Photocatalytic reactivity for O2•- and OH• radical formation in anatase and rutile TiO2 suspension as the effect of H2O2 addition

Effect of crystalline structure, anatase and rutile, on the production of OH(center dot) and O(2)(center dot-) by TiO(2) photocatalytic reaction was investigated. The OH(center dot) radical free from the TiO(2) surface was monitored by the fluorescence intensity of 2-hydroxyl terephthalic acid produced by the reaction with terephthalic acid. Superoxide radical was detected by the chemiluminescence probe method with luminol. Formation rate of OH(center dot) with rutile photocatalysts was significantly lower than that with anatase photocatalysts. By the addition of H(2)O(2), the formation rate of OH(center dot) was significantly increased for rutile and for anatase mixed with rutile by 10-20%, while pure anatase showed an opposite tendency. We suggest that the adsorption structure of H(2)O(2) on the rutile TiO(2) surface is preferable to produce OH(center dot). In photocatalytic production of O(2)(center dot-), rutile surpassed anatase in stabilizing the produced O(2)(center dot-). On H(2)O(2) addition, anatase surpassed rutile in the photocatalytic activity to produce O(2)(center dot-) from H(2)O(2.) (C) 2007 Elsevier B.V. All rights reserved.