Mxene as effective matrix for improved reversible hydrogen storage properties of nanoconfined Mg(BH4)2

This study presents the synthesis of novel Mg(BH 4 ) 2 @V 2 C, Mg(BH 4 ) 2 @Nb 2 C and Mg(BH 4 ) 2 @Ti 3 C 2 composites using a solution-based nanoconfinement strategy, achieving robust architecture of Mg(BH 4 ) 2 onto Mxene structures. Among these composites, the Mg(BH 4 ) 2 @V 2 C composite exhibited an initial dehydrogenation temperature of 76.4 °C and released 9 wt% hydrogen at 300 °C, which exhibited the optimal hydrogen release behavior. Its two-step dehydrogenation activation energies (104.44 kJ/mol and 118.52 kJ/mol) were significantly lower than those of pure Mg(BH 4 ) 2 , showing improved dehydrogenation kinetics. After four absorption-desorption cycles, the composite could still desorb 4.9 wt% hydrogen, demonstrating excellent cycling stability. Further structural investigations revealed that V 2 C actually acted as a “functionalized” matrix, which improved hydrogen storage through a combination of nanoconfinement and catalytic effects, promoting both hydrogen desorption and absorption. This work provides critical insights for designing high-performance hydrogen storage materials and advances the development of next-generation storage systems.