1. Ab-initio study of hydrogen mobility in the vicinity of MgH2[sbnd]Mg interface: The role of Ti and TiO2
- Author
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Simone Giusepponi, Massimo Celino, Radojka Vujasin, Nikola Novaković, Jasmina Grbović Novaković, and Celino, M.
- Subjects
Materials science ,Hydrogen ,Interfaces ,Ab initio ,chemistry.chemical_element ,Ionic bonding ,Nanotechnology ,02 engineering and technology ,Electronic structure ,01 natural sciences ,Ab–initio calculation ,Condensed Matter::Materials Science ,Molecular dynamics ,Dopants ,Desorption ,0103 physical sciences ,Oxidation ,Physics::Atomic and Molecular Clusters ,Materials Chemistry ,010306 general physics ,Dopant ,Hydrogen desorption ,Hydrogen storage ,Ab–initio calculations ,ab initio calculations ,Mechanical Engineering ,Doping ,Metals and Alloys ,Interface ,021001 nanoscience & nanotechnology ,3. Good health ,chemistry ,Mechanics of Materials ,Chemical physics ,0210 nano-technology - Abstract
Doping of MgH2 with transition metals and their oxides is well-known procedure to improve its hydrogen (de) sorption properties, namely to lower the temperature of desorption and to achieve the kinetics speedup. In order to assess the influence Ti and TiO2 doping has on H mobility and to characterize structurally and electronically observed differences, MgH2-Mg interface doped with both Ti and TiO2 have been studied using ab-initio interface molecular dynamics and bulk calculations. Results suggest different mechanisms of MgH2 structure destabilization. The presence of dopants significantly stabilize MgH2-Mg interface, which is confirmed by work of adhesion computation. Calculated formation energies show that interface system with doped TiO2 is more stable. In terms of H mobility, molecular dynamics simulations confirm that Ti doping is more effective than TiO2 in lowering the desorption temperature. The mobility of hydrogen atoms close to dopant is much higher in the case of Ti than in the case of TiO2. Electronic structure characterization reveals that oxygen atoms with high electron affinity forms more pronounced ionic bonding with Ti and the other neighbor Mg atoms. This in turn cause a shorter Ti-H bonds in first coordination than in the case of Ti doping and further reduction of H atoms mobility. This is in accordance with molecular dynamics predictions. (C) 2016 Elsevier B.V. All rights reserved.
- Published
- 2017