Na-coated hexagonal B36 as superior hydrogen storage materials

Based on van der Waals corrected density functional theory, we show that Na atoms acting as decoration metals are not inclined to form clusters due to a large binding energy of 3.31 eV, indicating a promising good reversible hydrogen storage. Both the polarization mechanism and the orbital hybridizations contribute to the adsorption of hydrogen molecules (storage capacity of 4.4 wt%) with optimal adsorption energy of 0.25 eV/H2. Additionally, the dimerization of these isolated B36 does not remarkably affect the number of adsorbed H2 per Na atom. Our results may serve as a guide in the design of new hydrogen storage materials based on low-dimension boron clusters.