The pH-dependant attachment of ceria nanoparticles to silica using surface analytical techniques
The pH-dependant attachment of ceria nanoparticles to silica using surface analytical techniques
复制标题
DOI：
10.1016/j.apsusc.2015.03.170
复制
发表时间：
2015-08-01
影响因子：
6.7
通讯作者：
Cadien, K.
中科院分区：
文献类型：
--
作者：
Dawkins, K.;Rudyk, B. W.;Cadien, K.
利用x射线光电子能谱（XPS）、扫描电子显微镜（SEM）和俄歇电子能谱（AES）测量研究了二氧化硅表面氧化铈颗粒的粘附和去除。提出了一种基于不同pH值下氧化铈浆液和二氧化硅颗粒的电泳迁移率测量的模型。XPS结果表明，在酸性pH值下，二氧化硅表面存在二氧化铈，但在碱性pH值下，二氧化铈的存在要少得多，或者在极端情况下不存在二氧化铈。SEM结果证实了XPS结果，在pH值为6时，二氧化硅表面的氧化铈颗粒分布均匀，而在pH值为12时，二氧化硅表面清洁。然而，扫描电镜图像显示，在类似于pH 9.6的情况下，在铈的等电点出现了氧化铈颗粒的团聚。高分辨率Ce 3d XPS分析表明，表面存在的铈的组成类似于31%的Ce（III）和69%的Ce（IV）。在二氧化硅表面的特定点进行的AES映射验证了XPS和SEM的结果。基于XPS， SEM和AES分析，很明显，碱性pH值是必要的，以尽量减少二氧化硅表面被二氧化铈颗粒污染。(C) 2015 Elsevier B.V.版权所有
The adhesion and removal of ceria particles to a silica surface was investigated with the use of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and auger electron spectroscopy (AES) measurements. A model is presented based on electrophoretic mobility measurements of ceria slurry and silica particles at different pH's. XPS results show that at acidic pH values, ceria is present on silica surfaces, but at alkaline pH values, far less ceria is present, or no ceria is present in the extreme case. SEM results corroborated the XPS results showing uniform distribution of ceria particles on silica surface at pH 6 while a clean silica surface is observed at pH 12. However, SEM images show agglomeration of ceria particles occurring at the isoelectric point of ceria at similar to pH 9.6. High resolution Ce 3d XPS analysis indicates that ceria present on the surface is composed similar to 31% Ce(III) and similar to 69% Ce(IV). AES mapping done at specific points on the silica surface validated both XPS and SEM results. Based on XPS, SEM and AES analyses, it is clear that an alkaline pH is necessary to minimize particulate contamination of silica surface by ceria. (C) 2015 Elsevier B.V. All rights reserved.