Investigating storage capacity in optically active perovskite type hydrides XCaH3 (X: Na, Li and Cs) for sustainable hydrogen storage application

Abstract

The development of hydrogen storage materials is essential for advancing clean energy technologies, particularly in the context of hydrogen fuel cells and renewable energy storage systems. Perovskite hydride materials have garnered considerable interest in light of their unique crystal structure and potential for efficient hydrogen storage. This study investigates the structural, mechanical, electro-optical, and hydrogen storage properties of optically active perovskite hydrides XCaH₃ (X: Na, Li, Cs) by applying first principle calculations with aiming to characterize these materials for optically mechanized hydrogen storage system. Formation energy and elastic constants verify that XCaH₃ materials are thermodynamically and mechanically stable. Calculated B/G ratio and Cauchy pressure values indicate that NaCaH₃ is ductile while LiCaH₃ and CsCaH₃ are brittle. A comparison has been made between the bulk modulus, derivatives, and lattice parameters with the existing published data. Based on the electronic properties of these compounds, they were found to be semiconductors. Analyzing the optical properties of these hydrides has demonstrated that they exhibit high absorption rates in the ultraviolet region. Furthermore, calculated gravimetric hydrogen capacity of NaCaH₃, LiCaH₃, and CsCaH₃ is found to be 4.38 wt%, 5.7 wt%, and 1.691 wt% relative to the 4.5 wt% target set by the US Department of Energy. This is an enhanced effort to explore XCaH₃ perovskite hydrides to provide a new direction to hydrogen storage systems.