Ab initio study on destabilizing mechanism of magnesium hydride by Ti and Fe co-doping

摘要

A first-principle calculation based on density functional theory (DFT) was performed to study the destabilizing mechanism of Ti and Fe co-doped MgH2. The calculated heats of formation show that Ti and Fe co-doped MgH2 system is thermo-dynamically favorable for practical hydrogen storage. The doping of Fe combined with Ti into the MgH2 rutile type structure is more energetically favorable relative to Fe single-doping into the same structure. We calculated the electronic structure, bond lengths and Bader atomic charges of the co-doped system and compared with those of the pure MgH2. Based on phonon calculation, we also estimated the thermo-dynamical properties such as entropy and specific heat capacity as well as lattice vibrations. The obtained results indicate that Ti and Fe co-doping is an effective method in order to destabilize magnesium hydride. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.