First-principles screening of the physical and hydrogen storage properties of Rh-based perovskites XRhH<sub>3</sub> (X = Ca, Ba) for hydrogen storage applications
Jinhua Zhou, Shijie Zhang, Ruijie Song, Shanjun Chen, Yan Chen, Jie Hou
Abstract
Abstract In this work, we conduct a comprehensive research of XRhH 3 (X = Ca, Ba) hydrides using first-principles calculations, including their crystal structure, photoelectric, mechanical, dynamic, thermodynamic and hydrogen storage properties. Based on the Pugh’s ratio (B/G) along with Poisson’s ratio, it is concluded that XRhH 3 (X = Ca, Ba) hydrides are both ductile ionic compounds. As evidenced by electronic property studies, these materials demonstrate metallic traits. Evaluating the formation energy and adherence to the Born stability criterion confirms that CaRhH 3 and BaRhH 3 possess both mechanical and thermodynamic stability. Analysis of the phonon dispersion curves reveals that they are both kinetically stable as well. The optical properties of XRhH 3 (X = Ca, Ba) compounds demonstrate notably high polarizability and reflectivity. Our calculations indicate that the gravimetric hydrogen storage capacities of 2.07 wt% for CaRhH 3 and 1.24 wt% for BaRhH 3 , respectively, with the corresponding dehydrogen temperatures of 350.3 K and 246.2 K, respectively. Hydrogen ion migration barriers for CaRhH 3 and BaRhH 3 are 0.80 and 0.80 eV, revealing the efficient diffusion. These findings suggest that CaRhH 3 exhibits more favorable hydrogen storage potential than BaRhH 3 . Our study significantly deepens the understanding of perovskite hydrides’ physical properties, and lays crucial theoretical groundwork and novel perspectives for designing high-performance hydrogen storage materials.