Direct evidence of the ultramicroporous structure of carbon molecular sieves
Young Hee Yoon, Daniel O’Nolan, Michelle L. Beauvais, Karena W. Chapman, Ryan P. Lively
Abstract
We utilize gas sorption experiments, neutron pair distribution function, and small-angle X-ray scattering studies on carbon molecular sieves (CMSs) to gain new insight into their ultramicroporous structure. CMS materials derived from the pyrolysis of PIM-1 (PIM = polymer of intrinsic microporosity) under an inert atmosphere (PIM-1-CMS) and H2 atmosphere (4% H2-PIM-1-CMS) were studied. Neutron total scattering studies of these materials reveal these CMS materials to be mainly graphene-like ribbons with short-range atomic ordering. Small-angle X-ray scattering and low angle diffraction peaks corroborate the presence of well-defined ultramicroporosity observed in carbon dioxide and cryogenic neon adsorption studies suggesting, expectedly, that these materials are non-graphitizing carbon structures. Our findings provide microscopic evidence of the non-graphitizing and ribbon-like structure of these CMS materials and suggest a possible hypothetical microporous structure.