Exploring the Hydrogen Storage Performance of MgH₂ Catalyzed by Two Transition Metals Ni and Co by In‐situ Calorimetry and Density Functional Theory Calculations

Abstract

Addressing the drawbacks of magnesium‐based hydrogen storage materials with high thermal stability and slow kinetics of hydrogen absorption and discharge remains a current research challenge. In this paper, MgH2 catalyzed by Ni and Co has been prepared by ball milling. The hydrogen storage performance of the 90MgH2+5Ni+5Co composite has been investigated using common techniques, such as differential scanning calorimetry (DSC) and pressure‐composition‐isothermal (PCI) method. Furthermore, the main focus of the study was to investigate the changes in dehydrogenation enthalpy of MgH2 upon addition of Ni and Co, and the bonding mode during the dehydrogenation process of MgH2 and the dissociation energy barrier of hydrogen molecules on the surface of Mg were calculated using density functional theory. The results showed that the dehydrogenation activation energy of 90MgH2+5Ni+5Co decreased by 55.9 kJ/mol compared with that of MgH2. The dehydrogenation enthalpies of as‐milled MgH2 and 90MgH2+5Ni+5Co were 64.8 kJ/mol H2 and 63.4 kJ/mol H2, respectively. Thus the co‐doping of Ni and Co contributed significantly to decrease the thermodynamic stability and improve the hydrogen sorption kinetic properties of MgH2.