Vibrational spectra of Ti:C2H4(nH2) and Ti:C2H4(nD2) (n = 1–5) complexes and the equilibrium isotope effect: Calculations and experiment

Calculations of the ability of titanium–ethylene complexes of the type, Ti:C2H4, to absorb molecular hydrogen have been performed using density functional theory. A maximum of 5H2 molecules can be adsorbed on Ti:C2H4 thereby giving an uptake capacity of 11.72 wt%, in excellent agreement with previous experimental results reported by two of us (Phys. Rev. Lett., 100, 105505, 2008). Calculations of the vibrational frequencies in such complexes with both H2 and D2, Ti:C2H4(nH2) and Ti:C2H4(nD2), n = 1–5, have also been performed and the values obtained used to find the Equilibrium Isotope Effect (EIE). Measurements of the EIE are also reported and these are in excellent agreement with the EIE calculated for 5H2 molecules adsorbed in the complex.

► Lightweight Ti:C2H4 material for hydrogen storage. ► Excellent agreement between H2 uptake capacity from the theory and experiment. ► Equilibrium isotope effect from theory and experiment is 0.66. ► Potential application in the area of hydrogen storage for vehicular application.