Quantum yields of active oxidative species formed on TiO2 photocatalyst

The quantum yield of hydroxyl radical (. OH) production during TiO2 photocatalysis was estimated to be 7 x 10(-5) in aqueous solution by means of a method using terephthalic acid as a fluorescence probe. This value is much lower than the quantum yield of ordinary photocatalytic reactions (similar to 10(-2)). Conversely the quantum yield of hole generation estimated by iodide ion oxidation was equivalent (5.7 x 10(-2)) to that of ordinary photocatalytic reactions. This implies that oxidative reactions on TiO2 photocatalyst occur mainly via photogenerated holes, not via . OH. (C) 2000 Elsevier Science S.A. All rights reserved.