In the present work, highly effective Ni-MnO binary nanocomposite catalysts were designed and synthesized using a one-pot method from Ni-Mn based bi-metal organic frameworks (MOFs). These nanocomposites were introduced into MgH₂ through ball milling as catalysts to enhance the hydrogen storage properties of MgH₂. Through varying the Ni/Mn ratio in the bimetal MOFs, it is found that the Ni₁Mn₁₋MOF derived catalyst showed the best promotion effect on MgH₂. The MgH₂–10 wt.% Ni₁Mn₁₋MOF derivative demonstrated favorable overall performance with the low desorption peak temperature (218.2 °C) with a saturated hydrogen capacity of 6.42 wt.% and rapid hydrogen release/uptake kinetics. It can still reabsorb about 1.15 wt.% H₂ within 30 min at a temperature as low as 50 °C. Both performance tests (DSC and TPD) and structural characterizations (XRD, HRTEM, etc.) revealed that the synergistic role of in situ formed Mg₆MnO₈ and Mg₂NiH₄/Mg₂Ni phases for improving the hydrogen sorption properties of MgH₂. Theoretical calculations reveal that Mg₆MnO₈ destabilizes metal-H bonds in MgH₂ and Mg₂NiH₄, leading to an enhanced “hydrogen pump” effect of Mg₂NiH₄ for MgH₂. This research provides a strategy to rational design and preparation of bimetal MOF derivatives for the development of advanced hydrogen storage materials.

Achieving dual regulation of the kinetics and thermodynamics of MgH₂ is essential for the practical applications. In this study, a novel nanocomposite (In@Ti-MX) architected from single-/few-layered Ti₃C₂ MXenes and ultradispersed indium nanoparticles was prepared by a bottom-up self-assembly strategy and introduced into MgH₂ to solve the above-mentioned problems. The MgH₂+In@Ti-MX composites demonstrate excellent hydrogen storage performance: The resultant In@Ti-MX demonstrated a positive effect on the hydrogen storage performance of MgH₂/Mg: the dehydrogenated rate of MgH₂+15 wt%In@Ti-MX reached the maximum at 330 ℃, which was 47 ℃ lower than that of commercial MgH₂; The hydrogenation enthalpy of the dehydrided MgH₂+15 wt%In@Ti-MX and MgH₂+25 wt%In@Ti-MX were determined to be −66.2 ± 1.1 and −61.7 ± 1.4 kJ·mol⁻¹ H₂. In situ high-energy synchrotron x-ray diffraction technique together with other microstructure analyses revealed that synergistic effects from Ti₃C₂ MXenes and In nanoparticles (NPs) contributed to the improved kinetics and thermodynamics of MgH₂(Mg): Ti/TiH₂ derived from Ti₃C₂ MXenes accelerated the dissociation and recombination of hydrogen molecule/atoms, while In NPs reduced the thermodynamic stability of MgH₂ by forming the Mg-In solution. Such a strategy of using dual-active hybrid structures to modify MgH₂/Mg provides a new insight for tuning both the hydrogen storage kinetics and thermodynamics of Mg-based hydrides.