Exploring physical and hydrogen storage properties of the dynamically stable ATi3H8 (A = Al, In, Tl) hydrides: A first-principles study

초록

This study comprehensively investigated the structural, electronic, mechanical, optical, thermodynamic, and hydrogen storage abilities of three newly proposed complex hydrides: AlTi3H8, InTi3H8, and TlTi3H8. First-principles calculations were carried out within the framework of Density Functional Theory (DFT) using the CASTEP package, utilizing both the Generalized Gradient Approximation (GGA-PBE) and the Hybrid HSE06 functionals. The obtained results confirmed that all three compounds are stable in a cubic Pm-3m phase. Thermodynamic stability is established by negative formation energies ranging between -0.227 eV/atom and -0.428 eV/atom. The electronic band structure reveals that the three compounds are metallic, with Ti-3d states being dominant at the Fermi level. Mechanically, all three compounds satisfy the Born stability criteria and exhibit a ductile nature, with AlTi3H8 emerging as the stiffest material. Furthermore, stability at 300 K was confirmed. AlTi3H8 also demonstrates the highest hydrogen storage potential, offering a gravimetric capacity of 4.48 wt% and a volumetric capacity of 156.8 g H2/L at desorption temperature of 243.61 K, close to the requirements of U.S. DOE. © 2026 The Physical Society of the Republic of China (Taiwan).

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