First-principles investigation of hydrogen storage capacity, electronic, optical, mechanical, and thermodynamic properties of alkaline-metal-based K₂LiXH₆ (X = Mg, Ca) hydrides.
8 affiliations
- 1Department of Physics, Division of Science and Technology, University of Education Lahore Punjab 54770 Pakistan [email protected].
- 2Department of Chemistry, College of Sciences, Princess Nourah bint Abdulrahman University (PNU) PO Box 84428 Riyadh 11671 Saudi Arabia.
- 3Department of Science and Technology, University College at Nairiyah, University of Hafr Al Batin (UHB) Nairiyah 31981 Saudi Arabia.
- 4Department of Physics, College of Science, Qassim University Buridah 51452 Saudi Arabia.
- 5Center for Scientific Research and Entrepreneurship, Northern Border University 73213 Arar Saudi Arabia.
- 6Physics Department, Faculty of Science, Islamic University of Madinah Madinah 42351 Saudi Arabia.
- 7Basic and Applied Scientific Research Center, Imam Abdulrahman Bin Faisal University P. O. Box 1982 Dammam 31441 Saudi Arabia.
- 8Department of Physics, College of Science, Imam Abdulrahman Bin Faisal University P. O. Box 1982 Dammam 31441 Saudi Arabia.
Abstract
Double perovskite hydrides have been identified as promising candidates in solid-state hydrogen storage applications. In the current study, we have explored the structural, hydrogen storage, electronic, optical, mechanical, and thermodynamic characteristics of K₂LiMgH₆ and K₂LiCaH₆. Their structural and thermodynamic stability is demonstrated by the tolerance factors (0.93 and 0.92) being near unity and negative enthalpies of formation (-0.33 and -0.28 eV). Moreover, thermal and dynamic stability are also ensured by AIMD simulations and positive frequencies of phonon band structures. Their gravimetric hydrogen storage capacities are determined to be 5.23 wt% and 4.61 wt%, with corresponding desorption temperatures of 245 K and 208 K, respectively. The electronic analysis shows semiconducting character for K₂LiMgH₆ and metallic character for K₂LiCaH₆, with electronic states crossing the Fermi level. The existence of a finite bandgap guarantees that optical absorption will begin in the UV, which is advantageous for controlled photon-assisted hydrogen release. The mechanical aspects show their brittle nature, with well-defined thermodynamic properties. These results, combined with favorable thermodynamic and hydrogen storage characteristics, establish K₂LiMgH₆ and K₂LiCaH₆ as potential materials for next-generation hydrogen storage technologies. The mineral derived elements (Mg, Ca) tune the hydrogen storage capacity and other physical aspects.
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BibTeX
@article{siddique2026firstprinciples,
title = {{First-principles investigation of hydrogen storage capacity, electronic, optical, mechanical, and thermodynamic properties of alkaline-metal-based K₂LiXH₆ (X = Mg, Ca) hydrides.}},
author = {Kirran Siddique and Ghulam M Mustafa and Murefah Mana Al-Anazy and Noura Dawas Alkhaldi and Abdelkareem Almeshal and Ali El-Rayyes and Mohd Taukeer Khan and Q Mahmood},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08143f},
url = {https://europepmc.org/article/MED/42921234},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - First-principles investigation of hydrogen storage capacity, electronic, optical, mechanical, and thermodynamic properties of alkaline-metal-based K₂LiXH₆ (X = Mg, Ca) hydrides.
AU - Kirran Siddique
AU - Ghulam M Mustafa
AU - Murefah Mana Al-Anazy
AU - Noura Dawas Alkhaldi
AU - Abdelkareem Almeshal
AU - Ali El-Rayyes
AU - Mohd Taukeer Khan
AU - Q Mahmood
PY - 2026
DA - 2026/10/23
JO - RSC advances
DO - 10.1039/d6ra08143f
UR - https://europepmc.org/article/MED/42921234
AB - Double perovskite hydrides have been identified as promising candidates in solid-state hydrogen storage applications. In the current study, we have explored the structural, hydrogen storage, electronic, optical, mechanical, and thermodynamic characteristics of K₂LiMgH₆ and K₂LiCaH₆. Their structural and thermodynamic stability is demonstrated by the tolerance factors (0.93 and 0.92) being near unity and negative enthalpies of formation (-0.33 and -0.28 eV). Moreover, thermal and dynamic stability are also ensured by AIMD simulations and positive frequencies of phonon band structures. Their gravimetric hydrogen storage capacities are determined to be 5.23 wt% and 4.61 wt%, with corresponding desorption temperatures of 245 K and 208 K, respectively. The electronic analysis shows semiconducting character for K₂LiMgH₆ and metallic character for K₂LiCaH₆, with electronic states crossing the Fermi level. The existence of a finite bandgap guarantees that optical absorption will begin in the UV, which is advantageous for controlled photon-assisted hydrogen release. The mechanical aspects show their brittle nature, with well-defined thermodynamic properties. These results, combined with favorable thermodynamic and hydrogen storage characteristics, establish K₂LiMgH₆ and K₂LiCaH₆ as potential materials for next-generation hydrogen storage technologies. The mineral derived elements (Mg, Ca) tune the hydrogen storage capacity and other physical aspects.
SN - 2046-2069
ER -