Enhanced hydrogen storage performance of MgH2 using Ni and CeO2 catalysts

Ni/CeO 2 @C catalyst with abundant oxygen vacancies was prepared. • The MgH 2 + 4 wt% Ni/Ceo 2 @C composite releases 6 wt% H 2 in 50 min at 613 K. • Activation energy: 95.77 kJ/mol; Peak dehydrogenation: 593 K. • Performance enhanced by synergistic Ni/CeO 2 /C roles. A carbon-supported nickel/cerium dioxide composite catalyst (Ni/CeO 2 @C) was synthesized through a hydrothermal–calcination route and introduced into magnesium hydride (MgH 2 ) at loadings of 2, 4, 6, and 8 wt%. The phase composition and microstructure of the catalyst and MgH 2 -based composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM), while their hydrogen absorption–desorption behavior was evaluated at 553–613 K. Among the investigated compositions, MgH 2 + 4 wt% Ni/CeO 2 @C exhibited the most favorable overall balance of reversible hydrogen capacity, sorption kinetics, apparent thermodynamic parameters, and particle dispersion. At 613 K, the composite achieved hydrogen absorption and desorption capacities of 6.45 and 6.16 wt%, respectively, and released nearly 6.0 wt% H 2 within 50 min. At 573 K, it absorbed 5.81 wt% H 2 and released approximately 5.4 wt% H 2 within 100 min. The apparent dehydrogenation activation energy was 85.96 kJ mol −1 . Van't Hoff analysis yielded apparent absorption and desorption enthalpy changes of −81.32 and + 83.38 kJ mol −1 H 2 , respectively. After 20 consecutive absorption–desorption cycles, the composite retained approximately 94.04% of its absorption capacity and 95.41% of its desorption capacity. These results indicate that a 4 wt% Ni/CeO 2 @C loading provides a favorable combination of hydrogen-storage capacity, kinetic performance, apparent thermodynamic behavior, and preliminary cycling reversibility under the investigated conditions.