Enhanced hydrogen sorption kinetics of MgH2 enabled by a CeO2-Nb2O5-Ni multicomponent catalyst

Ni-loaded Ce/Nb oxide catalysts (CeNb-x%Ni) were prepared and ball-milled with MgH 2 under H 2 to investigate the effects of Ni loading on sorption kinetics. The results reveal that the 40%Ni catalyst featured the most balanced behavior. MgH 2 -10%(CeNb-40%Ni) absorbed 5.516 wt% H 2 within 1 min at 350 °C and released approximately 5.6 wt% H 2 within 30 min after hydrogenation. At 150 °C, it still absorbed 3.54 wt% H 2 in 6.5 min and reached 4.921 wt% after 30 min. TPD and DSC curves suggest that the onset and main release temperatures moved to lower values, while kinetic analysis presented a much smaller apparent dehydrogenation barrier. XPS indicates the presence of Mg-H-related species, metallic/interfacial and oxidized Ni species, Ce 3 + /Ce 4+ surface states, and Nb 5+ /Nb δ⁺ -related components. These surface states, together with the refined particles and crack/pore-rich surface produced during milling and cycling, may facilitate hydrogen transfer across the MgH 2 /catalyst interface. Thus, an appropriate Ni amount in a Ce/Nb oxide matrix is important for accelerating MgH 2 absorption and desorption.