Investigation of the hydrogen storage potential of certain perovskite – type hydrides via density functional theory

The increase in global energy demand and the environmental impacts of fossil fuels have stimulated interest in hydrogen as a renewable, sustainable, and clean energy carrier. However, the primary obstacle to the practical realization of hydrogen energy potential is the challenge of its safe and high-density storage. In this thesis, the physical properties and gravimetric hydrogen storage performances of perovskite – type oxide (ABO3) (A = K, Rb, Cs; B = Al, Sb, Si, Sn), their respective hydride (ABH3) and oxide – hydride (ABO3Hx; x = 3, 6, 8) derivatives, and double perovskite – type hydride (M2NH6) (M = Mg, Ca, Sr, Ba; N = Co, Ni) crystal systems, which demonstrate potential as solid – state hydrogen storage environment, were evaluated using the VASP based on Density Functional Theory (DFT) principles and utilizes a plane – wave basis set. In the analyses, the Projector Augmented Wave (PAW) method was utilized for electron - ion interactions, while the exchange – correlation energy was represented by the GGA – based PBE functional. The thermodynamic stabilities of the calculated systems were assessed through formation enthalpies, whereas mechanical and lattice dynamical stabilities were determined by examining elastic constants and phonon dispersion curves, respectively.The results revealed that ABO3 structures provide a robust host framework for hydrogen due to their high mechanical stability, and that the incorporation of high concentrations of hydrogen into the structure can modify the electronic structure. In ABH3 and M2NH6 systems, it was determined that Density of States (DOS) and net charge analyses that the bonding character of hydrogen is a determinant factor for the desorption temperature. Consequently, the gravimetric hydrogen storage performances and stability limits of the investigated structures were theoretically evaluated, identifying these systems as remarkable candidates for hydrogen storage applications.