表面活性剂对TiO2纳米晶体生长动力学的影响∗

摘要

采用水热法,分别以丙二酸、正丁醇、乙二胺为表面活性剂,研究3种体系下 TiO2纳米晶体的生长过程.XRD结果显示3种体系下主要产物为锐钛矿TiO2；TEM和 HRTEM结果表明在不同的生长阶段,纳米晶体的生长结构特点明显不同.分别采用定向生长理论(Orientation attachment,OA)、弗兰克尔收缩理论(Frenkel shrinking,SH)、奥斯特瓦尔德熟化理论(Ostwald ripening,OR)对3种体系下的晶体生长进行理论模拟,结果发现在丙二酸、乙二胺体系下晶体生长分为3个阶段：定向聚集生长、颗粒收缩、奥斯特瓦尔德熟化,且乙二胺体系下颗粒明显增大；但是在正丁醇体系下晶体生长仅显示明显的 OR 特征,不存在OA生长.理论和实验分析说明不同体系下晶体生长方式不同的主要原因是由于3种表面活性剂以及溶液pH 值的不同作用.%It is investigated that the growth process of TiO2 nanocrystalline under the hydrothermal condition with the presence of malonic acid,butyl alcohol or ethylenediamine.The XRD results show that the products are anatase and the images of TEM and HRTEM show that the construction feather of TiO2 nanoparticles is dif-ferent at the different stage.Furthermore,three nanoparticle growth models,such as Orientation attachment (OA),Frenkel shrinking (SH)and Ostwald ripening (OR),were employed to fit nanoparticle growth data in order to elucidate growth mechanisms operating during hydrothermal aging.It is discovered that a unique three-stage hydrothermal growth of anatase nanoparticles is presented in malonic acid and ethylenediamine:OA,SH, and OR.The crystalline size under ethylenediamine is bigger than that under malonic acid.The Ostwald ripe-ning mechanism is dominant under butyl alcohol.According to the data,the different growths depend on the de-tailed interplay between bulk solution pH and surface chemistry.