First principle investigation on the physical properties of rhodium-based XRhH3 (X= Na, Cs or Sr) perovskites hydride for hydrogen storage applications
Umair Azhar, Muhammad Talha Iftikhar, Muhammad Arif, Muhammad Awais Rehman, Taleb Ibrahim, Oussama M. El‐Kadri
Abstract
Much research has been done on perovskite hydride materials to uplift the field of solid-state hydrogen storage . However, it is challenging to design materials that at the same time demonstrate good modulus properties with improved ductility, anisotropic nature, and thermal stability. Herein, by the inherent properties of high melting temperature, corrosion resistance , catalytic performance, and comparatively large atomic radius of rhodium (Rh), we have conducted a comprehensive investigation into the optical, structural, electronic, mechanical, thermodynamic, and hydrogen storage properties of the novel XRhH 3 (X: Na, Cs and Sr) perovskite-type hydrides by using density functional theory (DFT). Based on their elastic characteristics upon fulfillment of Born stability criteria and negative formation energies, these materials are thermodynamically and mechanically stable. The X-ray diffraction patterns and structural properties show that the current materials have a polycrystalline cubic phase, as the CsRhH 3 material occupies more volume owing to its higher lattice constants than those of NaRhH 3 and SrRhH 3 . On the other hand, NaRhH 3 shows a greater bulk, shear, and Young's modulus , hence stronger than CsRhH 3 and SrRhH 3 . The Poisson's ratio , Pugh's ratio (B/G), and Cauchy pressure ( Cp ) reveal the ductile behavior of the compounds along with Debye temperature (202 k – 366 k), which are desirable for hydrogen storage materials . The calculated hydrogen storage capacities are 2.3 wt%, 1.26 wt %, and 1.55 wt % for XRhH 3 (X = Na, Cs , and Sr), respectively. To the best of our knowledge, this study represents the first investigation of XRhH 3 compounds and offers a great potential for hydrogen storage applications and devices.