Characterization of a New Solid Having Graphitic Hexagonal Pores with a GCMC Technique

Abstract

Recently, Morishige (Morishige, K.Freezing and melting of Kr in hexagonally shaped pores of turbostratic carbon: Lack of hysteresis between freezing and melting. J. Phys. Chem. C 2011, 115 (6), 2720−2726) synthesized a new and exciting porous carbon material that has regular and nonconnected hexagonal pores with graphitic walls. Classical theories, such as the BJH or the DFT method, are unsuitable to characterize this material because the kernel (family of local isotherms) is based on model cylindrical pores. We present in this paper a new characterization based on a GCMC simulation of hexagonal pores that can account for the pore size, the surface morphology, and the heterogeneity arising from either structural or energetic defects. The molecular model describes the adsorption isotherms and the isosteric heat at 77.4 and 87.3 K over a wide range of pressures. This new material and the successful molecular model provide us with an ideal system to study adsorption mechanisms in a confined space, including the effects of confinement on the 2D transition for temperatures below the triple point and the 3D-capillary condensation for temperatures below the critical point of the bulk fluid.