AlV₃/Cu₉Al₄ Composite Derived from Al-V-Cu Precursors for Enhancing the Hydrogen Storage Properties of MgH₂

Developing catalysts is an important way to modify the hydrogen storage performances of magnesium hydride (MgH₂). The hydrogen storage performance of MgH₂ was enhanced by employing a mixture of AlV₃/Cu₉Al₄ alloy as a catalytic additive, which was fabricated via arc melting followed by hydrogen plasma treatment. The as-prepared AlV₃/Cu₉Al₄ was mechanically added into MgH₂ through ball milling to form MgH₂-x wt % AlV₃/Cu₉Al₄ composites (x = 2.5, 5, 7.5). Remarkably, the MgH₂-5 wt % AlV₃/Cu₉Al₄ composite demonstrated the best performance: desorbing 6.7 wt % hydrogen within 1 h at 598 K, which is 1.9 times faster than pristine MgH₂ 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 AlV₃/Cu₉Al₄ particles, which effectively suppresses the coarsening and agglomeration of Mg/MgH₂ 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.