The optimal adsorption pathway of H2 molecules on Ti-Acetylene/ ethylene compounds: A DFT study

Abstract

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 H2 molecules on TiC2H2/TiC2H4 compounds by using CCSD(T) and B3LYP functionals. An interesting result is that some most stable configurations of TiC2H2(nH2)(n = 1–7) complexes are not the structures coordinated by H2 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(H2)5 for TiC2H2 and TiC2H4(1c) → 2a → 3b → 3a → 4a → 5a → 5b → 6d → C2H6+Ti(H2)5 for TiC2H4. It indicates that the adsorptions of H2 molecules on TiC2H2/TiC2H4 contain chemisorption and physisorption. The product C2H6+Ti(H2)5 exhibits 14 wt% uptake of H2, which is completely consistent with the experimental results.