以苯酚的光催化降解为模型反应，研究了锐钛矿相和金红石相二氧化钛纳米晶（7～40nm）的光催化活性．与市售的氧化钛相比，两种晶相的纳米氧化钛均有很高的光催化活性，锐钛矿相氧化钛对苯酚的深度矿化有更高的选择性．TiO2吸附的水及羟基会降低氧化钛的光催化活性．由于粒径减小使氧化钛的吸收带边界蓝移，粒径小的氧化钛有更高的催化活性，粒径＜15nm时，显示出量子尺寸效应．
In the present study, particulate suspensions of nanosized(particle size less than 10nm) anatase and rutile TiO2 under UV irradiation in a loop
photoreactor catalyzed the oxidation of a typical organic contaminant: phenol. Both nanosized anatase and rutile TiO2 have a much higher photocatalytic
activity than bulk TiO2 (particle size more than 100nm), however, anatase shows a higher selectivity for complete mineralization: the concentration of
p-quinone as intermediate of this photocatalytic reaction is at lower level than those of rutile. Species adsorbed by titanium dioxide such as H2O and OH
play a significant role in the photodegradation of phenol as well as particle size . With the decrement of particle size especially less than 15nm,
the photocatalytic activity of TiO2 increases dynamically.
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