Radical species production during ozonation of illuminated titanium dioxide suspensions

摘要

The process of heterogeneous photocatalysis involves the radiation of a semiconductor such as titanium dioxide (TiO_2) with ultraviolet light behow 390 nm. The radiation stimulates valence band eletrions in the TiO_2 producing electron/hole pairs. It has been suggested that positively charged holes ultimately react with water consituents suh as OH~- to produce hydroxyl radicals (OH). Excess conduction band electrons react with O_2 to produce super-oxide ions which disproportionate to form radicals.