Linear complex HC[tbnd]C-TMH (TM=Sc–Ni): A simple and efficient adsorbent for hydrogen molecules

Abstract

The structure and hydrogen adsorption properties of linear HCC-TMH (TM = Sc–Ni) complexes were systematically investigated using a density functional method. The ground states of the HCC-TMH (TM = Sc–Ni) complexes are 2, 3, 4, 3, 4, 3, 2, and 3. The gravimetric H2 uptake capacities of these ground state HCC-TMH (TM = Sc–Ni) complexes are 4.54–14.56%. Ab initio molecular dynamic simulations indicated that maximal reversible hydrogen storage densities at 77–300 K of the ground state HCC-TMH (TM = Ti–Co) complexes are 6.65–12.00 wt%. The corresponding average adsorption energies are 0.07–0.49 eV. Due to reasonable superior storage capacity and ideal binding energy, HCC-TMH (TM = Ti–Co) complexes are proposed as a suitable hydrogen storage medium at ambient conditions.When HCC-TMH (TM = Ti, V, Cr) are nonground state structures, they can adsorb one more H2 molecule than their ground states. Unfortunately, the first adsorbed H2 molecules are dissociated and the adsorption energies are too large. Therefore, the importance of the multiplicity of sorbents for hydrogen storage is emphasized in this work.