Effect of Ti-EG-Ni Dual-Metal Organic Crystal-Derived TiO₂/C/Ni on the Hydrogen Storage Performance of MgH₂

To effectively address the kinetic sluggishness associated with MgH₂, this study utilized Ti-EG-Ni dual-metal organic crystal as precursors and employed carburization to prepare the unique rod-shaped structure TiO₂/C/Ni. The catalyst was incorporated into MgH₂ by ball milling, demonstrating excellent hydrogen storage performance. The composite of MgH₂-8 wt % TiO₂/C/Ni exhibited a lower initial dehydrogenation temperature of 185 °C and a marked dehydrogenation activation energy of 60.537 kJ/mol. At 300 and 150 °C, it only required 300 s to release 6.17 wt % H₂ and absorb 5.72 wt % H₂ within 20 s, respectively. Additionally, the composites demonstrated excellent cycling stability, maintaining 94% reversible capacity after 50 cycles. Theoretical computations suggested that the in situ-generated metal Mg₂Ni and semiconductor TiO₂ created a Schottky heterojunction, which stimulated an internal electric field between Ni and TiO₂, accelerating electron transfer. The strong electronic interaction between the catalyst and MgH₂ weakened the Mg-H bond energy and elongated the Mg-H bond, promoting hydrogen dissociation. During hydrogen absorption and desorption, the composite material exhibited excellent hydrogen storage performance due to the uniform distribution of elements, the in situ-generated catalytic active sites (multivalent Ti and Mg₂Ni/Mg₂NiH₄), and the support provided by carbon to the nanostructures. Our findings provide a deeper understanding of how highly active catalysts of metal oxides/C/Ni enhance the hydrogen storage performance of MgH₂.