Synergistic dual-modification regulation of dehydrogenation kinetics of MgH2 by MOF-derived Core-shell Ni&C

In this study, a Ni–C co-dispersed catalyst (denoted as Ni&C) with a uniform spherical morphology (≈2 μm diameter) and Core-shell structure was synthesized using Ni-based metal-organic framework (MOFs) as precursors. The Core-shell Ni&C catalyst significantly improved the dehydrogenation kinetics of MgH 2 . The MgH 2 –Ni&C composite exhibited a remarkably low onset dehydrogenation temperature of 192.6 °C, which is 136.9 °C lower than that of pure MgH 2 . The peak dehydrogenation temperature and dehydrogenation temperature span were reduced by 120 °C and 31.3 °C, respectively. At 300 °C, the composite released 5.82 wt% H 2 within 2.1 min. The apparent activation energy for dehydrogenation decreased to 76.78 kJ mol −1 , far below that of pure MgH 2 (138.18 kJ mol −1 ). Mechanistic analysis revealed that Mg 2 NiH 4 /Mg 2 Ni phases formed in-situ during hydrogen cycling acted as "hydrogen pumps" and nucleation promoters of matrix, while the carbon provided good spatial confinement and enhanced thermal conductivity . Moderate coupling between Ni and C generated synergistic effects , collectively optimizing the dehydrogenation performance.