AlV ₃ /Cu ₉ Al ₄ Composite Derived from Al–V–Cu Precursors for Enhancing the Hydrogen Storage Properties of MgH ₂

Developing catalysts is an important way to modify the hydrogen storage performances of magnesium hydride (MgH 2 ). The hydrogen storage performance of MgH 2 was enhanced by employing a mixture of AlV 3 /Cu 9 Al 4 alloy as a catalytic additive, which was fabricated via arc melting followed by hydrogen plasma treatment. The as-prepared AlV 3 /Cu 9 Al 4 was mechanically added into MgH 2 through ball milling to form MgH 2 - x wt % AlV 3 /Cu 9 Al 4 composites ( x = 2.5, 5, 7.5). Remarkably, the MgH 2 -5 wt % AlV 3 /Cu 9 Al 4 composite demonstrated the best performance: desorbing 6.7 wt % hydrogen within 1 h at 598 K, which is 1.9 times faster than pristine MgH 2 under same conditions. Based on kinetic analyses, the activation energy for hydrogen absorption decreased notably to 74.91 kJ/mol, while that for desorption dropped to 150.50 kJ/mol. Furthermore, the composite exhibited exceptional cycling stability, retaining 99% of its initial hydrogen absorption and desorption capacity after 20 cycles. This outstanding reversibility is attributed to the stable dispersion of AlV 3 /Cu 9 Al 4 particles, which effectively suppresses the coarsening and agglomeration of Mg/MgH 2 particles. This work offers a feasible approach for designing transition metal alloy catalysts to address the kinetic constraints of metal hydride-based hydrogen storage systems.