Thermodynamically stable Mg2XH6 (X = Al, Si) double perovskite hydrides for high-capacity hydrogen storage: A DFT and AIMD study
5 affiliations
- 1Laboratory of Advanced Materials and Applications (LM2A), Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, B.P.1796 Fez-Atlas, Morocco
- 2Department of Physics, Abou Bakr Belkaid University, Tlemcen 13000, Algeria
- 3Materials Modeling and Simulation Lab, Department of Physics, University of Science & Technology Bannu 28100, Khyber Pakhtunkhwa, Pakistan
- 4Department of Mechanical Engineering, National Taiwan University, Taipei 106319, Taiwan, People’s Republic of China
- 5Department of Applied Mechanics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China
Abstract
• Mg 2 XH 6 (X = Al/Si) double perovskite hydrides investigated via first-principles DFT. • Mechanical and dynamical stability confirmed by Born criteria and phonon spectra. • Metallic electronic structure with strong dielectric response and optical conductivity. • High gravimetric H 2 capacities of 7.41 wt% (Al) and 7.31 wt% (Si) achieved. • Desorption temperatures of 361.7 K (Al) and 368.0 K (Si) predicted. The escalating worldwide demand for decarbonized energy systems has led to hydrogen being established as a leading candidate owing to its high specific energy and environmentally benign combustion profile. Among the advanced materials for solid-state hydrogen storage, double perovskite hydrides of Mg 2 XH 6 (X = Al/Si) are a promising class of lightweight compounds. Using density functional theory, this study presents a comprehensive computational analysis of the structural, elastic, mechanical, electronic, optical, thermodynamic, and vibrational properties. Moreover, their thermal stability, finite-temperature dynamics via molecular dynamics simulations, and hydrogen-storage performance were evaluated. Tolerance factor calculations revealed that these hydrides adopt stable cubic perovskite configurations, with their negative formation enthalpies providing additional evidence of thermodynamic stability. All hydrides satisfy Born’s mechanical stability criteria and exhibit high stiffness, superior mechanical strength, enhanced hardness, shear resistance, and ductile mechanical characteristics. Electronic band structure calculations demonstrate that both Mg 2 AlH 6 and Mg 2 SiH 6 exhibit metallic behavior using the generalized gradient approximation (GGA) based on the Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional. Optical analysis revealed a strong dielectric response, pronounced light–matter interaction, and high optical conductivity, along with superior absorption and excellent photonic performance. Phonon dispersion analysis confirmed the dynamic stability of these compounds. Their thermodynamic parameters and high melting points highlight their overall stability and attractive properties. Furthermore, ab initio molecular dynamics (AIMD) simulations provide compelling evidence of the robust thermal stability of these compounds under realistic conditions. Beyond these attributes, assessments of hydrogen storage capacity exhibit impressive gravimetric contents of 7.41 wt% for Mg 2 AlH 6 and 7.31 wt% for Mg 2 SiH 6 values that exceed the U.S. Department of Energy (DOE) 2025 target of 5.5 wt%. These results highlight the strong potential of these compounds as high-capacity hydrogen-storage materials.
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BibTeX
@article{mekkaouy2026thermodynamically,
title = {{Thermodynamically stable Mg2XH6 (X = Al, Si) double perovskite hydrides for high-capacity hydrogen storage: A DFT and AIMD study}},
author = {Abdelghafour El Mekkaouy and Abdellah Hammad and Asif Nawaz Khan and Najat El Gaidi and Tesfaye Abebe Geleta and Younes Mekki and Muhammad Usman and Rodouan Touti},
journal = {Journal of Magnesium and Alloys},
year = {2026},
month = may,
doi = {10.1016/j.jma.2026.102110},
url = {https://doi.org/10.1016/j.jma.2026.102110},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Thermodynamically stable Mg2XH6 (X = Al, Si) double perovskite hydrides for high-capacity hydrogen storage: A DFT and AIMD study
AU - Abdelghafour El Mekkaouy
AU - Abdellah Hammad
AU - Asif Nawaz Khan
AU - Najat El Gaidi
AU - Tesfaye Abebe Geleta
AU - Younes Mekki
AU - Muhammad Usman
AU - Rodouan Touti
PY - 2026
DA - 2026/05/15
JO - Journal of Magnesium and Alloys
DO - 10.1016/j.jma.2026.102110
UR - https://doi.org/10.1016/j.jma.2026.102110
AB - • Mg 2 XH 6 (X = Al/Si) double perovskite hydrides investigated via first-principles DFT. • Mechanical and dynamical stability confirmed by Born criteria and phonon spectra. • Metallic electronic structure with strong dielectric response and optical conductivity. • High gravimetric H 2 capacities of 7.41 wt% (Al) and 7.31 wt% (Si) achieved. • Desorption temperatures of 361.7 K (Al) and 368.0 K (Si) predicted. The escalating worldwide demand for decarbonized energy systems has led to hydrogen being established as a leading candidate owing to its high specific energy and environmentally benign combustion profile. Among the advanced materials for solid-state hydrogen storage, double perovskite hydrides of Mg 2 XH 6 (X = Al/Si) are a promising class of lightweight compounds. Using density functional theory, this study presents a comprehensive computational analysis of the structural, elastic, mechanical, electronic, optical, thermodynamic, and vibrational properties. Moreover, their thermal stability, finite-temperature dynamics via molecular dynamics simulations, and hydrogen-storage performance were evaluated. Tolerance factor calculations revealed that these hydrides adopt stable cubic perovskite configurations, with their negative formation enthalpies providing additional evidence of thermodynamic stability. All hydrides satisfy Born’s mechanical stability criteria and exhibit high stiffness, superior mechanical strength, enhanced hardness, shear resistance, and ductile mechanical characteristics. Electronic band structure calculations demonstrate that both Mg 2 AlH 6 and Mg 2 SiH 6 exhibit metallic behavior using the generalized gradient approximation (GGA) based on the Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional. Optical analysis revealed a strong dielectric response, pronounced light–matter interaction, and high optical conductivity, along with superior absorption and excellent photonic performance. Phonon dispersion analysis confirmed the dynamic stability of these compounds. Their thermodynamic parameters and high melting points highlight their overall stability and attractive properties. Furthermore, ab initio molecular dynamics (AIMD) simulations provide compelling evidence of the robust thermal stability of these compounds under realistic conditions. Beyond these attributes, assessments of hydrogen storage capacity exhibit impressive gravimetric contents of 7.41 wt% for Mg 2 AlH 6 and 7.31 wt% for Mg 2 SiH 6 values that exceed the U.S. Department of Energy (DOE) 2025 target of 5.5 wt%. These results highlight the strong potential of these compounds as high-capacity hydrogen-storage materials.
SN - 2213-9567
ER -