Superior Hydrogenation Performance of Mg-Ni-Y Alloys at a Moderate Temperature with Lanthanum-Functionalized MXene-Derived Catalysts

The practical deployment of magnesium-based alloys, despite their attractive hydrogen-storage capacity and economical advantage, faces critical barriers in the form of high dehydrogenation temperatures and inadequate sorption kinetics. To overcome these barriers, a two-dimensional layered La x @Ti 3 C 2 -derived catalyst was therefore developed, which exhibits high catalytic activity toward the Mg-4Ni-2Y alloy. The Mg-4Ni-2Y + 10 wt % La 0.2 @Ti 3 C 2 composite not only lowered the onset absorption/desorption temperatures to 23.3 °C and 265.5 °C but also enabled the composite to achieve superior sorption kinetics, absorbing 4.80 wt % H 2 in 1 min at 150 °C and releasing 5.16 wt % H 2 in 4 min at 350 °C. Furthermore, the apparent activation energy (E a ) was substantially reduced to 85.22 ± 2.38 kJ/mol for the composite, thereby decreasing the dehydrogenation temperature and accelerating the kinetics. Systematic analysis suggests that the catalytic enhancement is primarily associated with highly dispersed Ti 0 species, which are proposed to act as the primary active sites for hydrogen dissociation and recombination. La decoration is suggested to serve as an electronic promoter, modulating the electronic structure of Ti sites and stabilizing the interfacial environment. This synergistic Ti-La interaction facilitates hydrogen activation and interfacial transfer without altering the intrinsic Mg/MgH 2 thermodynamics, thereby significantly accelerating hydrogen sorption kinetics.