Tuning intrinsic water permeation barriers in nanoporous graphene via systematic pore-edge modification: a...

Nanoporous graphene (NPG), with its atomically thin structure and chemically tunable pore rims, offers a promising pathway toward high-flux water membranes. However, realistic graphene pores are chemically functionalized during fabrication, and the resulting edge chemistry strongly influences water transport. In this study, we use density functional theory and climbing-image nudged elastic band calculations to investigate intrinsic single-molecule water permeation barriers through a 10-vacancy graphene pore with hydrogen, fluorine, hydroxyl, nitrogen, and mixed H-F, H-OH, H-N, and F-N edge terminations. For each composition, multiple symmetry-distinct configurations are analyzed, and thermally significant ones are identified using formation energies and canonical probabilities at 300 K. The results show that fully hydroxylated and fully fluorinated rims are kinetically unfavorable, whereas nitrogen-rich and selected mixed terminations reduce the intrinsic barrier. In particular, mixed H-OH, H-F, and H-N rims provide low-barrier pathways, with some configurations approaching effectively barrierless single-water permeation. Two-water calculations for representative low-barrier pores show sequential single-water permeation without cooperative blocking, while vibrational corrections do not change the configurational stability ordering. Configuration-induced uncertainty analysis shows barrier spreads of ≈ 0.03-0.68 eV depending on edge arrangement. These findings demonstrate the strong sensitivity of water permeation to pore-rim chemistry and configuration, offering atomistic guidance for designing NPG water membranes with minimal energetic resistance.