Structural, electronic, thermoelectric, thermodynamic, and elastic properties of XPH2 (X = Li, Na, K) for hydrogen storage application: A first principle study

Abstract

H2 storage is the current research focus for scientists of this era as it is naturally occurring, non-polluting, economical, and clean. This manuscript is based on a first-principles study of metal hydrides and the WIEN2k code is used to determine their H2 storage properties. The investigation of the present work discloses the elastic, structural, electronic, thermoelectrical, and thermodynamic properties of XPH2 (X = Li, Na, K) metal hydrides with the help of density functional theory (DFT). All of these compounds are tetragonal and their gravimetric densities are 5.048, 3.6011and 2.796 wt% for LiPH2, NaPH2, and KPH2, respectively. The PDOS, TDOS, and band structure (by mBJ) of the XPH2 hydrides are determined by their electronic characteristics, and the findings demonstrate that these metal hydridesare metals. The GIBBS2 code is also used to evaluatethermodynamic properties like entropy,Debye temperature, and specific heat. The elastic constant is used to identify the mechanical stabilities of these hydrides, demonstrating that these compounds have a ductile nature and are mechanically stable except for LiPH2. The formation energy of these compounds is calculated. Furthermore, the Boltzmann transport equation is also used for the elucidation of thermoelectric properties.