Hydrogen storage in magnesium decorated boron clusters (Mg2Bn, n = 4–14): A density functional theory study

Abstract

The capacity of hydrogen adsorption of magnesium (Mg) decorated small boron (B) clusters (Mg2Bn; n = 4–14) was studied using density functional theory (DFT). The calculated results indicate that H2 adsorbed in the molecular form. The Bader's topological analysis indicates the presence of closed shell type interaction between clusters and H2 molecules. The clusters are stable even after the adsorption of H2 molecules. The average energy of H2 adsorption is calculated to be in the range of 0.13–0.22 eV/H2. The Mg2B6 cluster shows maximum H2 adsorption (8.10 wt%) at ambient temperature and pressure. Further, we have performed molecular dynamic (MD) simulation at room temperature for each cluster to understand adsorption and desorption of H2 molecules with time. The MD simulation revealed that most of the adsorbed H2 molecules moved away from the clusters within 200 fs. However, one H2 molecule remains attached with the Mg2B11 cluster even after 200 fs.