Extended friction elucidates the breakdown of fast water transport in graphene oxide membranes

¹ Department of Engineering, University of Rome “Roma Tre” - Via della Vasca Navale 79, 00141 Rome, Italy
² John A. Paulson School of Engineering and Applied Sciences, Harvard University - Cambridge, MA 02138, USA
³ Department of Enterprise Engineering “Mario Lucertini”, University of Rome “Tor Vergata” Via del Politecnico 1, 00133 Rome, Italy
⁴ Istituto per le Applicazioni del Calcolo, CNR - Via dei Taurini 19, 00185 Rome, Italy
⁵ Institute of Computational Physics, University of Vienna - Sensengasse 8/9, 1090 Vienna, Austria

Received: 10 November 2016
Accepted: 10 January 2017

Abstract

The understanding of water transport in graphene oxide (GO) membranes stands out as a major theoretical problem in graphene research. Notwithstanding the intense efforts devoted to the subject in the recent years, a consolidated picture of water transport in GO membranes is yet to emerge. By performing mesoscale simulations of water transport in ultrathin GO membranes, we show that even small amounts of oxygen functionalities can lead to a dramatic drop of the GO permeability, in line with experimental findings. The coexistence of bulk viscous dissipation and spatially extended molecular friction results in a major decrease of both slip and bulk flow, thereby suppressing the fast water transport regime observed in pristine graphene nanochannels. Inspection of the flow structure reveals an inverted curvature in the near-wall region, which connects smoothly with a parabolic profile in the bulk region. Such inverted curvature is a distinctive signature of the coexistence between single-particle zero-temperature (noiseless) Langevin friction and collective hydrodynamics. The present mesoscopic model with spatially extended friction may offer a computationally efficient tool for future simulations of water transport in nanomaterials.