Hydrogen is considered a safe and clean alternative to fossil fuels. Hydrogen storage is currently obtained by compressing the gas at high pressure. Researchers are currently attempting to tackle safety and energy density issues by locking hydrogen into solids, packing large quantities into small volumes. However, most of the known solids (i.e. intermetallics) show very low gravimetric density, smaller than 2 wt% of H2. Lither materials (i.e. complex hydrides) can only absorb hydrogen under extreme temperature and pressure conditions.