透射电镜三维重构确定中孔炭六角孔道结构

Transmission electron microscope identification of a hexagonal porous arrangement in ordered mesoporous carbon

有序中孔炭(OMCs)的孔道结构对于材料的性能有着重要影响,但利用X射线衍射和单一位向的透射电镜形貌不能快捷地分析其孔道结构。利用透射电镜三维重构法发展了一种直观而又严谨的快速确定六角孔道中孔炭的方法。即,在透射电镜中围绕样品相互垂直的两个轴向分别倾转一定角度,得出孔道结构的特征形貌像,分析不同位向下孔径参数之间的几何关系,进而确定中孔炭孔道结构的合理模型。利用该法对有机模板法制备的树脂基OMCs进行表征,得出OMCs孔径比较均匀,呈六方排列,孔道间距约11 nm。由此表明,利用透射电子显微镜沿着直线型孔道延伸方向和垂直于延伸方向进行系列倾转即可快速确定OMCs是否为六角结构,并快捷测出孔道排列的尺寸参数。

The overall properties of ordered mesoporous carbons （OMCs） are essentially influenced by the pore structure. However, neither X-ray diffraction analysis nor transmission electron microscopy （TEM） micro- graphs can identify the pore structure correctly. Therefore, a three-dimensional （3D） reconstruction method from TEM was carefully developed to investigate the structure and parameters of OMCs. Characteristic pore images of OMCs can be obtained by separately tilting along the two vertical axes using a 3D specimen holder. Pore parame- ters and a model of their arrangement can be readily obtained by analyzing the geometrical relationship of pore images of OMCs with different azimuths. As an example, OMCs synthesized from resin using an organic tem- plate method were investigated. It is concluded that the OMCs have an ordered hexagonal arrangement with a uniform pore size of 11 nm. It is demonstrated that a series of tiltings about two vertical axes can easily confirm whether the arrangement of OMCs is hexagonal or not. The structure model and parameters of OMCs with hexa- gonal symmetry can also be easily identified by this method.