Nitrogen Anchoring Effect Triggering Improved Reversible Hydrogen Storage of Mg(BH ₄ ) ₂

ABSTRACT This research uncovered the influence of nitrogen‐doped MXene Ti 3 CN on the reversible hydrogen storage properties of Mg(BH 4 ) 2 . The Mg(BH 4 ) 2 ‐20Ti 3 CN composite began releasing hydrogen at a temperature of 80°C. In addition, the composite discharged over 8.8 wt% hydrogen at a comparatively lower temperature of 270°C, whereas the pure Mg(BH 4 ) 2 emitted merely 5.9 wt% hydrogen under identical circumstances, which exhibited remarkably enhanced dehydrogenation kinetics. Furthermore, upon completion of four cycles, Mg(BH 4 ) 2 ‐20Ti 3 CN retained a reversible hydrogen storage capacity of 4.5 wt%, representing an 80% improvement over the undoped Mg(BH 4 ) 2 . In the course of the dehydrogenation phase, the boron atoms in Mg(BH 4 ) 2 were anchored by nitrogen atoms in Ti 3 CN to form B‐N bonds, which helped suppress the formation of MgB 12 H 12 . During the subsequent rehydrogenation process, the B‐N bonds broke, and the boron atoms reparticipated in the reversible transformation into [BH 4 ] − clusters. Meanwhile, the formation of Ti 0 by the reaction of Mg(BH 4 ) 2 with Ti 3 CN weakened the B‐H bond energy, and the layered structure provided an effective way for hydrogen spillover. These factors collectively improved the reversible hydrogen storage capabilities of Mg(BH 4 ) 2 .