Effect of Ti-EG-Ni Dual-Metal Organic Crystal-Derived TiO<sub>2</sub>/C/Ni on the Hydrogen Storage Performance of MgH<sub>2</sub>
Lei Wang, Baozhou Zhao, Jiangchuan Liu, Jianguang Yuan, Yunfeng Zhu, Bogu Liu, Ying Wu, Liquan Li, Yong Cheng, Shichao Zhou
Abstract
To effectively address the kinetic sluggishness associated with MgH 2, this study utilized Ti–EG–Ni dual-metal organic crystal as precursors and employed carburization to prepare the unique rod-shaped structure TiO 2 /C/Ni. The catalyst was incorporated into MgH 2 by ball milling, demonstrating excellent hydrogen storage performance. The composite of MgH 2 –8 wt % TiO 2 /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 % H 2 and absorb 5.72 wt % H 2 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 Mg 2 Ni and semiconductor TiO 2 created a Schottky heterojunction, which stimulated an internal electric field between Ni and TiO 2, accelerating electron transfer. The strong electronic interaction between the catalyst and MgH 2 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 Mg 2 Ni/Mg 2 NiH 4 ), 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 MgH 2 .