The study of the hydrogen storage capacity of the Ti atoms coated Si@Ga-12 clusters

摘要

The generalized gradient approximation based on the density functional theory method is used to investigate the hydrogen storage abilities of the transition metal Ti atoms coated Ti-m-Si@Ga-12 (m = 1, 2) clusters. The average binding energy of the Ti atom to the hollow site on the Si@Ga-12 surface and the distance between the neighboring two Ti atoms are 5.20 eV and 2.8 angstrom, respectively larger than the experimental cohesive energy of bulk Ti (4.85 eV/atom) and the experimental bond length of the Ti-2 dimer (1.97 angstrom), so the clustering of Ti atoms can be prevented, this is critical for large amount hydrogen storage. Ti-Si@Ga-12 and Ti-2-Si@Ga-12 can adsorb 6 and 12H(2) molecules separately with the average adsorption energy of 0.37 eV and 0.30 eV, which would allow hydrogen storage at near-ambient conditions. The Dewar-Kubas interaction mechanism dominates the adsorption of H-2 by the Ti-Si@Ga-12 and Ti-2-Si@Ga-12 structures. The average desorption temperature analysis and the molecular dynamic simulation demonstrate that the structures reported here are favorable for the reversible hydrogen storage at near-ambient conditions. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.