Enhancement of adsorption on a boron-doped carbon system for hydrogen storage

We study the adsorption of the molecular hydrogen on boron-doped polypyrrole ((–C4BH3)n) using first-principles density functional calculations. We find that the binding energy of H2 molecules is slightly reduced to 0.39 eV/H2 from 0.51 eV/H2 as the number of adsorbed H2 molecules increases. This is in sharp contrast to the case of boron-doped fullerenes where the binding energy is drastically reduced as the number of adsorbed H2 molecules increases. We find that the enhancement of H2 adsorption is due to a local charge transfer by H2 adsorption in the B-doped polypyrrole as opposed to a delocalized charge transfer in the B-doped fullerenes. Our finding shows that B-doped carbon systems could be utilized for room temperature hydrogen storage.