A first-principle study on hydrogen storage of metal atoms (M = Li, Ca, Sc, and Ti) coated B40 fullerene composites

By means of density functional calculations, we design four hydrogen storage materials, 6Li@B-40, 6Ca@B-40, 6Sc@B-40, and 6Ti@B-40 composites, and perform a comprehensive study on hydrogen adsorption and storage. It is found that 6Ca@B-40 is the best candidate for hydrogen storage with moderate adsorption energy of H-2. The clustering of Ca on B-40 surface is avoided, owing to the strong binding between Ca and B-40. 6Ca@B-40 can store up to 24 H-2 molecules through physical absorption mainly and with an average adsorption energy of 0.170 eV/H-2, corresponding to a gravimetric density of 6.66 wt%.