Hydrogen storage in Na decorated heteroborospherene Si4B32: Insights from density functional study

Abstract

This article investigates the structural stability and hydrogen adsorption performance of Na-decorated heteroborospherene Si4B32 using density functional theory (DFT) methods. DFT calculations demonstrate that six sodium (Na) atoms can successfully and chemically bind to the surface of heteroborospherene Si4B32, exhibiting a substantial average binding energy of 2.465 eV without clustering. Moreover, the resulting Na6Si4B32 structure retains its integrity even after absorbing up to 30 hydrogen (H2) molecules, with an average adsorption energy of 0.251 eV/H2. Utilizing DFT analysis, the gravimetric density of Na6Si4B32·(H2)30 can reach 9.143 wt%. Additionally, employing ab initio molecular dynamics (AIMD) simulations, we find that a significant fraction of the H2 molecules desorb from Na6Si4B32 at 300K within 1000 fs. These findings establish the potential of Na-decorated heteroborospherene Si4B32 as a promising candidate for reversible hydrogen storage. The successful binding of Na atoms without clustering and the substantial H2 adsorption capacity, coupled with the structural stability and facile H2 desorption observed at moderate temperatures, highlight the viability of this material for practical hydrogen storage applications.