Water Transport through Ultrathin Graphene

Abstract

Graphene can be considered as an ideal membrane since its thickness is only one carbon diameter. In this study, using molecular dynamics simulations, we investigate water transport through a porous graphene membrane and compare the results with water transport through thin (less than 10 nm in thickness/length) carbon nanotube (CNT) membranes. For smaller diameter pores, where a single-file water structure is obtained, CNT membranes provide higher water flux compared to graphene membranes. For larger diameter pores, where the water structure is not single-file, graphene membranes provide higher water flux compared to CNT membranes. Furthermore, in thin CNT membranes, the water flux did not vary significantly with the thickness of the membrane. We explain the results through a detailed analysis considering pressure distribution, velocity profiles, and potential of mean force. This work opens up opportunities for graphene-based membranes in molecular sieving, water filtration, fuel cells, and so forth.