The energetics and diffusion of water molecules and hydrated ions (Na+, Cl-) passing through nanopores in graphene are addressed by dispersion-corrected density functional theory calculations and ab initio molecular dynamics (MD) simulations. Pores of about 0.8 nm in diameter with different pore-edge passivations, with (H) and (O, H) atoms, were considered. Our MD simulations show a water flux through the hydroxylated pores of about one H2O molecule every three picoseconds, in close agreement with recent experiments that estimated a water flux of three molecules per picosecond through pores of ∼1 nm. We also find that both pores are effective in blocking hydrated Na+ and Cl- ions with large energy barriers, ranging from 12 to 15 eV. In addition, pore passivation with O atoms would increase the water transport through hydroxylated pores, due to the formation of hydrogen bonds with nearby water molecules, which is not observed in the hydrogenated pores.
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry