Improved thermodynamic properties of (Sc, V, Ti, Fe, Mn, Co, and Ni) doped NaBH4 for hydrogen storage: First-principal calculation

Abstract

Sodium borohydride (NaBH4) shows promise as a hydrogen storage option, but its substantial thermodynamic stability limits its practical application. Enhancing NaBH4 by introducing transition metals is an effective approach to enhance its hydrogen-related characteristics. Nevertheless, even with the most successful additives, the temperatures needed for hydrogen release remain too elevated, exceeding 400 °C, which hinders its practical utility. Using first-principles density functional, we have investigated the potential of sodium borohydride as a hydrogen-based fuel source. Our focus has been on the stable α-phase NaBH4 structure with space group symmetry F-43m (216), aiming to understand the impact of 3d transition metal (Sc, V, Ti, Fe, Mn, Co, and Ni) doping on the structural, electronic, and dehydrogenation properties of the NaBH4 system. Furthermore, the heat of formation and desorption temperature values obtained align with the stability and volumetric capacity criteria set by the U.S. Department of Energy (DOE). Our findings indicate that doping transition metals at the Na site weakens the B–H bonds, thereby enhancing the dehydrogenation performance. Among the various systems studied, those doped with Sc and Ti exhibit the most favorable dehydrogenation properties.