A Phase-Transition Catalyst Bidirectionally Enhances the Hydrogen Absorption/Desorption Kinetics of Mg/MgH₂

Magnesium-based H2 storage material (MgH2) exhibits exceptional prospects for application in the field of solid-state H2 storage. However, its widespread utilization is hindered by slow H2 absorption and desorption kinetics. To address this issue, this study proposes a catalytic strategy that leverages phase transitions in transition metal carbides to bidirectionally augment the kinetic properties of Mg/MgH2, thereby improving its H2 absorption and desorption capabilities. A phase transition catalyst, designated Mo2C–N–CNTs, has been purposefully synthesized through a combination of ion exchange and high-temperature sintering. The Mg@Mo2C–N–CNT composite shows a decrease in the hydrogenation activation energy (Ea) to 19.62 kJ/mol, with the corresponding dehydrogenation Ea value reduced to as low as 75.99 kJ/mol. A newly identified synergistic mechanism, facilitated by the “electronic conduit” effect, effectively catalyzes the dehydrogenation and hydrogenation of Mg/MgH2 when Mo2C phase transition catalysts are integrated with N-doped CNTs. This study presents a promising and innovative prototype for synchrony of hydrogenation and dehydrogenation kinetics in the Mg/MgH2.