First-principles calculations on structural, mechanical and thermodynamic properties of orthorhombic Mg2BeTMH8 (TM=Ni, Cu and zn) for hydrogen storage applications.

Effective hydrogen storage is a crucial requirement for harnessing hydrogen as an energy source. Among various storage methods, solid-state hydrogen storage holds promise but necessitates extensive investigation. This study employs density functional theory within the WIEN2k code to improve the desorption temperature and kinetic properties of MgH 2 by introducing Be in combination with transition elements (Ni, Cu, and Zn). The gravimetric hydrogen storage capacity for all studied compounds exceeds 6%. Introduction of different transition elements with Be leads to improvements in formation and cohesive energies, as well as in desorption temperature. Mechanical stability, determined through elastic constants, is confirmed for all hydrides meeting the Born stability criteria. Detailed analyses encompass bonding characteristics, shear modulus, bulk modulus, Cauchy pressures, elastic anisotropy, and Vickers Hardness tests. Electronic properties reveal that Mg 2 BeZnH 8 exhibits the semiconductor nature, and properties are further improved by using TB-mBJ approach. Electronic charge density calculations unveil interatomic bonding nature. Numerous previously unexplored thermodynamic aspects of these hydrides have been investigated and are now presented. • Orthorhombic Mg 2 BeTMH 8 (TM = Ni, Cu and Zn) have been investigated by using density functional theory. • The gravimetric hydrogen storage capacity for all compounds studied exceeds 6%. • Mg 2 BeZnH 8 has low desorption temperature than other two studied hydrides. • All the studied materials are mechanically stable and hard. • Electronic properties reveal that these hydrides exhibit semiconductor nature, except Mg 2 BeNiH 8. [ABSTRACT FROM AUTHOR]