Bimetal Three-Dimensional MXene Nanostructures Stabilizing Magnesium Hydrides Realize Long Cyclic Life and Faster Kinetic Rates
Wajid Ali, Maye Luo, Mengjing Wu, Jaffer Saddique, Yuying Bai, Shujiang Ding, Chengzhang Wu, Weikang Hu
Abstract
Magnesium hydride (MgH 2 ) has attracted significant attention as a promising hydrogen storage material due to its large theoretical capacity (7.6 wt %); however, it suffers from high dehydrogenation temperature and poor kinetic rates, which limit its potential applications. Herein, we introduce a strategy for designing the three-dimensional (3D) dual transition metal MXene to tackle these problems simultaneously. The as-synthesized MgH 2 @3D-TiVCT x nanocomposite revealed that the dehydrogenation onset temperature reduced to 170 °C. This composite absorbed hydrogen about 6.5 wt % at 100 °C and released 5.5 wt % at 300 °C within 3 min. Furthermore, this composite achieved a long cyclic performance of 180 cycles at 250 °C with a negligible capacity decrease from 6.5 to 6.3 wt %. Structural analysis after the hydrogenation process and high capacity retention confirmed the stability and robustness of the 3D-TiVCT x MXene structure. These remarkable results were attributed to the unique 3D-TiVCT x MXene structure and in situ-formed Ti/V nanocatalysts, which not only stabilized the MgH 2 nanocrystallines but also provided multiphasic regions and heterojunctions that enhanced hydrogen growth and the recombination mechanism. The designing strategy for synthesizing a bimetallic 3D MXene structure offers valuable insights and opens significant possibilities for tailoring the hydrogen storage performance of MgH 2 .