二氧化钛纳米晶的光催化活性研究

Photocatalytic Activity of Nanosized TiO_2

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 contaxninant: 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 paxticle size especially less than 15nm, the photocatalytic activity of TiO2 increases dynamicajly.