Synergistic catalytic effect of (La, Sm)2O3@C on the hydrogen storage kinetics of Mg-Ce-Ni alloy

Poor hydrogen absorption/desorption kinetics and high thermodynamic stability remain key barriers to the practical use of Mg-based hydrogen storage materials. In this work, a (La, Sm) 2 O 3 @C composite catalyst was prepared by a chemical blowing method and incorporated into Mg 96 Ce 3 Ni alloy via high-energy ball milling at doping levels of 1–7 wt.%. Under comparable conditions (573 K, 3.0 MPa H 2 ), increasing the catalyst content from 1 wt% to 7 wt% lowered the apparent dehydrogenation activation energy from 107.41 kJ mol −1 to 79.20 kJ mol −1 . At 573 K the hydrogen-absorption saturation of LS7 reached 76.8%, and the time required to release 5 wt% H 2 was halved from 30 min to 15 min. Van ’t Hoff analysis showed that the reaction enthalpy remained essentially unchanged (∼76 kJ mol −1 ) indicating that the catalyst improves kinetics without significantly altering thermodynamic stability. The observed performance gains are therefore attributed primarily to microstructural refinement and an increased density of catalytic sites.