Hydrogen Adsorption on Ti–V Binary and Ti–V–Al Ternary Alloys of Ti11 Cluster

Aiming to unravel the effect of alloying on the hydrogen adsorption mechanism, we perform a comparative analysis of the sequential hydrogen loading over Ti11, binary Ti10V, and Ti6VAl4 ternary alloy clusters. For each cluster, the variation of adsorption energy as a function of hydrogen atom coverage was calculated up to 20 hydrogen molecules. The results show that the adsorption of H2 on pure and alloy clusters occurs in a similar fashion including three phases; (i) three-fold and subsequent two-fold dissociative adsorption, (ii) non-dissociative hydrogen adsorption through the Kubas interaction, (iii) non-dissociative physisorption. Our calculations reveal that Ti11, binary Ti10V, and Ti6VAl4 can adsorb at least 20 H2 molecules with the adsorption energies in the range of chemisorption and physisorption. The gravimetric density of H2 adsorbed on these clusters exceeds the ultimate 7.5 wt% limits, recommended for practical applications. However, the magnitude of adsorption energies for Ti6VAl4 are much smaller than those of pure Ti11 binary Ti10V clusters that favor its operating as hydrogen storage media around ambient temperature and pressure.