Performance comparison of slit and nanoporous graphene oxide membranes in water desalination

Graphene oxide (GO) membranes have emerged as promising candidates for water desalination as a result of their structural and transport properties. In this study, we employ fully atomistic classical molecular dynamics simulations to investigate the performance of monolayer GO membranes featuring pore- and slit-like nanostructures. We analyze the influence of the width of the slits, ranging from 0.8 to 1.5 nm, on water transport and salt rejection by monitoring the spatial and temporal distributions of water molecules and ions. Furthermore, we assess the effect of applied pressure on water density profiles and compute the potential of mean force for water molecules traversing the slits. Our results reveal that slits offer tunable transport characteristics and that nanopores generally outperform slits in the combined metrics of water flux and ion exclusion at low pressures. At higher pressures, however, 1.0-1.5 nm slits exhibit a permeability gain that can exceed comparable nanopore systems, with a reduction in salt rejection, whereas 0.8 nm slits retain near-complete ion exclusion over the range examined. These findings delineate operating regimes in which each architecture is advantageous and guide the optimization of nanostructure design for advanced desalination technologies.