Boosting MgH2 hydrogen storage with hydrothermally synthesized FL-V2C-MnO2: Achieving superior performance at low temperatures

In this study, we developed a novel FL-V 2 C-MnO 2 composite catalyst via hydrothermal synthesis, achieving the uniform dispersion of nano-scale MnO 2 particles on few-layer V 2 C MXene substrates. Subsequently, the catalytic effects of this composite on the hydrogen storage performance of MgH 2 were systematically investigated. Remarkably, the MgH 2 system modified with 10 wt% FL-V 2 C-MnO 2 demonstrated superior hydrogen storage characteristics. (1) The initial dehydrogenation temperature decreased substantially to 185 °C (39 % reduction compared to pristine MgH 2 ) with room-temperature hydrogen reabsorption capabilities. (2) At 275 °C, the composite achieved 6.3 wt% hydrogen desorption within 780 s, representing 139 %, 130 %, and 185 % improvements over V 2 C-, FL-V 2 C-, and MnO 2 -doped MgH 2 systems, respectively. Notably, this kinetics enhancement corresponded to a 12.6-fold increase compared to undoped MgH 2 at 325 °C. Mechanistic studies revealed that the synergistic interplay between V 2 C and MnO 2 derivatives established multiphase interfaces that significantly accelerated hydrogen sorption kinetics. Specifically, the in-situ formation of MnO during mechanical activation created abundant active sites, while the two-dimensional V 2 C substrate facilitated electron transfer and prevented nanoparticle agglomeration. This multiscale coordination effect between the MXene support and transition metal oxides established new pathways for destabilizing Mg-H bonds and promoting hydrogen dissociation/recombination processes.