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

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) micrographs 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 parameters 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 template 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 hexagonal symmetry can also be easily identified by this method.