International Journal of Hydrogen Energy, Vol.45, No.3, 2105-2118, 2020
The optimal adsorption pathway of H-2 molecules on Ti-Acetylene/ethylene compounds: A DFT study
Ti-Acetylene/Ethylene complexes were used to be considered as a potential high capacity hydrogen storage media by physisorption. Here, special attentions have been paid to the optimal adsorption pathway of H-2 molecules on TiC2H2/TiC2H4 compounds by using CCSD(T) and B3LYP functionals. An interesting result is that some most stable configurations of TiC2H2(nH(2))(n = 1-7) complexes are not the structures coordinated by H-2 molecules but plausible hydrogenation intermediates. Based on the potential energy profiles and MD simulations, the optimal adsorption pathway is considered as TiC2H2(T) -> 1b -> 2c -> 2b -> 2a -> 3b -> 3a -> 4a -> 5a -> 5b -> 6d -> C2H6 + Ti(H-2)(5) for TiC2H2 and TiC2H4(1c) -> 2a -> 3b -> 3a -> 4a -> 5a -> 5b -> 6d -> C2H6+Ti(H-2)(5) for TiC2H4. It indicates that the adsorptions of H-2 molecules on TiC2H2/TiC2H4 contain chemisorption and physisorption. The product C2H6+Ti(H-2)(5) exhibits 14 wt% uptake of H-2, which is completely consistent with the experimental results. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.