Investigations for hydrogen storage applications of XPtH3 (X = Cs, Fr) hydrides: A first principles study

Abstract

In this work, the first principles calculations are performed to study the elasto-mechanical, electronic, thermodynamic and hydrogen storage properties of metal hydrides XPtH₃ (X = Cs, Fr). The optimized lattice constant of CsPtH₃ (4.004 Å) is slightly smaller than that of FrPtH₃ (4.016 Å). The gravimetric hydrogen storage capacity, $C$ _wt%, for CsPtH₃ and FrPtH₃ is 0.91% and 0.71%, respectively. The calculated elastic constants, bulk modulus, shear modulus and Young’s modulus indicate that CsPtH₃ is more harder, stronger and stiffer than FrPtH₃. The Cauchy pressure and shear constant confirmed the covalent bonding nature and mechanical stability of XPtH₃ (X = Cs, Fr). The band structures and density of states unveiled the metallic nature of both hydrides. Different thermodynamic parameters are investigated under pressure and temperature variation. FrPtH₃ showed greater gravimetric hydrogen storage capacity and superior mechanical properties anticipating it is potential for hydrogen storage applications.