Dynamics of water confined in a graphene nanochannel: dependence of friction on graphene chirality

Numerous recent studies reveal that water transport through graphene-based nanochannels exhibits unconventional behavior. Theoretical and experimental works have reported that the dynamic behavior of the constrained water could be affected by the atomic structure, surface curvature, confinement height, pressure, and mechanical strain of the confining channel. However, few studies concern the role of graphene chirality in the dynamics of confined water. In the present study, using equilibrium molecular dynamics (EMD) simulations, we simulated the water flow through different graphene-based channels to investigate the influence of graphene chirality on the dynamic behavior of the confined water. The friction coefficient at the water/graphene interface was found to be dependent on the crystallographic orientation of the graphene wall. The results also indicated that the chirality-dependent friction behavior was affected by the confinement height of the channel. Detailed analyses on the physical origin of such a chirality effect suggested that the chirality-dependent friction was ascribed to the water-graphene interaction energy barrier variation when the water flow was driven along the armchair edge and zigzag edge. These findings are beneficial to the design of graphene-based nanofluidic devices.