Adsorption Mechanism of Hydrogen on Boron-Doped Fullerenes

The C₃₅BH-H₂ complex and two other possible isomers, C₃₄BC_aH-H₂ and C₃₄BC_bH-H₂, are investigated using the local-spin-density approximation (LSDA) method. The results indicate that a single hydrogen molecule could be strongly adsorbed on two isomers, C₃₄BC_aH and C₃₄BC_bH, with bindingenergies of 0.42 and 0.47eV, respectively, and that these calculated binding energies are suitable for reversible hydrogen adsorption/desorption near room temperature. However, it is difficult for the H₂ molecule to be firmly adsorbed on C₃₅BH. We analyze the interaction between C₃₄BC_xH (x=a, b) and the H₂ molecule using dipole moments and molecular orbitals. The charge analysis showed there was a partial charge (about 0.32e) transfer from H₂ to the doped fullerenes. These calculation results should broaden our understanding of the mechanisms of hydrogen storage using boron-doped fullerenes.