Testing the feasibility of using the density functional theory route for pore size distribution calculations of ordered microporous carbons

Abstract

The pore size distribution (PSD) characterization of microporous carbon materials is traditionally obtained from the analysis of N2 adsorption isotherms at 77 K. In this work, we aim at testing the feasibility of using the density functional theory (DFT) route for PSD calculations of interconnected carbon pore structures. The first step of this study was to generate using an atomistic simulation approach, an ordered porous carbon material with well-defined porosity using NaY zeolite as a templating matrix. For this purpose, we used the grand canonical Monte-Carlo (GCMC) technique in which the carbon–carbon interactions were described within the frame of a newly developed tight binding approach and the carbon–zeolite interactions assumed to be characteristic of physisorption. We calculated the PSD of such a carbon porous material. At a second stage, we calculated nitrogen adsorption isotherms at different temperatures. These data were subsequently used as inputs for DFT calculation to obtain the PSD. Comparisons between DFT–PSD and MC–PSD are made. In particular, we show that with an appropriate wall thickness of two graphene layers, the PSD obtained from DFT calculation agrees well with that from direct analysis of the simulated structure.