Titanium Atoms-Decorated B40 Fullerene: First-Principle Study to Predict the Structural Evolution During Hydrogen Storage

Boron-based nanostructures are considered as alternative hydrogen storage material due to its large surface area, lightweight and chemical stability. In this work, the hydrogen storage capacity and structural evolution of titanium (Ti) atoms-decorated B40 fullerene are investigated using first-principles calculations. Our result shows that Ti prefers to absorb on the outside surface of the hexagonal and heptagonal cavities of B40 ring. The average binding energy (Ebinding) for 6 Ti atoms-decorated B40 structure is calculated as 5.71 eV. The interatomic distance between two neighbor Ti atoms (5.13–5.54 Å) is larger than that of Ti2 dimer (~ 2.0 Å) to prevent the aggregation of Ti atoms as well as Tin cluster formation. The average adsorption energies (Eadsorption) for (Ti–nH2)6B40 (n = 2–6) structures, within a range of 0.29–0.33 eV, prove that the structures are between chemisorbed and physisorbed states (0.2–0.6 eV). We have achieved a maximum gravimetric density (H2 wt%) of 9.3 wt% exceeding the 5.5 wt% goal set by the Department of Energy, USA, by the year 2020. In addition, ab initio molecular dynamics calculations have confirmed that the (Ti–6H2)6B40 structure is stable for the hydrogen adsorption under near-ambient temperature.