Optimizing the photocatalytic properties of hydrothermal TiO2 by the control of phase composition and particle morphology.: A systematic approach
Optimizing the photocatalytic properties of hydrothermal TiO2 by the control of phase composition and particle morphology.: A systematic approach
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DOI：
10.1021/ja067050
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发表时间：
2007-03-28
影响因子：
15
通讯作者：
Morazzoni, Franca
中科院分区：
文献类型：
--
作者：
Testino, Andrea;Bellobono, Ignazio Renato;Morazzoni, Franca
通过调整其晶体结构和形态来控制TiO 2纳米粒子的光催化活性的可能性是当前非常感兴趣的话题。在这项研究中，各种各样的多面颗粒具有不同的相组成，尺寸和形状已获得从浓缩的TiOCl 2溶液通过系统地改变温度，pH值，和水热处理的持续时间。根据已有的热化学数据建立了热力学模型，为选择合适的实验条件提供了指导。通过结合TEM、HRTEM、XRD、密度和比表面积测量的结果，对颗粒进行了完整的结构和形态表征。在苯酚溶液的紫外光降解的光催化活性和粒径之间的相关性建立。长/宽比约为5、宽度为60-100 nm的棱形金红石颗粒活性最高。还研究了颗粒的表面化学。降低表面酸性的处理，例如用氨溶液洗涤粉末和/或在400 ℃下煅烧，对光催化活性具有不利影响。总体结果表明，粒子形态和光催化活性之间的相关性，并表明，电子-空穴复合和吸附在表面可以速率控制过程。在这项研究中提出的系统的方法表明，一个实质性的改善，可以实现通过精心设计的颗粒形态和控制的表面化学的二氧化钛的光催化活性。
The possibility of controlling the photocatalytic activity of TiO2 nanoparticles by tailoring their crystalline structure and morphology is a current topic of great interest. In this study, a broad variety of well-faceted particles with different phase compositions, sizes, and shapes have been obtained from concentrated TiOCl2 solutions by systematically changing temperature, pH, and duration of the hydrothermal treatment. The guide to select the suitable experimental conditions was provided by thermodynamic modeling based on available thermochemical data. By combining the results of TEM, HRTEM, XRD, density, and specific surface area measurements, a complete structural and morphological characterization of the particles was performed. Correlation between the photocatalytic activity in the UV photodegradation of phenol solutions and the particle size was established. Prismatic rutile particles with length/width ratio around 5 and breadth of 60-100 nm showed the highest activity. The surface chemistry of the particles was also investigated. Treatments that decrease the surface acidity, such as washing the powders with ammonia solution and/or calcining at 400 degrees C, have detrimental effect on photocatalytic activity. The overall results suggest correlation between particle morphology and photocatalytic activity and indicate that both electron-hole recombination and adsorption at the surface can be rate-controlling processes. The systematic approach presented in this study demonstrates that a substantial improvement of the photocatalytic activity of TiO2 can be achieved by a careful design of the particle morphology and the control of the surface chemistry.