Consecutive Water Transport through Zero-Dimensional Graphene Gates of Single-Walled Carbon Nanohorns

The unique water transport properties in nanospaces are essential for control of various chemical reactions, biochemical activities, and electrochemical systems. Fast water transport has been observed in one-dimensional nanospaces. However, water transport via zero-dimensional nanospaces has not yet been observed. Zero-dimensional nanospaces were obtained by extremely small and thin gate (zero-dimensional gate) insertion on graphene walls of single walled carbon nanohorns. The water transport properties were examined by water vapor loading and release via the zero dimensional gates, and molecular dynamics simulation. Although relatively large gates provided considerable adsorption hysteresis by long-term equilibrium, water vapor loading and release via the extremely small gates showed consecutive water loading and release. The molecular dynamics simulation showed consecutive water transport via the gates, probably because of lower energy barriers to water transport in the vicinity of the gates. The zero-dimensional gates rejected water vapor transfer, but admitted condensed water for transfer.