Molecular mechanism of water permeation in helium impermeable graphene and graphene oxide membrane

Abstract

The layers of graphene oxide (GO) are found to be good for permeation of water but not for helium (Science 2012 335 (6067): 442-444) suggesting that the GO layers are dynamic in the formation of permeation route depending on the environment they are in (i.e, water or helium). To probe the microscopic origin of this observation we calculate the potential of mean force (PMF) of GO sheets (oxidized and reduced parts), with inter-planar distance as reaction coordinate in helium and water. Our PMF calculation shows that equilibrium interlayer distance between oxidized part of GO sheets in helium is at 4.8 Å leaving no space for helium permeation. In contrast PMF of oxidized part of GO in water shows two minima one at 4.8 Å and another at 6.8 Å corresponding to no water and water filled region and thus giving rise to permeation path. The increased electrostatic interaction between water with the oxidized part of the sheet helps the sheet opening up and pushing water inside. Based on the entropy calculations for water trapped between graphene sheets and oxidized graphene sheets at different inter-sheet spacing we also show the thermodynamics of filling.

References in corpus (6)

• Unimpeded permeation of water through helium-leak-tight graphene-based membranes
• Precise and ultrafast molecular sieving through graphene oxide membranes
• Breakdown of Fast Water Transport in Graphene Oxides
• Strong Correlations and Fickian Water Diffusion in Narrow Carbon Nanotubes
• Thermodynamics of Water Entry in Hydrophobic Channels of Carbon Nanotubes
• Driving force of water entry into hydrophobic channels of carbon nanotubes: entropy or energy?

Cited by in corpus (2)

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• Influence of Surface Hydrophilicity and Hydration on the Rotational Relaxation of Supercooled Water on Graphene Oxide Surfaces