Nanoporous materials have attracted great attention for gas storage, but achieving high volumetric storage capacity remains a challenge. Here, by using neutron powder diffraction, volumetric gas adsorption, inelastic neutron scattering and first-principles calculations, we investigate a magnesium borohydride framework that has small pores and a partially negatively charged non-flat interior for hydrogen and nitrogen uptake. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores, with very different limiting capacities of 2.33 H2 and 0.66 N2 per Mg(BH4)2. Molecular hydrogen is packed extremely densely, with about twice the density of liquid hydrogen (144?g?H2 per litre of pore volume). We found a penta-dihydrogen cluster where H2 molecules in one position have rotational freedom, whereas H2 molecules in another position have a well-defined orientation and a directional interaction with the framework. This study reveals that densely packed hydrogen can be stabilized in small-pore materials at ambient pressures.
In this work, Dr. Posada-Pérez from IQCC, has been in charge of the first principle simulations, proving that the H2 loading is not sequential otherwise is following a two-phase region loading, due to the formation of stable tri-dihydrogen and penta-dihydrogen clusters that stabilize the host-guest and guest-guest interactions.
The computational part has been carried out in collaboration with Prof. Hautier, and the experiments have been performed by the groups of Prof. Jensen, Prof. Hirscher, and Prof. Filinchuck.
It has been recently published open access in Nature Chemistry Journal:
H. Oh, N. Tumanov, V. Ban, X. Li, B. Richter, M. R. Hudson, C. M. Brown, G. N. Iles, D. Wallacher, S. W. Jorgensen, L. Daemen, R. Balderas-Xicohténcatl, Y. Cheng, A. J. Ramirez-Cuesta, M. Heere, S. Posada-Pérez, G. Hautier, M. Hirscher*, T. R. Jensen*, and Y. Filinchuk*
“Small-pore hydridic frameworks store densely packed hydrogen“
Nat. Chem., 2024, ASAP
DOI: 10.1038/s41557-024-01443-x
Girona, February 16, 2024
For more info: ges.iqcc@udg.edu