First-principles to explore the hydrogen storage properties of XPtH3 (X=Li, Na, K, Rb) perovskite type hydrides.

Based on the first-principles, the hydrogen storage, mechanical, electronic, optical, thermodynamic and kinetic properties of XPtH 3 (X = Li, Na, K, Rb) perovskites are investigated for the first time in this work. The lattice constants of the optimized LiPtH 3 , NaPtH 3 , KPtH 3 , and RbPtH 3 are 3.54, 3.63, 3.80, and 3.90 Å, respectively. The Cauchy's pressure and the ratio of the bulk modulus to shear modulus (B/G) consistently prove that the XPtH 3 hydrides all exhibit ductility. The investigation of electronic properties reveals that XPtH 3 compounds exhibit metallic nature. According to Poisson's ratio and charge density distribution, the bonding type of XPtH 3 hydrides is mainly ionic. The Bader partial net charges are also calculated to analyze the charge transfer in XPtH 3 perovskites. The results of the optical properties of XPtH 3 compounds reveal that they are high dielectric constant and high refractive index materials. It is found that the XPtH 3 perovskites exhibit thermodynamic, mechanical, and dynamic stability. The gravimetric hydrogen storage capacities are 1.45, 1.35, 1.26, and 1.06 wt% for LiPtH 3 , NaPtH 3 , KPtH 3 , and RbPtH 3 , respectively. The hydrogen desorption temperatures of LiPtH 3 , NaPtH 3 , KPtH 3 and RbPtH 3 are 237.77, 225.39, 162.43, and 80.11 K, respectively. Our results suggest that LiPtH 3 hydride is the most suitable material for hydrogen storage applications among the four compounds. Systematic calculation of the physical and hydrogen storage properties of XPtH 3 (X = Li, Na, K, Rb) for the first time. Moreover, XPtH 3 (X = Li, Na, K, Rb) hydrides are thermodynamically, mechanically, and dynamically stable. Our results provide new candidates for hydrogen storage materials. [Display omitted] • XPtH 3 (X = Li, Na, K, Rb) perovskites have been investigated using first-principles. • XPtH 3 compounds exhibit thermodynamic, mechanical, and dynamical stability. • The gravimetric hydrogen storage capacity is found to be 1.45 wt% for LiPtH 3. [ABSTRACT FROM AUTHOR]