title: Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures.
abstract: Here we report direct physical evidence that confinement of molecular hydrogen (H2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H2 at temperatures up to 67 K above the liquid-vapor critical temperature of bulk H2. This extreme densification is attributed to confinement of H2 molecules in the optimally sized micropores, and occurs at pressures as low as 0.02 MPa. The quantities of contained, solid-like H2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorption isotherms. The demonstration of the existence of solid-like H2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H2 density. Thus, this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.
authors.affiliation: Department of Chemical Engineering, University of Bath , Bath BA2 7AY, United Kingdom.
authors.forename: Valeska P
authors.initials: VP
authors.lastname: Ting
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831-6475, United States.
authors.forename: Anibal J
authors.initials: AJ
authors.lastname: Ramirez-Cuesta
authors.affiliation: Department of Chemical Engineering, University of Bath , Bath BA2 7AY, United Kingdom.
authors.forename: Nuno
authors.initials: N
authors.lastname: Bimbo
authors.affiliation: Department of Chemical Engineering, University of Bath , Bath BA2 7AY, United Kingdom.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Sharpe
authors.affiliation: Department of Chemical Engineering, University of Bath , Bath BA2 7AY, United Kingdom.
authors.forename: Antonio
authors.initials: A
authors.lastname: Noguera-Diaz
authors.affiliation: INM - Leibniz Institute for New Materials , Campus D2 2, 66123 Saarbrücken, Germany.|Department of Materials Science and Engineering, Saarland University , Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Presser
authors.affiliation: ISIS Facility, STFC, Rutherford Appleton Laboratory , Didcot OX11 0QX, United Kingdom.
authors.forename: Svemir
authors.initials: S
authors.lastname: Rudic
authors.affiliation: Department of Chemical Engineering, University of Bath , Bath BA2 7AY, United Kingdom.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mays
keywords: carbon; hydrogen storage; nanoporous materials; neutron scattering