Computational investigation and comparison of hydrogen storage properties of B24N24 and Al24N24 nanocages


SAYHAN S., KINAL A.

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, vol.42, no.20, pp.14166-14180, 2017 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 42 Issue: 20
  • Publication Date: 2017
  • Doi Number: 10.1016/j.ijhydene.2017.04.069
  • Title of Journal : INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
  • Page Numbers: pp.14166-14180

Abstract

In this study, hydrogen storage properties of the B24N24 and Al24N24 nanocages have been computationally investigated by the DFT method whose suitability was determined with a thorough methodological analysis. This analysis includes comparison of the performances of a number of DFT functionals against the CCSD(T) method for the determination of the best DFT method that is able to accurately model H-2-BN and H-2-AlN systems. The (sic)B97X-D, B3LYP-D2, PBEPBE-D2, BHandH methods produced results close to that of the reference CCSD(T) method. Of all methods studied, (sic)B97X-D, showing the best performance, is found to be the most appropriate DFT method for H-2-B24N24 and Al24N24 systems including dispersive interactions between hydrogen and the host molecule. The (sic)B97X-D calculations result in that H2 molecule make the tightest adsorptive bond with Al atom in Al24N24 having an adsorption energy of 0.116 eV, by forming much more stable complex than the H-2-B24N24 one. This indicates that Al24N24 has better exohedral hydrogen storage properties. The calculations also revealed that H2 molecules cannot pass through hexagonal rings of B24N24 instead they chemisorb on the cage atoms by breaking BN bond while they can pass through hexagonal rings of Al24N24 without making any damage in the Al-N bond, leading the fact that the Al-N bond is stronger than the B-N bond. Moreover, endohedral addition of H-2 molecules up to three can form thermodynamically stable nH(2)@Al24N24 complexes while endohedral hydrogen addition to B24N24 destabilizes the complexes. Thus, the Al24N24 nanocage is not only structurally more stable than B24N24 nanocage, but also it can accommodate more hydrogen molecules, so it is better candidate for both endohedrally and exohedrally hydrogen storage compared to B24N24. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.