In-Situ Formation of V and Mg2co/Mg2coh5 for Boosting the Hydrogen Storage Properties of Mgh2

Abstract

Among the potential candidates for solid-state hydrogen storage, magnesium hydride (MgH2) exhibits high storage capacity of 7.6%. However, its commercial application is hindered by the unsatisfactory kinetics properties and stable thermodynamics. In this study, we synthesized porous spherical CoV2O6 and incorporated it into MgH2. The incorporation of 9 wt% CoV2O6 significantly improved the dehydrogenation kinetic of MgH2, reducing the initial dehydrogenation temperature of MgH2 to 190 °C. Additionally, rapid hydrogen uptake was also observed, approaching 6.5 wt% H2 within 1000 s at 190 °C. A notable decrease of 45.78 kJ/mol in the apparent activation energy (Ea) for dehydrogenation signifies an improved dehydrogenation kinetic. The formation of Mg2Co/Mg2CoH5, along with the presence of single-valence and multi-valence vanadium, facilitated multiple electron transfer pathways. In particular, vanadium elongated the Mg–H bond is responsible for the high catalytic activity in boosting the hydrogen storage performance of MgH2. These findings provide new intuitions for further research to enhance the kinetic properties of hydrogen adsorption and desorption in magnesium hydride.

Keywords: MgH2, Hydrogen Storage, porous spherical CoV2O6, Catalytic mechanism