Role of synthesis method and particle size of nanostructured TiO2 on its photoactivity
Role of synthesis method and particle size of nanostructured TiO2 on its photoactivity
复制标题
DOI：
10.1006/jcat.2002.3783
复制
发表时间：
2002-12-10
影响因子：
7.3
通讯作者：
Biswas, P
中科院分区：
文献类型：
--
作者：
Almquist, CB;Biswas, P
采用不同方法制备的TiO（2），得到了粒径为5 ~ 165 μ m的纳米TiO 2粉体。使用两种方法制备粉末：（i）火焰气溶胶方法，其中在火焰中在有机钛前体的氧化（燃烧）中合成TiO（2）的纳米颗粒，和（ii）煅烧市售纳米结构TiO（2）（Ishihara ST-01，5 nm，原样）。为了比较，Degussa P25和Aldrich TiO 2粉末也按原样使用。采用XRD、BET比表面积分析、UV-Vis吸收光谱、苯酚光氧化速率等方法对TiO 2粉体进行了表征。基于TiO_2光催化降解有机物的机理，建立了一个模型，用以解释粒径对TiO_2光催化降解水中有机物的表观光活性的影响。该模型被用来解释四组不同的光活性实验与TiO（2）粉末的实验数据的趋势。本研究的结果阐明了颗粒大小对光活性的强烈影响。粒径对光吸收和散射效率以及电荷载流子动力学的影响在粒径小于25 nm时主导了TiO（2）的表观光活性，并且在本研究中使用TiO（2）粉末进行的所有组的光催化实验中存在25至40 nm的最佳粒径。最佳粒径是有效粒径对光吸收和散射效率、电荷载流子动力学和表面积的竞争效应的结果。(C)2002 Elsevier Science（美国）。
TiO(2) prepared by different methods was used to obtain anatase powders with particle sizes ranging from 5 to 165 rim. Powders were prepared using two methods: (i) a flame aerosol process in which nanoparticles of TiO(2) were synthesized in a flame on oxidation (combustion) of an organotitanium precursor, and (ii) calcination of commercially available nanostructured TiO(2) (Ishihara ST-01, 5 nm, as received). For comparison, Degussa P25 and Aldrich anatase TiO(2) powders were also used as received. The TiO(2) powders were characterized using XRD to determine crystal phase and crystal size, BET surface area analyses, uv-vis absorbtion spectroscopy to determine the band gap, and experiments in which the photoxidation rate of phenol in water was used as a measure of photoactivity. A model was developed based on the mechanistic steps in photocatalysis to elucidate the role of particle size on the apparent photoactivity of TiO(2) for the photooxidation of organic substrates in water. The model was used to explain the trends in the experimental data for four different sets of photoactivity experiments with TiO(2) powders. The results of this study elucidate a strong effect of particle size on photoactivity. The effects of particle size on the efficiency of light absorption and scattering and charge-carrier dynamics at particle sizes less than 25 nm dominate the apparent photoactivity of TiO(2), and an optimum particle size of 25 to 40 nm exists within all sets of photocatalysis experiments conducted with TiO(2) powders in this study. The optimum particle size is a result of competing effects of effective particle size on light absorption and scattering efficiency, charge-carrier dynamics, and surface area. (C) 2002 Elsevier Science (USA).