It was shown that ordering in nanoscale water film on a hydrophobic surface gives rise to fast diffusion of water. Specifically, as the surface coverage of water increases, the diffusion coefficient of water increased until a critical surface coverage and a further increase in surface coverage results in a decrease of water diffusion coefficient. For thin nanoscale films that form two layers of waters on a hydrophobic surface, the first layer of water forms a hexagonal structure, very similar to the ice Ih structure, that was independent of the surface coverage. As the surface coverage increases, the ordering of water molecules in the second layer increased and for a critical surface coverage the ordering in the second layer was maximized and the hydrogen bonding between first and second layers was minimal giving rise to fast diffusion. As the surface coverage further increases, the hydrogen bonding between the first and second layers increased and the diffusion coefficient of water was reduced. This so-called ordering-induced diffusion enhancement on hydrophobic surfaces was contrary to the ordering-induced slow mobility in hydrophobic nanotubes (e.g., in a carbon nanotube).

Ordering-Induced Fast Diffusion of Nanoscale Water Film on Graphene. Park, J.H., Aluru, N.R.: Journal of Physical Chemistry C, 2010, 114[6], 2595-9