Substitution of nickel in Mg2Ni and its hydride with elements from groups XIII and XIV: An ab initio study

0541845 - ÚFM 2022 RIV GB eng J - Journal Article
Káňa, Tomáš - Čermák, Jiří - Král, Lubomír
Substitution of nickel in Mg2Ni and its hydride with elements from groups XIII and XIV: An ab initio study.
International Journal of Hydrogen Energy. Roč. 46, č. 29 (2021), s. 15691-15701. ISSN 0360-3199. E-ISSN 1879-3487
R&D Projects: GA ČR(CZ) GA17-21683S; GA MŠMT(CZ) LQ1601
Institutional support: RVO:68081723
Keywords : Energy storage materials * Hydrogen absorbing materials * Metal hydrides * Computer simulation * Ab initio
OECD category: Materials engineering
Impact factor: 7.139, year: 2021
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0360319921004730?via%3Dihub

We have performed ab initio calculations with equilibrium supercells of the Mg2Ni compound and its hydride Mg2NiH4 doped with elements X = Al, Ga, In, Si, Ge and Sn. Two concentrations of X in both structures have been set: (1) every 16th, and (2) every fourth Ni atom has been substituted by X. Total energy calculations yielded the Mg2NiH4 hydrogen absorption enthalpy ΔHabs according to the chemical reaction Mg2Ni + 2H2 → Mg2NiH4. Reduction of the hydrogen absorption enthalpy was reported for both concentrations of X. When doping the Mg2NiH4 hydride with X = In in a low concentration (1), the value of hydrogen desorption enthalpy decreases from 68.22 to 55.96 kJ(mol H2)−1. Doping with X = In in a high concentration (2) further decreases the hydrogen desorption enthalpy to 5.50 kJ(mol H2)−1. Further, the electronic structure of Mg2(Ni–In)H4 hydride with a low In concentration indicates weaker Ni–H bonds in comparison with the pristine Mg2NiH4. Attraction between H and In atoms induced enhanced bonding between Mg and H atoms compared to the pristine Mg2NiH4.
Permanent Link: http://hdl.handle.net/11104/0319904