Metal-functionalized silicene for efficient hydrogen storage

First-principles calculations based on density functional theory are used to investigate the electronic structure along with the stability, bonding mechanism, band gap, and charge transfer of metal-functionalized silicene to envisage its hydrogen-storage capacity. Various metal atoms including Li, Na, K, Be, Mg, and Ca are doped into the most stable configuration of silicene. The corresponding binding energies and charge-transfer mechanisms are discussed from the perspective of hydrogen-storage compatibility. The Li and Na metal dopants are found to be ideally suitable, not only for strong metal-to-substrate binding and uniform distribution over the substrate, but also for the high-capacity storage of hydrogen. The stabilities of both Li- and Na-functionalized silicene are also confirmed through molecular dynamics simulations. It is found that both of the alkali metals, Li+ and Na+, can adsorb five hydrogen molecules, attaining reasonably high storage capacities of 7.75 and 6.9 wt %, respectively, with average adsorption energies within the range suitable for practical hydrogen-storage applications. Hoovering up hydrogen: A systematic density functional theory investigation shows alkali-metal doped silicene to be a promising hydrogen-storage material. The preferential sites of the dopants, stabilities of the doped systems, the bonding mechanism, and the hydrogen storage capacities are calculated by using a variety of computational methods including the projector augmented wave method, the Perdew-Burke-Ernzerhof variant of the generalized gradient approximation, the Nosé-Hoover thermostat, and Bader charge analysis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.