Synergistic Catalytic Impact of Composite Oxide Nb2O5@TiO2-C on the Hydrogen Storage Performance of MgH2

MgH 2 is recognized as an exceptionally promising solid-state material for hydrogen storage, but its high thermodynamic stability, slow kinetics, and cycling-induced particle coarsening remain major obstacles to practical application. In this study, a composite oxide catalyst, Nb 2 O 5 @TiO 2 -C, was synthesized via a hydrothermal route by loading nano-Nb 2 O 5 onto a TiO 2 -C support derived from a Ti-based metal- organic framework. Doping with Nb 2 O 5 @TiO 2 -C markedly enhances the hydrogen storage performance of MgH 2 . Carbon within the support effectively suppresses nanoparticle agglomeration, while the catalyst is partially reduced to low-valence species during de/rehydrogenation cycles, both contributing to the enhanced performance. The MgH 2 -7 wt.% Nb 2 O 5 @TiO 2 -C composite starts dehydrogenating at 210.6 °C. At 300 °C, it rapidly releases over 6 wt% hydrogen within 5 min. The dehydrogenated sample also exhibits fast absorption kinetics, absorbing 6 wt% hydrogen within 1 min at 200 °C under 30 bar H 2 . Moreover, the system shows excellent cycling stability, retaining a hydrogen capacity of 6.6 wt% after 20 cycles.