Water transport through a multilayer graphene pore in electric fields: Effect of pore size arrangement

Abstract

In recent experiments, multilayer graphene sheets can be fabricated through van der Waals assembly, where the pore size could have different distributions and arrangements; however, our understanding on how this affects water transport is still rather poor. In this work, we use molecular dynamics (MD) simulations to study the transport of water through a multilayer graphene pore in electric fields, focusing on the effect of pore size arrangement. We consider the arrangement of two pore sizes, namely S1212 (uniform) and S1122 (concentrated), respectively. Notably, because of different friction environment, the water dynamics exhibit a bifurcation for S1212 and S1122. For example, with the increase in electric field, the water flux and flow both exhibit a monotonous decrease for S1212; while for S1122 the water flux increases monotonously and the water flow displays a minimum behavior. For the change of electric fields and pore length (graphene layer number), S1122 always has a larger water flux, water flow and unidirectional transport efficiency, as well as a smaller translocation time. Consequently, we can conclude that a more concentrated pore size arrangement facilitates the water transport, providing a new direction for the design of high flux nanofluidic devices.