Molecular dynamics of electric field enhanced water permeation through N-doped graphene.

contextNanoporous graphene has emerged as a promising platform for desalination because its atomic thickness and tunable pore chemistry can, in principle, overcome the conventional permeability-selectivity trade-off of polymeric reverse osmosis membranes. Here, we investigate water and ion transport through a single-layer pyridinic-N-doped nanoporous graphene membrane containing sub-nanometer pores with an effective diameter of ~ 2.75 Å, separating a saline feed from a pure permeate reservoir under an axial electric field of 0.05 V Å⁻

methodsWe performed non‑equilibrium classical molecular dynamics simulations of a slit‑pore desalination cell containing a pyridinic‑N‑doped nanoporous graphene membrane, explicit water, and NaCl electrolyte. Water was represented by a rigid four‑site TIP4P‑family model, and Na⁺/Cl⁻ parameters were chosen to be compatible with this water model. The N‑doped graphene sheet, patterned with ~ 2.75 Å pores and decorated at the rims by pyridinic-N, was modeled using an AIREBO/REBO‑type potential for C-C and C-N bonding. Electrostatics were treated with a particle-particle particle-mesh (PPPM) method under three‑dimensional periodic boundary conditions and van der Waals interactions were described by Lennard-Jones potentials with Lorentz-Berthelot mixing and an appropriate real‑space cutoff. A uniform external electric field of 0.05 V Å⁻