Comparative study of hydrogen storage potential in sodium-based ternary hydrides: NaXH3 (X = B, Si, Ge)

H-rich hydrides' high gravimetric capacity and tunable thermodynamic behaviour make them intriguing. The structural, mechanical, electrical, and thermodynamic properties of NaXH 3 (X = B, Si, Ge) hydrides are studied using first-principles plane-wave pseudopotential calculations. Exchange-correlation effects were treated using the PBEsol generalised gradient approximation. The strain-stress method was used to determine elastic moduli, while the Debye model was used to evaluate thermodynamic properties. Due to its higher Young's modulus and shear modulus, NaBH 3 exhibits the most significant mechanical stiffness, whereas NaGeH 3 shows the lowest resistance to deformation. NaBH 3 also displays the lowest entropy and heat capacity over the temperature range, indicating superior thermal stability and stronger hydrogen-lattice interactions. Hydrogen storage performance decreases from NaBH 3 to NaSiH 3 , then to NaGeH 3 . This comparative analysis reveals that the core atom X influences the stability of NaXH 3 hydrides and their hydrogen storage potential.