The development of efficient hydrogen storage solutions is crucial for advancing the commercialization of hydrogen-based energy systems. Solid-state hydrogen storage is emerging as a highly promising method, attracting considerable interest and necessitating in-depth research efforts. This study systematically designs six novel solid-state hydrides: K2LiGaH6, K2LiInH6, K2LiTlH6, Rb2LiGaH6, Rb2LiInH6, and Rb2LiTlH6, using density functional theory (DFT). The objective is to thoroughly investigate their structural, elastic, opto-electronic, thermodynamic, and hydrogen storage characteristics. The dynamical stability was analyzed, and the resulting phonon dispersion curves confirm that these materials are stable. Furthermore, ab initio molecular dynamics (AIMD) simulations confirm the thermal stability of the hydrides at room temperature (300 K), as no structural deformation was observed. The band structure indicates that all materials exhibit indirect band gap semi conducting behavior, with band gap values spanning from 0.3 to 2 eV. Optical property analysis reveals that these hydrides are effective ultraviolet absorbers, with a noticeable red shift in the absorption edge can be observed resulting from the variations of bandgap. All the hydrides demonstrate mechanical stability and exhibit brittle characteristics. The calculated gravimetric hydrogen storage capacities indicate that K2LiGaH6 has the highest capacity at 3.22 wt%, followed by K2LiInH6 (2.60 wt%), Rb2LiGaH6 (2.16 wt%), K2LiTlH6 (1.88 wt%), and Rb2LiInH6 (1.86 wt%), with Rb2LiTlH6 having the lowest value at 1.46 wt%. A decrease in storage capacity is observed when the cationic atom at the Q and M site in Q2LiMH6 is replaced, due to differences in atomic radius. Overall, the findings of this study identify Q2LiMH6 (Q =K, Rb; M =Ga, In, Tl) as a viable candidate for next- generation hydrogen storage owing to its optimal gravimetric capacity and excellent stability.

Title

Surfaces and Interfaces

Publisher

ELSEVIER

Publisher Country

Netherlands

Indexing

Thomson Reuters

Impact Factor

5.7

Publication Type

Both (Printed and Online)

Volume

67

Year

2025

Pages

11