Direct evidence for solid-like hydrogen in a nanoporous carbon hydrogen storage material at supercritical temperatures

Ting, Valeska P., Ramirez-Cuesta, Anibal J., Bimbo, Nuno, Sharpe, Jessica E., Noguera-Diaz, Antonio, Presser, Volker, Rudic, Svemir and Mays, Timothy J. (2015) Direct evidence for solid-like hydrogen in a nanoporous carbon hydrogen storage material at supercritical temperatures. ACS Nano, 9 (8), 8249-8254. (doi:10.1021/acsnano.5b02623).

Abstract

(Graph Presented). 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.

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Contributors

Author: Nuno Bimbo

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