posted on 2023-11-15, 19:00authored byWajid Ali, Maye Luo, Mengjing Wu, Jaffer Saddique, Yuying Bai, Shujiang Ding, Chengzhang Wu, Weikang Hu
Magnesium
hydride (MgH2) 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 MgH2@3D-TiVCTx 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-TiVCTx MXene structure. These
remarkable results were attributed to the unique 3D-TiVCTx MXene structure and in situ-formed Ti/V nanocatalysts,
which not only stabilized the MgH2 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 MgH2.