(444a) QSDFT Method for Characterization of Mesoporous Carbons

The density functional theory (DFT) is a well-established tool for modeling adsorption in meso- and micropores, which was employed for developing a series of computational methods for determining the pore size distribution (PSD) from adsorption isotherms [1,2]. The non-local density functional theory (NLDFT) methods have been implemented in the data reduction software of commercial instruments are currently widely used for structure characterization of various mesoporous and microporous materials based on adsorption of nitrogen, argon, and carbon dioxide. However, the emergence of novel materials with pre-designed pore morphology requires the development of new methods, which take into account the specifics of these new structures. Recently, the NLDFT method was advanced to take into account the surface roughness that is inherent to most of carbonaceous, silica, and other materials, including hybrid organic-inorganic hierarchical structures [3,4]. This new technique, named the quenched solid density functional theory (QSDFT), was shown to be quite important for analyses of microporous carbons, since the QSDFT method eliminates artificial peaks on calculated PSDs, which evolve due the assumption of the ideally smooth surface in the NLDFT method.

The current work extends the QSDFT method to the novel materials – mesoporous carbons with the cage-like and channel-like pore geometries. To this end, we have built a set of hybrid QSDFT kernels comprising of the theoretical isotherms of nitrogen and argon adsorption in the spherical and cylindrical pores ranging from 0.5 to 50 nm embracing the whole range of micro- and mesopores. The application and validation of these novel kernels will be demonstrated by using novel micro/mesoporous carbons consisting of either cylindrical and spherical mesopores (e.g. CMK-type carbons, and other carbons materials obtained via hard and soft templating routes), and by comparison with independent methods (e.g. X-ray scattering).

[1] Lastoskie C., Gubbins K.E., Quirke N. J. Phys. Chem. 97 4786-4796 (1993).

[2] Ravikovitch P.I., O’Domhnaill S.C., Neimark A.V., Schuth F., Unger K.K.,  Langmuir,  11, 4765-4772 (1995).

[3] Ravikovitch P.I., Neimark A.V., Langmuir 22, 11171-11179 (2006).

[4] Neimark A.V., Lin Y., Ravikovitch P.I., Thommes M., Carbon, 47, 1617-1628 (2009).