Ca-decorated novel boron sheet: A potential hydrogen storage medium

We studied hydrogen storage properties of Ca-decorated a novel boron sheet through first-principles calculations. It was found that up to six H₂ molecules can be captured by a Ca atom at 0 K with an average binding energy in a better range of ‑0.20 to ‑0.32 eV/H₂. The gravimetric hydrogen density of 12.68 wt.% is reached when Ca is adsorbed on both sides of the boron sheet. The mechanism for binding the attached H₂ molecules comes from not only the polarization mechanism but also the orbital hybridization. The effect of temperature and pressure on hydrogen storage performance of the Ca-decorated boron sheet was also evaluated. At room temperature, all the hydrogen adsorbed structures are stable at mild pressure. Our results indicate that Ca-decorated boron sheet is a potential hydrogen storage medium for on-board vehicle application.