▎ 摘　　要

In this work, we have developed multilayer nanoporous graphene oxide-based membranes by (1) taking advantage of nematic liquid crystalline phase of graphene oxide (GO) and alignment of pores through shear forces (SA GO) and (2) holey graphene (hG) with extremely controlled narrow pore size distribution via catalytic metal oxidation, for the efficient transport of water and rejection of undesired solute ions, as potential successor of reverse osmosis nanofiltration membranes. The membranes performance was evaluated by measuring flux (permeability) and rejection (retention and adsorption) with applied pressure using a dead-end filtration cell investigating steady-state permeation properties. These ordered, continuous SA GO and hG membranes (similar to 140 +/- 20 nm thick) demonstrated faster water transport (higher permeability; similar to 70 +/- 12 L m(-2) h(-1) bar(-1)), higher retention for charged and uncharged organic probe molecules (>95%) with hydrated radii >5 A and modest (similar to 40%) to high (similar to 70%) rejection of mono- and divalent ion salts. The superior flux and efficient transports are attributed to the formation of in-plane organized, molecule-hugging cylindrical (slit-like) and spherical (pore-like) nanochannels with optimum interlayer distance, low friction and large slip length of water following pore-flow model. The ion rejection mechanism from these primarily negatively charged membranes reveal that physical sieving and electrostatic interactions dominate the filtration process. We also presented the results with extremely cost-effective use of xylem plant as a natural filtration medium for economical disadvantaged regions and countries where potable freshwater is limited or lacking. These findings demonstrate a facile scalable method to obtain G-based membranes with reasonable good stability, adjustable thickness and tunable interlayer spacing, thereby eliminating problems typically caused by aggregation limiting practical use of functional moieties.