A first principle study of hydrogen storage in titanium-doped small carbon clusters (C2nTin, n = 2–6)

Abstract

Hydrogen storage in Ti-doped small carbon clusters, C2nTin (n = 2–6), has been studied using density functional theory. Using the principle of maximum hardness (η) and minimum electrophilicity (ω), stabilities of the clusters are confirmed. The average adsorption energies of all complexes are found in the range of 0.2–0.5 eV/H2 and average Ti-H2 bond length is in the range of 1.953 to 2.145 A, inferring the adsorption process to be physisorption type. All the studied clusters are found to adsorb hydrogen in molecular form through Kubas type of interaction with H2 uptake capacity in the range of 5.31–10.09 wt% which is well above the target set by US-DOE (5.5 wt%). Bader’s topological analyses confirm the closed-shell type interaction among H2 molecules and Ti atoms. Desorption temperature calculated using Van’t-hoff equation is found above the liquid nitrogen temperature.