Modulating the hydrogen storage, mechanical, thermodynamic, structural and optoelectronic characteristics in cesium-based double perovskites through structural vacancy

Defected hydrides are crucial to investigate for hydrogen storage purposes because they possess a higher tendency to improve hydrogen absorption and desorption by introducing active defect sites, which helps in decreasing activation energies and enhancing kinetics. In this paper, we have analyzed the effects of the physical traits of Cs 2 AlInH 6 by creating a vacancy at the cation site. The analysis of the structural integrity revealed that Cs 2 AlInH 6 possesses higher stability than Cs 2 InH 6 . The computed formation energies indicate that both hydrides are thermodynamically stable. The mechanical properties for both hydrides are computed via Thomas Charpin’s approach. The Debye and melting temperature signify that Cs 2 AlInH 6 possesses stronger atomic interactions and higher endurance to external heat as compared to Cs 2 InH 6 . An indirect bandgap of 1.64[Formula: see text]eV is reported for Cs 2 AlInH 6 , and Cs 2 InH 6 demonstrates metallic characteristics as evaluated by the electronic properties. A higher level of electronic interactions in the visible region is reported for Cs 2 AlInH 6 , whereas for Cs 2 InH 6 , high polarization is noticed in the infrared region, which is described via the optical analysis. The hydrogen storage properties reveal that the removal of the Al atom has significantly enhanced the gravimetric and volumetric densities, while lowering the desorption temperature of the material, making it more efficient and practical for hydrogen storage and renewable energy applications.