysis: Catalysis in which an applied electrical potential drives reactions at an electrode. It supplies charges electrically, whereas photocatalysis can generate them through light absorption.
Band gap: The energy difference between a material’s valence band and conduction band. Its size sets which photons can excite charge carriers in a semiconductor photocatalyst.
Photocatalytic air purification: The use of light-activated catalysts to oxidize airborne contaminants. It applies surface-generated reactive species to break down pollutants in air.

Linked from 15 pages