Alkali, alkaline earth and transition metal doped B 6 H 6 complexes for hydrogen storage

Alkali, alkaline earth and transition metal doped B 6 H 6 complexes are considered for the hydrogen storage. Density functional theory (DFT) and second order Møller–Plesset methods with 6–311++G** basis set have been used for the study. B 6 H 6 Li, B 6 H 6 Be, B 6 H 6 Sc, B 6 H 6 Li 2, B 6 H 6 Be 2, B 6 H 6 Sc 2 complexes can interact with maximum three, two, four, six, four and eight H 2 molecules respectively with respective H 2 uptake capacity of 7.2, 4.8, 6.5, 12.5, 8.3 and 9.1 wt%. This uptake capacity is well above the target set by the U.S. Department of Energy by 2020 except for the B 6 H 6 Be complex. Thermo chemistry calculations are carried out to estimate the Gibbs free energy corrected H 2 adsorption energy which reveals whether adsorption of hydrogen on these complexes is favourable or not at different temperature. It is observed that H 2 adsorption on all the six complexes are unfavourable at ambient conditions where as it is favourable below 150, 135, 75, and 50 K on B 6 H 6 Sc, B 6 H 6 Be, B 6 H 6 Li and B 6 H 6 Li 2 complexes respectively. Various interaction energies in H 2 adsorbed complexes are obtained using Many-body analysis approach. The H 2 desorption temperature for the B 6 H 6 Li, B 6 H 6 Be, B 6 H 6 Sc, B 6 H 6 Li 2, B 6 H 6 Be 2 and B 6 H 6 Sc 2 complexes is found to be 25, 165, 265, 10, 265 and 373 K respectively.