H2 storage capacity of Li-doped five member aromatic heterocyclic superalkali complexes; an in silico study

Abstract

Hydrogen adsorption characteristics of different Li dopped aromatic five-membered heterocyclic (Ar) systems; have been studied [Ar = Imidazole, Pyrazole, Oxazole, Isoxazole, Thiazole, and Isothiazole]. The Lithiated heterocyclic systems are stabilized as cation (Ar-Li)+ and behave as superalkali (the vertical electron affinity (VEA) value ranges from 4 − 1.99 eV). The bonding nature between Ar and Li as well as that between Li and adsorbed H2 molecule has been analyzed through the electron localization function (ELF) study. The first principle calculation reveals that (Ar-Li)+ complexes can adsorb up to five molecular hydrogens in a quasi-sorption way with the binding energy of ∼ −2.17 eV. The spontaneity of the hydrogen adsorption in (Ar-Li)+ complexes is studied to find in which temperature Gibbs free energy change (ΔG) for all H2 adsorbed systems will be negative. At 80 K temperature, it will be satisfied.