A new approach to characterize the nanostructure of activated carbons from mathematical morphology applied to high resolution transmission electron microscopy images

Abstract : A new characterization method of the nanoporous structure of activated carbons (ACs) is proposed, based on mathematical morphology analysis of high resolution transmission electron microscopy (TEM) images. It produces refined statistics describing the shape, size and orientation of the defective graphene sheets seen edge on as individual fringes on TEM images. It also provides some quantitative information regarding their spatial arrangement. Especially, assemblages composed of 2-4 nearly parallel fringe fragments could be detected, which were relevant of some partial stacking of the defective graphene sheets. Such assemblages were possibly locally oriented along a common direction to form large continuous domains. To prove the ability of the image analysis tool to reveal distinctive features and degrees of disorder of the AC structures, a set of various commercial carbon adsorbents was characterized. The measured effective spaces separating the individual fringes, the stacks and the continuous domains were examined and compared with the porosity data derived from 77 K-N2 adsorption isotherms. Consistency between the two sets of data was assessed and interpreted by considering the N2 diffusional limitations resulting from the micropore network connectivity.