Effect of UiO-66 NH2 on hydrogen storage performance of MgH2

In this study, UiO-66-NH 2 , known for its excellent thermal stability, was incorporated into MgH 2 for the first time, demonstrating strong catalytic activity in enhancing the hydrogen storage performance of MgH 2 . The effects of varying UiO-66-NH 2 loadings (5, 10, 15, and 20 wt%) on the hydrogen storage behavior of MgH 2 were systematically examined using a ball milling process. The introduction of UiO-66-NH 2 significantly lowered the onset desorption temperature from 350 °C (for milled MgH 2 ) to 280 °C. The composite exhibited markedly improved kinetics, achieving rapid hydrogen absorption of approximately 6.2 wt% within 2 min at 250 °C under 33.0 atm H 2 pressure, and desorption of about 5.9 wt% within 2 min. The apparent activation energy for dehydrogenation decreased to 89.17 ± 3.2 kJ/mol H 2 , compared to 132 ± 8.7 kJ/mol H 2 for pure MgH 2 . The MgH 2 /UiO-66-NH 2 composite maintained excellent cyclic stability over 20 cycles, with only a minor capacity loss of about 0.002 wt%. Comprehensive characterization using XRD, TEM, and SEM confirmed the structural and morphological changes, and a plausible catalytic mechanism of UiO-66-NH 2 on MgH 2 was proposed based on these findings. • UiO-66-NH 2 MOF can effectively improve the hydrogen storage property of MgH 2 . • MgH 2 /5 wt%UiO-66-NH 2 starts to release hydrogen at 280 °C. • MgH 2 /5 wt%UiO-66-NH 2 can release 6.0 wt% of H 2 at 300 °C within 10 min. • The desorption E A of MgH 2 /5 wt%UiO-66-NH 2 is reduced to 89.17 kJ/mol.