Anomalous spontaneous capillary flow of water through graphene nanoslits: Channel width-dependent density
Journal
Journal of Molecular Liquids
Journal Volume
352
Date Issued
2022
Author(s)
Abstract
Unexpectedly fast flow (up to 1 m/s) of water in graphene nanoslits was reported in experiments, revealing the breakdown of Washburn's equation with no-slip condition. In this work, the imbibition dynamics of water into graphene nanoslits, ranging in width from one to ten atomic planes, is explored via Molecular Dynamics. The density of imbibed water in the nanoslit is analyzed and it depends on the channel width. Moreover, the interfacial tensions, equilibrium contact angle of water on the graphene sheet, and slip lengths of steady flow in nanoslits are evaluated. The slip length is found to decrease with increasing the channel width. The analyses of spontaneous capillary flow indicate that the time evolution of the penetration length follows Washburn's equation qualitatively and the flow rates are comparable to the experimental results. However, the dependence of the imbibition rate on the channel width does not agree with Washburn's equation at all. As the channel width-dependent slip length is introduced, the imbibition dynamics can be reasonably described by Washburn's equation. The channel width-dependent behavior can be explained by the variation of the water state with the channel width, which can be realized by the changes of water densities and hydrogen bonds with the channel width. ? 2022 Elsevier B.V.
Subjects
Anomalous spontaneous capillary flow
Channel width dependence
Graphene nanoslits
Penetration length
Washburn equation
Capillarity
Capillary flow
Channel flow
Contact angle
Hydrogen bonds
Molecular dynamics
Nanostructures
Atomic planes
Channel widths
Graphene nanoslit
Nanoslits
No-slip condition
Slip length
Graphene
SDGs
Type
journal article