title: Water in Carbon Nanotubes: The Peculiar Hydrogen Bond Network Revealed by Infrared Spectroscopy.
abstract: A groundbreaking discovery in nanofluidics was the observation of the tremendously enhanced water permeability of carbon nanotubes, those iconic objects of nanosciences. The origin of this phenomenon is still a subject of controversy. One of the proposed explanations involves dramatic modifications of the H-bond network of nanoconfined water with respect to that of bulk water. Infrared spectroscopy is an ideal technique to follow modifications of this network through the inter- and intramolecular bonds of water molecules. Here we report the first infrared study of water uptake at controlled vapor pressure in single walled carbon nanotubes with diameters ranging from 0.7 to 2.1 nm. It reveals a predominant contribution of loose H bonds even for fully hydrated states, irrespective of the nanotube size. Our results show that, while the dominating loosely bond signature is attributed to a one-dimensional chain structure for small diameter nanotubes, this feature also results from a water layer with "free" OH (dangling) bonds facing the nanotube wall for larger diameter nanotubes. These experimental findings provide a solid reference for further modeling of water behavior in hydrophobic nanochannels.
authors.affiliation: Synchrotron SOLEIL, AILES beamline, L'Orme des Merisiers , Saint Aubin, BP 48, 91192 Gif sur Yvette Cedex, France.
authors.forename: Simona
authors.initials: S
authors.lastname: Dalla Bernardina
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Erwan
authors.initials: E
authors.lastname: Paineau
authors.affiliation: Synchrotron SOLEIL, AILES beamline, L'Orme des Merisiers , Saint Aubin, BP 48, 91192 Gif sur Yvette Cedex, France.
authors.forename: Jean-Blaise
authors.initials: JB
authors.lastname: Brubach
authors.affiliation: Laboratoire Léon Brillouin, CNRS-CEA-UMR 12, CEA-Saclay, Université Paris-Saclay , 91191 Gif sur Yvette Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Judeinstein
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Stéphan
authors.initials: S
authors.lastname: Rouzière
authors.affiliation: Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Launois
authors.affiliation: Synchrotron SOLEIL, AILES beamline, L'Orme des Merisiers , Saint Aubin, BP 48, 91192 Gif sur Yvette Cedex, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Roy