Ge-based hydride-perovskites for hydrogen storage application: A first-principles study

초록

The increasing demand of clean sources of energy has invited a lot of interest in hydrogen as an alternative source of fuel and effective hydrogen storage remains rather challenging, however. This study explores the potential of Ge-based hydride perovskites i.e., LiGeH3 and NaGeH3, as viable candidates for hydrogen storage material. By using first-principles calculations, we determined the lattice parameters of LiGeH3 and NaGeH3 as 3.93 & Aring; and 4.05 & Aring;, respectively. The investigated lattice constant resemble well with the previously investigated similar materials. The stability of these materials is investigated with the help of formation energy, phonon dispersion curves and ab-initio molecular dynamics simulations. The band structure and density of states show metallic behavior in both materials. The optical properties like reflectivity, absorption coefficient, refractive index, dielectric function, conductivity and loss function are also investigated in detail. The mechanical stability is estimated using Born stability criteria. The anisotropic factor, Bulk modulus, Shear modulus, Young's modulus, Poisson's ratio, Pugh's ratio, and Cauchy pressure are also determined using the elastic constant to predict the mechanical behavior of these materials. The gravimetric hydrogen storage capacity of LiGeH3 and NaGeH3 is found to be 3.66% and 3.07% respectively. LiGeH3 has a slightly higher capacity owing to its lighter atomic mass than sodium indicating that both materials have potential of storing hydrogen.

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