Stability and Hydrogen Storage Properties of M x -B 6 H 6 Complexes (M = Y–Mo, Ru–Ag, x = 1–2)

The stability and hydrogen storage ability of M x -B 6 H 6 complexes (M = Y–Mo, Ru–Ag, x = 1–2) have been determined. Due to high stability, reversible average adsorption energy, satisfactory gravimetric density, and ambient operating conditions Y complexes are the most promising hydrogen storage materials. Y-B 6 H 6 and Y 2 -B 6 H 6 bind 5 and 12 H 2 molecules, respectively, with the respective gravimetric densities of 5.93 and 8.86 wt %. Their average adsorption energy (Δ E ave ) (0.25 eV/H 2 ) shows that Y compounds can bind hydrogen molecules by reversible adsorption. Zr and Nb elements can also bind multiple H 2 molecules with high gravimetric capacity and reversible average adsorption energy, however, the storage capacities of their dimerization are not satisfactory. Other transition-metal complexes are not suitable to adsorb hydrogen molecules because of their high binding energies or low gravimetric densities.