Achieving Ambient‐Temperature Fast Hydrogenation Properties in Ga‐Doped Mg–Ni Alloy: Dual‐Phase Synergistic Catalysis and Stacking Fault Channels

ABSTRACT The high operating temperatures and sluggish kinetics of Mg‐based hydrogen storage materials (HSMs) are urgently being addressed. In this work, a novel Mg–Ni–Ga HSM with dual‐phase synergistic catalysis is developed, including the fishbone‐like Mg 3 Ni 2 Ga 1 catalytic phase and the Mg 2 Ni phase with stacking faults (SFs). The spheroidization of Mg grains is inhibited by the pinning effect of the Mg 3 Ni 2 Ga 1 phase, and the high‐energy Mg grain boundaries are obtained. High‐density SFs are induced in the Mg 2 Ni phase via Ga dissolution. It is worth noting that Mg 94.5 Ni 5 Ga 0.5 alloy absorbs 0.37 wt% H 2 merely at 25°C, and absorbs 2.71 wt% H 2 at 150°C under even 0.1 MPa. The dehydrogenation activation energy is significantly decreased from 81.86 kJ mol −1 in Mg 95 Ni 5 alloy to 67.68 kJ mol −1 . The room temperature and low‐pressure hydrogenation performance are achieved through these multiphase synergistic catalysis: H 2 molecule dissociation facilitated by the Mg 3 Ni 2 Ga 1 phase, hydride nucleation promoted by high‐energy Mg grain boundaries, additional rapid diffusion channels for H atoms, and the enhanced “hydrogen pump” effect provided by the Mg 2 Ni phase with SFs structure.