An aromatic Ca2B8 complex for reversible hydrogen storage

Ca2B8 cluster which shows high stability is predicted to be a symmetrical 3-dimension complex at coupled-cluster method. Charge analysis shows that the great charge transfers from Ca to B8 ring result in the formation of (Ca)22 thorn (B8)4- complex. The aromaticity of this complex is identified through the negative nucleus-independent chemical shifts (NICS) and delocalized s and p molecular orbitals. Importantly, the aromatic Ca2B8 is found to be a promising hydrogen storage material with moderate adsorption energy and high gravimetric density (10.6%). The adsorbed H2 molecules on Ca2B8 can be efficiently released at ambient temperature revealed by ab initio molecular dynamics (AIMD) simulation. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The Ca2B8 cluster is predicted to be a stable symmetrical 3-dimension complex with aromaticity, showing potential as a hydrogen storage material with high adsorption energy and gravimetric density. The charge analysis and molecular orbital studies reveal the mechanism of formation and release of the adsorbed H2 molecules on Ca2B8.