Enhancing the gravimetric hydrogen storage capacity and optoelectronic performance of a novel Li2GePbH6 hydride perovskite: a DFT investigation

Abstract

An inorganic metal hydride cubic perovskite, Li₂GePbH₆, shows significant promise for useful hydrogen (H₂) storage applications. A detailed exploration of its physical properties was conducted using the first principles Density Functional Theory (DFT) computations. These investigations confirmed its stability through several criteria, including negative formation energies (0.735 eV per atom), elastic constants, phonon dispersion spectra, and tolerance factor (0.91), indicating thermodynamic, mechanical, dynamic, and structural stability in the cubic phase. Electronic structure analysis revealed metallic behavior for Li₂GePbH₆. Optical property assessments demonstrated strong interactions with electromagnetic radiation, suggesting potential for optoelectronic applications. Additionally, this material exhibits high stiffness, hardness, mechanical strength, and anisotropic behavior, making it suitable for long-term engineering use. Thermodynamic evaluation confirmed its stability across a broad temperature range. Notably, Li₂GePbH₆ attained 2.02 wt% gravimetric hydrogen storage capacity. Its H₂ release temperature was found to be 542.6 K, positioning it as viable candidate for solid-state hydrogen storage technologies.