| 초록 |
The Surface area is one of the most important physical properties of porous material. Generally, surface areas are determined from a N2 adsorption isotherm using the Brunauer–Emmett–Teller (BET) method. However, a recent IUPAC report recommends using an Ar adsorption isotherm instead of the N2 adsorption isotherm to compute the BET surface area due to the purported “orientational” effect. However, the magnitude of such effect has not been fully characterized in the literature, making it difficult for the community to accept the new standard for porous materials characterization. In this study, we carried out large-scale molecular simulations to investigate the orientational effect of N2 and its impact on accurately determining the surface area. The change of the van der Waals interaction between the graphene sheet and gas molecules resulted in a change in the orientation distribution of N2 on the monolayer. However, when we compared the differences between the true monolayer area and geometric area of N2 and Ar, There was no significant difference. Finally, we comment on the effect of surface curvature on the orientation of N2 molecules. |
