Beyond the single-layer limit for desalination based on conical channels of multilayer nanoporous graphene membranes

Abstract

Nanoporous graphene monolayer has been proved to be a candidate for desalination with high permeability due to its ultrathin nature, however, it is still challenging to produce at large scales, which hampers its practical applications. Here, we propose a multilayer membrane strategy for high-efficiency desalination beyond the single-layer limit using conical channels formed by graphene multilayer of nanopores. By varying the number of layers and the cone angle, molecular dynamics simulations demonstrate that the water flux for the channels made of four-layer graphene at the cone angles of 8.6°, 19.1° and 35° is much larger than that the monolayer graphene with the pore size identical to that of the smallest pore of multilayer. Based on the channel with cone angle of 19.1°, we further find that N-functionalized conical channels exhibit promising desalination performance in terms of both water permeability and salt rejection. This work provides a useful guideline for the application of multilayer graphene membranes in the field of desalination.