3D nanostructure prediction of porous carbons via gas adsorption

Abstract

Structural characterization of porous carbon materials is critical for the evaluation of their synthesis procedures and performance. Throughout the last decades, many methods have been employed to determine porosity properties from gas adsorption such as surface area, pore size distribution (PSD) and real density. However, gas adsorption models use 1D structures of carbon nanopores, although adsorption and separation properties of nanoporous carbons are governed by 3D pore parameters. Estimating the 3D nanostructure of nanoporous carbons using gas adsorption would accelerate progress in research and implementation of nanoporous carbons. We report here a promising 3D pore nanostructural characterization from gas adsorption. Using atomistic simulations, we have generated a database of realistic 3D porous carbon structures spanning a wide range of pore sizes and geometries. After calculating their gas adsorption isotherms, we employed a numerical procedure to find the relative contribution for each of the structures to the adsorption isotherm of a nanoporous carbon sample. These contributions allowed us to estimate the surface area and pore size distribution of carbon materials; moreover (and perhaps more importantly!), we will show that the plausible 3D pore structures correlate very well with the local carbon structure as experimentally determined by high-resolution TEM observations and can successfully predict adsorption of different molecules. This is a powerful procedure that can be extended to other materials, and with enough computer power, to larger pore sizes.