Transition metal Ti coated porous fullerene C24B24: Potential material for hydrogen storage

Total 12 carbon atoms of six equivalent C-C bonds of C60 are removed and 24 carbon atoms in six rings are replaced by boron atoms, generating the C24B24 cage. Six Ti atoms are located on the hollow site of six B4 rings. The calculated binding energy (Eb) of Ti6C24B24 at the Perdew-Burke-Ernzerhof functional based on the generalized gradient approximation (PBE/GGA) level is 8.58 eV, which is larger than the corresponding experimental metal cohesive energy (6.43 eV at the PBE/GGA method). Therefore, the problem of the Ti atoms aggregative to form cluster is expected to be overcome, and the material will be stable for designing a recyclable hydrogen material. It is known from the consecutive adsorption energy (Er) that each Ti atom can adsorb 6 hydrogen molecules at absolute zero temperature. The average binding energy per atom (Ead/H2) of (Ti-nH2)6C24B24(n = 1-6) basing on the PBE/GGA method are between 0.24 and 0.55 eV, which is between physisorbed and chemisorbed states, so Ti6C24B24 should be a good candidate for reversible hydrogen storage at near-ambient conditions.179