Cr2O3-Induced Magnetic-Gradient-Field Engineering for Accelerated Hydrogen Transport in Magnesium Hydride

Magnesium hydride (MgH 2 ) is regarded as a highly promising hydrogen carrier for hydrogen‐energy infrastructure; however, the intrinsically strong Mg-H bonding severely limits its hydrogen release and uptake under mild operating temperatures. In this work, amorphous Ni 0.9 Fe 0.1 -Cr 2 O 3 nanoparticles were synthesized by a one-step co-reduction and integrated with MgH 2 by ball milling to accelerate reversible solid-state hydrogen storage. Cr 2 O 3 suppresses long-range ordering of NiFe, yielding nano amorphous catalysts well anchored on MgH 2 . DFT reveals that Cr 2 O 3 disrupts Ni–Fe exchange and induces a Ni magnetic-moment gradient, which guides H migration and, together with band-overlap-enabled charge transfer, which collectively promote H diffusion and Mg-H bond cleavage. Therefore, temperature-programmed desorption shows the composite starts releasing H 2 at 206 °C (about 130 °C lower than pristine MgH 2 ), and delivers 3.56 wt% within 60 min at 235 °C. Overall, these findings establish magnetic-gradient-field regulation as a viable catalyst-design principle for high-performance MgH 2 -based solid-state hydrogen storage.