[SY-E8] Symposium E-8

[SY-E8] DFT predictions of hydrogen storage properties of Mg₇TiX₂ (X= F, O, S, P and Cl)

^○Yuying Chen, Jianhong Dai, Yan Song (School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, China)

Stability and reversibly de/hydrogenation properties of presumed Mg₇TiX₂ (X= F, O, S, P and Cl) were predicted using Density Functional Theory. Hypothetical Mg₇TiX₂ and its hydride are energetically stable with respect to the individual elements involved and they may be synthesized experimentally. The stability of alloy highly relate to the formation energy of Mg-X compound because that distance of Ti-X is large than that of Mg-X. The considered systems possess preferable hydrogen adsorbing capacity, and their hydrogen adsorption energies lie in the range from -0.5 eV to -0.05 eV. The dehydrogenation of the Mg₇TiX₂H₁₄ were calculated and found that H-Mg bond and Ti-Mg bond have significant effect on dehydrogenation process. The study of desorption energy of X atoms found that P atoms are less stable than H atoms and will escape from system before H atoms that lead system collapse, thus Mg₇TiP₂ is not available to hydrogen storage. Our studies indicated that Mg₇TiX₂ (X= F, O, S and Cl) can realize reversible hydrogen storage properties.



Keywords: Density Functional Theory; Hydrogen Storage; Stability; Reversibility; Mg₇TiX₂.