  Porous graphene has high mechanical strength and atomic layer thickness,
which make it a promising material for material separation and biomolecule
sensing. Electrostatic interactions between charges in aqueous solution are a
kind of strong long-range interaction which may have great influence on the
fluid transport through nanopores. Here, molecular dynamics simulations were
conducted to investigate ion and water transport through a 1.05-nm-in-diameter
monolayer graphene nanopore with its edge charge-modified. From the results, it
is found that the nanopores are selective to counterions when they are charged.
As the charge amount increases, the total ionic currents show an
increase-decrease profile while the co-ion currents monotonously decrease. The
co-ions rejection can reach 75% and 90% when the nanopores are negatively and
positively charged, respectively. Cl ions current increases and reaches a
plateau, and Na+ current decreases with the charge amount in the systems where
they act as counterions. Besides, the charge modification can enhance the water
transport through nanopores obviously. This is mainly due to the ion selection
of nanopores. Especially, positive charges on the pore edge facilitate the
water transport much more than negative charges.

Chemical Physics;Soft Condensed Matter