Wilson Gregory J, Matijasevich Aaron S, Mitchell David R G, Schulz Jamie C, Will Geoffrey D
Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane Queensland, Australia.
Langmuir. 2006 Feb 28;22(5):2016-27. doi: 10.1021/la052716j.
The effect of microwave modification of colloidal TiO2 suspensions under extended periods of treatment is presented. The nanoparticulate TiO2 is compared and contrasted to similar convection hydrothermally treated TiO2 and a commercial titania product, namely Degussa P25. Microwave-treated samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy to determine their physicochemical characteristics. Comparative surface area analyses were performed by N2 adsorption and calculated from a Brunauer-Emmett-Teller (BET) isotherm. The complementary techniques of XRD and TEM showed good correlation between observed and calculated particle sizes (by application of the Scherrer equation), with the material being highly crystalline anatase TiO2, as identified by XRD and Raman. This investigation identified that extended periods of microwave hydrothermal treatment do not greatly enhance the crystallinity and primary grain size. Treatment of >180 min has a negative effect on crystallite growth; however, treatment up to this time had a significant effect on the material's surface area. The limiting regime of Ostwald ripening for hydrothermal treatment is discussed in relation to the mechanism of microwave treatment, that is, rapid heating to temperature and extremely rapid rates of crystallization. The effect of these property modifications are further discussed in relation to photocatalytic and photoelectrochemical applications of TiO2 nanoparticles.
本文介绍了在长时间处理条件下微波改性胶体TiO₂悬浮液的效果。将纳米TiO₂颗粒与类似的对流水热处理TiO₂以及一种商业二氧化钛产品（即德固赛P25）进行了比较和对比。通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和拉曼光谱对微波处理后的样品进行分析，以确定其物理化学特性。通过N₂吸附进行比较表面积分析，并根据布鲁诺尔-埃米特-泰勒（BET）等温线进行计算。XRD和TEM的互补技术显示，观察到的粒径与计算出的粒径（通过应用谢乐方程）之间具有良好的相关性，通过XRD和拉曼光谱鉴定，该材料为高度结晶的锐钛矿TiO₂。本研究确定，长时间的微波水热处理不会显著提高结晶度和一次晶粒尺寸。处理时间超过180分钟对微晶生长有负面影响；然而，在此之前的处理对材料的表面积有显著影响。结合微波处理的机制，即快速加热到温度和极快的结晶速率，讨论了水热处理的奥斯特瓦尔德熟化的极限状态。进一步讨论了这些性质改性对TiO₂纳米颗粒光催化和光电化学应用的影响。
