Properties of O 2 • - and OH • Formed in TiO 2 Aqueous Suspensions by Photocatalytic Reaction and the Influence of H 2 O 2 and Some Ions

We have investigated the effect of H2O2 on the behavior of O2•- and OH• produced in photocatalysis of aqueous TiO2 suspensions by means of luminol chemiluminescence probing and terephthalic acid fluorescence probing, respectively. The reduction of O2 by photoinduced conduction band electrons (e-) was increased by the addition of H2O2, since the consumption of photoinduced valence band holes (h+) in the oxidation of H2O2 caused the repression of e-−h+ recombination. After the end of the light irradiation, the amount of O2•- decreased based on the fractal-like kinetics at the heterogeneous surface of the TiO2 particle. The decay process might be caused by trapped h+, which cannot react with water and then…