The interaction between atomic-scale pores and particles

Abstract

Using first-principles calculations for angstrom-sized pores (3–10 Å), we investigate pore-particle interaction. The translocation energy barrier (TEB) plays important role for the angstrom-scale pores created in 2D-materials such as graphene which is calculated for the translocation of rare gases (He, Ne, Ar, Xe), diatomic molecules (H₂ and N₂), CO₂, and CH₄. The critical incident angle (the premeance beyond that is zero) was found to be 40°, which is different from classical model’s prediction of 19–37°. The calculated TEB (Δ) and the surface diffusion energy barrier (Δ′) for the particles with small kinetic diameter (He, Ne and H₂), show that the direct flow is the dominant permeation mechanism (Δ ≈ 0 and Δ′ > 30 meV). For the other particles with larger kinetic diameters (Ar, Kr, N₂, CH₄ and CO₂), we found that both surface diffusion and direct flow mechanisms are possible, i.e. Δ and Δ′ ≠ 0. This work provides important insights into the gas permeation theory and into the design and development of gas separation and filtration devices.